Contributed by Tyndall Epps
The instructions for this kit are very complete and easy to follow. Even a person with limited experience building high power rockets should be able to handle this kit. Drawings are included and are clear and easy to understand.
The parts of this kit fit perfectly the first time. I did not have to sand a single piece. I built this kit straight from the instructions with one exception. I had an accident while epoxying the upper ejection tube into the airframe, the assembly dropped and the airframe cracked and the centering ring set inside the tube. Result-- I had to order a new section of 54mm tubing from PML. (by the way I received it the next day via priority mail). Since this was a full 36" piece I decided to use the whole thing instead of cutting a 15" piece off. This resulted in a very tall rocket which is now probably over stable. I would not recommend this as a modification. Although it flew perfectly on a Kosdon J280 in 15MPH winds I will probably cut it back to the designed length .
The good features of this kit are the well fitting parts, the "dado slots" used for surface mounting the fins and the design of the CPR 3000 system. This is the 3rd minimum diameter rocket that I have built and the "dado slots" work great. They involve cutting slots about 1/4 to 1/2 thru the airframe and setting the fins in these slots. The only change I make to PML's instructions which tell you to epoxy them in place is that I set the fins with medium viscosity CA and then apply epoxy fillets to the joint. I have yet to lose a fin. On my modified VB38 the main chute separated and the rocket came down very hard on just a streamer and there was no damage to the fins.
The remainder of the construction is very straight-forward and does not need to be discussed here.
One feature that I have not mentioned is the piston system used to deploy the main chute and drouge. Being new to the hobby I asked a lot of questions at our launches at Whitakers N.C. We have a lot of very experienced people in this group and most of them recommend leaving the pistons out. I started to do just that but decided to try them anyway. (the only piece of advice that I have not used). The result - The pistons have worked great and I will probably keep using them . Like PML says in the instructions-- Just make sure they slide freely. They should fall out when the airframe is turned upside down.
Now for the bad part. I hate PML's phenolic tubing. It is too brittle, hard to cut without chipping, and has deeper than normal spirals to fill. About the only thing I would use this stuff for is as a mandrel for fiberglassing. I am not good at fiberglassing so I use Hawk Mountain or Giant Leaps filament wound epoxy fiberglass tubing for high stress applications. My next project is going to be an exact copy of this kit using Giant Leap's 54mm tubing and replacing the Nimbus fins with a 54mm Acme fin canister and flying on a K700.
Construction Rating: 4 out of 5
Flight Rating: 5 out of 5
Overall Rating: 4 out of 5
UPDATE 6/01: Just like to add a follow-up on the phenolic tubing. Apparently PML's phenolic gets more brittle with age. I went to Orangeburg for the June launch. I had the rocket prepped except for the motor and propped it up against the back of my vehicle while I went to purchase a motor. When I came back the rocket had fallen over and cracked the tubing in 2 places. Result- I took a hammer to the airframe pieces and cracked the airframe away from the CPR 3000 components and they are going in a all fiberglass version. Moral - Either fiberglass this kit from the start or better yet - start with all fiberglass tubing. PML - find a better grade phenolic.
What You Can Do