Flaps....again

[Nefj40]

So I'm building the F22 Forrest had. Aluminum sparred wings. A friend spoke to Mackey for me, and a LE cuff is a definite. I'm still in the process of acquiring parts, but now is the time to be making the decision on flaps. It's already set up for what looks like a Cessna flap handle between the seats. Not going to waste my time with the plain flap that Taylorcraft put on the 22. After reading a lot of scientific papers, I just don't think that they are worth the effort and weight when a simple removable gurney will do just about as much. Early Austers had a split flap and I've read papers that state that they are more effective than a plain and I've seen some Auster stall numbers down in the 20's...believable? I don't know.

So far, Artic tern has what I'm most curious about. Fowler/semi-fowler. Does anyone on this board have any experience with that type of flap on a 23012 airfoil?

[PA1195]

Re: Flaps....again

I've been around Arctic Terns for years. Rode as a passenger twice. Once with Don Shultz and later Colin Conkle. Bill Diehl who developed the Tern from the Interstate used readily available NACA online data to design the semi-Fowler flap on the Tern. It's more effective than the plain flaps = effective being lift via the wing>flap slot. Current version: http://www.interstateaircraft.com Give them a call for further info.

However...bang for the buck a plain flap does well and is better than none for lift and drag. Cessna dropped a reported stall speed 3 mph going from a plane flap on a C-170/170-A to the slotted flap on the C-170B. Again however the semi-Fowler has larger profile/flat plate area than the plain flap, and requires (I assume) substantial stress engineering to safely transfer the loads into the wing.

Gurneys work for increasing lift but at a constant penalty of drag. Some reports beyond the readily available online theoretical analysis:

http://www.supercub.org/forum/showthread.php?22148-Gurney-Flaps-(again)

http://www.supercub.org/forum/showthread.php?35321-GURNEY-FLAPS-WICKERBILLS-testing-data-and-photos

Leading edge slots have been tested on a Taylorcraft airfoil: https://ntrs.nasa.gov/archive/nasa/c...9930083935.pdf and http://www.dtic.mil/dtic/tr/fulltext/u2/a801134.pdf Similar to the design on the Stinson line it can afford better aileron control in some modes. Might be easier than the fixed slats.

Another option may be the Dakota Cub wing design with a fixed LE slot: http://dakotacub.com There's a few around here and the owners appear to like the performance as the profile drag in cruise is less than a slat.

A slat is quite popular now with Mackey-type experimental wings on a variety of aircraft like the former Austers. Useable AOA is increased but calls to question the utility. Without extended landing gear it's not really useable for takeoff and landing over say simple mods like VG's or the fixed slots above.

The best example of a leading edge slat (moveable in flight) and semi-Fowler flaps with the 23012 airfoil is the Helio Courier line. They have long landing gear and enlarged tail components to control the wing which the Taylorcraft doesn't. Plus a slow turning long geared prop on later models to provide thrust.

The Austers had a slat I believe (and flaps) and were able to hang on the wing's leading edge long enough to get the stall reported. But then what? Can't hardly land a Taylorcraft at that AOA.

My initial preference would be the F-22 wing with the flaps Taylorcraft designed and VG's. Speed and slow flight at useable AOA. Beyond that and the flight characteristics would be truly experimental. Adding a slot to the 23012 has been documented (search) and might be an option if speed and control are important. The F-22 flaps look ok to me : https://abpic.co.uk/pictures/view/1430083 and the engineering is done.

Then you could hang a Dakota Cub wing on a Taylorcraft fuselage. That's been done with stock PA-18 wings. Just depends on what experiment you want to pursue.

Just some random thoughts,

Gary

[Robert Lees]

Re: Flaps....again

I have flown the F22 that was flown across the Atlantic to the UK (N221UK, later G-BVOX, now wrecked). The only benefit of the flaps was that the flap lever (more like a Piper lever or Mooney Johnson bar rather than a Cessna one as reported by the OP Dave) is that it gave somewhere to rest your elbow on, whilst operating the throttle .

The flaps reduced the stalling speed by about 2-3 mph, which was not worth the weight and complexity. Flaps were put in to compete with the perceived student training market that Cessna and Piper had effectively buttoned up.

