The Speed of Sonotube?

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K'Tesh

K'Tesh

.....OpenRocket's ..... "Chuck Norris"
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I'm mindsimming a few rockets, and Sonotube looks to be the logical foundation material for them. However, I don't know jack about large diameter, Mach 2+ rockets, nor what it would take to make something like that.

What would a person use to make a ~10" (give or take) OD, 4 motor cluster rocket capable of Mach 2?
 
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CoyoteNumber2 said:
Sonotube is made to come apart, so definitely some lamination.
Click to expand...

That's part of the answer. Carbon Fiber? Fiberglass? Is there a limit to what can be laminated to Sonotube where the weight and strength are sufficent to allow the stresses of the design with the stated goals? I mean that if the amount of FG or CF would be so much that the rocket will be too heavy to fly, or too weak to survive the stresses, then what would be the best material for something like this?
 
All the Sonotube rockets I've seen have been big, low, and slow. You're going to need a lot of motor to get a 10" rocket to Mach 2.
 
mikec said:
All the Sonotube rockets I've seen have been big, low, and slow. You're going to need a lot of motor to get a 10" rocket to Mach 2.
Click to expand...

Remember, I have no idea if this is possible or not, nor do I know the costs involved... The sim is calling for 4xN5800-CS-P, and has it going at Mach 2.06 to 25,898'.
 
K'Tesh said:
Remember, I have no idea if this is possible or not, nor do I know the costs involved... The sim is calling for 4xN5800-CS-P, and has it going at Mach 2.06 to 25,898'.
Click to expand...

I am not liking the idea of sonotube and four n-5800. You would need some seriously strong rocket for that.
 
Use the sono-tube as a disposable mandrel for your own multi-layer composite tubes. You might want to get some experience laying up hybrid carbon-Kevlar fabrics on a smaller project first.

You're going to need serious consideration of the motor mounts. I would suggest open mounts, without tubes. Machined aluminum centering rings come to mind.

Hey... You brought up the four-by-N5800C* idea. Need to keep 'em in the a/f. CDX from your local Homer's de-pot won't get you a cigar. And I don't know that I would trust threaded inserts to hold back 4 N5800's. The rear c/r is going to need a flange against the rear of the a/f tube. I'd probably go with a complete motor mount unit, full stack c/r to c/r, to slide into the a/f, then install radial screws in both front and rear c/r's.

Holding on to ~5 tons of thrust... This is not for the faint of heart.

Please... Let us know when you're gonna fly this beast. I wanna see this.
 
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I think it's do-able. Just gotta build it right.

Machine the c/r's to take the motor cases without mount tubes. Thin-walled aluminum tubing between the c/r's, all held with 4 lengths of all-thread, and a 4 point star retainer that bolts to the rear ring. Slide it into the a/f tube, and install multiple rows of radial screws.

Build it right and it'll hold. Build it wrong, and people gonna be diving for cover.

Saw that happen once already. 4-by-98mm mount made of home-improvement-store plywood, in a 36" sono-tube a/f. The first time he tried it with two M1419's. Only 1 lit, it raised up off the rail, and fell over, flat on the ground. A year later, he put 4 L1500's in it. That time it ripped off the pad. But at about 300 feet, the mount gave up, and we had 4 L motors going in random directions. One found the windshield and dashboard of a brand spanking new Dodge pick-up that had less than 800 miles on the odometer. It wasn't pretty. Or cheap.
 
I am building my Cherokee-N with 10.25" dia. Sonotube. On the airframes I am doing two wraps of 6 oz. fiberglass outside and 3.4 oz. on the inside. For the couplers, I'm doing the opposite. Key of course is 1) picking very consistent sized tubes (including stripping the semi-waterproof protective wrap very consistently) and cutting/building your couplers undersized to accommodate for laminating.
 
Mach+ != Sonotube

There is too much inconsistency and imperfection in Sonotube to consider building a supersonic rocket around this material. On top of that, it is exceedingly heavy for its size.

I have worked with Sonotube a lot and it is fine for dumb heavy rockets. I would never consider using it for the airframe or even a mandrel for an airframe for a rocket going supersonic.

I could go on, but it isn't worth it. Suffice to say, you can't do Mach 2+ on the cheap - you're just designing a safety hazard, IMO. You need high-quality, smooth and perfectly straight airframes. Period.

--Lance.
 
llickteig1 said:
Mach+ != Sonotube

There is too much inconsistency and imperfection in Sonotube to consider building a supersonic rocket around this material. On top of that, it is exceedingly heavy for its size.

I have worked with Sonotube a lot and it is fine for dumb heavy rockets. I would never consider using it for the airframe or even a mandrel for an airframe for a rocket going supersonic.

