24mm MMD Machbuster

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Think this will break mach??

  • Yes

  • No

  • posibbly if done right

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B

ben

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i have been eyeing my BT-50 for a while and I finaly decided to do something with it. I am going to make the fins out of 1/8" 3-ply midwest wood. I will be getting a basswood nose cone I will soak in CA. I will use Estes shock cord and a 12" Estes chute. I don't know of you have noticed yet but this is going to be something made form "left over" parts and things I have laying around. I will gloss and polish this rocket like crazy to make it smoooooth. I plan on breaking mach on a G37. I thinking about making it so I can add a small altmiter to se my altitude and if I broke mach :D I am going to post pics and dimensions as soon as I figure them out :p ;)

thanx, Ben
 
The G37 probably doesn't pack enough punch to get that rocket to Mach 1, but you will get some incredible altitude (over a mile). If you are really bent on making something that breaks Mach I would suggest making something in the 29mm size. Then you can use a G80... or a G125 if AeroTech reintroduces it; which they said they might do.
 
I am aware of things I would like to break mach but I also just want to make a fast, high altitude rocket :D :D

thanx, Ben
 
look at my sig... "2 years till L1 WWHHHOO!!!" so maybe in 2 years. I am thinking about making is so all it does is lawndart :p I will use no recovery to save space, and make a nice landing :D ;)
just kidding maybe I will just make it a high alt rocket and go as close to mach as I can eventually hit it if the conditions are right

thanx, Ben
 
Have a L1 sign your flight card. I fly can fly Js and Ks and I'm 15. My friend is 14 and he does Ms.
 
Originally posted by RocketboyG80
The G37 probably doesn't pack enough punch to get that rocket to Mach 1, but you will get some incredible altitude (over a mile). If you are really bent on making something that breaks Mach I would suggest making something in the 29mm size. Then you can use a G80... or a G125 if AeroTech reintroduces it; which they said they might do.
Click to expand...

Now here's a design I whipped up last night just for funsies, and RockSim v8 says an Aerotech G55 will push it up to around Mach 1.7 :cool: . I'm seriously considering trying it out after I refine the design somewhat; I'm not quite satisfied with the fins. The design is a minimum-diameter 24mm 3FNC with a streamer and a parabolic nose cone.

Later this evening I'll try to post a picture for those who don't currently have RockSim.
 
i built a similar 24mm MD rocket that uses airfoiled 3/32 5 ply birch fins, an Estes Nosecone, and a kevlar/streamer recovery system. it has a 18" section on BT-50. I used epoxy throughout construction and it has 3/16" launch lugs. according to rocksim it should get to about 4000 feet and 725 mph (~mach .95) on an F21. On a G37 it reaches 6700 feet at mach 1.2 but I am absolutely sure it would shred at that speed.
here is a picture of it, it is called Sky Warper
 
Originally posted by TWRackers
Now here's a design I whipped up last night just for funsies, and RockSim v8 says an Aerotech G55 will push it up to around Mach 1.7 :cool: . I'm seriously considering trying it out after I refine the design somewhat; I'm not quite satisfied with the fins. The design is a minimum-diameter 24mm 3FNC with a streamer and a parabolic nose cone.

Later this evening I'll try to post a picture for those who don't currently have RockSim.
Click to expand...

... and here they are. First, the 2D drawing.
 
Originally posted by outasight13
i built a similar 24mm MD rocket that uses airfoiled 3/32 5 ply birch fins, an Estes Nosecone, and a kevlar/streamer recovery system. it has a 18" section on BT-50. I used epoxy throughout construction and it has 3/16" launch lugs. according to rocksim it should get to about 4000 feet and 725 mph (~mach .95) on an F21. On a G37 it reaches 6700 feet at mach 1.2 but I am absolutely sure it would shred at that speed.
here is a picture of it, it is called Sky Warper
Click to expand...

suggestion: mach .95 bad... go faster or slower, dont stay near mach. going through dose bad things. once your past it, its smooth sailing..
 
