homebuilt safety

[anonymous coward]

I'd be grateful if anyone can direct me towards links about the relative
safety of different types of homebuilt aircraft. Not figures I can use to
prove to myself that flying a homebuilt is safe, but a discussion of all
the factors that affect safety in homebuilt aircraft. I haven't found much
through google - perhaps it's a contentious subject?

Though I realise that most of the safety equation is down to the pilot,
presumably some types have safer flying characteristics than others? And
presumably crashes in some types are more survivable than crashes in
others in the same way as some car-wreck scenarios that would have been
lethal 20 years ago are easily survivable today?

AC

[Dave S]

In my opinion, the majority of accidents are the result of human error:
Running out of fuel, running into the ground, running into other planes,
flying into instrument conditions without training (and then losing
control) and the like. Certified versus experimental-amatuer built
status has little to do with these human factors.

If you are looking for a "volvo in the sky" I cant offer much to you.
Trying to derive a relative safety equation is an apples to oranges
affair unless you can account for hours flown per type, pilot experience
and other factors for which the data isnt routinely sampled and available.

The EAA (www.eaa.org) may be a good source to look at for
charactaristics of certain homebuilts. I seem to remember seeing reviews
of some types of homebuilts in their Sport Aviation publication. They
evaluated things such as static and dynamic stability, control forces,
maneuvering characteristics and the like.

The NTSB (www.ntsb.gov) has accident reports available, and searchable,
for several decades. You can look and see what seems to be the most
common causes of accidents for yourself... by type, by date, by
region...etc.

Dave

anonymous coward wrote:
> I'd be grateful if anyone can direct me towards links about the relative
> safety of different types of homebuilt aircraft. Not figures I can use to
> prove to myself that flying a homebuilt is safe, but a discussion of all
> the factors that affect safety in homebuilt aircraft. I haven't found much
> through google - perhaps it's a contentious subject?
>
> Though I realise that most of the safety equation is down to the pilot,
> presumably some types have safer flying characteristics than others? And
> presumably crashes in some types are more survivable than crashes in
> others in the same way as some car-wreck scenarios that would have been
> lethal 20 years ago are easily survivable today?
>
> AC

[EDR]

Somewhere, a long time ago, I was told the number one problem that
occures with homebuilts is fuel system related.
How true that is today, I do not know.
Nowadays, the aircraft are faster and the pilots less experienced.

[Stealth Pilot]

On Fri, 14 May 2004 22:31:56 +0100, anonymous coward
> wrote:

>I'd be grateful if anyone can direct me towards links about the relative
>safety of different types of homebuilt aircraft. Not figures I can use to
>prove to myself that flying a homebuilt is safe, but a discussion of all
>the factors that affect safety in homebuilt aircraft. I haven't found much
>through google - perhaps it's a contentious subject?
>
>Though I realise that most of the safety equation is down to the pilot,
>presumably some types have safer flying characteristics than others? And
>presumably crashes in some types are more survivable than crashes in
>others in the same way as some car-wreck scenarios that would have been
>lethal 20 years ago are easily survivable today?
>
>AC

David Thurston wrote a book called "design for safety"
heavens! published by tab books 9 years ago.

homebuilts are usually lighter in weight which makes them quicker to
move in turbulence. control forces are usually quite light.
they arent any weaker. most designs are built to the same "g" range as
commercial designs.
every homebuilt is a one off constructed aircraft. it has subtle
differences from every other homebuilt ever built. as well they are
usually lighter built. keep all the switches

I took over a hundred hours to get really comfortable in my homebuilt
but now I wouldnt want to go back to commercially produced aircraft.
persist and you will grow to love the quick responsive flight
characteristics.

things break occasionally. I've lost the tailwheel 3 times now and I
am gradually evolving the design. I think I have it just about right
at last.
you can do that with a homebuilt because you dont have a certified
system to confine you. you also dont have the benefits of the
engineering and flight testing that went into sorting out a commercial
design.

more than any other aircraft type a homebuilt's safety rests squarely
on the abilities of the pilot. the upside of that reality is that you
will fly an aircraft you own for more hours and you will be a more
competent pilot as a result.

little things add to survivability. use a lap sash belt or a 5 point
aerobatic harness. dont have switches in the panel area just in front
of you. dont have a sharp edge to the top of the instrument panel.
dont fly the thing if there is a maintenance issue. fix it first.

I have never felt endangered in all the time I've flown mine.
once you get a real aircraft in your hands I'm sure you'll feel just
at ease.
Stealth Pilot

[anonymous coward]

On Fri, 14 May 2004 22:17:24 +0000, Dave S wrote:

> In my opinion, the majority of accidents are the result of human error:
> Running out of fuel, running into the ground, running into other planes,
> flying into instrument conditions without training (and then losing
> control) and the like. Certified versus experimental-amatuer built
> status has little to do with these human factors.

I feel very human. That's the problem... I currently fly hang-gliders, and
on my first long flight I stalled at about 10M AGL (wind gradient). I bent
the base bar by landing on it, but as luck had it, I was in a harness for
a tandem glider and had a double parachute between my chest and the
aluminium. I think I broke a rib or two anyway, but I'm sure the passive
safety of having a parachute under my chest saved me from more serious
injury.

A friend has the wreck of a homebuilt in his garage. Again, the pilot
stalled at low altitude, but in his case the fuselage broke in half around
the pilot compartment and his injuries were much more serious than mine.

> If you are looking for a "volvo in the sky" I cant offer much to you.
> Trying to derive a relative safety equation is an apples to oranges
> affair unless you can account for hours flown per type, pilot experience
> and other factors for which the data isnt routinely sampled and available.

I agree this sounds impossibly fraught. What I would like (ideally) would
be the results of something akin to the car-crash tests that show how the
test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
documentary about car-safety a few years ago, that mentioned that the
technology of crumple-zones and reinforced passenger compartments was
originally developed for WWII naval aircraft. Don't homebuilt designers
think about features such as these? Or would they help in so few scenarios
that it's an irrelevance?

> The EAA (www.eaa.org) may be a good source to look at for
> charactaristics of certain homebuilts. I seem to remember seeing reviews
> of some types of homebuilts in their Sport Aviation publication. They
> evaluated things such as static and dynamic stability, control forces,
> maneuvering characteristics and the like.
>
> The NTSB (www.ntsb.gov) has accident reports available, and searchable,
> for several decades. You can look and see what seems to be the most
> common causes of accidents for yourself... by type, by date, by
> region...etc.

Thanks, I'll have a browse.

AC

> Dave
>
> anonymous coward wrote:
>> I'd be grateful if anyone can direct me towards links about the relative
>> safety of different types of homebuilt aircraft. Not figures I can use to
>> prove to myself that flying a homebuilt is safe, but a discussion of all
>> the factors that affect safety in homebuilt aircraft. I haven't found much
>> through google - perhaps it's a contentious subject?
>>
>> Though I realise that most of the safety equation is down to the pilot,
>> presumably some types have safer flying characteristics than others? And
>> presumably crashes in some types are more survivable than crashes in
>> others in the same way as some car-wreck scenarios that would have been
>> lethal 20 years ago are easily survivable today?
>>
>> AC

[Pete Schaefer]

Landing speeds are a big driver for the amount of injury. I think that the
FAA has a lot of data on this. Can't think of a reference off-hand, but you
can search the NTSB site. But anyway, here's the math: KE = (1/2)mv^2. The
basic conclusion is that accidents occuring at lower landing speeds do less
damage. This was a driver for the design of the RV series aircraft. If you
want safety, get something with STOL capability, make sure there's nothing
in the cockpit that's going to smack you in the back of the head if you
screw up, then practice, practice, practice (with an instructor until you
feel confident).....then practice some more. Avoid low-level aerobatics
until you're a really ****-hot pilot.

You really need to forget about structural protection in a home-built. The
key is to prevent (by flight procedure, pilot skill and knowledge, and by
appropriate vehicle design) accidents from happening in the first place.

Pete
[RV-8A in the planning stages....new shop under construction]

"anonymous coward" > wrote in message
...
> I agree this sounds impossibly fraught. What I would like (ideally) would
> be the results of something akin to the car-crash tests that show how the
> test-dummies fared in various scenarios - e.g. side impacts etc... I saw a

[Ron Wanttaja]

I performed a fairly in-depth study of homebuilt accidents towards the end
of last year. The October issue of KITPLANES magazine will include an
article summarizing my results and conclusions.

During my analysis, I looked at the records of individual designs, thought
I didn't include the results in the article. Even though I performed my
analysis on a three-year period, the number of accidents of most particular
types is still fairly low that minor aberrations cause significant changes.

For instance, if there are 2000 examples of type "A" and 200 examples of
type "B", one or two extra crashes will affect the stats for Type "B" a lot
more than Type "A". If 20 Type "A" planes and 2 type "B" planes crash,
they both have the same accident rate. If both have two additional
accidents, Type "B"'s rate will now be almost *double* Type "A"'s. But
does that truly mean that "B" is twice as dangerous as "A"?

We also get into the aircraft type and aircraft operating mode issues. On
my first pass, I found one type of homebuilt with a significantly higher
accident rate than the rest. When I looked closer, I realized that this
was an amphibian...and a lot of the accidents were during water operations.

So I'm reluctant to point fingers are individual aircraft types. Here's a
list of the fleet accident rate (what percentage of a particular type
crashes in an average year) for ten major homebuilt kit companies. Note
that the statistics for companies with multiple types are grouped together
(e.g. the RV series is lumped under one, not listed individually). Only
aircraft listed as being licensed were included...many homebuilts of these
types are on the registration rolls but have the certification type column
blank.

The aircraft included are (in alphabetical order): Avid, Glasair, Glastar,
Kitfox, Lancair, Long EZ, RANS, T-18, Vans, Velocity. Note that this order
does NOT match that of the table below, nor does it include the amphibian
type I mention above.

Annual Accident Rate
% of Fleet
A 1.3%
B 1.2%
C 1.8%
D 4.9%
E 0.9%
F 1.0%
G 0.7%
H 2.4%
I 1.9%
J 2.9%


Ron Wanttaja

[Dave S]

<SNIP>
> I agree this sounds impossibly fraught. What I would like (ideally) would
> be the results of something akin to the car-crash tests that show how the
> test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
> documentary about car-safety a few years ago, that mentioned that the
> technology of crumple-zones and reinforced passenger compartments was
> originally developed for WWII naval aircraft. Don't homebuilt designers
> think about features such as these? Or would they help in so few scenarios
> that it's an irrelevance?
>


Again, I have read (but dont have the source handy) that one of the
biggest determinants of lethality in a small aircraft accident is based
on wether the aircraft contacts the ground in a near-level, controlled
attitude (or not). Crumple zones and side-impact airbags wont do much
when you hit upside down, in a spin, or screaming out of the sky with a
yard dart's downward trajectory. Preventing departure from controlled
flight is the key to survival. That is why you 1) ALWAYS fly the plane
first and 2) NEVER give up.

Dave

[anonymous coward]

On Sat, 15 May 2004 15:14:41 +0000, Pete Schaefer wrote:

> Landing speeds are a big driver for the amount of injury. I think that the
> FAA has a lot of data on this. Can't think of a reference off-hand, but you
> can search the NTSB site. But anyway, here's the math: KE = (1/2)mv^2. The
> basic conclusion is that accidents occuring at lower landing speeds do less
> damage. This was a driver for the design of the RV series aircraft. If you
> want safety, get something with STOL capability, make sure there's nothing
> in the cockpit that's going to smack you in the back of the head if you
> screw up, then practice, practice, practice (with an instructor until you
> feel confident).....then practice some more. Avoid low-level aerobatics
> until you're a really ****-hot pilot.

I like the look of the IBIS (http://www.junqua-aircraft.com/) and I'd
prefer to build in wood. But the more I read, the less good an idea the
Ibis seems (fast landing speeds - only a few complete, so perhaps more
prone to 'bugs' than established designs such as the LongEZ and friends).

I feel more and more drawn towards the idea of building a wooden 3-axis
microlight - some of them seem to have quite short build times, and as you
say, slow landing speeds have got to be a good thing.

> You really need to forget about structural protection in a home-built. The
> key is to prevent (by flight procedure, pilot skill and knowledge, and by
> appropriate vehicle design) accidents from happening in the first place.

I hope I don't seem paranoid, but assuming I'm likely to be flying for 50
years, even accident rates down in the low percents seem quite alarming.

Always grateful for advice,

AC


> Pete
> [RV-8A in the planning stages....new shop under construction]
>
> "anonymous coward" > wrote in message
> ...
>> I agree this sounds impossibly fraught. What I would like (ideally) would
>> be the results of something akin to the car-crash tests that show how the
>> test-dummies fared in various scenarios - e.g. side impacts etc... I saw a

[anonymous coward]

On Sat, 15 May 2004 19:34:27 +0000, Ron Wanttaja wrote:

> I performed a fairly in-depth study of homebuilt accidents towards the end
> of last year. The October issue of KITPLANES magazine will include an
> article summarizing my results and conclusions.

Thanks, I'll look forward to the article.

AC

[Paul Lee]

Statistically, takeoffs are more lethal than landings, even though
landings take more skill for a good "show". During initial takeoff a
typical aircraft is just above stall and climbing. An engine failure
on takeoff near ground could easily put you in a stall where recovery
is slim and nose down is more probable - and you "collide" with the
earth. In a conventional aircraft I prefer rotating at a higher speed
than customary, and get the extra speed edge to glide down to earth in
case of engine failure.

In landing problems landing speed itself is not much of a factor
unless you collide with something. Aside from fire or tiping over
remote possibility, higher landing speed along the runway simply
results in a longer slide. Recently an individual came down in a storm
and busted their landing gear on touchdown with same type of aircraft
as mine and resulted in no injury and relatively little damage to
aircraft. This was inspite of the fact that the touchdown speed is 90+
mph.

--------------------------------------------
Paul Lee, SQ2000 canard: www.abri.com/sq2000

"Pete Schaefer" > wrote in message news:<Btqpc.53022$536.9082680@attbi_s03>...
> Landing speeds are a big driver for the amount of injury. I think that the
> FAA has a lot of data on this. Can't think of a reference off-hand, but you
> can search the NTSB site. But anyway, here's the math: KE = (1/2)mv^2. The
> basic conclusion is that accidents occuring at lower landing speeds do less
> damage. This was a driver for the design of the RV series aircraft. If you
> want safety, get something with STOL capability, make sure there's nothing
> in the cockpit that's going to smack you in the back of the head if you
> screw up, then practice, practice, practice (with an instructor until you
> feel confident).....then practice some more. Avoid low-level aerobatics
> until you're a really ****-hot pilot.
>
> You really need to forget about structural protection in a home-built. The
> key is to prevent (by flight procedure, pilot skill and knowledge, and by
> appropriate vehicle design) accidents from happening in the first place.
>
> Pete
> [RV-8A in the planning stages....new shop under construction]
>
> "anonymous coward" > wrote in message
> ...
> > I agree this sounds impossibly fraught. What I would like (ideally) would
> > be the results of something akin to the car-crash tests that show how the
> > test-dummies fared in various scenarios - e.g. side impacts etc... I saw a

[Stealth Pilot]

On Sun, 16 May 2004 16:42:03 +0100, anonymous coward
> wrote:

>On Sat, 15 May 2004 15:14:41 +0000, Pete Schaefer wrote:
>
>> Landing speeds are a big driver for the amount of injury. I think that the
>> FAA has a lot of data on this. Can't think of a reference off-hand, but you

>
>I like the look of the IBIS (http://www.junqua-aircraft.com/) and I'd
>prefer to build in wood. But the more I read, the less good an idea the
>Ibis seems (fast landing speeds - only a few complete, so perhaps more
>prone to 'bugs' than established designs such as the LongEZ and friends).

china plate (mate) if you want a very good economical wood design then
the Corby Starlet has a lot to offer. it is aerobatic to 4g. has
something like 33 years of safe proven use. its a design that has
never had an AD issued for it. the owners I know just love them.
very few have ever been pranged.

recommended engine is a jabiru 2200cc. delivers about 11litres per
hour fuel burn and can see the starlet to Vne in level flight.

btw it is a real aeronautical engineer designed aeroplane.
plans are about $aus200. 'bout $US150.

do a web search for "Corby Starlet"

Stealth Pilot

[Richard Riley]

On 16 May 2004 18:22:21 -0700, (Paul Lee)
wrote:

:This was inspite of the fact that the touchdown speed is 90+
:mph.

