The 'daydreamers' thread...post your craziest designs and concepts here

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rotax618

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Yes, a high CL at 1.27 AR. But it comes with high Cd. Not a concern to Zimmerman because he was designing for powered vertical lift.
We are concerned with Cd and the resulting L/D, from the combined CL and Cd.
David Rowe reported that his UFO (AR 1.27, 12foot span) has an engine out glide similar to a Drifter, the UFO is an extreme Low Aspect Ratio aircraft. Please look at the video evidence before generalisation.
 

rotax618

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I have studied Zimmerman’s work and agree that lower A.R. generally has a lower L/D. There is an aberration at very low A.R., He didn’t study the effect of planform, his original experiment was with a rectangular wing with semi-circular wingtips and Clark Y airfoil. He measured the L/D as he reduced the span, when only the tips remained (a circle) the L/D Curve increased unexpectedly and the C.L. max continued to increase well past the normal stall break. Obviously as the C.L. increased so did the C.D.
The UFO and Arup types are able to fly pretty well in spite of their very low A.R. because they have a very low wing loading and because of the aberration measured by Zimmerman at angles of attack necessary for cruise the L/D is similar to that of a more conventional planform. With an LAR you can use that high alpha C.D. for very short landings.
There are no free lunches aircraft are designed for a mission there is no ideal aspect ratio and if your aim is to build a light, compact, safe single seat STOL sport plane don’t overlook LAR.
 

BBerson

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It isn't overlooking low aspect ratio if someone can design an AR-3 aircraft that climbs steeper than an AR-1.
Landing short is useless if you can't takeoff again from that confined area.
 

Himat

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It isn't overlooking low aspect ratio if someone can design an AR-3 aircraft that climbs steeper than an AR-1.
Landing short is useless if you can't takeoff again from that confined area.
Just remember, with fixed span the higher the aspect ratio the wing have the worse the climb.;)
 

pictsidhe

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LAR tends to have a better span efficiency than more conventional AR. But you will still increase induced drag as you lower AR. It just isn't quite as bad as you'd expect with constant e.
 

Himat

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Usually when discussing wing aspect ratio, the wing area is held constant. The result is that different span loadings are compared at a fixed area loading. Keeping the wing span constant, different wing loadings are compared at fixed span loading.

What physical size is varied with aspect ratio and what physical size is held constant when comparing different wing aspect ratios make a difference. Aspect ratio is dimensionless, but a change in aspect ratio changes either wing loading or span loading.
 

pictsidhe

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Usually when discussing wing aspect ratio, the wing area is held constant. The result is that different span loadings are compared at a fixed area loading. Keeping the wing span constant, different wing loadings are compared at fixed span loading.

What physical size is varied with aspect ratio and what physical size is held constant when comparing different wing aspect ratios make a difference. Aspect ratio is dimensionless, but a change in aspect ratio changes either wing loading or span loading.
But the dominant factors for climb rate are span and power loading. Wing loading is a far smaller effect.
 

rotax618

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What you say is theoretically correct, but please look at the video evidence of the LAR types, the UFO can takeoff and land in an extremely short distance, and from the videos so did the Arups, both types have a very good climb considering their low power. Scientific method suggests that if the theory doesn’t fit the evidence then you don't change or ignore the evidence, you amend the theory.
 

Himat

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But the dominant factors for climb rate are span and power loading. Wing loading is a far smaller effect.
Is it? Or is it speed?
Climb ratio do depend on span loading, power loading and wing loading. I would add that climb ratio depend on speed too. Of two airplanes with the same best climb L/D, the fastest airplane will have the best climb ratio in height gained by time.

Actually, I forgot that in the last posting. Comparing wing aspect ratios it is common to do it at the same speed. Now, if you rearrange the formula for how cl/cd depend on wing aspect ratio to be compared at constant span (and speed) you will see how cl/cd worsen with larger aspect ratios and higher wing loading.
 

Speedboat100

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I just dreamed that you shoot an airliner above the clouds with a rocket and assisted sling ( or a catapult )...and then spread the wings there...and start using ducted fans that run with solar power and batteries.
 

Tiger Tim

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Less of a daydream, more of a nightmare: the other night I had a dream I was going through a book on airplanes and within it was a few pictures of a replica “Jenny.” It was built full scale but powered by some air cooled horizontal engine and had the Super Cub-style pressure cowl to prove it. The wheels were chrome spoked motorcycle wheels with knobby dirt bike tires for good measure. Then, for whatever reason, from the trailing edge of the wing aft the fuselage and tail was scaled-down B-17 but of course fabric covered. It sure was something and even in my sleep it was a real WTF moment.

Having said that, I’d fly it every day if I had the chance...
 

lr27

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Make it out of wood...call it the ChubBee...The wife wouldn't come near it! LOVE the concept though. I'm starting two Giant lazy bee's right now for a winter build.
Go to Hip Pocket Aeronautics and check out the Chub. While you're at it, look at the Bostang and the Boston Speedster. All toon designs. Models, of course, but is you enlarged them.....
 

pictsidhe

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What you say is theoretically correct, but please look at the video evidence of the LAR types, the UFO can takeoff and land in an extremely short distance, and from the videos so did the Arups, both types have a very good climb considering their low power. Scientific method suggests that if the theory doesn’t fit the evidence then you don't change or ignore the evidence, you amend the theory.
And what is the power loading of those low AR designs? If your span loading is bad, you can up the power loading and still get great climb. Up the power loading enough, you don't even need wings.

Show me the numbers, I'll crunch them ands see if they fit current theory. I seriously doubt that they won't, or somebody else would have noticed and investigated in the decades since the Arups flew.
 

Hephaestus

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Go to Hip Pocket Aeronautics and check out the Chub. While you're at it, look at the Bostang and the Boston Speedster. All toon designs. Models, of course, but is you enlarged them.....
Not a fan personally.

d6647222165927.5630db76c3125.jpg

But if someone did the cartoon mustang... :wonder:

Or we talked cluttonfred into going f18 on his pusher
880b42a0f4ac01af6817024eaa829a72.jpg
:bow:
 

rotax618

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The Arups were built with different powerplants, try the UFO, 12ft span 50hp rotax 503, see if your theoretical performance matches the video evidence.
 

rotax618

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The documented performance of the Arup S2 -
“S-2 was 900+ lbs, on 37 hp engine got 97mph, and landed at 23mph. Silly slow approaches and short rolls.”
The S2 had a steep parachute like glide, but as you can witness from the old films, had a more than acceptable rate of climb considering its power to weight.
General characteristics

  • Length: 17 ft (5.2 m)
  • Wingspan: 19 ft (5.8 m)
  • Wing area: 211 sq ft (19.6 m2)
  • Airfoil: NACA M6
  • Empty weight: 780 lb (354 kg)
  • Powerplant: 1 × Continental A-40 , 36 hp (27 kW)
Performance

  • Maximum speed: 84 kn (97 mph, 156 km/h)
  • Stall speed: 20 kn (23 mph, 37 km/h)
  • Maximum glide ratio: 3 to 1 (citation needed)
 
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