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  1. #1

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    Please Help With Piano-wire Landing Gear

    Hi Everybody! Happy New Year!!
    I'm in the middle of a project I want to do something special for. I know this airplane (a 1960s Delta Huslter with a new Jett 35 FIRE) was originally flown with non-retractable landing gear. So, the wheels were always sticking out from under the plane. Today I think that's weird. Plus - it'll slow the plane a lot!!

    So, I have a desire to finish building this plane with a set of ( 3 ) retractable (through very narrow slits) piano wire landing skids. Have any of you guys seen or heard of this before? Has it been done on RCU before? Or anywhere else you know of?

    My idea is to use one servo to extend and retract all three curved piano wires through narrow slits on the bottom of the delta shapped wing. I'm planning to always hand-launch the plane, but want to help protect the undercarriage by being able to extend thick (eventually replaceable) piano wires (curved aft) just before landing. The wires don't have to extend a long distance - maybe an inch or two. plus I think it'll look really cool!!

    One final "other idea" or "question" about the landing-wire mechanism; "...do you think I'll need to include, in the design, some kind of spring setup to help protect the servo?" ...or will the aft-curved piano wire BE spring enough? I'm hoping this little bird will reach somewhere around 150 mph...

    OK, now I look to you .. .. .. .. .. any Ideas? Thanks!! Mikie

  2. #2
    combatpigg's Avatar
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    RE: Please Help With Piano-wire Landing Gear

    20 years ago I built a delta in this size range that I hoped would be real fast with a piped Webra .50. It had fixed gear with lots of weight devoted to hardwood LG blocks and reenforced ribs...typical fixed gear carpentry for .40 sized planes. This plane was a dog, so I removed the LG..but left the inner hardwood LG attachment lumber in the plane.
    Still a dog. So I cut open the plane and removed the unused LG hardwood and anything else that looked like "over kill" in the structure.
    Still a dog. I wrote the whole experience off to having a plane that was still a little bit too thick and heavy. Building a much sleeker and lighter Diamond Dust really opened my eyes 10 years later as to how you make a delta in this size range a fast plane.
    WHO GUNNA FEED MAW KEEEIDS..???

  3. #3

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    RE: Please Help With Piano-wire Landing Gear

    Well Mikie, That's a nice delta project. I'm going to agree with combatpigg on on weight being your enemy. You could do it, but to keep the weight down would take a lot of engineering and I don't know it the results would be worth the effort. First off, that delta has a large cross section, and it'll take a BIG engine to get that to 150, we're talking about a heli 90 size. At the speed range the your plane is capable of (85-ish) with the 35, the drag of the landing gear isn't the main issue, perhaps more aesthetics. If it were me, I'd go with the landing gear, but I'd make it more slippery. I'd use some pylon racing wheels by drilling out the brass bushing to fit your gear and use a collar to keep it on. http://shop.sam-rairacing.com/Stream...ls-SRW-225.htm You can also put a tapered trailing edge on the landing gear with strip of balsa. Use Shoe goop because it flexes. Then cover with white covering or tape to make it disappear.

    If you are intent on wire retracts, use "retract" servos and position the arm on the servo is rotated in line with the linkage when gear is extended. Also, the point at which the mains contact the ground should be just aft of the C.G. That way when they make contact at landing, the plane does not rotate too hard onto the nose. Suggested music wire size, mains .078" nose .125". Works great for fixed wire landing gear on a Diamond dust.

    Hope this helps.
    Oooh eee oooh ah ah(the crowd) ting tang walla walla bing bang!(the plane crash)

  4. #4
    MJD's Avatar
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    RE: Please Help With Piano-wire Landing Gear

    The Hustler has a fat old wing profile with reflex, as a delta "full stunt" design (whatever that means) rather than a speed design. I would expect a Jett .35 to be capable of perhaps 140(?) in a thin wing contemporary delta. But in this guy I think you need to settle for "brisk" performance but not fast. FF's estimate of 85mph might be right on. I'd stick with the 9-6 prop you've been running on that engine, likely spot on for this aircraft. I doubt smaller/higher pitch will buy you much if anything.

    In the early '90's I saw a Top Flite Holy Smoke, fitted with a piped YS .60 rear exhaust. It has a retractable nose wheel, and two fixed wire tip skids. Take off roll was blasting the throttle and taking off whatever direction it was pointed. I can only estimate the speed from memory, but I would say that while it was fast, it was likely no more than, I dunno, 140mph?

    What about 3 small fixed wire skids? You could make them removable. I've pondered using a single recessed pylon racing wheel in the nose (half of it hanging out) and two wire skids outboard on the CG as something like you are doing but not retractable.

    But the retractable skids would look cool, so really that's a good enough reason to do it right there. Go for it!
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  5. #5

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    RE: Please Help With Piano-wire Landing Gear

    When I do my wire skids I use a thin wire half circle loop at the the wing tips. You dont need 5/32 wire lol if you loop from leading edge to he tip and secure it at the ends. Fot the nose skid again a small loop of 1/16th or so loop from engine mount to 2-3 " behind the CG. This loop only needs to be about 2" off the bottom of the wing.

    This offers the least drag and weight of any set up if must have skids.
    AMA # 126183
    Fly light, fly fast and fly low.


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