Oh, sweet Jesus, I hope you're kidding. What empty weight and CG
range are you running?

[Ernest Christley]

anonymous coward wrote:

>
> I agree this sounds impossibly fraught. What I would like (ideally) would
> be the results of something akin to the car-crash tests that show how the
> test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
> documentary about car-safety a few years ago, that mentioned that the
> technology of crumple-zones and reinforced passenger compartments was
> originally developed for WWII naval aircraft. Don't homebuilt designers
> think about features such as these? Or would they help in so few scenarios
> that it's an irrelevance?
>

John Dyke did. The front page of my websitehas a 3D CAD rendering of
the cockpit with a pilot seated. Note the comparatively HUGE crumple
zone in front and to each side enjoyed by the pilot compared to most
designs. For most designs, trying to get this sort of crumple zone
would make the craft extremely safe...'cause it'd be so heavy that it'd
never fly!!

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[[email protected]]

On Sat, 15 May 2004 15:09:43 +0100, anonymous coward
> wrote:

>I agree this sounds impossibly fraught. What I would like (ideally) would
>be the results of something akin to the car-crash tests that show how the
>test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
>documentary about car-safety a few years ago, that mentioned that the
>technology of crumple-zones and reinforced passenger compartments was
>originally developed for WWII naval aircraft

I'm pretty surprised to hear about this. My knowledge, such as it is,
about WWII fighters in general, and Navy fighters in particular is
that they were either designed with production/armament in mind or
aerodynamics (speed or maneuverability) in mind, but building
"crumple-zones" wasn't a priority, if they even knew of the concept in
1940.

This is especially true for the Navy fighters which had to do all the
things the non Navy fighters did, but in addition they had to crash
repeatedly on the carrier deck in what the Navy laughably calls
"landings". Needless to say, they were supposed to be in one piece
after every landing, which means that they ended up heavier in general
than the typical same size Army fighter.

It just happens that in a violent crash, the outer appendages will
tend to shed from the airplane. I've seen footage of an F6F botching
the landing and colliding with the island, after which the only thing
left intact was the cockpit, with the pilot still in it. But I doubt
that Grumman planned on guys hitting the island when they designed the
airplane, it's just that it shed all it's heavy pieces during the
oblique impact. The pilot was extremely lucky he did not hit head on:
he would have been the crumple zone.

Corky Scott

[Corrie]

anonymous coward > wrote in message >...

> I feel more and more drawn towards the idea of building a wooden 3-axis
> microlight - some of them seem to have quite short build times, and as you
> say, slow landing speeds have got to be a good thing.

Have a look at the Evans VP-1 "Volkplane" or the Bowers "FlyBaby".
The VP is simpler, but the FB has a better look IMO. Both designs
date from the 60's and have scores of examples flying with thousands
of hours accumulated. Both have active builder/pilot groups on Yahoo.
Ron Wanntaja maintains an excellent website at www.bowersflybaby.com

Ditto the other comments in this thread - in any aircraft the
component most susceptible to catastrophic failure is the nut behind
the stick.

Good luck to you!

--Corrie, gettin' ready to cut wood for a FlyBaby

[anonymous coward]

On Mon, 17 May 2004 13:29:04 -0400, charles.k.scott wrote:

> On Sat, 15 May 2004 15:09:43 +0100, anonymous coward
> > wrote:
>
>>I agree this sounds impossibly fraught. What I would like (ideally) would
>>be the results of something akin to the car-crash tests that show how the
>>test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
>>documentary about car-safety a few years ago, that mentioned that the
>>technology of crumple-zones and reinforced passenger compartments was
>>originally developed for WWII naval aircraft
>
> I'm pretty surprised to hear about this. My knowledge, such as it is,
> about WWII fighters in general, and Navy fighters in particular is
> that they were either designed with production/armament in mind or
> aerodynamics (speed or maneuverability) in mind, but building
> "crumple-zones" wasn't a priority, if they even knew of the concept in
> 1940.

The argument, provided I'm not confabulating it, was that there was a
shortage of combat pilots so it was worthwhile building a 'plane that
let them live to crash again.

> This is especially true for the Navy fighters which had to do all the
> things the non Navy fighters did, but in addition they had to crash
> repeatedly on the carrier deck in what the Navy laughably calls
> "landings". Needless to say, they were supposed to be in one piece
> after every landing, which means that they ended up heavier in general
> than the typical same size Army fighter.
>
> It just happens that in a violent crash, the outer appendages will tend
> to shed from the airplane. I've seen footage of an F6F botching the
> landing and colliding with the island, after which the only thing left
> intact was the cockpit, with the pilot still in it. But I doubt that
> Grumman planned on guys hitting the island when they designed the
> airplane, it's just that it shed all it's heavy pieces during the
> oblique impact. The pilot was extremely lucky he did not hit head on:
> he would have been the crumple zone.

The footage I remember was of a prop-plane coming in to land very heavily.
The entire aircraft snapped in two behind the pilot compartment. Suffice
to say, Google can't find any link between "crumple-zone" and "aircraft
carrier" so it's possible my memory has gone cloudy.

AC

[Paul Lee]

Richard Riley > wrote in message >...
> On 16 May 2004 18:22:21 -0700, (Paul Lee)
> wrote:
>
> :This was inspite of the fact that the touchdown speed is 90+
> :mph.
>
> Oh, sweet Jesus, I hope you're kidding. What empty weight and CG
> range are you running?

Don't think you are informed about canards - especially faster ones.

And there is no need to trivialize/misuse Jesus name, it is revered by me
and many others.

Paul Lee.

[nauga]

Paul Lee wrote:

> Don't think you are informed about
> canards - especially faster ones.

If you'd care to place a wager on
Richard 'Renaissance' Riley's knowlege of canards
a good portion of the newsgroup would probably take
you up on it <g>

So, like he asked, at what weight do you use a *touchdown*
speed in excess of 90 knots? Heck, what's your tire speed?
That's pretty fast for a well-designed GA canard unless it's
pretty freakin' heavy.

Dave 'sssssmokin' Hyde

[Richard Riley]

On 17 May 2004 18:02:56 -0700, (Paul Lee)
wrote:

:Richard Riley > wrote in message >...
:> On 16 May 2004 18:22:21 -0700, (Paul Lee)
:> wrote:
:>
:> :This was inspite of the fact that the touchdown speed is 90+
:> :mph.
:>
:> Oh, sweet Jesus, I hope you're kidding. What empty weight and CG
:> range are you running?
:
:Don't think you are informed about canards - especially faster ones.

I think I am.

:And there is no need to trivialize/misuse Jesus name, it is revered by me
:and many others.

It is my profound wish that you delay meeting him as long as possible.

The closest canard type to yours is the Cozy Mk 4 - the same planform
and airfoils, the same engine, the same number of seats at the same
fuselage stations. Performance-wise, the only big airframe difference
is the retractable main gear (and the horrible back end of the SQ's
cowl.)

Generally speaking, a Mk 4 will touch down at about 75 mph - 100
downwind, 90 base, 80-85 on short final. Significant forward CG (in
the 98" range) heavy gross weigh or cross winds might add 5 mph or so.

Those are about the same numbers most people use for a Long EZ with a
big engines. Berkut with a 540 is a bit faster, it will touch down
closer to 80. A light, small engine EZ will touch down a bit slower,
in the 65-70 mph range.

The difference between a 75 mph touchdown and a 90+ mph touchdown is
significant. It's a 44% + increase in your momentum. I know the
Matco W50L's are good, but do you want to get rid of that much of the
margin?

Low speed handling is significantly improved by trailing edge fences,
you may want to look into them.
http://www.lsecorp.com/KlausInfo/Flowfence.htm

[Richard Riley]

On Mon, 17 May 2004 20:54:38 +0100, anonymous coward
> wrote:

:On Mon, 17 May 2004 13:29:04 -0400, charles.k.scott wrote:
:
:> On Sat, 15 May 2004 15:09:43 +0100, anonymous coward
:> > wrote:

:
:The argument, provided I'm not confabulating it, was that there was a
:shortage of combat pilots so it was worthwhile building a 'plane that
:let them live to crash again.

I've never heard of crash-survivability being a factor in WW2 fighers,
but I have read that more Navy pilots were lost in training than in
combat.

[Richard Lamb]

Richard Riley wrote:
>
> On Mon, 17 May 2004 20:54:38 +0100, anonymous coward
> > wrote:
>
> :On Mon, 17 May 2004 13:29:04 -0400, charles.k.scott wrote:
> :
> :> On Sat, 15 May 2004 15:09:43 +0100, anonymous coward
> :> > wrote:
>
> :
> :The argument, provided I'm not confabulating it, was that there was a
> :shortage of combat pilots so it was worthwhile building a 'plane that
> :let them live to crash again.
>
> I've never heard of crash-survivability being a factor in WW2 fighers,
> but I have read that more Navy pilots were lost in training than in
> combat.

Well, they didn't call it Grumman Iron Works for nothing...

[Paul Lee]

Richard Riley > wrote in message >...
>.............
> The difference between a 75 mph touchdown and a 90+ mph touchdown is
> significant. It's a 44% + increase in your momentum.

Its a 44% increase in KE, not momentum (20%). But so what? Both
momentum and KE are relative only to other objects that shouldn't be
on the runway anyway. Turboprops, jets, have higher touchdown speeds.

>... I know the
> Matco W50L's are good, but do you want to get rid of that much of the
> margin?

You mean brake wear? Typically canard flyers let it roll down the runway
to save brakes. The lighter vari-ez would have less problem
with stopping distance - is that the canard that you fly?

> Low speed handling is significantly improved by trailing edge fences,
> you may want to look into them.
> http://www.lsecorp.com/KlausInfo/Flowfence.htm

They also have a problem with low speed roll control which is eliminated
with the higher speed touchdown/takeoff - which also eliminates prop torque
issues on takeoff.

Even in a conventional planes with no flaps, you land more
stable at higher landing speeds - a little more runway.

BTW Cozy Mark IV is about 200 lbs lighter than SQ2000.

[[email protected]]

On 17 May 2004 18:02:56 -0700, (Paul Lee)
wrote:

>Richard Riley > wrote in message >...
>> On 16 May 2004 18:22:21 -0700, (Paul Lee)
>> wrote:
>>
>> :This was inspite of the fact that the touchdown speed is 90+
>> :mph.
>>
>> Oh, sweet Jesus, I hope you're kidding. What empty weight and CG
>> range are you running?
>
>Don't think you are informed about canards - especially faster ones.

Ooooohhhhh Paul, do you know who Richard Riley is? He used to be
involved with producing the Berkut. They aren't too many people on
earth who know more about canard type airplanes than him. A few
perhaps, but not too many.

Corky Scott

[nauga]

Paul Lee wrote...

> Its a 44% increase in KE, not momentum (20%). But so what? Both
> momentum and KE are relative only to other objects that shouldn't be
> on the runway anyway.

Silly me, and here I thought I higher KE at touchdown would
result in longer landing distances - a 44% increase a *much*
longer rollout.

> You mean brake wear? Typically canard flyers let it roll down the runway
> to save brakes.

Greater than 90 knots and no braking on rollout? What's you're
minimum field length?

> Even in a conventional planes with no flaps, you land more
> stable at higher landing speeds - a little more runway.

So do you pad your approach speed to come up with the 90+
figure or is that the designer's recommendation?
It strikes me as obscenely fast, even compared to other canards.

Dave 'FBAW' Hyde

[Paul Lee]

wrote in message >...
> On 17 May 2004 18:02:56 -0700, (Paul Lee)
> wrote:
>
> >Richard Riley > wrote in message >...
> >> On 16 May 2004 18:22:21 -0700, (Paul Lee)
> >> wrote:
> >>
> >> :This was inspite of the fact that the touchdown speed is 90+
> >> :mph.
> >>
> >> XXXXXXXXXXXXXXXXXXXXXXXXXXXXX What empty weight and CG
> >> range are you running?
> >
> >Don't think you are informed about canards - especially faster ones.
>
> Ooooohhhhh Paul, do you know who Richard Riley is? He used to be
> involved with producing the Berkut. They aren't too many people on
> earth who know more about canard type airplanes than him. A few
> perhaps, but not too many.
>
> Corky Scott

Corky,

I am not interested in a who's who contest. Just the issues. The fact
is that I just came back from factory flight training in the SQ2000
and consistently touched down at about 90mph and took off about 90+.
It is a faster, somewhat heavier aircraft (gross 2250) with about a
28' wingspan. The CG was in the middle and weight was not anywhere
maxed out. A Velocity has about 30' wing span giving it the extra lift
at slower speed but pays the cost at high end - unless you have 300hp.

While its possible to land a canard slow, its not as stable and a
number of canard flyers will land at higher speed in order to see the
runway.

[Marc J. Zeitlin]

Paul Lee wrote;

> I am not interested in a who's who contest. Just the issues.

OK, let's address them.

>.....The fact
> is that I just came back from factory flight training in the SQ2000
> and consistently touched down at about 90mph and took off about 90+.

If this is what they're teaching you at the factory, then they're doing
their builders a disservice.

> It is a faster, somewhat heavier aircraft (gross 2250) with about a
> 28' wingspan. The CG was in the middle and weight was not anywhere
> maxed out.

I have landed my COZY MKIV at extreme forward CG position at a gross
weight of 2150 lb. The fastest I will touch down is about 85 mph in that
configuration. As Richard has pointed out, 75 mph touchdown speeds are
closer to the norm, and is what I was taught when getting checked out in
other COZY's. I have about 160 hours and 300 or so landings in my
plane - I have NEVER felt the need to come in any faster, even in a 15
kt. crosswind with 5-10 kt. gusts.

>.....A Velocity has about 30' wing span giving it the extra lift
> at slower speed but pays the cost at high end - unless you have 300hp.

But no one was discussing Velocitys. Richard clearly pointed out the
comparison to the COZY MKIV, which the SQ-2000 bears the most
resemblance to, from a size, weight, and power standpoint.

> While its possible to land a canard slow, its not as stable and a
> number of canard flyers will land at higher speed in order to see the
> runway.

Well, I don't know where you're getting your information, because the
three COZY's I've flown as PIC (from both right and left seat) have had
no "stability" issue whatsoever at touchdown speeds down to 70 mph (or
even 65 mph, with rearmost CG and light weight). Almost all the L.E. and
V.E. folks I know also land in the 70-80 mph range, at the most. As long
as I keep the canard on or below the horizon, I can land at these
speeds, see the runway, and have no stability issues.

Anyone landing faster than that is doing so because they do not know how
to correctly land a canard aircraft. I'd like to see you land a SQ-2000
(or a COZY) on a 2500 ft. runway, touching down at 90 mph. I have no
problem doing it in my plane, using slower speeds, even in relatively
strong crosswinds, and at high weights.

Tell you what, Paul - I'm not interested in a ****ing contest - I'm
interested in safety. I'll be happy to check you out in my COZY MKIV
(left seat, if you'd like) if you'd like to come to MA before your first
flight, so you can see the difference. Let me know.

--
Marc J. Zeitlin
http://marc.zeitlin.home.comcast.net/
http://www.cozybuilders.org/
Copyright (c) 2004

[Richard Riley]

On 18 May 2004 07:15:20 -0700, (Paul Lee)
wrote:

:Richard Riley > wrote in message >...
:>.............
:> The difference between a 75 mph touchdown and a 90+ mph touchdown is
:> significant. It's a 44% + increase in your momentum.
:
:Its a 44% increase in KE, not momentum (20%).

