Rocketry Planet

February is the dead of Winter in Butte, Montana and that's the perfect opportunity to seek warmer climates.  Steve Shannon did just that, by planning a family get-away in the sunnier South, just in time for the Arizona Rocket Gathering.  While there, he grabbed a Polecat Aerospace 5.5" Nike Smoke kit for a Winter project and this is its story.

Introduction
My wife and I headed South at the end of February to visit my daughter — Montana was cold and Phoenix looked very inviting. I planned this vacation so that I could attend ARG 4 while we were there.

Photo sequence showing the fin slot fit.

Andy Woerner of Polecat Aerospace was one of the vendors at ARG and I have been interested in his kits for a few years now. I asked Andy about them and he showed me the components of one of them. Based on what I saw, I decided to buy one — I like the Nike Smoke.

I looked at the 4 inch and the 5.5 inch kits and decided that for the difference in money, I would prefer to have the 5.5 inch rocket. He has two models: for $200 you can get a single deployment rocket, or for $30 more ($230 total), you get a kit that has most of the parts necessary (except electronics and parachutes) to build a dual deployment rocket.  I opted for the latter.

Parts
The kit comes in a single long box. Everything is neatly packaged. The list of materials includes:

1. One fiberglass nosecone.
2. One four inch bulkhead that fits deep in the nosecone. This bulkhead is pre-drilled for a u-bolt that will be used to connect a shock cord to the nosecone.
3. Two pieces of pre-glassed airframe body tube. One is 36 inches long and slotted for the fins. The other is 10 inches long and intended to be used for the avionics bay and main chute compartment.
4. One cardboard coupler for use in the avionics bay. I'll talk more about this later.
5. One cardboard 54mm motor mount tube (MMT). This rocket is also available with larger motor mounts, but realistically I can afford to fly many more 54mm motors than 75mm or 98mm motors.
6. Four plywood fins. The fin edges are beveled, but not tapered to the center like the classic Nike Smoke fin. That did not deter me, but the purists out there will probably prefer something different.
7. Three centering rings. One is pre-drilled for the u-bolt that will be used to attach the shock cord. All three are identical in diameter and cut to accept the motor mount tube.
8. Two plywood bulkheads for use in the avionics bay. One has a step rabbeted in the edge. This one becomes the aft end of the avionics bay and is removed in order to access the gizmos you load into your avionics bay.
9. Two plywood strips that are pre-drilled and a plywood rectangle (7 inches long by 5 inches wide). These parts form the avionics sled and mounts mounts that slide over two pieces of threaded rod.
10. A sealed bag of miscellaneous hardware parts, such as the threaded rods, u-bolts, nuts, and washers. I appreciated the fact that this bag was heavy plastic and heat sealed to prevent the loss of parts.
11. Two sets of instructions: one for the Nike Smoke and one for the "Dual Deployment Bay." Each set of instructions had a list of parts that should have been included.

Dual deployment electronics bay.

Four items that were listed in the parts lists were unfortunately not included with the rocket kit. They were the two tubular nylon shock cords and the two rail guides. The screws and standoff nuts for the rail guides were included. I don't consider these missing parts to be a major problem. Over the years I have built up supplies of both. When I get around to it I will send an email to Andy mentioning these shortages.

Assembly Notes
The instructions are simple to follow and the kit assembles very quickly. First I went through the instructions and dry fit everything to see how it would work. I noticed the two slides for the avionics sled had slightly offset holes (the holes on both slides were offset the same amount) so I made sure to line them up the same.

In less than 20 minutes I assembled and epoxied the "Dual Deployment Bay." Then I started on the rocket body.

Motor mount end of the kit.

I began by test fitting the centering rings, motor mount tube, and fins. I was very pleasantly surprised by how well the fins fit into the fin slots in the body tube. I honestly have never had fin slots fit so precisely to fin tabs before. The slots were square and straight. When I removed the fins from the fin slots I realized why. The fin slots were (like the fins) laser cut. This sequence of photos at the above right shows the tight fit.

The instructions say to assemble all three centering rings to the motor mount tube (MMT) before gluing the assembly into the body tube and then epoxying the fins in place. Having the aft centering ring epoxied in place would prevent applying internal fillets to the fins. So, you may want to dry fit the aft centering ring until you epoxy the fins to the outside of the body tube and then remove the aft centering ring and applying fillets where the fin tabs pass through the body tube and where they meet the MMT. That's what I did.

Forward recovery mounting point.

Put some tape on the aft centering ring so you can pull it out of the body tube after the middle centering ring epoxy and external fin epoxy has cured. Then epoxy the fin tabs to the MMT. Once that has cured apply a heavy band of thickened epoxy just below the fin tabs on the inside of the body tube and on the bottom of the fin tabs and slide the aft centering ring in place.

The forward centering ring fits up at the very front end of the MMT, deep inside the body tube. I have no problem with that although I prefer the coupler at the top of the body tube in the "zipperless" fashion. The middle centering ring sits on the top of the fin tabs. That is fine also. However, the fin tabs are 5-5/8ths inch wide and the directions call for the middle and aft centering ring to be epoxied to the MMT about 9 inches apart from each other. That means that the aft centering ring, which is flush with the aft end of the body tube, would not seat against the bottom of the fin tabs.

Minimal seam on the pre-glassed tube.

This is probably a philosophical difference, but I prefer that the thrust of the motor not be supported solely by the epoxy joints on the MMT and centering ring. I want the thrust to be coupled from the end of the motor mount directly to the aft centering ring, then to the base of the fin tabs. The fin tabs then couple the force to the airframe.

With that in mind I had a few options: I could just build it stock and count on the cardboard to handle the thrust of a K. I could slide the MMT farther up into the body tube and then slide the aft centering ring further up so it rests against the bottom of the fin tabs. That will leave the motor firing about three inches up inside the body tube, so I might want to shorten the aft end of the body tube a little also.

