Ejection charge question

[Jeff]

Being new to RMS I am wondering about 1. the amount of powder to use in a given rocket and 2. the proper way to load the powder. The Aerotech instructions say to shake the motor so the powder settles into the aft hole and abuts the delay charge. SHould I put in a chunk of wadding over the charge with a piece of tape over it so the powder stays put?

 

[dixontj93060]

Originally posted by Jeff
SHould I put in a chunk of wadding over the charge with a piece of tape over it so the powder stays put?

Probably could, but not really necessary. The charge cavities for most 29mm and 38mm motors hold a pretty small amount of BP. Normally you can just fill them up and double cross with masking tape and then wrap this tightly around the charge well laterally (perpendicular to the length of the casing) and then trim off any straggling edges. You will have an adequate charge and, more importantly, it will be well contained.

-Tim

 

[Jeff]

So the bp does not have to be pressed against the delay element?

 

[cjl]

Although it doesn't have to be, I usually use a small piece of wadding anyways, for peace of mind as much as anything.

 

[Brian Barney]

Originally posted by Jeff
So the bp does not have to be pressed against the delay element?

it should be, that way you know its gonna light, but when the delay gets to the end of the burn it should put enough fire up through the pinhole to light the bp. Also, the sticker they give you in the rms loads (if its hpr) doesnt work well, so I always put more tape over it, usually masking tape so it wont slip off in flight or transportation.

 

[dixontj93060]

Originally posted by Jeff
So the bp does not have to be pressed against the delay element?

That is why you shake the motor so it sifts down into the hole adjacent to the delay element.

 

[Jeff]

Yes that round sticker in the kit does look pretty iffy

 

[loopy]

Originally posted by Jeff
Yes that round sticker in the kit does look pretty iffy

I usually put that right on top of the BP, then put masking tape over top of that to make sure it's not going anywhere.

 

[blackjack2564]

Wrap the masking tape around the knurled part of the closure just below the edge of well you put your BP in, leaving most of the tape above the well.Now you have a cup. Put in your BP then fold over the tape towards center, and you have a good tight seal. Put in some wadding if it makes you sleep better. FYI.....some one correct me if I'm wrong, but if I remember right, the 29mm's come with .7 grams bp and the 38,s 1.5 grams.Unless it is a very small rocket, I will add more bp. I,m from the old school.......Blow it out [parachute] or blow it up !