I could go on, but it isn't worth it. Suffice to say, you can't do Mach 2+ on the cheap - you're just designing a safety hazard, IMO. You need high-quality, smooth and perfectly straight airframes. Period.

--Lance.
Click to expand...

Yep! I was going to use Sonotube for my L3 shot, But went with the 5.5 Bluetube which was far cheaper than Buying the required epoxy to laminate the sono.
 
Ok, I'm getting signals that while it might be possible to push 10" Sonotube to Mach 2, it's not really the best choice of materials. I'm not married to it. So, I'm open for suggestions. Any recommendations as to what would be up to the challenge? Is this something that I can buy off the shelf, or am I forced to make it myself (like the carbon/kevlar layup), or finding/creating a suitable mandrel for my design goals?

Oh, on the Crazy (Well, maybe not so crazy) side of things, there is the idea of building this much like burkefj's foam rockets, without worrying about the speed and altitude aspects. Which may or may not use a cluster but wouldn't be intended to go very fast or high.

What I want to do is make a very large B@D@$$ looking rocket that could be flown SAFELY. I want to have fun with this, not hurt anyone (bruised egos aside), or damage anything.

The important thing to remember, by asking these questions, I'm learning something, and hopefully, others are too.
 
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K'Tesh said:
Ok, I'm getting signals that while it might be possible to push 10" Sonotube to Mach 2, it's not really the best choice of materials. I'm not married to it. So, I'm open for suggestions. Any recommendations as to what would be up to the challenge? Is this something that I can buy off the shelf, or am I forced to make it myself (like the carbon/kevlar layup), or finding/creating a suitable mandrel for my design goals?

Oh, on the Crazy (Well, maybe not so crazy) side of things, there is the idea of building this much like burkefj's foam rockets, without worrying about the speed and altitude aspects. Which may or may not use a cluster but wouldn't be intended to go very fast or high.

What I want to do is make a very large B@D@$$ looking rocket that could be flown SAFELY. I want to have fun with this, not hurt anyone (bruised egos aside), or damage anything.

The important thing to remember, by asking these questions, I'm learning something, and hopefully, others are too.
Click to expand...
Low speed and low altitude with large clusters is very do-able with Sonotube, but that wasn't the original query. Keep the rocket under 600mph or so and cut your altitude expectations waaaaay down and you're in the realm of big Sonotube rockets.

See here: https://www.rocketryforum.com/showthread.php?130181-KloudBuster-MAX-Cluster-P-Project

Low and slow, huge rockets are really fun and a true challenge. Bring plenty of $$$ and helpers.

--Lance.
 
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If you want large and fast bring your money. Create a mandrel, use lots of cloth and epoxy to make custom tubes, build large curing oven.

The other possible option is to talk to Performance Rocketry/ Rocketry Warehouse. I am fairly certain that is where Wildman got his 11.5"-12" g10 tubes for the Mega Darkstar.
 
Sonotube is designed to handle a 20+' column of wet concrete. It's plenty strong. It's bursting strength from internal pressure is over 300 psi,

Goto the sonotube website and download the mechanical specs. You might be surprised.

Obviously money is not a problem as the cost of (4) N5800 is not cheap. The peak load is ~7200 pounds, so how you attach the motors/rings to the airframe may be the limiting factor. You have a shear load of ~250 pound per linear inch of the 10" (4) motor flange ring.

If you use a top, middle and lower ring with (4) motor tubes bonded into a monolithic structure to distribute the thrust load, I don't believe the motors will fly up through the airframe. The issue IMO is will the tube fail by column buckling and/or compressive failure.

https://www.sonotube.com/products/sonotubeconcreteforms.aspx

What is not clear is the wall thickness or the published strength of the material so you can determine the margins.

Bob
 
bobkrech said:
Sonotube is designed to handle a 20+' column of wet concrete. It's plenty strong.
Click to expand...
Compressively I'm sure it is. I'd be much more concerned about side loads from aerodynamic forces and any asymmetric thrust. Most of the airframe failures I've seen in high mach flights have looked like tube delaminations from bending moments.
 
Most tube failures from compression probably are caused by the same phenomena, that caused aircraft such as the B-58 Hustler to to have a Coke bottle shaped fuselage ( when viewed from above), the compression would cause a side load on the tubing and collapse it. Then again I may be way off base.
 
K'Tesh said:
Remember, I have no idea if this is possible or not, nor do I know the costs involved... The sim is calling for 4xN5800-CS-P, and has it going at Mach 2.06 to 25,898'.
Click to expand...

If you can afford 4 N's, then you can afford to get sometime better than SonoTube!!

A lot of people have made big and powerful rockets out of Sonotube. I would bet that most of then had a layer or 3 of fiberglass lamination over the top.
 

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