Very low aspect ratio planes?

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Jimstix

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LAS CRUCES NM
Full disclosure – I love goofy, weird airplanes with bookshelfs to prove it. Low-aspect-ratio (LAR) wings just have no real place on non-goofy general aviation airplanes. Sure, there are structural advantages and “look what I built” pride of the builder. However, these are not compelling reasons to design a LAR light airplane.

Reasons you might want to have a LAR airplane include:

  • Launch into space and reentry into the atmosphere (lifting bodies and shuttle orbiter)
  • Fit into the bomb bay (XF-85) or on a MIR or TIR (JDAM kitted Mk 82’s)
  • Fly faster than the speed of sound (gobs of delta-winged jets)
  • You need improved body lift to maneuver (Standard Missile)
My guess is that you won’t be doing those things.

The opposite of LAR wings is HAR wings – like sailplanes and (wait for it) helicopters.

We all know that sailplanes are efficient (low induced and profile drag). What about helicopters? Long skinny, twisty, droopy HAR blades work much better than short, wide LAR blades having the same blade area. That’s because a key figure of merit in a helicopter rotor is disk area – not blade area. Helicopters barely fly with those HAR blades and will not work with the short, wide LAR blades.

I don’t wish to be a Debbie Downer on LAR wings, I just can’t find a use for them on light airplanes. Jimstix
 

jedi

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Sahuarita Arizona, Renton Washington, USA
Full disclosure – I love goofy, weird airplanes with bookshelfs to prove it. Low-aspect-ratio (LAR) wings just have no real place on non-goofy general aviation airplanes. Sure, there are structural advantages and “look what I built” pride of the builder. However, these are not compelling reasons to design a LAR light airplane.

Reasons you might want to have a LAR airplane include:

  • Launch into space and reentry into the atmosphere (lifting bodies and shuttle orbiter)
  • Fit into the bomb bay (XF-85) or on a MIR or TIR (JDAM kitted Mk 82’s)
  • Fly faster than the speed of sound (gobs of delta-winged jets)
  • You need improved body lift to maneuver (Standard Missile)
My guess is that you won’t be doing those things.

The opposite of LAR wings is HAR wings – like sailplanes and (wait for it) helicopters.

We all know that sailplanes are efficient (low induced and profile drag). What about helicopters? Long skinny, twisty, droopy HAR blades work much better than short, wide LAR blades having the same blade area. That’s because a key figure of merit in a helicopter rotor is disk area – not blade area. Helicopters barely fly with those HAR blades and will not work with the short, wide LAR blades.

I don’t wish to be a Debbie Downer on LAR wings, I just can’t find a use for them on light airplanes. Jimstix
Tried posting my paper airplane model of a 1.25 Aspect Ratio Super Wing Suit. 50 sq ft area 8 foot span. 4:1 glide ratio.

No joy on drawings or photo. Got to go now.
 
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Sockmonkey

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Apr 24, 2014
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Flint, Mi, USA
Yes, I was thinking basically of a blunt paper airplane shape like the one below, but with the ventral fin bulged at the front to fit the pilot and provide a firewall for the engine. The pilot would access the cockpit through a door in the bulged fin leading to the seat with his/her head in a canopy above the wing. The front of the fin would become a triangular flat
One neat thing is that with the rudder below the wing like that, yawing is going to give you proverse roll.
 

lr27

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Nov 3, 2007
Messages
3,822
Full disclosure – I love goofy, weird airplanes with bookshelfs to prove it. Low-aspect-ratio (LAR) wings just have no real place on non-goofy general aviation airplanes. Sure, there are structural advantages and “look what I built” pride of the builder. However, these are not compelling reasons to design a LAR light airplane.

Reasons you might want to have a LAR airplane include:

  • Launch into space and reentry into the atmosphere (lifting bodies and shuttle orbiter)
  • Fit into the bomb bay (XF-85) or on a MIR or TIR (JDAM kitted Mk 82’s)
  • Fly faster than the speed of sound (gobs of delta-winged jets)
  • You need improved body lift to maneuver (Standard Missile)
My guess is that you won’t be doing those things.

The opposite of LAR wings is HAR wings – like sailplanes and (wait for it) helicopters.

We all know that sailplanes are efficient (low induced and profile drag). What about helicopters? Long skinny, twisty, droopy HAR blades work much better than short, wide LAR blades having the same blade area. That’s because a key figure of merit in a helicopter rotor is disk area – not blade area. Helicopters barely fly with those HAR blades and will not work with the short, wide LAR blades.

I don’t wish to be a Debbie Downer on LAR wings, I just can’t find a use for them on light airplanes. Jimstix
I think you're oversimplifying things a bit here. I think Barnaby Wainfan has shown that a low aspect ratio wing may be suitable for a small, GA aircraft of moderate speed. Assuming that the marketing types are talented enough to sell something that looks weird. The lower price would make that easier, but maybe not enough.

