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Thread: Smallest possible ultralight for real men 230lbs

  1. #1
    Registered User erkki67's Avatar
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    Smallest possible ultralight for real men 230lbs

    Hi

    I wonder how small an easy to build ultralight can be, to haul a 230lbs Pilot and T/O and land almost everywere?

    I belive that the ideal would be around a design of the Texas Parasol or the nonexistant BAP!

    Another design concept would be the ZJ-Viera but it should be build in aluminium and wood and no costly composites.

    Also a candidate for a brush-up would be the Birdman TL1A with the engine up in front and ailerons instead of spoilers.

    Ideal would be too, that the whole bird is powered be a B/S Vanguard or similar engine of Kohler, Generac, Fuji, Lifan, Kawasaki, Honda and others!

    Any kind of concept is welcome, as long as it powered by a 4stroke!

    Bst rgds

    Erkki

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    Registered User Hot Wings's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Conventional wisdom and practices yield conventional results. If that is good enough for you:
    Problem solved.

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    Registered User fly2kads's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Something along the lines of the Legal Eagle XL? Milholland uses his own half VW, but I don't see any reason why it couldn't be adapted to other types of engines. You'd obviously need to pay attention to weight, C.G., and prop clearance.

    Legal Eagle XL by Leonard Milholland

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    Moderator autoreply's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    20 kg (45 lbs) except the engine should be possible.

    Take note that for you an ultralight is vastly different from what most users will think you mean. You are talking about a very light airplane (MLA), but in the US an "ultralight" is a very slow aircraft with below 25 kts stall.

    Basically the distinction you'll find is mainly on stall speed. 25 kts will give you a very vulnerable aircraft in terms of crosswind and so on, but a much higher stall speed will keep you out of some airports. So how small is the smallest runways you want to land on?

    Do you want a 3-axis aircraft, or is a trike also ok?
    Last edited by autoreply; August 12th, 2011 at 06:58 PM.
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    Registered User mstull's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Stall speed is the limiting factor in small size, if you care about being legal. It takes an awful lot of wing area to pass the stall speed limit. The lighter the plane, it takes a little less... but it's still a lot. You can add flaps or flaperons to use somewhat smaller wings.

    It is possible to use special lift devices to make even smaller wings pass the stall speed limit, like slotted leading edges and STOL wing tips. But the added weight, cost, and/or complexity of making and/or supporting them is a pretty big issue. But if it's your goal to make the plane as small as possible, you'd use those and flaps over 50% of span.

    Most existing U/Ls don't have enough wing area to pass the stall speed limit... particularly the smaller ones. Manufacturers routinely lie about the stall speed of their smaller wings. When pressed, they'll say that's what their customers want to buy. Indeed, few U/L pilots care about being completely legal.

    But cute little planes are not legal U/Ls in the USA.
    Mark E. Stull
    mstull@wtxs.net

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    Registered User BBerson's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Why is it that large people are attracted to small aircraft?
    The laws of physics dictate that larger people will need larger aircraft.

    Perhaps the question should be: "what is the smallest practical wingspan of an ultralight for a 230 pound pilot?"

    The Backyard Flyer flew everday at Oshkosh with a 4-stroke Generac.
    BB

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    Registered User erkki67's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    my runway, if I can call it that way, is 200m (650') long on a slight downhill slope.

    An ideal ultralight would be a unstrutted lowwing plane with a stallspeed around 24 to 30 knts.

    The weight should be around 250 to 270lbs.

    bst rgds

    Erkki

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    Moderator autoreply's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Quote Originally Posted by erkki67 View Post
    my runway, if I can call it that way, is 200m (650') long on a slight downhill slope.
    Okay, so realistically speaking, you're looking at something with 45 kts or less stall.
    Even a Cri-Cri can do that, so you have a pretty wide range of options. The Verhees Delta is another one that fits in what you describe, albeit it's a delta, not a low wing.
    An ideal ultralight would be a unstrutted lowwing plane with a stallspeed around 24 to 30 knts.
    Do you know the Sirocco?
    Kennis vermenigvuldig je door het te delen.
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    Registered User erkki67's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    the cricri is not for offairport use and my runway is a field were cows are, so nothing realy flat, I need something for offairport use.

    sturdy but ultralight and if possible foldable or at least storable in a freightcontainer 40' which is my hangar.

    bst rgds

    Erkki

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    Registered User erkki67's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    I had hopes at the new Aero-max from JDT, but they didn't even show up at sun n'fun this year neither at oshkosh to see and feel that bird.

    Indiana is not that far from Oshkosh, so I think that they are far from being ready to distribute their Aero-Max.

    And their suggested selling price was way overpriced by at least 50% ! :-(

    I've the plans of the LE and the XL, but it's not sturdy and simple enough.

    The Airbike is unfortunatly out of production and the Jordan lakes aero has not been spreading large enough, I wonder why?

    My very best rgds

    Erkki

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    BDD
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    Re: Smallest possible ultralight for real men 230lbs

    As an ultralight the stall speed (given), wing CL max (provided you really rotate enough to achieve that), and gross weight will determine your minimum wing area and therefore minimum "size". Flaps would also help reduce that wing area.
    For a plane that is minimized in wing area while meeting the legal requirements for a true Part 103 ultralight, I would just make slightly faster landings than the minimum possible that way you are partly protected from following wind gusts removing your lift at the worst possible moment.