OK, let's be precise. On landing you intend to have 44% (plus) more
kinetic energy than other airplanes with exactly the same weight, wing
and engine. That's going to result in a 44% (plus) longer stopping
distance (as the brakes get hot, they also become less effective, so
it's not a 1:1 ratio). But that's once you're able to actually put it
on the runway. The high L/D that the canards enjoy means they tend to
float a lot down the runway, so when you're landing fast it's very
hard to touch down close to the numbers. Your retract gear will help
that, somewhat, by making the aircraft dirtier in the pattern, and
easier to slow down, than something with fixed and faired gear with
wheel pants. In any event, you will be landing much faster and longer
than other aircraft with identical performance.

:But so what? Both
:momentum and KE are relative only to other objects that shouldn't be
:on the runway anyway.

And, as everyone knows, nothing ever goes wrong. There is never
anything on the runway that shouldn't be there. You never have to
land on a shorter runway than you intend, and you never land at higher
than expected density altitude.

:Turboprops, jets, have higher touchdown speeds.

Turboprops and jets have longer runway requirements, greater crash
protection requirements, more frequent inspections, and higher pilot
requirements. Most require 2 pilots. Having the landing requirements
of a jet, and the maintenance requirements and speed of a piston prop,
is not a good compromise.

:
:>... I know the
:> Matco W50L's are good, but do you want to get rid of that much of the
:> margin?
:
:You mean brake wear? Typically canard flyers let it roll down the runway
:to save brakes.

No, I mean brake fade. The W50L disk is good for about 190k ft/lbs
each. The total energy that can be absorbed by a brake disk is
dependent on it's material and mass. Your airplane at full gross
weight and 95 mph has 340k ft/lbs of energy. So you are down under
10% for your safety margin. Don't land at Denver in the summer.

:The lighter vari-ez would have less problem
:with stopping distance - is that the canard that you fly?

It's a derivative of the Vari-Eze (proper spelling, we must be
precise, after all) but it's a little faster. I'll make you a deal.
When you get your plane done, I'll race you for pink slips, or a
bottle of 30 year old single malt. I'll even spot you extra 100 lbs.
in payload.

:
:> Low speed handling is significantly improved by trailing edge fences,
:> you may want to look into them.
:> http://www.lsecorp.com/KlausInfo/Flowfence.htm
:
:They also have a problem with low speed roll control which is eliminated
:with the higher speed touchdown/takeoff - which also eliminates prop torque
:issues on takeoff.

At 200 hp, you won't have any issue with prop torque. And I've never
had a significant problem with low speed control, provided CG is
within the envelope. Just a touch of adverse yaw, below 110 kts.
Lower winglets (even small ones) help that significantly by damming
off the high pressure at the outboard end. Filleting the wing TE back
to the winglet TE with a pen-nib fairing (you can see it on the
Delaminator, at SnF or Osh), the standard vortalons, and Klaus' TE
fences all help lower the minimum airspeed.
:
:Even in a conventional planes with no flaps, you land more
:stable at higher landing speeds - a little more runway.

If you are landing on 8000 feet, or even 5000, it's not a problem.
Try putting in on 2500 over some trees at the end of the runway, it's
a problem.

:
:BTW Cozy Mark IV is about 200 lbs lighter than SQ2000.

Now that's strange, isn't it. Empty weight on a Cozy Mk 4 is
generally around 1100-1200 with a 2050 lb gross. On the Speed Queen,
you're looking at close to the same empty - 1100-1250. That makes
sense, its the same wing, the same engine, the same size fuselage, the
same materials. You save a little weight with vacuum bagging (not as
much as you'd think, but some) and loose a little with the retract
gear.

(And you gain a little in drag reduction with the retract gear, but
again, not as much as you might think. Fairing the legs and putting a
good set of wheel pants on the gear will eliminate 90% of the drag of
the gear. Retracting them gets rid of that last 10% - in exchange for
the weight and complexity of a retract system, increased insurance
rates and pilot requirements, a less forgiving failure mode and more
maintenance. There are a number of airplanes that fly slower with a
retractable gear than with a well faired gear.)

So, with the same empty weight, cabin dimensions, wing and engine, if
you have the same fuel load, baggage and passenger weight, the two
airplanes will take off, climb, cruise and land pretty much the same.

But the max gross weight is different - 2250 listed by Stan for the
Speed Queen. That's 10% more than the Cozy. Is it because the Speed
Queen is so much stronger than the Cozy? That seems unlikely,
composite aircraft - especially fiberglass aircraft - are generally
engineered to minimum stiffness requirements, rather than failure
loads. As a result, they usually end up much stronger than they need
to be. Their gross weights are dictated by performance, rather than
ultimate load.

So, basically, Stan is willing to accept less takeoff, climb, cruise
and landing performance at full gross weight than Nat, in exchange for
a higher useful load.

But there seems to be something wrong there, too. The KLS web site
doesn't seem to exist any more, but the old numbers I have in my files
show a sea level max gross climb rate of 2200 FPM. Since the Cozy,
with it's lighter max weight, only claims 1200 FPM at 2050 gross, the
Speed Queen number seems optimistic to me. The same is true on the
top end - SQ claims 258 MPH Vmax, Cozy 4 claims 220 mph and
demonstrates (CAFE test) 209.8 mph at 1668 lb, 29.2", 2691 rpm, 12.9
gph.

Can it be that the SQ fuselage shape is so superior to the Cozy that
it's flying 25% faster and climbing almost twice as fast? It seems
unlikely.

But all the power performance numbers aside, it's simply should not be
necessary to land at 90+ mph. Airplanes with exactly the same flying
surfaces and weight touch down at 75-80. When I say exactly, I mean
exactly - to the fraction of an inch in planform, with the same
templates, with the same modified Eppler airfoil on the mains, and the
same Roncz 1145 MS on the canard. (BTW, the MS stands for Mike and
Sally Mellville, no matter what you've been told)

Landing that fast increases risk, limits the airports you can land at,
and increases wear. If there is an accident of any kind, it's
significantly worse. The same accident that's survivable at 75 MPH
and 1 degree impact angle is not remotely survivable at 90 mph and 1
degree. That's the biggest reason to fly the left hand part of the
envelope, as well as the right.

[Paul Lee]

Hmmmmm... I was answering Richard and now I get Dave...???

"nauga" > wrote in message >...
> Paul Lee wrote...
>
> > Its a 44% increase in KE, not momentum (20%). But so what? Both
> > momentum and KE are relative only to other objects that shouldn't be
> > on the runway anyway.
>
> Silly me, and here I thought I higher KE at touchdown would
> result in longer landing distances - a 44% increase a *much*
> longer rollout.
>
> > You mean brake wear? Typically canard flyers let it roll down the runway
> > to save brakes.
>
> Greater than 90 knots and no braking on rollout? What's you're
> minimum field length?
>
> > Even in a conventional planes with no flaps, you land more
> > stable at higher landing speeds - a little more runway.
>
> So do you pad your approach speed to come up with the 90+
> figure or is that the designer's recommendation?
> It strikes me as obscenely fast, even compared to other canards.
>
> Dave 'FBAW' Hyde
>

[Richard Riley]

On 18 May 2004 22:38:28 -0700, (Paul Lee)
wrote:

:Hmmmmm... I was answering Richard and now I get Dave...???

Yes, it's a newsgroup, read by (and responded to by) many people.
You'll find *my* answer a couple of posts down.

[Paul Lee]

Thanks for taking time to deal with more detail. Although
you included many more issues than I raised. And I am sure
the KE/mv confussion was just a slip of the pen. But let
me just clarify some things:

Richard Riley > wrote in message >...
> ................
> But there seems to be something wrong there, too. The KLS web site
> doesn't seem to exist any more, but the old numbers I have in my files
> show a sea level max gross climb rate of 2200 FPM. Since the Cozy,
> with it's lighter max weight, only claims 1200 FPM at 2050 gross, the
> Speed Queen number seems optimistic to me. The same is true on the
> top end - SQ claims 258 MPH Vmax, Cozy 4 claims 220 mph and
> demonstrates (CAFE test) 209.8 mph at 1668 lb, 29.2", 2691 rpm, 12.9
> gph.
> ...........

KLS website is gone because KLS is in process of changing name. KLS
was a partnership and one of the partners left. The new name
is Advanced Composite Design, Inc. KLS has also just finished developing
a new desing of a large plane (tested and flying). Thats explained at my
website http://www.abri.com/sq2000

I just came back from SQ2000 factory training.
I haven't tried the factory model to Vne. I was mainly interested in
take off and landing skills. But Stan indicated he achieves 230mph
cruise. But isn't Cozy IV fixed main gear? That would explain some of
the difference.

> Landing that fast increases risk, limits the airports you can land at,
> and increases wear. .........

True. But in my case we have two 6800 x 150 foot runways. In SQ2000
factory flight training I was instructed to touchdown at 90MPH and did
consistently and the bird exhibited no problem behaviour. I am sure
that after I get a lot more hours experience like you or Stan, I'll be
able to cut the landing speed. If you are around Pierre, SD you are
welcome to check out my bird.

Interestingly, while on the subject of safety, about 6 weeks ago, the
KLS SQ2000 came down in a storm and busted the landing gear. It slid
down the runway and into a ditch. No injuries, it did not flip over,
and surprisingly the damage was mainly to the landing gear and the
prop (toothpicks all over) - very little other damage.

[Ed Wischmeyer]

> And, as everyone knows, nothing ever goes wrong. There is never
> anything on the runway that shouldn't be there. You never have to
> land on a shorter runway than you intend, and you never land at higher
> than expected density altitude.

Not to mention off-runway landings... there's the real rub for safety.

If the runway is smooth but short, you may have the choice of what to run
into at a reduced speed. If it's an off-runway situation, you'll be
touching down at whatever flying speed, and encountering surface
irregularities at higher speeds.

It's easy for folks to only consider some emergencies when justifying their
risk profiles. Of course, I've never done that :-)

Ed Wischmeyer

[Richard Riley]

On 19 May 2004 07:52:18 -0700, (Paul Lee)
wrote:

:KLS website is gone because KLS is in process of changing name. KLS
:was a partnership and one of the partners left. The new name
:is Advanced Composite Design, Inc. KLS has also just finished developing
:a new desing of a large plane (tested and flying). Thats explained at m y
:website http://www.abri.com/sq2000

Stan's run through another partnership? That's about on schedule,
they last 3-4 years or so in this business. So that's Shirl, Kurt and
now Keith.
:
:I just came back from SQ2000 factory training.
:I haven't tried the factory model to Vne. I was mainly interested in
:take off and landing skills. But Stan indicated he achieves 230mph
:cruise.

It wouldn be it would be Vmax, not Vne, - maximum cruising speed, not
never exceed speed. I'd be *very* surprised if Stan was getting that
- 360 Long EZ's do 230-235 mph wide open. The 360 Berkut does
235-240, and that's with half the fuselage, and a couple of hundred
pounds less than the Speed Queen. He's probably around 220, a few mph
faster than the Cozy.

:But isn't Cozy IV fixed main gear? That would explain some of
:the difference.

As I said in my previous post, it would explain *some* of the
difference, but not much. A well faired gear produces as much drag as
a couple of whip antennas of the same length.
:
:> Landing that fast increases risk, limits the airports you can land at,
:> and increases wear. .........
:
:True. But in my case we have two 6800 x 150 foot runways. In SQ2000
:factory flight training I was instructed to touchdown at 90MPH and did
:consistently and the bird exhibited no problem behaviour. I am sure
:that after I get a lot more hours experience like you or Stan, I'll be
:able to cut the landing speed. If you are around Pierre, SD you are
:welcome to check out my bird.

The aircraft is capable of a lower landing speed (or it isn't, but it
probably is). If it is, then you can certainly change your mind and
land slower. The thing that worries me is that you're being trained
to land that fast, and being told that it's a good idea.

:
:Interestingly, while on the subject of safety, about 6 weeks ago, the
:KLS SQ2000 came down in a storm and busted the landing gear. It slid
:down the runway and into a ditch. No injuries, it did not flip over,
:and surprisingly the damage was mainly to the landing gear and the
:prop (toothpicks all over) - very little other damage.

Composite airplanes are surprisingly strong. I know of one that was
flipped over by a dust devil on final, hit inverted and tumbled. The
pilot broke his leg, the passenger got a cut on his forhead. Another
lost it's engine on final, went through trees, touched down on a
freeway going the wrong way and went head on with a car. The pilot
was completely unhurt, though every part of the airplane was broken.

Any idea why the airplane ripped out it's gear? I know it was in a
storm, but did he catch the gear on something on touchdown? Excessive
sink rate? The gear should be able to take 3-4 G's without departing
the aircraft,

[Richard Riley]

On Wed, 19 May 2004 09:02:25 -0700, Ed Wischmeyer
> wrote:

:It's easy for folks to only consider some emergencies when justifying their
:risk profiles. Of course, I've never done that :-)
:
:Ed Wischmeyer

And you've never seen any emergencies, have you Ed? No blown tires,
hung gear, drug wingtips, eaten valves, frozen control systems,
clogged fuel filters. Aviation is like WestWord, where nothing can
possibly go worng.

[Jim-Ed Browne]

"Pete Schaefer" > wrote in message news:<Btqpc.53022$536.9082680@attbi_s03>...
> Landing speeds are a big driver for the amount of injury. I think that the
> FAA has a lot of data on this. Can't think of a reference off-hand, but you
> can search the NTSB site. But anyway, here's the math: KE = (1/2)mv^2. The
> basic conclusion is that accidents occuring at lower landing speeds do less
> damage. This was a driver for the design of the RV series aircraft. If you
> want safety, get something with STOL capability, make sure there's nothing
> in the cockpit that's going to smack you in the back of the head if you
> screw up, then practice, practice, practice (with an instructor until you
> feel confident).....then practice some more. Avoid low-level aerobatics
> until you're a really ****-hot pilot.
>
> You really need to forget about structural protection in a home-built. The
> key is to prevent (by flight procedure, pilot skill and knowledge, and by
> appropriate vehicle design) accidents from happening in the first place.

Is this because none of the ones available as designs currently have
any, or because you feel it's not feasible, or because....exactly why?
Race cars go faster on the ground than some homebuilts will _straight
down_ and, Dale Earnhardt aside, usually people go in the wall and
walk out (or get pulled out by the crash wagon crew).

I recall that the P-51's designer, Dutch Kindelberger, designed the
cockpit area as the toughest structure, so everything else would
crumple around the pilot and provide protection from the sudden
impact. Is this somehow no longer feasible?

[Pete Schaefer]

Hey Jim-Ed:


"Jim-Ed Browne" > wrote in message
om...
> Is this because none of the ones available as designs currently have
> any, or because you feel it's not feasible, or because....exactly why?

I've never looked at any airplane designs that have such features. There is
a huge price to pay in terms of weight, required power and such to provide
pilot protection. Drives up cost a ton, and makes operations more
expensive.

Keep in mind that crumple zones are only really for front impact, too.

> Race cars go faster on the ground than some homebuilts will _straight
> down_ and, Dale Earnhardt aside, usually people go in the wall and

They have requirements for driver protection. And they have huge budgets to
work with. I don't know about about NASCAR, but, to get the sign-off to
race, the CART guys have to slam a couple of chassis into a wall to show
that the tub holds together. Expensive, expensive, expensive.

> I recall that the P-51's designer, Dutch Kindelberger, designed the
> cockpit area as the toughest structure, so everything else would
> crumple around the pilot and provide protection from the sudden
> impact. Is this somehow no longer feasible?

Sure, it's feasible, but it's expensive. How many airframes do you want to
build for the purpose of destroying them to prove the design? Then there's
costs of test facilities. What's the cost in weight, performance, etc.? How
much is it going to cost to design, model, and test? If you see a couple of
zeros being added on to the total cost to build and get the FAA to sign it
off, then you're probably getting a realistic picture.

Even if you could afford to buy one, operation costs of a P-51 is probably
well beyond the average budget of the typical home-builder. Besides, the
P-51 was designed to go to war and get shot at, not for $100 hamburgers.

I guess the question I have is this: How much are you willing to spend to
get an airplane that protects you in case of a crash? If you've got
millions to spend, then you can probably get what you want. But on a $50k
home-built? Forget it. Maybe a certified commercial manufacturer would have
the resources to pursue safety features like this, but I would find it
surprising if people would be willing to fork out the extra bucks for it,
given that the costs would have to be recovered through the sale of a
relatively small number of airplanes.