I've heard that the Avro Vulcan's L/D was 18.

Anyone know if there's anything awful about the Dyke or the Verhees Deltas?
 

Riggerrob

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Canada
Dyke Delta and Verhees Delta don’t pitch up for take-off or flare for landing. Their landing gear is fixed at the best angle for both maneuvers. They are flown by the numbers.
Be careful not to get too slow and pitched up too steep, because then induced drag becomes huge.
That makes them simpler to land and take-off but requires a bit of “type” specific training.
 

Riggerrob

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Small del
I think you're oversimplifying things a bit here. I think Barnaby Wainfan has shown that a low aspect ratio wing may be suitable for a small, GA aircraft of moderate speed. Assuming that the marketing types are talented enough to sell something that looks weird. The lower price would make that easier, but maybe not enough.

I've heard that the Avro Vulcan's L/D was 18.

Anyone know if there's anything awful about the Dyke or the Verhees Deltas?
Deltas are much easier to build because of the lowered parts count.

Secondly, deltas have much larger Reynolds numbers making them far more effficient at low air speeds.
Long centre sections can easily be built deep enough to hide most of the pilot, eliminating the need for a dedicated fuselage.

Finally, long chords do not have to be built as precisely to fly well. Consider that 3 or 4 feet (1 metre) is about the minimum that an amateur can build a wing rib accurately.

If life had worked out better, I would be too busy pulling rivets on a Verhees Delta 2 to .....
 

cluttonfred

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I've said it before, but I have always thought the Saab 210 proof-of-concept flying scale model of the Draken fighter (therefore nicknamed "LillDraken") would be a great starting point for fun homebuilt plane. Lose the nose cone and put the engine and cowling where it and the engine air intakes were in the original short-nosed version of the 210. The 210 was about 20' long and 16' span, so about 80 sq ft of wing area, substantially more than a Formula V racer and only a little less than a Sonerai II two-seater. Without the same speed concerns as a supersonic fighter we could reduce the sweep of the forwad section to get a little more area in the same footprint and move the neutral point forward, though the pilot would likely have to be seated further back than the original. It would certianly be a hoot and look very cool! [EDIT: I think my numbers for the original LillDraken are off as this very detailed page shows it about 50% bigger in all dimensions. Still, the 16' span would be appropriate for a small light plane.]




 
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berridos

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madrid
Very nice. Thank for that design. I am currently reading the viggen paper. It was in that direction i wANTED to modify the verhees. Introducing a double delta to add a second vortex at the start of the last extension(sharp L-edge at that corner). The problem the verhees is already nose heavy. Havent come up with a solution to that problem. The original version handles only extrem,ly light motorplants. Suppose i would need to extend a bit the design and place the pilot further back. The view is anyway already lost. Some redundant camera view glasses with double giroscopic gopros.
I have a problem with the rotax rick because of its high noise level. You can become mad after 3 hours travelling.
 
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Voidhawk9

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Timaru, NZ
I agree that would look fantastic. But putting a heavy engine where a hollow nose once was might not work well. :oops:
 

BBerson

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Port Townsend WA
Dyke Delta and Verhees Delta don’t pitch up for take-off or flare for landing. Their landing gear is fixed at the best angle for both maneuvers. They are flown by the numbers.
I think more aircraft could be made this way. The tail can ride low, this gets the CG lower without getting less prop clearance. Some C-182/206 bush planes in Alaska are loaded very tail low. Puts less weight on the nosewheel.
 

rotax618

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Evans Head Australia
From my experiments, I found that the SAAB type double delta is the least stable at low speed and high alpha. Just as I found, the SAABs had a reputation for deep unrecoverable stall.
I found the most stable planform was an ”Inverse Zimmerman” or straight leading edges approximating to that shape.
F3499B9B-D037-4EB3-9BE5-0056AF72DDE8.jpeg575B097E-CFEE-42EF-B423-0BAD4D94BEF6.jpeg3B5A3D6B-C956-48B3-B6EB-FC64631470F1.jpeg1A624ABA-EFD4-410B-8D00-85128CF2A2B9.png
 

cluttonfred

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I agree that would look fantastic. But putting a heavy engine where a hollow nose once was might not work well. :oops:
I hear you, but keep in mind that this would be a much, much lighter aircraft with far lower wing loading and the single largest weight to consider would be the pilot. Here's a 3-view of the final interation of the Saab 210 (looking much more like the full-size Draken, but never mind that) as a reference. From the position of the main landing gear, I would guess that the CG is located about even with the kink in the leading edge, the point where the sweep "cranks" outwards. So the microlight version would have the pilot seated there, with the headrest (or just the bubble canopy) going right to the leading edge of the vertical fin. With more structure and the main gear aft of that point, the engine located about where the intakes are would be *necessary* to balance the plane.
 

