29mm motor retention...

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Stones

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I'm about to do an upscale of the Phoenix and will be using LOC BT, NC, and CR's. I'm going for the t-nut and some sort of clip motor retention method. I will be using RMS and SU motors. 29mm up to and including H impulse.
Here's a few questions I have for the masses....
Is there a specific rule of thumb on how far to space the t-nuts(#6) from the center of the MMT?
I will more than likely make seperate clips for each of the RMS and SU applications.
Should I NOT install a motor block in the MMT?

tia...
 
Stones,
On all of my NON Aerotech kits and scratch builds, I do not install an engine block. RMS, of course, have the thrust ring built in to the aft closure. On single use, I make a ring on the aft end with masking tape, built up enough to equal the outer diameter of the mmt tube. For retention, I use #8-32 Tnuts, mounted as close to the mmt tube as I can get them. For clips, I use utility hooks. They are easy to shape to what ever you need, and hold very well.
 
That pic I posted shows the wrong hook! I don't know where I got those from (they might belong to the wife). The one shown, has a knock out for using larger screws. The ones I use, look identical, but don't have the knock out on them. I'd be afraid the knock out would break loose on ejection.
 
Hint - fill the t-nut or blind nut with Vaseline to protect the threads from epoxy before you glue them in place.

I used three #6 blind nuts on my 29mm PML Explorer - see photo attached.
 
I have found that you can do a lot with coat hangers. I use them alot for motor clips. I have used them in many different fashions. I do a flat U shaped one that was described I think in Sport Rocketry for min-diameter rockets where you tape it on.

The wire from hangers is easy to bend and cut but is still strong, I used it on my L1 rocket.

Scott
 
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