Cosmodrome Nike Apache

The Nike body tube was placed on the template and the lines for the 4 fins and the lug were transferred. An angle was then used to lengthen the lines with the lug line running the length of the tube.

Each of the fin lines was marked a specified distance from the back of the tube; I think it was an inch but I do not remember. The fins were numbered in pencil with the characters for one through four since I was not certain that they were strictly interchangeable in terms of the sanded profiles. The fin lines were also so marked. The root edges of the fins were then aligned with their respective fin lines having their rear edges along the previously mentioned marks and were then held in place as a pencil was used to draw their outlines. A razor knife was then used to cut out the marked lines and allow the fins to slide in.

The next step was to wrap the rear of the body tube with Saran Wrap. This is to protect it from the moisture that is soon to come. When the wrap was in place, I retrieved the provided piece of cardstock and spritzed with water from a spay bottle I swiped from SHE WHO MUST BE OBEYED's laundry department. The purpose of this is to allow the cardstock to more easily conform to the body. I wrapped the stock around the body and tied it into place to dry with some surplus shroud line. The tube and wrap were then set aside to dry.

Hi John -
FYI, I am building this kit right along with you. It is my first MPR.
Thanks for documenting and sharing your build - and thanks to Mike for his comments too. This is also my first scale rocket build - I am planning to use it for my NAR/Nartrek Silver scale requirement. My fins are shaped, this weekend I will be working on the body wrap and fin slots.
-Kerry

KerryQuinn said:

Hi John -
FYI, I am building this kit right along with you. It is my first MPR.
Thanks for documenting and sharing your build - and thanks to Mike for his comments too. This is also my first scale rocket build - I am planning to use it for my NAR/Nartrek Silver scale requirement. My fins are shaped, this weekend I will be working on the body wrap and fin slots.
-Kerry

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I wish you the very best on your build, your flight and your NARTrek goal. It is my fervent hope that I do not lead you astray somehow.

I hope to get a significant amount done this weekend too.

A day later, I removed the string holding the wrap in place and, sure enough, it had been re-molded into approximately the curvature of the Nike body tube. I did a little trimming with a razor knife to remove a tiny bit of material from one end to make a tight closure and then used some sandpaper to fair up the edge.

Some slow cure epoxy (30 minute) was mixed because I perceive it to be a thinner fluid and was then brushed onto the inside of the wrap. The wrap was slid into place flush with the aft end of the BT and with the seam along the launch lug line. Some masking tape was used to hold it in place as it dried.

I worked on some other things and about an hour later removed the tape. The next task was to duplicate the fin slots from the BT on the wrap. After several trial and error attempts, I decided that the easiest thing to do was to make a slit down the center and then shave away from the outside while peering down the interior of the tube. I kept whittling away until I test fitted each of the numbered fins successfully.

A long swab was used to make a ring of epoxy around the interior of the BT just forward of the fin slots and the motor mount was shoved part way in. When the forward ring was in, I paused and swabbed another ring of epoxy around the after end. The mount was then pushed into place with the retaining bolt aligned with the seam on the lower wrap and the rear centering ring flush with the end of the tube. The tube was set upright for a while so the epoxy would flow back towards the rings as it set. After 10 minutes, I mixed some more epoxy and brushed it around the seam on the after ring and set it aside to set up.

As the epoxy on the motor mount set up, I skipped ahead a few steps and pulled out the Apache fins. These again were made of plywood and again needed to have a profile added. I marked off an 1/8 inch on each leading edge, drew a line and then marked the line with a strip of masking tape.

Since I had developed a little confidence with the best sander on the last of the Nike fins, I decided to use it for the Apache fins as well. I took it slow and, while the bevels are not perfect, they are good by my own admittedly marginal standards.

The first of the Nike fins to be installed was number 4. I test fitted it once again and then applied some epoxy to the root edge. The fin was slipped into its slot and pressed into place checking for straightness. A bit of epoxy was the filleted along each side of the BT with my finger and allowed to set up.

Fin number 3 was installed just as number 4 was except the slot was a bit looser and I needed some tape to hold things in place as the epoxy cured. Further fin installation was interrupted by work concerns and I set things aside to dry for the night.

John -
What do you think is the purpose of the hardwood dowl that gets glued into the front end of the transition section? just added strength? I'm trying to decide how far in to push it when I glue it - I guess I'll push it in all the way - then about 1/4" would stick out to the front.....

Also - are you planning to give the nose cone any special finishing for added strength? On EMRR I read about guys adding a single glass ply because the tip of the cone was easily breaking off. I'd rather opt for something more simple - maybe a good soaking of CA or sanding sealer ?
-Kerry

KerryQuinn said:

John -
What do you think is the purpose of the hardwood dowl that gets glued into the front end of the transition section? just added strength? I'm trying to decide how far in to push it when I glue it - I guess I'll push it in all the way - then about 1/4" would stick out to the front.....

