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Wing Extensions
Seems like it might be useful to have removable wing extensions for an
experimental. There are times when you want a fast airplane for cross country and you can stand a long runway for the high TO/landing speeds and then there are other times you want the low speed handling for short field, etc. Flaps do this to some degree depending on how exotic you want to get and have the advantage of being adjustable in flight but the wing extensions would appear to extend the flight envelope (on separate flights) beyond what can be done with typical flap configurations. A solid composite structure, perhaps 2 feet on each side that plugs into the main spar(s) would do nicely to allow you to have both a high speed clipped wing plane (when removed) and a long wing high lift plane, of course not at the same time. The further out you go on the wing the less the loads are so these wouldn't have to be built up as strong as other parts. They could be made with no control surfaces or other moving parts. You could even select a different airfoil for that section if you wanted. No problem plugging composite extensions into an aluminum main wing. Of course the main short wing would have to be built to allow access to the main spar(s). A hollow rectangular cross section spar could accept an insert to mate with removable extensions. I guess you'd need some sort of plastic overlay for the airspeed indicator to remind you of the new critial speeds. Anyone seen anything like this? |
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Anyone seen anything like this?
A kitplane under design has a cruise and loiter wing. Go to www.vulcanaero.com/index.html to see it. Best Regards |
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"Jay" wrote in message m... Seems like it might be useful to have removable wing extensions for an experimental. There are times when you want a fast airplane for cross country and you can stand a long runway for the high TO/landing speeds and then there are other times you want the low speed handling for short field, etc. Flaps do this to some degree depending on how exotic you want to get and have the advantage of being adjustable in flight but the wing extensions would appear to extend the flight envelope (on separate flights) beyond what can be done with typical flap configurations. A solid composite structure, perhaps 2 feet on each side that plugs into the main spar(s) would do nicely to allow you to have both a high speed clipped wing plane (when removed) and a long wing high lift plane, of course not at the same time. The further out you go on the wing the less the loads are so these wouldn't have to be built up as strong as other parts. They could be made with no control surfaces or other moving parts. You could even select a different airfoil for that section if you wanted. No problem plugging composite extensions into an aluminum main wing. Of course the main short wing would have to be built to allow access to the main spar(s). A hollow rectangular cross section spar could accept an insert to mate with removable extensions. I guess you'd need some sort of plastic overlay for the airspeed indicator to remind you of the new critial speeds. Anyone seen anything like this? Glasairs have optional wingtip extensions. They add about 5 ft to the wingspan of the airplane. http://www.newglasair.com/glasairSIIspecs.html Rick Pellicciotti |
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Rick Pellicciotti wrote:
Glasairs have optional wingtip extensions. They add about 5 ft to the wingspan of the airplane. http://www.newglasair.com/glasairSIIspecs.html Rick Pellicciotti Granted that this would have been taken into account by the designer, but wouldn't this play hell with the center of lift and by extension throw off the CG? That is, it wouldn't modify the CG, just change where it SHOULD be. I'm thinking that it isn't a good idea in just any old plane. -- ----Because I can---- http://www.ernest.isa-geek.org/ ------------------------ |
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Chopping the wing will effect the center of lift for swept wing
aircraft, but most homebuilts (e.g RV) have a wing that just goes straight out, chopping wing just chops lift (and drag). And I'd have to agree, it ain't a good idea on just any old plane. First of all, you make the basic wing on the short side for your highest speed operation, then you have to expose the load bearing elements of the wing structure for your extensions to be able to couple. The structure must be able to handle the extra load from whatever longer wing extension you attach. But in the end, you have a plane with a wide operating envelope. The idea dawned on me after looking at the regular structure of an RV-8A wing I was watching being built up and comparing an aquintances shaved wing EZ that he says he needs to come over the fence at 100kts minimum but it goes real fast on a small HP motor. Ernest Christley wrote in message Granted that this would have been taken into account by the designer, but wouldn't this play hell with the center of lift and by extension throw off the CG? That is, it wouldn't modify the CG, just change where it SHOULD be. I'm thinking that it isn't a good idea in just any old plane. |
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On 18 Jul 2003 11:39:27 -0700, (Jay) wrote:
Seems like it might be useful to have removable wing extensions for an experimental. There are times when you want a fast airplane for cross country and you can stand a long runway for the high TO/landing speeds and then there are other times you want the low speed handling for short field, etc. Flaps do this to some degree depending on how exotic you want to get and have the advantage of being adjustable in flight but the wing extensions would appear to extend the flight envelope (on separate flights) beyond what can be done with typical flap configurations. A solid composite structure, perhaps 2 feet on each side that plugs into the main spar(s) would do nicely to allow you to have both a high speed clipped wing plane (when removed) and a long wing high lift plane, of course not at the same time. The further out you go on the wing the less the loads are so these wouldn't have to be built up as strong as other parts. You are describing the Glasair II, Super II, and Glasair III wings. There is a set of 2 foot extensions available from the factory, and others of different lengths from other sources. Down low the short wing loading in nigh onto 30# per square foot.. With tip extensions it's just a tad of 27# ft^2 The aspect ratio is 6.67 and 7.64 with the factory extensions. They could be made with no control surfaces or other moving parts. You could even select a different airfoil for that section if you wanted. No problem plugging composite extensions into an aluminum main wing. Of course the main short wing would have to be built to allow access to the main spar(s). A hollow rectangular cross section spar could accept an insert to mate with removable extensions. I guess you'd need some sort of plastic overlay for the airspeed indicator to remind you of the new critial speeds. They don't change all that much. You leave them set for the shorter wing. There are no real critical speeds...at least in the G-III. Vne is listed at 335. They are routinely flown at 350 (mph) doing aerobatics. Maneuvering speed, (Va) is listed at 201. I've flown aerobatics at Vne. Vno is listed at 280 while 75% gives a POH figure of 282. I've done letdowns at Vne. and have absolutely no worry about flying that fast. The wing tips will hold 5 1/2 gallons each, main tanks 53, and the header 8...unless you have brake cylinders on the right and that probably drops it to about 5. Many have additional wing bays turned into tanks as well. The Glasair (New Glasair) company recommends using the extensions until the pilot is thoroughly familiar with the plane and during the early phases of the flight test program. With a turbo at high altitude you are looking at a cruise that is well in excess of the book figure for Vne, The plane is way over engineered. Book figures are +6, -4 Gs, but again the plane has been tested wayyyy beyond that. Roger Halstead (K8RI EN73 & ARRL Life Member) www.rogerhalstead.com N833R World's oldest Debonair? (S# CD-2) Anyone seen anything like this? |
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