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Experimental Cubs & Extreme Stol Devices, Flaps,slats,sl

Wayne, I looked at the pictures , #34-37 of the Dakota Coyote on "Supercubs Galore". Your slats "fold", being controlled from the driver's seat? What are the advantages / disadvantages of this design to the fixed slat, see picture #672 (slotwing 310) and the Sumner Puttmon fixed slat? What is the cruise speed penalty with a fixed slat?

Hans :D
 
Slats

Hans, The slats don't fold, all they do is hinge up to open from the pivet point and
weathervain back down to the wing do to forward airpressure at cruise. They
are free floating on pivet point. Of corse there are stop limitors. The first slats I
had were copys of Sumner's. They worked fairly well but hurt your cruise about
8 to 10 mph. I changed the shape and gained 2 or3 mph. Later I made them lie
down in cruise and gained 2 or 3 more. The big differents between slot and slat
is with the slat you are gaining wing area, mine about 30 sq ft. Wayne
 
Wayne, my Bushmaster with a Cub Wing/leading edge cuff does quite well. However, I feel that with your slat system and a spoiler we are flying at 20mph. That spells some safe flying to me. Could your slat system be adopted to a Riblett wing that a friend of mine is building? All of this is of course only applicable to experimental Cubs, I can sense the frustrations from some true Cub drivers, limited by FAA and STCs.

Fly safe and have fun!

Hans :)
 
Slats

Hans, Yes i think the slat will work with any practical airfoil. It is attached to what
looks like cub aileron hangers that bolt to the spar. A helio has a wing that is not
that different from ribblet or tailorcraft. Even most of the big jets. It just keeps the
air laminaled to the wing at lower speeds. The spoilers work well with the slot or
slat because you don't have to change attitude to desend. The angle of attack is
where you get the slow speed. My self I am going to link the spoilers with my
ailerons. They are small because of the big flaps. They will deploy only at the very
last of the stroke on aileron movment. Only when you need the boost, slow speed
in the wind. Wayne
 
Slow flight

Peaple'
Its been kind of quiet here lately so i'm going to bring up a problem in slow flight that
few is anyone thinks about. When ever we what to show our stuff and demo our
slow flight capibilitys we pull every thing we can out of our plane to lighten the load.
On take off this is all good due to accellerating a weight to flight speed. This is not
allways true for slow flight ones in the air. Many of the striped out planes out there
are nose heavy when real light. I know this dosn't sound right at first but give it some
though. take a yard stick and tape a axle to it at the one ft mark and take two
blocks put on a scales with the axle across. Tape 10 oz. to the short end and 5 oz.
at the far end. It balances. Now move the axle to the 14" mark. The short end with
the 10 oz. falls. If you push down on the 5 oz. end look what happens to the scales.
The weight reading goes up. This is like your plane, if you are using a lot of pressure
to hold up your nose your wing is like the axle point. You are increasing the wing load.
Your wing is trying to carry more than needed. If a small amont of weight is in the
aft bagage but still in CG. it will reduce the wing loading more than enough to make up
for the weight added in the bagage. The plane will handle better on aproach and
on the ground you can get on the brakes with out nosing over. Don't worry about
take off, after you get it parked where you want it you can throw out the rocks.
Wayne
 
Stol

Is any one out there using vortex generaters with a slat or slot system. would like
to know what is being tryed in this area. I have used them with good success but
would like to learn more. Wayne
 
Just saw an article in Feb. AOPA Pilot magazine on "discontinuous outboard leading edges" Interesting read.
 
Slat mod

Jerry,
Have a new idea on gen. placement on the slat. If you see Denny in the next few
day see if he wants to get together to check this out. Do you still have a bunch of
gen. under the tape. if not I have about a hundred I could get ready. [the large]
Think it will help the low end and cause them to lay down at a lower cruise speed.
Should see ya in 10 days. Wayne

PS. the Allta burned
 
Super Cubby

Looking for imformation. Does any one have a phone number for the Tomson Brothers.
When they first built there cubby they got some numbers off the 36" tires I had on
my plane and ordered some for their plane. They came from Dunlap out of Great
Britten. I lost the info and would like to get the numbers back again. Wayne
 
Bigger leading edges?

I see the North Star web site says that they extend their leading edges back 4" past the front spar. This is supposed to help maintain the shape of the airfoil and I suppose enhance performance. What are your thoughts about this mod? Should a person leave well enough alone?

Mark
 
Leading edge

Mark , This is good question . This is something that went through the area of Alaska
I lived in during the 70's. I have done one of these mods my self and around a few
others. They look good, but we didn't gain a thing except weight. And labor. On the
one I did we lost some take off perfomance. I can't say it dosn't work for some, But I
would spend my time and money somewhere else. A while back there was a picture
of a C.C. yellow cub on the front of a magazine that showed the top of the plane in
flight and all the fabric between the ribs was balooned up to the shape they are
after with the added leading edge. So when you are under a positive load it appears
to me there isn't any need for this mod. My opinion only by what i have seen.
Wayne
 
That is a good question. I have been told by those that used to dust with J3's that a wood spar 3 would always carry a larger load than a metal spar 3. The biggest difference aerodynamically is that the wood spar LE stops well in front of the spar, allowing the fabric to dip way down between the ribs when sitting on the ground. But maybe it also ballons up higher in high lift situations?, and this "flexable" airfoil may actually be better? The wood spar Cubs are usually a little lighter, but not enough to make a real big difference in hopper load.

