Several of us have had some problems with early ejection using the I285R motors. I mean waaaaay early, after about 1 to 2 seconds of boost.
We checked the Aerotech site and are using the recommended delay element for a medium delay.
So far (after a few months) Aerotech has not responded on this problem.
Is anyone else experiencing this? Has Aerotech changed the delay element?
Don Brown NAR Level 2
Don,
Please file a MESS report at
John Lyngdal NAR S&T Secretary
A couple of thoughts:
Are you certain that early ejection is the cause? Whenever I hear someone blame early ejection and it is happening just about the time of motor burnout, I think that drag (or inertial) separation should be considered first. But you probably already did but failed to mention it.
How were the delay elements stored? If they are not kept tightly sealed and away from propellant grains of Blue Thunder and Red Line reloads, migration of burn rate catalyst will result in shortened delays. You might have noticed that the warranty statement on the reload instructions now has a provision where the warranty is void if you assemble the motor more than a few hours (I forget exactly how many, twelve springs to mind.) before using it.
There have been several rocketeers at our launches with delays from Redline reloads not working properly. Nothing to the extent Don mentioned, but yes, they have been a second or two, or three early.
-Booms
TRA L3
One, two or even three seconds would be within the permissible variation for rocket motor pyrotechnic delays, depending on the specific delay time (+/-
20% or 1.5 seconds, whichever is greater).Gary
Agreed. Drag or pressure differential separation are the two most common causes of "early deployment" in HP rockets, especially when observed near motor burnout.
Gary
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