Ok, my Loc Vyper III bash begins...

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Dec 4, 2003
Reaction score
I planned to bash the Loc Vyper III kit I have to use a baffling system; however, the bulkhead assembly I ordered from Rocketmotion never arrived (ordered over a month ago, but R.M. almost certainly didn't have any in stock, and had to special order them themselves).

Therefore, I have decided to turn my own bulkheads instead. I bought some 3/16" aircraft plywood from the local hobby shop, and I have a couple of 2.6" coupling tubes that I've had sitting around for awhile that I can use.

The only problem with these coupling tubes is they are PML, not Loc. They fit in the Loc body tube, but they are a tad...loose. This is no doubt due to slight differences in the diameter of each company's products. The fit is close enough, however, that I think I can get a snug fit by building up a thin layer of epoxy on the coupler tube. I like the PML phenolic better, anyway.

These coupler tubes are 4.5" inches long...I was planning to cut one in half to use. However, these tubes are long enough to be used as a mini-payload bay as they currently are...at least for a simple transbeep I would think. I'm thinking now of possibly using the entire length of coupler and cutting bulkplates for both end, with a 38mm tube inside the coupler to hold a future altimeter. Meanwhile, both bulkplates with have eight 3/8" holes drilled around the perimeter, for the ejection charges.

I cut one bulkplate today; however, I measured wrong somehow. I made a pencil mark on the plywood on the ==inside== of coupler tube and set the bit diameter down to that mark...however, the resulting piece I cut turned out a little too small. Tomarrow I will make a mark around the ==outside== of the coupler tube, and turn a bulkplate of that diameter. This should make a plate that is slightly too large, but I can always sand it down. Too large is better than too small.

When I turn the next bulkplate, I post pictures as well ;)
Very cool. Sounds like a fun mod.

May I recommend www.rocketguts.com for whatever rings you'll need? They offer quality work and products, and quick shipping! Just make sure, like with any custom work, that you give them SPECIFIC measurements!

I returned to plan A, which had me just making a baffling system instead of a full-blown payload bay, since I'm not planning on ever going duel deploy with this puppy (thats a ways down the road for me, still), and if I want just a simple altimeter or beeper on board (and I do), I would prefer to have it up near the nose.

So here are the baffling construction pics. This first attachment a few of the tools, and the 5-ply aircraft plywood I used for the main bulkplate...
In this next image, you see the ...um...second attempt being turned on the drill press using the "Carl Tulanko" tool (It was seeing this tool in Car's rocket building pics that inpired me to keep an eye out for a similar tool for myself).
The turning is complete, and the bulkplate is ready to have its outer diameter finely-sanded to fit snugly inside the PML coupling tube...
The bulkplate has been put back on the drill press, ready to have the baffle holes drilled in it...
Drilling the holes... the four 90 degree holes were drilled first, then the 45 degree holes in between were drilled. All holes are 3/8":
looking good so far,keep going!

I was always tempted to take the pilot bit out , but thought It would wander too much or grab ... looks like it worked out fine
good,I'm not afraid to try it now
Thanks :)

Heh, I actually have more pics, but a movie was coming on, and I figured I would post the rest now that its over :D

Here is this image is the finished bulkplate, sitting next to the cut PML coupler which has had a thin layer of epoxy applied to the outside of the tube to bring it up to the inner diameter of the LOC body tube. I test fit it and its snug as a bug in a rug now ;)

PS: I had the drill press set to the lowest speed, at 640 rpm. I think a faster speed without the pilot bit would have been...problematic :eek:
This next pic shows the assembly with the screw-eye in the bulkplate and the bulkplate epoxied into the coupler. The screw-eye also had epoxy added, to keep it from moving around and make that connection point even stronger.
Next, I sanded down a spare LOC centering ring I had on hand to fit the other end of the coupler. It became a little out of round in sanding it down that far, but this ring is only meant to hold in the steel mesh you see glued inside the coupler in this image, so a stong tight fit wasn't needed.

The steel mesh is the heavy ribbon kind like Aerotech uses, not this fine steel wool used for scrubbing pots etc.
Last, the retaining ring for the steel wool is epoxied in place, finishing the baffle assembly.

Wow, I actually really like what I came up with for a change...it looks cool :cool:
Dang, I should sell these...execept the little problem of the 3 hours of labor it took me to make this, and the fact that there would be maybe a maximum of five customers in the entire world :D

At any rate, I'll have to take a few days break before going back to work on the Viper III, in order to build a small rocket I promised for one of my Nephews.

Finsihed baffle assembly:
Here is a rocksim 7 of the modified Loc-Vyper III.

I changed the parachute position within the body tube and added a screw and washer the end of the motor mount tubes for motor retention. Nonetheless, I had to place baffling assembly just above the launch lug in order for the design to be stable.

Edit: An additional change I made was moving the motor mount tubes forward 1/2", thus moving the CP forward.