Have you guys ever noticed the void?

[Stealth Pilot]

I look at all the plans on offer for building aircraft and not one of
them ever includes any of the structural calculations.

Dont you guys ever feel totally unnerved by the fact that you have no
real idea of just where the strengths and weaknesses lie in a design?

If you cock up something during construction and you need to work out
whether it will be strong enough to carry the loads in spite of the
mistake how on earth do you make a sensible informed decision?

I never fail to be amazed that the absence of key information
verifying the structural integrity of a design is never seen as a
problem.
methinks it would make a really good EAA initiative for the second
century of aviation to start educating people to make available their
structural calcs.

Stealth(its a world wide void) Pilot

[[email protected]]

Stealth Pilot wrote:
>
> Dont you guys ever feel totally unnerved by the fact that you have no
> real idea of just where the strengths and weaknesses lie in a design?
>
------------------------------------------------------------------------------

So fill the void yourself. Slide rule, #2 yaller pencil and the back
of an envelop, you're half way there. (You may use a calculator, if
you wish.)

The other half has to do with the basic purpose of the 'Experimental -
Amateur Built' licensing category, in that it exists to foster
aeronautical education, which implies the need to know what you're
doing, if not from the outset, at least before first-flight.

And if that sounds slightly fey, as I'm sure it will to most of the
kit-assemblers, consider the other side of the coin: If the designer
provided you with detailed data, how would you know they were correct
without duplicating his calculations? Even then, weight -- that is,
ACTUAL weight -- is a critical factor in those calculations. A lot of
home-builts were designed by midgets for others of their kind and often
cite weights and g-factors that are wildly fallacious if not out-right
lies. Stuff a two hundred fifty pound lard-ass in the cockpit, use
real numbers and the calculations for some of the most popular designs
are liable to read 'Lawn Dart.'

Expecting the EAA to do something about your 'void' is wishful
thinking, in my opinion. Based on the advertisements and informercials
in their magazines, the EAA has no qualms about accepting money from
hucksters offering you everything from flying saucers to engines that
will rust out before they wear out.

I suggest the wiser course is to think for yourself If that requires
cracking a few books on airframe structural analysis, so be it. (Try a
search using 'fundamentals of aircraft structural analysis.' The books
are out there and fairly cheap, too -- apparently because nobody reads
them :-)

-R.S.Hoover

[Lou]

I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot. Most every calculation I need to make comes from an average, if
not a guess.

[[email protected]]

I don't see this as much of a problem. Most builders wouldn't know
what they were looking at anyway. Some of them can't even drill a
round hole in the right spot :-)

If the manufacturer has preformed static load tests, with
documentation, and the design has been in service for a while I
wouldn't have any worries. I wouldn't buy/build one that didn't have
documented load tests available, or many years of proven service.

If you cock up something during building replace it. If you have the
ability to properly calculate and test the repair/modification you
shouldn't need the original calculations.

As for the EAA initiative I would be in favor of some kind of a formal
independent plans rating system. The old NASAD was one such group. It
could keep lots of people from wasting money on plans for things like
the FX ultralight and jet powered rotor cycles.

I do have the designers calculations for my Duster, but if/when I do
modify it I'll do my own calcualtions from scratch.
======================
Just my opinion
Leon McAtee

[Richard Lamb]

I did some basic calculations on the wing used on the Chuckbird/Texas
Parasol
before building my first one. I came up with a shade over 4 G's at 650
pounds.
(seemed like a good idea before selling plans)

Then got Nuked by several guys who claimed the wing was "weak" - because
they
were building 650 pounds - EMPTY.(and it was my fault!?!)

E-bleepin'-nough!

Richard

Lou wrote:

> I have to admit he does bring up a good point. I have often wondered
> what the difference in strength's and weakness would be if I used
> different wood in my plane, or enlarged the components for a larger
> pilot. Most every calculation I need to make comes from an average, if
> not a guess.

[Ron Wanttaja]

On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:

> I have to admit he does bring up a good point. I have often wondered
> what the difference in strength's and weakness would be if I used
> different wood in my plane, or enlarged the components for a larger
> pilot.

Which is probably one reasons designers don't provide the equations. Many hate
it when folks make changes.

