[SML] Rockets- onstage use

[Joe D]

To me, the actual rocket flight at launching is essentially invisible, because it is so fast.  However, the smoke trail is important. I don't think the flame should be visible, unless it is a night launch.

It may be viable to make a smoke trail, by creating a "air cannon".  This is simply a hole, perhaps the size of a quarter, on a drum like device. When filled with smoke, and the side of the "drum" opposite of the hole is hit, it will put out a quite focused smoke ring that moves quite fast.  But, it would take a succession of such blasts to fill the trail of the invisible rocket.

As I think more about it, you have to get rid of the rocket somehow. So, I think it may actually be best to have the rocket travel.  It can be on an elastic cord that is stretched out as the rocket is locked to the launch pad. The elastic might be directly tied to the rocket, but that may be fairly visible. So, an alternative would be for the elastic to be tied to fishing line, with the elastic running around a pulley above to lengthen it. The reason for the elastic, vs. just pulling on it, is that you can't quickly pull a cord the length you probably need it to pull. I suppose an alternative is that the cord is fastened to a weight that is dropped.

For the smoke trail, if the rocket is on a base, that is filled with smoke just before the launch, then it may draw the smoke up with it. Ideally, the smoke also gets into the rocket itself. The bottom of the rocket should be probably the full diameter of the rocket. If the rocket has some air holes towards the top, that may help the smoke inside the rocket to come out the end.

-Joe Dunfee