Very low aspect ratio planes?

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WonderousMountain

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Just the wing.

I'm going to add a center-line half pod below, leaving the upper surface undisturbed. Then a full span box trim-plane, I'm not sure what to call it, but basically a junkers flap.

On reflection, I need to move the left and right tube connection apart, and clear some space for a pilot.

Sometimes I like to take a few days before going forward.

LuPi
 

cluttonfred

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Hove you considered the option of an otherwise conventional design with a low AR wing? Something like the Farman "Carte Postale" or the Fike E?

494033855_db278817ca.jpg farman_sport_3v.jpg Fike E.jpg FikeE001.jpg

Check out some Peanut and Pistachio flying scale model plan sites for inspiration. Because those classes are limited by span, not scale. low AR designs are common because they give more wing area within the size limits.

Cheers,

Matthew
 

cheapracer

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We are approaching the concept of the flying horseshoe of the Arup design :)
View attachment 43509
It had an engine up in front, but it was a simple direct drive, with good flying characteristics.
I'm wondering what banned Topspeed100 would have come up with for a LAR plane!
Rki
From what i have read, the wing shape is 180 degrees out, the wide edge should be the tail, not the leading edge.
 

Starjumper7

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I have a new friend who might possibly be interested in building an unlimited racer, and so ... This is an improvement over the previous twin V8 I had drawn, with all the focus on this one going towards streamlining and lightness.

I hope for feedback on this idea, looking for suggestions and opinions as to whether or not this type could beat the current unlimiteds

This has the pilot in the Left side engine nacelle, balanced by the cooling system on the Right side. It has a span of 16 ft, and an ~effective wing area of 180 ft (doesn't count the elevator and elevon area). I envision using two of the aftermarket aluminum (monster) V8 big block race engines that come in 600 - 700 cu. in. size, turbocharged. I forgot, but I've think they can put out over 1000 hp with excellent reliability. Shown with planetary, in line, reduction gears.

The distance between engine centerlines is eight feet, and so the primary structure, the main spar between the engines which also serves as the engine mounts, is only six feet long, consisting of a beefy round steel tube. The rest of the spar going out to the wing tips can be light because its so short. From there a more or less typical steel tube framework, with wood ribs and plywood wing skins.

Everything, all the wing airfoils, the engine nacelles, and the cockpit, are 40% laminar airfoil shapes.

I guess the weight could come in at 2500 lb so thats a 25 lb/ft wing loading, and could be around 1 lb/hp power loading.

Last but not least, to address the two deadly sins of this type of twin engine aircraft; to keep it from becoming a frisbee if one engine fails, and to keep it from flying like a brick with engines out (both engines must go offline if one fails), it should have something like a 50 hp electric motor added to each reduction gear, and enough light weigh batteries for a few minutes of power, enough to get you to the crash site. It would also require some kind of clutches with automatic disconnect to immediately isolate the engines from the propellers. The good engine could then help supply the batteries with a beefy alternator.

The red boxes behind the engines represent turbocharger and intake stuff, and the blue in the right side nacelle is the area for the liquid cooling system. The right side nacelle is shown looking at it from the center, showing the wing center section. The left side nacelle is shown looking from the outside, showing the wing tip and elevon.

This broke the excel spreadsheet because with only 1000 total hp it gave impossible top speed and ROC.

It should have higher top speed in the straights but maybe loose too much steam in the turns?
 

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BJC

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I have a new friend who might possibly be interested in building an unlimited racer, and so ... This is an improvement over the previous twin V8 I had drawn, with all the focus on this one going towards streamlining and lightness.

I hope for feedback on this idea, looking for suggestions and opinions as to whether or not this type could beat the current unlimiteds

This has the pilot in the Left side engine nacelle, balanced by the cooling system on the Right side. It has a span of 16 ft, and an ~effective wing area of 180 ft (doesn't count the elevator and elevon area). I envision using two of the aftermarket aluminum (monster) V8 big block race engines that come in 600 - 700 cu. in. size, turbocharged. I forgot, but I've think they can put out over 1000 hp with excellent reliability. Shown with planetary, in line, reduction gears.

