Imteresting D12-0's.

[n3tjm]

I was browsing the local Hobby Lobby near my brother's house. They had two two packs of D12-0's. One of the packs the propellant almost filles up the entire case (maybe 1/4" of space left). The other pack of D12-0's looks like it had the normal amount of propellant in it.

Im wondering why there was so much more propellant. Is this the new normal or this pack of motors is an odd-ball.

 

[Andrew_ASC]

Put it in a rocket you don't mind blowing up and let us know what happens, rofl.

 

[Andrew_ASC]

Manufacturing defect on filling is what this sounds like.

 

[rockets]

I had something like this with some C6-5's. One of the motors was completely filled up to the top. I burned the motors, and they were fine. As ANDREW_ASC said, put it in a rocket that you don't care about.



Thanks,

 

[dhbarr]

My guess would have been mislabeling / mispackaging.

Did the material look right / the same on both of them?

 

[samb]

Two D12-0s I have handy have approx. 5/8 inch space. Both are at least 2 year old purchases. A note to Estes customer service might be in order here.

 

[Buzzard]

The difference in space above the propellant is due to the fact that each batch of the black powder received is different. The BP used is actually modified, I believe with clay, to lower the burn rate so that the burn rate is suitable for model rocket motors. A manufacturer will static fire motors made from the new BP shipment to determine its specific impulse and the amount needed to meet the rated impulse of the motor. This will effect the length of the propellant grain. You will see the same sort of differences in motors with delays. The same designation, say a C6-5, may have the end cap recessed or at the very end of the casing.
NAR Standards and Testing Committee minion 1969-1972.

Chas

 

[dhbarr]

Huh. Suddenly I feel the urge to buy up a couple of these LPR collections, stop that.

 

[MichaelRapp]

I had something similar with some D12-3s a few years ago....apparently it is not uncommon, and Chas' explanation makes sense.

(https://www.rocketryforum.com/showthread.php?120411-Is-this-variance-in-these-D12-3s-a-problem)

 

[dhbarr]

Note to self: when weighing motors, don't forget to mark propellant length and CG.

 

[n3tjm]

I went ahead and bought a pack of the curious D12-0's. Here are a couple pics of them.