Ron Wanttaja

[John Ammeter]

Ron Wanttaja wrote:
> On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
>
>
>>I have to admit he does bring up a good point. I have often wondered
>>what the difference in strength's and weakness would be if I used
>>different wood in my plane, or enlarged the components for a larger
>>pilot.
>
>
> Which is probably one reasons designers don't provide the equations. Many hate
> it when folks make changes.
>
> Ron Wanttaja


especially when they then use the SAME name for the aircraft...

John

[Matt Whiting]

Ron Wanttaja wrote:
> On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
>
>
>>I have to admit he does bring up a good point. I have often wondered
>>what the difference in strength's and weakness would be if I used
>>different wood in my plane, or enlarged the components for a larger
>>pilot.
>
>
> Which is probably one reasons designers don't provide the equations. Many hate
> it when folks make changes.

Most equations for light airplane design are well established and have
been around for decades. What unique equations could a typical designer
provide?

Matt

[Richard Lamb]

Matt Whiting wrote:

> Ron Wanttaja wrote:
> > On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
> >
> >
> >>I have to admit he does bring up a good point. I have often wondered
> >>what the difference in strength's and weakness would be if I used
> >>different wood in my plane, or enlarged the components for a larger
> >>pilot.
> >
> >
> > Which is probably one reasons designers don't provide the equations. Many hate
> > it when folks make changes.
>
> Most equations for light airplane design are well established and have
> been around for decades. What unique equations could a typical designer
> provide?
>
> Matt

Bless you pilgrim, for you are wise beyond your years.

[Lou]

The designer may hate it when you change a few things, but as many
people have pointed out, every pilot is different. Some changes are a
need and some are for want. Is this any different then a person
customizing a harley to their liking and calling it a Harley? There are
many reasons to change somethings on a design, espessially in this
catagory.
Lou

[Ron Wanttaja]

On Tue, 10 Jan 2006 11:24:24 GMT, Matt Whiting > wrote:

> Ron Wanttaja wrote:
> >
> >>I have to admit he does bring up a good point. I have often wondered
> >>what the difference in strength's and weakness would be if I used
> >>different wood in my plane, or enlarged the components for a larger
> >>pilot.
> >
> >
> > Which is probably one reasons designers don't provide the equations. Many hate
> > it when folks make changes.
>
> Most equations for light airplane design are well established and have
> been around for decades. What unique equations could a typical designer
> provide?

Not the equations per se, but the precise values and the design margins of the
design in question, the non-designer's lack of understanding of the
interrelationships between design elements, and the legal implications of
*providing* the information.

Remember, the poster I responded to specifically referred to the substitution of
one material for another. It's sometimes more than a mere comparison of the
strengths of the materials.

Ron Wanttaja

[Ron Wanttaja]

On 10 Jan 2006 03:59:39 -0800, "Lou" > wrote:

> The designer may hate it when you change a few things, but as many
> people have pointed out, every pilot is different. Some changes are a
> need and some are for want. Is this any different then a person
> customizing a harley to their liking and calling it a Harley?

Not at all, it's exactly the same. Now, point out where Harley-Davidson
publishes the design data that one can use to make modifications.

Homebuilding *is* about experimentation, no question. I just feel that if
someone wants to make changes to an existing aircraft, they shouldn't be
offended if the original designer declines to help. If one owns the plans to
the aircraft, you have all the information you need to compute the effects of
your changes, using standard aircraft design books.

Ron Wanttaja

[Stealth Pilot]

On 9 Jan 2006 12:05:59 -0800, wrote:


>So fill the void yourself. Slide rule, #2 yaller pencil and the back
>of an envelop, you're half way there. (You may use a calculator, if
>you wish.)
>
I'm in the process of doing exactly that. ...and beyond that trying to
get a book written targetted to the amateur designer.

>The other half has to do with the basic purpose of the 'Experimental -
>Amateur Built' licensing category, in that it exists to foster
>aeronautical education, which implies the need to know what you're
>doing, if not from the outset, at least before first-flight.
>
the weakness in the argument is that there is no way for someone
learning to verify their calculations.
the absolute absence of calculations available for learning or
developing from means that while our building skills and confidence
may be in the second century of aviation our design skills are right
back there with the wright brothers.

>And if that sounds slightly fey, as I'm sure it will to most of the
>kit-assemblers, consider the other side of the coin: If the designer
>provided you with detailed data, how would you know they were correct
>without duplicating his calculations?

my point exactly. I want to verify the calculations. the aircraft I am
building is aerobatted by some and declared by others to have a 3.8g
ultimate wing. only access to the designers numbers will allow me to
sort the bs from the advertised claims and see what the actual
situation was when designed and now.

