Quick question about reload systems..

[blike]

On the DrRocket website, it says that the 29/240 case can be used for H-97J, H-180W, H-220T.

My question is whether or not this case will work with less power, such as a G75. If not, why not?

 

[rocketsonly]

I'm not totally sure why you can't use motors below the designate newton-second capacity, but I know it can't be done. Sometimes casings we have a rating such as the Aerotech 29/40-120, meaning motors designed for the case are in the 40-120 range. It does not however mean you can use ANY motor that is between 40 and 120 newton-seconds.

 

[r1dermon]

possibly because its too long. just a guess.

 

[Papa Elf]

The 40-120 motor has such a range because it varries its propellant lengths. The empty space between the propellant and closure if taken up with a spacer. The problem with this is there is a lot of mass. For example, and E18 would be lighter than a E16... since a E16 is loaded in a G size case. Also, this gap makes the motors harder to ignite. F40's are not that bad... but E16's are extremely stuburn. A definite Magnelite Only motor.

As far as the HPR motors... I don't think the bates grain configuration and the higher pressures these motors run at would work very well with a spacer. The G75 uses the RMS 29/180 case... those cases are very affordable.... and if you already have the 29/240, you can get just the 180 case for under $20, and borrow the closures from the 240.

 

[blike]

So it's really a problem of the extra volume severely reducing the efficiency of the motor?

 

[MarkABrown]

Originally posted by blike
So it's really a problem of the extra volume severely reducing the efficiency of the motor?

It's probably a lot more complicated than that. The most obvious reason is that the appropriate spacers wouldn't be available to put a G75 in a 29/240 case. You can't make your own spacers since that would be considered a motor modification thus making it an uncertified motor and disallowed at a sanctioned launch.