Smallest possible ultralight for real men 230lbs

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topspeed100

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Topspeed - try a pusher and get to see where you are going ;) Having the engine 'in your face' as shown would be dreadful for forward vision and noise etc (no chance for a good muffler etc and too small prop ) Something along the lines of a scaled down Transavia Airtruk could be a good compromise between a tailess and a twin boom design perhaps. Your Finnish 'design DNA' should be able to work up something attractive ..
Right this is very attractive ? 800px-Airtruk.jpg
 

Xanadrone

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Classic simplicity leading to lightweight is indeed attractive, but I really doubt that the Hippiainen would even take off from ANY airfield (NASA Langley included) on a hot day with only 4.5 HP, topspeed100... not talking about ANY climb rate with a weight/power ratio of approx. 40 kgs/HP.:speechles

I guess (maybe too... minimalistic myself) that a 2 x 4.7 HP push/puller micro...motorglider (powered by let's say 2 X 57 cc Saito 4t-RC boxer engines) would be on the verge of the absolute minimum power-request for this type of aircraft.

Not to be misunderstood, though - so go on please with your pursue of extreme minimalism (I really like the originality-tidbits included in some of your ideas), but try not to forget the harsh reality of the laws of physics and formulas containing some "not-so-much-minimalisable" numbers...
 

WonderousMountain

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Yes, a little nose-heavy for aerobatics, depending on actual weight. The air tractor is a deceptively good plane. It lifts a lot of weight with very little power. A very good starting point for minimalist aircraft that have Empty Weight fractions less than 1/2 AUW.

Topspeed,

I don't know the performance of your airfoil, but a "back of the envelope calculation of 75ft/s takeoff speed exceeds 50mph. IF this actually were minimum power speed, the backside of the power curve would be anything slower. Max L/d would be over 100ft/sec, even at say 25 pounds total head resistance, and Very efficient propeller, you're looking at 5hp for flight, you will want probably double that for safety/climb. So I do agree with the previous post. At low speeds laminar flow will be ruined by turbulence, so you cannot use ideal drag figures. This is also such things as downdrafts, which can crash an ultralight very effectively, especially in canyons. Perhaps you could do push pull, giving one engine out capability, and more propeller disc area. Have you considered using single cylinders laid horizontal and geared? Probably not cheap to get fins machined vertical.

If you do go piston engine, the exhaust could be routed through supports so it doesn't get in your face, or add drag. Really surprised there's no wing taper, perhaps you are getting serious about managing construction difficulties. Or maybe a concession to Reynolds effect. The hoerner wingtip reduces induced drag significantly without reducing aileron effectiveness noticeably, are cost effective and light.

Does it give you the visibility you desire? Not being a pilot, cabin comfort isn't my specialty.
 

topspeed100

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Classic simplicity leading to lightweight is indeed attractive, but I really doubt that the Hippiainen would even take off from ANY airfield (NASA Langley included) on a hot day with only 4.5 HP, topspeed100... not talking about ANY climb rate with a weight/power ratio of approx. 40 kgs/HP.:speechles

I guess (maybe too... minimalistic myself) that a 2 x 4.7 HP push/puller micro...motorglider (powered by let's say 2 X 57 cc Saito 4t-RC boxer engines) would be on the verge of the absolute minimum power-request for this type of aircraft.

Not to be misunderstood, though - so go on please with your pursue of extreme minimalism (I really like the originality-tidbits included in some of your ideas), but try not to forget the harsh reality of the laws of physics and formulas containing some "not-so-much-minimalisable" numbers...
Right you are...I refer to 149 cc B&S that can be tuned for 10 hp.
 

Tiger Tim

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My straight gut feeling is that to make any use of minimal HP in a slow flying aircraft, that prop will need to be huge and turn at a very low RPM. To get prop clearance you can either mount the engine way higher or eliminate the weight and drag of all those struts by mounting the engine on the nose. Take a look at a Sky Pup for what has to be the very easiest way to stick an engine on an airplane.

Also, the main spar carry through seems ergonomically wrong, like you wouldn't be able to get in or out as it stands.

If you get it all sorted out it looks like it would be a fun little airplane.

-Tim
 

topspeed100

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My straight gut feeling is that to make any use of minimal HP in a slow flying aircraft, that prop will need to be huge and turn at a very low RPM. To get prop clearance you can either mount the engine way higher or eliminate the weight and drag of all those struts by mounting the engine on the nose. Take a look at a Sky Pup for what has to be the very easiest way to stick an engine on an airplane.

Also, the main spar carry through seems ergonomically wrong, like you wouldn't be able to get in or out as it stands.

If you get it all sorted out it looks like it would be a fun little airplane.

-Tim
You mean you cannot get in or out like in a normal sized plane. This has to be like this to be what it is. The prop is very efficient like it is since it is not washing the fuselage with the prop flow, but gets real trust. Prop arch dia is more than 700 mm..it is normal for 2 strokes and some 4 strokes with small engine in paragliders. Certainly it could be adjusted few centimeters higher.
 

Tiger Tim

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You mean you cannot get in or out like in a normal sized plane.
I mean unless I'm reading your three-view drawing wrong, the pilot will have to bend their knees backwards to just slide down into the cockpit. At least a "Real man of 230lbs" will.

The prop is very efficient like it is since it is not washing the fuselage with the prop flow, but gets real trust. Prop arch dia is more than 700 mm..it is normal for 2 strokes and some 4 strokes with small engine in paragliders. Certainly it could be adjusted few centimeters higher.
I guess I need to see an example of this working well on an airplane. I'm just picturing slow flying airplanes making better use of their power with long props.

-Tim
 

topspeed100

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I mean unless I'm reading your three-view drawing wrong, the pilot will have to bend their knees backwards to just slide down into the cockpit. At least a "Real man of 230lbs" will.


I guess I need to see an example of this working well on an airplane. I'm just picturing slow flying airplanes making better use of their power with long props.

-Tim
Tim ! That would really be unconvienient. I figured he slides the legs in while leaning butt on the rear fuselage former in cockpit and and holds on the engine pod and slides down his weight on the seat..seat may have to be set rear and adjusted forward when seated. A mock up might be good to prove this.
 

Tiger Tim

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That might be possible but as someone who is 6'5" (198cm) you'd be surprised at what airplanes I don't fit into!

-Tim
 

Tiger Tim

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I wonder if you could run the spar under the pilots knees the. Use some combination of dihedral and sweep back to put the centre of pressure back where it needs to be. If you did that and put the engine on the nose, everything from the firewall to the windscreen could open up for easy ingress and egress. Literally every person in the world could fit.

-Tim
 

Dana

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Has any one ever built an ultra light with a sealed wing structure capable of holding helium?
There wouldn't be enough helium to create a significant amount of lift.

Dana

Hardware: the part of the computer that can be kicked. If you can only curse at it, it's software.
 

Tiger Tim

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Well, I have a 36" inseam when I buy pants so whatever proportion of back to leg that works out to is what I am.

-Tim
 

topspeed100

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Little survey..If this meet the PART 103 and is 60 kg empty and flies with an inexpensive engine..would you buy one at 15 000 euros ( 20 000 usd ) ?
 
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