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

Tim, note how much the ailerons get deflected up in cruise. I am curious. It was necessary to rig both ailerons quite a bit down with wickerbills on the ailerons. I removed them eventually and did not reinstall them to the ailerons.
 
I suggested to Tim that he not put wickerbills on the ailerons because of the reflex, and I don't think he did.
JimC
 
No I did not put them on the ailerons after reading about the reflex. So far so good I like the way the airplane feels with them.

Tim
 
Tim said:
As long as this thread was brought back to life, Last week I put wickerbills on my 2+2, with no flaps I need all the help I can get. Over the years I'v talked to Dave Calkins and recently, Jim C. and decided to give them a try. I only have an hour and 15 or so landings and it was a little gusty at the time. I do feel a difference when slow and I think it cut my cruise speed some but not much. I put them from the fuselage to the aileron and from the aileron to the wing tip. I don't have any numbers yet but the seat of the pants feel is very noticeable. I used .040 3/4" X 1" with the 3/4 hanging down. Tomorrow the sun is supposed to shine and not much wind so I'll give it a go and try to get some numbers. And some pictures
Click to expand...

The underlined sentence confused me on the first read.

So do you have a short wickerbill from the outboard end of the aileron to the wing tip?
 
Im asking if the short wickerbill near the tip is worth the cruise drag.
how long is this wickerbill? can you quantify its performance increase and cruise speed reduction? thanks
 
Tim can tell you the exact length. To quantify it, I'd need a few parameters on his specific plane. Qualitatively, I'd expect it to cost him roughly about a tenth or so of a mile per hour in cruise.

Since the inboard wickerbills are loading his tips more heavily than before, the purpose of the outboard wickerbills is to increase the circulation on the outboard wing and defer the tipstall. Wthout them and with the inboard wickerbills, the asymmetric tipstall break can get nasty. It's a safety issue.
 
Still haven't got any good numbers. Today I flew about an hour and a quarter north to a friends with a pretty good head wind so don't know on cruise speed. All I know so far is it feels better on landing.

Tim
 
Jim, it was round tips. I did wickerbills on ailerons, then took them off. That thing had no problem. It was sweet.

Have you found nasty habits without a device near the tip? what kind of habits?

Tim, what was your airspeed compared to before wickerbills? Headwind or not, your cruise airspeed before and after wickerbill installation is a valid number.
 
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Well, the only nasty habit I'm aware of is the rather substantial potential to stall one wingtip and aileron at low altitude with high power settings and high angle of attack while the other wingtip and aileron remain unstalled. the consequent abrupt drop of one wing can be entertaining if you don't have a lot of altitude to play with. I prefer (when feasible) that the wingroots stall before the tips.

Headwind doesn't make any difference to cruise measurements, but the turbulence often associated with winds sure does.
 
Flew an hour and a quarter home today. At 2500 and 23 inches I was seeing 85 to 87kts (indicated) at 3500ft. That's just about what I see without the wickerbills. I'm sure they scrub some speed off, but damn little. I'm so impressed with the way the plane feels in slow flight, and when landing, I'm going to leave them on. I think I'll leave them on for 50 hours then take them off and see how the plane feels then.

Tim
 
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Finally after another foot of snow and high winds for the last few days I FLEW C-FMHF for the fist time YAHOO!! I didn't do any stalls ect, just flew around for an hour break'en in the motor. it flies great what a monster! cruise with the catto 86/40 was 112mph climb at 75mph gave me 1500fpm and the engine ran smoooth. I"ll post some stall numbers soon
 
I know I need flaps but you guys are making me think about wickerbills again. The extra weight and complexity of flaps makes me go back to the no flap mind set...I've gotta fight it off and build flaps!
 
Dave Calkins said:
go with flaps.
Click to expand...

See....I knew I was right!!

I bought ribs and they just arrived yesterday and the are pretty nice. I'm going to use the aileron ribs as a model and make the flap ribs out of .032 instead of .020 they used for the ailerons and use a torque tube to operate them with an overhead handle. I'm thinking of using 3/8" rod ends for hinges but I haven't run that by my IA yet so my idea might change.

Keep me on the straight path Dave!
 
Place the hinge point below the flap, like a Super Cub. This way when the flap moves downward a gap will open up between the flap and the wing. This gap will act the same as slots on the leading edge by smoothing the airflow over the top of the flap thus delaying the flow separation. This generates more lift at maximum deflection.
 
That's a good thought Sky. I never really thought of it that way...adding lift by keeping the airflow tight against the top of the flap. That warrants more thought and research...Thanks!!
 
Lowrider said:
That's a good thought Sky. I never really thought of it that way...adding lift by keeping the airflow tight against the top of the flap. That warrants more thought and research...Thanks!!
Click to expand...

My Cub's flaps are 110" long. I took great care to make a gap closing fairing, along the top trailing edge, (when retracted) out of balsa wood and fabric. This has nice smooth flow along the cove of the wing to a sharp trailing edge. As a result I seem to be getting good slot effect action over the flaps. The lift of these flaps is so great with the power off that it embarrasses me. The plane could use spoilers to help it come down. I tried increasing the maximum angle. It still floats. That is telling me that the slot is helping the air stick to the flaps. I haven't tried tuff testing.
 
Flap ribs out of .032 is a bit heavy 2024 t3 .020 is plenty strong and a lot lighter.
 
cub12 said:
on our metro's their are VG'S on the flaps to help
Click to expand...

I tried this. No gain was realized. Jerry Burr concurred that the flow through the slot is already so turbulent that organizing it with VG's and causing it to make the curve to follow the back side of the flap was unlikely.

Some type of curved device, or what Skywagon did may have a better effect. Skywagon, do you photos of your trailing edges?? I would like to see that. Did you test with it and without it?? what results?? Thanks.D
 
just got down from doing some stalls and slow flight, It feels really nice at 50mph the cuffs work well. However i could not get the plane to stall with flaps up or down, flaps up it started to sink at about 40 and down was about 37. compared to my other smith 12 this one is nose heavy even with the engine mount pulled back 4",light weight starter and alt,catto prop, i am landing with full nose up trim and the stick all the way back. I have VG's under the tail plus the little fins by the stab. I am thinking cubcrafters gap seals? i think the plane should fly slower if i had more elevator.even at 40 it did not buffet good control and no tendency to try and drop a wing.That being said cruise is way faster then i expected. also i the main wings i have the VG's, fences, and gap seals on the top for both flap and aileron and the cuff on the out board 8' of wing so what should be a realistic stall speed?thoughts please.Thanks
 
DW said:
Flap ribs out of .032 is a bit heavy 2024 t3 .020 is plenty strong and a lot lighter.
Click to expand...

.020 just looks so flimsy....OK for ailerons but I thought there was a need for heavier on flaps when I want 40 degrees.
 
Dave Calkins said:
Some type of curved device, or what Skywagon did may have a better effect. Skywagon, do you photos of your trailing edges?? I would like to see that. Did you test with it and without it?? what results?? Thanks.D
Click to expand...

Dave, Send me a pm with your E mail address. I'll scan some photos to you. They are film pictures which I have been unable to post here. No, I did not do a before and after test as they were done during my building process. They are similar to Piper's shape except they have a longer more sweeping arc. It would be interesting to tuff the flaps with yarn and mount a camera on the tail to see what happens. The lift is so great now that I suspect that the airflow is doing a good job of sticking to the flaps.
 
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