Recent content by hstearnsjr

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    Scorpion II rebuild project

    Thanks! It's amazing you'd know that. I guess they're out of business :-(.
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    thrust bearings

    My Scorpion I had a radial needle bearing about 2.5 inches dia and an axial needle bearing 1/2 inch ID as I recall.
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    old cable style rotorheads

    Well, he never said that to me, and I knew him fairly well, we've flown together before, both of us with the cable collective head. Those comments must have come after that period (Scorpion 1). He did ask me to install a thicker cable once. I don't recall ever having to grease the thrust...
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    old cable style rotorheads

    Hey, that's me! (the picture is a 35mm slide) I thought the rotor head was great, no problems at all and the easiest and most stable of any helicopters I've tried -- almost hands off. It is very clever to decouple the collective from the cyclic completely with the added advantage that the...
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    If you lose your tail...

    If you're moving forward fast enough, the drag of the tail will let you fly to your destination (with some yaw), then auto in.
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    Electric tip propelled helicopter AHS presentation by Hoyt Stearns

    Hi Dave, You probably know more than I do about this, but my interpretation is that it's the change of momentum of the air through the fans that determines thrust, not the absolute speed. The thrust curve of a jet engine is almost constant regardless of speed and altitude. The problem I see...
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    Mosquito air helicopter -- Hoyt Stearns Scottsdale Arizona US

    Let me elaborate a bit. My Mosquito Air has carbon composite struts and tail boom and fiberglass legs. I painted them aluminum to keep them from getting too hot in the Arizona sun. The enclosed version of the Mosquito has a fiberglass canopy and structure and weighs about 60 lb. more. I'd...
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    Mini Turbines should light a fire

    Tip jet thrust Tip jet thrust The required thrust is easy -- you get 1 horsepower per pound of thrust with a tip speed of 550 feet/second, so a total of 90 hp is way more than enough. If you mount the engines in line with the spar, you'd pick the direction of the gyroscopic couple to be...
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    More Bruno Nagler pressure jet helicopter historical photos etc.

    Yes, but it was a long time ago. I think he might appear in some of the photos. What's he doing now?
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    Suppliers of thin wall aluminum fuel tanks

    Hi, My original Scorpion helicopter had a 5 gallon aluminum cylindrical fuel tank with very thin walls. My new Mosquito helicopter has similar tanks but the aluminum thickness is much more. Where can I get thin walled 2.5 gallon fuel tanks, preferrably with flush mounted fittings on both...
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    Some pictures of Bruno Nagler and his pressure jet helicopter, etc.

    That was mine. It was a very nice flying machine, but the belts and chains made it a maintenance nightmare. Hoyt Stearns Scottsdale, Arizona US
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    My personal Mosquito ultralight helicopter project website

    Yes, that was close. I am a bit rusty. I'm glad I had the roll bar on. The center of gravity was too far back. I'm fixing that. I thought it felt pretty good the last time I tried it. Remember this is the initial breakin of a brand new helicopter and some adjustments are done after each...
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    My personal Mosquito ultralight helicopter project website

    Thanks for the suggestion, however things are much farther away than they appear in the videos (telephoto lenses do that) (hundreds of feet). I have more than 30 hours of instruction and a more than 100 hours in helicopters.
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    My personal Mosquito ultralight helicopter project website

    I'm posting publically my progress in building and flying my Mosquito ultralight helicopter, including (sometimes embarassing) videos of my practice flights. I have a total of about 1.6 hours on it now. The website will be updated as I fly more.
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    Scorpion chopper

    Scorpion Scorpion Hi, I owned a Scorpion which B.J. Schramm helped me build. It used an Evinrude 100 HP engine. They tried a Mercury engine, but they just wouldn't last, blew rods etc. It worked well. Now I'm building a Mosquito ( ) See...