29mm Minimum Diameter

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eggplant

eggplant

L3 | NAR 93664, TRA 17791
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Suppose I wanted to make a 29mm by 8 foot scratchbuild. What brand of tubing would you use? I can't find many options...
Also, what you do for retention(other than buy Aeropack, too pricey!)?
 
I would use Blue tube, not to pricey and very strong. Why is it 8 feet long?!
 
Thanks! I had forgotten about BT. About the length, why not? I am not going for performance!
 
Hmmm... Normally with a minimum diameter design you are doing so for performance. Stretching it to 8' really defeats the purpose. Why not just do a Blackhawk 29?
 
That is exceptionally long, so I would worry about strength, stability, and recovery issues. I built a 38mm x 6 ft rocket a while back and it was very long and thin. Really dangerous looking, and that did feel like the limits of any sport (not competition super-roc) rocket that was going to fly on mid or high power. Flew it a bunch of times on G125 motors.

In any event, if you go 38mm x 72 inches, or 29mm x 96 inches(!) the best but expensive choice would be wound fiberglass from giant leap or hawk mountain etc. If they had it in 29mm, you could go with dynawind from Giant Leap rocketry to save some cost and weight over the above options. For extreme cost, there is carbon fiber as well. I doubt phenolic or blue tube will be able to handle flights at that length, but would love to see you prove me wrong on that. My concern is that there will be flexing in flight that will result in a shred, because 8 feet is very long for a 29mm tube. Even fiberglass will flex at that length.

For retention, you can go with electrical tape or friction fit for a minimum diameter rocket. Electrical tape has never failed me, and runs about 10 cents per flight. For recovery, you may consider having the rocket split in half and recover in two sections. Please include updates and pics!
 
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What about the Estes Mean Machine? Isn't it similar proportions?
 
eggplant said:
What about the Estes Mean Machine? Isn't it similar proportions?
Click to expand...

6 feet x 40mm, so similar to my fiberglass hpr rocket above, but with a low power motor. And lets not pretend that mean machines don't fold up from time to time : )

You are talking 30% longer and 25% thinner! If you want to go cheap, 9 ft of 29mm phenolic tubing from Giant Leap is not so bad. (Three sections 36 inches each, plus two 12 inch couplers will maybe run you $50.) One benefit, despite my concerns above, is that phenolic wont be as dangerous if there is a recovery failure. But either way, these long rockets tend to flat spin if there is a recovery failure.

Your RSO may not let it fly to be honest. Another issue is how to do the fins, recovery, and what nosecone to use etc. Also what motors are best? High thrust to get a heavy rocket moving, but not so much as to flex it in flight? Also low wind would be crucial for this one.
 
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I would suggest blue tube. It is on the heavy side but it is thicker and should work fine.

I should add that my only experience with BT is a 5.5" 25ft tall Upscale Mean Machine.

Pictures for sure.

Also another word of advice is to be careful about motor selection. To much motor will break the rocket in half, to little and...well...you know.

Bryce
 
I've made a scratch build with bt-55(1.325''), 62'' long fine on C11s....3 flights.
 
Well, I guess I have some thinking to do... Thanks for pointing this out and preventing me from doing something stupid. That's what TRF is for!
 
I've built a 29mm Blackhawk-beater (using no CF or glass) and it's been to just around mach and back with no damage. I used LOC 29mm motor mount tubing and Blue Tube connectors, both from Apogee, and both pretty cheap.
 
29mm bluetube is pretty thick walled. As long as you use a long coupler I'd imagine it'd do well. I've never tried it, but it'd be interesting to see.
 
The EGE said:
I've built a 29mm Blackhawk-beater (using no CF or glass) and it's been to just around mach and back with no damage. I used LOC 29mm motor mount tubing and Blue Tube connectors, both from Apogee, and both pretty cheap.
Click to expand...

How long was it?
 
New Ocean said:
6 feet x 40mm, so similar to my fiberglass hpr rocket above, but with a low power motor. And lets not pretend that mean machines don't fold up from time to time : )

You are talking 30% longer and 25% thinner! If you want to go cheap, 9 ft of 29mm phenolic tubing from Giant Leap is not so bad. (Three sections 36 inches each, plus two 12 inch couplers will maybe run you $50.) One benefit, despite my concerns above, is that phenolic wont be as dangerous if there is a recovery failure. But either way, these long rockets tend to flat spin if there is a recovery failure.

Your RSO may not let it fly to be honest. Another issue is how to do the fins, recovery, and what nosecone to use etc. Also what motors are best? High thrust to get a heavy rocket moving, but not so much as to flex it in flight? Also low wind would be crucial for this one.
Click to expand...

LOC tube is plenty strong for such a project. Keep it below 85% mach and it will hold up suprisingly well. As far as thinner, well LOC tube is thicker than Estes tube and the smaller the diameter the less thick that it would need to be to be structurally sound. As far as stability you will need to be concerned that it is overstable, so keep the fins small. CG should be two diameters in front of the CP.
 
I say go for it. Id like to see an 8 foot 29mm rocket fortune favors the bold. :cool:

TA
 
karlbaum said:
LOC tube is plenty strong for such a project. Keep it below 85% mach and it will hold up suprisingly well.
Click to expand...

EGE said:
Full length (fin can + ebay + nose section) it's 1.35 meters - 53 inches.
Click to expand...

Okay just to be clear, we are talking about 8 feet in this thread. I would suggest phenolic at the least, blue tube if you can afford a bit more, and ideally some kind of composite. Certainly a composite first half would be helpful on recovery.
 
This 3 year old thread is being revived by a fresh 44 year old BAR. I have only been back in for a few weeks and am already becoming obsessed. I thought it would be fun with my five year old daughter but it's way beyond that already. My first scratch build as an adult after 30 plus years away is going to be this 8 foot plus 29mm Blue Tube minimum diameter rocket. I have all the parts and the G80 in hand to build it and launch it. I have 2 four foot sections of 29mm Blue Tube and one four foot section of matching coupler. This one will use the matching Urethane nose cone. I am using a 3D printed fin camI located on Etsy. The coolest part about it is I can drive around with this rocket strapped on my truck's roof fishing rod rack without worrying about hurting it. My name is Nantucketdink and this rocket will be known as Surfroc. It will be separating right in the middle which I have no experience with. The build begins tomorrow...
 
Excellent! Welcome to the Forum, and looking forward to seeing the Rocket.:)
 
Welcome to the forum! That is awesome to hear! I never ended up building this rocket, but maybe I will after seeing some pictures of your's.
 
DizWolf said:
29mm bluetube is pretty thick walled. As long as you use a long coupler I'd imagine it'd do well. I've never tried it, but it'd be interesting to see.
Click to expand...

I have seen a full length blue tube coupler on apogee if you you put one or two in your rocket it will be pretty solid...
 
I used the whole 4 foot coupler in mine (one not two). Blue tube is tough as hell to begin with, but double walled at 29mm is one strong body tube.
 

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