Very low aspect ratio planes?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Inverted Vantage, Oct 30, 2009.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Oct 2, 2015 #581

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,567
    Likes Received:
    402
    Location:
    Flint, Mi, USA
    Is that meant to be like a full wing-body or just the wing?
     
  2. Oct 2, 2015 #582

    WonderousMountain

    WonderousMountain

    WonderousMountain

    Well-Known Member

    Joined:
    Apr 10, 2010
    Messages:
    1,855
    Likes Received:
    192
    Location:
    Clatsop, Or
    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
     
  3. Oct 2, 2015 #583

    cluttonfred

    cluttonfred

    cluttonfred

    Well-Known Member

    Joined:
    Feb 13, 2010
    Messages:
    6,351
    Likes Received:
    2,208
    Location:
    World traveler
    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
     
  4. Oct 2, 2015 #584

    cheapracer

    cheapracer

    cheapracer

    Well-Known Member

    Joined:
    Sep 8, 2013
    Messages:
    5,059
    Likes Received:
    3,327
    Location:
    Australian
    From what i have read, the wing shape is 180 degrees out, the wide edge should be the tail, not the leading edge.
     
  5. Oct 2, 2015 #585

    WonderousMountain

    WonderousMountain

    WonderousMountain

    Well-Known Member

    Joined:
    Apr 10, 2010
    Messages:
    1,855
    Likes Received:
    192
    Location:
    Clatsop, Or
    Screenshot 2015-10-02 at 09.23.58.jpg

    Clearing out some room in the center, hmmmnn..
     
  6. Oct 2, 2015 #586

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,567
    Likes Received:
    402
    Location:
    Flint, Mi, USA
    I was under the impression that the shape gave it the advantages of a FSW without being twitchy?
     
  7. Oct 19, 2015 #587

    Starjumper7

    Starjumper7

    Starjumper7

    Well-Known Member

    Joined:
    Sep 28, 2015
    Messages:
    201
    Likes Received:
    31
    Location:
    Ecuador
    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?
     

    Attached Files:

    Last edited: Oct 19, 2015
    Battler Britton likes this.
  8. Oct 19, 2015 #588

    BJC

    BJC

    BJC

    Well-Known Member

    Joined:
    Oct 7, 2013
    Messages:
    8,887
    Likes Received:
    5,737
    Location:
    97FL, Florida, USA
    Of course it is possible, assuming that, in violation of current laws, you are able to get the necessary dilithium crystals.


    BJC
     
  9. Oct 19, 2015 #589

    Starjumper7

    Starjumper7

    Starjumper7

    Well-Known Member

    Joined:
    Sep 28, 2015
    Messages:
    201
    Likes Received:
    31
    Location:
    Ecuador
    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?
     
  10. Oct 19, 2015 #590

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,567
    Likes Received:
    402
    Location:
    Flint, Mi, USA
    Maybe something like this.
    [​IMG]
     
  11. Oct 19, 2015 #591

    BJC

    BJC

    BJC

    Well-Known Member

    Joined:
    Oct 7, 2013
    Messages:
    8,887
    Likes Received:
    5,737
    Location:
    97FL, Florida, USA
    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
     
  12. Oct 19, 2015 #592

    Starjumper7

    Starjumper7

    Starjumper7

    Well-Known Member

    Joined:
    Sep 28, 2015
    Messages:
    201
    Likes Received:
    31
    Location:
    Ecuador
    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.
     
  13. Oct 19, 2015 #593

    BJC

    BJC

    BJC

    Well-Known Member

    Joined:
    Oct 7, 2013
    Messages:
    8,887
    Likes Received:
    5,737
    Location:
    97FL, Florida, USA
    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
     
  14. Oct 19, 2015 #594

    Starjumper7

    Starjumper7

    Starjumper7

    Well-Known Member

    Joined:
    Sep 28, 2015
    Messages:
    201
    Likes Received:
    31
    Location:
    Ecuador
    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.
     
  15. Oct 19, 2015 #595

    WonderousMountain

    WonderousMountain

    WonderousMountain

    Well-Known Member

    Joined:
    Apr 10, 2010
    Messages:
    1,855
    Likes Received:
    192
    Location:
    Clatsop, Or
    In case anyone does want to hold an ultra-unlimited race,

    I've got a bi-turbo V12 2-stroke for sale :gig:
     
  16. Oct 20, 2015 #596

    cheapracer

    cheapracer

    cheapracer

    Well-Known Member

    Joined:
    Sep 8, 2013
    Messages:
    5,059
    Likes Received:
    3,327
    Location:
    Australian
    Not big on the subject, I remember now I got the impression (about the inverse zinnerman) from here ..

    http://www3.nd.edu/~mav/auvsi/torres.pdf
     
  17. Oct 23, 2015 #597

    Urquiola

    Urquiola

    Urquiola

    Member

    Joined:
    Aug 23, 2013
    Messages:
    11
    Likes Received:
    0
    Location:
    Madrid, Spain
    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
     

    Attached Files:

  18. Oct 24, 2015 #598

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,567
    Likes Received:
    402
    Location:
    Flint, Mi, USA
    Gave it a read. Sounds reasonable but I wouldn't mind more data.
     
  19. Jan 3, 2016 #599

    BigBen

    BigBen

    BigBen

    Well-Known Member

    Joined:
    Aug 14, 2011
    Messages:
    55
    Likes Received:
    1
    Location:
    Sebring,FL
     
  20. Jan 4, 2016 #600

    Urquiola

    Urquiola

    Urquiola

    Member

    Joined:
    Aug 23, 2013
    Messages:
    11
    Likes Received:
    0
    Location:
    Madrid, Spain
    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
     

Share This Page

arrow_white