Today's Message Index:
----------------------
1. 12:55 PM - Stabilizer incidence (LAWRENCE WILLIAMS)
2. 03:49 PM - Re: Stabilizer incidence ()
3. 05:53 PM - Tailwheel placement (Rick Holland)
4. 09:50 PM - Re: Tailwheel placement (Galen Hutcheson)
5. 10:30 PM - Re: Stabilizer incidence (Rcaprd@aol.com)
Message 1
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| Subject: | Stabilizer incidence |
I just got back and have been wading through several days worth of posts. Interesting
to note the comments about the stab incidence and various "fixes" as well
as the standard aerodynamics 101 explanations.
I noticed as a kid that some old, slow free-flight models, especially the ones
with undercambered airfoils had LIFTING stabs. Sort of goes against what we claim
to be gospel in today's world. The reasoning was that with CG could be moved
further aft and not be burdened by stalls, snap-rolls and possible resulting
spins. So, how might this apply to our Piets? They are slow and have an ubdercambered
wing also.
Take a look at inflight photos of Piets and notice that many of them have a drooping
elevator! I know mine does and I have seen some others in the Brodhead pattern
that do also.
One other extreme example is the Bleriot Monoplane that has an undercambered stab.
Let's not be too hasty in having new builders camber their stabs either on top
or on the bottom. Remember all this website does is exchange ideas and, even though
they might sound logical, it's not the poster that has his butt on the line
when it's time to go.......
Larry
Message 2
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| Subject: | Re: Stabilizer incidence |
Welcome back, Larry.
The suggestion is not to build in any stabilizer incidence. Just build in a
way to adjust the incidence later if needed. Simple to do by adding shims above
and below
the stabilizer. You would then be free to rearrange the shims without
affecting the fin location. If the fin remains in the same location then the
rudder hinges won't be affected.
Greg Cardinal
----- Original Message -----
From: LAWRENCE WILLIAMS
To: Pietenpol-List Digest Server
Sent: Sunday, June 05, 2005 2:54 PM
Subject: Pietenpol-List: Stabilizer incidence
I just got back and have been wading through several days worth of posts. Interesting
to note the comments about the stab incidence and various "fixes" as
well as the standard aerodynamics 101 explanations.
I noticed as a kid that some old, slow free-flight models, especially the ones
with undercambered airfoils had LIFTING stabs. Sort of goes against what we
claim to be gospel in today's world. The reasoning was that with CG could be
moved further aft and not be burdened by stalls, snap-rolls and possible resulting
spins. So, how might this apply to our Piets? They are slow and have an ubdercambered
wing also.
Take a look at inflight photos of Piets and notice that many of them have a drooping
elevator! I know mine does and I have seen some others in the Brodhead
pattern that do also.
One other extreme example is the Bleriot Monoplane that has an undercambered
stab.
Let's not be too hasty in having new builders camber their stabs either on top
or on the bottom. Remember all this website does is exchange ideas and, even
though they might sound logical, it's not the poster that has his butt on the
line when it's time to go.......
Larry
Message 3
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| Subject: | Tailwheel placement |
Hey guys, I am using a two leaf leaf spring and a Matco tailwheel and was
wondering where the best position for the tailwheel was. The plans-built
tailwheel show the wheel center maybe three or four inches forward of the
back end of the fuselage. With the leaf spring setup the wheel center will
end up around 12" behind the rear end of the fuselage. Naturally this is a
negative as far as adding to tail heavyness but doesn't a longer wheelbase
(distance from main gear to tailwheel) improve ground handling stability?
Most factory taildraggers are setup this way for some reason (Cubs, 140s,
180s, etc).
Thanks
--
Rick Holland
Ribs, tailfeathers, center section done, fuselage ready for gear now.
Message 4
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s=s1024; d=yahoo.com;
b=zxLGpbZNa2sWOmx0+4qSirduO4kdB/rVOcnRKl/fbJaQY91DqJJ5w0Hui4INI9DumNO+cQbzmk1yVutD9sP7MXGZyeLwYVfDxAEVkZU7x19nVn0Pg3kY4z6aRXLSf2LO7iPV0f5CLcUe3jpA3MBmUKh9C3+g1c7lolqReS9Av5k=
;
| Subject: | Re: Tailwheel placement |
--> Pietenpol-List message posted by: Galen Hutcheson <wacopitts@yahoo.com>
Rick, short wheel-based tail-draggers are more
difficult to handle on the ground, ie. the Pitts as an
example. The further the tailwheel is from the main
gear the better it will handle. The Pietenpol has a
pretty short fuselage so I would vote on the 12" aft
position. Just my opinion.
Doc
--- Rick Holland <at7000ft@gmail.com> wrote:
> Hey guys, I am using a two leaf leaf spring and a
> Matco tailwheel and was
> wondering where the best position for the tailwheel
> was. The plans-built
> tailwheel show the wheel center maybe three or four
> inches forward of the
> back end of the fuselage. With the leaf spring setup
> the wheel center will
> end up around 12" behind the rear end of the
> fuselage. Naturally this is a
> negative as far as adding to tail heavyness but
> doesn't a longer wheelbase
> (distance from main gear to tailwheel) improve
> ground handling stability?
> Most factory taildraggers are setup this way for
> some reason (Cubs, 140s,
> 180s, etc).
>
> Thanks
>
>
> --
> Rick Holland
> Ribs, tailfeathers, center section done, fuselage
> ready for gear now.
>
__________________________________
http://discover.yahoo.com/
Message 5
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| Subject: | Re: Stabilizer incidence |
In a message dated 6/5/2005 2:56:37 PM Central Standard Time, lnawms@msn.com
writes:
Take a look at inflight photos of Piets and notice that many of them have a
drooping elevator! I know mine does and I have seen some others in the Brodhead
pattern that do also.
Hi Larry !! Good to hear from you.
My plane fly's straight level flight, with the elevator (flippers)
slightly low. I noticed this same thing in one of the pictures that Corky sent
me
of his first plane (NX41CC) in flight. I can turn around and watch, and if I
pull back on the stick to make the flippers in line with the stab, it pitches
up to a very nose up attitude. This is kind of baffling. It's one of the
reasons I installed trim tabs on the flippers, and took ALL the negative incidence
out of the stab. I think the weight of the flippers being behind the hinge
(no mass balance) is at least some of the reason for it. It still fly's
straight & level with the drooping flippers, though. It's in trim at 1850 to 1900
rpm indicated, but my tach reads 100 rpm to low, compared to an electronic hand
held tach. If I add 100 rpm she climbs, and if I pull 100 rpm out, she
descends and picks up speed.
Those early planes, like the Bleriot Monoplane, are the only planes I
know of with an undercambered stabilizer. It seems they carry a portion of the
weight with the stab, so the C of G can be farther aft and it would also be
much more induced drag than later designs. Just think what would happen if the
stab would stall...the nose will pitch up abruptly past the Critical Angle of
Attack, and stall the main wing.
Chuck G.
It was an absolutely beautiful evening to fly. Clear blue sky, light south
wind, mid 80's. I did the River Run, then over an hour of slow flight at about
50 mph, with the power pulled back to 1700 rpm indicated, then did a Smokin'
Fly By at Beech Field. It's amazing how just put put putting around the sky
can clear all the cob webs out of my brain !!
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