Himat

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Norway
Full disclosure – I love goofy, weird airplanes with bookshelfs to prove it. Low-aspect-ratio (LAR) wings just have no real place on non-goofy general aviation airplanes. Sure, there are structural advantages and “look what I built” pride of the builder. However, these are not compelling reasons to design a LAR light airplane.

Reasons you might want to have a LAR airplane include:

  • Launch into space and reentry into the atmosphere (lifting bodies and shuttle orbiter)
  • Fit into the bomb bay (XF-85) or on a MIR or TIR (JDAM kitted Mk 82’s)
  • Fly faster than the speed of sound (gobs of delta-winged jets)
  • You need improved body lift to maneuver (Standard Missile)
My guess is that you won’t be doing those things.

The opposite of LAR wings is HAR wings – like sailplanes and (wait for it) helicopters.

We all know that sailplanes are efficient (low induced and profile drag). What about helicopters? Long skinny, twisty, droopy HAR blades work much better than short, wide LAR blades having the same blade area. That’s because a key figure of merit in a helicopter rotor is disk area – not blade area. Helicopters barely fly with those HAR blades and will not work with the short, wide LAR blades.

I don’t wish to be a Debbie Downer on LAR wings, I just can’t find a use for them on light airplanes. Jimstix
Is really HAR more efficient?
When people say a high aspect ratio wing is more efficient, they usually or often fall back and cite the classic induced drag coefficient:

Cdi = Cl^2/(pi*aspect ratio* efficiency factor)

And skip two underlying assumptions:
  • Constant wing area.
  • Evaluated at the same speed.
That is, wings with the same area are compared at a fixed speed. Now, instead of keeping area constant, keep the wing span constant. You will find that with fixed wing span and evaluated at the same speed, the Cdi rises with increasing aspect ratio. Then what do that tell us about aspect ratio and efficiency?
 

berridos

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madrid
With the specs and performance at hand i really feel that a small delta as a travel machine fits the purpose much better than a cessna in all aspects. The only goal i have, is to reduce the landing speed by 5 knots in order to land at ultralight airports. Maybe its achievable with thorough scsle testing of devices and slight modifications
 

Mavigogun

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Progressive Texas
So the microlight version would have the pilot seated there, with the headrest (or just the bubble canopy) going right to the leading edge of the vertical fin. With more structure and the main gear aft of that point, the engine located about where the intakes are would be *necessary* to balance the plane.
Now you've got a really horrible field of view- for me, a joyless prospect. Weinfan manages that with a relatively blunt nose and pilot in the typical peering-around-the-engine position... plus foot windows- not fantastic, but at least affording sufficient forward-side-down view to not require locating by hunches and hope on approach. I'm inclined to accept the head ache of moving the engine to push, pilot forward, and avoid the Horten H.IV pilot position in favor of something closer to, say, the Wild DoubleEnder. I fear the intertial consequences of placing mass at extents, though- when at the wingtips, the wing lags input, is more difficult to redirect; longitudinally, I worry about similar response problems and a propensity to tuck or tumble.
 

Urquiola

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Madrid, Spain
That Scroggs Dart could have potential, maybe using Dacron over aluminum tubes, ultralight-style construction. I'd give it triycle gear and a door in the ventral "fin" for accessing the cockpit from below. I wonder if you could get away with a kink in the ventral fin so that it would be widest at the cockpt but come together to a single tail post so there would no longer be an opening at the rear
If you can build an Scroggs 'Flying Dart' equal or below 114 kg empty weight, it's ultralight, and with less than 250 cm wingspan, it could ride on roads, three wheels is car, can be driven with a car license, two wheels is motorcycle, needs a byke license. What I'd like having in it is an 'A' tail unit, to have induced rolling to right sense when banking, also propulsion by ducted fan or jet inside fuselage, the 'Trompe' way (see Wikipedia), if a Jet Delta has no problem without the propeller washout, so will an smaller one. Mirage III had wing tips bend downwards, something as 'mini-winglets', this reduces Dutch Roll, and also wingtip wake turbulence; an small business jet was sent to scrap after entering A-380 wake turbulence. Turbulence from this machine is so huge, that blocks airstrips for long, in order of having it slowed down. The civilian verison of B-36: XC-99, was rejected by companies, perhaps it would have stuck airfield passenger and luggage handling power. Blessings +
 

Urquiola

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The Scroggs prototype was built with welded metal tubes covered by something, the same way as Facetmobile. I don't like plywood, sooner or later, weather will bite on it, but there are many other materials, also the structure in Milt's 'Little Bird', composite or fibre upper and lower halves tied togheter, may work. I don't have an Airfoil for the 'Flying Dart'. Blessings +
 
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