Pick your brains?

[[email protected]]

http://www.eaach1.org/Design/comm6v1-1R4.pdf

Subject at hand: Landing gear design.

Article in above link pretty much puts into words my understanding of
why tail draggers do what they do. I've been thinking about an
original design for cheap one man flying (OK, lots of borrowed stuff
put together in my own unique way) and one of the little problems I
keep coming up with is cross wind control. Around here if it won't
land in a 10 Knot (gusting 30) side wind it's a fair weather toy.

For structural and weigh reasons a conventional 2 up front gear would
work best, but as we all know it isn't the best choice for low time
modern pilots, or cross wind conditions. A simple solution is a
castering main gear similar to John Moody's as used on the Easy
Riser. The problem then becomes one of ground handling due to lack of
directional control with respect to the ground. Complexity rules out
a fixed tail and steering main gear.

2 solutions:

1) Angle the axis of the castoring main gear so that the weight of
the craft tends to align the casters with the axis of the plane, or
use a locking, maybe semi locking as used in the nose gear of the
BD-5, castoring main gear. One could then use a conventional steering
tail wheel.

2) Pure differential braking in combination with a negative king
pin inclination - no lock or de-tent on main gear.

I'm open to all ideas and references to other planes that have used
similar gear - there must be some somewhere?

I have not had the option of examining an Ercoupe gear so any links to
pics/parts manuals would be appreciated. The B-52 gear is not under
consideration.................... :-)
======================
Leon McAtee

[bildan]

On Jul 9, 10:50*am, "
> wrote:
> http://www.eaach1.org/Design/comm6v1-1R4.pdf
>
> Subject at hand: *Landing gear design.
>
> Article in above link pretty much puts into words my understanding of
> why tail draggers do what they do. *I've been thinking about an
> original design for cheap one man flying (OK, lots of borrowed stuff
> put together in my own unique way) and one of the little problems I
> keep coming up with is cross wind control. *Around here if it won't
> land in a 10 Knot (gusting 30) side wind it's a fair weather toy.
>
> For structural and weigh reasons a conventional 2 up front gear would
> work best, but as we all know it isn't the best choice for low time
> modern pilots, or cross wind conditions. *A simple solution is a
> castering main gear similar to John Moody's as used on the Easy
> Riser. *The problem then becomes one of ground handling due to lack of
> directional control with respect to the ground. *Complexity rules out
> a fixed tail and steering main gear.
>
> 2 solutions:
>
> 1) * * Angle the axis of the castoring main gear so that the weight of
> the craft tends to align the casters with the axis of the plane, or
> use a locking, maybe semi locking as used in the nose gear of the
> BD-5, castoring main gear. *One could then use a conventional steering
> tail wheel.
>
> 2) * * Pure differential braking in combination with a negative king
> pin inclination *- no lock or de-tent on main gear.
>
> I'm open to all ideas and references to other planes that have used
> similar gear - there must be some somewhere?
>
> I have not had the option of examining an Ercoupe gear so any links to
> pics/parts manuals would be appreciated. *The B-52 gear is not under
> consideration.................... *:-)
> ======================
> Leon McAtee

I recall flying a Cessna 170 with "crosswind gear" which was a sort of
castering main gear. It was the worst handling taildragger I have
ever flown. Almost all 170 owners modified their airplanes to non-
castering mains.

If you plan oleo type hydraulic struts for your mains, the alignment
"scissors" can be skewed so the wheels steer outboard (increase toe-
out) as the strut compresses. It sort of "steers into the skid" as
the airplane swerves and transfers weight onto the outer wheel. That
gives you an extra second or two to 'catch it" as a groundloop starts.

[cavelamb[_2_]]

Conventional gear design - no toe in - or out.
Build it as straight as you can.

Then learn to fly it...

[Scott[_7_]]

wrote:
> http://www.eaach1.org/Design/comm6v1-1R4.pdf
>
> Subject at hand: Landing gear design.
>

>
> For structural and weigh reasons a conventional 2 up front gear would
> work best, but as we all know it isn't the best choice for low time
> modern pilots, or cross wind conditions.

I vote for the pilot to become proficient in taildraggers. It really
isn't that hard. I may be biased a bit since I learned to fly in a
taildragger at age 15, so I really don't know anything else. All of the
taildraggers (and nosedraggers as well) I have flown in the subsequent
32 years have absolutely no more scratches on them than when I initally
climbed aboard...

Scott
Corben Junior Ace
(with time in the Cessna 140, Aeronca 11CC, Piper PA20, 8KCAB....)

[[email protected][_2_]]

On Jul 9, 11:40*pm, cavelamb > wrote:
> Conventional gear design - no toe in - or out.
> Build it as straight as you can.
>
> Then learn to fly it...

You kind of missed my objective. I learned in a PA-12 but I'm not
thinking just about myself. Many others can't or are unwilling to
learn. If you want new blood (pun not intended) in the sport you have
to cater the wants and - abilities - of the masses. Once we get them
some stick time then they can transition to something more
conventional,if they so desire.

