New Motor certified, April 2023

[prfesser]

Many, many thanks to Alan for his dedication to TMT. Pushing the button, watching the flame and smoke, listening to the ROAR...that's fun, but there's a lot of hard work that goes into motor certification that most rocketeers never see. Ya done good, Alan!

 

[kjhambrick]

One, less 'wasteful' way to perform additional motor testing would be to always fly the large, expensive Motors with an on-board, calibrated accelerometer and then share the data.

The Thrust -vs- Time Curves can be extracted by subtracting Rho-Normalized Coast-Phase Drag from the Acceleration during the Burn-Phase.

-- kjh

 

[JohnCoker]

But, the graphs give us a good chance to appreciate how much variation we can expect from a group of "identical" commercial motors. As I recall, there were various numbers of 3 different day codes in this batch of reloads. The total impulse numbers were very close, well within the NFPA 1125 criteria, but you can see that there was considerable variation in the max thrust points.

This is great data! So basically the max thrust variation makes the graph look a lot different, but the fundamental performance of the motor (total impulse) isn't much affected.

 

[FredA]

Interesting convo.
The total impulse will be pretty close as long as the motor holds together all the fuel is burned in a reasonable time.
The fact that the motor went [well] into it's design margin and is ignored seems just plain wrong.
Which leads me to question who made the total-impulse rule?