There are probably much better approaches to achieving leaps in aviation
safety without doing anything about crashworthiness improvments. Think
about the safety improvements you'd get just by having a more reliable
powerplant and fuel delivery system. Think about potential improvements
from sophisticated engine health monitoring (condition-based
maintenance....catch and repair faults before they become
catastrophic...there are some really nice products out there right now)?
Then there are potential benefits for IFR/night flight using synthetic
vision to prevent spatial disorientation. These kinds of improvments might
cost thousands of dollars to the consumer, falling in the range of what is
affordable to the typical RV builder at least.

Anyway, just some things to think about. If you dig around for some of the
data on NASA's General Aviation Revitalization effort (no longer going on, I
think), you can find more comprehensive info on these topics.


Pete

P.S. Just to qualify my views - I'm not an airframe designer, but I do work
in aircraft development. I'm a flight controls engineer (meaning that I'm
one of the guys who's found ways to drive up the costs of an airplane
without driving the weight up) with Lockheed in Palmdale, CA. While I don't
work directly with these design/development trades, I am regularly exposed
to the issues and compromises that they bring up. So...knowledgable, but
not an expert.

[Paul Lee]

Richard Riley > wrote in message >...

>.................................... When I say exactly, I mean
> exactly - to the fraction of an inch in planform, with the same
> templates, with the same modified Eppler airfoil on the mains, and the
> same Roncz 1145 MS on the canard.............

Rich,

There is a curiosity that I found about the SQ2000. When Stan
demonstrated stall, the plane did not dip and dive (bobing) like
typical canards, but simply descended at a steady rate - or climbed at
a steady rate in a power stall. The canard just shakes slightly
almost like conventional aircraft before a stall - i.e. it failed
gradually and not suddenly. The feature shure wis handy if you
inadvertendly land too slow - it would descend at steady rate and not
dive into the ground.

I haven't seen this behaviour mentioned for other canards and Stan would
not tell me how he got that. Are there other canard designs that do
that? Do you know how it works?

---------------------------------------------------
Paul Lee, SQ2000 canard: http://www.abri.com/sq2000

[[email protected]]

On 19 May 2004 12:03:24 -0700, (Jim-Ed Browne)
wrote:

> I recall that the P-51's designer, Dutch Kindelberger, designed the
>cockpit area as the toughest structure, so everything else would
>crumple around the pilot and provide protection from the sudden
>impact. Is this somehow no longer feasible?

You do? References please. I've studied that fighter for years and
this is the first I've ever heard of Kindelberger designing the
cockpit like a modern car is designed.

Thanks, Corky Scott

[Bill Daniels]

"Pete Schaefer" > wrote in message
news:DQOqc.80298$iF6.6816727@attbi_s02...
> Hey Jim-Ed:
>
>
> "Jim-Ed Browne" > wrote in message
> om...
> > Is this because none of the ones available as designs currently have
> > any, or because you feel it's not feasible, or because....exactly why?
>
> I've never looked at any airplane designs that have such features. There
is
> a huge price to pay in terms of weight, required power and such to provide
> pilot protection. Drives up cost a ton, and makes operations more
> expensive.
>
> Keep in mind that crumple zones are only really for front impact, too.
>
> > Race cars go faster on the ground than some homebuilts will _straight
> > down_ and, Dale Earnhardt aside, usually people go in the wall and
>
> They have requirements for driver protection. And they have huge budgets
to
> work with. I don't know about about NASCAR, but, to get the sign-off to
> race, the CART guys have to slam a couple of chassis into a wall to show
> that the tub holds together. Expensive, expensive, expensive.
>
> > I recall that the P-51's designer, Dutch Kindelberger, designed the
> > cockpit area as the toughest structure, so everything else would
> > crumple around the pilot and provide protection from the sudden
> > impact. Is this somehow no longer feasible?
>
> Sure, it's feasible, but it's expensive. How many airframes do you want to
> build for the purpose of destroying them to prove the design? Then there's
> costs of test facilities. What's the cost in weight, performance, etc.?
How
> much is it going to cost to design, model, and test? If you see a couple
of
> zeros being added on to the total cost to build and get the FAA to sign it
> off, then you're probably getting a realistic picture.
>
> Even if you could afford to buy one, operation costs of a P-51 is probably
> well beyond the average budget of the typical home-builder. Besides, the
> P-51 was designed to go to war and get shot at, not for $100 hamburgers.
>
> I guess the question I have is this: How much are you willing to spend to
> get an airplane that protects you in case of a crash? If you've got
> millions to spend, then you can probably get what you want. But on a $50k
> home-built? Forget it. Maybe a certified commercial manufacturer would
have
> the resources to pursue safety features like this, but I would find it
> surprising if people would be willing to fork out the extra bucks for it,
> given that the costs would have to be recovered through the sale of a
> relatively small number of airplanes.
>
> There are probably much better approaches to achieving leaps in aviation
> safety without doing anything about crashworthiness improvments. Think
> about the safety improvements you'd get just by having a more reliable
> powerplant and fuel delivery system. Think about potential improvements
> from sophisticated engine health monitoring (condition-based
> maintenance....catch and repair faults before they become
> catastrophic...there are some really nice products out there right now)?
> Then there are potential benefits for IFR/night flight using synthetic
> vision to prevent spatial disorientation. These kinds of improvments
might
> cost thousands of dollars to the consumer, falling in the range of what is
> affordable to the typical RV builder at least.
>
> Anyway, just some things to think about. If you dig around for some of
the
> data on NASA's General Aviation Revitalization effort (no longer going on,
I
> think), you can find more comprehensive info on these topics.
>
>
> Pete
>
> P.S. Just to qualify my views - I'm not an airframe designer, but I do
work
> in aircraft development. I'm a flight controls engineer (meaning that I'm
> one of the guys who's found ways to drive up the costs of an airplane
> without driving the weight up) with Lockheed in Palmdale, CA. While I
don't
> work directly with these design/development trades, I am regularly exposed
> to the issues and compromises that they bring up. So...knowledgable, but
> not an expert.
>
>

Yes, there are some negatives. However, re-enforced cockpits are becoming
the norm in sailplanes. Carbon-Kevlar composites provide a lot of
protection for the weight. Gliders land a lot more slowly than even RV's
but they are expected to land off airports without damage. If you
incorporate a ballistic parachute, re-enforced cockpits are required.

No amount of strengthening of the cockpit will save the pilot under all
circumstances but it might make a difference in some situations. A modest
amount seems a good idea.

Bill Daniels

[Kevin Horton]

On Wed, 19 May 2004 13:49:13 -0700, Paul Lee wrote:

> Richard Riley > wrote in message
> >...
>
>>.................................... When I say exactly, I mean
>> exactly - to the fraction of an inch in planform, with the same
>> templates, with the same modified Eppler airfoil on the mains, and the
>> same Roncz 1145 MS on the canard.............
>
> Rich,
>
> There is a curiosity that I found about the SQ2000. When Stan demonstrated
> stall, the plane did not dip and dive (bobing) like typical canards, but
> simply descended at a steady rate - or climbed at a steady rate in a power
> stall. The canard just shakes slightly almost like conventional aircraft
> before a stall - i.e. it failed gradually and not suddenly. The feature
> shure wis handy if you inadvertendly land too slow - it would descend at
> steady rate and not dive into the ground.
>
> I haven't seen this behaviour mentioned for other canards and Stan would
> not tell me how he got that. Are there other canard designs that do that?
> Do you know how it works?
>
> --------------------------------------------------- Paul Lee, SQ2000
> canard: http://www.abri.com/sq2000


I'm not Richard Riley, but I'll pipe up anyway.

I'm betting that there wasn't enough pitch authority to get the angle of
attack high enough to stall the canard. The situation might be quite
different if the CG was further aft (i.e. pilot only, or with pax in back).

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

[nauga]

Kevin Horton wrote...

> I'm not Richard Riley, but I'll pipe up anyway.

It's getting crowded in Richard and Paul's phone booth <g>

> I'm betting that there wasn't enough pitch authority to get the angle of
> attack high enough to stall the canard. The situation might be quite
> different if the CG was further aft (i.e. pilot only, or with pax in
back).

You beat me to it.

Dave 'control power' Hyde

[Paul Lee]

Hey,

I'd taken you up on that just few weeks ago. But now I have
4 hours on a SQ2000 already. I read all of your flight test
report previously from your website trying to get as much info
as possible. But hey, I might fly in and compare things anyway.

As I have mentioned already to somebody else, we have two
6800 x 150 ft runways here and I am sure after I get lot
more practice I can do it at slower speeds.

"Marc J. Zeitlin" > wrote in message news:<TMAqc.75739$536.12331982@attbi_s03>...

> ................... I'll be happy to check you out in my COZY MKIV
> (left seat, if you'd like) if you'd like to come to MA before your first
> flight, so you can see the difference. Let me know.

[John]

(Paul Lee) wrote:

Thats explained at my
>website http://www.abri.com/sq2000

And now to open another can of worms, an IVO plastic prop on a 220 hp
pusher??? I thought this was a no-no for pushers. Your thoughts plz.
Other's thoughts plz. Thanks.

[DEATH]

>
> I hope I don't seem paranoid, but assuming I'm likely to be flying for 50
> years, even accident rates down in the low percents seem quite alarming.
>

Assuming you plan on driving or even walking across a roadway in the same 50
years, accident rates are even more alarming.

[jls]

"Kevin Horton" > wrote in message >
> I'm not Richard Riley,

God be thanked.

[Pete Schaefer]

It seems to me that such measures would be more important for a sailplane.
After all, you can't exactly go around if you botch the approach.


"Bill Daniels" > wrote in message
news:KTPqc.80525$iF6.6835883@attbi_s02...
> Yes, there are some negatives. However, re-enforced cockpits are becoming
> the norm in sailplanes. Carbon-Kevlar composites provide a lot of
> protection for the weight. Gliders land a lot more slowly than even RV's
> but they are expected to land off airports without damage. If you
> incorporate a ballistic parachute, re-enforced cockpits are required.

[Vaughn]

"Pete Schaefer" > wrote in message
news:0cTqc.81388$iF6.6927599@attbi_s02...
> It seems to me that such measures would be more important for a sailplane.
> After all, you can't exactly go around if you botch the approach.

Not necessarily true, but also virtually never necessary. A good sailplane
gives you amazing glideslope control. With the spoilers fully deployed, I am
literally standing on the rudder pedals in some sailplanes approaching the
runway like a nicely controllable anvil; yet you can close them at any time to
instantly regain your full glide ratio, or modulate them anywhere in between.
It works! Just don't get low, slow, and downwind.

After years as a glider-guider (or a "dope on a rope" if you prefer) I have
finally taken up powered flight, and I am not at all sure that I have truly
internalized the concept that go-arounds are now an option.

Vaughn

[Richard Riley]

On 19 May 2004 12:49:13 -0700, (Paul Lee)
wrote:

:Richard Riley > wrote in message >...
:
:>.................................... When I say exactly, I mean
:> exactly - to the fraction of an inch in planform, with the same
:> templates, with the same modified Eppler airfoil on the mains, and the
:> same Roncz 1145 MS on the canard.............
:
:Rich,
:
:There is a curiosity that I found about the SQ2000. When Stan
:demonstrated stall, the plane did not dip and dive (bobing) like
:typical canards, but simply descended at a steady rate - or climbed at
:a steady rate in a power stall. The canard just shakes slightly
:almost like conventional aircraft before a stall - i.e. it failed
:gradually and not suddenly. The feature shure wis handy if you
:inadvertendly land too slow - it would descend at steady rate and not
:dive into the ground.
:
:I haven't seen this behaviour mentioned for other canards and Stan would
:not tell me how he got that. Are there other canard designs that do
:that? Do you know how it works?

What you saw is basically how the EZ canard pushers behave. The
canard bob is never large. A lot of things affect it - density
altitude, humidity, how many bugs are on the leading edge, CG, the
shape of the canard and exact placement of the elevators in
relationship to the rest of the canard. If the entire surface is
stalling at exactly the same time, the bob is more noticeable. If
parts of it hold on slightly longer than other parts, the oscillation
will be smaller.

When Rick was doing the Berkut airshow, one of his moves was a low
speed level pass, showing the canard bob at minimum airspeed. But the
real canard bob couldn't be seen from the ground - it could barely be
seen from inside the plane. So he worked the elevator up and down to
bob the nose.

I've never seen a canard let go and "dive into the ground" - the nose
always stays well above the horizon. But if you're power off, your
decent rate at canard bob is much higher than it would be at best
glide.

[Bill Daniels]

"Vaughn" > wrote in message
...
>
> "Pete Schaefer" > wrote in message
> news:0cTqc.81388$iF6.6927599@attbi_s02...
> > It seems to me that such measures would be more important for a
sailplane.
> > After all, you can't exactly go around if you botch the approach.
>
> Not necessarily true, but also virtually never necessary. A good
sailplane
> gives you amazing glideslope control. With the spoilers fully deployed, I
am
> literally standing on the rudder pedals in some sailplanes approaching the
> runway like a nicely controllable anvil; yet you can close them at any
time to
> instantly regain your full glide ratio, or modulate them anywhere in
between.
> It works! Just don't get low, slow, and downwind.
>
> After years as a glider-guider (or a "dope on a rope" if you prefer) I
have
> finally taken up powered flight, and I am not at all sure that I have
truly
> internalized the concept that go-arounds are now an option.
>
> Vaughn
>
Don't forget and land that Cessna in the grass alongside the runway. It's
REALLY hard to explain that.

BTW, A glider can do a LOT more than most people think. A pilot from Reno
flew non-stop to Steamboat Springs, Colorado last month - about 843nm.

A story.

Long ago I was entering the pattern with a sailplane at a one runway tower
controlled airport in Texas. While I was on downwind, a Piper blew a tire
on the runway, blocking it. The tower asked me nervously where I could
land. I had noticed that there was weak lift in the pattern so I replied,
"no problem, I can hold".

It took about 15 minutes to move the Piper clear of the active. Meantime, I
slowly and silently circled at 1000' AGL. Each time I came around, I could
see the faces of the tower personnel pressed against the glass watching me.

When the landing clearance came, I landed long, took a high speed exit that
led to the transit parking area and stopped on a tiedown. Some local folks
bought me dinner and beer that night while I waited for my crew. I think
there were a few new glider pilots that came out of that.

Bill Daniels

[Paul Lee]

John > wrote in message >...
> (Paul Lee) wrote:
>
> Thats explained at my
> >website http://www.abri.com/sq2000
>
> And now to open another can of worms, an IVO plastic prop on a 220 hp
> pusher??? I thought this was a no-no for pushers. Your thoughts plz.
> Other's thoughts plz. Thanks.

No problem. There are a number of Velocities and other canards using IVO props.
See http://www.ida.net/biz/arlfrd/ (Crawford was a very experienced builder)
and http://www.lavoiegraphics.com/velocityrg/

I think you are confusing the triblade IVO problem with the giant Lycoming
IO-360 four banger issue. There are some problems with IO-360 engine resonance
and the three blade props particularly. But a six cylinder is much smoother,
and particularly Franklin is smooth - fluid filled flywheel to dampen out
vibration. The issue is not restricted to IVO but to most triblade props
on large four bangers. In fact that is one reason I chose Franklin 6,
its smoothnes. Large four banger vibration is not just a problem for props,
but for the rest of the aircraft and certain design care has to be taken to
cut down transmitted vibration.

[Ernest Christley]

Pete Schaefer wrote:
> Hey Jim-Ed:
>
>
> "Jim-Ed Browne" > wrote in message
> om...
>
>> Is this because none of the ones available as designs currently have
>>any, or because you feel it's not feasible, or because....exactly why?
>
>
> I've never looked at any airplane designs that have such features. There is
> a huge price to pay in terms of weight, required power and such to provide
> pilot protection. Drives up cost a ton, and makes operations more
> expensive.
>

Don't mean to tell you your business, but....bulls417!!

