Todhunter Blue Wren motorglider

Discussion in 'Soaring' started by BBerson, Mar 19, 2019.

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  1. Mar 19, 2019 #1

    BBerson

    BBerson

    BBerson

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  2. Mar 19, 2019 #2

    Victor Bravo

    Victor Bravo

    Victor Bravo

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    I also seem to remember the name Reg Todhunter associated with a two seat Backstrom Plank. Anyone else remember this?
     
  3. Mar 19, 2019 #3

    Topaz

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    Same general configuration as the Ogar, and not far off the Strojnik S-2 (which was mid-wing, but otherwise the same). From the stand point of light, relatively simple construction, yep, it's pretty hard to beat this sort of arrangement. Engine mounting is easy, there's space for fuel (and your lunch or your jacket) below the engine and behind the seat, and it lends itself to super-simple semi-submerged monowheel main landing gear.

    The downside is that, unless you're very careful about shaping in the area of the engine/aft fuselage/wing root, there's potential for simply massive flow separation in the area, engine on or engine off. Ogar's performance compared to other motorgliders of similar span is somewhat disappointing. Performance under power isn't particularly spectacular either, even when taking the small engine into account. The S-2 was probably the best-performing glider of this configuration, but performance under power was underwhelming also.

    For self-launching gliders, the nose-mounted Front Electric Sustainer is probably the best overall compromise, IMHO. Despite the name, a lot of these can take off under their own power, although it drains down the battery pack pretty well. Either more batteries or a small "recharge" ICE fixes that. If the goal is a "touring" motorglider, then a traditional tractor monoplane is probably the easiest and most-efficient, for all the same reasons they are for regular power planes, and certainly no worse for drag than the "average" pod-and-boom pusher.
     
  4. Mar 19, 2019 #4

    BBerson

    BBerson

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    All true. But I am not so concerned about performance, since the launch is almost free. My experience is the better glider type view in front, the skid bottom for field landings and the unique look is important to me.
    I am concerned about wing interference, but I think a narrow single seat body might not fair poorly like Eugene's two seater.
    Any pusher design references? All I find online is this: http://www.angelfire.com/ks2/janowski/other_aircraft/AG14/AER.html

    I plan to go low wing, instead of the Strojnic/Todhunter configuration. More like the Taylor Coot with low wing and swooped up tail boom. Coot seems to perform well: https://en.m.wikipedia.org/wiki/Taylor_Coot#/media/File:Coot_Amphibian.JPG
     
  5. Mar 19, 2019 #5

    Topaz

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    A dirt-simple little "fun" motorglider for local self-launch soaring, yes? This sort of thing ought to be really good for that, then.

    Sorry, nothing "pusher specific," no. The one you link covers a lot of the basics, albeit from the perspective of the twin-boom AG-14. Orion used to have some interesting "overview" material on his website, but that's long since been taken down. One thing that I don't think the AG-14 link you provided covers - or I missed in scanning it quickly - is that pushers tend to be a little longer and heavier overall than an otherwise equivalent conventional tractor design. The latter benefits from having the very compact and heavy engine stuffed right out in the extreme nose, whereas the CG of the pilot rests at his hips, and there has to be a long-ish nose forward of that to accommodate his legs, and the engine is behind him. To get the same tail moment arm, the pusher ends up being a little longer and therefore heavier. Not necessarily a problem unless you're really cramped for storage and/or trailering space, but something of which to be aware going in. I'd say the "penalty" for the kind of airplane of which we're speaking would be in the 24-36" range, overall.

    Sort of like the Cumulus, only enclosed?
     
  6. Mar 19, 2019 #6

    Victor Bravo

    Victor Bravo

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    Janowski J6 Fregata checks a lot of the boxes for me as far as a motorglider, and has the potential for lower (or more manageable) wing junction interference. Since you just mentioned low wing...

    10570.jpg
     
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  7. Mar 19, 2019 #7

    BBerson

    BBerson

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    Could be enclosed or open like the Cumulus. Pushers have less prop blast.
    I would go with 1-26 type wheel and skid and canopy, not taildragger like Cumulus.
    1-26 gear requires a swooped up tail for rotation.
    And I want much lower span. More airplane/glider than glider. (like RF-3, but half weight)

    Janowski was on the right track.
     
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  8. Mar 19, 2019 #8

    PiperCruisin

    PiperCruisin

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    I like the looks of the Janowski and Cumulus. However, I'm a bit nervous about all the mass behind my head. In a crash, I'd rather have that stuff in front of me. Also, all the disrupted flow to the prop and cooling I find problematic. So, I tend to favor the engines up front as being simpler.

    I also like the Windex 1200C. If I remember right the tooling was for sale a few years back. Should have pounced on it. Might have been a good electric conversion.

    I can't just pick one. I like the following for various reasons Pipistrel Sinus, Pipistrel eTaurus, the Pheonix, Elekta-One, Goshawk, Xenos, ASK-14, GP SE 14 Velo (I don't like turtle-deck deployment, but I think this is a great way to do it), and the Alisport Silent 2 Electro.
     
  9. Mar 19, 2019 #9

    addicted2climbing

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    I have mentioned this before, but with all the vintage sailplanes for sale in the 3K to 5K range it would make sense to just design a motor glider fuselage and reuse the wings and empenage. Or at the very least the wings.
     
  10. Mar 19, 2019 #10

    Topaz

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    For a short-range self-launching motorglider, yes, I agree with you. For a "touring" motorglider, however, that's expected to have not only range but under-power cruising speed, the wing from a vintage sailplane is going to be set up for much lower speeds, and wouldn't work as well in that case.
     
  11. Mar 19, 2019 #11

    addicted2climbing

    addicted2climbing

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    Ka6 still has decent high speed in relation to the Ka8
     
  12. Mar 19, 2019 #12

    BBerson

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    Engine mass is only say 50 pounds for a small two stroke, or 130 for a severely lightened VW. I don't see a problem bolting down such a small mass. A 220 pound guy in the back seat of a Cub is way (weigh?) more.
    I am thinking the look of Icon is most popular. But in a single seat version.
     
  13. Mar 20, 2019 #13

    Victor Bravo

    Victor Bravo

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    Alpaero Exel, another superb example of the type of aircraft being discussed:

    exel33.jpg
     
  14. Mar 20, 2019 #14

    BJC

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    I wish that the J6 were available. I like the concept, and would love to learn more about it, and potentially own one with a reliable engine.

    Janowski had several previous designs, including the J5, which I like in spite of the fact that my hangar mate was killed in his J5. http://www.angelfire.com/ks2/janowski/j5.html


    BJC
     
  15. Mar 20, 2019 #15

    Victor Bravo

    Victor Bravo

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    What happened in this accident? Was it an engine issue and a forced landing, or a structural issue with the J5???
     
  16. Mar 20, 2019 #16

    BJC

    BJC

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    AFAIK, there was no formal cause determination. Those of us who knew the pilot and the airplane believe that the pilot’s habit of flying with the kit documentation on the cockpit floor led to jammed / damaged flaperon deflection on final, causing the airplane to spin onto a roof top just off the end of the runway. The crash looked survivable, but the pilot perished.


    BJC

    edit: NTSB report here: https://ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001212X24498&key=1
     
  17. Mar 20, 2019 #17

    BBerson

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