Should This Model Have A Stuffer Tube?

[Aramus]

I'm building a large tube finned rocket for an L-1 attempt. The rocket's core has BT-60 body tubes reinforced with BT-60 coupling tube. The overall length is approximately 66 inches. Should I include an interior stuffer tube to ensure ejection?

 

[TRFfan]

Probably not. However, it wouldn't hurt to put it in there.

 

[rharshberger]

Really isn't necessary, as the ejection charge for an L1 motor should be plenty. I fly a double tubed Mean Machine clone on G motors with the stock Aerotch ejection charge no problems.

 

[Flyfalcons]

Probably far less interior volume on that than a 3" Leviathan, and those don't run stuffer tubes.

 

[cbrarick]

consider a high powered tube such as loc.

it will be stiffer and also much more sturdy.

 

[T-Rex]

Ground test, then you will know. Or, add a little extra BP and use a long shock cord...

 

[The_Lone_Beagle]

Probably far less interior volume on that than a 3" Leviathan, and those don't run stuffer tubes.

My thoughts, exactly. I inserted a stuffer tube in my Leviathan, because of this concern. However, with a BT-60, I would not be concerned. Even if it is 60+ inches long, I don't see the ejection charge losing much in the way of pressure/momentum.

That being said, it wouldn't hurt...but necessary? I don't think so.

 

[dr wogz]

Curious, any "volume rule of thumb" for "standard" ejection charges? Say, no more than 163 in3 of internal volume for a standard 'Aerotech G SU'? or for 1g of FFFG powder?!

Too many variables?!

 

[rharshberger]

Actually you could use a BP calculator based on the volume of the airframe, to determine minimum amount of BP to bring the pressure to X psi, and if the Estes or other motors dont produce enough volume of gas, then a stuffer tube could be used to reduce the airframe volume until it does produce enough volume. I yse a BP calculator spread sheet to determine my starting ejection charges for HPR rockets. LPR rockets generally have a ejection charge that cant de easily modified so altering the internal volume would be a safe alternative.
While ground testing LPR isnt usually done, rigging a used motor to be a testing charge holder is easily doable.