OhhhhNooooooo! I really do not think this will be a setback as much as a challenge to rebuild.
I have been thinking about this rocket popping Mach. My thoughts are that the size of the tubes themselves may be the reason it survived. The 3" tubes would be a lot less flexible than, say, 4".
You should post plans for the Bluefin Tuba --- that wide a motor range is really impressive. I want one.
reading comprehension fail. ThanksHe did think it's on the second page or start of the third
I wonder what stress difference there is on airframe diameter . My thinking is bigger diameter the more area for stress load . But I see your point . The smaller airframe would load less due to the smaller area
Thank you for your compliments Dan. As the man says, simplificate and add lightness. The very features that you are adding to increase strength are increasing your mass--to a point where you feel that your rocket is at a disadvantage. As for "punching" through Mach, BFT flew on the slowest-burning commercial M available. When the same motor ripped the fins off a Magnum in 2013, the consensus was that it took too long to transition through Mach :=)
Ari.
Ok, welp, I just ordered the parts for a Bluefin Tuba 54. That's an impulse range I'm likely to fly more often. Cost of airframe + NC, ~$60.
...and I just realized, five minutes after sending the money, that I have no plan for motor retention. Hmm, maybe time to brush up on lathe skills...
Another thought I entertained and rejected was gluing the fins to extend 1/2" or 3/8" below the fuselage. I would drill each fin in the side that faces the motor, put a t-nut or a clip nut in, and use 6 machine screws (one through each fin, pointing toward the nozzle) to hold the motor. Upside is cheap and lower drag than Aeropack. Downside is undoing 6 screws between flights.
Ari.
Motor eject, altimeter single-event, or head-end DD depending on the flight and the motor. Yeah, in practice I'll probably friction + tape, or do the circumferential screws. If the latter, I'd definitely only use two. Oh, and definitely adapt down using matroshka'd MMTs.Are you planning on motor ejection or electronics? Are you planning on adapting down?
I used an Aeropack retainer on BFT 3" and paper tape on BFT 1.5". Especially with electronic deployment and plugged (tapped) closers, I'd feel very confident using tape even on 3" version, and certainly on 2". With motor acting as recovery attachment point, the worst that can happen is rear ejection.
Another thought I entertained and rejected was gluing the fins to extend 1/2" or 3/8" below the fuselage. I would drill each fin in the side that faces the motor, put a t-nut or a clip nut in, and use 6 machine screws (one through each fin, pointing toward the nozzle) to hold the motor. Upside is cheap and lower drag than Aeropack. Downside is undoing 6 screws between flights.
Ari.
I"m pondering a BFT 3" of my own and a have a few questions.
1. In your original BFT 38mm thread you started with a standard 48" long Blue Tube and cut the 2" long tube fins from that. How long did make the fuselage and the tubefins. How long is the body tube on the 3" version? I'm thinking to order two length of BT.
Never mind...I found the description. 48" long just as it came from the factory...and two tubes required.
2. Looks like the BFT 3" is a single length airframe without a mid body alt bay. Did you use a Cable Cutter set up and altimeter in the NC?
15K with not dual deploy? You usually do things unconventionally so I would believe it. LOL!
This build is all yellow glue. This is one of the points this build aims to drive home, that you can do it with yellow glue alone.
Fin length is less important. I make them slightly longer than diameter, mostly for mechanical rigidity considerations.
Ari.
Nosecone. There are photos in the thread.
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