Thoughts on a new biplane design?

Discussion in 'Hangar Flying' started by cluttonfred, Sep 3, 2018.

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  1. Mar 11, 2019 #101

    Himat

    Himat

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    Ok, both a 450kg and 600kg max take-off weight requirement I do understand as that is the European two seat microlight and LSA regulatory limits. A sport pilot licence weight limit I understand too. A price point is another as I see valid requirement. Still, buying second hand negate part of this.

    But an installed horsepower requirement? Yes, for a part 103 flying vehicle, but less that I do not know about some regulation on installed power. Neither do I know of a country that taxes airplanes by the engine size. Then, why a horsepower limit?
     
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  2. Mar 11, 2019 #102

    cluttonfred

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    In Europe I know the French microlight category better than others, and there the limits for Class 3 (multi-axis) are 60 kW (80 hp) single-seat, 75 kW (100 hp) two-seat. I chose the lower of the two because Rotax four-strokes dominate this engine segment and the 80 hp 912 is the cheapest by far.
     
  3. Mar 12, 2019 #103

    TFF

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    The two place biplane with 60-80 hp is really an almost impossible plane to build in traditional materials. At best you would end up with a plane with 10-15 mph speed range of stall to top, wind would make it hover, and the cockpit would be so narrow people would think it’s a single seater anyway. People have forced these parameters and essentially built throw away airplanes. That are not good airplanes. Some composite dream ship maybe. At best you are building a fat guy single seater.
     
  4. Mar 12, 2019 #104

    Toobuilder

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    Even if through some kind of alternate reality you manage to build a 2 place airplane "substantially" lighter than a Cub (good luck), you still have the high drag Biplane configuration to deal with. The term "sporty" will apply only in the context of trying to outclimb gently rising terrain or landing with more than a breath of crosswind.
     
  5. Mar 12, 2019 #105

    Chilton

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    Being fair to the requirements given, the early moth series aircraft had 60 horsepower, the Hawker Cygnet and others of the Lympne trials 2 seat competition even less than that.

    I doubt the result of the limits here would challenge a pitts but as a putt about 2 seater it should work ok and have acceptable performance for this weight class.

    Care and attention in the design to keep weight down with acceptable strength will be important and the easy build tricks like tube spars would likely be unacceptably heavy for the strength. As many here have said before doing this will require starting from the beginning with a full definition of the requirements in the same way Topaz has shown in his motorglider thread.
     

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