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Originally Posted by jflis
What a hoot! I love a good kit mod and this one is great  |
I know! I wasn't really sure that it would have any kind of actual flight on a Micromaxx-II, but I have been delighted with the flights that it has turned in. They are really something to see, but in a comical way, rather than being impressive.
It's neat to watch the TW really zip upwards for about 10 feet, and then put on the brakes and coast to a dead stop in mid-air, pause for a split second, and then just drop. Like something you would see in a Road Runner/Wile E. Coyote cartoon.
But to get this kind of flight, the launch rod has to be really clean. I found that any residue on the rod will create more drag than the little Micromaxx motor can overcome. Replacing the 1/8" rod with a length of music wire that is just a little bit smaller in diameter, like 0.080" or 0.095", may help, too, but I haven't tried that yet. It also helps to launch it in very still air, with the launch rod pointing straight up.
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Does it actually tumble? I was wondering is there was enough mass in the spent MMX motor casing...
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Yes!! Well, sort of...
First of all, you have to realize that the TW doesn't have very far to fall when you launch it with this motor.
When it starts to drop, aft end first, it will naturally start to somersault anyway. The ejection charge fires late, after the TW has already started to fall, but yes, it does seem to alter the rocket's orientation at that point. The rearward ejection appears to cause the TW to rapidly spin around its CG, but it doesn't get to do very much of that before it hits the ground. One thing it doesn't do is lawn dart, so I guess that in itself is evidence that the Tumbleweed was actually tumbling during its return to Earth.
What may help it to tumble is the fact that the ejecting motor mount, which doesn't have all that much mass by itself, is anchored to the rocket by a leash running almost to the top of the rocket and then down the outside to its anchor point near the aft end of the motor tube. When it ejects and extends that leash to its limit, it gives the rocket a little off-center lateral jerk on the aft end of the airframe, right below the rocket's CG. I think that action might play a role in causing the rocket to tumble.
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Hey, this could be the only tumble recovery model that you could actually have a chance of catching after launching... LOL
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Absolutely! You will never have to walk far or search very hard for it after it recovers, either. Did you ever think that you would be able to launch your Tumbleweed over and over right in your own backyard?
Mark \\.