Issues and Solutions for kit- and plans-based sailplanes and motorgliders

Discussion in 'Soaring' started by TerryM76, Sep 3, 2019.

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  1. Sep 5, 2019 #101

    Topaz

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    My personal impression is that self-launching sailplanes are slowly becoming accepted by the "pure" sailplane community as a "necessary evil," given the realities of finding aero-tows and winch-launches in the USA. Once you get into touring motorgliders, which have the ability to cruise cross-country under power, the attitude changes to, "Oh. You're one of them." If there were enough people flying all the types, they'd probably shake out into two separate groups on their own. Unfortunately, I don't think there's a "critical mass" of motorgliders to really develop their own sense of community. They end up "scabbed on" to the "pure soaring" community, and roundly ignored for the most part. If a bridge could be built to the regular power-plane community, that might be a better fit. That's a matter of educating power pilots that turning off the motor is not tantamount to suicide. ;)
     
  2. Sep 5, 2019 #102

    mm4440

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    https://www.motorgliders.org
    Stemmes are both touring motor gliders and high performance sailplanes. I've had two flights and if I win a BIG lotto prize, I would get one.
    So, high on my paper airplane list is a poor person's home built version.
    A single place is a more realistic project. I favor the simplicity of a fixed engine with a feathering or folding prop.
    Without low cost and widely available launching methods pure sailplanes have a limited future.
     
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  3. Sep 5, 2019 #103

    BBerson

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    There was a self-launching sailplane division of SSA. That would be the most expensive category of all.
    I don't know if that group is still around.
     
  4. Sep 5, 2019 #104

    Topaz

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    I think a modernized AS-K14 is probably the answer here. It's what I want for myself, at least.
     
  5. Sep 5, 2019 #105

    BBerson

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    There was an ASK-14 and a RF-4 based at the airport a mile from my house at age 15 in Alaska. We lived under the traffic pattern.
     
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  6. Sep 5, 2019 #106

    mm4440

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    https://sites.google.com/site/motorgliders/Home
    A nose mounted engine is the simplest and lightest engine installation. It is possibly a bit more drag than a pod and boom pusher and you have to look at a prop. Feathering props are not inexpensive. Both tractor and pusher tailed configurations can use flapped airfoils to reduce wing area required and hopefully, weight. VSA can fit on a much more compact trailer and would be a somewhat shorter build. It is unusual and that would limit its appeal which is not relevant for a glider for me.
     
  7. Sep 6, 2019 #107

    BBerson

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  8. Sep 6, 2019 #108

    Topaz

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    Optimizing the wing-pod flow interaction on a pod-and-boom pusher can be a remarkably challenging task, significantly harder than a "conventional" wing-fuselage junction. Our own Jay Kempf here on HBA has done some very interesting work in that area. I know it's more than I can accomplish on my own.
     
  9. Sep 6, 2019 #109

    Hot Wings

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    The unusual has the advantage of being noticed!
    Hopefully if we can get some of these thing built and in the air when people see how much fun we are having, because they noticed the unusual, we can add them to our group.
     
  10. Sep 6, 2019 #110

    Dana

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    Doesn't that just add to the elitism?

    Even within motorgliders, there is difference of purpose. There are motorgliders that are really just efficient powered aircraft requiring no medical, and their owners fly them as such, and there are those that are serious soaring machines and (like a friend of mine who is seriously pursuing badges in his Stemme) whose owners treat them that way.

    The US Hang Gliding Association (USHGA) went through a kerfuffle some years back on how (or whether) to include paragliders. Declining numbers of rigid hang gliders settled that, it's now the US Hang Gliding and Paragliding Association (USHPA). Then there was the "powered harness" debate...
     
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  11. Sep 6, 2019 #111

    BoKu

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    Ooh, it's the SWIFT (Swept Wing with Inboard Flaps for Trim) or its successor the Millennium. Originally designed by a team headed by Ilan Kroo and featuring my friend Steve Smith. My suspicion is that this general configuration and planform is the most likely to achieve the cost and utility targets being tossed around in this thread. Several of these have been motorized.