> Even then, weight -- that is,
>ACTUAL weight -- is a critical factor in those calculations. A lot of
>home-builts were designed by midgets for others of their kind and often
>cite weights and g-factors that are wildly fallacious if not out-right
>lies. Stuff a two hundred fifty pound lard-ass in the cockpit, use
>real numbers and the calculations for some of the most popular designs
>are liable to read 'Lawn Dart.'
>
again if the original calculations were available the folly would be
easy to establish by running the calculations with the actual weight
against the design strengths.

>Expecting the EAA to do something about your 'void' is wishful
>thinking, in my opinion.

the eaa dont design aircraft. this is something that the eaa cant do.
this is however something that each and every designer can assist in
easily. I think that this black void in the homebuilding area actually
covers up a lot of ignorance. while it is easy to pretend that you
understand, in very many cases I have found that fear of ridicule is
behind keeping what calculations have been made secret.
we need to modify our environment to make the publication of design
calcs a part of creating a design. that way we will develop more
competent design knowledge in the community.

come to think of it the eaa I'm sure would be more than happy to add a
section to the members area to hold sets of design calcs.
>
>I suggest the wiser course is to think for yourself If that requires
>cracking a few books on airframe structural analysis, so be it. (Try a
>search using 'fundamentals of aircraft structural analysis.' The books
>are out there and fairly cheap, too -- apparently because nobody reads
>them :-)
and all you get from that is a guessed set of figures which tell you
nothing about the oversights in design or the plain errors in
calculation that have crept through.
the design book that I was working through yesterday(Vogel) turns out
to have pages of stuffed up calculations in it. I learnt a lot from
working out that there must have been errors and correcting them but I
could have learnt far more with some valid example calcs to work
through.

if we are not to repeat all the mistakes and inefficiencies of the
last century of aviation, ie to progress to really efficient
homebuilts in the future, we really need to get the designs and the
calculations discussed not the bloody paint schemes.

think also on the consequences for safety. would all those guys have
died aerobatting in RV3's for instance if they had been able to see
the calcs for themselves? ...and to see how close they were pushing
it.
Stealth (working on it and I'm eaa712250 ) Pilot

[Stealth Pilot]

On Mon, 09 Jan 2006 22:13:59 GMT, Richard Lamb
> wrote:

>I did some basic calculations on the wing used on the Chuckbird/Texas
>Parasol
>before building my first one. I came up with a shade over 4 G's at 650
>pounds.
>(seemed like a good idea before selling plans)
>
>Then got Nuked by several guys who claimed the wing was "weak" - because
>they
>were building 650 pounds - EMPTY.(and it was my fault!?!)
>
>E-bleepin'-nough!
>
>Richard

wings should have a 1.5 margin of safety so if your wing is 4g's at
650 lbs ultimate strength then you actually designed a 2.6g working
strength wing at that weight.
2.6 x 1.5 = 4

you make my point exactly. by publishing your figures others who are
interested can check your numbers and point out errors that you might
have missed.
60 degree banked turns would be ok but steepen up the bank angle a
little, hit some turbulence, .... poof, tinsel time.

got a sweat up? :-)


look at the rest of usenet. if you made an honest effort and stuffed
up someone would almost certainly post details of a more suitable
design.

I think that this is an area that we enthusiasts should be devoting
some attention to in the future.
Stealth Pilot

[Stealth Pilot]

On Mon, 09 Jan 2006 18:43:22 -0800, Ron Wanttaja
> wrote:

>On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
>
>> I have to admit he does bring up a good point. I have often wondered
>> what the difference in strength's and weakness would be if I used
>> different wood in my plane, or enlarged the components for a larger
>> pilot.
>
>Which is probably one reasons designers don't provide the equations. Many hate
>it when folks make changes.
>
>Ron Wanttaja

your honour I sold the guy the plans, I provided him with the worked
design calculations showing how the design was arrived at. the
comments in the calculations show how the material sizes were arrived
at. he has made changes to the aircraft which are neither in the
original designs nor show any validating calculations so my conclusion
is that he just guessed at the changes and proceeded blindly.
I cannot see how I can be held responsible for the stupidly
incompetent actions of others.

sounds like a defense to me.

