# Supersonic on a G?

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#### BlueNinja

##### Well-Known Member
I've been thinking (maybe a little too hard) about making a mach buster. I'm not old enough to do L1, don't know anyone that would fly an H for me, but I'm on a budget high enough to buy Gs. Would it be possible to go supersonic on a G or would I have to find someone with an H to fly?

#### Ryan S.

##### Well-Known Member
I think it is. G80 and G104 would be great for that, though I would use a G80 so as not to risk the casing

I once read a story of a bunch of guys that raced their mach busters on G80s. When they found them, the balsa nosecones had been torn apart because of the speed the wind was flowiing over them. They weren't pushed into the BT but it was like they had been picked apart. Very cool

#### jflis

##### Well-Known Member
You can break mach with a G. I've seen it done with an F/E 2-stage. **proving** it is another thing all together

#### n3tjm

##### Papa Elf
G125 all the way .

Man, I miss those 24mm Vulcan Systems G200's

#### teflonrocketry1

##### Well-Known Member
The Rocket Vision Mach Buster rocket has an ABS plastic nose cone with a phenolic body tube and G-10 fiber-glass fins. This design is very rugged. I can say this from experience since I shovel recovered mine a few times with flights on much smaller motors. The design flies great on C6-5 motors.

The 2.5 ounce, 13 inch long rocket easily does Mach 1.5 on a G55 motor and Mach 1.1 on an F72 motor. The problem is finding it afterwards, the G55 flight sims to over 1 mile AGL! It was once reported that there was only about a 30% chance of recovering the model from these supersonic flights.

Bruce S. Levison, NAR #69055, Rocket Vision's #1 Ask An Expert

#### BlueNinja

##### Well-Known Member
Alright, this will probably be my first scratchbuild, need to get the flying tube off my mind. I would probably need fiberglass, after hearing the balsa nose story. Minimum diameter, small fins to reduce drag, what else?

Definitley SU motor. My budget's high enough for a couple of Gs but not for a couple of cases.

#### RocketboyG80

##### Well-Known Member
I recently submitted a review of a mach buster I built to EMRR. If you read it, you will see I made a cheap one and a more expensive one. The expenisve one uses a PML 29mm tube and PML 29mm nosecone with 1/32" G10 fins. The cheap one uses a LOC 29mm tube and an Estes BT-55 nosecone (I cut it down to the correct size and attatched an Econojet spacer for a shoulder) with 1/32" G10 fins. They both fly great; especially on G's. EMRR

#### BlueNinja

##### Well-Known Member
Cool! May I request permission to build that design?

#### Neil

##### Well-Known Member
OK. I gotta chime in. The Hawk Mountain Raptor can do mach one on an H125, but you said you couldent do that... I hear a G125 could do it. And heres a review for my Mach Buster 1. I encourage you to build one of those. Also look at the Performance Rocketry page and see about buying a 29MM fincan. Those are cool. I havent got one yet, but I will soon. I need another 29MM mach buster. MB1

That ones cool. It can do mach 1.75 on a J570W! It can also fly on as little as an F20-4W!

#### BlueNinja

##### Well-Known Member
I just may be able to find someone, our club president is (i believe) L2, but I don't want to use somebody else's motors for this. I'll try your design.

#### Tallman

##### Well-Known Member
LOC motor tube is strong stuff - a bit sturdier than the stuff Red Arrow sells and BMS' "BT-50 HD". Basswood/thin plywood is likewise plenty strong (at least when soaked in CA) and the MB fin shape itself is small and very stiff. Try it! These things are hard to recover (less so out here in Calif. on dry lakes) and G-10 plus glassing isn't necessary and significantly lessens top speed due to weight.

#### Neil

##### Well-Known Member
Coooooool! I wanna try that once I have the money....

#### DPatell

##### Well-Known Member
No flights on my 29mm Mach Buster, but the 24mm Machbuster is doable. Mine had 1/8" balsa fins with 1 layer of 4 oz glass fin to fin, and 0.75oz on the body tube. Flew amazing on an F101, but CATO'd on an F72. I doubt it would even need the fiberglass.

#### rstaff3

##### Oddroc-eteer
HiflyinPRguy,

I built a machbuster type rocket using a BT-55 cone, but it took some trimming. I used a small piece of a 29mm SU casing as a replacement shoulder. It worked fine. Mine was phenolic, but glassing shouldn't be necessary on a short rocket.

Is the Giant Leap composite stuff a good choice? I forget what thicknesses it comes in.

Finally, before sticking a reloadable casing in it, remember this has a high probability of getting lost

#### Rocketjunkie

Originally posted by Neil
You gotta be kiddn..... No glass on a mach buster?????
A stock Estes Gnome will survive 1000 mph on a D40.

#### HiflyinPRguy

##### Member
rstaff3,

The nose cone is the only part of this project I have completed so far and I did it in the manner you suggested with a spent G80.

I haven't tried the composite board yet but I'll probably order some next week. I plan on either using the dowel/epoxy filling method or using wire and epoxy like my dad uses on his fishing lures. I might also order a Fireball for my 4" PE BullPuP

Glassing seems to be the lesser of two evils:

Glassing =More weight = Less Speed but more strength. I'll need the strength considering part of the tube will have to be ground away to fit the engine in.

No glassing = less weight but the rocket becomes a flying orgy of disintegration and destruction.

As an alternative to glass, I wonder what soaking the tube in thin CA would do?

#### BlueNinja

##### Well-Known Member
That would be a cool project... "How Low Power a motor can you break mach on?

#### Neil

##### Well-Known Member
D21-7T. 18MM minimum diameter. I have one that is mach capable on that motor. I need a tower launcher to fly it, though.