Fair Certification Rocket?

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UPscaler

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A question for the prefects in this group (or anyone who cares to chime in)

This is my roommate. He has been wanting to get into high power. I was given a PML callisto that broke a fin loose upon landing. He pulled all the fins out, cleaned them up, shortened the airframe 9 inches, fiberglassed the airframe, cut new fin slots, assembled a new motor mount and rebuilt it from the ground up.

Would you let this fly for certification?

Braden

brennanrocket.jpg
 
Probably, but the person you have to convince is the Prefect who signs off. Did he take a picture while the fins were out and the motor mount taken apart? A picture like that would make it very easy.
I wouldn’t worry too much. People show up with built rockets for L1 all the time with the trust that they did the work. We have to take them at their word unless there’s a strong reason to doubt them. If the person who gave it to you spoke up and said “I gave it to him fully built”, there could be questions, but as long as your roommate can convince the Prefect he rebuilt it to the level you described, he should be good to go.
 
Probably, but the person you have to convince is the Prefect who signs off. Did he take a picture while the fins were out and the motor mount taken apart? A picture like that would make it very easy.
I wouldn’t worry too much. People show up with built rockets for L1 all the time with the trust that they did the work. We have to take them at their word unless there’s a strong reason to doubt them. If the person who gave it to you spoke up and said “I gave it to him fully built”, there could be questions, but as long as your roommate can convince the Prefect he rebuilt it to the level you described, he should be good to go.

Agreed.
 
I certainly agree with what has been said by the other guys. However, shortening the body tube by 9" will shift the CoG and CoP rearwards. In fact, the CoG will probably shift more, slightly reducing the stability margin. Just be confident that the stability is not compromised by at least simming the new configuration.
 
In my opinion, he basically turned it back into a kit and then rebuilt it. I'd sign off on the cert, assuming he could answer the questions that are normally asked (where is the CP/CG, what did you use to attach the fins, etc).

I wish him the best of luck on his cert flight!
 
I certainly agree with what has been said by the other guys. However, shortening the body tube by 9" will shift the CoG and CoP rearwards. In fact, the CoG will probably shift more, slightly reducing the stability margin. Just be confident that the stability is not compromised by at least simming the new configuration.
Luckily the giant fins kept everything in check according to Rocksim. The CG will be inspected with the motor in prior to flight, of course.



Braden
 
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