I never thought I’d share ALL my secrets on altitude, but here they are… in no particular order. Note that some will disagree with some of my stances here, but they have served me (very) well over time. Now, in no particular order:
- Lose the lugs and rail buttons. Tower launch for optimal performance. It doesn’t make a LOT of difference, but it sure does make enough to do it.
- Minimum diameter is a MUST. There is simply no substitute for this one. Remember, the hole you are boring through the sky is calculated at 3.14*r*r. That means any increment is magnified considerably…. Look at it this way – a 16″ pizza is actually 4x the size of an 8″ pizza (trust me). An 8″ pipe carries 4x the water that a 4″ pipe carries. A 98mm rocket has to punch a hole that is 3.29X the size of a 54mm rocket.
- Von Karman nosecones are key - assuming your velocity is above mach for an appreciable amount of time. Conical is typically the next best, followed by ogive. Your actual mileage may vary. Much depends on your flight profile.
- Tailcones help – a LOT. They are also a tough thing to work into a minimum diameter rocket, but trust me – it can be done (and I’ll soon have a kit to prove it!)
- Optimal mass comes into play. This is one that will spark some lively discussion around the campfire – but I firmly believe in it. Lighter is not always better. I like to use the example of throwing a wadded up tissue with and without a rock wrapped inside. Sometimes – more often than you think – heavier is better.
- Little fins are better than oversized fins. It is all about drag…
- Shorter is better. Much of a rocket’s drag is dependent on the rocket’s length. Go as short as possible. I once calculated how short I could make a rocket, and then I cut the tube back two inches to force me to get creative. Believe me, you can get pretty creative.
- Finish must be very smooth. Duh. But it can’t be emphasized enough. I like to paint a rocket with Kilz primer and then wet sand it before and after every flight.
I’m sure there are other things, and I’d love to hear your tricks (now that I’ve spilled my guts on all of mine)!