| Author | Message | ||
     Matthew Byrne New member Username: Mbyrne Post Number: 37 Registered: 07-2003 |
What can anybody tell me about the original wheeler wings with the flaps that were in reflex during cruise flight? Thanks, Matt | ||
| Al Kittleson New member Username: Al38kit Post Number: 23 Registered: 07-2007 |
It looks like this has not been a popular topic! I'm rebuilding this wing and could make the flap change at this time, but would also like to know if anyone has tried the reflex. Buhler? Anyone? Al Kittleson | ||
| Jim Ward New member Username: Jehward Post Number: 59 Registered: 02-2000 |
Al: I have not been flying long enough to know if the reflex makes any difference, however, my flaps do reflex on their own, up about 1/4" in flight. There must be enough "give" in the system to allow for this, since they rturn to zero upon landing. Let me know if you need any photos of the "picture frame" reinforcement for Rib R. I also took a tracing of the "picture frame" before I installed it, if Steve Furgesi can't help you. Jim | ||
| Al Kittleson New member Username: Al38kit Post Number: 24 Registered: 07-2007 |
Jim, I'm in the process of beefing up the rib with some 1/2" Oak plywood, flox, glass and probably an Al plate (to distribute the load), but a pic of the window assy would be appreciated. Regarding the flaps, I have had experience with other planes using reflex, and it often allow you to offset some elevator forces in cruise and pick up a few knots, also helps with CG changes sometimes. It would be interesting to find info from some long time flyers who use this. I think I saw somewhere in some old plans that 10 degrees was mentioned...a pic or two at alfranken@msn.com would be great. Thanks, Al... | ||
| Al Kittleson New member Username: Al38kit Post Number: 25 Registered: 07-2007 |
Hi Al My recollection is that the original flap system was designed to reflex about 5 deg. However flight observations indicated that the reflex made no appreciable difference so they just went ahead and designed the reflex into the structure - see flap setting template - so you already have it. Bill C | ||
| Matthew Byrne New member Username: Mbyrne Post Number: 47 Registered: 07-2003 |
"The -10 degree reflex is actually already built into the wing, so there's no special actuation necessary. What you perceive as 0 degrees/stowed flaps is actually the reflexed position. The airfoil used is a bastardized version of a NASA laminar flow airfoil, the NLF(1)-0215(F) section. NASA (and Dan Somers) designed it as a sailplane airfoil back in the 80's, and someone got the idea to use it for GA aircraft. To 'tweak' it to meet higher speed needs of kit aircraft, the aft 25% of the airfoil was reflexed (-)10 negative degrees. That then became the normal 0 degree setting on the Express and other designs that used it (such as the Lancair 200/300 series). In reality, when you deploy the flaps 10 degrees, you're actually back at the original airfoil shape. 40 degrees of deflection is actually 30 degrees from the base airfoil shape, and so on. Long story short, the reflex is already built in. The other 'tweak' that was incorporated was to flatten the bottom side of the reflexed section. The original shape had a notable cusp on the lower side, which lead to heavy ailerons at higher speeds. Flattening the bottom surface removed some of the aerodynamic resistance. The airfoil/wing used on your Express is the same as the original Express up through the Series 2000 model. When I departed EAC in 2001, Dick Scherrer and I were just finishing up the new airfoil and wing design for the RG model. The company later decided to incorporate it on the fixed gear model as well, but to my knowledge there are no other flying versions of it. Most kits manufactured up through the factory closing still had the old wing, other than the RG kits and *possibly* the last few FG buyers. Hopefully that answers your questions regarding the reflex and some history behind it. I'd be happy to share whatever information you seek, although I'm going to be in and out of town over the next week and a half (e-mail may be best until things relax in early July). Feel free to toss across any questions you have in the meantime." quoting a wheeler engineer... | ||
| Reinhard Metz New member Username: Reinhard_metz Post Number: 83 Registered: 03-2003 |
One more piece of lore to go with the above - Some have proposed that in flight a slight speed improvement may be achieved by extending the flaps about 2 or 3 degrees (i.e. decreasing the reflex to 7 or 8 degrees). I have tried this several times,and while there is a slight but noticeable pitch change, I have not experienced any associated speed increase. | ||
| Jerry Sjostrand New member Username: Jerry Post Number: 77 Registered: 08-1999 |
Thanks Reinhard. Same was true of N360EZ. Good luck AL. Jerry Sjostrand |