How do you stage composit rocket engines?

I am building a rocket and i want to use two or so F engines, how do i stage these

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S1L3N7 SWAT8 years ago
It's been a long time since I've launched any rockets, but the way I did it was tape them end to end. So you have one engine with the nozzle side clear, and another taped with the nozzle side to the open end of the first engine. When the first engine burns through the thrust phase and fires off the ejection charge it will light the next engine in the series. You can rig them up to fall off once they light the next one, but that depends on the design of the rocket. Some multi-stage rockets have fin sections that fall off with the engine, so for example a 3 stage rocket would have 3 sets of fins on it, and the last one stays on the rocket. Since the engines burn through completely leaving just a hollow tube, you could probably get away with them staying on, but that may cause balance issues since the thrust is now originating from higher up the rocket. Anyway, hope that helps you some.
If you search for it, you will find software that simulates based purely on mathematics what is possibly going to happen with a rocket design, the type of fuel and the amount of thrust it can produce as well as burn time and the design will also factor in how the rocket will perform. That way, you can test easily and safely and cheaply any number of scenarios before you actually try...
Prfesser8 years ago
As garmtn says, composite motors are different. First, no one makes "booster" composite motors; all have delays. Second, they must be ignited at the forward end rather than at the nozzle end. Taping the motors together works for blackpowder motors (Estes, etc.) but usually does not work for composites. Which means that there are two general choices: 1. Use an electronic timer with a g-switch, or altimeter, along with a proper igniter, to ignite the second stage some time after the first stage ignites or after liftoff. 2. Use reliable timing fuse to ignite a proper igniter in the upper stage. Usually the timing fuse is ignited at the same time as the lower stage, and provides a fixed delay before it lights the upper-stage igniter. The latter method requires some trial and error. Most of the folks who fly big rockets (H-O power and higher; check out www.tripoli.org) use electronic altimeters. They aren't cheap --- on the order of $100 --- but they are reliable if properly installed.
peoplerstupid (author) 8 years ago
I found the answer to this on apogeerockets.com the only way to stage composite engines is to use staging electronics
garmtn8 years ago
Hi, If anyone was paying attention he said," composite" motors. The fuel is way inside, hench the long copper igniter. Sooooooooo, don't know if the old "standard" method of staging will work. You can try that with a backup. A piece of "fast burning fuse" in upper motor. As long as 1st motor a booster, don't see why wouldn't work.
KentsOkay8 years ago
I know there are some articles their on multi-staging. However, F engines are pretty big, you may have to seek a more technical means to prevent catastrophe
peoplerstupid (author)  KentsOkay8 years ago
yah, i changed the design and now I'm using D's for the first two stages and an E for the last stage
I'd do E > E > D, and reduce the tube diameter on the last stage.
2 F's! That is quite some power. Anyway, the easiest way to stage 2 rocket motors is to stack them on top of each other, in two stages. Build the top like any single stage rocket, then build the lower stage. You'll load this form the top, pushing the engine in to the fuselage in the opposite direction the rocket will be traveling. Put a thrust ring in the bottom of the lower stage, so the engine will but against it. When the engine is ignited, it will push up against the engine above it. To load the rocket, insert the upper motor. Then tape the lower motor two the upper, and slide the lower stage fuselage over.
Tip: Rotate the lower stage to stagger the fins, increasing fin area and stability.
P.S. Remember to use a F-0 motor, you'll blow up rocket! If this is your first multi stage rocket, you might want to start with a kit, such as the "CC Express.":