It didn't work right. Ballistic entry is not a good thing with model rockets.

I wasn't sure how to prepare it, and wasn't comfortable leaving the engine/motor/propulsion unit/fire-making-thingy hanging down at the bottom of the clip. It seemed to me that if it took off upward and smacked into the nose cone, it wouldn't be a smooth launch and might even knock off the knose kcone.

So, I put a small amount of tape around the engine to hold it snugly upward in the engine tube.

But, that snugness kept the ejection charge from pushing the engine casing backwards so that the rocket would become unstable. Instead, it remained stable and came in hard.

What do you guys do - including you guys as the ones that launch the Scout, and even you guys that just have some kind of response to an open ended question such as that?

BTW, it still has its spot on the shelf. It earned it.

Attached Thumbnails

 

The engine should be left loose. A very thin piece of copper wire is supposed to be glued to the side of the tube. This is bent over preflight to hold the engine in the up position but is thin enough for the engine to release at ejection (the wire is thin enough that the ejection "straightens it" and will allow the engine to fall to the bottom of the engine hook).

Some thoughts on this rocket:

I agree with Scott, the motor needs to be loose. But not too loose. Two things concern me if it's too loose. One is that the ejection charge will impart too much momentum to the motor thereby causing a hard impact with the end of the motor hook which might cause the hook to deflect and release the motor, or the motor to rip the hook loose from the rocket.

So I like to put just enough tape on the motor to give it a little sliding friction. This will also help keep the motor from bouncing off the hook back up into the airframe (thus making it ballistic).

Speaking of ejection charges, another problem can be the very stout charges found in some of the 13mm motors. To address that, I made the hole a bit larger on the airframe, hoping that would relieve some of the pressure and thus result in less aft momentum being imparted to the sliding motor.

Another thing I did to combat some of the issues with this rocket was to add a wire loop to the motor which wraps around the motor hook. The intent was to prevent the hook from deflecting sideways (when the motor hit the end of it). This ensured the motor stayed with the rocket and thus (theoretically) made the rocket tumble (See attached.)

Lastly, when flying the Scout, only fly it over soft ground. Ground that's been unwatered for two+ weeks in the Texas heat (for example), 100°F here lately, will be hard and, even with a perfect tumble, can break a fin.

Doug

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Attached Files

Scout-Hook.pdf (7.7 KB, 22 views)

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YORF member #11

Another method of holding the motor forward before launch is to put a clothespin low on the launch rod. The motor is supported by this and the rocket stays all the way down on the motor by gravity. I agree with using a bit of masking tape on the motor too.

Joe

I built a bunch of these as a kid and never used the thin copper wire that came with it. I always just let the motor "fly" up the body tube and though it did slam into the nose cone, it was never a problem. The reasons I lost them was because I insisted on only buying C motors as a kid (thinking "Why pay the same money for half the propellant?") and they'd disappear into the woods, or the motor would eject out the back and it would come down ballistic. Never had a motor fly through the nose cone just letting the motor launch itself into the body tube.

I think I might go without any tape, along the lines of Coconuteater64's suggestion. I have one in BT-5 size and one in BT-30 size, so I'll just see how it works with the engine slamming into the nose. If anything else, I could try the clothes pin trick.