Very low aspect ratio planes?

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Riggerrob

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Dear Cluttonfred,

Excellent stealthy configuration.

In your post #63, which direction is your plane flying?
Hah!
Hah!
When you invade "bad guy land" their first few shots will miss you by 45 degrees!
Maybe they will swear off vodka.
Maybe they will die laughing.

What type of shelving do you use to store a dozen or so "square" planes in one hanger?
Hah!
Hah!
 

Riggerrob

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If you install (Piana-Canova) wing-fold hinges on the diagonal, they would fold into neat little rectangles and easily stack on shelves. If your start with a square/diamond shaped Piana-Canova, the folded shape is the same length as a (right) leading edge, but folded width is only half the span of that (right) trailing edge. The fold hinge starts in the middle of the left leading edge and goes diagonally to the middle of right elevon. When folded, the top view is a rectangle with a propeller protruding from one corner and a rudder protruding from the (diagonally) opposite corner.

Engine, cockpit, nosewheel and main wheels all stay attached to the right-ish (leading edge) part of the airframe when folded. Only the tail bumper/wheel lifts off the floor when folded.

Sorry, I tried to draw this configuration, but spell-check - bless its soul - confusemucated my drawing.
 
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cluttonfred

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flitzerpilot, I like the exposed motor and variable-length engine mount as a solution for dialing in the CG.

One thing that concerns me about many of these designs is the use of a central elevator which washes out a big chunk of the wing area at low speed when you need it most. That also seems like a way to encourage tip stall at low speed.

I think straight lines are easier to build than curves so I wouldn’t go with the Arup/Zimmerman planform but it’s easy enough to approximate with straight taper.

Riggerob, I don’t quite understand the wing fold setup you’re suggesting but I think a straight carrier-type upward fold could work well with a span of just 16', even fit through the door of a 20' shipping container.
 
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rotax618

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If the LAR is a high wing and around 16’ span then 4’-5’ outer panels can be folded down for storage.
Pitch control surfaces on the rear of a very wide chord wing need to be very wide to prevent small movements operating in turbulent air (dead centre), another approach is to either use “Junkers” elevator/elevons or a seperate horizontal stabiliser mounted high up on the fin ( like Arup 4).
the wing could be made triangular but with a curved trailing edge control surface, this could provide the required reflex.
 

Riggerrob

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Dear cluttonfred,
Piana-Canova, diamond, wing planform....
A 16 foot wing span means that each edge is 11.3 feet long, so it can fold into a rectangle 11.3 feet by 5.7 feet.
The hinge line starts in the middle of the left leading edge and extends (aft of the cockpit) to the right elevon. The right elevon is made in two pieces to allow it to fold.
The right leading edge lays parallel with the long axis of the shipping container, while the folded right elevon sits width-wise against one end of the ISO container. The thrust line is diagonal (45 degrees) to the length of the ISO shipping container. This would only work with a 2-bladed propeller. …. and remember to turn the propeller vertical before slamming the door! IOW, thetractor propeller is shoved deep into a corner of the shipping container.

Might as well go for a full 26 foot span to fill out the hypothetical 20 X 10 X 10 ISO shipping container. That makes each leading edge 18.3 feet long and folded width is just over 9 feet. … for a total of 81 square feet of wing area. Extra wing area always helps when flying with small engines.

Does that make more sense?
Sorry, I tried to draw a diagram, but spell-check was too-helpful!!!!!!

I am not sure about the finer points of diamond-shaped wings, but small deltas land and take-off at the same angle of attack. The danger arises when they fly at too steep an angle of attack, then induced drag gets ridiculous! IOW At steep angles of attack, sharply swept (e.g. 45 degrees) leading edges hang on their massive tip vortices, with the rest of the wing contributing little lift. In that scenario, pulling the nose up more only increases rate of descent until you can no longer "power" your way out of a bad approach.
Smarter delta designers (e.g. Dyke and Verhees) just fix landing gear at the best angle for take-off. One Dyke Delta pilot reported that he just sets trim, advances the throttle and lets it take-off by itself.
 

Urquiola

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Perhaps a good use of Short Aspect Ratio wings could be a Triplane version of Bumble Bee II, Guinness record of Smallest Airplane in the world, but its stalling speed is faster than top speed allowed for cars in highways
Would a Triplane Bumble Bee be allowed on roads, as 'Flying Motorcycle'? Top width for road vehicles is 249 cm, 8.17 ft. I imagine also a flat surface linking all wings in the tip, as in a 'Box' wing, acting as an aileron, 'V' surface, winglets. Blessings +
 
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berridos

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It can bearely sustain itself in the air. Rotation far to early.
Urquiola, are you sure its 2,49m? i read 2,60 or 2,55. Its an important design parameter in order to trailer my delta, and make the wing extension as tiny as posible.
 

Urquiola

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Yes, I'm sure enough, top width allowance depends on type of vehicle: buses, trucks, are allowed a bit wider, but for cars, definitely is 250 cm, here in Spain, probably same all over Europe.
You can consult sección general de tráfico
If you fall short, it's bad, but excess is even worse. (Don Mendo's revenge)
Blessings +
 
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Urquiola

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Better preventing than spending on cure...
Blessings +
Somenone with experience in Roy Scroggs 'Flying Dart'? Pat US1848578;
They said something having flown with an OX-5, as Scroggs' Dart, would fly with anything, Besler Steam Plane first engine was also an OX-5
 

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Urquiola

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Would you say the leading edges are sharpened? I would say no, but i am not sure
I have some references about Delta Wing Planform: 'Aerodynamic Characteristics of Slender Delta Wing with Low Dorsal Fin', Xuanshi Meng et al, 45th AIAA meeting, 2007-1272; 'Experimental Determination at Subsonic Speeds of the Oscillatory and Static Lateral Stability Derivatives of a Series of Delta Wings with Leading Edge Sweep from 30º to 86.5º', William Letko, NACA RM L57A30; 'Delta Wings below and above the Speed of Sound', Robert T Jones, NACA TN 1032; 'Planform Effects for Low-Reynolds-Number Thin Wings with Positive and Reflex Cambers', Z J Chen and N Qin, Journal of Aircraft, May-June 2013; 'Experimental Investigation of Blunt-Edged UTM Delta Wing VFE-2 Configurations at Low Reynolds Number', Muhammad Zal Aminullah bin Daman Huri et al, I.RE.M.E, 2018; 'Influence of Reynolds Number on Vortex Flow over a NonSlender Delta Wing', Lan Chen, AIAA, 2010; 'Langley Full-Scale-Tunnel Investigation of Maximum Lift and Stability Characteristics of an Airplane having Approximately Triangular Plan Form (DM-1 Glider)', J C Lowell, H A Wilson, NACA RM L7F16, -this is Alexander Lippisch L-13; 'The Subsonic Lateral and Longitudinal Static Stability Characteristics up to Large Angles of Sideslip for a Triangular-Wing Airplane Model Having a Ventral Fin', by Donald A. Buell and Bruce E. Tinling, NACA RM A56H06. For sure, this:
Blessings +
 

cluttonfred

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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
 
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cluttonfred

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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


scroggs.jpg

The Scroggs is neat but it looks like the visibility would be crap unless you stuck a cockpit bubble on top.
 
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