are Aerotech motors BP or composite?

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Apr 7, 2004
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Wow, I feel so dumb. Are Aerotech single use motors black powder or composite? What are Econojets? And can you stage a Aerotech BP motor to an Estes motor without electronics?
I was wondering about that... If the motor had no EC and a very thin delay, would it work then? I would think that the thin delay breaking through would produce the same effect as an Estes BP motor.
Originally posted by Blue_Ninja_150
If the motor had no EC and a very thin delay, would it work then? I would think that the thin delay breaking through would produce the same effect as an Estes BP motor.

The answer to this question lies not in the fuel material, but in the shape of the material. APCP motors are core-burners, whereas BP are end-burners. AP burns from the center to the outside, so the delay grain actually starts as soon as the rocket ignites.

so in theory you could use AP, however, it would need to be end burning which would require a powerful propellant. Grain Geometry..... good point wwattles
What would happen if you used two BATES style grains and one solid grain? Any possibilities there?

Actually you could *technically* direct stage AP to BP. Basically I'm saying it is possible. And grain geometry isn't an issue in my theory. All you need is a short delay grain. Let's use an F21-4W as an example. Remove the ejection charge cap, add a little more BP and tape it to any BP 24mm motor just as if you were direct staging two BP motors. As long as it doesn't turn into a bonus delay and as long as your rocket is light enough to coast a few seconds before staging, then you'd get a nice composite boost, a four second coast (or less if you can correctly cut the delay down), and a nice stage. I know this method works because I've done the same thing with A10 motors. I removed the EC cap, added more BP, and taped it to an upper stage A10. Boost, coast, nice pop of the BP and a great stage. It was a cool effect with the delay. So really, the booster motor propellant doesn't matter with this direct staging method as this utilizes the delay and ejection charge of any standard motor. So in closing, yes you can technically stage APCP directly to BP by basically adding more ejection charge to the booster and removing the ejection charge cap, and you can do it with BP motors too. Makes a great boost-coast-more boost effect.

While I'm at it, you can also *technically* turn this around and direct stage BP to AP. As long as the motors are the same diameter, and the BP motor is a booster motor, or has the ejection charge cap removed with more BP added, then you could just tape an AP motor with sheathed thermalite or pyrogen tipped quickmatch inserted into it, and extending out the back about an inch so it can come in contact with the burn through of the booster motor or the BP of the enhanced ejection -or in this case "staging"- charge. That could work...technically.

Mind you , this is all just theoretical except for my "A10 experiment". I'm just saying that technically, it can be done.

That is interesting and I can see in theory how it would work.
I would even go a step farther in the AP to BP staging and perhaps add a very course grain BP to the charge to produce more burning chunks, if you will, to enter the sustainers motor nozzle.
I somehow think some alterations may be against NAR rules but an interesting theory none the less.
The idea to beef up the ejection charge with some coarse particles/chunks of BP might work reliably and fine, or it might not. I kind of think you would be looking for trouble using that approach.

You have to remember that although BP is used in both the ejection charge and the last layers of booster grain, it is burning under significantly different conditions. When an ejection charge goes off the primary purpose is to create a relatively large volume of gas. Yes it will be quite hot inside the motor but hopefully will cool quickly as it expands into the rocket. Ideally the only thing mixed with the gas would be some ash and fine particulates, so the basic ejection charge is not designed to release large chunks of BP into the gas stream----the stuff you add would pretty much be it, as far as having pieces of BP available to light the next stage.

When a booster motor nears the end of its run and the remaining part of the BP grain gets thin enough, it ruptures under the pressure of the gasses in the combustion chamber. This projects relatively large chunks of burning BP toward the next stage.

I don't have any quantitative data on the particle sizes that come out the front of these two different types of motors, but I think you will see that boosters are optimized, by design, to be used as boosters. Fiddling around with other home-made approaches will probably not result in the same success rates. The manufacturers of these little BP motors have been practicing for quite a few years, and I think their way works better.
Thermalite! Learn to love it.

I've staged AP to BP motors, and AP to AP motors using thermalite many times. For example to stage an E30-4 to a D12, remove the paper cap on the E30 and dump out the ejection charge. Take a piece of thermalite stick the end in the D12's nozzle and tape it in place. The hard part is putting the rocket together so that the other end of the thermalite winds up in the hole in the end of the E30. The thermalite will take some time to burn so keep the length as short as possible or use sheathing.

The same technique works for AP to AP staging, though you must use sheathing to make sure the sustainer motor lites at the top.

Try it, it's fun!
Good explination Jeff...and good to point out you can direct stage AP to AP. Thermalite IS fun:D