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Performance STOL flap testing

WanaBNACub

WanaBNACub

Registered User
Off Airport
When I made the decision to put the PSTOL flaps on I told our engineers that I wanted to do a little unscientific testing to try and see exactly what the real world performance differences are between the Performance STOL, double slotted, Fowler type flap system and the stock flaps. We have heard lots of people that are running them talk about the differences they had experienced. No one we have talked to has regretted the decision to put them on, but I have learned that "some" pilots exaggerate numbers from time to time. They made up a simple inclinometer to hang across the tubes over the back seat and I put a gopro on it to show the exact deck angle in 5 degree increments. In level flight I "zeroed" it by lining up that longer center mark with the pendulum. I also put a gopro on the airspeed indicator to show the touchdown speed. I had put 5 landings on the flaps after we installed them and then 10 landings for the video test. Since this video I have gotten used to flying them more and could improve on those numbers quite a bit. Power on stall speed went from about 30mph at 1600 rpms down to 21mph at 1600. I have had the touchdown speed as slow as 25 now with no wind.

 
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Just to DANG COOL....Few mod’s make a seat of the pants difference, Lower’d the nose as well as the stall speed. Like you said, When you get comfortable operating at the slower speeds I’m sure you will get even more out of them. Great way to demonstrate the improvement.
 
I can't wait. I am encouraging my Super Cub buddies. I may even do the installation for free.

Are you using GPS speeds, or just airspeed indicator? We can fly a stock Cub at zero indicated.
 
One thing significant is the effect on wing lift and pressure distribution with flap retraction at the end (~5:54). Flaps up tail drops now. Not like most Cubs I've owned with stock flaps.

Gary
 
I changed a PA-18A enough to get stall in no wind level flight near gross to 28 GPS. Four corner trial to correct for any wind - none noted. But I was staring at the clouds with full 50* flaps as the C/P moved forward. No way to land the plane in that attitude on 25" tires.

Now with these venetian blind flaps the C/P moves aft with deflection and I assume the runway is quite visible at low landing speeds. Excellent!

Gary
 
Nicely done Cory. You’re enjoying your new job.

I am envious of that cool sea level air.

I’d call a 4 mph reduction in touchdown speed (at least 10%) as significant. That will really cut down the landing roll. And the flatter attitude is fantastic.

How about takeoff performance. Are you seeing an improvement then?
 
BC12D-4-85 said:
I changed a PA-18A enough to get stall in no wind level flight near gross to 28 GPS. Four corner trial to correct for any wind - none noted. But I was staring at the clouds with full 50* flaps as the C/P moved forward. No way to land the plane in that attitude on 25" tires.

Now with these venetian blind flaps the C/P moves aft with deflection and I assume the runway is quite visible at low landing speeds. Excellent!

Gary
Click to expand...

Yes, the visibility is definitely the most valuable improvement. You should be able to come in at 28-30 at a flat to maybe 5 degree nose up attitude in a wheel landing and have perfect visibility. My deck angle sitting still or taxiing is around 16 degrees on 35's for a reference.
 
spinner2 said:
Nicely done Cory. You’re enjoying your new job.

I am envious of that cool sea level air.

I’d call a 4 mph reduction in touchdown speed (at least 10%) as significant. That will really cut down the landing roll. And the flatter attitude is fantastic.

How about takeoff performance. Are you seeing an improvement then?
Click to expand...

Yes I am. I love Airframes and the job fits me perfectly! Great company. Takeoff performance is also significantly better. I would guess right around the same improvement. I wish we would have marked off the runway and measured distances for takeoff and landings both. As soon as I pop the flaps at about 30mph I am in the air in ground effect and that tail is up. It comes off the ground much flatter as well.
 
Speaking of long flaps. I know of the -12 STC. but what about on an -18? Is there an STC? Seen them on a few. One I got done as a field approval (which is not the right way). Is there an STC for -18??? Well the Dakota wings come with them...


Sent from my iPhone using SuperCub.Org
 
The only current legal long flap for an 18 that I know of is the Dakota wing and several field approvals as well.
 
I thought we were talking about double slotted Fowler flaps that are STCd?

Sure, a stock Super Cub can be flown at 25 indicated and less than that ground speed. Deck angle is 45 degrees, and it is still going up. Did it today. Not close to the ground.

But a stock Super Cub stalls around 40 in the 3-point attitude. It would not surprise me at all to see 25 mph with Fowler flaps as a 3- point stall speed.

I cannot believe Husky didn't go that route.
 
