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Un-drooping the droop tips

Stall Speeds

Jerry: you're always a gentleman in the way you reply, even though I like to jack you up sometimes. It is done in a fun spirit and I take no offense to your comments.

Something we (the group) might want to do for the fun of it is have the guys (and gals) check the wind direction at their strip and go up and slow fly their planes until it stalls in both directions (into and with the wind). Lets all do it with full flaps or what configuration works best on your plane. Don't even look at your airspeed indicator. Turn on your GPS and write down the number (ground speed) where it stalls. Do it several times in both directions to get a real number in each direction. Make sure you note the track direction and turn exactly 180 degrees for each test. Add your stall speeds (GPS) together and divide them by 2 and post them to this thread. We would need the tempature and humidity as well to get apples to apples comparison but for this lets just take the raw numbers and compare.

I think most guys if they picked a stall number (mph) before the test and then went up and did this exercise, I think they would come away suprised at how far off they are.

I heard of one highly modified (wings) PA-18-180 that was reported to stall at 25 mph. A well known Super Cub geru took it up and turned on the GPS (no one else had up to this point) and tried it in both directions and came back and reported it really stalled at 40 mph, not 25 mph. Let's not kid ourselves. Do these mods work and by how much? Say my stock winged PA-18 stalls at 40 mph and the highly modified winged PA-18 stalls at 37 mph, will this really make a big difference. Would it get us into places a stock light Cub could not go, or would big balls (sorry ladies) make up the 3 mph difference.

I am an old motocross and snowmobile racer and have no adversion to modifing something as long as it makes a REAL improvement. If the wing mods make a real difference in how I can use my plane I will be the first to install them. Take care. Crash
 
Slow test

Hi Crash. A great idea. The problem that I have seen in the past with it, is that not everyone has a VSI. And a Cub will always fly slower in a climb than on the straight and level. I have flown side by side with other Cubs and the first thing they do is start climbing. If everyone would set the alts. to 29.92 and then climb to say 1500' and stay in (level) flight then it would be a fair test. The temp isn't much of a correction. I have never had a correction over .7mph. Most of my testing is done in the cool early morning still air. I have a VG test to do in the am. Will give it a try. The other problem is a power setting. I have always used 2000rpm at 200lbs over gross to do all my testing. The trick would be to be light and use all the power you can (without climbing) Jerry. :)
 
so jerry, are you saying that the wing will stall at a slower speed at the same angle of attack when the plane is climbing, rather than straight and level. or are you saying that climbing changes the angle of attack that the wing stalls at. or something else.
 
Stuff

Hi Flyer. It's a lot more simple than that. You stall slower with power than without. You can carry full power in a climb, but not in level flight because you will climb. You are limited as to the power you can use without climbing.
Crash. OK here are some numbers. I ran 4 directions as I wasn't sure of the wind direction. It appears it was favoring the south. The temp was 58deg and pressure alt was 1500'. East 32.3, 28.3. North 39.7, 39.6. West 32.8, 32.7. South 23.3, 23.0.
The biggest variation seemed to be to the east. That is maintaining level flight just before the break. That is with 24 gallons and my test gear.
When I get through with the current testing, I will try it light.
:) Jerry.
 
Stall

Jerry: Looks like your plane will stall at around 32.96 mph. Well that is pretty good. Mine won't, I can that say even before trying it. But it is a heavier PA-18 and J-3's are known for their great slow flight. What is your gross?

I was looking more at a landing type configueration. Nose a little high, full flaps, a little power, myself and 10 gallons of gas. The typical short field slow approch. How slow will the plane go and still stay in the air. Crash
 
Slow

Hi Crash. I have a great problem with the subjective evaluation of the term ( a little ). If it's landing you would like to look at, how about in ground effect. Same thing two directions down the runway without touching. Whatever it takes to do it. My paperwork still says J-3 so my gross is 1280lbs. :) Jerry.
 
A little

Hi Jerry: The "a little nose high" comment was to try to get a real number on stall speed and do it some what the same. Every plane will pitch a little different with flaps on. Mine with full flaps and 2000 rpm will want to climb. To keep it simple lets just try to turn our best effort. I like how you did four directions and two stalls in each direction. If I get some time I will go out and try it and report back. I'm guessing I will come in around 37 to 39 mph by adding up 8 stalls (two in each direction) and dividing by eight. Crash
 
Re: Slow test

Jerry Burr said:
If everyone would set the alts. to 29.92 and then climb to say 1500' and stay in (level) flight then it would be a fair test.
Click to expand...

I tried that once years ago!! Has a tendency to leave Super Cub parts scattered across the countryside at this elevation. :-?
 
HI

SD2. Yes you are right. Forgive me. Being at sea level all my life, I never gave a thought about the folks at Denver. You present a very good case, in that what has always worked for me, is not good for someone else. I owe you a dinner. Thanks. :( Jerry.
 
Stall Speed

Hi Jerry: I went out and did the test using my Garmin 196 flying true north, south east and west. I kept it a 2,000 rpm, myself, 12 gallons estimated, and normal gear. I slow flew it down until it stalled each time (eight total, two each direction). I came up with 39.0 mph average using the GPS speed to the tenth of a mph where it stalled. I was at 2500' during the test and it was 67 degrees. I might be able to get another one to two mph slower if I were to do the test at a lower altitude and do it in the morning when it's cooler. Anyway, the bird feels good and solid with no weird tendencies, I like it!

