Washout?

I picked up a project that was supposed to be built with 1.5 degrees
of washout towards the end of the wings. The builder unfortunately
built them without washout, because while his workmanship was actually
quite good he was worried he wouldn't be able to match the wings and
one would drop in a stall.

Before I rebuild the wings, what disadvantages am I looking at keeping
things as they are besides the whole wing stalling at once? Any other
aerodynamical problems? And could I cheat a fix by using VGs on the
outer part of the wing?

wrote in message
...
I picked up a project that was supposed to be built with 1.5 degrees
of washout towards the end of the wings. The builder unfortunately
built them without washout, because while his workmanship was actually
quite good he was worried he wouldn't be able to match the wings and
one would drop in a stall.

Before I rebuild the wings, what disadvantages am I looking at keeping
things as they are besides the whole wing stalling at once? Any other
aerodynamical problems? And could I cheat a fix by using VGs on the
outer part of the wing?

Or put a "triangle" shaped addition on the leading edge of the wing's root,
to trip that portion into stall, first.

That's all anyone is after with washout. Keep the outer portion flying,
while the root is stalling.

If it were me, I would probably do a bit of both! g

Advantages of keeping the wing with no washout is that the whole wing will
be lifting at cruise, instead of throwing away part of the outer wing's lift
with added washout.
--
Jim in NC

On Sun, 23 Mar 2008 15:15:35 -0400, "Morgans"
wrote:


wrote in message
...
I picked up a project that was supposed to be built with 1.5 degrees
of washout towards the end of the wings. The builder unfortunately
built them without washout, because while his workmanship was actually
quite good he was worried he wouldn't be able to match the wings and
one would drop in a stall.

Before I rebuild the wings, what disadvantages am I looking at keeping
things as they are besides the whole wing stalling at once? Any other
aerodynamical problems? And could I cheat a fix by using VGs on the
outer part of the wing?

Or put a "triangle" shaped addition on the leading edge of the wing's root,
to trip that portion into stall, first.

That's all anyone is after with washout. Keep the outer portion flying,
while the root is stalling.

If it were me, I would probably do a bit of both! g

Advantages of keeping the wing with no washout is that the whole wing will
be lifting at cruise, instead of throwing away part of the outer wing's lift
with added washout.

big john and morgans have it with the triangular strips.

you just tape them on and keep shortening them until you have the
stall chracteristics you need. then you replace the temporaries with
permanent ones.
make both sides identical.
work out where the 3 degree angle of attack neutral point is on the
leading edge and stick them there.

Stealth Pilot

On Mar 24, 7:03 am, Stealth Pilot
wrote:
On Sun, 23 Mar 2008 15:15:35 -0400, "Morgans"



wrote:

wrote in message
...
I picked up a project that was supposed to be built with 1.5 degrees
of washout towards the end of the wings. The builder unfortunately
built them without washout, because while his workmanship was actually
quite good he was worried he wouldn't be able to match the wings and
one would drop in a stall.

Before I rebuild the wings, what disadvantages am I looking at keeping
things as they are besides the whole wing stalling at once? Any other
aerodynamical problems? And could I cheat a fix by using VGs on the
outer part of the wing?

Or put a "triangle" shaped addition on the leading edge of the wing's root,
to trip that portion into stall, first.

That's all anyone is after with washout. Keep the outer portion flying,
while the root is stalling.

If it were me, I would probably do a bit of both! g

Advantages of keeping the wing with no washout is that the whole wing will
be lifting at cruise, instead of throwing away part of the outer wing's lift
with added washout.

big john and morgans have it with the triangular strips.

you just tape them on and keep shortening them until you have the
stall chracteristics you need. then you replace the temporaries with
permanent ones.
make both sides identical.
work out where the 3 degree angle of attack neutral point is on the
leading edge and stick them there.

Stealth Pilot

The planform of the wing has a huge effect on stall behavior.
If this is a rectangular wing, like a Cub or Champ, washout isn't
usually necessary since the stall will start at the root anyway. If
it's tapered or elliptical, washout is necessary to get the stall
started at the root. It will start around midspan otherwise, and
aileron effectiveness at low speed is lost. Some aerobatic airplanes
have tapered or elliptical wings with no washout, but they're not for
the average weekend flier. The stall characteristics can be very
abrupt to get quick snap rolls and so forth.

Dan

wrote in message
...