Instead, I slid one centering ring up against the bottom of the fin tabs and epoxied it in place. I will apply an epoxy fillet to the centering ring this week.  I will put in a short piece of four inch phenolic tubing and add a four inch centering ring flush with the end of the body tube and rocket. That will reinforce the motor tube and also allow me to use the Nike Smoke as the sustainer in a two stage rocket someday.

Nosecone seam passes light through.

The only assembly that needed to be done on the nosecone was to epoxy in a four inch centering ring which holds a u-bolt. One of the shock cords gets connected to this. I plan also to paint the inside of the nosecone with some Aeropoxy to help seal the exposed glass fibers, which I will discuss in the Materials, Fit, and Finish section which follows.

Materials, Fit, and Finish
The fiberglassed body tube was very well done. The seam on the outside of the fiberglass is visible, but not at all bothersome. Andy recommended lightly sanding it, but I am of the school that believes in building up rather than sanding off. The fine weave of the cloth will make it very easy to fill and sand before painting. In fact this may be the perfect kit to try out some of that urethane spray filler/primer I bought from the car place.

Assembled Nike Smoke kit.

The centering rings, fins, and bulkplate were all extremely well cut, fitting very precisely. I have never seen parts that fit so well, with no gaps or tight spots that need sanding to make fit. The wood parts are all high quality Baltic birch plywood with no patches or knots in the veneer.

The nosecone is a nice looking fiberglass component that appears to have been laid up in a two piece mold. The seam where the two halves come together bulges slightly on one side.

Looking toward a bright light from inside the nosecone, one can see where the seam passes more light. The photo below demonstrates that. The material seems heavy enough, but coarse on the inside. After working in the inside of the nose cone to epoxy in the bulk plate my arms were very itchy from contact with the rough glass fibers that are exposed. However, for the price of the kit this is a huge nosecone, standing 32-1/2 inches from the bottom of the shoulder to the tip of the nosecone. It is not coated with a glossy gel coat, but rather with a matte finish which actually will make it easier to prime and paint.

The cardboard used for the dual deployment bay coupler is a decent grade of cardboard. It could be slightly heavier, but it will be adequate. After a trial flight I might want to glass the inside of the bay, but I will try it stock at first.

Synopsis
This rocket is a nicely made kit that assembles easily. The fit and finish of the fins, fin slots and centering rings made it fun to build. The things that bothered me were very slight and easily remedied so I would happily buy another kit from Polecat Aerospace. Our first launch here in Montana is in April and I'm eager to fly this rocket.

For Steve's contribution of this article, he will receive a free one year subscription to LAUNCH Magazine. This sponsorship is made possible by our friends at MM Publishing, Inc., the producers of LAUNCH Magazine. Want your own free subscription? Read the program details page for complete information.

Reader comments:

#1

I've had very positive experiences with all of Andy's kits... the only changes I made to my 5.5" Nike were a 76mm mount and adding a layer of Carbon-Kevlar to the inside of the avionics bay coupler for strength. I flew it on three L motors and an M1297 for my L3 cert before destroying it on its fifth flight due to a motor CATO. Even after falling from burnout at 3000 feet, the avionics bay and nose cone section survived, and only two fins broke on landing. It's a tough kit. I'm planning to rebuild it over the summer, with a 98mm mount instead...

daveyfire on 03-30-2007 09:26 PM

#2

I have the 5.5 Hawk and I put a loc coupler stiffener in the electronics bay, fits very well and is still pretty light.

sandmantoy on 04-02-2007 01:51 PM

#3

That's a great tip.
Thanks,

Steve_Shannon on 04-02-2007 09:51 PM

#4 It flies great!

Well, I never did get around to reinforcing the avionics bay, but it does not seem to need it. I have flown it twice now and it flies great on a J or a K. It went to 4943 on a K550, and flew straight while doing so. On both flights the shear pins sheared at apogee so I need to either use larger pins (3/32 inch round styrene right now, but may become nylon 4/40 screws soon). I painted it traditionally, with one yellow and three flourescent red fins.

Steve_Shannon on 07-03-2007 05:41 PM

#5

What? No pictures?

ddmobley on 07-03-2007 07:25 PM

#6

I don't carry a camera, but there are some pictures that others took that show the Nike Smoke as a tiny dot in a blue sky. Have a happy Independence Day! I'll see what I can rustle up.
Steve

Steve_Shannon on 07-03-2007 07:31 PM

#7

Nah, I was just giving you a hard time. Have a happy and safe 4th.

God Bless America!

ddmobley on 07-03-2007 09:59 PM

#8 Re: First look: Polecat Aerospace’s 5.5" Nike Smoke kit

I flew it again yesterday on a Loki Research K-350 moon burner. It went to 7,738 feet. Here is a picture, which Gretchen Bingman sent to me today:

Steve_Shannon on 05-18-2008 06:51 PM

#9 Re: First look: Polecat Aerospace’s 5.5" Nike Smoke kit

Here's my buddy Matt Guschausky's 5.5" Nike on an I300 for a successful L1 cert flight, taken by Rocio Crabb:



Same bird, same day on a K695 for a successful L2 flight, also taken by Rocio Crabb:



Same bird again, on a TDK K600, taken by Matt Minjarez:



The rocket is built completely stock and flies great!

SpartaChris on 05-18-2008 11:10 PM

#10 Re: First look: Polecat Aerospace’s 5.5" Nike Smoke kit

Quote:

Same bird, same day on a K695 for a successful L2 flight...

Do you happen to know how high the K695 flight was? Also was it dual deployment or single deploy?

UncleVanya on 05-18-2008 11:24 PM

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