Flying on 14 hp

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by cluttonfred, Jul 13, 2010.

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  1. Mar 21, 2017 #221

    vtul

    vtul

    vtul

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    Well this isn't exactly that wish list, but points the way on most counts, and a fair number were built.

    Skypup:
    Cantilevered 31' wing, 43018 foil, 195 lb empty, 400 max

    20 hp, Cuyuna 215
    fairly lossy 2.25:1 multi-belt redrive
    Prop 58 x 24, 2900 RPM
     
  2. Mar 22, 2017 #222

    blane.c

    blane.c

    blane.c

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    The 5" and 6" tubes are for the tail boom? Or does Kolb use them in the folding wing as well? 60 series aluminum isn't as strong as 2024 0r 70 series but it is more forgiving of vibration I.E. it doesn't crack as easy. The DC-4 had aluminum spars that predated the availability of 2024 and had much less stress cracking than the DC-6 which had the newer alloy.

    My Flyer measures 20 foot long and the tail boom tube is 13 foot 2 inches. It was cut off around three feet from the front end (not measured) and later spliced back together supposedly for ease of shipment. Not that i like the splice one bit but it obviously worked.
     
  3. Mar 22, 2017 #223

    BBerson

    BBerson

    BBerson

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    Both. (boom and wing)
    6063T6 is only about 25 Ksi compression.
    6061T6 --------------35
    2024T4 ------------ 50
    7075T6 -------------- 68
     
  4. Mar 22, 2017 #224

    Dana

    Dana

    Dana

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    6" is stiffer, of course, but there was no problem with 5"... it was the wing root attachment that wasn't stiff enough, allowing the Ultrastar wing to twist. The later models had an improved design there.

    Kolb used the 5" tubes in the earlier / smaller models, 6" in the later / larger ones. Same size tube for the wing spars and tail boom. 2024 is stronger than 6061 in tension and compression, but equal in buckling, which is the likely failure mode, and yes, better in fatigue. Plus, large diameter tubes aren't available in 2024.

    Dana
     
  5. Mar 22, 2017 #225

    BBerson

    BBerson

    BBerson

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    I studied the Kolb wing and not sure it is lightest. It has three tubes, leading edge and trailing edge same as traditional ultralight and also the big tube. I guess the reason is to allow one strut for less drag or folding. A newer model has two struts apparently to hold the main tube rigid in torsion, see photo. The Avid/Kitfox has a simple two spar and two strut and simpler wing folding with gross weights up to 1500lb using 2.5" 065" tubes.

    For 16hp, much lighter wing tubes and internal structure is possible, I think. image.jpg
     
  6. Mar 22, 2017 #226

    Dana

    Dana

    Dana

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    The Kolb's one big tube is really the only actual spar, the other tubes just form leading and trailing edges, unlike, say, a Quicksilver with its ladder frame where the leading and trailing edges are the spars.

    Only the Firefly has two struts and they're not actually required structurally... Kolb only added the second strut to add drag to make the plane 103 legal on paper according to the formulas in the AC103-7 appendix.

    Dana
     

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