Mach 1 Rocketry Red Shift Build

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Simon Auty

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So completed AV bay.
Bulkheads are a fraction too wide for bay to slide into fuselage.
What’s the best way to bring the bulkheads into specification?
Can they be sanded down or do I need to grind them?
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David Schwantz

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Yes, looks good. Just when installing MMT make sure the glued shock cord is NOT inline with a fin slot. Also because of glue fillets around your CR's you may have to bevel the tips of the TTW fin tabs to get them to sit properly.
 

David Schwantz

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Sanding works. I happen to have a small bench belt sander, I just leave them assembled and sand to fit. I sand a slight bevel inward, so small you cannot even see it. But I do not want a body section getting hung up on the final edge at deployment.
 

tOD

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So when checking clearance of fins and recovery harness on the motor mount the tolerance is quite tight.
Not sure how to proceed, but here’s my current thought.
I’ve masked out the space for the recovery harness. This keeps it clear of the fins (just).
If I sand this masked space and epoxy the harness down here then I can get the fins in.
Is that how it’s done or am I missing something?View attachment 475352
That should work.
 

Simon Auty

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No progress to report this weekend.
Weather to cold for epoxying.
Contented myself with finding some #8-32 nuts for AV sled (2 short in kit from BadAss unfortunately and it’s pretty hard to find non-metric here in NZ).
And with sanding sled as it’s slightly too big for bay
 

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NateB

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Yes, drill straight through the AV band for vent holes for your altimeter and access to the switch. The instructions for your altimeter should note how big of a vent you need.

 

Sooner Boomer

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Your build looks great so far!

What I did to attach recovery harness to motor mount. I'm using a phenolic tube for the motor mount, but something similar would work for you. I tacked the harness in place with a few small drops of CA. I then soaked the harness in yellow glue., followed by a wrap of nylon cord which was also saturated in yellow glue. If this comes loose, thetre are other problems with the rocket!
A word of caution, CA can make kevlar brittle and can cause a weak spot that will break. Yellow glues and epoxy should not have this problem. You should be able to duplicate what I did (or make your own version) using epoxy.

01qharness.jpg
 

Simon Auty

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Looks good Sooner!
Due to proximity of thru the wall fins I can’t do the wrap idea although that looks to be a good solution.
Next step will be to place the motor mount into the body without obstructing the fins
 

Simon Auty

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So another question for all the experienced High-power builders here:

The kit comes with plastic rivets so do I use them to secure the forward tube to the AV bay and shear pins on the nose cone or the other way around?
 

timbucktoo

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The kit comes with plastic rivets so do I use them to secure the forward tube to the AV bay and shear pins on the nose cone or the other way around?
That is how most people do it, shear pins to NC and rivets to AV bay but I have seen it the other way on occasion. Also use shear pins on booster to Av bay.
 

Simon Auty

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Test fitting Jack Hydrazine conformal rail button backing plates.
Look good and more effective than a washer to distribute the forces transferring through the rail button to the fibreglass hull.
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Budro0

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Just look up conformal rail button backing plate on Thingiverse.
Jack Hydrazine has put a lot of files up including that one
He also posts them to r/rocketry on Reddit
 

Simon Auty

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Not much progress recently- waiting for some parts for nose cone AV-Bay
Cut this out of foam board last night to assist with getting fins on straight

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Simon Auty

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BadAss Rocketry Nose Bay arrived today including extra goodies (thanks Ian).
Can’t say enough about the help I have received from the crew at BadAss and Mach1Rocketry as well as you all here
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Simon Auty

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So next question:
I’m using West Systems epoxy
For external fillets do I mix it with microfibres or just let it go off a little to give the thickness I need to sculpt the fillets?
 

Banzai88

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So next question:
I’m using West Systems epoxy
For external fillets do I mix it with microfibres or just let it go off a little to give the thickness I need to sculpt the fillets?
16345142592683122766245060617342.jpg

My notes say 2 tablespoons per pump of resin for fillets
 

Banzai88

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