The distance between engine centerlines is eight feet, and so the primary structure, the main spar between the engines which also serves as the engine mounts, is only six feet long, consisting of a beefy round steel tube. The rest of the spar going out to the wing tips can be light because its so short. From there a more or less typical steel tube framework, with wood ribs and plywood wing skins.

Everything, all the wing airfoils, the engine nacelles, and the cockpit, are 40% laminar airfoil shapes.

I guess the weight could come in at 2500 lb so thats a 25 lb/ft wing loading, and could be around 1 lb/hp power loading.

Last but not least, to address the two deadly sins of this type of twin engine aircraft; to keep it from becoming a frisbee if one engine fails, and to keep it from flying like a brick with engines out (both engines must go offline if one fails), it should have something like a 50 hp electric motor added to each reduction gear, and enough light weigh batteries for a few minutes of power, enough to get you to the crash site. It would also require some kind of clutches with automatic disconnect to immediately isolate the engines from the propellers. The good engine could then help supply the batteries with a beefy alternator.

The red boxes behind the engines represent turbocharger and intake stuff, and the blue in the right side nacelle is the area for the liquid cooling system. The right side nacelle is shown looking at it from the center, showing the wing center section. The left side nacelle is shown looking from the outside, showing the wing tip and elevon.

This broke the excel spreadsheet because with only 1000 total hp it gave a top speed of over 1400 knots and a ROC of over 495,000 ft/min, not possible.

So, do you think it's possible?
Of course it is possible, assuming that, in violation of current laws, you are able to get the necessary dilithium crystals.


BJC
 

Starjumper7

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To compare this to Rare Bear. The weight is one fourth. The power to weight ratio is four times better, the frontal area is one sixth and the power is half so the power to frontal area ratio is three times better. The wing loading is around 70%, and the span loading is 2.5 times better, so how could it not beat Rare Bear?
 

BJC

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IIRC, there is no Unlimited racing class at Reno, or any place else in the USA, where such a design could compete in an organized race.


BJC
 

Starjumper7

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Well, anyone can race anything anyone wants anywhere anyone wants, but what is it that makes you say these wouldn't be allowed to compete in any class? Wait, I remember now, unlimited means it has to weigh several tons because that race is controlled by stick in the mud coward pigs. Well screw them, someone can go around the course when they aren't looking and beat them anyway.

Some day, when the controller pigs have died away, there will be a REAL unlimited class, maybe even sooner... in a different part of the world.

In any case, in the spirit of low aspect ratio planes, we could still contemplate how easy it would be to beat the old warbirds with a modern XF5 type.

Monkey, that's a type I've tried before too, it looks good. Mine is smaller though ... I never thought I would be bragging about that.
 

BJC

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Well, anyone can race anything anyone wants anywhere anyone wants, but what is it that makes you say these wouldn't be allowed to compete in any class? Wait, I remember now, unlimited means it has to weigh several tons because that race is controlled by stick in the mud coward pigs. Well screw them, someone can go around the course when they aren't looking and beat them anyway.

Some day, when the controller pigs have died away, there will be a REAL unlimited class, maybe even sooner... in a different part of the world.

In any case, in the spirit of low aspect ratio planes, we could still contemplate how easy it would be to beat the old warbirds.

Monkey, that's a type I've tried before too, it looks good. Mine is smaller though ... I never thought I would be bragging about that.
One of the results of Jimmy Leeward's crash at Reno was a new class that has "unlimited" in its name, but really is just warbirds. The 2014 Sport Class winner, a Glasair III, would have finished seventh or so in the Unlimited Gold, with a speed of over 400 MPH.

If there are no "stick in the mur cowards" where you live, then why aren't they hosting a truely unlimited airplane race?

