I have a few questions for the skilled rocket craftsmen and engineers of TRF. Here are my intentions:
3" tube fin design with 54mm motor mount - I want the flexibility of flying any CTI motor from 38mm (assuming safe thrust-weight and velocity off the rail) to a 6-grain, 54mm (possibly 6XL, but don't own that case....yet)
Initially I was thinking about Blue Tube for the airframe and tube fins. However, I am really intrigued with what I have read/seen on TRF regarding the MAC Performance canvas phenolic tubing and would really like to try it. The biggest downside is that it is about 2x the cost of Blue Tube per inch, and I will have to pay shipping (Apogee is close enough that I can drive to buy Blue Tube there). But, if it matters for my questions below, let's assume MAC Performance's canvas phenolic tubing.
Nose Cone TBD - I'm up for suggestions here. The cones that MAC Performance sells are 5:1. For what I have in mind aesthetically I want a shorter rocket with a shorter looking nose cone (maybe 3:1).
Dual Deploy using nose cone volume (and short payload section if necessary) to pack main chute
GPS transmitter (TBD) housed in av-bay aft of nosecone
Tube fins cut at angles both foreward and aft (not a 'square' 90 degree cut) - think of a similar profile as the Madcow DX3 fins except with tube fins
Aeropoxy ES6209 for all bonding
Possible name: 'UNFINITY' is the only one I keep coming back to
OK. Here are the things I need help with:
1) I plan on borrowing a friends 12" chop saw capable of angled cuts (but not compound angles/mitres) to cut the tube fins. Any suggestions on how to keep track of the long axis of the tube fin when I turn it around to make the second angled cut with the chop saw?
2) I want to keep the rocket as light as possible. What is the shortest length you would go for the 54mm motor mount? My Aeropac 54-38 adapter is just over 7" long, so I need it at least long enough to fit it. Remember I want to be able to fly 6 grain 54s (possibly 6XL).
3) Again, for weight considerations, 2 or 3 centering rings for the motor mount? If it makes a difference in your answer, I will most likely order the centering rings from MAC Performance and they make an aft ring that is stepped, so it also functions similar to a thrust plate.
4) Any thoughts on how the angled tube fins will react at higher velocities? For sake of discussion, right now my design sketches have the 'root' edge of the tube fin at 3 calibers (9"). I am anticipating the outer edge of the tube fin tapering to one caliber (3") in length. For strength considerations I don't think I should go any 'thinner' than that, but I have no objective information to justify that thinking.
3" tube fin design with 54mm motor mount - I want the flexibility of flying any CTI motor from 38mm (assuming safe thrust-weight and velocity off the rail) to a 6-grain, 54mm (possibly 6XL, but don't own that case....yet)
Initially I was thinking about Blue Tube for the airframe and tube fins. However, I am really intrigued with what I have read/seen on TRF regarding the MAC Performance canvas phenolic tubing and would really like to try it. The biggest downside is that it is about 2x the cost of Blue Tube per inch, and I will have to pay shipping (Apogee is close enough that I can drive to buy Blue Tube there). But, if it matters for my questions below, let's assume MAC Performance's canvas phenolic tubing.
Nose Cone TBD - I'm up for suggestions here. The cones that MAC Performance sells are 5:1. For what I have in mind aesthetically I want a shorter rocket with a shorter looking nose cone (maybe 3:1).
Dual Deploy using nose cone volume (and short payload section if necessary) to pack main chute
GPS transmitter (TBD) housed in av-bay aft of nosecone
Tube fins cut at angles both foreward and aft (not a 'square' 90 degree cut) - think of a similar profile as the Madcow DX3 fins except with tube fins
Aeropoxy ES6209 for all bonding
Possible name: 'UNFINITY' is the only one I keep coming back to
OK. Here are the things I need help with:
1) I plan on borrowing a friends 12" chop saw capable of angled cuts (but not compound angles/mitres) to cut the tube fins. Any suggestions on how to keep track of the long axis of the tube fin when I turn it around to make the second angled cut with the chop saw?
2) I want to keep the rocket as light as possible. What is the shortest length you would go for the 54mm motor mount? My Aeropac 54-38 adapter is just over 7" long, so I need it at least long enough to fit it. Remember I want to be able to fly 6 grain 54s (possibly 6XL).
3) Again, for weight considerations, 2 or 3 centering rings for the motor mount? If it makes a difference in your answer, I will most likely order the centering rings from MAC Performance and they make an aft ring that is stepped, so it also functions similar to a thrust plate.
4) Any thoughts on how the angled tube fins will react at higher velocities? For sake of discussion, right now my design sketches have the 'root' edge of the tube fin at 3 calibers (9"). I am anticipating the outer edge of the tube fin tapering to one caliber (3") in length. For strength considerations I don't think I should go any 'thinner' than that, but I have no objective information to justify that thinking.