Please criticize my microlight multiengine design

Discussion in 'The light stuff area' started by Xanadrone, Apr 20, 2013.

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  1. Nov 25, 2013 #41

    PTAirco

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    I like small, minimalist airplanes designs, but you keep referring to your designs as "microlights". Unless Romania has some very different rules, none of these designs would fit into any microlight category I know of - way too little wing area/too high a wing loading. "Microlights" or whatever they coose to call these types of aircraft in most European countries are limited to wing loading of around 5lbs/ft or around that figure. Yours are more like 8.75 and would never meet these criteria. Still nice design ideas, but firmly outside the "microlight" area. Like the Cri-Cri, which many people refer to as an ultralight or microlight - way too fast and too much wing loading to qualify.
     
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  2. Nov 26, 2013 #42

    autoreply

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    Virtually all of them are around 10 lbs/ft2. Note that he only needs to reach a (3d) Clmax of 2.11, not unrealistic IMHO.
     
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  3. Nov 26, 2013 #43

    Birdman100

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    Xanadron,

    in this all digital era, its nice to see some beautiful hand drawings. Congratulations!
     
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  4. Dec 19, 2013 #44

    Xanadrone

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    Thank you folks for appreciating some drawing skills - not at all enough for a viable design though.
    Unfortunately, I’ve lost the plans partially shown here, moving around a lot lately.
    But, as I wrote some time ago, it’s my turn to be posessed by the micro-hydroplane frenzy.:gig:
    Main reason: I've recently moved to live in the mountains, with a gorgeous lake near-by - and I don't really like (or afford) big, pricey & slow bushplanes - or trust gyrocopters.

    So, more news/plans of a micro-amphibious E/IC hybrid (3-views) coming soon...
    Anyway, my empty-weight target sounds a little bit more realistic (90 kgs or 200 lbs. - without batteries needed only for take-off support.)
    Or, if I’m choosing a… tinyer solution (with a pilot’s prone position), 80 kgs would be maybe achievable - or even 70 kgs as an absolute minimum, using lots of carbon fiber (hard to put in practice though, calculating the high costs involved.)
    I’m far away from the +700K euros sucked from EU-fonds by the creators of the (dubious IMHO) FlyNano - to be more precise, I hope to get by with 100x less :devious: (7K euros or 10K USD).

    P.S. Regarding the romanian regulations, autoreply was spot-on - all it’s required is a 65 km/h demonstrated stall speed (approx. 40 mph). The official approval formalities are also very lax around here for monoplace microlights, if flown only by the designer.
     
  5. Dec 19, 2013 #45

    autoreply

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    Hydroplanes are a bad idea in most countries, simply due to the strict regulations. There are a few pleasent exceptions, but be sure to check your local ones first.

    Carbon is very expensive... per kilogram, not per aircraft. You only need very little of it.
    Say 40 square meters of glass for the wing skin, 15 square meters of carbon for the fuselage and spar plus some UD tape and you're looking at 500 E for the carbon and glass, another 200 for the foam cores and another 250 for some UD tape and epoxy. Add 50% of that cost for consumables (gloves, tape, foil, tables, cutters and on and on) and you're there if you can borrow a vacuum pump.
     
  6. Dec 19, 2013 #46

    topspeed100

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    I am not sure if Flynano folks got 700 k€ from EU...maybe just a local investor fund. It is a lot of money especially with those results they got. My box wing really looked like a box...really simple...and too short to make a good aircraft.
     
  7. Dec 19, 2013 #47

    Xanadrone

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    (1) No special issues around here for hydroplanners :) - the number of them is close to zero and even insurance rates are ridiculously low.
    (2) Good news indeed, 'cause I thought the costs of mixed-composite homebuilding would be way higher (I've been theoretically inclining till now for a glass/spruce/plywood scheme).
    Only borrowing a vacuum-pump could be problematic - sadly to say, but the romanian aero-industry is in coma if not dead already :ermm: despite former traditions (Henri Coanda etc.) and a very small bunch of enthusiasts fly mostly certified western classic ULs, SLAs etc.
    There's btw. only one small producer of light AC left (assembling an old licensed model), whilst Poland or the Czech Republic have 70-80 different manufacturers.
    ...But I'd be eager to know how big would be the resilience-losses for an "old-school" way of laying-up composites? (without a vacuum-pump). Or is it better to go for an artisanal DYI pump?

    P.S. @topspeed100: EU research-funds are sometimes gigantic - not bad in principle, but the big money is sometimes given to politically-backed dudes (I know for example a british motorcycle-steering-system project - EU-subsidized - absorbing a couple of millions 15 year ago. UK pounds, n.b., and without any practical applicability.)
    Cannot pronounce any verdict though about your boxwing-hydro project - the sole image you've posted some time ago is too misteriously dark.;)
     
    Last edited: Dec 19, 2013
  8. Dec 22, 2013 #48

    autoreply

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    I was mostly thinking bout permission to land/TO from rivers, lakes etc.
    A new one runs a few hundred euro's.
    http://shop1.r-g.de/item/390100
    Last layup I measured; we got about 50% of the epoxy out. That's a 50% heavier laminate if not vacuum bagged. That's from experienced people in a complex layup, so if you're inexperienced, expect waaaay more. You're easily down to almost twice the weight.

