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Estes MIRV-- Sort of a build thread

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BABAR

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Already built, but figured I'd show how I did it. Haven't flown it yet. I think I have some ideas from the build that others may find useful
Here are finished pics, except that I haven't tried to Pledge Future on it yet.
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BABAR

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Biggest thing on reading reviews of this is paint, particularly for the foam sections.
Two problems:
first is that the foam dissolves if you don't use special paint. They tell you what primer to use, in the instructions it says Testor's Model Master 2937 grey or 2948 white.
second is that foam is, well, foam, it has a bunch of dings in it, it doesn't look like it would hold up well, it is not very smooth, you can't sand it. I mean, it's FOAM!

I don't have the patience to develop the skills of Der MicroMeister and Hornet Driver and a bunch of other Craftsman on this forum, but I did want this to look good, since it was a kit.
Anyway, I tried my Mylar tape for the foam black sections, and I think it came out well. Have to see how it does with the weight come flight time.

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The first pic shows the bottom foam section after I taped it (forgot to get a PRE pic here.) Next pic shows the two of the THREE sustainer sections (for those not familiar with this rocket, it has a single engine booster sections with a plastic duct system that routes the ejection GASES to three separate sustainers. The stick in the middle is sort of like a launch rod/guide for the sustainers to keep them aligned on boost.) anyway, second pic shows one of the foam pieces naked and another one taped.

Later pic shows the Sharpie marker which is used to touch up any areas I missed with the tape.

Using tape (basically similar I guess to trim Monocote), the DISadvantage is that if you are also going to do any painting, you have to do it to each part before you attach it. Pic 6 shows how I painted the rear ends of the body tubes of the sustainers before attaching them.
 

BABAR

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IMG_5142.jpgIMG_5143.jpgIMG_5144.jpgIMG_5145.jpg

I did elect to paint the fins. Kind of a silly thing, each fin in this kit (both the 3 booster fins and the 9 [3 each] sustainer fins) comes in two parts that have to be glued together. The grain direction is identical on both pieces, so I don't see the point, maybe somebody else can clue me in as to why?

Since I had to paint the fins pre attachment, I masked off the attachment areas so I wouldn't have problems gluing paint to paint. Again I then used the black sharpie to cover any areas that might be exposed. Due to the design of the model, most of the areas I left blank are not exposed.

One really NICE thing about this kit, the premade foam parts make fin alignment a snap, essentially you would have to work to misalign the fins. I will give Estes a big plus on that.
 

BABAR

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As mentioned, the central dowel on the booster runs up the middle between the three sustainers. Each sustainer has a central launch lug that mounts on this 3/8" dowel/rod. The supplied dowel only goes about midway up the sustainer length. I figgered the longer the rod and more distal/forward the lugs, the better the alignment would be so I bought another 3/8" dowel and measured it to go the length of the sustainer body. Each of the three lugs goes a different length, so that they can all be mounted in sequence.

The first tendency is to think of this as a launch rod, meaning you want the sustainers to stay on it as long as possible for stability. Then when you think about it, you realize this bird is already up and moving when the sustainers light, so there is no "ramping up" of speed like on launch, so actually the SHORTER the time they stay on this dowel the better. So I have them as far forward as I can get them. One nice thing, the decals come with little labels, 2 As, 2 Bs, 2 Cs, so once you figure out the order (you have an external lug for launch on ONE of the sustainers that has to match a lug on the booster) you can label the sustainers to know which one to put on first and which one last (I put C on the one with the lug.)

Given Alignment is critical, I used 3/8'" dowels inside the lugs when I glued them on to make sure I had the longitudinal alignment correct, you can see that in pic 2.
 

BABAR

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Here are the pics before putting the decals on.

On problem with the tape rather than paint is that you have to put the launch lug on AFTER you put the tape on. But you can't attach the launch lug to the tape.

