Brief:
The PML Matrix is a sport rocket advertised as a meteor defense weapon with a futuristic look about it. The kit is a 3” diameter model made for H and I high-power motors and uses a 3 fin configuration, although there are twelve fins total for the model.

Construction:
The kit came in a bag and included all the necessary parts; 3” diameter “Quantum” body tube (1/16” thick semi-flexible plastic tube), a 12” long payload tube section, nosecone, twelve G-10 fiberglass fins, bulkhead, piston assembly, ply centering rings, 38mm motor mount, 36” parachute, all the necessary hardware, a nice set of decals and detailed assembly instructions. The payload tube was dado-slotted for the six upper fins (not slotted all the way through) while the main body tube was pre slotted for through the wall main fins and dado-slotted for the long stabilizer fins. As usual, this is a typical high quality PML kit using some of the best materials available. Component Rating: 5 of 5

I used 15 minute epoxy throughout the construction, which gave me a little extra working time with the materials. Tip: Use 80 grit sandpaper for roughing up all surfaces prior to gluing; it has more bite than the recommended 120 grit and will create a stronger bond to the surfaces.

You begin by building the Motor Mount assembly. Once you have glued the black shock cord to the side of the motor mount tube, GLAZE the top of the strap with epoxy for added strength. Be careful not to install the mount with the strap area under a fin slot; position the shock strap area between two of the fin slots. Also, do not use the scotch tape method on the rear motor mount, as it just breaks off. Instead, push the rear centering ring on, then once the forward centering ring glue joint has set, use a 6” metal ruler through the fin slots to push the rear centering ring back out of the body tube.

PML uses a piston ejection system which works very well and eliminates the need for wadding. Once the piston assembly is built, glaze the inside and outside wooden surfaces with epoxy. This adds strength to piston and waterproofs the wood, so you can easily clean the rocket after the day’s flight. There is one problem to note; the PML 3” kits all tend to come with an oversized piston. I have not seen this problem with the 2” or 4” kits, but, right out of the bag, the 3” piston fits very tight inside the Quantum tube and requires a TON of sanding to get it to move smoothly. I have seen the 3” piston completely shred on an ejection with another friends PML kit, even though the correct powder charge was used. This was probably due to the fact that the walls of the piston were so thin from sanding it to fit that it couldn't withstand the ejection. I resolved the problem by purchasing a 3” PML body coupler tube as a replacement. The Coupler fits better and gave me the extra material needed to “Double” the wall thickness of the piston. I made a new Piston by cutting the coupler to the length of the original piston. Next, the wooden face was glued into the new piston following the directions from the instruction manual. Finally, I cut another “inside sleeve” from the remaining coupler material. The inside piston sleeve was then cut lengthwise and sanded at the cut area until it could be squeezed together and easily fit inside the original piston. This sleeve was glued inside the piston using epoxy and I made sure it was pushed all the way forward until it made contact with the inside wooden piston face. The final product was a very strong, double thick piston that works like a charm. Just something to try if you experience the same problem.

Next came the assembly of the bulkhead into the payload tube, however, there were two modifications that were made to the payload area. I used a 1 ½” U-Bolt instead of the eyebolt supplied in the kit because eyebolts have a tendency to eventually pull apart. See the picture for my U-Bolt installation. The other modification made was the installation of an altimeter bay. I already had a CPR 3000 ready rocket with mounts on my altimeter, so I just needed to duplicate the altimeter mounting bay for the CPR. I purchased two 3” x 1.5” centering rings, along with a 1.5” motor mount tube (38mm sized). The Motor mount tube was cut to a length of 6 ½” and a 1/8” wide slot was cut in the tube to a length of 1” so the altimeter could “breathe”. The two centering rings were glued to the motor tube; the top ring was mounted flush with the end of the tube and the lower centering ring was mounted 2 ½” from the other end of the tube. This assembly was glued into the payload section with the top centering ring recessed 4 ½” from the top of the body tube. Three 3/32” holes were drilled through the payload tube, which allow the altimeter to sense outside pressure. Finally, I inserted a piece of 1/2" hobby foam on top of the altimeter and used the nose cone for retention, since it is attached with screws. See the pictures for the altimeter mount and installation.