If you leave power on 1700 RPM a well rigged cub will fly at 36-37 in ground effect but it is not quite 3 point attitude. The tailwheel is 1-1 1/2 ft below 31 inch bushwheels with 3 inch gear. As bob pointed out the deck angle is pretty severe and that in turn makes spot landings harder. The new flaps not only help the deck angle but also slow the plane down. They will become the next thing on the list behind a Borer prop and bushwheels.
DENNY
 
They've been the next big thing for several years!

Has anyone fitted these flaps to a Carbon Cub wing yet? When deciding on my exp Cub direction Keller flaps were a big consideration. Mitch at CC told me it couldn't be done but I don't recall why. I'd think where there's a will, there's a way. Anyone done it?

The big sell for myself was what long Pstol flaps do for a Cub with slats. No more nose to the sky attitude. It was the game changer. I knew I wanted the flaps. I didn't know the flaps would facilitate the slats.
 
A guy I know of in Washington has Keller flaps on his Carbon Cub. I'm sure Cubcrafters has his info.
 
Did not know the CC had slats. One of my dreams is to fly the Dakota slotted wing - slats would be even better, but it seems to me that things get complicated quickly with movable slats.

Surely someone is doing slots and Fowler flaps?
 
After watching that video it took me thirty minutes to wipe all the drool off of my computer. I bet these flaps would help with viability on my cub that has the thrust-line kit on it which makes it harder to see over the nose.

Eddy
 
bob turner said:
- slats would be even better, but it seems to me that things get complicated quickly with movable slats.

Surely someone is doing slots and Fowler flaps?
Click to expand...
Only installed one set, but it was rather simple. Lay strait edges under wing, set slays on straight edge and drill holes to screw on. We went extra mile and installed nut plates then. But most are just pk screwed into wing. Then open them 1 “ and drill and install a stop bushing.



Sent from my iPhone using SuperCub.Org mobile app
 
Once you know the ratio of gap to the Venturi that you want, as well as if you want the Slat L.E. Flush or lower than the wings , Like Mike said , Just a matter of putting them on square and making sure where your mounts are can carry The loads. Then you’ll forever be a believer in them being one of the single best add on mods you can do!
 
What approximate degree those flaps are aiming for?? 80 degrees, like the bottom drawing, look like a lot...







8-2.jpg


Cuzoom is also not shy on degrees...

stol-001.jpg













How much is too much ?????
 

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Performance STOL Flaps safe on nose heavy amphibious Cub?

Greetings,

We have a CC/PA18-180. Half it's hours are spent on amphibs, the other half on skis or 35". The latter is driving the desire for these flaps, but the former drives this question....

Has anyone had trouble with an already nose heavy Cub, on amphibious floats, with these flaps? Neither Wip, nor Airframes, will attest to anything along these lines.

Thanks, and Merry Christmas!
 
Olibuilt said:
What approximate degree those flaps are aiming for??

How much is too much ?????
Click to expand...

I guess that depends on how long the flaps are. My initial target measured at the aft surface was 70*. My current ratchet has 4 notches at 15-30-45-55. My preference is 45* but I may learn to like 55* in some conditions. To pull my handle to 70* would take considerable effort. I doubt it would be worth doing but I may try it. I need to cut a new ratchet arch. Might as well cut two or three and play with different notches.

What does the STC allow for max flaps?
 
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I think most amphib Cubs are out of the forward CG envelope without ballast. They seem to fly ok. I personally did not care for the CC 180 Cub. Way too heavy.
 
stewartb said:
I guess that depends on how long the flaps are. My initial target measured at the aft surface was 70*. My current ratchet has 4 notches at 15-30-45-55. My preference is 45* but I may learn to like 55* in some conditions. To pull my handle to 70* would take considerable effort. I doubt it would be worth doing but I may try it. I need to cut a new ratchet arch. Might as well cut two or three and play with different notches.

What does the STC allow for max flaps?
Click to expand...

The STC states 52 degrees for max. I know of lots of experimental cubs running way more than that. You just have to watch for it blanking out the tail if you go too extreme. I have only heard of a few instances of that so far though.
 
mike mcs repair said:
which has lead me to think before..... if a split(funneled through) design works so good for a flap, WHY NOT a split design rudder and/or elevator...
Click to expand...

I've been thinking the same thing....It's probably a dangerous habit, but fun.

Seems like it would be effective with an airfoil shaped stabilizer and the proper curve leading into the elevator.

But I get hung up on making it effective in two directions.
 
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