Alan Whitmore
Well-Known Member
- Joined
- Aug 27, 2013
- Messages
- 180
- Reaction score
- 482
TMT has recently simplified and "streamlined" the Data Acquisition and Recording package to make our testing sessions simpler and less prone to mistakes. I needed to test out the equipment and there are no commercial motors in the queue, so I looked around for something to run some tests with. I have a box of old BP motors, and a few new ones of the same size, so I tested the new equipment in my driveway, with some Estes B6 and C6 motors.
The "old" motors are from 2002, and have been stored "inside", according the the kind man who gave them to me, loose in a box, with no plastic wrap. That's all I know. The "new" motors were purchased from Apogee Components in June, and have 2016 date codes. I ran 2 old C6's, 3 new C6's, 2 old B6's and 2 new B6's. All of the total I and average I figures are well within the required parameters, as are the delay times, both old and new. Every delay time is short, often very close to the criterion for rejection. Not a single delay time, old or new, was less than a second too short.
The interesting observation was with a pair of motors I had never heard of. Even my year-long search of the archives had not turned up the Apogee C10-7, and there were 2 in the box in their original polythene wrap. This is a weird little motor, 18mm composite propellant, somewhat short, only 51mm long, black plastic case and a plastic nozzle, Packaged with an ancient 'copperhead', which I discarded. There was no date stamp on the motor or in the instructions, so I have no idea about the actual age. There must have been some form of copper in the propellant, because there was a brief spark of blue in the flame, and the total impulse and average thrust figures were precisely within requirements. Nominal 7 second delay, and the observed delay times were 16.57 and 16.64 seconds. Say wha!?!? I almost gave up and stopped recording. None of you have any Apogee C10's or or likely to acquire any, so we can close the discussion of these little anomalies.
I can only make one generalization about these observations. Both old and new, the total impulse, average thrust, and delay element timing for this small group of motors was essentially all the same. the big difference is in the vigor of the ejection charges. All of the new motors left the tube on top of the load cell with a smart 'pop', travelling off into the trees around the launch site. All of the older motors fired the ejections charges like a micro-sneeze, the motors left the firing tube at a crawl, sometimes only barely leaving the tube. My general admonition is that elderly BP motors may give you total impulse, average thrust, and delay charge timing very similar to the newer versions of the same motors, but the power of the ejection charges are not what you will expect.
Alan Whitmore
Chair, TMT
The "old" motors are from 2002, and have been stored "inside", according the the kind man who gave them to me, loose in a box, with no plastic wrap. That's all I know. The "new" motors were purchased from Apogee Components in June, and have 2016 date codes. I ran 2 old C6's, 3 new C6's, 2 old B6's and 2 new B6's. All of the total I and average I figures are well within the required parameters, as are the delay times, both old and new. Every delay time is short, often very close to the criterion for rejection. Not a single delay time, old or new, was less than a second too short.
The interesting observation was with a pair of motors I had never heard of. Even my year-long search of the archives had not turned up the Apogee C10-7, and there were 2 in the box in their original polythene wrap. This is a weird little motor, 18mm composite propellant, somewhat short, only 51mm long, black plastic case and a plastic nozzle, Packaged with an ancient 'copperhead', which I discarded. There was no date stamp on the motor or in the instructions, so I have no idea about the actual age. There must have been some form of copper in the propellant, because there was a brief spark of blue in the flame, and the total impulse and average thrust figures were precisely within requirements. Nominal 7 second delay, and the observed delay times were 16.57 and 16.64 seconds. Say wha!?!? I almost gave up and stopped recording. None of you have any Apogee C10's or or likely to acquire any, so we can close the discussion of these little anomalies.
I can only make one generalization about these observations. Both old and new, the total impulse, average thrust, and delay element timing for this small group of motors was essentially all the same. the big difference is in the vigor of the ejection charges. All of the new motors left the tube on top of the load cell with a smart 'pop', travelling off into the trees around the launch site. All of the older motors fired the ejections charges like a micro-sneeze, the motors left the firing tube at a crawl, sometimes only barely leaving the tube. My general admonition is that elderly BP motors may give you total impulse, average thrust, and delay charge timing very similar to the newer versions of the same motors, but the power of the ejection charges are not what you will expect.
Alan Whitmore
Chair, TMT
