wing-x stol

[emwhiteman]

Hi all, i've been reading about the Peterson planes for the past year. I agree that the 260se is an incredible aircraft. Todd gave me a demo in the Katmai 300, i was even more impressed with its slow speed performance. Quite a machine! The Petersons were very helpful, it was a pleasure meeting with them.

I've read about the disadvantages of the traditional "leading edge cuff" stol kits. They rely heavily on increased maximum angle of attack for slower flight, thus you are "hanging on the prop", creating a less controllable aircraft at the slow end of the envelope. Obviously, wind shear or power loss could a more dangerous situation while in this high aoa. The Wing-x Stol wing extensions increase the wing area and aspect ratio, and would allow slow flight without this exagerated aoa when installed on a "non-canard" 182.

Some questions i have:

Could the performance of a 265hp(pponk o470), "Wing-x stol", "non-canard" 182 approach the slow flight performance, controllability, TO and landing distances of a standard 260se?

Does anyone know the tas stall speed of a "Wing-x" equipped "non-canard" 182? How would the slow flight angle of attack compare to the 260se aoa?

Finally, the 260se is said to stall, full gross, at 35 kias, and the katmai at 31 kias. Any idea what these numbers are when calibrated to true air speed? Cessna figures say the standard 182 stalls power-off @ 49 cas (obviously it would show a lower ias). Are the above 260se/Katmai speed numbers power-off stalls?

Many thanks,

Eric Whiteman

[jjbely]

Eric,

I think you are getting confused by with your airspeed between TAS , CAS and IAS.

If I remember correctly IAS is the speed read by the pitot static system. So a comparison between dynamic pressure and static.

CAS is calibrated IAS for instrument error, a small variation , I think.

TAS is CAs corrected for density altitude IE altitude and temperature.

For stall calculation, the one that matters is IAS or CAS but both are very close, specially at that low speed maybe a knot or two max.

From my single flying experience in a 260 SE with Todd, I think the canard on the 260 SE makes thge main difference from a normal A/C. Not only it generates extra lift , the position of this extra aerofoil so far ahead totally change the attitude of the aircraft at low speed. It's much flatter so the AOA is therefore much less at any given speed than a normal C182 even one with wings extension I presume. I would think that anything that let you fly at a lower angle of attack at the same speed is an improvement in safety if you want to fly low and slow.

Hope the above make sense ..

Cheers,

JJ

[emwhiteman]

JJ, thanks for your reply.

I think you're right-on with your air speed definition, but the difference between CAS and IAS is pretty big at stall speed. What I am trying see is an accurate comparison of stall speeds for these different planes (stock 182, 182 with Wing-x, and 260se). The comparison of a stock 182 stalling at 49 KCAS and a 260se stalling at 35 KIAS, seems like an unfair comparison, apples to oranges. On the 172 I presently fly, the calibration table shows 40 KIAS = 49 KCAS @ full flaps and 40 KIAS = a whopping 53 KIAS with no flaps. Quite a difference between CAS and IAS at stall.

I believe the reason is that the higher AOA (which is its highest at stall) causes the larger discrepency between CAS and IAS (less direct air into pitot tube). Does anyone know the CAS stall speeds for the Wing-x 182 and the 260se, so I can accurately compare the stall speeds?

From the research I've done thus far, I think that for a given slow airspeed, that the 182 with canard would definitely fly flatter than a "wing cuff style STOL" 182, but i bet the AOA on a Wing-x 182 would be closer to a 260se. I just don't know how close? Anyone have Wing-x experience on a non-canard 182? Wing-xers feel free to chime in!

I believe the Wing-x creates more lift by using more wing. So for a given airspeed the Wing-x should allow a smaller AOA when compared to a stock 182. I compare that method of STOL to how I believe a traditional "wing cuff STOL" works: for a given low airspeed a wing cuff, allows the wing keep flying at higher AOA than possible with a stock 182.

FYI I'm trying to figure out how I will outfit my 182, when I'm able to find the right one! :)

[Todd Peterson]

The nose mounted canard provides the flat attitude at slow speed. This in turn results in better stall resistance, improved aileron control, better over the nose visibility, improved go around capability, nose wheel protection in rough terrain and improved pitch authority. It is a lifting surface and the lift provided by the canard removes an equal amount of aerodynamic down load (dead weight supported by the wings) off the tail. None of these characteristics can be attributed to the longer wing as the 260SE has been flying this way with the standard wing for twenty years. It has been my experience the longer wing will lower the stall speed about four or five knots. The lower stall speed is essentially the biggest benefit the longer wing provides. The canard and the long wing work well together for those wanting maximum short field performance or safety.

The longer wing on a stock C182 will also lower the stall speed in a similiar manner. The aerodynamics of the airplane remain the same however. You still have a high angle of attack at slow speed, it's just four knots slower. This means you still operate close to the stalling angle of attack, the maneuverability is the same as a stock C182 as is everything else. It's just four knots slower. One of the fundamental problems associated with a stock C182 is inadequate elevator authority at slow approach speeds. This results in the nose gear being damaged on a lot of C182's during the flare on very slow landings. Needless to say being able to land four kts slower will not help that problem much. Fortunately the canard provides twice the pitch control so the additional pitch authority provided by canard elevator eleminates the problem even with the longer wing. The longer wing alone will provide more safety when the airplane is flown at normal approach speeds. If one wants to hang on the prop and get behind the power curve then you could come in four knots slower. But now we are getting back to a lack of elevator authority in the flare and being on the back side of the power curve and their associated problems. The longer wing allows the earlier C182 models an increase in the gross weight which is also good. The airplanes we work with already have the higher gross so that does not affect us.

The accuracy of indicated airspeed is dependent on the angle of attack. Conventional aircraft use progressively higher angles of attack as they get slower where our aircraft stay relatively flat. The airspeed indicator on a stock C182 is reasonably accurate at cruise. It is equally accurate if the airplane is flying in the same flight attitude at 55 kts. The speed really matters little, it is the flight attitude that counts. The difference in indicated speeds can readily be seen by looking out the window. It is also substantiated by the extremely short landing distances our airplanes are capable of. Slower speeds just result in shorter roll outs.

The canard can be used with any engine as long as the orginal engine mount is retained. There have been some vibration issues with the 520's and 550's and this will show up in added maintenance of the canard, engine baffeling, exhaust system and airframe in general. The extra weight of these engines will hurt the airplanes slow flight characteristics unless a counterweight has been added to the rear of the fuselage. This is one of the reasons we use a two blade propeller rather than a three blade propeller. The extra weight of the three blade prop really messed up the slow flight handling characteristics. The only reason the I0-550 powered King Katmai flies so well is that we offset the additional weight up front with a counterweight in the tail. The slower approach speed of a stock (non canard equipped) C182 provided by the longer wing when combined with the extra weight of a bigger engine would be the worst of all worlds when landing. A nose heavy airplane with a limited elevator. The fuel injected engine will also provide more power than its counterpart with a carb. This is due to the ability of the fuel injected engine to pull more manifold pressure. It has been my experience that a fuel injected engine will pull about two more inches MP than one with a carb. If you pull the throttle back two inches that is a big power loss. The fuel injected engine will also operate LOP which provides a large savings in fuel. An engine with a carb does not have the ability to run LOP and one still has the problem of carb ice to contend with. The last AOPA Safety Report I read on the C182 showed nose wheel damage and carb ice as the leading safety issues. Both of these are eleminated in the 260SE and Katmai.

Boy I didn't realize how long this had got. I better sign off.....and go do some flying. CLEAR!!!!!!!!!!!!!!!!!!!!!!!!!!!