Anyone Modify a PML Tethys for Dual Deployment?

[Rob Campbell]

I just bought a PML Tethys. I would like to fly it on K motors. Has anyone modified a Tethys for altimeter controlled dual deployment? Any tips are appreciated.

 

[Steve Shannon]

I didn’t own a Tethys, but I modified similarly sized PML rockets using their CPR3K system.
Their instructions made it easy and that’s really how I learned dual deployment.

 

[DAllen]

That might go mach+. There used to be a disclaimer on the PML site cautioning fliers to keep unreinforced QT to under 0.8 mach as I recall. I can't seem to find that same disclaimer on the LOC site.

Edit:

Here is the disclaimer

 

[Steve Shannon]

That might go mach+. There used to be a disclaimer on the PML site cautioning fliers to keep unreinforced QT to under 0.8 mach as I recall. I can't seem to find that same disclaimer on the LOC site.

Edit:

Here is the disclaimer

I’ve flown QT rockets over Mach. The weak point is the phenolic couplers. They snap when the QT flexes.

 

[hartlch]

I just bought a PML Tethys. I would like to fly it on K motors. Has anyone modified a Tethys for altimeter controlled dual deployment? Any tips are appreciated.

I modified an Endeavor for zipperless dual deploy. I used the existing tubing and it ended up being a little cramped for the chutes I have. I also have a Thethys and believe you would have to lengthen it to be able to do DD. And I don't use the piston in the Endeavour. PML had some sheets listing all their rockets and suggested enhanced construction considerations over a wide range of motors. I'm not sure if you can find that document any more since they were acquired. You probably need to beef up the fins if you are going with a K motor. I didn't use anything special construction-wise on mine. I do use Aeropoxy adhesive and have very good results with the QT tubing.