Third Charm's The Try | A Minimum Diameter M Project

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Some folks may be aware that I've been occasionally putting together a YouTube video where I build a rocket using only JB Weld for bonding. I did an I500 that was mostly successful and a K455 that came in ballistic, but the fins survived!

Most recently, I decided to give it a go with a CTI M1675 using a tube and G10 sheet I had kicking around. No tip to tip. No fillet reinforcement. Just good composite bonding prep and careful construction. RASAero says 23,000 feet and Mach 2.2. The youtube video will be out on my channel on May 5th, but I wanted to share some build photos!

I started by cutting the fin slots off a longer 3" G10 tube I had and it left me with 33.5". Incidentally, that's just about perfect for a 75/6400 case. I set it up so the coupler/electronics bay gets glued into the airframe and the motor case bolts to the bottom bulkplate. All recovery in the nose!

I also just threw a picture in of this piece of all thread that I rounded off because it came out very aesthetically pleasing.

 

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I freehand cut the fins with an angle grinder and a diamond cutoff wheel. Then, in a bold play, I eyeball beveled them with my belt sander. They came out more than good enough for who it's for.

I basically stole the fins from Kip's Mesos. If it ain't broke don't fix it. Plus, they're super simple and efficient with G10 use. That's great, because by the time I was done ruining them while trying to bevel them I cut 8 fins lol

 

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After probably an hour of ferocious sanding every bonding surface, I 3D printed a set of fin guides and got to work bonding the fins to the airframe with JB Qwik.

I don't have anything funny to say here. It went well.

 

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Annnndd now for the important bit. Big ol fillets. I degassed the JB Weld in a vacuum chamber before laying them out with 1 3/4" PVC.

 

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I have a thing for wanting my fillets to look flawless, so I lightly sanded the structural JB Weld fillets, added a layer of West System with 410 filler and sanded them smooth, then hit them with primer.

This is where I decided I wanted to paint it despite the penalty in altitude. Effectively, the point of this project is to get a practice run on high alt deployment techniques before I move on to a couple of N motor projects I've got in the oven. So, deciding to overdo it if I'm going to do it, I went with a nasty heavy glitter flake from Rustoleum with a ton of clear coat over top of it knowing full well that sending it past Mach 2 was going to undo all of that effort.

 

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For recovery, @bandman444 designed me a 3D printable sled for two stratologgers and a Featherweight GPS transmitter.

Using a single shock cord, I put the drogue near the NC and the main chute attaches directly to the top of the electronics bay via a 1/4" lifting eye. I decided to give the ol Jolly Logic Chute Release a shot for my main.

For the charges, I made cannons from copper fittings. BP goes in, a little paper towel/tissue paper/wadding, a 3D printed "biscuit" for a nice flat surface atop the charge, and then sealed with GE Silicone II. 1G primary charge and 2.25g hail mary backup. I want that motor case back.

For those curious about switches; there aren't any. Twist and tape, baby. If I had room for 9 Volts in there you KNOW I'd be using those, too.

 

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annnnnddd here's your cliffhanger

Amazing photo as always by Shane of rocketrypics.com

Big thank you to @Neutronium95 for letting me use this awesome tower at FAR!

 

[Flare]

What a gorgeous motor. Flame to rocket ratio is also excellent. Great build Braden, looking forward to seeing the video.

 

[WFWalby]

I freehand cut the fins with an angle grinder and a diamond cutoff wheel. Then, in a bold play, I eyeball beveled them with my belt sander. They came out more than good enough for who it's for.

I basically stole the fins from Kip's Mesos. If it ain't broke don't fix it. Plus, they're super simple and efficient with G10 use. That's great, because by the time I was done ruining them while trying to bevel them I cut 8 fins lol
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Very nice project! Where did you obtain Kip's fin template? Would you mind sharing?
William

 

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Very nice project! Where did you obtain Kip's fin template? Would you mind sharing?
William

No template. Myself and @tjsnakez just took note of how Arcas-esque they were and went from there. Not really much of a template is needed there. Basically just taking a rectangle and cutting a 45 across it, haha

 

[THarrison]

Sweet picture! What was the final altitude? Did it recover successfully?

 

[ECayemberg]

Hey Braden! This is really freakin' cool! Beautiful project; looks like it goes from sitting still to M2 in no time flat...in several ways!

Highlight of the thread...is definitely the beveled all-thread!

Great stuff!!!

 

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Sweet picture! What was the final altitude? Did it recover successfully?

I have to maintain SOME mystery until the video is posted, right?

I WILL leave you with this

Hey Braden! This is really freakin' cool! Beautiful project; looks like it goes from sitting still to M2 in no time flat...in several ways!

Highlight of the thread...is definitely the beveled all-thread!

Great stuff!!!

Thank you, I worked very hard on that allthread. Hahaha.

It definitely didn't waste any time getting out of there.

 

[pugachu]

Looks like the rocket came down nicely, and the main parachute refolded itself into a nice, tight burrito on landing!

 

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Looks like the rocket came down nicely, and the main parachute refolded itself into a nice, tight burrito on landing!

It landed in a rather cumbersome bit of sagebrush and I didn't want the breeze to tear my brand new thin mill chute. I already ruined one in ground testing.

I'm glad you didn't assume the main didn't come out like others have, though! Haha

 

[Aeva]

It landed in a rather cumbersome bit of sagebrush and I didn't want the breeze to tear my brand new thin mill chute. I already ruined one in ground testing.

I'm glad you didn't assume the main didn't come out like others have, though! Haha

Why not use something other than your nice chutes for ground testing? I ruined a chute doing the same thing, and now I put about the same amount of surface area in paper towels wrapped in the nomex blanket. If it burns, that's a good visual indicator that I packed it poorly or need more protection, and I don't lose an expensive part.

 

[jmasterj]

Why not use something other than your nice chutes for ground testing? I ruined a chute doing the same thing, and now I put about the same amount of surface area in paper towels wrapped in the nomex blanket. If it burns, that's a good visual indicator that I packed it poorly or need more protection, and I don't lose an expensive part.

Because if you're not testing the same configuration that you're flying, what's the point?

 

[Aeva]

Because if you're not testing the same configuration that you're flying, what's the point?

Why not have a spare chute for testing only then, as opposed to a new one? Paper towels were just a suggestion I've done.

 

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Why not have a spare chute for testing only then, as opposed to a new one? Paper towels were just a suggestion I've done.

Well, that's how it ended up working out. Just not intentionally lol.

I started with a standard thickness chute and realized I needed a tighter packing solution.

I'll still fly the burned one lol

 

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Here's a short of the boost portion. The full build, flight, and recovery video willl be out next weekend.

 

[WFWalby]

Here's a short of the boost portion. The full build, flight, and recovery video willl be out next weekend.

Great flight. That is some of the best tracking smoke I've seen. What motor? First post states a CTI M but the pic shows a "DrRocket" looking case. Please set me straight. Thanks

 

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Great flight. That is some of the best tracking smoke I've seen. What motor? First post states a CTI M but the pic shows a "DrRocket" looking case. Please set me straight. Thanks

It's a CTI M1675 loaded in an Aerotech case. Most of the 75 and 98mm loads are cross compatible.

 

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Here's the full build, flight, and recovery video!