See my website for PICTURES of proof. Crumple zones are not only
feasible, reliable, and light, but they've been flying for over 40years.

> Sure, it's feasible, but it's expensive. How many airframes do you want to
> build for the purpose of destroying them to prove the design? Then there's
> costs of test facilities. What's the cost in weight, performance, etc.? How
> much is it going to cost to design, model, and test? If you see a couple of
> zeros being added on to the total cost to build and get the FAA to sign it
> off, then you're probably getting a realistic picture.
>

No extra cost or weight, and why would you get the FAA to sign off on a
homebuilt aircraft design? It won't cost any more to design, model and
test than any other homebuilt design. Why would you need to do
destructive testing? Do I have to break my wings to prove they will
hold me up in flight?

> I guess the question I have is this: How much are you willing to spend to
> get an airplane that protects you in case of a crash? If you've got
> millions to spend, then you can probably get what you want. But on a $50k
> home-built? Forget it. Maybe a certified commercial manufacturer would have
> the resources to pursue safety features like this, but I would find it
> surprising if people would be willing to fork out the extra bucks for it,
> given that the costs would have to be recovered through the sale of a
> relatively small number of airplanes.
>

My goal is to stay well under $20k. One builder lost his engine and
didn't make the airport. Buried his Delta in a barnyard silo after
passing it through a bale of hay. Walked away from it. If you can keep
the landing to an acute angle crumple zones WILL help.

> There are probably much better approaches to achieving leaps in aviation
> safety without doing anything about crashworthiness improvments. Think
> about the safety improvements you'd get just by having a more reliable
> powerplant and fuel delivery system. Think about potential improvements
> from sophisticated engine health monitoring (condition-based
> maintenance....catch and repair faults before they become
> catastrophic...there are some really nice products out there right now)?
> Then there are potential benefits for IFR/night flight using synthetic
> vision to prevent spatial disorientation. These kinds of improvments might
> cost thousands of dollars to the consumer, falling in the range of what is
> affordable to the typical RV builder at least.
>

From the statistics, the fuel delivery reliability rest most directly
on the pump in the fuel truck back at the airport. There ain't any
hardware that can fix that fault. It's a software problem 8*)

As for the rest of that...now who's talking about spending big dollars?
Crashworthiness should be part of the primary structure. Not a heavy,
expensive afterthought.

> Anyway, just some things to think about. If you dig around for some of the
> data on NASA's General Aviation Revitalization effort (no longer going on, I
> think), you can find more comprehensive info on these topics.
>
>
> Pete
>
> P.S. Just to qualify my views - I'm not an airframe designer, but I do work
> in aircraft development. I'm a flight controls engineer (meaning that I'm
> one of the guys who's found ways to drive up the costs of an airplane
> without driving the weight up) with Lockheed in Palmdale, CA. While I don't
> work directly with these design/development trades, I am regularly exposed
> to the issues and compromises that they bring up. So...knowledgable, but
> not an expert.
>
>

When I sit in my incomplete project, I can look around at all the steel
that has to bend before the outside gets to me, I can imagine all the
fiberglass that will have to give way, and even if I'm no safer than in
the aluminum can I trained in, I certainly feel that way. There are not
any electronics or flight systems that will ever make me feel safer than
several feet of protection between me and the hard stuff.


--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[anonymous coward]

On Wed, 19 May 2004 19:46:43 +0000, Pete Schaefer wrote:

> Hey Jim-Ed:
>
>
> "Jim-Ed Browne" > wrote in message
> om...
>> Is this because none of the ones available as designs currently have
>> any, or because you feel it's not feasible, or because....exactly why?
>
> I've never looked at any airplane designs that have such features. There is
> a huge price to pay in terms of weight, required power and such to provide
> pilot protection. Drives up cost a ton, and makes operations more
> expensive.

Most paraglider pilots have a harness that includes some 'crushables' to
protect their backs if their canopies collapse at low-level. Recently the
tide has turned against rigid harnesses with carbon-fiber backplates.
These used to be popular on the grounds that they would reinforce the
backbone - now people believe that they are so rigid they can concentrate
the forces on small sections of the spine (typically the lower lumbar
vertebrae) and _increase_ the risk of spinal injuries. Now people prefer
airbags that let the air out gradually through the seams during an impact
(to prevent recoil). Alternatively some harnesses use foam to spread
impact forces over the whole area of the back. There's little consensus
about how well they work, but little doubt that they can provide an 'edge'.

This is just a longwinded way of saying 'I don't see why passive safety
should necessarily be heavy and expensive' It might be as little as 2" of
foam and a more ergonomically shaped seat.

To put it another way, I weigh 20kg less than average. I wonder how much
energy that weight of intelligently positioned crushable foam could
absorb? Or even a small fraction of that weight.

> Keep in mind that crumple zones are only really for front impact, too.

No reason why. Actually, I'd have thought it should be easier to design
passive protection into an aircraft because side and rear impacts are
probably less common.

I have heard something in the New-Scientist about weakened floors in
airliners that could crumple and save people's backs when planes crash
with too high a descent rate. I also heard that in one frontal collision
in an airliner, many lives were needlessly lost because many people's legs
swung forwards under the seat infront and fractured around the shins. This
meant that they couldn't leave the accident site, even though there was
time. Now, most airline seats have soft edges around the relevant parts of
the seats.

None of this directly applicable to GA.

AC

[anonymous coward]

On Wed, 19 May 2004 20:03:57 -0400, DEATH wrote:

>
>>
>> I hope I don't seem paranoid, but assuming I'm likely to be flying for 50
>> years, even accident rates down in the low percents seem quite alarming.
>>
>
> Assuming you plan on driving or even walking across a roadway in the same 50
> years, accident rates are even more alarming.

Really?

[Pete Schaefer]

"Ernest Christley" > wrote in message
. com...
> See my website for PICTURES of proof. Crumple zones are not only
> feasible, reliable, and light, but they've been flying for over 40years.

There's a lot of stuff on your site. I didn't see anything about crumple
zones. Please provide pointers to what you're talking about. I kept flipping
through your pages, doing searches for "crumple"....no hits.

> test than any other homebuilt design. Why would you need to do
> destructive testing? Do I have to break my wings to prove they will
> hold me up in flight?

As far as I know, crumple zones are not reusable. Isn't that the point of
them? How can you test the design if you don't do it destructively? Am I
missing something here? Or are you saying that analysis is sufficient? Or
are you confusing crumple zones with something else? I don't get your
analogy, either. You test a wing structure by putting it under load and
showing it holds; you test an energy dissipation feature like a crumple zone
by subjecting it to an impact and showing that it crumples by the amount
predicted.

> the landing to an acute angle crumple zones WILL help.

I didn't see the crumple zone features of the Delta that you are refering
to.

> Crashworthiness should be part of the primary structure. Not a heavy,
> expensive afterthought.

ALL of the crashworthiness considerations I've ever seen have been the usual
"this is the max expected design load, so make it strong enough to withstand
XX times that". Often, there is additional strength in components that
protect the pilot. But that's different than crumple zones.

> When I sit in my incomplete project, I can look around at all the steel

Fine. If that gives you a warm fuzzy, then good for you. Me? I'll place my
emphasis on accident prevention - both by design, training, and proper
preparation.

> There are not any electronics or flight systems that will ever make me
feel safer than
> several feet of protection between me and the hard stuff.

Not even an angle-of-attack sensor? Dang. Given that they are available, I
wouldn't consider building a new plane without one. But your Deltas don't
have enough elevon authority to reach CLmax, so that's probably not an issue
for you.

[Pete Schaefer]

"anonymous coward" > wrote in message
.
> This is just a longwinded way of saying 'I don't see why passive safety
> should necessarily be heavy and expensive' It might be as little as 2" of
> foam and a more ergonomically shaped seat.

But that's not a feature of the basic airframe design, which is the subject
that we're addressing here. I would believe that crushable foam, as is used
in motorcycle & bicycle helmets can probably, under certain circumstances,
make the difference between a sore back and weeks in the hospital.
Likewise, seating position has a lot to do with what kind of injuries you're
likely to encounter.

> To put it another way, I weigh 20kg less than average. I wonder how much
> energy that weight of intelligently positioned crushable foam could
> absorb? Or even a small fraction of that weight.

Probably quite a bit. But where would you put it? Are you talking about the
possibility of building a lightweight foam tub to put the pilot it? There
might be some possibilities there, but keep in mind that foam only really
helps you with compression loads.

[Richard Riley]

On Wed, 19 May 2004 09:07:53 -0700, Richard Riley
> wrote:

:On Wed, 19 May 2004 09:02:25 -0700, Ed Wischmeyer
> wrote:
:
::It's easy for folks to only consider some emergencies when justifying their
::risk profiles. Of course, I've never done that :-)
::
::Ed Wischmeyer
:
:And you've never seen any emergencies, have you Ed? No blown tires,
:hung gear, drug wingtips, eaten valves, frozen control systems,
:clogged fuel filters. Aviation is like WestWord, where nothing can
:possibly go worng.

Ooops. Sorry, Ed, had a short brain fart there, and had you mixed up
with Cy Galley. Never mind.

[anonymous coward]

On Thu, 20 May 2004 06:03:49 +0000, Pete Schaefer wrote:
>
> "anonymous coward" > wrote in message
> .
>> This is just a longwinded way of saying 'I don't see why passive safety
>> should necessarily be heavy and expensive' It might be as little as 2" of
>> foam and a more ergonomically shaped seat.
>
> But that's not a feature of the basic airframe design, which is the subject
> that we're addressing here.

Does it really matter?

> I would believe that crushable foam, as is used
> in motorcycle & bicycle helmets can probably, under certain circumstances,
> make the difference between a sore back and weeks in the hospital.
> Likewise, seating position has a lot to do with what kind of injuries you're
> likely to encounter.
>
>> To put it another way, I weigh 20kg less than average. I wonder how much
>> energy that weight of intelligently positioned crushable foam could
>> absorb? Or even a small fraction of that weight.
>
> Probably quite a bit. But where would you put it? Are you talking about the
> possibility of building a lightweight foam tub to put the pilot it?

That was one thing I had in mind. But all I can imagine this would
protect against would be loads on the spine if you hit the ground
horizontally and with a high rate of descent. Incidentally (and as you can
probably tell) I'm not an engineer, but I think I have enough engineer's
genes to realise that this wouldn't necessarily be simple. For example I'm
guessing you would need quite soft foam, otherwise it wouldn't deform
at all (loads spread over too large an area). Then you have the problem
that it's easy to put your foot through it, so you have to cover it with
something hard. And so on...

> There might be some possibilities there, but keep in mind that foam only
> really helps you with compression loads.

Another idea was putting a big chunk of foam at the front of the aircraft
to slow the deacceleration if you hit something frontways. Say you have to
land out, and hit a stone wall in the middle of the field (lots round
here). The pilot would pull against the harness straps (I think I'm right
in saying they would stretch to absorb some of the energy) but the
airframe may break. Perhaps a cubic foot of harder, crushable foam in the
nosecone could reduce peak loads on the airframe and spread them more
evenly, allowing it to remain intact?

I'd be interested to hear more about these gliders' reinforced cockpits.
Perhaps all this speculation has been despeculated already?

AC

[Pete Schaefer]

"anonymous coward" > wrote in message
. ..
> > But that's not a feature of the basic airframe design, which is the
subject
> > that we're addressing here.
> Does it really matter?

I guess it's pertinent; it's all about risk mitigation. But pilot protection
(beyond accident prevention) starts with the airframe design. Having a
crushable foam seat bottom won't matter much if you end up with the engine
in your lap.

> protect against would be loads on the spine if you hit the ground
> horizontally and with a high rate of descent. Incidentally (and as you can

Yes, but a hard landing might be the most important design point. How many
ground loops begin with a pilot landing hard and losing control?

> guessing you would need quite soft foam, otherwise it wouldn't deform

The foams they use for helmets are pretty hard. They won't deform until you
hit a threshhold. You don't want something that will compress under normal
loads.

> Another idea was putting a big chunk of foam at the front of the aircraft
> to slow the deacceleration if you hit something frontways. Say you have to

We could be talking about a lot of energy. Might require a lot of foam.

> airframe may break. Perhaps a cubic foot of harder, crushable foam in the
> nosecone could reduce peak loads on the airframe and spread them more

Where in the nose would you put it? I was thinking of maybe something behind
the instrument panel, maybe attached to the firewall. Speaking of fire....I
think I have an old bicycle helmet laying around. Maybe I'll put a match to
it. Anyway, I'm sure there's data available on foams currently in use.

> I'd be interested to hear more about these gliders' reinforced cockpits.
> Perhaps all this speculation has been despeculated already?

Perhaps. I would think that you'd have an easier time with composites in
building a really stout shell around the pilot. Just a couple more plys of
glass/carbon/kevlar/whatever..... It could give more protection than a metal
design. Composites seem to be easier to design with for energy-dissipation.
You can't tear them easily. The tubs that F-1 drivers sit in are all
carbon, with the outer structure designed to shred nicely if the car hits a
wall at high speed. I have a friend who used to work for Dan Gurney in
Anaheim, and he gave me an insiders tour. He showed me the chassis that they
had slammed. The inside of the tub looked new, but everything outside it
was just shredded. Airplanes don't give anywhere near that level of
protection.

[[email protected]]

On Thu, 20 May 2004 03:25:58 GMT, Ernest Christley
> wrote:

>
>Don't mean to tell you your business, but....bulls417!!
>
>See my website for PICTURES of proof. Crumple zones are not only
>feasible, reliable, and light, but they've been flying for over 40years.

Where on your website?

Corky Scott

[Paul Lee]

Richard Riley > wrote in message >...
>....
> Any idea why the airplane ripped out it's gear? I know it was in a
> storm, but did he catch the gear on something on touchdown? Excessive
> sink rate? The gear should be able to take 3-4 G's without departing
> the aircraft,

It didn't actually rip out. They hit the gear sideways in the storm.
Its not a fixed gear and the lower brace pivot pin sheared and of
course the whole thing folded up under the fuselage then. You can see
how it is contructed at http://www.abri.com/sq2000/rg06.jpg

Its similar to Infinity gear design http://www.infinityaerospace.com/infgear.htm

Stan has since then reinforced the pin mountings. And I am modifying mine
in a different way.

[Paul Lee]

Richard Riley > wrote in message >...
> On 19 May 2004 07:52:18 -0700, (Paul Lee)
> wrote:
>
> Stan's run through another partnership? That's about on schedule,
> they last 3-4 years or so in this business. So that's Shirl, Kurt and
> now Keith.
> ...

The new arrangement is a corporation and not a partnership. That's the
way it should have been in the first place so that there is no need
for change of name in case somebody wants out - they just sell their
part of the shares. I think initially the partners just really wanted
each to get a SQ2000 copy. But I suppose after a few years a person is
not interested in the daily operation of the factory. I guess I am
more familiar with the case because I have been in touch getting
building support from KLS over almost 3 years.

[Jim-Ed Browne]

> Not necessarily true, but also virtually never necessary. A good sailplane
> gives you amazing glideslope control. With the spoilers fully deployed, I am
> literally standing on the rudder pedals in some sailplanes approaching the
> runway like a nicely controllable anvil; yet you can close them at any time to
> instantly regain your full glide ratio, or modulate them anywhere in between.
> It works! Just don't get low, slow, and downwind.
>
> After years as a glider-guider (or a "dope on a rope" if you prefer) I have
> finally taken up powered flight, and I am not at all sure that I have truly
> internalized the concept that go-arounds are now an option.

Wolfgang pointed out in the 1940s that most lightplanes suffered not
from too poor a glide ratio but one that was too good-making power off
approaches challenging when it has to be done for real.

Most any airplane can be deadsticked-it was done with the F-104
several times, the most famous being the RCAF pilot who executed a
perfect rollout in the middle of a huge frozen lake, rolled to a stop,
got out-then panicked at being on the ice alone,climbed back in the
cockpit and shot himself dead. (The airplane was fixed and flown out.)
The X-1, X-15, and other rocket planes landed deadstick every time and
so does the Space Shuttle.

