So this is the basic rocket that my Scouts built. The main tube is 12 inches, the fins are just cardboard and probably 4 inches long. They’re attached with hot glue, as are the pieces of straw which serve to guide it up the pole during launch.
And that’s what I’ve been nervous about. Would the available engines successfully lift the rocket?
When I first embarked on this, I considered it a non-issue because I was going to use a D size engine, which has plenty of lifting power. The problem is that the inner diameter of the main tube is not big enough to accept a D size engine. Rather, I have to resort to a C or B size engine. Thus, the set screws at the bottom to hold the engine in place.
I first started getting concerned when I noted how much lighter the boy’s kit based rocket is than the PVC versions. So I decided to weigh one of the PVC rockets and it comes in at 4.5 ounces. Looking at the chart, the maximum recommended liftoff weight is 4.5 ounces for a B6-2 engine. There are a bunch rated for 4 ounces. Making things worse, the 4.5 ounce weight did not include whatever engine I’d be putting in there.
I searched on the Web for something to give me some reassurance, but came up with nothing. In the end, I decided I was going to have to test it out. So this morning, I took the rocket and the boy’s launch pad and went out to where we’ll be launching these things from. In all, it took me about 5 minutes to setup. Thankfully, the place was empty as well.
I’m happy to report that the weakest engine I had, a B6-4 successfully lifted it off. Unfortunately, the parachute system didn’t deploy, but I can live with that. The rocket went up about 75-100 feet or so, traced a nice arc through the air and then buried itself about 3 inches into the ground on impact.
So the boys should have a good time shooting them off next week.