Does the strength of the ejection charge increase with impulse?

jahall4 · Aug 27, 2015

Take two 24mm single use aerotech motors say an E11J and a F32T. On its face one would expect the F32 would produce more volume and/or force because it would be needed for larger air frames (more drag, volume, mass of recovery components etc...) it would no doubt be lifting, but I have never noticed any specs on the strength of an ejection charge.

rharshberger · Aug 28, 2015

Somewhat, here is a list in the following link.https://www.rocketryforum.com/showthread.php?68188-MPR-HPR-reloadable-motor-BP-ejection-charge-masses

Larger motors do have larger ejection charges, however its up to you to determine the proper charge size for your rocket. I don't even bother with the original motor ejection charges any longer, now I ground test all my rockets that use reloadables to get the ejection results I feel comfortable with.

jahall4 · Aug 28, 2015

Thanks Rich, I'll give it a look see.

I was asking about single use. Are you saying there are single use motors with a configurable "charge size"?

rharshberger · Aug 28, 2015

jahall4 said:
Thanks Rich, I'll give it a look see.

I was asking about single use. Are you saying there are single use motors with a configurable "charge size"?

I am not sure about SU motors since I haven't flown them yet. I know that reloadable motors do have ejection charges that can be adjusted. Someone with experience with SU motors will need to chime in on that, sorry.

Kruegon · Aug 28, 2015

If I understand it correctly, DMS motors are single use and have configurable delays and ejection charges.

chrisudy · Aug 28, 2015

Kruegon said:
If I understand it correctly, DMS motors are single use and have configurable delays and ejection charges.

That is correct. I used one last weekend. If I remember correctly, the instructions say to use the full ejection charge for airframes greater than 2.6", 1/2 the charge for smaller.

Chris

jahall4 · Aug 28, 2015

Thank guys, didn't know that about the AT DMS line. Looks like these start at 75mm, any 24mm with configurable EC (or are possibly known for stronger charges)?

chrisudy · Aug 28, 2015

DMS are available in 29mm, 38mm, 54mm and 75mm, according to Aerotech's website.

Chris

jahall4 · Aug 28, 2015

chrisudy said:
DMS are available in 29mm, 38mm, 54mm and 75mm, according to Aerotech's website.

Chris

thx, Good to know, I was looking at a press release on the larger motors.

Does the strength of the ejection charge increase with impulse?

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Does the strength of the ejection charge increase with impulse?

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