Stealth Pilot

[Richard Lamb]

No sweat, just a basic misunderstanding.

We design to a 4 G _yiield_ limit.

This is where the wing, after being stressed, no longer
returns to the original shape
It has reached the "plastic" limit and has deformed.
Yes, it has failed, but it did not break.

The 1.5 G safety factor then gives a 6 G _ultimate_ limit.
THIS is where the wing breaks.

mo better?

Richard

[Richard Lamb]

Stealth Pilot wrote:

>
> your honour I sold the guy the plans, I provided him with the worked
> design calculations showing how the design was arrived at. the
> comments in the calculations show how the material sizes were arrived
> at. he has made changes to the aircraft which are neither in the
> original designs nor show any validating calculations so my conclusion
> is that he just guessed at the changes and proceeded blindly.
> I cannot see how I can be held responsible for the stupidly
> incompetent actions of others.
>
> sounds like a defense to me.
>
> Stealth Pilot

Don't get me wrong, Stealth, I hear what you are saying.

But I think the kind of analysis you imply is beyond anybody
but Boeing (even Airbus seems to have problems getting it right).


Igor Sikorsky was quoted as saying:

There are good designers with good designs and
good designers with bad designs,

And there are bad designers with good designs
and bad designers with bad designs.

If all designers flew their own designs, there would
eventually be only good designers with good designs.


A little old Russian arrogance, but an interesting point.

[Stealth Pilot]

On Wed, 11 Jan 2006 14:23:18 GMT, Richard Lamb
> wrote:

>No sweat, just a basic misunderstanding.
>
>We design to a 4 G _yiield_ limit.
>
>This is where the wing, after being stressed, no longer
>returns to the original shape
>It has reached the "plastic" limit and has deformed.
>Yes, it has failed, but it did not break.
>
>The 1.5 G safety factor then gives a 6 G _ultimate_ limit.
>THIS is where the wing breaks.
>
>mo better?
>
>Richard
>
>
your brow not mine :-)

muchos mo betta.

Stealth Pilot

[Stealth Pilot]

On Wed, 11 Jan 2006 14:38:02 GMT, Richard Lamb
> wrote:

>
>
>Stealth Pilot wrote:
>
>>
>> your honour I sold the guy the plans, I provided him with the worked
>> design calculations showing how the design was arrived at. the
>> comments in the calculations show how the material sizes were arrived
>> at. he has made changes to the aircraft which are neither in the
>> original designs nor show any validating calculations so my conclusion
>> is that he just guessed at the changes and proceeded blindly.
>> I cannot see how I can be held responsible for the stupidly
>> incompetent actions of others.
>>
>> sounds like a defense to me.
>>
>> Stealth Pilot
>
>Don't get me wrong, Stealth, I hear what you are saying.
>
>But I think the kind of analysis you imply is beyond anybody
>but Boeing (even Airbus seems to have problems getting it right).
>
>

no! simple aeroplanes like we're involved in dont have that
complicated a set of calcs. Evans did his for the vp1 in 25 pages.


>Igor Sikorsky was quoted as saying:
>
>There are good designers with good designs and
>good designers with bad designs,
>
>And there are bad designers with good designs
>and bad designers with bad designs.
>
>If all designers flew their own designs, there would
>eventually be only good designers with good designs.
>
>
>A little old Russian arrogance, but an interesting point.
>
he's absolutely right.

methinks itteration and access to other designs is what improves the
ante
Stealth Pilot

[Ron Wanttaja]

On Wed, 11 Jan 2006 22:08:05 +0800, Stealth Pilot > wrote:

> On Mon, 09 Jan 2006 18:43:22 -0800, Ron Wanttaja
> > wrote:
>
> >On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
> >
> >> I have to admit he does bring up a good point. I have often wondered
> >> what the difference in strength's and weakness would be if I used
> >> different wood in my plane, or enlarged the components for a larger
> >> pilot.
> >
> >Which is probably one reasons designers don't provide the equations. Many hate
> >it when folks make changes.
>
> your honour I sold the guy the plans, I provided him with the worked
> design calculations showing how the design was arrived at. the
> comments in the calculations show how the material sizes were arrived
> at. he has made changes to the aircraft which are neither in the
> original designs nor show any validating calculations so my conclusion
> is that he just guessed at the changes and proceeded blindly.
> I cannot see how I can be held responsible for the stupidly
> incompetent actions of others.
>
> sounds like a defense to me.