Take care! Crash
 
steve said:
The previous owner of my plane had droop tips installed and I would like to get rid of them. What I am wondering is, how big a job is this? Did they actually cut off the wing bow to install the droops?

Steve

Have you tried calling the mechanic who did the install of the droop tips?

After all, it is a Supercub, bright red and white, on floats, droop tips, in the middle of Kansas. How many planes like that would a Kansas aircraft mechanic work on his lifetime. He would surely remember what internal changes he made to the wing.

Paul
Click to expand...
 
Paul,

Actually, I think a guy from CC flew to Kansas and installed them on my plane and a yellow husky.

sj
 
Numbers.

Hi Crash. Got some new numbers. It was damp and foggy this morning. The airport was fogged in so I went up river and used a bar. Then the fog caught up with me and I had to sit on the bar for a couple of hours and eat wild blackberries. Tough life. The really neat part was the contrails off of the prop tips. I had the video set up on the gps so no pictures.
I dumped a lot of weight so was basically 10 gals and video camera and tripod. The non climbing slow flight at 1500' was slightly less than yesterday mainly because of the weight difference. North 31.5, 29.4 West 24.4, 24.8 South 29.3, 27.7 East 35.8, 36.4 . Big difference was the wind out of the west. That's 29.9 or 30mph by my figures. The ground effect speeds were West 32.1, 31.9 East 30.8, 30.3 . Lot less wind between the trees. That should be 31.2 ave. I'm interested to see what your ground effect speeds are. I have always felt that the tips gave me ground effect all of the time. Which is why I wasn't surprised to see a big difference between the two non-climbing speeds. Off to breakfast. :) Jerry.
 
Tips

Hi Steve. I have been watching the comments and trying to stay quiet about your tips, but we all have limits. Of all the 5 styles of tips I tested your CC tips most closely resemble the Ferguson (Hot Tips, Booster Tips) out of Texas. They turned out to be worse performers than just the square flat tip. No tip and Fergusons were at the bottom of the list. If you don't like the droop, Sullivans will screw right onto your existing tip rib. They will still give you the additional two feet of span without the droop. Sullivans were within a mile an hour of Demers in stall speed. Check them out. :D Jerry.
 
Thanks, Jerry!

This has been a very interesting thread!

sj
 
Stall Speeds

Thanks Jerry, now maybe we can have some of the other PA-18 guys weigh in on this with their stall speeds so you don't make me look so bad. :oops: Although this is really an apples to oranges comparision between our two planes. It would be interesting to get some PA-12's, PA-14's, Huskys and light PA-18's involved in this thread. Gunny, where are you at when I need you. Steve take that amphib out and stall it a few times and report back (if you can). Take care. Crash
 
Our '56 SC came with Demers Super Tips and stock ailerons. The plane
was ponderous in roll and seem to run out of aileron in ground effect. We
removed the tips and went back to stock round tips in the rebuild. The
hardest part was locating the original hardware. Bending the spar tips back
was easy. They don't have to move far. The surprise for me, was how heavy the Super Tip parts are. The spar web plate is much thicker than the
original spar web material and the 1/4 " plywood end ribs are hefty. Just tie
barbells to your wing tips and save the expense of droops if you want to find
out how they feel!

Ron
 
Tips

Ron old boy, I hate to drop this on you. But that wasn't a STC'd Demers set up on your airplane. It sounds like someone put a Demer tip on a Ferguson wing extension. If it was Demer you wouldn't have had anything to straighten. The wings would have been the correct length for the ailerons and it would have had the correct roll rate. You did good to get rid of that combination. Take Care. Jerry. :)
 
Weight

I took everything off ONE wing and weighed it and it was around 10 lbs with plates, angle brackets, bolts, nuts, screws, washers, and tip. My neighbor heard I was taking them back to stock and came over and bought them (both wings) from me. I in turn purchased a new set of stock Dakota Cub wings. A win - win for both of us! :D Crash
 
Diggler is at it again.

Hey Diggler. You rascal. You know as well as I do that every tip, droop or not has different hardware and weights. You are being non-specific for a reason. Who are you trying to stir up this time?? :wink: :wink: Jerry.
 
#'s

Hi Kase. Mine won't scroll up enough to see the numbers on the GPS. Hey did you get those wheels? Jerry.
 
Jerry, I think that is a transistor radio, not a GPS. He talking airspeed I think...

sj
 
I went out this evening and flew 2 directions as slow as I could and maintain the same altitude. 31 and 52 mph at 4800 msl per the gps. I tried it in ground effect and got 38 and 49, wind was about 4-5 mph x-wind about 30 degrees from direction of flight. The atis said density altitude 5800 at a 3600 elev airport.
 
My airspeed will indicate zero when its hot. In the winter time it appears to be more accurate on the low end. The picture 2 post up was taking when it was cooler out.


 
Anybody ever try a helicopter airspeed indicator? I have one that goes down to zero I keep meaning to experiment with.
 
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