    Vacuum-bagging IMHO is mandatory if the part is meant to fly.
     
  9. Dec 23, 2013 #49

    Birdman100

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    Typically hand - lamination is around 35% fibers of laminate volume. Vacuum lamination is around 60% fibers. The difference in laminate weight ( "hand" vs "vacuum") is up to 30% for glass laminates and 35% for carbon laminates (that is due to different fiber densities for glass and carbon). There is no point comparing soaked laminate and vacuum - bagged, as you wouldnt apply so much resin if you go with hand-lamination only.

    Up to 40% fiber with hand lamination is doable but highly optimistic. I did 43% on few samples.
     
  10. Dec 23, 2013 #50

    autoreply

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    In my experience you won't even come near most of those values in a real part.

    A reasonable vacuum-bagged part does maybe 40-45% fiber volume fraction, with a good vacuum and gentle curves maybe 50%. Wet, even in glass, I

    Note that the epoxy numbers (on carbon) are for a thoroughly saturated and agressively squeezed laminate already. Even then you have almost 50% excess epoxy. Glass isn't that horrible, neither is kevlar (did a 15m2 layup today with close to a hundreds parts... pretty wasted...)

    Even with vacuum infusion of woven fibers you'll have a very hard time to come even near 60% fiber volume. With biax, Triax and UD though *grin*...
     
  11. Jan 13, 2014 #51

    Xanadrone

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    Just found an older up/down-view of my microlight "speedy" bimotor and it seems that the Hstab volume is not too small (bigger anyway that PIK's Sykty.)
    I'm still working on the micro-hydro-ideea (it takes longer because it's far harder to find the best compromise), but I'm not putting completely aside some "normal AC" configurations.

    This one may seem hazardous with two big 2-stroker RC_engines (for ex., two MVVS 175 cc X 20 HP each or two 3W-275 cc producing 27 HP each = 54 HP - All Engines : 3W-275 XiB2 TS CS : Katalog: 3W Modellmotoren - Modellmotoren und Flugzeuge ), but, speaking from personal experience (with MVVS and ZDZ), a 200 hour TBO without problems in-between is realistic, if the engines are good oiled / jetted / sparked / warmed-up and used more for "scale-flights" than for savage hoverings.:gig:
    There are some advantages of 2-strokers too - the possibility of easy gentleman's aerobatics (v. membrane carbs), the very low engine-weight (2 x 11 lbs for MVVS, 2 x 15.5 lbs for the 3W) or the low price of the props (a good quality 24 x 28 Biela carbon prop is only 60 euros - http://www.smigla.com/ ).
    All - for possibly better performance compared to a less optimal streamlined Cri-Cri (150-170 mph would be reachable for 40-54 HP, despite the weak efficiency of the small propellers - let's say 70% instead of 85.)

    I'll be back soon anyway with some more details - for the amphibious-project this time.
    scan0001.jpg
    Top-001.jpg
    3W_275XI_B2_TS_CS.jpg
     
    Last edited: Jan 13, 2014
  12. Jul 21, 2014 #52

    Xanadrone

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    Well, a late come-back seems better than none, but I’ll try to make it short – I don’t want to be a second topspeed100 with gazillion variants, even if the personal search towards originality with any price might be of interest for some of you (hmm, usually the failure is the price of hyper-nonconformism in HB ;)).

    So, I (re)started last summer with a microlight amphibian idea.
    In the end it was a bad one, after I finally found out that the lake near-by is not allowed for planes, but the calculus/design process was exciting anyway.

    Thus, after drawing a biplane in various guises (V-tail, inverted V-tail, push/puller with combined ICE/EM or bimotor on the upper wing etc. - the drawings attached are only some of the less detailed ones), I decided that a high strutted wing solution woud be the best one (with flaperons and on a central pylon for drag-reduction – the discussions around here are useful indeed) – a hershey-bar wing foldable by simple rotation on its main axis and with twin… small twins ICE/EM propulsion.
    scan0002.jpg scan0001.jpg
     
    Last edited: Jul 21, 2014
  13. Jul 21, 2014 #53

    Xanadrone

    Xanadrone

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    (New post whilst I couldn’t edit properly the previous one):
    Last month I had a little spare time to reset my direction to “only-land operations” - preferrably on the STOL side -, keeping the (stubborn, I agree) idea of the pilot’s prone position.

    None of the two versions satisfied me though in terms of simplicity/efficiency (a non-flapped biplane with two shrouded props, an original suspended front mono-wheel and a bicycle-wheel instead the V-stab and rudder – what would you think about it anyway? - or a low-wing low-AR monoplane with bird-like strakes and V-tail, pulled by two VM210 4-strokers of 16 HP each), so I’m focusing now on a new and even MORE original… let’s name it “convertible ducted-fan and semi-DEP” version.

    Hoping that this will be the final one whilst I'm already old enough to start BUILDING it, I’ll come back with the drawings and tech details this week, ready to get any eventual “punch” I might deserve. :gig:

    scan0003.jpg scan0004.jpg
     
    Last edited: Jul 21, 2014

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