If a low aspect ratio airplane can beat the current class of pylon racers, then build one. But you might want to take note of the fact the the people who are doing, rather than contemplating, have evolved to higher aspect ratios to be faster.


BJC
 

Starjumper7

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There are 'stick in the mud cowards' in all parts of the world, its human nature ... which functions as follows: Whenever anything, whether it is a political party, a religion/church, a corporation, a small business, a social club, etc. is new then it is revolutionary, open, and stimulates progress, in other words, a force of light. Later, if they are successful and they mature, every one of them turns into a force of darkness, conservative, closed, limited, and restricting progress. This is human nature ... in general.

Thanks for the comment about span loading. The pancake cartoons just posted actually have a span loading that is two or three times lower than ye olde warbirds but more could be better. The saving 'aspect' of it could be that it makes the structure so much lighter, and the wing loadings are lower. Lower wing loading makes up for high span loading to some degree.
 

Urquiola

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This is known, this is not exactly a homebuild airplane, it's the development of the Arup flying wing designs, but it has a short aspect ratio. What I can't imagine is why it's designed with an 'inverted dihedral'; perhaps a wing thickness tapering upwards with the upper surface line flat, as in ordinary dihedrals, may avoid or mitigate the upside down drive from ground effect of a flat or negative dihedral wing. Any suggestion? Thanks, + salut
 

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BigBen

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G'day, I have posted this design in the light stuff forum area, but think I may get more feedback in Aircraft?Design etc.

I have been sketching a low aspect ratio Ultralight (Australian ultralight not US Part 103) , I have used the Inverse Zimmerman planform, which is supposed to have the best CL of the LA planforms. My design overcomes some of the criticism of this genre of aircraft. The aircraft is intended for registration in the Australian 95.10 or Amateur Built Category.

1. The UC is short but the rotation angle is 24deg.
2. Visibility is excellent in most directions.
3. Access is easy.
4. Junkers style Elevons prevent blanketing by the relatively thick wing.
5. The wings can fold for transportation and storage.

Tom,
In this design you appear to be applying a "smoothmobile" type of nonfaceted airfoil with a sharp leading edge instead of the faceted airfoil your lifting bodies utilized. Have you developed a foil cross section for this aircraft? If so, I would appreciate your sharing the coordinates and any aerodynamic data if they have been modeled.
Also I like the high wing solution for both vision and access improvements. Do you see any problems from having the CG enough below the wing to introduce a pendulum effect that negates a lot of the benefit of the very long chord or do you think there is still plenty of elevator power available?
Thanks and have a great New Year.
 

Urquiola

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Hi!: as discussed, you may probably like having a look at the documents:
* NACA Research Memorandum nº L7F16, of August 1947: 'Langley full-scale-tunnel investigation of maximum lift and stability characteristics of an airplane having approximately triangular plan form (DM-1 Glider), J Calvin Lovell and Herbet A Wilson.
* NACA Report Nº 835: 'Properties of low-aspect ratio pointed wings at speeds below and above the speed of sound', Robert T Jones
* NACA Technical Note Nº 1032, Robert T Jones
* NASA AIAA 2001-0311: 'Flying Wings/ Flying Fuselages', Richard M Wood and Steven X S Bauer
* NACA Research Memo RM L57A30: 'Experimental determination at subsonic speed of the oscillatory and static lateral stability of a series of Delta Wings with leading edge sweep from 30º to 86.5º', William Letko
* NASA PAV Report (about a larger: 'Facetmobile')
* 'A novel all wing airplane', Raoul Hofmann, Popular Aviation, March 1935, pgs. 195-196 (This is the ultimate development of Arup Flying Wings, antecessors of: 'Flying Pancake')
All can be retrieved by any search engine, also some info about NASA Flying Bodies that appears both in document and YouTube video form may have a connection. Good luck, and good year 2016! Regards, + salut
 
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