So don't put flaps on your experimental F22; I would eliminate the weight and have a plain wing like all the others.

Rob

[Robert Lees]

Re: Flaps....again

A bit more:

This F22 (pictured above) had aluminium "gap seal" fairings above both ailerons and flaps; these worstened both the roll rate and flap effectiveness. The poor roll rate might have also been adversely affected by the heavy 30USG per side fuel tanks, installed for the transatlantic ferry flight.

I have flow several Austers with the split flap; they are more effective; pure drag, but the overhead mechanical operating lever takes some getting used to.

Rob

[PA1195]

Re: Flaps....again

Interesting observation Rob. it sounds like a similar scenario to the Bellanca 7 and 8GCBC's simple flap design. Drag flaps at best especially with the wing>flap gap sealed. Lift can be slightly improved with the removal of the seal. Aileron seals were employed by them to allegedly improve roll rate. There was some lift available but nothing like Cessna's Para-lift flap design. They do drop nose angle at the same lift on landing which can be beneficial. On floats they can unstick the plane on takeoff if kept at 14* deflection...any more adds drag and little lift.

VG's are effective in my experience...better control response and higher AOA. The increased AOA is best left unused and kept as money in the bank should relative wind suddenly change.

Gurney's on a 23102 can increase both lift and drag: http://www.dept.aoe.vt.edu/~mason/Ma...A2007-4175.pdf Maybe have them removable and available to install when needed while speed and range aren't a concern

Edit: I went around this tree in 1974-5 with my first Taylorcraft that had CAP's 85 and GW STC. I ended up changing it out for a PA-18 which served my needs better. Today I have a modified T with VG's and that's good enough for my Sport Pilot needs. If I wanted true STOL I'd get something else. Building isn't worth the cost in time and money.

Gary

[Nefj40]

Re: Flaps....again

I already have a flying Tcraft to get me by while I'm building so that's not a issue. I flew a buddies PA18-135 last year, while the performance is impressive, I barely fit in the thing. I'm just too broad shouldered. I'm aware of the slat Mackey builds, but that's a little more extreme than I care for. I might just call Wayne and see what he says. I know that he really likes the Tcraft wing and I think he's currently working on something for it.

[PA1195]

Re: Flaps....again

Some discussion by Wayne Mackey re Taylorcraft: http://www.supercub.org/forum/showth...he-Taylorcraft Yes his advice would be the best given his experience.

There are several modified Taylorcrafts flying with more power and wing devices. Greg Clayton (the Taylorcraft skylight STC holder) has an experimental one here in Fairbanks with flaps and extendable inboard slats. I can take pictures if interested.

The question for me is would I be willing to duplicate the Helio's slat and flap design on the same airfoil? Is the Arctic Tern's flap design sufficient providing VG's or similar are added to control the stall behavior?

What it comes down to in my opinion is whether or not the Taylorcraft's airfoil is worth messing with beyond VG's? To me it's not as it takes too much to make it yield high lift and reasonable slow flight behavior. If I wanted STOL I'd get a plane with a Piper wing and modify as many have done to their satisfaction. My PA-12-180 had all the mods and room. I had two PA-18's and a PA-11 with flaps. And a Maule M-5 and a few Citabrias. A Taylorcraft is best as it is, and despite wishing otherwise, it's not a Piper when it comes to STOL. An neither is an Arctic Tern compared with a Super Cub from what I experienced.

Most of my flight time is in a C-185 which 2412 airfoil does what it does because of Cessna's flap system and various leading edge cuffs.

Please take this friendly opinion and good luck with your project.

Gary

[Nefj40]

Re: Flaps....again

Nothing wrong with opinions, sometimes things are brought up that a person hadn't thought of. On to the cuff. The reason I'm going that direction is because of exactly what Mackey claims. He says a Tcraft wing with a cuff makes it perform just like a cub wing, only with no speed penalty.

[PA1195]

Re: Flaps....again

I look at this as a long range discussion the distance of which exceeds the speed of sound. That's the Internet and Forums for you so let's try to make it work.

Auster with their MA-4 experimented with a cuff. It's described and available here. I have a copy from years ago: http://papers.sae.org/670245/

Cirrus and ICON A-5 aircraft among others employ a partial span LE cuff to tame the stall/spin behavior. Look at their websites for examples. It's well described in the literature.