The lower fins were glued on next; I put a small amount of epoxy on the edge of a fin, then inserted it through the fin slot and used masking tape to hold it down on the motor tube. Once the three main fins were glued, I cut 1 ½” wide strips of 2oz fiberglass cloth to the length of each fin, then glassed the space from the motor mount to the fin to the inner body tube. I soaked the cloth in epoxy then folded it around a ½” wide stick, which allowed me to insert it into the tube. The stick was then used to make sure the cloth was pressed down on all surfaces. This adds strength inside the body tube area, especially where the fins are glued to the mount. Our club does a lot of cold weather launches, so I glass all my fins inside and out for added strength. Follow the directions for mounting the long stabilizer fins, which I installed after the lower fins were set. Once the stab fins are in place, glue the upper fins to the payload tube. Install three fins at a time, then turn the payload tube and re-use the main fins for alignment of the last three payload fins. Note: even though this kit has 12 fins total, the assembly was very easy. You don’t see many of these kits out there, probably because of the amount of fins on the model. Don’t be intimidated! It’s very easy to build and looks great when finished.

In addition, I fiberglassed the lower fins using 1 ½ oz cloth and 15 minute epoxy, then I applied small fillets to the upper and long stabilizer fins and larger fillets to the launch lugs and lower fins since they would be absorbing the majority of the shock from landing. Finally, three holes were drilled and tapped in the bottom of the model for the PMR motor retainer, a few drops of medium CA applied, then the threaded retainer plugs were installed. Construction Rating: 4 of 5

Finishing:
White Krylon primer was applied prior to the first sanding and I used 100 grit to cut away any excess epoxy resin left from the fiberglassing and to blend in the cloth seams. I used an electric sander in the glassed area, which helped cut the work down considerably. A few more coats of primer were added, then I wet sanded with 220 grit. Finally, a few more coats of primer were added and I started with 400 grit and finished it up by wet sanding with 600 grit. Dark Red Glossy Krylon paint was used on fins, while the nosecone and body tubes were done in Testors Chrome. The colors were picked by my son, Thomas, and I must say it really looks good once painted. It was a bit tricky applying the paint the way I wanted though; I knew the Chrome was very sensitive to touch, so I sprayed it last. The tricky part was masking all the fins after they were painted, but it turned out well. I used Testors Clear Glosscoat to protect the finish, since the chrome paint has a tendency to mar very easily.

Decals were not applied until later on and are not shown in the launch pics. As a last step, the shock cord and parachute were attached per the instructions. The 36” parachute deviates from the yellow/purple PML standard and is red/white in color, which I believed attributed to the color scheme decision. I did add a 1” link, which allows me to attach the parachute, then remove it later for cleaning. Don’t forget to tack glue the shock cord knots with a drop of epoxy as they can work their way loose. Finish: 5 of 5

Construction Rating: 4 out of 5

Flight:
My son and I went to the last launch of the spring season for our Tripoli Mid-Ohio Club. Everyone out there helped set up, then it was time to get some rockets on the pads. It turned out to be a beautiful day with temperatures in the 70’s with a decent, but manageable breeze. Our first launch of the Matrix was on a 38mm H123W with a short delay. The rocket was carefully prepared and placed on the pad. It was a real thrill seeing the look on my son’s face when he observed his first HP launch! The launch was spectacular for such a small load; It traveled a nice straight line leaving a really cool trail of white smoke behind.

Recovery:
The parachute ejected at apogee and the rocket drifted safely to the ground. The design of the long stabilizer fins on this model works well and the stab fins never touch the ground during landing. It was such a good flight that we had to do it again. We launched twice more, once on a I161W-medium and once on another H123W-short. Both flights went as planned, but the I161 really gets it off the pad in a hurry! On the final flight, one of the lower fins stuck in the ground like an axe during landing and was suspending the upper part of the rocket in the air. After checking the model for damage and realizing it was fine, it proved to me yet again that fiberglassing fins really pays off! We did get it a bit scratched up in the field, but nothing that cannot be touched up. That’s just rocketry! Flight/Recovery: 5 of 5

Flight Rating: 5 out of 5

Summary:
The PML Matrix really is an excellent model and, even though it has quite a few fins, it’s a dream to build and fly. The small modifications I made were only for my peace of mind as I want this rocket to last for a while. My only complaint is with the 3” piston; if they could only ship them a bit smaller in diameter, it would have been a perfect kit. I had not doubled up the piston yet, even though it was pretty thin. I did however buy an extra PML coupler from Ross at Magnum Rockets while we were at the launch and am in the process of doubling up the piston at the present time. That one fault aside, the Matrix otherwise is an excellent kit, good in quality and value, with one unique look that really catches your eye! Overall Rating: 4.75 of 5

Overall Rating: 4 ¾ out of 5