Rocketman Machfever

Rocketman Enterprises - Machfever

Contributed by Chan Stevens

Construction Rating: starstarstarstar_borderstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar_border
Manufacturer: Rocketman Enterprises
Rocketman Mach Fever

Brief:
Having gotten hooked on Cesaroni Pro38 motors, I started looking around for 38mm kits. This one immediately caught my eye. While I didn't get it anywhere near breaking Mach 1, I did find this rocket performs well on a range of motors and is a beautiful looking design. With its two sets of fins, it will really draw a few stares and possibly even some drool at the pad.

Construction:
The kit includes:

  • Plastic ogive nose cone
  • 2.7" Kraft phenolic tubing (10" payload bay and 29" body)
  • 2 sets of 4 pre-cut G10 fins
  • 38mm motor tube
  • Plywood centering rings
  • U-bolts for shock cord
  • Heavy-duty nylon shock cord
  • Brass launch lugs
  • Rocketman chute

This was actually fairly simple to build, though for some reason I always struggle with high power kit builds. For starters, most kits ignore motor retention including this one. I decided to use blind nuts in the aft centering ring, and bolt washers from the outside to keep my new Pro38 case safely secured. This took a bit of drilling, grinding, and epoxying first then I was ready to start the normal construction.

I also find that HPR kits tend to be fairly light on instructions and illustrations. This kit again was typical. Still, there was sufficient information for the experienced builder to get through with a bit of caution. Construction starts with epoxying the centering rings to the motor tube. This was only my third HPR kit and I tacked everything in place exactly to the dimensions, only to scratch my head afterward and wonder whether the rings go to the forward edge, aft edge, or are centered on the marked lines. As it turns out, the dimensions in the instructions didn't quite match up to the pre-slotted body tube dimensions, so I had to do a considerable amount of rework with my Dremel to get everything to fit.

I will never again build a pre-slotted tubing kit without first dry-fitting fins and centering rings then tack them in place. I will also go much lighter on the epoxy fillets since the fins mount flush to the motor tube.

The nylon shock cord is then epoxied to the motor tube and the finished assembly is epoxied inside the motor tube. After everything has cured, the fins are then epoxied on. I'm still getting the hang of mixing epoxy and pouring good fillets, but the finished fillets on this one turned out fairly well. I then sanded the fillets down with 120 grit wrapped around a 18mm dowel.

The payload assembly consists of a 10" tube, a tube coupler, and a plywood bulkhead. The bulkhead gets a U-bolt for attaching the shock cord. I coated the coupler with CA, then sanded it back down smooth to make sure it would not swell when exposed to humidity.

I decided not to go with the brass launch lugs, opting for rail buttons instead. Our club has a nice 6-foot rail and I find it's much better than a rod for larger rockets, plus the buttons are lower profile and lower drag.

Finishing:
There are no "stock" paint schemes referenced for this, though the picture on the auction site I bought this from showed a very nice white/orange scheme. I had just picked up some Krylon anodized paint though and was looking for a bird to try it out on. After filling spirals with Bondo and applying 3 coats of primer, I went with a blue anodized base. I then masked off the blue and used a gold metallic spray for the fins and the nose. The result was a fantastic finish and one of the best looking paint jobs I've managed to pull off. There's also a very nice peel 'n' stick decal supplied with this kit, sporting the Mach Fever name and the head of an eagle.

Construction Rating: 3 out of 5

Flight:
First flight was on a picture perfect day: clear skies, high ceiling, and barely a trace of wind. I chose to start off easy, using an H153 and 8-second delay. The delay adjustment tool is one of the things that drew me to Pro38s--no more swapping out delays on the field and no risk of using the wrong spacer/delay grain.

This rocket raced off the pad and in the blink of an eye my $30 motor had gone up in smoke (that's why I mainly stick to low power). The flight was absolutely perfect, with just a touch of roll due to my less than perfect fin alignment. The 8-second delay proved to be a bit late and will be using 6 seconds of delay next time.

I had loaded a Pico-alt micro altimeter in the payload bay, which read 1707 feet. That puts this at a very draggy 1.1 drag coefficient, but I wouldn't change a thing on those beautifully swept fins.

Recovery:
The Rocketman chute is a wonderful chute. It is made of very heavy-duty nylon and the strongest cords I've ever seen. I'm not sure there's a rocket out there than can outlast one of these chutes. They also look great with multi-colored panels while drifting down. I recovered everything with no damage at all.

Flight Rating: 5 out of 5

Summary:
With high power comes high price and that is about the only con I can come up with on this other than the minor annoyance of centering rings not lined up.

The pro's would be the graceful lines and appearance of this kit and the flexibility to handle anything from a G to a J, which still might not break Mach 1 but could probably break a mile. It's also rugged enough to handle both L1 and L2 cert projects.

Overall Rating: 4 out of 5

Flights

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