    A biplane or tandem wing plane would minimize the size of the package while providing ample wing area. It is also possible to make biplane wings very strong because they essentially form very deep wire or strut braced trusses the way the wings are joined. Check the useful weight of a Hiperlight, 257 pounds, span 21 ft. This may be your winner. I would be a bit concerned about being able to exit the plane quickly in an emergency.

    The SR-1 Enterprises Hornet biplane claimed a useful load of 425 pounds and +8.8 G's but the wing span is 32'-10". This was sort of a sesquiplane and as a biplane it could have done all this and achieved an even stronger wing structure with less span.
    The Ultravia LePelican (sort of a favorite of mine, and 4 stroke Cushman) claimed a useful load of 240# but it has a long wing to get the wing area, 37 ft. As a biplane it could have sorter wings.
    The Lazair claimed a useful load of 320# or so. Span 36'-4".
    Mitchell Wing B10 useful load: 345#, span: 34 ft. I'd be concerned about the possibility of tip stalls and maybe some other issues. If someone took this approach and lessened the span but increased the chord you could get towards what you are looking for with an ample useful load. You could think of something like a Facet Opal with adequate wing area to be an ultralight. I know I do.

    The biplane or tandem wing though should be the most compact. Other than that, go to a very large chord, low aspect ratio monoplane.

    An ultralight delta wing plane would pack a lot of area into a short span with less span efficiency. It could do what you want but I don't think any exist. There would be issues of possibly ending up on the wrong side of the power curve when taking off and landing. It is a very interesting possiblity however to me. You might think of your CRi Cri fuselage....and maybe even the engine arrangement but with a large area delta wing. The engine/prop/ thrustline and landing gear locations and length would have to be thought out to clear the prop, not fly into the pilot in a hard landing (something I care about but many others seem to practically invite) and to rotate easily for take off and landing. An Arup or "flying pancake" plan form would work too.
    Last edited by BDD; August 14th, 2011 at 01:43 PM.

  12. #12
    Registered User BBerson's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Quote Originally Posted by BDD View Post
    Other than that, go to a very large chord, low aspect ratio monoplane.
    This is my recommendation as well.
    My RC models of aspect ratio 3 seem to work well. Pick a reasonable span for low induced drag and then add wing area (wing chord) as needed to meet the minimum stall speed needed.
    BB

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    Re: Smallest possible ultralight for real men 230lbs

    Quote Originally Posted by BDD View Post
    As an ultralight the stall speed (given), wing CL max (provided you really rotate enough to achieve that), and gross weight will determine your minimum wing area and therefore minimum "size". Flaps would also help reduce that wing area.
    The biplane or tandem wing though should be the most compact. Other than that, go to a very large chord, low aspect ratio monoplane.

    An ultralight delta wing plane would pack a lot of area into a short span with less span efficiency. It could do what you want but I don't think any exist. There would be issues of possibly ending up on the wrong side of the power curve when taking off and landing. It is a very interesting possiblity however to me. You might think of your CRi Cri fuselage....and maybe even the engine arrangement but with a large area delta wing. The engine/prop/ thrustline and landing gear locations and length would have to be thought out to clear the prop, not fly into the pilot in a hard landing (something I care about but many others seem to practically invite) and to rotate easily for take off and landing. An Arup or "flying pancake" plan form would work too.
    I hear you Erkki,

    I have scetched several AC for my 247 lbs mass ( luckily now only 226 lbs due to cycling )...my latest is a twin with sorta pancake forward sweep canard ( no the canard is not forward swept ). It looks hot and is really small but wingarea nearly double the Cri Cri. I intent to create lite structure and have surface effect so that it'll help to gain speed and clear the take off roll with wheels early...I dunno if that works but it looks hot with two fins...sorta like my earlier pusher design inverted...no pusher any longer. With 2 x 24 hp it also not exactly weak either.

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    Registered User mstull's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Erkki,

    There are quite a few structural and other advantages to using low aspect ratio wings. But one disadvantage is their lower efficiency. Biplanes also suffer from lower efficiency. Lower efficiency wings will need more power to overcome that inefficiency. You're wanting to use an industrial 4-stoke engine. But those engines are known for their very poor power to weight ratio.

    Don't go by what works on an R/C plane. Most any shape will fly R/C. We used to fly flat wings that didn't even have an airfoil, for example.

    I see you are in France. Hopefully your ultralight regulations are different from ours here in the USA. I don't want to say your goals are impossible to achieve, but they work against each other.

    To lift a heavy pilot (and engine) with a low power engine, you'll need long efficient wings. And long efficient wings tend to be heavier and harder to build... and are not small.

    My suggestion would be for you to consider a weight shift trike. At least it folds up small.
    Mark E. Stull
    mstull@wtxs.net

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    Registered User bmcj's Avatar
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    Re: Smallest possible ultralight for real men 230lbs

    Quote Originally Posted by erkki67 View Post
    my runway, if I can call it that way, is 200m (650') long on a slight downhill slope.
    That's only half the story. Does it have an approach (or departure) path clear of obstacles and rising terrain?
    Last edited by bmcj; August 15th, 2011 at 11:08 AM.

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