I solved this by marking the area for the lug after taping, using EXACTO knife to carefully cut a rectangle away where the launch lug would go.
I used a SharpieIMG_5191.jpgIMG_5192.jpgIMG_5193.jpgIMG_5194.jpg to black out the area of foam. I don't THINK a sharpie causes any problems with adhesion (guess I will find out) the way paint does. After blackening the section with the Sharpie, I also blackened the launch lug segment (again, I don't THINK this will cause adhesion problems).
 

BABAR

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The booster has it's own lug, and there is a standoff so that lug position on the booster will match the lug on the one sustainer that has a lug. BTW, I papered all the fins using adhesive backed white paper before painting, and did the same for the standoff section. Masked the edges of fins and standoff that would need glue (for the red center fins and for the booster fins, the root edges are completely covered by the foam sections, to no problems there. For the outer sustainer fins, most of the fin that needs "adhesing" is also obscured, so works really well for this model. For the STANDOFF section, given it was small, I didn't paint it, just "Sharpied" the whole thing. Had to be CAREFUL to keep track of the root edge, however, simply to make sure I kept the grain direction correct.


Even the standoff has its own foam "slot" so alignment is likewise easy. BUT the alignment of the two lugs (booster/sustainer) has to be perfect. So once I had the standoff glued in, I put the pieces of the rocket together, marked the location on the SUSTAINER section where the lug was going to go. I think ran a section of launch rod down line (no lug yet on the sustainer) from this to the standoff, rubber banded it in place, and used this to make sure the alignment of the BOOSTER lug would be spot on.

Once I glued this is place (with a bunch of fillets, it is kind of a puny standoff and lug), I did the operation in reverse. I put the launch rod segment in the now fixed booster lug, ran it up to the spot on the sustainer, and used it as a guide to glue the sustainer lug in place.

I wasn't too happy about gluing a lug to foam, I think given all the other things they did with foam would have been better to cut a slot in the foam to make for perfect alignment AND to put a piece of wood in there which I think would be stronger than lug to foam. But we will see.

I did put some touch up tape over the rectangular hole in the original tape after gluing in the lug, and again used the Sharpie to touch things up.
 

BABAR

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Decals (something I rarely see as I usually do scratch building, and in fact often don't even paint!)

Very mixed reviews to Estes on this.

First, the decals themselves where nice, they didn't tear at all, the complemented the model well.

Second, come on Estes, give us enough decals to do all three sustainers. Meaning THREE "MIRV" decals, not two. Meaning SIX red circles, one for each of the sustainer lateral fins, not four.

Also, somebody in quality control messed up. Those rectangular boxes the go just above the sustainer fins? All you had to do Estes was make sure the center box was CLEAR, not WHITE. Look at pic 3, the right side has the original ESTES provided decal, with a WHITE center. The one of the left is piece of Mylar tape I put over the center. Unfortunately I didn't learn that the enemy of good is better. My first tape piece was just a bit off, when I tried to reposition it :facepalm: it ripped up the decal. Fixed with scotch tape (yeah, DEFINITELY not a MicroMeister or Hornet Driver job!)

BTW, to cut the mylar tape to fit, I put the tape on waxed paper, cut to fit, left a tab on the waxed paper. Pulled of the waxed paper, and voila, instant solid color decal.
 

BABAR

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As I said, we will see how the flight report goes, maybe with my club MidSouth Rocket Society
https://www.midsouthrockets.com/
this weekend.

I am still a bit anxious about how well this gets off the pad with a C6-0. Note to Estes, for rockets like this and Venus Probe and Exoskell, put in a larger engine mount.

Were I to build this again, I would probably use Trim Monocote rather than tape (simply because had to overlap the tape a bit to cover the body tubes), and I would probably have Monocote'd the fins as well.

Comments appreciated.

Tom
 

BABAR

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couple of other things

I am at 130 grams WITHOUT engines or wadding.

I put a small hot pink streamer in each sustainer, mainly to make each easier to find.

I skipped the trifold shock cord mount. I am using Kevlar thread for attachments. I poked a needle hole mid body tube for each sustainer, wrapped a loop of Kevlar around the outside (it is all hidden by the foam, and I put these in BEFORE gluing the tubes to the foam), Kevlar runs out the front and is attached to the estes Elastic and the nose cones.
 
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