On a C-185 I flew an early install of the Sportsman LE cuff now available from Stene Aviation. A sorta' report of my before and after experience from a phone interview: https://www.steneaviation.com/pages/...ska-circa-1989

I had a Crosswinds cuff installed on my 7GCBC and it helped STOL performance: http://crosswindsstol.com/index.html It's similar to the cuff I linked above described ion the SAE Paper by Cornish.

So yes Mackey is right in that a cuff can help reduce the pressure peak and bad stall behavior experienced near the wing leading edge at high AOA. It can offer a modest speed penalty providing the cuff doesn't extend excessively below the bottom of the airfoil.

The 23012 airfoil experiences a pressure peak and lift discontinuity at AOA > about 12*. Read here: https://books.google.com/books?id=Xt...20edge&f=false

That can be tamed some with VG's in my experience, and I assume with a LE cuff per the SAE Paper and Mackey's experience.

Gary

[PA1195]

Re: Flaps....again

Then there's these for certified Cubs and Experimental applications...the latest in STOL flaps that could be adapted to a metal spar wing. Similar to a DHC-3 Otter's flaps:

http://www.airframesalaska.com/PerformanceSTOL_a/268.htm

http://www.performancestol.com

http://www.airframesalaska.com/v/vspfiles/pdf/Performance%20STOL%20Order%20Form%20-%20Experimental.pdf

Gary

[PA1195]

Re: Flaps....again

If you're thinking cuff note this plot of the Taylorcraft 23012 airfoil in red over the Cessna 2412 airfoil in green. Note the similarity of the leading edge. They're close but not exact. The point being a cuff that works on the 2412 might be adaptable to the 23012. Just a thought.

The airfoil performance data can be generated here vs Reynolds Number as well: http://airfoiltools.com/compare/index and http://airfoiltools.com/calculator/reynoldsnumber

Edit: For comparison added Cub's USA 35-B and Taylorcraft's 23012 comparison. Easy to see the difference.

Gary

[Nefj40]

Re: Flaps....again

Some good info there. Those Keller flaps are nice, but ouch..$$$$

[PA1195]

Re: Flaps....again

Dave a couple questions please...what do you have for wing parts now? Have you installed VG's and flown them on your other Taylorcraft?

If you have flaps intact you could reconfigure the rear wing flap cove to allow better flow over the extended flaps. Lower gap seals don't work except for rate of climb and maybe cruise, but the shape of the upper flap seal is critical when the flaps are deflected.

Yes the keller units are expensive and require some custom fitting.

Some folks claim flaps don't work much to add lift. Ok, then only the raised aileron makes the plane turn? Stall speed is only an indirect indicator of flap effectiveness. The lift is there for takeoff and so is the drag and lower deck angle for landing.

Gary

[Nefj40]

Re: Flaps....again

I don't have any wings yet. I looked at a set last wed. and spoke with Scott from D&E a couple weeks ago. What ever I decide to do will kind of help dictate what set I'm going with. Yes, I put VG's on my current flyer a couple years ago. The new one will have them, and after putting them on my old plane, I kind of think that they are a mandatory item. That Fatzinger Taylorcub for sale on the SC.org has a Tcraft wing with flaps. I've personally spoke with a couple guys that are very familiar with it, and they say it performs great and is way faster than a standard cub.

[PA1195]

Re: Flaps....again

I didn't realize D&E were still around. They had great parts and Riblett ribs years ago...I assume it's the same company.

Edit: I see they're still at it: https://www.de-aircraft.com/aircraft...-for-sale.html and https://www.de-aircraft.com/customers.html

Any wings means you're without so that leaves it wide open for options. Probably easier to source what will fit the fuselage without lots of modifying.

I guess it's hard to have both speed and STOL. The T wing is fast but for carrying a load and STOL it needs mods to add lift and reduce the stall break. VG's help but...

If it were me I'd pick two...STOL, fast, easy, cheap,and go from there. I'd put a Cub or similar wing on for my Alaska flying especially on floats as speed is inconsequential versus load carrying and fuel range.

Gary