- This topic has 4 replies, 5 voices, and was last updated 10 years, 10 months ago by John A. Wilke.
February 23, 2010 at 3:17 am #40926greywolves
After all the helpful responses for the main chute, (thanks) lets talk about the drouge.
How many will use motor ejection for the drogue?
Motor ejection with BP charge as backup?
Drill out motor charge, use only BP for best dtermined apogee?
What are all the schools of thoughts here?
Hey, I’m curiuos guy and wheel works just fine, so….February 23, 2010 at 3:29 am #52180AdrianParticipant
If you’re using altimeter apogee deployment, you don’t have to drill anything out; just leave the delay/smoke in place and just skip the step where you add the BP. If you want to eliminate the possible failure mode of a delay element blow-by, then use a plugged forward closure. Otherwise, just use your regular closure and your motor will act like it otherwise would, but without the “pop” at the end.
Motor ejection is a good backup if you’re worried about setting up your altimeter correctly. In the long run though, it’s probably more reliable to skip any motor ejection once you have established good procedure with your altimeter, since it eliminates the failure mode of a premature ejection charge.March 29, 2010 at 6:55 pm #52181Steve JensenParticipant
I’m still considering using the motor as a back up, but only for some engines.
I am going to watch all the Little Dog DD launches closely.
I am going to attempt one with a J-600. The time going up exceeds the available engine delay. So, it’s altimeter deployment only.March 30, 2010 at 12:05 am #52182Tim Thomas
8) Skip the drough chute. Too much trouble for to little gain. Pop it and just let her fall. Glass rockets are way tough. The main will do the work. IMHOMarch 30, 2010 at 3:58 am #52183John A. WilkeParticipant
Motor ejection of the drogue can often do more harm than good… Altimeters like Adrian’s (and others) are so reliable that you don’t have to worry about motor ejection. If / when you use it, the darned motor always seems to have a delay that is too short.
Drogue chute… I’d skip it. Let ’em drop. I can literally count on one hand the number of times I’ve used a drogue chute. Just break them and drop them and you’ll be fine. Less prep, less cost, less entanglement, less everything. I’d personally only use a drogue chute if I had a project over 30-40#… and I might even forego it then.
Many years ago, Jim Rosson, Paul Robinson and I round-tripped a rocket named “Butt Ugly” 😳 7 times on 98mm loads in one day at an LDRS. BU was “portly” – probably near 100#. We used a 1/4 plastic-coated stainless cable for a shock cord. We dropped it w/o a drogue every time. It was fine.
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