[SML] Rockets- onstage use

[billn at peak.org]

> 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.

Having a few decades of launching High Power Rockets, I may be able to provide
some useful information.

I have launched rockets that pretty much disappear when launched, but those
are the exception.  Most take about half a second to get to about 30 feet and
I have one that takes at least 3 seconds.

All have had flame visible, even in bright daylight - although the small Estes
type model rocket motors do not seem to have a visible flame.

Some have a smoke trail, some are pretty much smokeless. Any smoke is usually
white or black, depending on propellant formulation.

Be aware that, regardless of how the rocket is accelerated, that you will
probably need a guide line - both top and bottom. It is just about impossible
to get the fins perfectly aligned, so the rocket does not travel straight
without continuous guidance.

I like the idea of using two pulleys, one in the grid and the other at deck
level. The line would be in a continuous loop and there would be a weight to
provide the acceleration. The line on the bottom of the rocket stops its
upward motion after it is above the audience sight line.

This method also allows you to use a slow acceleration - there is no need to
have the relatively high acceleration needed for an unguided rocket. The
maximum acceleration you will get is 1 G, which would produce a height of 16
feet in one second and 36 feet in 1.5 seconds. It will be somewhat less
depending on the pulley frictions and the ration of the acceleration mass
compared to the rest of the mass (rocket + pulleys + line).

Bill