Why no flaps?

[Battson]

Further to my last post, I found this comparison on kitplanes:

http://www.kitplanes.com/issues/29_3...n_20375-1.html



Maybe I should be posting in the Patrol section...

[Jflyer]

I couldn't state what empirical evidence this is or is not available. The conversation was about some Alaska CUB pilots not believing the Patrol has similar STOL capabilities yet it can fly 40MPH faster than the cub. My point is that a large part of this, is a superior wing on the Patrol.

[Razncain]

John, thanks for the time you put in your post, good stuff. I went looking for Ribblett’s book you recommended at Amazon, and unfortunately it is out of print. I’ll keep an eye out for it elsewhere, sometimes booksellers at e-bay sell out of print books.

Battson, SuperCubs are great planes, would be proud to own either one, but engines being equal, seems like the Patrol has considerably better cruise speeds. Definitely got to love Mackey’s SQ2, amazing what he can do with his plane. Probably my favorite video of STOL aircraft. If the prices of their kits ever come down to earth, they would get another look from me, but I’m sure that isn’t going to happen. http://www.youtube.com/watch?v=ct2fNFc8AxY

[Battson]

The man I bought my 26' tires from owns an SQ-2, sure looks like a lot of fun!!

[mswain]

EAA sells the Ribblett book, I purchased mine from them last year: http://www.eaa.org/en/eaa-shop/media...0__ga-airfoils

[Razncain]

EAA sells the Ribblett book, I purchased mine from them last year: http://www.eaa.org/en/eaa-shop/media...0__ga-airfoils

That was quick! Ask and ye shall receive. Thanks!

[Jflyer]

I downloaded a copy of the book from www.scribd.com. I paid the $8 for month's subscription and downloaded this book plus all the referenced material in Harry's book that I could find there. A wealth of information.

[aeronca7ccm]

Has anyone considered Gurney flaps (wickerbills) on the LSA?

[Wayne Massey]

Personally I wouldn’t change anything on LSA as it is designed. The LSA doesn’t need flaps. Flaps add weight, complexity and build time. Bob flew his LSA at the Oshkosh STOL competition competing with airplanes build just for that. Take off roll in the LSA was 90 feet and landing was 140 feet. I doubt flaps would improve those numbers by much. Last month Bob was flying around the NE in his LSA with the Ohio Bush Pilots. The LSA out flew the super cubs with better STOL performance and he had to power back (slow down) so they could keep up with him flying cross country. I like the "keep it simple" concept of the LSA as is.

[1planeguy]

Know this is a fairly old thread but wanted to throw out another thought on the "Superiority" of the LSA/Patrol to the SuperCub. A few folks were comparing the performance difference to just the differences between the airfoils. My suspicion is the choices Bob made with the wing CONSTRUCTION goes alot more to accounting for the improvement in cruise speed (or lower power required for a given cruise speed). His choice of an aluminum wing that could handle torsion loads without needing an aft strut...a rigid enough lift strut that didn't require jury struts..keeping the aileron controls IN the wing instead of hanging in the breeze ala Supercub...the aileron hinges not hanging under the wing...etc. etc. All of this added up to greatly reduced parasitic drag. While the nice Riblett airfoil should get some credit for a reduction in induced drag...parasitic drag was the MAJOR improvement by Bob.

Way back in the 70's Jim Bede wrote a series of articles on design for Sport Aviation magazine that had great info on the benefits of removing parasitic drag. Bob has incorporated about 75% of the things Bede mentioned (the next ones would be making the tailplane cantilevered to remove the brace wires (weight penalty) and the big one...fully cantilevered wing (MAJOR weight and complexity penalty)). So really Bob has hit the sweet spot between aerodynamic cleanup vs. build complexity vs. weight increase for the aero improvement.

