Some fun vintage reading, light aircraft - Lympne trials...

Discussion in 'The light stuff area' started by WBNH, Sep 20, 2019.

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  1. Sep 22, 2019 #21

    pictsidhe

    pictsidhe

    pictsidhe

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    If this is for affordable avaition, perhaps we should put a cap on the materials cost. If an expensive process is needed to fabricate, then that should be a disqualifier, too.

    If shooting for LSA, entrants will need to compete with expensive composite wonders such as the A5. That is going to be very difficult for small teams. Other countries have their own botrtom rung of aviation. 103 is adaptable to the majority of them. A designer is of course free to build in extra capability to meet higher foreign performance, then limit it for 103.

    Ideas for key criteria: build cost, running cost, ease of use.
    I'm thinking of something that Average Joe could pull out of his garage on a Sunday, trailer to a nearby field, and fly for a few hours.
    Hmmm, how about one criteria being that it fits folded in a standard garage? Though I may change my mind on that if my project does not ;)
    The judges free vote could be used to weed out impractical point design 'winners'.
     
    Last edited: Sep 22, 2019
  2. Sep 22, 2019 #22

    pictsidhe

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    I see gliders with motors strapped to them winning the electric efficiency class.
     
  3. Sep 22, 2019 #23

    Hephaestus

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    Depends how speed gets weighed in the competition.

    Depends on how you qualify it. In many places composites are cheaper than wood/aluminum because of local sourcing options.

    Build logs would be cool ;)
     
  4. Sep 23, 2019 #24

    jedi

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    Roadable is not that difficult if you go far enough outside the box.

    upload_2019-9-23_0-17-6.jpeg

    Sorry about the up hill trek. Can't get it to keep from autorotating. This is roadable if only a glider. The same can be done with a paraglider motor and several years ago there was a three wheel peddel driven bike with a paraglider motor but it did not make the cut as a viable product and the business closed. It was too slow on the road and in the air and took too long to convert road to flight. Also the layout of the wing on the ground was a handycap. IMHO.

    The above is still roadable without the bicycle but the ground operational radius is much more limited. On the plus side the launch is much easier.

    Desired operational parameters. Up to 25 mph on surface. At least 45 mph crusing speed. 5 mile surface operation radius. 50 mile range airborn. Able to take off or/and land off airport within 5 miles of most locations.

    Cost of a successful product is offset by usefulness. Make it more useful and people will pay more.
     
  5. Sep 23, 2019 #25

    pictsidhe

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    It doesn't matter what materials are used. it matters what it costs.
     
  6. Sep 24, 2019 #26

    bifft

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    Seems to me that 15 minutes from trailer to flight is plenty fast.

    So, if part 103 legal 1000 miles @ 55 kts means 16 hours of flight time in one week. Seems highish but doable.

    Aside from the electric thing my 103 napkin sketch would qualify (assuming I could actually build it to the napkin specs). No way I could have it flying by 2023 and still keep a full time job. Do like the idea.
     
  7. Sep 24, 2019 #27

    pictsidhe

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    I was thinking 3-4 hours a day would get slowish 103s through the distance. This will determine reliability. It's supposed to be a trial! No reason to insist on the same pilot for all the flying. It's the aircraft that are being evaluated. But for the slower aircraft, 30 hours could be an alternative? Electrics probably need a lower target.
     
    Last edited: Sep 24, 2019
  8. Sep 24, 2019 #28

    Hephaestus

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    Well EADS efan is a 100mph cruise, with 1hour flight times... Use a pair of those J1772 chargers like you see all over the cities now - 240v 20amps each... you could do a few hops a day...

    Pipistrel alpha electro is 45 min charge for an hour's flight (20mph faster)

    There's no real reason to lower the bar, the push is to raise it isn't it?
     
  9. Sep 24, 2019 #29

    pictsidhe

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    Hammering batteries all day could give temperature problems. They get warm in use, and warm while charging. Unless we are aiming at having all day electrics, it seems a little unfair to insist on that flight regime. For Hobby use, people probably aren't going to do more than one charge between flights per day, while they eat their $100 hamburger. With electrics being a nascent technology, just having affordable and usable ecraft seems a good first target. Perhaps 5 or 6 hamburger runs over a week could be the target for the ecraft?

    If I hammer my Li-ion cordless tools, I have to play musical batteries as heat will stop me charging them. 2 batteries is not enough for continous work! Yes, cooling could be improved for aircraft, but that's more weight and drag on something that really doesn't want extra weight and drag.
     
  10. Sep 24, 2019 #30

    Hot Wings

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    My personal limit for assembly is under 5 minutes for a part 103 like plane. Solo assembly is a good goal as well. Automatic control hookup should be mandatory.

    << >>
    Depends on the wind direction. ;) 55 into my areas seemingly constant 20 won't get you very far.

    Don't forget hybrid! A clean speed limited part 103 is an ideal platform for such a power system. Fly all day on a 5 hp ICE while recharging the battery for the next climb.
     
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  11. Sep 25, 2019 #31

    pictsidhe

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    Wow, some people are impatient!
    I'd like solo assembly too.

    I'm failing to think of a reason why hybrids shouldn't be allowed in the gas class. 5hp is kinda low. Propastie may have something that could hit that target.
    My own 103 project will feature a CAS triggered power limit. Below 55kts, there is no power limit. 55+, it will have appendix power. This is legal.
     
  12. Sep 25, 2019 #32

    Hephaestus

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    I like the 1926 rules. Throw a weight limit on the total weight of the power system (including fuel/batteries), and you can do as you see fit.
     
  13. Sep 25, 2019 #33

    pictsidhe

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    254lbs for the whole plane should work quite well.
     
  14. Sep 25, 2019 #34

    Hephaestus

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    But only the USA has that part 103 rule, the rest of the world uses basically what you'd call a LSA as ultralight/microlight.

    The 103 standard makes little sense, makes for weak structures and wouldn't allow any real development or margin for safety.
     
  15. Sep 25, 2019 #35

    Hot Wings

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    Not impatient, just a realist. 5 minutes is about all we get around here between gusts to assemble a light plane solo. :rolleyes:
     
  16. Sep 25, 2019 #36

    BBerson

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    I think the English Electric Wren that won* the main event was at ultralight weight, around 250 pounds.
    The DH-53 was 310 pounds.
    Should be in that range for field landings.

    * there was a tie for first. I think the other was A.N.A.C or something.
     
  17. Sep 25, 2019 #37

    pictsidhe

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    The Wren is not very practical. My favourite was the Cygnet, which has passenger access difficulty. A single seat Cygnet would be great.
    Most of the decent entrants had 103-ish specs.
     
  18. Sep 25, 2019 #38

    BBerson

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    The DH-53 was considered the most practical. Even did aerobatics and a dozen or more were sold. Was not frail like the Wren. My DH-53 could be under 254 pounds, the original was 310.
    A true replay of Lympne would be with replicas as much as possible.
     
  19. Sep 25, 2019 #39

    pictsidhe

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    100 years on, without using fully moulded laminar carbon composites, we probably won't be beating the originals by much. So I say lets go new and cap the cost.
    Some of us are waiting for your DH-53. When the Shuttleworth one is rebuilt, I'll get you some photos.
     
  20. Sep 25, 2019 #40

    BBerson

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    My DH-53 is a standoff scale made with aluminum, slightly smaller and should weigh about 230, I think. I have the fuselage built. The DH-53 replica was a transition design while I tried to engineer the ultimate ultralight cantilever wing structure. Think I have that now, so building a new design*. The DH-53 is back burnered for now.

    *details not to be released until finished
     

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