And by the time you get to tell your side of the story to the judge, you're out
$20,000 or so in attorney's fees. Burt Rutan never lost a lawsuit...but he got
tired of defending himself and got out of the homebuilt business twenty years
ago. One homebuilt company in the '80s was destroyed defending itself against a
suit where the customer drilled into his engine case to install a gauge but
didn't bother to remove the metal chips. They won the case...but went bankrupt
doing so.

Ron Wanttaja

[Lou]

With everything I have read in this posting, it leads me to one
question
Has anyone ever asked for the calculation?
After all not posting is not the same as refusing the request.
Lou

[Al]

"Ron Wanttaja" > wrote in message

>> >
>> >Which is probably one reasons designers don't provide the equations.
>> >Many hate
>> >it when folks make changes.
>>

And if the modified A/c has the same name as the original, the
designer and/or company can lose in the "court of public opinion", without
ever getting the truth out.

Al

[[email protected]]

Stealth Pilot wrote:
>(veeduber wrote:)
> >And if that sounds slightly fey, as I'm sure it will to most of the
> >kit-assemblers, consider the other side of the coin: If the designer
> >provided you with detailed data, how would you know they were correct
> >without duplicating his calculations?
>
> my point exactly. I want to verify the calculations.
--------------------------------------------------------------------------------------

Then flip that puppy over and start stacking on the cement sacks.

--------------------------------------------------------------------------------------

> the aircraft I am
> building is aerobatted by some and declared by others to have a 3.8g
> ultimate wing. only access to the designers numbers will allow me to
> sort the bs from the advertised claims and see what the actual
> situation was when designed and now.

--------------------------------------------------------------------------------------

Well... I hate to tell you this but the numbers alone won't give you
the Ultimate Answer. Load it to the max, turn it inside out whilst
upside down and you're liable to fail some itsy-bitsy part that was
never included in the calculations... but causes the wing to fall off
anyway.

--------------------------------------------------------------------------------------

> Stealth (working on it and I'm eaa712250 ) Pilot

--------------------------------------------------------------------------------

-R.S.Hoover
-EAA 58400
-(Been there; did that. Got the T-shirt)

[Highflyer]

"Stealth Pilot" > wrote in message
...
> On Mon, 09 Jan 2006 18:43:22 -0800, Ron Wanttaja
> > wrote:
>
>>On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
>>
>>> I have to admit he does bring up a good point. I have often wondered
>>> what the difference in strength's and weakness would be if I used
>>> different wood in my plane, or enlarged the components for a larger
>>> pilot.
>>
>>Which is probably one reasons designers don't provide the equations. Many
>>hate
>>it when folks make changes.
>>
>>Ron Wanttaja
>
> your honour I sold the guy the plans, I provided him with the worked
> design calculations showing how the design was arrived at. the
> comments in the calculations show how the material sizes were arrived
> at. he has made changes to the aircraft which are neither in the
> original designs nor show any validating calculations so my conclusion
> is that he just guessed at the changes and proceeded blindly.
> I cannot see how I can be held responsible for the stupidly
> incompetent actions of others.
>
> sounds like a defense to me.
>
> Stealth Pilot

Sorry. In our courts you are not held responsible for the stupidly
incompetent actions of others. However, if their stupid incompetent act
hurts someone and you have lots of money or they THINK you have lots of
money you ARE held responsible. For example, a fellow flew his Beech
Debonair into a mountain. When he hit the mountain a fuel line broke and
the wreck caught fire. Continental lost the suit for something like 100
million in punitive damages for building engines with fuel lines that can
break when you fly into a mountain. Incidently the lawyer who did the song
and dance for the jury to win that award was almost incinerated himself when
he crashed the jet he bought with his proceeds on takeoff and it caught
fire.