(Exception-the T-38 and a couple other jet twins with irreversible
hydraulic flight controls and no RAT or standby electric or hydrazine
pump. The USAF justifies this by saying if both engines quit we want
the pilots to punch out,it's safer.)

Today, light planes-particularly the ones that crash with six people
and get the manufacturer sued-are always flown with power-on
approaches so the obsolete museum piece forward of the firewall
doesn't get shock cooled. Then said museum piece quits.... This is an
example of "organized stupidity". An effective speedbrake/spoiler
system would have prevented, in my opinion and in that of many more
well qualified people than myself, the majority of fatal Bonanza
crashes in the last 40 years.

Has experimental aviation learned from this? Well, not yet, but
there's still hope.

[Ernest Christley]

Pete Schaefer wrote:
> "Ernest Christley" > wrote in message
> . com...
>
>>See my website for PICTURES of proof. Crumple zones are not only
>>feasible, reliable, and light, but they've been flying for over 40years.
>
>
> There's a lot of stuff on your site. I didn't see anything about crumple
> zones. Please provide pointers to what you're talking about. I kept flipping
> through your pages, doing searches for "crumple"....no hits.

Does it have to be labeled "Crumple Zone" to work?
No, seriously, after looking at the pictures from the perspective of
someone who doesn't look at the plane everyday, the crumple zones are
not quite so obvious. It's best seen in this picture:

http://ernest.isa-geek.org/Delta/Pictures/DykeDelta5.jpg

It's especially easy to see in Tom Bauer's red and white Delta on the
bottom. There is about 18" of steel and fiberglass that has to crumple
before outside objects can reach the the internal cage that forms the
cockpit. The cockpit frame has to bend up another foot or so before
reaching the pilot.

A zone of material that has to crumple before outside objects get to
you, ie, a crumple zone.

>
>>test than any other homebuilt design. Why would you need to do
>>destructive testing? Do I have to break my wings to prove they will
>>hold me up in flight?
>
>
> As far as I know, crumple zones are not reusable. Isn't that the point of
> them? How can you test the design if you don't do it destructively? Am I
> missing something here? Or are you saying that analysis is sufficient? Or
> are you confusing crumple zones with something else? I don't get your
> analogy, either. You test a wing structure by putting it under load and
> showing it holds; you test an energy dissipation feature like a crumple zone
> by subjecting it to an impact and showing that it crumples by the amount
> predicted.
>

Do you have to know the exact amount of energy the object will absorb
before deciding that you're safer with than without? I'm not saying
that this Delta can take on cliffs, I'm saying that in an off airport
landing, with all other things being equal (they never are though) the
Delta would be safER with it's crumple zone than the typical
conventional GA aircraft, and it cost nothing in additional weight,
labor or money. You don't have to spend millions as you claim to prove
the obvious.

>
>>the landing to an acute angle crumple zones WILL help.
>
>
> I didn't see the crumple zone features of the Delta that you are refering
> to.
>
>
>>Crashworthiness should be part of the primary structure. Not a heavy,
>>expensive afterthought.
>
>
> ALL of the crashworthiness considerations I've ever seen have been the usual
> "this is the max expected design load, so make it strong enough to withstand
> XX times that". Often, there is additional strength in components that
> protect the pilot. But that's different than crumple zones.
>

Maybe we should define what we're talking about. In my simplistic view,
a crumple zone is "stuff that breaks, so you don't have to". The front
leading edge is NOT designed to stop the Delta from flying through a
tree. It's designed to hold the nose in the air; HOWEVER, it is
completely willing to sacrifice itself to HELP the pilot survive that
close encounter with the wooden kind. A good design serves its purpose.
A great design will serve many purposes.

>
>>When I sit in my incomplete project, I can look around at all the steel
>
>
> Fine. If that gives you a warm fuzzy, then good for you. Me? I'll place my
> emphasis on accident prevention - both by design, training, and proper
> preparation.

Building this plane is taking me about 3yrs minimum. I don't see why
there's not time for all of it.

I take the viewpoint that **** is going to happen, no matter how much we
try to prevent it. If I assume that at some point I'll have to put down
when I really don't want to, I have the chance to prepare for it. Try
to prevent the bad stuff, but be ready in case it does finally happen.

>
>
>>There are not any electronics or flight systems that will ever make me
>
> feel safer than
>
>>several feet of protection between me and the hard stuff.
>
>
> Not even an angle-of-attack sensor? Dang. Given that they are available, I
> wouldn't consider building a new plane without one. But your Deltas don't
> have enough elevon authority to reach CLmax, so that's probably not an issue
> for you.
>
>
>

One of the other builders response to my question about AOA indicator
was that the best one for the Delta was the altimeter. If it's
unwinding too fast you need to let the nose down some 8*)

But to answer your question, if you're having to put it down in a small
field cause you blew a jug, how will the AOA indicator help with that
tree that's getting awfully close? When all your altitude and energy
has been spent and your low, slow and close to hard stuff, I'll take a
few pound of steel tube and fiberglass buffer over a ton of fancy
electronics any day.


--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[Pete Schaefer]

"Ernest Christley" > wrote in message
om...
> Does it have to be labeled "Crumple Zone" to work?

A crumple zone is a pretty specific type of structure. It's a technical
term.

> It's especially easy to see in Tom Bauer's red and white Delta on the
> bottom. There is about 18" of steel and fiberglass that has to crumple

That's unlikey to be a crumple zone. If you guys are just going to randomly
refer to anything outside the cockpit as a crumple zone, then there's no
basis for communication here.

> A zone of material that has to crumple before outside objects get to
> you, ie, a crumple zone.

Please don't make up definitions on your own for technical stuff. It just
confuses everyone.

> Do you have to know the exact amount of energy the object will absorb
> before deciding that you're safer with than without?

It's about quantifying a benefit. How much benefit -vs- how much weight,
etc. Do the math and make the design decision.

> landing, with all other things being equal (they never are though) the
> Delta would be safER with it's crumple zone than the typical
> conventional GA aircraft, and it cost nothing in additional weight,
> labor or money. You don't have to spend millions as you claim to prove
> the obvious.

Obvious? I call that speculation without a shred of evidence to support it.

> Maybe we should define what we're talking about. In my simplistic view,
> a crumple zone is "stuff that breaks, so you don't have to".

There is a ton of good technical info on crumple zones as used in automotive
design. Instead of pulling stuff out of your butt, go look it up.

> field cause you blew a jug, how will the AOA indicator help with that
> tree that's getting awfully close?

An AOA indicator will help you to precisely select a best-glide speed,
giving you more time and more options.

[George A. Graham]

On Fri, 14 May 2004, anonymous coward wrote:

a discussion of all
> the factors that affect safety in homebuilt aircraft.

My homebuilt airplane design has saved my bacon at least twice. It is
a canard pusher.

First, I landed very hard in high winds. I broke the nose gear linkage
and stopped quickly on the runway. A fellow canard builder flew in with
epoxy and cloth to patch the road rash, and another fellow mailed me some
brake calipers. A few weeks later, two men perished when they landed
hard in a tractor engine airplane. Their nose gear failed, the prop hit and
started a fire which they did not survive.

Second:
After one 1,000 mile long, very high flight (I have oxygen now), I turned
base to final too tightly, and the canard stalled. I leveled her off and builtup
speed, and did an extra trip around the pattern before landing.

I often read about stall/spin crashes, and am very glad to fly this bird.
It does prefer clean paved runways, it seems much more safe to me.

I learned to fly after I turned 50 years old, and do make newbie mistakes.


George Graham
RX-7 Powered Graham-EZ, N4449E
Homepage <http://bfn.org/~ca266>

[Ernest Christley]

Pete Schaefer wrote:
> "Ernest Christley" > wrote in message
> om...
>
>>Does it have to be labeled "Crumple Zone" to work?
>
>
> A crumple zone is a pretty specific type of structure. It's a technical
> term.
>

Technical terms have definitions, and believe it or not, I can read.
You can step off the high horse, 'cause we're all human here. If you've
got a definition that will change the definition from what I've stated,
then put it out there. You're liable to teach a whole lot of people a
thing or two, including myself. I've offered a simple, workable
definition below.

>
>>It's especially easy to see in Tom Bauer's red and white Delta on the
>>bottom. There is about 18" of steel and fiberglass that has to crumple
>
>
> That's unlikey to be a crumple zone. If you guys are just going to randomly
> refer to anything outside the cockpit as a crumple zone, then there's no
> basis for communication here.
>

Well, hell. I didn't mean for you to get your technical panties is a
wad. Anything outside the cockpit IS a crumple zone if

1) it gets between you and the hardstuff, and
2) it's not so strong that you break before it does

By this definition, if something extreme happens and you somehow come
down backwards, landing on your tail with the nose straight up, then the
whole aft fuselage becomes a crumple zone.

>
>>A zone of material that has to crumple before outside objects get to
>>you, ie, a crumple zone.
>
>
> Please don't make up definitions on your own for technical stuff. It just
> confuses everyone.
>

Whew!! The snots flying now!

Uh. Excuse me. This IS r.a.h. you know. Making up our own definitions
is what we do best.

>
>>Do you have to know the exact amount of energy the object will absorb
>>before deciding that you're safer with than without?
>
>
> It's about quantifying a benefit. How much benefit -vs- how much weight,
> etc. Do the math and make the design decision.
>

Uh. Excuse me again. There is NO weight added. You've just put part
of the structure that has to be there anyway between yourself and
obstacles. It's stuff that crumples, and it's in a zone (around here,
we call it "The Stuff to the Front and Side of Daddy Zone", careful I
have that phrase copyrighted, possibly trademark, and I'm gonna talk to
a lawyer about a patent), therefore it's a crumple zone.

>
>>landing, with all other things being equal (they never are though) the
>>Delta would be safER with it's crumple zone than the typical
>>conventional GA aircraft, and it cost nothing in additional weight,
>>labor or money. You don't have to spend millions as you claim to prove
>>the obvious.
>
>
> Obvious? I call that speculation without a shred of evidence to support it.

Nope no evidence whatsoever, and I'm not about to go out and bend up a
bunch of perfectly good, expensive and increasingly scarce 1" 4130 steel
tube to prove that it absorbs a lot of energy as it's bending.

>
>
>>Maybe we should define what we're talking about. In my simplistic view,
>>a crumple zone is "stuff that breaks, so you don't have to".
>
>
> There is a ton of good technical info on crumple zones as used in automotive
> design. Instead of pulling stuff out of your butt, go look it up.
>

Look at all the technical info you want. A zone that crumples. It's
self defining. I don't need a self styled expert to tell me that I'm
safer if I have something other than me to absorb the impact energy.

>
>>field cause you blew a jug, how will the AOA indicator help with that
>>tree that's getting awfully close?
>
>
> An AOA indicator will help you to precisely select a best-glide speed,
> giving you more time and more options.
>
>

OK, you've had a perfect glide into the only field in the valley as you
tried to cross the mountain. You're just below the treetops, and the
end of the field is coming quick. How many options will the indicator
give you?

Besides, that's what the airspeed indicator is for.

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[Pete Schaefer]

"Ernest Christley" > wrote in message
om...
> Technical terms have definitions, and believe it or not, I can read.

Well, then look it up. Rather than get offended, go look it up on Google.
You'll get tons of hits, but there will be some gems there that explain the
concept. It wasn't me that started applying the term "crumple zone" to
every part of the airplane.

> Well, hell. I didn't mean for you to get your technical panties is a
> wad. Anything outside the cockpit IS a crumple zone if
> 1) it gets between you and the hardstuff, and
> 2) it's not so strong that you break before it does

Your definition is way too general and does not match up with common usage
in the engineering circles where the term comes from.A crumple zone is a
structural piece that is designed to compress in a specific way under a load
in a certain direction. Instead of just tearing to pieces, it folds up like
an accordion, thus reducing the peak stresses transmitted to the rest of the
structure. A crumple zone is designed to collapse upon reaching a certain
threshold, usually determined by some maximum impact velocity and the weight
of the rest of the structure. Think about an empty soda can. If you
carefully stand on it, it might support your weight. If you hop up onto it,
the sides will fold up like an accordion. Put a can on it's side, and it
fails in quite a different manner.

> Uh. Excuse me. This IS r.a.h. you know. Making up our own definitions
> is what we do best.

Yup. It's one of my chief annoyances of newsgroups: very low signal to noise
ratio.

> Nope no evidence whatsoever, and I'm not about to go out and bend up a
> bunch of perfectly good, expensive and increasingly scarce 1" 4130 steel
> tube to prove that it absorbs a lot of energy as it's bending.

If I had an idea for, say, a new engine mount system that could dramatically
increase my chance of survival without increasing weight that much, I
wouldn't hesitate for a second to build a prototype and at least put it
through some static load tests. You wouldn't necessarily have to wreck an
entire airframe, as long as you could demonstrate the behavior with an
appropriate design load.

If you don't want to go through that, then do what everyone else does and
pick a max design load and apply an overdesign factor.

> Look at all the technical info you want. A zone that crumples. It's
> self defining. I don't need a self styled expert to tell me that I'm
> safer if I have something other than me to absorb the impact energy.

Fine, stick to your own definitions if you want. It's not my goal in life to
educate you. And I never claimed to be a structures expert, but I do
interface with guys every day who are. I understand the issues and how they
affect what I do. But I don't go around changing definitions.

> OK, you've had a perfect glide into the only field in the valley as you
> tried to cross the mountain. You're just below the treetops, and the
> end of the field is coming quick. How many options will the indicator
> give you?

If you've taken advantage of the best your airframe can do, then maybe
you've arrived above the valley with enough altitude so that you have a
choice as to what direction you're going to land in.

> Besides, that's what the airspeed indicator is for.

And how do you chose the best airspeed? Just pick one out of a book? Well,
the best airspeed changes based on your current loadout. The optimum angle
of attack for glide does not change. Without looking at alpha, you're just
going on a rough guess that will likely be off significantly.

> "Ignorance is mankinds normal state,
> alleviated by information and experience."

Anyway, I've done all the typing on this topic that I'm going to do. If you
want to deviate from the normal state some more, there's plenty of books,
articles, etc., out there for you to read. You don't have to take my word
for anything. Given that you've chosen a low aspect-ratio design, not having
any choices where you set your airplane down may be much more of a reality
for you.

[[email protected]]

On Fri, 21 May 2004 03:15:13 GMT, Ernest Christley
> wrote:

>> That's unlikey to be a crumple zone. If you guys are just going to randomly
>> refer to anything outside the cockpit as a crumple zone, then there's no
>> basis for communication here.
>>
>
>Well, hell. I didn't mean for you to get your technical panties is a
>wad. Anything outside the cockpit IS a crumple zone if
>
>1) it gets between you and the hardstuff, and
>2) it's not so strong that you break before it does
>
>By this definition, if something extreme happens and you somehow come
>down backwards, landing on your tail with the nose straight up, then the
>whole aft fuselage becomes a crumple zone.

Is this what you meant when you said that the P-51 was built with
crumple zones? If that's what you meant, then this is a revisionist
interpretation of how the P-51 was designed and why.

That the P-51 had a monocoque type fuselage and the engine assembly
bolted to it, was just the way fighters were built. It was a
production thing, a compromise between what the engineers really
wanted and what was possible to get the airplanes out the door as
inexpensively as possible and still be lightweight and strong. That
the fuselage was stong was a necessity for combat, withstanding high G
maneuvers and near supersonic speeds, it had nothing to do with crash
safety.

The P-47 Thunderbolt was also designed exactly the same way: monocoque
fuselage and the engine bolted to the firewall. Except that Republic
decided to make the airplane REALLY strong. One example, according to
one of it's more famous pilots, rolled itself up into a ball in Long
Island sound after pulling out of a dive. The pilot was sitting on
the shore somewhat dazed but alive after crawling out of the wreckage
when they found him. Did Republic set out to specifically design the
P-47 to protect the pilot in crashes? No, but it was so strong that
it was more crashworthy than virtually any other fighter in WWII. It
paid for this crashworthiness by being the heaviest single engine
fighter of the war. The phenominal weight made it's climb, for a long
time, it's least impressive feature.