    The prototype was made with moldless foam core using Kevlar over some sort of styrene foam.
     
    Last edited: Sep 6, 2019
  12. Sep 6, 2019 #112

    BBerson

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    Well yes, but not much solution is possible. Elitism mostly refers to the snob attitude from the high dollar, high performance group or competition specialist.
    But another group just look down on "un-pure" motorgliders.
    That's why so many groups and divisions (even just divisions of motorgliders). My current design is a class of it's own and may be only suitable for me. As you point out, even hang glider groups deal with various classes and opinions.
     
  13. Sep 6, 2019 #113

    BJC

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    All of this discussion isn’t about hardware; it is about people, and the “elitist attitude problem” exists in all aspects of human endeavor. Neither a new design nor a cheaper airplane will change it.

    Sad.


    BJC
     
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  14. Sep 6, 2019 #114

    Jay Kempf

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    40(+):1
    Cruise capable, no retractable motors, no 2 stroke restrictions like climb only)
    Fuel injected 750-1000 cc turbo around 100hp at FL10
    Cruise speed as fast as is possible (probably 150mph practical limit without active damping) faster than most cheap used GA aircraft...
    Two place
    15-17 meters span
    at least 500 lbs useful load.
    CNC direct to female foam one off molds (or a small group commitment to full molds)
    Taxi without dragging a wing tip
    4 hours endurance on 100LL, heavy fuel, and/or autogas
    Trailerable and riggable solo (with a wheeled wing stand is fine) Auto connecting controls.
    Rigging pins with second safety catches, no bolts that can be finger tighted and forgotten.

    That's a worthy goal. Too complex, expensive, large for Topaz.

    Everything to make this work already exists and there are examples of almost every single part and assembly it would take to make it work.

    The hard part is what do you do to eliminate cooling drag during soaring without a huge penalty. Tight fitting retractable radiator ducts probably. Louvers that open with a cooling fan in a turbulent part of the fuselage maybe.

    Weight fractions work, construction methods already exist, span or wing loading works as long as you don't want a 40 MPH min thermalling speed and why would you because you have a motor. Motors and folding/feathering props have been done. There are already canopies out there that can be co-opted.
     
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  15. Sep 6, 2019 #115

    mm4440

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  16. Sep 6, 2019 #116

    mm4440

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  17. Sep 6, 2019 #117

    rdj

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    Absolutely. I downloaded the master FAA database and did some quick searches for words like "MOTORGLIDER" (8 Europa Motor gliders), "XENOS" (22 hits), and the like. Compare that to 1113 hits for "RV-6", 498 for "RV-10", etc. Even searches for "GLIDER" (373 hits) pale next to "RV-" (6358 hits). (Don't quote my numbers; I'm just using 'grep <string> | wc -l' for a crude search.)

    There's no question there's no production market here, which is precisely why Van's has never kitted an RV-11.

    I agree entirely with the statement "I believe we need to build/produce what we want for our own self gratification." That's what I believe as well. It's also why I believe a 'joint project' won't work--there's just too much variability in the personal mission statements. It's a long, lonely road, which is why we don't see more planes of this type flying around.
     
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  18. Sep 6, 2019 #118

    BoKu

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    Call Greg up and ask the price. Actually, just ask how many digits there are in the price.

    Last I heard, it was about 3/16 of the way to two commas.
     
  19. Sep 6, 2019 #119

    mm4440

    mm4440

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    Hi Bob,I tried to get in touch with Greg for an update without success. I hope his business is going ok.
    Consider a poor person''s Stemme alternative a challenge'. Can you produce a kit that comes close to Jays requirements for less than $5000 more than an HP-24 kit, no engine, instruments, or paint; a complete airframe kit? I have some ideas on landing gear and power train that might be useful.
    M
     
  20. Sep 6, 2019 #120

    proppastie

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    Buy an HP-24 kit...change the gear. ..add an engine.....
     

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