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )

[Jim Carriere]

Highflyer wrote:
> "Stealth Pilot" > wrote in message
> ...
>> On Mon, 09 Jan 2006 18:43:22 -0800, Ron Wanttaja
>> > wrote:
>>
>>> On 9 Jan 2006 12:16:29 -0800, "Lou" > wrote:
>>>
>>>> I have to admit he does bring up a good point. I have often wondered
>>>> what the difference in strength's and weakness would be if I used
>>>> different wood in my plane, or enlarged the components for a larger
>>>> pilot.
>>> Which is probably one reasons designers don't provide the equations. Many
>>> hate
>>> it when folks make changes.
>>>
>>> Ron Wanttaja
>> your honour I sold the guy the plans, I provided him with the worked
>> design calculations showing how the design was arrived at. the
>> comments in the calculations show how the material sizes were arrived
>> at. he has made changes to the aircraft which are neither in the
>> original designs nor show any validating calculations so my conclusion
>> is that he just guessed at the changes and proceeded blindly.
>> I cannot see how I can be held responsible for the stupidly
>> incompetent actions of others.
>>
>> sounds like a defense to me.
>>
>> Stealth Pilot
>
> Sorry. In our courts you are not held responsible for the stupidly
> incompetent actions of others. However, if their stupid incompetent act
> hurts someone and you have lots of money or they THINK you have lots of
> money you ARE held responsible. For example, a fellow flew his Beech
> Debonair into a mountain. When he hit the mountain a fuel line broke and
> the wreck caught fire. Continental lost the suit for something like 100
> million in punitive damages for building engines with fuel lines that can
> break when you fly into a mountain. Incidently the lawyer who did the song
> and dance for the jury to win that award was almost incinerated himself when
> he crashed the jet he bought with his proceeds on takeoff and it caught
> fire.

What a waste of a good jet!

[Highflyer]

> wrote in message
oups.com...
>
> Stealth Pilot wrote:
>>(veeduber wrote:)
>> >And if that sounds slightly fey, as I'm sure it will to most of the
>> >kit-assemblers, consider the other side of the coin: If the designer
>> >provided you with detailed data, how would you know they were correct
>> >without duplicating his calculations?
>>
>> my point exactly. I want to verify the calculations.
> --------------------------------------------------------------------------------------
>
> Then flip that puppy over and start stacking on the cement sacks.
>
> --------------------------------------------------------------------------------------
>
>> the aircraft I am
>> building is aerobatted by some and declared by others to have a 3.8g
>> ultimate wing. only access to the designers numbers will allow me to
>> sort the bs from the advertised claims and see what the actual
>> situation was when designed and now.
>
> --------------------------------------------------------------------------------------
>
> Well... I hate to tell you this but the numbers alone won't give you
> the Ultimate Answer. Load it to the max, turn it inside out whilst
> upside down and you're liable to fail some itsy-bitsy part that was
> never included in the calculations... but causes the wing to fall off
> anyway.
>
> --------------------------------------------------------------------------------------
>
>> Stealth (working on it and I'm eaa712250 ) Pilot
>
> --------------------------------------------------------------------------------
>
> -R.S.Hoover
> -EAA 58400
> -(Been there; did that. Got the T-shirt)

For example, How many negative G's will your battery box take before it
releases the battery to depart the airplane in whatever manner it may
choose?

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )

Hey, start planning now --- 10th annual Pinckneyville rec.aviation flyin is
coming up May 19, 20, and 21. The motel is filling up fast! :-)


>

[Morgans]

"Highflyer" > wrote

> For example, How many negative G's will your battery box take before it
> releases the battery to depart the airplane in whatever manner it may
> choose?

Is there a story in that, HF? Have you bee doing some secret battery box
testing, without telling us about it?

Remember, confession is good for the soul! ;-)
--
Jim in NC

[Stealth Pilot]

On Thu, 12 Jan 2006 23:19:51 -0600, "Highflyer" > wrote:


>
>Sorry. In our courts you are not held responsible for the stupidly
>incompetent actions of others. However, if their stupid incompetent act
>hurts someone and you have lots of money or they THINK you have lots of
>money you ARE held responsible. For example, a fellow flew his Beech
>Debonair into a mountain. When he hit the mountain a fuel line broke and
>the wreck caught fire. Continental lost the suit for something like 100
>million in punitive damages for building engines with fuel lines that can
>break when you fly into a mountain. Incidently the lawyer who did the song
>and dance for the jury to win that award was almost incinerated himself when
>he crashed the jet he bought with his proceeds on takeoff and it caught
>fire.
>
>Highflyer
>Highflight Aviation Services
>Pinckneyville Airport ( PJY )
>

HF that is the closest to a proof that there is a god I have ever
seen.
you nearly had me turn religious ...but not quite :-)
Stealth Pilot

[John Ousterhout]

Highflyer wrote:

> Hey, start planning now --- 10th annual Pinckneyville rec.aviation flyin is
> coming up May 19, 20, and 21. The motel is filling up fast! :-)
>
> Highflyer
> Highflight Aviation Services
> Pinckneyville Airport ( PJY )

WOW, has it really been ten years? Why it seems like I've personally
known some of you clowns damn near forever.