Corky Scott

[jls]

"George A. Graham" > wrote in message
...
> On Fri, 14 May 2004, anonymous coward wrote:
>
> a discussion of all
> > the factors that affect safety in homebuilt aircraft.
>
> My homebuilt airplane design has saved my bacon at least twice. It is
> a canard pusher.
>
> First, I landed very hard in high winds. I broke the nose gear linkage
> and stopped quickly on the runway. A fellow canard builder flew in with
> epoxy and cloth to patch the road rash, and another fellow mailed me some
> brake calipers. A few weeks later, two men perished when they landed
> hard in a tractor engine airplane. Their nose gear failed, the prop hit
and
> started a fire which they did not survive.
>
> Second:
> After one 1,000 mile long, very high flight (I have oxygen now), I turned
> base to final too tightly, and the canard stalled. I leveled her off and
builtup
> speed, and did an extra trip around the pattern before landing.
>
> I often read about stall/spin crashes, and am very glad to fly this bird.
> It does prefer clean paved runways, it seems much more safe to me.
>
> I learned to fly after I turned 50 years old, and do make newbie mistakes.
>
>
> George Graham
> RX-7 Powered Graham-EZ, N4449E
> Homepage <http://bfn.org/~ca266>
>

I saw a Long-Eze land gear-up at Oshkosh. All the emergency vehicles sped
to the downed aircraft. Adrenaline pumped. Not to worry, though. The
nose had a little bumper underneath which was barely even scuffed.

[Jim Harper]

(Jim-Ed Browne) wrote in message >...
>
> Today, light planes-particularly the ones that crash with six people
> and get the manufacturer sued-are always flown with power-on
> approaches _so the obsolete museum piece forward of the firewall
> doesn't get shock cooled_. Then said museum piece quits.... This is an
> example of "organized stupidity". An effective speedbrake/spoiler
> system would have prevented, in my opinion and in that of many more
> well qualified people than myself, the majority of fatal Bonanza
> crashes in the last 40 years.

Mr. Jimed...I suspect that you are merely a troll, and to those on rah
who have been ignoring you, I apologize. On the other hand, this post
represents an abysmal lack of knowledge and requires comment.

Specifically, I would like to point out that your claim that power-on
approaches are "so (the tried and true aircraft engine) forward of the
firewall doesn't get shock cooled..." is patently absurd. Power-on
landings are used to control the descent rate of the airplane...or to
remove the far too effective drag device of the windmilling propeller
(as in my RV-8A)...or for other reasons, but certainly not to prevent
shock-cooling. The minimal application of the throttle needed would
not be accomplish that goal, firstly, and secondly, the time for that
is long past on landing approach.

I have little doubt that this represents a precis' of your entire
knowledge base regarding things aeronautical, and with that, am done
with you.

Jim
RV-8A N888FP

[anonymous coward]

>> guessing you would need quite soft foam, otherwise it wouldn't deform
>
> The foams they use for helmets are pretty hard. They won't deform until you
> hit a threshhold. You don't want something that will compress under normal
> loads.

Agreed.

I imagine you would want something that would deform around (for the sake
of argument) 10-20Gs. One's back probably has 10-20x the surface area of
one's foot, so my worry is that if you used a foam that was soft enough to
protect your back, it would be easy to put your foot or elbow through it.

>> Another idea was putting a big chunk of foam at the front of the aircraft
>> to slow the deacceleration if you hit something frontways. Say you have to
>
> We could be talking about a lot of energy. Might require a lot of foam.
>
>> airframe may break. Perhaps a cubic foot of harder, crushable foam in the
>> nosecone could reduce peak loads on the airframe and spread them more
>
> Where in the nose would you put it?

Behind the canard - in my dreams.

> I was thinking of maybe something behind
> the instrument panel, maybe attached to the firewall. Speaking of fire....I
> think I have an old bicycle helmet laying around. Maybe I'll put a match to
> it.

Good point.

> Anyway, I'm sure there's data available on foams currently in use.

I have heard that the racing drivers use alu honeycomb. That sounds like
it might be seriously expensive.

AC

[Pete Schaefer]

"anonymous coward" > wrote in message
. ..
> I imagine you would want something that would deform around (for the sake
> of argument) 10-20Gs.

Hmm....just shooting from the hip, that sounds like good range.

> one's foot, so my worry is that if you used a foam that was soft enough to
> protect your back, it would be easy to put your foot or elbow through it.

I'd think you'd put a covering of something rigid over it. Maybe a thin
layer of glass or maybe just some epoxy to make the top rigid enough to
prevent dinging it under normal use.

> Behind the canard - in my dreams.

Maybe the thing to do is mount the seat to something that will give somewhat
under crash loads. Might be hard in something like a Long/Vari-EZ, since (I
think, working from memory here) that the EZ seat is mounted directly to
some major structural members. Would need some additional stuff to isolate
the seat with some energy-absorbing stuff that would let it give a bit
(probably don't need more than a couple of inches in a crash).

> I have heard that the racing drivers use alu honeycomb. That sounds like
> it might be seriously expensive.

There's probably a ton of data on stuff that people have tried for driver
protection in the automotive world. Unfortunately, air-bags are out of the
question for aviation use (for the pilot at least....probably for everyone).
But there must be a ton of other stuff. I'd bet that NASA has sponsored a
bunch of research under the GA revitalization thingy that would be
applicable. Rather than us spend our time speculating here, maybe some
Google time is warranted. There is probably someone at NASA Langley that
would serve as a point of contact, too. There might even be some technology
transfer programs around that we could take advantage of. Not sure how they
would react to helping the average joe home-builder, but I'm sure they make
a lot of data available to certified manufacturers.

Pete

[Rich S.]

"Pete Schaefer" > wrote in message
news:xMprc.4694$ny.935185@attbi_s53...
>
> . . . Unfortunately, air-bags are out of the
> question for aviation use (for the pilot at least....probably for
everyone).

Not. See http://www.avweb.com/news/snf2003/184230-1.html - last article,
bottom of page.

Rich S.

[frank]

Air bags are a factory option on some certified planes, including the
Mooney. The bags are built into the seat belts.

Frank

"Rich S." > wrote in message
...
> "Pete Schaefer" > wrote in message
> news:xMprc.4694$ny.935185@attbi_s53...
> >
> > . . . Unfortunately, air-bags are out of the
> > question for aviation use (for the pilot at least....probably for
> everyone).
>
> Not. See http://www.avweb.com/news/snf2003/184230-1.html - last article,
> bottom of page.
>
> Rich S.
>
>

[Ernest Christley]

wrote:
> On Fri, 21 May 2004 03:15:13 GMT, Ernest Christley
> > wrote:
>
>
>>>That's unlikey to be a crumple zone. If you guys are just going to randomly
>>>refer to anything outside the cockpit as a crumple zone, then there's no
>>>basis for communication here.
>>>
>>
>>Well, hell. I didn't mean for you to get your technical panties is a
>>wad. Anything outside the cockpit IS a crumple zone if
>>
>>1) it gets between you and the hardstuff, and
>>2) it's not so strong that you break before it does
>>
>>By this definition, if something extreme happens and you somehow come
>>down backwards, landing on your tail with the nose straight up, then the
>>whole aft fuselage becomes a crumple zone.
>
>
> Is this what you meant when you said that the P-51 was built with
> crumple zones? If that's what you meant, then this is a revisionist
> interpretation of how the P-51 was designed and why.
>
> Corky Scott
>
>

That wasn't me claiming that, Corky, 'cause I know next to nothing about
the P51's construction or design.

It's just my contention that crash worthiness, called survivability in
the not to distant past, can be increased without a million dollar
budget and without a lot of extra weight. Common sense and load path
analysis are useful in this regime, and you don't have to wear white
coats and carry a slide rule to understand it. It is not hard to do,
produces useful results, and CAN NOT be replaced with electronics.

I would go more into the Delta's features, like how the forward cockpit
tapers back so that the longerons will bend away from the passengers in
the case of a frontal collision, but then I'd have to take more pictures
that show the structure clearly, and finish it up with dropping the
frame off a cliff to prove that the tail will in fact slow down as the
forward fuselage crumples. 8*)

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[Byron J. Covey]

The Grumman Ag Cat, among others, was designed with a stronger than required
(for mission or for certification) cockpit section/seat/roll-over
protection/restraint system. There are numerous examples of crashes that
pilots walked away from.


BJC



> wrote in message
...
> On 19 May 2004 12:03:24 -0700, (Jim-Ed Browne)
> wrote:
>
> > I recall that the P-51's designer, Dutch Kindelberger, designed the
> >cockpit area as the toughest structure, so everything else would
> >crumple around the pilot and provide protection from the sudden
> >impact. Is this somehow no longer feasible?
>
> You do? References please. I've studied that fighter for years and
> this is the first I've ever heard of Kindelberger designing the
> cockpit like a modern car is designed.
>
> Thanks, Corky Scott

[Kevin Horton]

On Fri, 21 May 2004 15:41:04 -0500, frank wrote:

> Air bags are a factory option on some certified planes, including the
> Mooney. The bags are built into the seat belts.
>
> Frank
>

How are these things controlled? Where is the g-switch that triggers
them? Do they need electrical power to run the system? I wonder what
sort of electrical failures could cause them to fire when they shouldn't?
There have been incidents and accidents where debris in wiring
bundles has shorted a live wire to another wire, thus sending voltage
where it wasn't meant to go. This could potentially cause one of those
air bags to fire when it shouldn't.

I wonder if the air bag would push forward on the yoke if it fired in
flight? If this happened at low altitude, or a high enough airspeed,
could it cause an accident? If so, could installing one of these
air bags actually reduce the level of safety? Of is the perception of
safety more important than actual safety?

Just wondering.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

[Vaughn]

"Kevin Horton" > wrote in message
...
> On Fri, 21 May 2004 15:41:04 -0500, frank wrote:
> I wonder if the air bag would push forward on the yoke if it fired in
> flight? If this happened at low altitude, or a high enough airspeed,
> could it cause an accident? If so, could installing one of these
> air bags actually reduce the level of safety? Of is the perception of
> safety more important than actual safety?

There are many "safety" devices, including airbags, safety belts, helmets
etc. that can occasionally backfire in a way to cause a death that might
otherwise not happen. The important thing is that after all is said and done,
the pile of people killed by the device must be much smaller than the pile of
people that would otherwise be dead without the device.


Vaughn

[Tim Ward]

"Pete Schaefer" > wrote in message
news:xMprc.4694$ny.935185@attbi_s53...
>
> "anonymous coward" > wrote in message
> . ..
> > I imagine you would want something that would deform around (for the
sake
> > of argument) 10-20Gs.
>
> Hmm....just shooting from the hip, that sounds like good range.
>
> > one's foot, so my worry is that if you used a foam that was soft enough
to
> > protect your back, it would be easy to put your foot or elbow through
it.
>
> I'd think you'd put a covering of something rigid over it. Maybe a thin
> layer of glass or maybe just some epoxy to make the top rigid enough to
> prevent dinging it under normal use.
>
> > Behind the canard - in my dreams.
>
> Maybe the thing to do is mount the seat to something that will give
somewhat
> under crash loads. Might be hard in something like a Long/Vari-EZ, since
(I
> think, working from memory here) that the EZ seat is mounted directly to
> some major structural members. Would need some additional stuff to
isolate
> the seat with some energy-absorbing stuff that would let it give a bit
> (probably don't need more than a couple of inches in a crash).
>
> > I have heard that the racing drivers use alu honeycomb. That sounds like
> > it might be seriously expensive.
>
> There's probably a ton of data on stuff that people have tried for driver
> protection in the automotive world. Unfortunately, air-bags are out of
the
> question for aviation use (for the pilot at least....probably for
everyone).
> But there must be a ton of other stuff. I'd bet that NASA has sponsored a
> bunch of research under the GA revitalization thingy that would be
> applicable. Rather than us spend our time speculating here, maybe some
> Google time is warranted. There is probably someone at NASA Langley that
> would serve as a point of contact, too. There might even be some
technology
> transfer programs around that we could take advantage of. Not sure how
they
> would react to helping the average joe home-builder, but I'm sure they
make
> a lot of data available to certified manufacturers.
>
> Pete

It would be interesting to build a seat supported by empty aluminum soda
cans. A two-high stack would give a fair amount of deceleration space.
Calibrate for the load by the number of cans you use in parallel.
My experience crunching them for recycling has been that, undented, they're
very consistent in how they crush.
A poor man's honeycomb?

Tim Ward

[Richard Riley]

On Fri, 21 May 2004 19:04:45 -0700, "Tim Ward" >
wrote:

:
:It would be interesting to build a seat supported by empty aluminum soda
:cans. A two-high stack would give a fair amount of deceleration space.
:Calibrate for the load by the number of cans you use in parallel.
:My experience crunching them for recycling has been that, undented, they're
:very consistent in how they crush.
:A poor man's honeycomb?

I know one of the missionary flying groups makes seat supports out of
columns of rolled up corrugated cardboard - great energy absorbtion.
Low density urethane foam works nicely too - crushes and doesn't
rebound.

When I was in high school in the 70's in physics class we made a 10
mph bumper for a car out of full soda cans - the energy went into the
soda spraying sideways. Very messy, but lots of fun.

[Richard Lamb]

Vaughn wrote:
>
> "Kevin Horton" > wrote in message
> ...
> > On Fri, 21 May 2004 15:41:04 -0500, frank wrote:
> > I wonder if the air bag would push forward on the yoke if it fired in
> > flight? If this happened at low altitude, or a high enough airspeed,
> > could it cause an accident? If so, could installing one of these
> > air bags actually reduce the level of safety? Of is the perception of
> > safety more important than actual safety?
>
> There are many "safety" devices, including airbags, safety belts, helmets
> etc. that can occasionally backfire in a way to cause a death that might
> otherwise not happen. The important thing is that after all is said and done,
> the pile of people killed by the device must be much smaller than the pile of
> people that would otherwise be dead without the device.
>
> Vaughn

Perhaps less obvious, but just as important is how HARD
that airbag hits you when it goes off.

The TV always shows it in slow motion - so you can see it happening.
In reality, that sucker is gonna slap you silly, if not completely out.

Richard

[Bernardo Melendez. Jr.]

Stealth Pilot > wrote in message >...
> On Sun, 16 May 2004 16:42:03 +0100, anonymous coward
> > wrote:
>
> >On Sat, 15 May 2004 15:14:41 +0000, Pete Schaefer wrote:
> >
> >> Landing speeds are a big driver for the amount of injury. I think that the
> >> FAA has a lot of data on this. Can't think of a reference off-hand, but you
>
> >
> >I like the look of the IBIS (http://www.junqua-aircraft.com/) and I'd
> >prefer to build in wood. But the more I read, the less good an idea the
> >Ibis seems (fast landing speeds - only a few complete, so perhaps more
> >prone to 'bugs' than established designs such as the LongEZ and friends).
>
> china plate (mate) if you want a very good economical wood design then
> the Corby Starlet has a lot to offer. it is aerobatic to 4g. has
> something like 33 years of safe proven use. its a design that has
> never had an AD issued for it. the owners I know just love them.
> very few have ever been pranged.
>
> recommended engine is a jabiru 2200cc. delivers about 11litres per
> hour fuel burn and can see the starlet to Vne in level flight.
>
> btw it is a real aeronautical engineer designed aeroplane.
> plans are about $aus200. 'bout $US150.
>
> do a web search for "Corby Starlet"
>
> Stealth Pilot

Hey, Stealth, I own N45BM, the first Corby Starlet to fly in the US.
Bernardo

[Corrie]

"Byron J. Covey" > wrote in message >...
> The Grumman Ag Cat, among others, was designed with a stronger than required
> (for mission or for certification) cockpit section/seat/roll-over
> protection/restraint system. There are numerous examples of crashes that
> pilots walked away from.

Ron Machado, in a safety seminar I went to years ago, explained how a
certificated light aircraft is designed so that if you can stop it in
as much as a tennis court, (18g decel) the cockpit will not collapse
and you can unstrap and walk away. Bruised from the belts, perhaps,
but otherwise unscathed.