On the STOL side of the equation, some of the hardcore STOL crowd will say there is no such thing as too much drag when you are trying to slow down for a short runway...to which I personally think "horse feathers"...if you are building your own plane, "controllable" drag can always be had in the form of flaps or spoilers...and removed when you are trying to climb. The "like lots of drag" crowd seems to forget that on climbout the extra thrust required to overcome that "permanent" drag, could be put to use as extra climb rate to clear that big tree on the end of the runway if it wasn't a permanent fixture of the plane.

My $.02 worth and worth what ya paid for it.

[N942VT]

I flew Mark's LSA today here at Sebring with Wayne in the front seat, very impressive take off and climb. I noticed the tail come up real quick and a very short roll before a steep climb out. I asked Wayne to come in high and slip hard which he did and the plane came down real fast. These are all seat of the pants observations as I really couldn't see the panel well but it flew as I expected. Sportier than my Bearhawk but very familiar. This plane slips well, very steep angle and slow approach. I see where Bob is coming from better now.

[Mark Goldberg]

Just a quick comment to the poster before Dave Lenart. You are correct about all the fuselage drag/hinges etc creating drag. But according to Bob, most of the extra cruise speed of the LSA and for that matter the Patrolis due to the aluminum flush riveted wing and better airfoil. He told me that all the things you mention also contribute to the fsster speeds. But the majority of the improvement is from the wing. Mark

[N942VT]

Thanks again Mark for the ride, you were out when I came by the booth. Hope to show up again tomorrow.

[N942VT]

Some interior shots of Marks LSA

[Phil]

Know this is a fairly old thread but wanted to throw out another thought on the "Superiority" of the LSA/Patrol to the SuperCub. A few folks were comparing the performance difference to just the differences between the airfoils. My suspicion is the choices Bob made with the wing CONSTRUCTION goes alot more to accounting for the improvement in cruise speed (or lower power required for a given cruise speed). His choice of an aluminum wing that could handle torsion loads without needing an aft strut...a rigid enough lift strut that didn't require jury struts..keeping the aileron controls IN the wing instead of hanging in the breeze ala Supercub...the aileron hinges not hanging under the wing...etc. etc. All of this added up to greatly reduced parasitic drag. While the nice Riblett airfoil should get some credit for a reduction in induced drag...parasitic drag was the MAJOR improvement by Bob.

Way back in the 70's Jim Bede wrote a series of articles on design for Sport Aviation magazine that had great info on the benefits of removing parasitic drag. Bob has incorporated about 75% of the things Bede mentioned (the next ones would be making the tailplane cantilevered to remove the brace wires (weight penalty) and the big one...fully cantilevered wing (MAJOR weight and complexity penalty)). So really Bob has hit the sweet spot between aerodynamic cleanup vs. build complexity vs. weight increase for the aero improvement.

On the STOL side of the equation, some of the hardcore STOL crowd will say there is no such thing as too much drag when you are trying to slow down for a short runway...to which I personally think "horse feathers"...if you are building your own plane, "controllable" drag can always be had in the form of flaps or spoilers...and removed when you are trying to climb. The "like lots of drag" crowd seems to forget that on climbout the extra thrust required to overcome that "permanent" drag, could be put to use as extra climb rate to clear that big tree on the end of the runway if it wasn't a permanent fixture of the plane.

My $.02 worth and worth what ya paid for it.

You hit the nail on the head. Living in Alaska, the first question everyone asks me is how the Patrol compares to a Super Cub. I usually point out that it's the same weight as a Cub, Same wing area, thicker airfoil, twice the flap area (9' x 20" flaps vs. 5' x 12" flaps on a cub) and same or greater power than a cub. Why wouldn't it take off and land just as short? Then I point out all the parasitic drag that's missing on the Patrol. Hanging out with Mark and AK_Patrol at the Alaska Airman's Show last year I had this conversation a lot. And having a cub parked 50' away just made it that obvious.

[John Massaro]

All,

Regarding flaps, take a look at this video and watch Barrows go into what looks to be a textbook forward slip on approach to land-

https://www.youtube.com/watch?v=ScLA1AA_5kA&feature=youtu.be