Also, maybe Wayne knows, Why did Piper keep useing the short LE outboard section on all the later J3's, PA11, and PA18. They went to the long LE on the J5, PA12/14, but it stayed short on the OB on the other models, there must be a reason. I asked this somewhere before, and no one seems to know.
 
Leading edge

Mark,
I don't really know the facts about the full leading edge on a cub not going all the way
out to the tip. It always looks odd when you do a wing exstenion. At one time I was
told that the full leading edge was added to help support the main spar. since the
main load is just inboard of the strut attach it may not have been needed outboard.
I don't remember who said this so , take it with a grain of salt. Wayne
 
stands to reason? that the leading edge extention would give extra support to the spar/tank bay as well as there is the prop blast over that area as well?? I have heard the J3 duster dialog before and it make a lot of sense. Also I think that the flexibility of the grade A/nitrate may have allowed this, the adhesion problem with buturate/ceconite especially if the fabric doesn't get saturated caused in the 70's a lot of fabric/dope failures?

Also Ureathane painted cubs would crack badly on the ribs just aft of the spars if you remember? (perhaps fixed now with better flex additives?

By the way do you know how much less a std. cub wing weighs versus a dakota wing?

Tim
 
Leading edge

Had a freind build an over sized exper. cub in Ak. during the 80s. It had huge flaps
and drooping ailerons. On rotation with flaps on take off the fabric between the ribs
would baloon up a good 1/2" above the ribs. If memery serves I think the ribs were
about 20" apart. I know this wasn't a cub wing but the point being made is the same.
Wayne
 
Thanks Steve! I have a friend with a severly damaged wing and his concern was;, would he have to build the wing with the "old" sty ribs to balance with the other one? Awefully time consuming to repair a lot of damaged ribs.

Tim
 
Tim, I've never weighed a cub or any other airplane that was even close to being the same weight on both main scales. The last one I weighed was about 60-70 lbs difference. Don't ask me why, I have yet to figure it out. One suggestion though. The Univair ribs can be disassembled and installed without removing all of the ribs and disassembling the whole wing. I don't know how bad the wing is but they make the repairs go alot quicker in this case.
 
Door chanel

Question Guy's,
Talking about the peices of chanel that covers the tubing around the door frame
on a supercub. Has any one come up with a good methed of getting a good coating
of paint under. If it is prepainted it gets burned when tacking on the chanel
Wayne
 
Tom Hegy put lightening holes in his Experimental PA-12. There was a good article in the Cub Club Clues w/pictures.
 
Wayne or any one
If after we install all of the STOL mods to the wing and we get it flying 20% slower than stock, does the tail surfaces have enough area to still control the SC in slow flight, or should we increase the tail area? I have just began building a PA12 and would like to make a few of the mods to the wings.
Eddie
 
Tail feathers

Eddie,
The SC tail should be good for what you want. The only time we have come up
short is with a nose heavy airplane with large flaps and droop ailerons. These
flaps and ailerons cause a big pitching moment with the power off. But this is a
good Question, the slower you fly the less affect your controls will have. Wayne
 
Thanks Wayne, I have another question for you. I have been doing some studies on wing slots myself and I understand the theory of the slot, but I haven't found anything on the size of the slot. What is the ratio of the lower wing slot gap to the top? I understand the top needs to be smaller to give it a venture effect and energize the boundry layer, but I haven't found any figures on it. Also would it be desirable to have a gap between the flap and the wing when it is in the down position to help prevent the flap from stalling?
 
Eddie, Wayne,

Good posts great information and questions, I have the same question? gap between the flap and trailing edge of wing when the flap is down? The PA12 has a much larger "flap gap" (now gap seal from the factory??) I would like to hear the explanation for this difference?

Thanks

Tim
 
Flaps slats

Eddie Tim,
On a 18 there is a trailing edge peace of alum. that turns the air down over the top
of the flap. Jerry Burr has done quite a bit of testing here and I've done a lot of
studying of his vidio's. I beleave this is important area in controling not only the air
on top of the flap but the air forward of the flap on top of the wing. Maybe we can
get a little input from Jerry. He has these peaces of alum. the full length of his wings
and we all know there is nothing on his cub that dosn't carry it's weight.
As for the slats the inlet and outlet sizes are 4 to1 or 3 to1. This can very quite a
lot and still work. I my self am closer to 2 to 1 but can only do this because of the
way they move. If they were fixed in position cruise would be 65 to 70 mph. Not
practictal. Wayne
 
Slat

Eddie,
That speed was refiring to my slat and when it is fully open. With the fixed
slats and normal opening I only lost 8 to 10 mph. That was still with my slat and it
is larger than most. I don't know the numbers on the other slats out there. The way
I build and use the slat has changed over the years and now lose only 2 or3 mph.
we have three 18 type out there that cruise from 95 to 105 depending on HP.
They all have long gear big tires and long wings. The fastest has gear that is 14"
longer than standard and 30" tires. Wayne
 
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