Droop Tips

[tweiss]

There has been a covert operation in the past using a completely stock 170-B. A set of extreme droops were installed and flown to experience the difference. The unmentioned test pilots were not impressed. They then replaced one droop tip with one of the original tips. Still no change. When the time was right, (darkness set in) they installed the droop tips on opposite wings pointing up instead of down. Still no change. The final test involved a second set of droop tips so they could install one pointing up and the other pointing down. Just like all the previous test flights, it flew coordinated straight and level hands off, and stalled straight forward just like stock, every time. No more breath was ever wasted at the end of a day hangar flying about droop tips.
The End

[GAHorn]

George, Your pipeline patrol experience with "Madras" wing tips is a good one. However, , you forgot to mention your experience last year flying to the convention. Remember, we both flew our planes and stopped at the same airports and bought fuel from the same FBO's. Do you also remember, my plane was faster and used less fuel OK Folks, George could never figure it out. He even thought the FBO's pumps were wrong when fueling his plane. But how could at least three FBO's be wrong? Perhaps George it was my planes STOL kit, with aileron gap seals and droop tips that made the difference Or was it my superior leaning during takeoff and cruise

Jim, that's a cute/funny comment..but I actually discovered the cause of my excessive fuel consumption. (Ordinarily my airplane consumes 7.8 gph, but on last year's trip to/from convention it averaged 8.1 gph. It turned out to be due to two malfunctions: 1) leaking fuel selector valve and 2) stuck carb float. Both items have since been repaired. (They were discovered during annual inspection on followup to fuel stains.) My airplane is back to 7.8 gph.

By the way Jim...YOUR airplane is also a shade of RED. Frank, the actual fact is...the 140A's I flew on pipeline patrol was a dark green....no kidding. They were ex-F.C. Barr patrol planes, and their company color was green. I'd never thought about that until your little jab. (We did have one ex Humble Oil and Refining 140A with 170A fuel tanks in it, but it had a bigger O-200 engine also, and was painted red/grey. The boss usually claimed it as his steed, but I flew it on some trips. It was the best performer of the fleet, but probably due to the increased hp.)

[blueldr]

What kind of a power setting do you use to burn 7.8 GPH? Thats a gallon an hour greater than mine did with the C-145 flying at about 7500' MSL.

[GAHorn]

What kind of a power setting do you use to burn 7.8 GPH? Thats a gallon an hour greater than mine did with the C-145 flying at about 7500' MSL.

2450 RPM @ 7500 MSL, TAS 105 kts, 7.0 GPH, O-300-C with one-piece venturi** and EM7655 prop. (this was derived having taken off and flown to altitude on one tank, then upon reaching cruise, switching to another tank for exactly one-hour, and then back to the first tank. After landing the second tank was refilled and took 7 gallons.

** Some operators complained that the AD-note conversion to the one-piece venturi cost them in fuel-burn, but I notice that my airplane burns what the book predicts. When I calculate the AVERAGE fuel burn incorporating the initial takeoff-climb and the incrased fuel burn of that first period, it tends to average out about 7.8 gph , and I actually FLIGHT PLAN 8 gph to be on the conservative side.

(Note: I checked my records and revised this msg post for accuracy.)

[marathonrunner]

I agree, skip the droop tips and get winglets approved. They are a good idea but I doubt with the testing involved they will be available for Cessnas for a long time. I have heard good things about wing extensions though. I have not researched the subject just from folks using them.

[GAHorn]

The only wingtip extensions with which I have any familiarity are the Flint wingtip fuel tanks. It was a Flint-equipped Cessna 337 which developed a spar crack and lost it's outer, right wing after a high-speed pass and pull up, and is causing all the hoopla about those airplanes. (Admittedly, the airplane may not have been properly maintained and certainly wasn't operated like most of us operate....but those fuel tanks are thought to have contributed.)

[marathonrunner]

There are wing extensions for Cessna models I am just not sure if the 170 is approved but I know the 180, 185 and 200 series are. I will look into it.

[marathonrunner]

Just researched it and WingsXStol has a wing extension for the 170 and for 180 hp models a gross weight increase to 2400 pounds. The address is www.wingsxstol.com or info@wingsxstol.com. Hope this helps

[907Pilot]

The 170 model is not approved for use in the USA

[HawkerCFI]

Years back an old, highly experienced crop duster by the name of Olin "Pappy" Longcoy...a well respected pilot, mechanic,
grass airport owner showed me a long wing Piper tailwheel plane of his on which he had installed smoothed and airfoil shaped
plywood panels ...on the wingtips. (careful here...this is from a less than perfect memory.)

Picture airfoil shapes cut out of 1/4 or 3/8 " plywood and attached in place of standard wingtips, but with proportionately increased thickness and chord. Pappy explained that the flat panels on the wingtips created what he called, "endplate effect". He went on to explain that one could install an endplate like his with vertical surface above and below the wing or stick the endplate upward or downward and achieve the same thing. He said that the endplate, whether installed up or down or centered controlled air that would otherwise be spilling under the wing to create wingtip vortices...and directing that air back effectively reducing drag, increasing speed, efficiency...

Of course nowadays indeed many manufacturers are installing winglets or tipsails or whatever. As usual, I'm revealing what I don't know...but I'd like very much to hear more on this from the aeronautical engineering types.

[blueldr]

Damn! I'll bet that that C-170 with the drooped tips looked neat with one up and one down. Seems like other guys always come up with the nifty ideas.

[Bruce Fenstermacher]

HawkerCFI what you remember Pappy saying about the end plates is correct. How much effect they would have is dependent somewhat on how good the original tip was. If the original design was a bad one like the symmetrical round one found on Piper Cherokees of the 60's a flat plate the didn't extend higher or lower that the air fowl would be an improvement.

I recall from my RC modeling days of the 80s a fellow demonstrated the effect of spill plates by flying an airplane with one wing full length with a round tip. The other wing he shortened by about a 3rd but put a spill plate on it. The airplane flew straight, both wings creating the same lift, because the shorter wing with the spill plate was more efficient for more of the length of the wings span.

[hilltop170]

There are many Super Cubs/PA-12s/PA-14s flying around Alaska with wing tip end plates. I don't know the basis of approval.