Convert PML Tethy's to dual deply

[askrob]

I'm working on converting my PML Tethy's to a Dual deploy. I built it with the piston ejection. Any advice where to put the charge for the drogue shoot? Should I try to remove the piston? Should I keep the charge at the bulkhead, or figure out a way to get it below the piston? How would you convert a piston ejection to dual deploy?

 

[hartlch]

I built a PML Endeavor to dual deploy. I have a Tethys, but kept it stock. For the Endeavor, I figured out what the longest motor I would fly in it and split the body tube such that it would fit. I built the fincan using zipperless design. The piston takes too much space, especially in the Thethys, so remove it. Buy a coupler and bulkheads for the electronics bay. Model it in Rocksim or the like to see if everything will fit. You might need to get a longer chunk of body tube to fit your main chute+deployment harness stuff. It's going to be tight with the Tethys.

Chuck

 

[askrob]

Thanks. I'll cut the piston out and attach the shock cord to the strap that's attached to the motor mount.

 

[loopy]

Thanks. I'll cut the piston out and attach the shock cord to the strap that's attached to the motor mount.

This would be my thought as well. Keep it simple.

 

[rjenkins133]

I built a dual deploy tethys and did not use the piston.

I nearly doubled the total length of the rocket as well. - called it the "Stretch Tethys". I used it for my level 2 certification (many years ago).

Just another data point to confirm your decision...

 

[Steve Shannon]

I'm working on converting my PML Tethy's to a Dual deploy. I built it with the piston ejection. Any advice where to put the charge for the drogue shoot? Should I try to remove the piston? Should I keep the charge at the bulkhead, or figure out a way to get it below the piston? How would you convert a piston ejection to dual deploy?

PML had instructions (even kits) for how to convert their kits to dual deployment using their CPR (close proximity recovery) system.

 

[askrob]

All, thanks for the help. My Tethy's is shorter due to a crash a few years ago, but I have successfully converted it to dual deploy. It's got a 3.18 calibration empty on OpenRocket. It has a 3d printed nose cone with a metal tip that comes from one of my Wildman kits. So, it's head-end deploy. It's got dual deployment, so two separate altimeters (eggtimer proton and eggtimer quark) and GPS (eggfinder mini).