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rebel flaps or flaperons

Posted: Fri Feb 17, 2012 5:46 pm
by Geert Frank
Hi you all, I flew the L-20 (US Army Beaver) for a very limited amount of
hours, seemingly a hundred years ago. I do recall that it had seperate flaps
and were driven electrically. I also do not recall any ailerondroop with
flap extension. It was quite a nice aircraft and did not seem to have any
bad habits. It was also not super-STOL at least not with the standard P&W
piston engine. If I remember wrong, I am sure there are plenty of Canadians
around on this site to set me straight. Now I do have about 500 hours in
the Fieseler "Storch", post-war to be sure, I owned ten of them over the
years and I ain't that old! Now they had some mixer-assembly on that machine
and as soon as you went beyond flaps 10 degrees( with a handcrank, two
sprockets and a long bicycle chain) the ailerons started down also and once
you cranked the flaps back up past 10 degrees, up went the ailerons again to
zero deflection. 28 mph over the fence and full aileron control and designed
in 1936. No sense dreaming. I did do seperate flaps on my Rebel, because I
was visiting France a lot during that time of construction and they all said
that was the way to go. Next, not too many people were impressed with that
factory flexcable extension affair and finally it was not all that difficult
to do. You reversed the inboard flaperons and added a torque tube and some
brackets, actuated the flaps with a rod and handle or as in my case with a
flapmotor. The other nice thing is, although some effort will be required,
it is also not difficult to go back to all flaperons. I can even use the
flapmotor instead of the cable set-up to use the flap settings for the
flaperons. I have to put in the mixer assembly though since I never bothered
and use a single hinge bolt, i.e. no plate with slot, etc. I never noticed a
burble as mentioned with the prototype Elite, but there may be one. I still
do not have hundreds of hours in my Rebel, which would make me much more of
an authority. There is still something aerodynamically screwy with my
machine, 60 mph on final, any slower and I get this sinkrate, which I can
arrest with power only. And those three point landing attempts I have
mentioned before. The machine pays off much too "hard", a la Taylorcraft,
where the tail quit flying before the wings did, that got interesting. Since
I am landing now almost exclusively on my 1300 feet strip, I wheelland and
brake. My apologies to the purists, but I only have the one machine!
Here is hoping I am not boring anybody, just MY two cents worth (that is
getting to be a cliche!), Geert

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rebel flaps or flaperons

Posted: Fri Feb 17, 2012 5:47 pm
by klehman
FWIW The Beaver's big brother, the Otter, definately drooped the ailerons (but
less
than the flaps) when the flaps were lowered. I think the Beaver was similar. The
Otter had double slotted Fowler type flaps that allowed 40 degrees of deflection
to create lots of drag for landing. The lesser deflection of the ailerons kept
them near the optimum lift angle and insured that the inboard wing section still
stalled before the outboard section. (There was also a good sized wing fence in
the general area of the flap to aileron joint.) Anyway, the effect was that with
full flap, full aileron deflection would lower the aileron nearly as much as the
flap
on that wing.

Is the Elite system perhaps a little like this as well? If it uses more than 20
degrees of flap, it might be helpful for short field landings. I still suspect
that in most cases, the takeoff distance would be more limiting than the landing
distance though.

At Brampton yesterday there was mention of doing an approach at less than 40 mph
airspeed with the MacKenzie leading edge cuff STOL kit on a float equipped
Rebel.... I look forward to hearing more about takeoff performance with this
mod. Many of the newer high lift airfoils seem to have a little leading edge
droop similar to that wing cuff.

Ken

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rebel flaps or flaperons

Posted: Fri Feb 17, 2012 5:47 pm
by Charles Skorupa
That's very interesting. Seems like I recall reading in some mountain
flying book that best take-off performance flap setting is obtained by
deflecting the aileron full and then setting the flaps to match. Next time
I see the factory Elite & Super Rebel, I'll make some measurements with the
digital level and report back to the group.
- Chuck Skorupa -
----- Original Message -----
From: <klehman@albedo.net>
To: " (Murphy Rebel Builders List)" <murphy-rebel@dcsol.com>
Sent: Sunday, May 14, 2000 7:31 AM
Subject: Re: rebel flaps or flaperons

FWIW The Beaver's big brother, the Otter, definately drooped the ailerons
(but
less
than the flaps) when the flaps were lowered. I think the Beaver was
similar. The
Otter had double slotted Fowler type flaps that allowed 40 degrees of
deflection
to create lots of drag for landing. The lesser deflection of the ailerons
kept
them near the optimum lift angle and insured that the inboard wing section
still
stalled before the outboard section. (There was also a good sized wing
fence in
the general area of the flap to aileron joint.) Anyway, the effect was
that with
full flap, full aileron deflection would lower the aileron nearly as much
as the
flap
on that wing.

Is the Elite system perhaps a little like this as well? If it uses more
than 20
degrees of flap, it might be helpful for short field landings. I still
suspect
that in most cases, the takeoff distance would be more limiting than the
landing
distance though.

At Brampton yesterday there was mention of doing an approach at less than
40 mph
airspeed with the MacKenzie leading edge cuff STOL kit on a float equipped
Rebel.... I look forward to hearing more about takeoff performance with
this
mod. Many of the newer high lift airfoils seem to have a little leading
edge
droop similar to that wing cuff.

Ken

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