Time to consolidate some loose ends.
Those with a long memory may recall that I introduced myself on this forum thinking about this design, a tandem aluminum LSA:
A lot of time has passed, during which the mission, the primary material, and a lot of other things have changed. I've posted a few bits and pieces recently and received some requests to post more. I've always been hesitant about posting details but maybe the time has arrived for a real project log. Of course there have been a lot of iterations since that first sketch, but currently it looks something like this:
The mission: A light, relatively simple personal cruiser with performance above the LSA class, but not a crazy stall speed for a low-time pilot like me. The majority of flying will be local, but it should be efficient enough for some good cross-country distance. Good performance at hot/high DA is a must. Construction will be plywood; quick build time is not a priority. Must be roomy enough to fit my tall frame with wiggle room for a comfortable 3-4 hour leg. Needs to carry enough baggage for a civilized weekend or an "uncivilized" week of camping at OSH. No passengers to complicate things--that can wait for a future design. This one's a personal fun/travel machine.
Rough figures (of course subject to wild revisions, as they have undergone many iterations to date):
At OSH this summer, I showed a previous version of the design to someone, who said it reminded him of the Polen Special. BJC mentioned the same thing recently. The resemblance is coincidental, but I will confess that both the Polen Special and GP-5 are among my favorites and probably have subconsciously influenced the form, as well as all of the wonderful F1 racers at Reno. One thing that is a bit unconventional is that the spar passes just in front of the rudder pedals, rather than below the pilot's knees. There is a little weight penalty (and a visibility penalty) to be paid for this, but to my eye, it makes for a more elegant design.
Discussion thread here: https://www.homebuiltairplanes.com/forums/showthread.php?t=28827&p=410843#post410843
Those with a long memory may recall that I introduced myself on this forum thinking about this design, a tandem aluminum LSA:
A lot of time has passed, during which the mission, the primary material, and a lot of other things have changed. I've posted a few bits and pieces recently and received some requests to post more. I've always been hesitant about posting details but maybe the time has arrived for a real project log. Of course there have been a lot of iterations since that first sketch, but currently it looks something like this:
The mission: A light, relatively simple personal cruiser with performance above the LSA class, but not a crazy stall speed for a low-time pilot like me. The majority of flying will be local, but it should be efficient enough for some good cross-country distance. Good performance at hot/high DA is a must. Construction will be plywood; quick build time is not a priority. Must be roomy enough to fit my tall frame with wiggle room for a comfortable 3-4 hour leg. Needs to carry enough baggage for a civilized weekend or an "uncivilized" week of camping at OSH. No passengers to complicate things--that can wait for a future design. This one's a personal fun/travel machine.
Rough figures (of course subject to wild revisions, as they have undergone many iterations to date):
- Limit load: +6/-3
- W0 = 1,260 lb
- We = 806 lb (needs to be verified as I get a little further along with structural design--I hope I can beat this figure.)
- Wf = 203 lb
- Span = 25'-6" (A = 8.0; λ = 0.5)
- Wing area = 81 ft2
- Wing loading = 15.6 lb/ft2
- Stall speed (V0) = 58 mph (assumes overall flapped CLmax = 1.8; airfoil has not been finalized but assumes GA37A15 for now)
- Vcr = 149 kt IAS / 197 mph TAS @ 75% 7,500 MSL; 128 kt IAS / 147 mph TAS @ 55%, 7,500 MSL
- Range = 597 sm @ 75%, 7,500 MSL / 749 sm @ 55%, 7,500 MSL (no reserve)
- Power = 140 hp (turbocharged 2775cc Corvair; this figure may be optimistic but it will do as a placeholder for now)
- ROC = 1,320 fpm (SL); 1,000 fpm 7,500 standard day
At OSH this summer, I showed a previous version of the design to someone, who said it reminded him of the Polen Special. BJC mentioned the same thing recently. The resemblance is coincidental, but I will confess that both the Polen Special and GP-5 are among my favorites and probably have subconsciously influenced the form, as well as all of the wonderful F1 racers at Reno. One thing that is a bit unconventional is that the spar passes just in front of the rudder pedals, rather than below the pilot's knees. There is a little weight penalty (and a visibility penalty) to be paid for this, but to my eye, it makes for a more elegant design.
Discussion thread here: https://www.homebuiltairplanes.com/forums/showthread.php?t=28827&p=410843#post410843