Besides, think Ercoupe, Flea, Spratt. No cross control possible.
Imagine trying to land an otherwise stock Ercoupe converted to tail
wheel :-)


Editorial comment:
If we don't find a way to get the next generation in the air for fun
and recreation then the TSA/Homeland Security bunch will see to it
that Class A airspace is lowered to 1000' AGL.........."for your
protection" $50K LSAs won't do it!
=======================
Leon McAtee

[cavelamb[_2_]]

wrote:
> On Jul 9, 11:40 pm, cavelamb > wrote:
>> Conventional gear design - no toe in - or out.
>> Build it as straight as you can.
>>
>> Then learn to fly it...
>
> You kind of missed my objective. I learned in a PA-12 but I'm not
> thinking just about myself. Many others can't or are unwilling to
> learn. If you want new blood (pun not intended) in the sport you have
> to cater the wants and - abilities - of the masses. Once we get them
> some stick time then they can transition to something more
> conventional,if they so desire.
>
> Besides, think Ercoupe, Flea, Spratt. No cross control possible.
> Imagine trying to land an otherwise stock Ercoupe converted to tail
> wheel :-)
>
>
> Editorial comment:
> If we don't find a way to get the next generation in the air for fun
> and recreation then the TSA/Homeland Security bunch will see to it
> that Class A airspace is lowered to 1000' AGL.........."for your
> protection" $50K LSAs won't do it!
> =======================
> Leon McAtee

TSA is doing the best they can to close the skies already.
It looks like they have decided that's best for us.

As for the rest...

I've flown the Ercoupe - two and three control.
I much prefer the one with rudder pedals.
Even though they don't do very much.

But then my favorite bird the a 65 horse BC12D Taylorcraft.
If you can land that beast on the spot you can land anything.
It didn't take long to master.
And it cost $17k.

Nobody who works at it stays a newbie for long.

[Ray Adair]

wrote:
> On Jul 9, 11:40 pm, cavelamb > wrote:
>> Conventional gear design - no toe in - or out.
>> Build it as straight as you can.
>>
>> Then learn to fly it...
>
> You kind of missed my objective. I learned in a PA-12 but I'm not
> thinking just about myself. Many others can't or are unwilling to
> learn. If you want new blood (pun not intended) in the sport you have
> to cater the wants and - abilities - of the masses. Once we get them
> some stick time then they can transition to something more
> conventional,if they so desire.
>
> Besides, think Ercoupe, Flea, Spratt. No cross control possible.
> Imagine trying to land an otherwise stock Ercoupe converted to tail
> wheel :-)
>
>
> Editorial comment:
> If we don't find a way to get the next generation in the air for fun
> and recreation then the TSA/Homeland Security bunch will see to it
> that Class A airspace is lowered to 1000' AGL.........."for your
> protection" $50K LSAs won't do it!
> =======================
> Leon McAtee

Good point! We could learn from the amateur radio experience.

[[email protected][_2_]]

On Jul 10, 9:47*am, Ray Adair > wrote:

> Good point! We could learn from the amateur radio experience.

Good analogy! I'm one you lost from the amateur radio ranks. My
brain just doesn't work in the way needed to master code at a rate
fast enough to pass the old tests. As a result I left something I
found quite interesting. If there had been an alternate route to
getting involved maybe I would have kept at it. Who knows what I
might have learned in the last 40 years???

================
Leon McAtee

[Stealth Pilot[_2_]]

On Thu, 9 Jul 2009 09:50:37 -0700 (PDT), "
> wrote:

>http://www.eaach1.org/Design/comm6v1-1R4.pdf
>
>Subject at hand: Landing gear design.
>
>Article in above link pretty much puts into words my understanding of
>why tail draggers do what they do. I've been thinking about an
>original design for cheap one man flying (OK, lots of borrowed stuff
>put together in my own unique way) and one of the little problems I
>keep coming up with is cross wind control. Around here if it won't
>land in a 10 Knot (gusting 30) side wind it's a fair weather toy.
>
>For structural and weigh reasons a conventional 2 up front gear would
>work best, but as we all know it isn't the best choice for low time
>modern pilots, or cross wind conditions. A simple solution is a
>castering main gear similar to John Moody's as used on the Easy
>Riser. The problem then becomes one of ground handling due to lack of
>directional control with respect to the ground. Complexity rules out
>a fixed tail and steering main gear.
>
>2 solutions:
>
>1) Angle the axis of the castoring main gear so that the weight of
>the craft tends to align the casters with the axis of the plane, or
>use a locking, maybe semi locking as used in the nose gear of the
>BD-5, castoring main gear. One could then use a conventional steering
>tail wheel.
>
>2) Pure differential braking in combination with a negative king
>pin inclination - no lock or de-tent on main gear.
>
>I'm open to all ideas and references to other planes that have used
>similar gear - there must be some somewhere?
>
>I have not had the option of examining an Ercoupe gear so any links to
>pics/parts manuals would be appreciated. The B-52 gear is not under
>consideration.................... :-)
>======================
>Leon McAtee

I have a 25 year old W8 tailwind.
this can be landed in conditions with the windsock rigid across the
strip. this seems to be what you are attempting.

the key is the tailwheel which has a solid link from the rudder
bellcrank to the tailwheel control lug. any time you have the wheel (a
4" homebuilders solid wheel from aircraft spruce) on the ground you
can steer the tail into position. the bellcrank at the rudder is half
the distance out from centre that the tailwheel control lug is.
the other requirement is that the neutral position of the tailwheel
matches the neutral position of the rudder.

the toe in/toe out argument regarding the mains is resolved by
considering the dynamics occurring during a swing during landing.
if you are turning to the right then the aircraft inertia is thrown to
the outside of the turn which presses the left wheel harder onto the
pavement. if this wheel at that moment is pointing in the direction of
travel then it contributes no additional forces that you have to get
under control. for this reason the undercarriage leg should flex into
a toe out position. it is irrelevant what the static parked wheel
position is within reason.

understand Wittman's W8 undercarriage and you will have your solution.
Stealth Pilot