Has anyone be thinking of designing a more modern, light weight powered sailplane ?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Pops, Nov 11, 2019 at 12:26 AM.

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  1. Nov 11, 2019 at 12:26 AM #1

    Pops

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    Has anyone been thinking of designing a more modern wood , light weight powered sailplane similar to the Fournier RF-3 ? Lighter EW with a lot of carbon fiber parts , but main structure wood. Also powered by a 1200cc to 1835cc light weight VW engine, ( 40 to 60 HP). I have been thinking about it for a couple years.
    Any ideas ?


    https://en.wikipedia.org/wiki/Fournier_RF-3

    http://all-aero.com/index.php/contactus/60-gliders/3960-fournier-rf-3

    http://www.club-fournier.de/dev/wp-content/uploads/2013/02/Testbericht-RF4D-1968-07-01-AOPA.pdf
     
    Last edited: Nov 11, 2019 at 12:52 AM
  2. Nov 11, 2019 at 12:40 AM #2

    BBerson

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    I am building one now. All metal and fabric. Engine from 670cc to 1600cc.
    That's about all I am saying till it's finished. :cool:
     
  3. Nov 11, 2019 at 12:55 AM #3

    Pops

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    Now, you are going to make me lose sleep thinking about what you will not tell us. :)

    Wish you all the best.
     
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  4. Nov 11, 2019 at 1:16 AM #4

    Aerowerx

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    Heard a rumor that some guy on HBA, user name "Pops" was thinking about it.;)
     
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  5. Nov 11, 2019 at 1:39 AM #5

    Pops

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    All that guy does is dream. Don't pay him any attention.
     
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  6. Nov 11, 2019 at 1:52 AM #6

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    I think about it quite a bit.
    https://www.homebuiltairplanes.com/forums/threads/robin-ultralight.9249/

    Looks like it is taking a back seat to Wren 2.0
    http://robinultralight.blogspot.com/
     
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  7. Nov 11, 2019 at 2:42 AM #7

    Aerowerx

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    I would guess that the early Janowski designs could be considered that, the J-2 more than the J-1B.

    They were intended to be transition trainers for glider pilots wanting to get into powered flight. The J-2, in particular, had a single wheel with rollers on the wing tips (low wing design).
     
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  8. Nov 11, 2019 at 2:52 AM #8

    bifft

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    I've been thinking of something similar, but with electric motor instead of gas. Intended to glide locally and just go cross country on the trailer.
     
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  9. Nov 11, 2019 at 2:58 AM #9

    Aerowerx

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    As a side question, has anyone considered an electric motor glider with solar power assist, to keep the batteries topped off when motor power is off?
     
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  10. Nov 11, 2019 at 3:21 AM #10

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    Bob Barrows, the designer of the 4 seat Bearhawk, Bearhawk Patrol, Bearhawk LSA is designing and building an ultralight electric that looks like a scaled down Bearhawk LSA powered sailplane.

    My FIsher Koala 202 plans shows a 30' wingspan model and a 36' wingspan model. The 30' span has 120 sq' of wing area and the 36' span has 144 sq' of wing area.
     
  11. Nov 11, 2019 at 6:11 AM #11

    Victor Bravo

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    The Janowski J-6 motorglider and the Alpaero Excel loook pretty good for this use, although they are pushers.
     
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  12. Nov 11, 2019 at 6:52 AM #12

    TiPi

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    At approx 200W per m2 of surface in full sun, it is probably not worth the extra weight and complexity for a "normal" aircraft.
     
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  13. Nov 11, 2019 at 11:09 AM #13

    plncraze

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    I look forward to seeing what Barrows' does with what is available. There are a lot of smart folks messing with this stuff and hopefully it will get more affordable.
     
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  14. Nov 11, 2019 at 1:50 PM #14

    mcrae0104

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    Which parts do you imagine might be good candidates for CF? Maybe the spar and D tube? Would you keep the wood ribs and fabric aft of the spar?
     
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  15. Nov 11, 2019 at 1:58 PM #15

    mullacharjak

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    The German EEL ULF2 is within a few inches of the RF3 but I think it doesnt fit the requirements as its already designed and it doesnt have any carbon parts or a vw and fixed gear !
     
    Last edited: Nov 11, 2019 at 2:04 PM
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  16. Nov 11, 2019 at 2:06 PM #16

    Aerowerx

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    Maybe, but I was not talking about running the motors, but to put some charge back in the batteries when soaring with power off. Even 1 or 2 amps for a half hour would help, I think. It could help you get back to the field after all the thermals are gone.
     
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  17. Nov 11, 2019 at 2:17 PM #17

    John.Roo

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    litespeed and Pops like this.
  18. Nov 11, 2019 at 2:17 PM #18

    Pops

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    Had a good talk with Bob Barrows couple days ago about the Electric Ultralight that he is designing and building. He was asking about the JMR since he has been watching the construction since day one. He is now just starting to get back in the workshop and work a little and fly a little after his accident last year. He is building the fuselage with steel tubing and aluminum spars and ribs with CB leading edge in the D tube. Bob is a master in building light weight. I was thinking of a strut braced high wing for lighter weight but sure like the looks of a slick low wing and low drag. Also using CB cowl, boot cowl , door, most non structure parts. Wings and fuselage fabric covered as much as possible. Having built 3 sets of geodetic wings in the past, its a good way to built a very strong light weight wing. Not as labor intensive as it looks. The geodetic strips goes on very quick and easy. For a high AR wing I believe it would work out very good. The first set of geodetic wings on the SSSC weighed 37 lbs each. I built another set of wings with larger fuel tanks. Also made the main spar caps a little larger for the added weight of the increase fuel load. Fuel in the wings helps over having fuel weight in the fuselage. So these wings were slightly heavier than the first wings.
    As a general layout of the design I was thinking more in like with the picture but without the "T" tail. But a taildragger, for the light weight and lower drag and fun.
    Haven't decided, but thinking about a mono-wheel like my old I-26 sailplane.
     

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  19. Nov 11, 2019 at 2:38 PM #19

    Vigilant1

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    It is lighter and much more reliable/flexible to just carry more battery rather than the solar panels needed to make that power.
     
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  20. Nov 11, 2019 at 3:36 PM #20

    BBerson

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    image.png The KR-1B motorglider was much smaller than the RF-3. The Moni was 27', much smaller also, same idea.
     
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