The planform of the wing has a huge effect on stall behavior.
If this is a rectangular wing, like a Cub or Champ, washout isn't
usually necessary since the stall will start at the root anyway. If
it's tapered or elliptical, washout is necessary to get the stall
started at the root. It will start around midspan otherwise, and
aileron effectiveness at low speed is lost. Some aerobatic airplanes
have tapered or elliptical wings with no washout, but they're not for
the average weekend flier. The stall characteristics can be very
abrupt to get quick snap rolls and so forth.

Even with washout, the Emeraude (elliptical planform - 23012 airfoil) will
stall fairly abruptly. Like, at 50 you're flying - at 49 you're not.

Rich S.

Rich S. wrote:
wrote in message
...


The planform of the wing has a huge effect on stall behavior.
If this is a rectangular wing, like a Cub or Champ, washout isn't
usually necessary since the stall will start at the root anyway. If
it's tapered or elliptical, washout is necessary to get the stall
started at the root. It will start around midspan otherwise, and
aileron effectiveness at low speed is lost. Some aerobatic airplanes
have tapered or elliptical wings with no washout, but they're not for
the average weekend flier. The stall characteristics can be very
abrupt to get quick snap rolls and so forth.


Even with washout, the Emeraude (elliptical planform - 23012 airfoil) will
stall fairly abruptly. Like, at 50 you're flying - at 49 you're not.

Rich S.



That's a function of the wing planform - not the airfoil.

Thanks for all the advice and discussion. Looks like stall strips
could be the way to go. I think I'll experiment with the VGs too.
BTW, the wing is rectangular.


Or put a "triangle" shaped addition on the leading edge of the wing's root,
to trip that portion into stall, first.

That's all anyone is after with washout. Keep the outer portion flying,
while the root is stalling.

If it were me, I would probably do a bit of both! g

Advantages of keeping the wing with no washout is that the whole wing will
be lifting at cruise, instead of throwing away part of the outer wing's lift
with added washout.

big john and morgans have it with the triangular strips.

you just tape them on and keep shortening them until you have the
stall chracteristics you need. then you replace the temporaries with
permanent ones.
make both sides identical.
work out where the 3 degree angle of attack neutral point is on the
leading edge and stick them there.

wrote:

Thanks for all the advice and discussion. Looks like stall strips
could be the way to go. I think I'll experiment with the VGs too.
BTW, the wing is rectangular.

See....
http://selair.selkirk.bc.ca/aerodyna...l_Pattern.html

Since the AOA is reduced by the up-wash we must predict that a
rectangular wing will have a greater effective angle of attack at the
root, and therefore will stall first at the root.

YMMV.

- Barnyard BOb -

Barnyard BOb wrote:

wrote:


Thanks for all the advice and discussion. Looks like stall strips
could be the way to go. I think I'll experiment with the VGs too.
BTW, the wing is rectangular.


See....
http://selair.selkirk.bc.ca/aerodyna...l_Pattern.html

Since the AOA is reduced by the up-wash we must predict that a
rectangular wing will have a greater effective angle of attack at the
root, and therefore will stall first at the root.

YMMV.

- Barnyard BOb -



Which brings us all back to the question What Is It???
Rectangular wing or soemthing else?

Richard

--
(remove the X to email)
cave page at:
http://www.home.earthlink.net/~cavelamb/index.htm#top


It's never too late to be
the person you might have been.
George Elliot

On Tue, 25 Mar 2008 07:00:32 -0700 (PDT),
wrote:

Thanks for all the advice and discussion. Looks like stall strips
could be the way to go. I think I'll experiment with the VGs too.
BTW, the wing is rectangular.

As this is not where they are usually attached and the effect will
probably be greater toward the tips than at the roots I would think
you'd need to be very careful to make certain the effect was the same
on both wings. You don't wan't one wing stalled more than the other
with one having a more pronounced effect than the other ...unless you
are into aerobatics.


Or put a "triangle" shaped addition on the leading edge of the wing's root,
to trip that portion into stall, first.

That's all anyone is after with washout. Keep the outer portion flying,
while the root is stalling.

If it were me, I would probably do a bit of both! g

Advantages of keeping the wing with no washout is that the whole wing will
be lifting at cruise, instead of throwing away part of the outer wing's lift
with added washout.

big john and morgans have it with the triangular strips.

you just tape them on and keep shortening them until you have the
stall chracteristics you need. then you replace the temporaries with
permanent ones.
make both sides identical.
work out where the 3 degree angle of attack neutral point is on the
leading edge and stick them there.

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