[Stealth Pilot]

On 21 May 2004 22:24:27 -0700, (Bernardo Melendez.
Jr.) wrote:


>> >I like the look of the IBIS (http://www.junqua-aircraft.com/) and I'd
>> >prefer to build in wood. But the more I read, the less good an idea the
>> >Ibis seems (fast landing speeds - only a few complete, so perhaps more
>> >prone to 'bugs' than established designs such as the LongEZ and friends).
>>
>> china plate (mate) if you want a very good economical wood design then
>> the Corby Starlet has a lot to offer. it is aerobatic to 4g. has
>> something like 33 years of safe proven use. its a design that has
>> never had an AD issued for it. the owners I know just love them.
>> very few have ever been pranged.
>>
>> recommended engine is a jabiru 2200cc. delivers about 11litres per
>> hour fuel burn and can see the starlet to Vne in level flight.
>>
>> btw it is a real aeronautical engineer designed aeroplane.
>> plans are about $aus200. 'bout $US150.
>>
>> do a web search for "Corby Starlet"
>>
>> Stealth Pilot
>
>Hey, Stealth, I own N45BM, the first Corby Starlet to fly in the US.
>Bernardo

I tip my hat to you.
....and I notice that you havent felt the need to move on from it.
what do you think of them?

Stealth Pilot

[Byron J. Covey]

That's not exactly what it says:

Sec. 23.561

General.

(a) The airplane, although it may be damaged in emergency landing
conditions, must be designed as prescribed in this section to protect each
occupant under those conditions.
(b) The structure must be designed to [give each occupant every reasonable
chance of escaping serious injury when--]
(1) Proper use is made of seats, safety belts, and shoulder harnesses
provided for in the design;
(2) The occupant experiences the static inertia loads corresponding to the
following ultimate load factors--
(i) Upward, 3.0g for normal, utility, and commuter category airplanes, or
4.5g for acrobatic category airplanes;
(ii) Forward, 9.0g;
(iii) Sideward, 1.5g; and
(iv) Downward, 6.0g when certification to the emergency exit provisions of
Sec. 23.807(d)(4) is requested; and
(3) The items of mass within the cabin, that could injure an occupant,
experience the static inertia loads corresponding to the following ultimate
load factors--
(i) Upward, 3.0g;
(ii) Forward, 18.0g; and
(iii) Sideward, 4.5g.
(c) Each airplane with retractable landing gear must be designed to protect
each occupant in a landing--
(1) With the wheels retracted;
(2) With moderate descent velocity; and
(3) Assuming, in the absence of a more rational analysis--
(i) A downward ultimate inertia force of 3g; and
(ii) A coefficient of friction of 0.5 at the ground.
(d) If it is not established that a turnover is unlikely during an emergency
landing, the structure must be designed to protect the occupants in a
complete turnover as follows:
(1) The likelihood of a turnover may be shown by an analysis assuming the
following conditions--
(i) [The most adverse combination of weight and center of gravity position;
(ii) [Longitudinal load factor of 9.0g;
(iii) [Vertical load factor of 1.0g; and
(iv) [For airplanes with tricycle landing gear, the nose wheel strut failed
with the nose contacting the ground.]
(2) For determining the loads to be applied to the inverted airplane after a
turnover, an upward ultimate inertia load factor of 3.0g and a coefficient
of friction with the ground of 0.5 must be used.
[(e) Except as provided in Sec. 23.787(c), the supporting structure must be
designed to restrain, under loads up to those specified in paragraph (b)(3)
of this section, each item of mass that could injure an occupant if it came
loose in a minor crash landing.]


BJC


"Corrie" > wrote in message
om...
> "Byron J. Covey" > wrote in message
>...
> > The Grumman Ag Cat, among others, was designed with a stronger than
required
> > (for mission or for certification) cockpit section/seat/roll-over
> > protection/restraint system. There are numerous examples of crashes
that
> > pilots walked away from.
>
> Ron Machado, in a safety seminar I went to years ago, explained how a
> certificated light aircraft is designed so that if you can stop it in
> as much as a tennis court, (18g decel) the cockpit will not collapse
> and you can unstrap and walk away. Bruised from the belts, perhaps,
> but otherwise unscathed.

[Jerry Springer]

Corrie wrote:
> "Byron J. Covey" > wrote in message >...
>
>>The Grumman Ag Cat, among others, was designed with a stronger than required
>>(for mission or for certification) cockpit section/seat/roll-over
>>protection/restraint system. There are numerous examples of crashes that
>>pilots walked away from.
>
>
> Ron Machado, in a safety seminar I went to years ago, explained how a
> certificated light aircraft is designed so that if you can stop it in
> as much as a tennis court, (18g decel) the cockpit will not collapse
> and you can unstrap and walk away. Bruised from the belts, perhaps,
> but otherwise unscathed.


Does Rod have a brother named Ron?

[anonymous coward]

On Fri, 21 May 2004 16:04:45 +0000, Pete Schaefer wrote:

[snip]

> There's probably a ton of data on stuff that people have tried for
> driver protection in the automotive world. Unfortunately, air-bags are
> out of the question for aviation use (for the pilot at least....probably
> for everyone). But there must be a ton of other stuff. I'd bet that
> NASA has sponsored a bunch of research under the GA revitalization
> thingy that would be applicable. Rather than us spend our time
> speculating here, maybe some Google time is warranted.

I agree that sounds sensible. I have a horror of reinventing the wheel -
and with a biomedical background I don't immediately have the ability
either (when it comes to engineering). I've googled a bit, but not found
much. When I'm less busy in a few months, I may give it another go.

I did just found this website website though:

http://home.att.net/~m-sandlin/goat.htm

describing some glider designs by a guy who believes he has built some
useful structural protection into them.

AC

[Ed Wischmeyer]

> I did just found this website website though:
> describing some glider designs by a guy who believes he has built some
> useful structural protection into them.

There's a world of difference between a 22 MPH landing in an ultralight
glider and a landing at 3 times that speed in an airplane.

Homebuilding prominently includes accepting additional risks to gain
certain perceived advantages. If risk minimization is your goal,
homebuilding is very much the hard way to achieve it.

Ed Wischmeyer

[Roger Halstead]

On Sat, 29 May 2004 04:31:36 +0100, anonymous coward
> wrote:

>On Fri, 21 May 2004 16:04:45 +0000, Pete Schaefer wrote:
>
>[snip]
>
>> There's probably a ton of data on stuff that people have tried for
>> driver protection in the automotive world. Unfortunately, air-bags are
>> out of the question for aviation use (for the pilot at least....probably

There was a program on the discovery channel a while back covering
research on crash survivability being built into modern *plastic*
airplanes.

They covered collapsible seats and also talked about including
airbags. If it's an out and out crash, the pilot needs the protection
as well as any one else. Once the G-limit required to fire the airbags
he's considered through flying and along for the ride at that point.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

>> for everyone). But there must be a ton of other stuff. I'd bet that
>> NASA has sponsored a bunch of research under the GA revitalization
>> thingy that would be applicable. Rather than us spend our time
>> speculating here, maybe some Google time is warranted.
>
>I agree that sounds sensible. I have a horror of reinventing the wheel -
>and with a biomedical background I don't immediately have the ability
>either (when it comes to engineering). I've googled a bit, but not found
>much. When I'm less busy in a few months, I may give it another go.
>
>I did just found this website website though:
>
>http://home.att.net/~m-sandlin/goat.htm
>
>describing some glider designs by a guy who believes he has built some
>useful structural protection into them.
>
>AC

[Richard Lamb]

Ok, enough abstract thinking.
Let's see what you guys can dream up for a specific airframe.

This is a proposed single seat all metal low wing sportster.

Power is intended to be 2180 VW or Rotax 912.

Figure 550 empty weight, 900 gross?

I've got 33 pounds budgeted for payload.

How much of that do you guys thing should be spent on
crash protection?


http://home.earthlink.net/~n6228l/l-one.htm


Richard Lamb

[anonymous coward]

On Sun, 30 May 2004 18:44:20 +0000, Richard Lamb wrote:

> Ok, enough abstract thinking.
> Let's see what you guys can dream up for a specific airframe.

With your weight budget I guess it's useless to try to design a plane that
you can nosedive in at Vne and walk away from... Probably better to
concentrate on the low-hanging fruit (assuming there is some).

My guess is that the best place to look for this, would be in injuries
that are neither fatal nor insignificant - though I guess there may also
be fatalities that have been prevented just as easily.

I don't trust my intuitions on the subject - does anyone know of any
sources that say what the most common non-fatal injuries are in GA
accidents? My guess is that they'd need to be pretty specific - 'back
injury' would not be much help; 'lower back injury due to high descent
rate at landing' would be.

I'm happy to browse a database if someone can point me in the right
direction - I just don't know where to look.

> This is a proposed single seat all metal low wing sportster.
>
> Power is intended to be 2180 VW or Rotax 912.
>
> Figure 550 empty weight, 900 gross?
> I've got 33 pounds budgeted for payload.

The hang-glider pilot in me says that's enough for a camera, some
lunch and a flask with plenty to spare. The long-distance cyclist within
me says that's not even enough for a tent, lunch, a stove, a toolkit, a
coat and a bicycle pump.

> How much of that do you guys thing should be spent on
> crash protection?

I guess the question is, 'how much of that can we persuade you to spend on
crash protection?'

And is there anything else you'd rather put in than 'structural
protection'? - e.g. a ballistic 'chute (if you believe in them).

> http://home.earthlink.net/~n6228l/l-one.htm
>

The CAD drawings look sweet...

AC

[Ed Wischmeyer]

> With your weight budget I guess it's useless to try to design a plane
that
> you can nosedive in at Vne and walk away from... Probably better to
> concentrate on the low-hanging fruit (assuming there is some).

Go buy an old cropduster -- they're far and away the most crashworthy
aircraft out there

Ed Wischmeyer

[Ron Wanttaja]

On Mon, 31 May 2004 06:58:35 -0700, Ed Wischmeyer >
wrote:

>> With your weight budget I guess it's useless to try to design a plane
>that
>> you can nosedive in at Vne and walk away from... Probably better to
>> concentrate on the low-hanging fruit (assuming there is some).
>
>Go buy an old cropduster --

How much is BOb going for? :-)

Ron Wanttaja

[Richard Lamb]

Nose in at Vne, you are gonna get what you deserve!
Let's look at the things we CAN survive and try to improve our
poor sucker's chances.

I already have four compression fractured vertebra, so this is not
just an academic exercise. (From my fun summer vacation in Viet Nam)

Sitting on the main spar like that, there just isn't a lot of
'crumple space' between the warm pink bottom and the cold hard ground.

So any landing that wipes out the gear could be pretty serious.

BTW, that is one of the things we are looking at very carefully.
In the event of a gear failure, where will all the big pieces go,
and will they go thru anything soft and squishy on the way out(?).

Beyond pilot comfort, I think this is a good place for a layer of
Temperfoam (seat bottom). It's heavy stuff for its size, but
Temperfoam will absorb quite a bit of energy in an impact situation.
Anything that can slow down the energy transfer - even a few more
milliseconds - will reduce back injuries significantly.
It shouldn't take more than six pounds for the foam.

After that, the most serious threat is smacking the head on something
hard or pointy. This cockpit is close enough that a good shoulder
harness should be mandatory. But that brings up the age old question
of where to attach the harness so that it can actually take the impact
load without failing the attach structure.

I'm guessing 30 G's (eyeballs forward) for 50 milliseconds?

Next, I worry about fires. Been there, singed holes in my T shirt.
A big gas tank in front of the panel is the simplest lightest way
to store gas, but it is also vulnerable in an accident. Cracks in
the tank, broken out fittings, or fuel line torn loose? None of
these are pleasant options when the gas is sitting in your lap.

However, on this plane, there is no way to put 20 gallons (120 lbs)
in a nose tank and still be within the CG range. For that one reason
we have decided to put the tanks in the wings. Ok, so now, do we
still want to have a header tank at the firewall (for a gravity feed),
or feed directly from the wing tanks (gotta have fuel pumps anyway!)?

Lastly, reducing the amount of commanded energy at touch down is
probably the best way to improve survivability. Get the stall speed
down as much as practical.

My first wing estimates indicated stall speed about 65 mph.
(I had some rather impressive fantasies about cruise speed)
That's just way to very dam fast (for this old fart, any way).
Another 12 sq ft of area, and a slightly different airfoil
got it down to around 52 mph.

Only way to improve on that is to add flaps.
Flaps could cost as much as eight or ten pounds...
But getting the landing speed down to 45 MPH or so?
Hard call there. (compromise)

I'm afraid a ballistic parachute is way over weight budget.
It certainly won't help you get over the trees at the end of the
runway...



Richard Lamb


http://home.earthlink.net/~n6228l/l-one.htm

[Pete Schaefer]

How much does a parachute weigh?

"Richard Lamb" > wrote in message
...
> I've got 33 pounds budgeted for payload.

[John Ammeter]

On Thu, 03 Jun 2004 02:42:50 GMT, "Pete Schaefer"
> wrote:

>How much does a parachute weigh?
>
>"Richard Lamb" > wrote in message
...
>> I've got 33 pounds budgeted for payload.
>


Twice as much as one chute...

Sorry, but I had to do that...

John

[anonymous coward]

I shall look forward to seeing how it all turns out.

Good luck, & keep us posted.

AC


On Mon, 31 May 2004 18:31:59 +0000, Richard Lamb wrote:

> I already have four compression fractured vertebra, so this is not
> just an academic exercise. (From my fun summer vacation in Viet Nam)
>
> Sitting on the main spar like that, there just isn't a lot of
> 'crumple space' between the warm pink bottom and the cold hard ground.
>
> So any landing that wipes out the gear could be pretty serious.
>
> BTW, that is one of the things we are looking at very carefully.
> In the event of a gear failure, where will all the big pieces go,
> and will they go thru anything soft and squishy on the way out(?).
>
> Beyond pilot comfort, I think this is a good place for a layer of
> Temperfoam (seat bottom). It's heavy stuff for its size, but
> Temperfoam will absorb quite a bit of energy in an impact situation.
> Anything that can slow down the energy transfer - even a few more
> milliseconds - will reduce back injuries significantly.
> It shouldn't take more than six pounds for the foam.

I never heard of it before - but it looks just the ticket.

> After that, the most serious threat is smacking the head on something
> hard or pointy. This cockpit is close enough that a good shoulder
> harness should be mandatory. But that brings up the age old question
> of where to attach the harness so that it can actually take the impact
> load without failing the attach structure.
>
> I'm guessing 30 G's (eyeballs forward) for 50 milliseconds?
>
> Next, I worry about fires. Been there, singed holes in my T shirt.
> A big gas tank in front of the panel is the simplest lightest way
> to store gas, but it is also vulnerable in an accident. Cracks in
> the tank, broken out fittings, or fuel line torn loose? None of
> these are pleasant options when the gas is sitting in your lap.
>
> However, on this plane, there is no way to put 20 gallons (120 lbs)
> in a nose tank and still be within the CG range. For that one reason
> we have decided to put the tanks in the wings. Ok, so now, do we
> still want to have a header tank at the firewall (for a gravity feed),
> or feed directly from the wing tanks (gotta have fuel pumps anyway!)?
>
> Lastly, reducing the amount of commanded energy at touch down is
> probably the best way to improve survivability. Get the stall speed
> down as much as practical.
>
> My first wing estimates indicated stall speed about 65 mph.
> (I had some rather impressive fantasies about cruise speed)
> That's just way to very dam fast (for this old fart, any way).
> Another 12 sq ft of area, and a slightly different airfoil
> got it down to around 52 mph.
>
> Only way to improve on that is to add flaps.
> Flaps could cost as much as eight or ten pounds...
> But getting the landing speed down to 45 MPH or so?
> Hard call there. (compromise)
>
> I'm afraid a ballistic parachute is way over weight budget.
> It certainly won't help you get over the trees at the end of the
> runway...

I loooked up BRS systems - 34lb lol.

>
>
> Richard Lamb
>
>
> http://home.earthlink.net/~n6228l/l-one.htm