Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by cluttonfred, Jul 13, 2010.
How do you get to see any of this translated to english,henryk?
This guy was awesome, is there anything on how he calculated and carved his propellers? In English?
Dang those are nice props!
The Pterodacytl canard was....optional, also not usually weight bearing. Figure it as a flying wing, and the canard pure pitch control. You trimmed with weight shift, and the canard just floated in trail at cruise.
In another thread someone says weight shift pitch control restricts you in turbulence.... True. However the Pterodactyl is an example of how absolutes are wrong. Weight shift controlled 'dactyls had a decent safety record, you were limited in speed ( it's hard to pull forward to far in the cage. ) the canards gave you more authority, and it could be abused. ( Big engines and higher than manual speeds were a factor )
The Easy Riser? Do you figure span loading on each wing separately on a biplane? ? Experience shows they are very strong, fly well on marginal power. ( but marginal... is marginal. Trees rising before you........ )
A lot of Hawks ended up over weight, in part because "more power" and luxury items, like instruments. the later, lightened version did make weight, but with a small engine. It has a decent wing, and like all pt 103 craft, building light is an art and a necessity.
I'd think any of the above would fly well and climb great with 30 odd hp. ( which, unfortunately, is twice the desired figure. It's what I'm planning on for a trike, seeming to have the best power to weight balance with enough for good climb. ( Polini Thor 200 ) )
Flying on 14hp in cruise should be sufficient. But for takeoff, another engine booster is needed. Could be electric.
Easy to start electric when needed.
The further apart vertically the two wings are, the more span efficiency you get. So maybe the Easy Riser wings have the induced drag of a monoplane with a bit more span. However, biplanes are draggy. All that rigging and interference between the wings will have an effect, as will the flying wing issue.
-yes,it was circa 200 mm tube glued from 1mm birch (3-leyer ) from Canada...
-Alu fuselage, wooden wheels, all very ligt.
=He was started (take off) at half power...
=no foot pedals,only hand controll.
Josef was flown on his airplanes>1000 hours !!!
-last tragic fly in 1990, very good weather condytion,
at circa 50 m level left wing was broken (I was whitness !)
my English is to poore to translate...
I am sorry to hear that you were the unfortunate witness to your friends demise. Tragic.
I am very interested in his propeller designs, is there any information on the formulas he used or the methods he used for carving them?
Back to the Solar Challenger and its cantilever tubular spar.... In less extreme cases than the Solar Challenger, say a Part 103 ultralight or a European two-seat microlight, are there any advantages to the tube monospar vs. a straightforward D-cell like an Ercoupe?
I could see something like an 8" heavy wall PVC pipe with grooves cut in it for pulled rivet clearance used as mandrel to create a tubular aluminum spar with tapered wall thickness, a bit like an old-fashioned spyglass riveted in the extended position.
Jozef was a technician,not engineer,but with big knowlage in aerotechnic...
-propellers are selbst construction,but I have not this data.
I have only one exemplar from STRATUS,iff interesting,it is possible to made photos.
-Jozef was made maschine for mechanical copying woden propellers...
PS=Jozef Bozecki was dead when 60 year old,but doctor was thinking,he was 40-years !
I am looking closely at the Solar Challenger type cantilever tube spar.
Might go with octagonal aluminum sheet built up tube. Easier for me to bend up the eight sides than roll a round tube.
The Ercoupe isn't D-cell (skin is not fully to lower spar). It is diagonal rib braced for torsion.
Genuine question, not snarky: Is there any particular reason to go to all the complexity of a built-up tube spar, rather than a commercial, off-the-shelf tube? At that point, it's no more difficult to build an I-beam and D-tube than it is to build up the octagonal tube. If the reason for a tube spar is to make things easy and quick, why make them difficult and slow?
Maybe I'm confused, but it seems to me that diagonal ribs or bracing might be stiffer for the weight than a tube. Much more area is "enclosed". Of course there are many factors.
OTOH, if you compare a spiral wrapped carbon fiber tube with aluminum diagonal ribs, it might be a different story.
P.S. For very light, relatively low stress wings, there might be a wall thickness and buckling issue. In that case, the tube might be better.
Nothing available off the shelf. The Kolb used 6063 5" and 6" .052" irrigation tube which isn't that strong compared with 2024 or 7075. A built up tube could be optimised and tapered. Sure, more work. But shipping a 16 foot tube isn't trivial either. A built up tube could be assembled in 4 foot segments. So looking at all sides.
Diagonal ribs requires two spars. And weight behind main spar is more flutter prone. No easy answer.
I agree with the second two points but I am not sure about the first. Why would a wing with diagonal ribs need a second spar more than one with straight ribs? Wouldn't a D-cell or single large tubular spar also work?
Evidently "strong enough" for their uses, though. Can't argue with the shipping problem, however.
Diagonal ribs need two spars for drag/anti drag.
Sure, a single large tube can do beam and torsion in one major part. That was my reason for looking at a large tube, it does two things in one. The D-cell makes a nicer shaped airfoil leading edge, but that may not be of any use on an ultralight. Dana said a 5" tube spar with strut Kolb wing is a bit soft in torsion with aileron torque. 6" is better.
So a cantilever wing tube should probably be 7-10" deep for bending, I think.
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