Originally posted by TWRackers
... and here they are. First, the 2D drawing.
Click to expand...

at mach those fins are gonna schread... think small and aerodynamic if your going that fast.
 
Originally posted by metalwizard
at mach those fins are gonna schread... think small and aerodynamic if your going that fast.
Click to expand...

That's what has me worried. I had to make the fins big enough for stability, but they can't extend too far forward up the body tube or they intrude forward of the CG and make the stability worse; it's already marginal with a relatively short body and a long motor. Like I said, I just whipped that up quickly last night, and I need to spend some more time refiningthe design until I have something that's stable, has a low enough Cd, and has less wussy-looking fins.

You don't see it in the drawings, but you would in the RockSim file: the fins will have an airfoil profile. Should I consider a more diamond-like profile, like the fins on a Nike Smoke?
 
are there 3 or 4 fins? If only three maybe you could add a fourth and make it shorter? thank you for the design though I am kinda looking at making to look like the Black Brant II, I want that style nosecone and I like the fins on it, you could make them like the other pic above just square at the bottom, I will make it painted like the BBII that will look neat. Just a thought, looks good and thanx for the help guys I don't have rocsim YET ;) hopefully B-day money will end that :p

thanx, Ben
 
Here's the fins on my 29mm min. dia. rocket. Most people would agree that triangle designs like this one are the most shred resistant; in this case the most resistant to being pulled off of the rocket, since they are made of 1/16" G10 fiberglass.
 
These are the rockets I've buily more of than anything.
I just have a thing for small and real fast rockets. The problem
I had was keeping the motors in when the deployment charge
went off. I sure have lost quite a few 24mm cases and 29-100 also. I know most people dont have the use of a metal lathe.
So they cant turn a retainer. But if you not going to use a 24/40
case. Then thats not a problem. I'll start by glassing the tubes.
I always glass my rockets. Got it where I can throw two wraps.
of 4oz. on a rocket now and keep them lite. I've used 1/8plywood
in the past but now I use 1/16" G-10. They will go faster with thinner fins. the nose cones I'll cut the shoulders Down where it's only about 1/2" then I drill holes around it with a small drill bit.
Then I cut a small pice of tube from the lenght of tube thats been glassed. And use JB-quick weld to glue it. Use the coupler stock from balsa machine. This way I can use a bulkhead with a small I-bolt. Makes for a better fit. Than the estes way of hooking up the
shock cord. If you can get a spent motor case, You can cut a small lenght. And use it for the motor stop and glue your shock
cord to the inside of it. Dont use CA-glue. Sets to fast I use the JB-weld to glue the fins on it holds real good and you dont want big fin filets. It would just add extra weight. Hope this gives you guys. Some Ideas on a few things. I'll just add some pictures of a few things from the machbusters.
 
This one is a BT-50 with 1/8" airfoiled fins. weight with out motor
and chute is 4.1 oz. Rocsimms says 836mph. And a half mile in 3seconds
 
this one you can see how I added the lenght of body tube to the nose cone. Should be a fun rocket right now it's 2.4 oz.
 
Try an old aerotech G-110 . Ive built minimum diameter rockets for this motor in the past. And it rocks.
 
MaxQ said:
Guess he would say something like:

"I'm not JRL1 and don't plan to be.."
Click to expand...

Correct! Untill TRA allows a JRL1. I am done with NAR. I will buddy fly.

Ben

P.S. I amnot going to explain why.
 
explain...don't think you need to.

The value of JR L1 has been debated quite a bit...some feel there are some bragging rights associated with it...but it is buddy flying for all intent and purpose...but with some additional limitations.
 
ben said:
Correct! Untill TRA allows a JRL1. I am done with NAR. I will buddy fly.

Ben

P.S. I amnot going to explain why.
Click to expand...

I thought TRA didn't have any age limitations for certifications.
 

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