Also - are you planning to give the nose cone any special finishing for added strength? On EMRR I read about guys adding a single glass ply because the tip of the cone was easily breaking off. I'd rather opt for something more simple - maybe a good soaking of CA or sanding sealer ?
-Kerry

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I know what you are talking about because I've seen that that's the next step coming up after gluing on the fins but I have not thoroughly read that section so I really don't know.

As to the NC, I don't know how to glass and will most likely douse the thin in CA.

I hope to get some more done a little later tonight.

KerryQuinn said:

John -
What do you think is the purpose of the hardwood dowl that gets glued into the front end of the transition section? just added strength? I'm trying to decide how far in to push it when I glue it - I guess I'll push it in all the way - then about 1/4" would stick out to the front.....

Also - are you planning to give the nose cone any special finishing for added strength? On EMRR I read about guys adding a single glass ply because the tip of the cone was easily breaking off. I'd rather opt for something more simple - maybe a good soaking of CA or sanding sealer ?
-Kerry

Click to expand...

Exactly. I wasn't sure if this would be a point of failure so I added the dowel. May not even need it. Insert the dowel as far as it will go, usually some of it sticks out.

I haven't tried it with this NC but wood hardener seems to protect quit well. Or, soaking the tip in finishing epoxy should work.

When I got back to the Nike Apache, the third and fourth fins were installed like the first two without any problems.

One of the things that I liked about this kit was the way the eye screw is mounted to the transition. A natural worry with any rocket, especially a heavier one, is the screw stripping out at ejection, even when reinforced by epoxy. This kit goes a long way in lessening that worry with its approach. The eye screw was screwed into a plastic anchor screw with large, aggressive threads and then backed out. A drop of epoxy was put into the hole of the anchor and the eye screw re-inserted.

The process was then repeated and the anchor was screwed into the balsa transition, backed out, the hole filled with epoxy, and re-inserted. Epoxy was used to fill around the screw as well.

On the opposite end of the transition, a piece of wooden dowel was epoxied into the cavity to strengthen a potential failure point.

The base of the Apache portion of the rocket is a built up affair and I have to admit that I almost ruined it. The kit came with a short length of 29mm motor tube which serves as the base and what amounts to a 29mm thrust ring. There was also a coupler tube to fit withing the motor tube. The first thing I was instructed to do was to mark the longer of the two interior tubes at 1/4' and then epoxy it into one end of the motor tube leaving 1/4" hanging out. This was easily done but the coupler would not fit into the motor tube so I had to sand it down some, removing my marks. It was easily marked again and then I decided to use white glue instead of epoxy. It was tight and I did not thing it was a realistic failure point.

The next step was simple enough. The thrust ring was glued in place at the opposite end of the motor tube. Again, white glue was used.

The interior joints at both ends were then filleted with white glue and it was set aside to dry for a short while.

I took a look at the Apache nose cone while the base assembly was setting up. It was reasonably clear balsa with just a touch of roughness on one side. I decided to harden it some by dousing it with some thin CA.

This next part is where things became dicey because I misunderstood the instructions. The instructions were correct but I was letting a single word cause me to misinterpret them and even ignore (subconsciously) other verbiage that should have set me straight. I was supposed to sand a bevel into the portion of the coupler tube that extended from the motor mount. It was supposed to transition from its natural diameter to the diameter of the main Apache tube. Essentially, it was to taper to 0". That part I got and most of the tapering was done with a sanding stick. It was the next instruction that got me. I interpreted it to mean that the Apache tube would be butted up against the freshly tapered coupler and epoxied into place with a simple butt joint resting upon a "surface" that had just been sanded from a surface into an edge. I just KNEW it was going to be the primary failure mode of each and every flight, if the rocket even made it to the field without breaking at that point. I was already considering rolling my own coupler to fit into both the original coupler tube and the body tube so that I would have more gluing surface and something to try and hold things straight. As stupid as this sounds, I was convinced that was what I was supposed to do. Thankfully, an uncommon bout of sense had me read the instructions again and the word that had thrown me was thrown up in relief. THE AFT END OF THE APACHE TUBE WAS TO BE BUTTED EVEN WITH THE AFT END OF THE BASE. "Butt" had mislead me into ignoring the stupidity I was displaying. The Apache tube fit THROUGH the sanded coupler, through the motor mount and through the thrust ring. It should have plenty of support. I again used white glue instead of epoxy.

With the Apache tube secured in the Apache base, I moved the base over to the fin marking guide for the Apache and transferred the marks. Doing it with the smaller tube made me wish again for the wrap around type but the job got done.

An Estes angle was used to run the 4 lines the length of the base and one of the lines was run the length of the entire Apache tube. Each of the lines was marked off 1/4" from the aft end and then the fins and lines were numbered in the same manner as the Nike fins and slots were cut.

Mounting of the Apache fins was, for some reason, more difficult than the mounting of the Nike fins. This is not to say that it was really hard; they just did not go as easily. The first fin was re-checked to make sure it fit and then epoxy was placed in the slot and along the root edge. The fin was then pressed into place and held with tape.

I'll get the rest of what I have done later. Hopefully I'll be able to upload photos without getting timeouts and reset errors.

The second fin also went on without any problem.