stunthanger.com
General control line discussion => Open Forum => Topic started by: Matt Piatkowski on June 28, 2022, 02:27:23 PM
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Hello,
Imagine Leonidov's La-4e, RTF weight=1830 grams (64.55 oz.), standing on a hard surface of a circle.
The main gear struts and the foam of the main landing gear wheels (2.25 " dia) deflect a certain amount.
Most of this deflection comes from the deflection of ultra-light wheels.
The tail landing gear also deflects, but most of this deflection comes from bending the steel wire that constitutes the tail landing gear strut.
When the model stands on the ground and is ready to be launched, both deflections mentioned above produce the wings AOA about 4 degrees.
When the motor starts and the model accelerates, the tail gear strut gradually straightens, maintaining contact with the hard surface of the circle for about 15-20 feet. Then, if I do it right, all wheels leave the hard surface, and the model gradually climbs to the horizontal flight at 1.50-1.80 m. above the ground.
Should the tail gear wire be softer or stiffer? With stiffer wire, the model sits on the ground at 2 degrees AOA and rolls ~30 feet before taking off.
Please note that the length of the tail wire is the same - only the bending flexibility differs.
Regards,
M
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Matt, I don't think you have explained what is it that you don't like about the tail gear and/or the resulting takeoff, and what is it you are trying to achieve.
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Is this a joke or something? The flexibility of the tail wheel wire??
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Is this a joke or something? The flexibility of the tail wheel wire??
If you fly competitively, no, not a joke at all.
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I learned about the long wheel and the arguments against it flying with Bob G. and the "Purist" back in the 70's. Been using one ever since. Interesting that I have had 2, that I can remember, prop strikes at contests and both times it was when someone outside our flying group was launching. Never gave that any thought. Thanks Bob for the technical answer!
Ken
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The downside to a long and flexible tailwheel wire is the possibility that your helper when launching the plane may compress the tailwheel wire too much and when the model is released the compression rebound of the wire causes the tail to spring upward... and the prop downward! Lots of chipped props have been the result from this over the years. I always caution my helpers to not compress the tailwheel wire when launching.
That's one reason I'm not allowed to launch Varsity airplanes.
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But, you're allowed to fly them... Weird! n~
Bob
You are just yanking Howard’s chain, but a lot of people don’t realize that launching them in any significant wind is much harder than flying them, and much more risky.
Brett