- John Ousterhout -

Unofficial Pinckneyville Fly-In
http://www.ousterhout.net/pjy-faq.html

[Richard Lamb]

Having deliberated on this for a while, I'd like to try again.


For a 4 G wing (yield limit), if you pull over 4 G's, the structure
has_been_damaged - whether it came apart or not.
That's a period.


The 1.5 G safety factor _should_ give a 6 G tolerant structure, but
as has been discussed elsewhere, that should should be considered a
"should" when working on the back of an envelope.
Our limit is 4.


Operating at a higher weight, one would reduce the G limit allowed to
stay within the design envelope.


And conversely, operating at a lighter weight, one might allow a higher
G reading on the meter without exceeding the design limits.


It's all about Limits...


Which brings us to FAR Part 23 Load Factors.
Normal, utility and aerobatics categories.

Category Limit(n)Ult(n) Composite

Normal 3.8 5.7 7.6
Utility 4.4 6.6 8.8
Acrobatic 6.0 9.0 12


Normal category is limited to "non-aerobatic" flight
with no more than 60 degree banks.

Recall that a 60 degree banked coordinated turn will impose
a 2 G load on the plane (of the 3.8 G Limit)

Utility Category allows limited aerobatics, stalls, spins, etc.
and banks greater than 60 degrees.

Aerobatic category eliminates the above restrictions.


Evans(1) makes the point that "the Utility category is a good choice
for home builders because if the project turns out overweight
(more common than not) one can fall back on the normal category".


Because if weight didn't matter, neither would strength.


We'd just build them so strong they couldn't possible break
under any conditions - regardless of what is weighed...


Pop quiz:

1) An airliner at full gross is operating in what category?

2) Why the higher limits imposed on composite structures?


Richard

(1) Lightplane Designer's Handbook - Wm. S. Evans


In an infinite universe all things are possible,
unfortunately not all things are equally probable.

[Tim Ward]

"Richard Riley" > wrote in message
...
<snip>
> As always, RSH is right. The proof is in the pudding. Or in the
> putting in this case, of a large number of bags full of lead weights.
>
> The calculations for a composite wing are possible, but orders of
> magnitude more complex than an aluminum one. And the final product is
> so sensitive to building technique that the calcs are just a place to
> start for ordering your lead weights.
>
> The plane I'm working on right now is a single surface sail wing.
> (Coincidentally, for those of you who work for Ma Boeing - know who
> got the patent on the sail wing? Phill Condit.)
>
> Some of the loads - like those on the lift strut - are
> straightforward. But the horizontal bending on the front and aft spar
> are infinitely beyond me. And the structures guy I dug up at work
> said it would take him months. The way to test it? Put it on a truck
> and run it down the road till you hit 4 G's.
>
> I think the number of builders that would do something smart with
> those calcs is smaller than the number of builders that would do
> something dumb. And both groups combined are vastly smaller than the
> rest, who wouldn't do anything with them.
>
> If you want to know how strong *your* airplane is, with all your
> (inevitable) building imperfections. proof load it.

So, are you gonna build the truck, or contract with one of the hang glider
manufacturers that already have the instrumentation? (and the Nitrous
injection to get everything up to 80 mph).

Tim Ward

[J.Kahn]

Richard Lamb wrote:

>
>
> Pop quiz:
>
> 1) An airliner at full gross is operating in what category?
>
Normal

> 2) Why the higher limits imposed on composite structures?
>

Because of more variability in the strength characteristics of a
composite structure vs alum, structural scatter factor is higher
therefore more fudge factor must be included in design allowances.

John

Montreal

[J.Kahn]

My battery will have its own little parachute so my heirs can recover it
and add it to my estate. Problem solved! lol

John
>
>
> For example, How many negative G's will your battery box take before it
> releases the battery to depart the airplane in whatever manner it may
> choose?
>
> Highflyer
> Highflight Aviation Services
> Pinckneyville Airport ( PJY )
>
> Hey, start planning now --- 10th annual Pinckneyville rec.aviation flyin is
> coming up May 19, 20, and 21. The motel is filling up fast! :-)
>
>
>
>
>