XXtreme Blue

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So here is my next project, I actually started this about four years ago. I guess now is as good as any time to finish it, I'll try to have it ready by URRF 3
 'XXtreme Blue'
 There is all 6" blue tube for the airframe. Starting on the left is the fin can/motor mount. It has 1/2 plywood delta fins mounted thru the wall to a 4" motor mount with an Areo Pac motor retention already assembled. At the top of it you see the BluT coupler, inside it is a section of sliced BluT to make the coupler a double wall construction. The short section to the right is the drogue bay with the altimeter bay in the top of it, the Alt bay will also be Dbl wall const. To the right of that is the Main chute bay along with a pile of cut bulk heads cut out of 3/4" birch plywood. Then to the right again is the conical nose cone,
 the whole rocket will be +/- 12' tall.
 I'll add more detailed photos to our URRG forum as soon as I get started on the project.

FYI; the big tubes, FG nosecone and FG fins you see behind this are a Nike Smoke project that will be a future build sometime in the future. (This is another project I have been collecting parts for since LDRS 31)

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Since I wanted a doubled up bulkhead on this the first thing I needed to do was go down to the local rocketry supply center known as Home Depot to get a 'U' bolt that had enough threads to extend out both sides of the bulkhead.

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Here are all the parts of the fin can/motor mount coupler assembly.

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I first mixed some 15 minute epoxy and added some micro balloons to thicken it so it would stay where I wanted to. This is the interior of the coupler with the bulkhead epoxied into place.

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This is the exterior of the coupler with the bulkhead in place. The bulkhead is recessed for a reason that will be explained later.

[RKeller]

Lookin good Dutch, what's the reason for the double bulkhead?

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Lookin good Dutch, what's the reason for the double bulkhead?

Even though it amounts to over kill I figure that with the total weight of the fin can/motor mount section and the added weight of a 6 Grain 98 mm motor case that there will be no way that the bulk head will fail or the 'U' bolt be able to pull through it when the apogee charge separates the rocket or the main charge brings out the big chute and "jerks" the harness connection point and bulk head.

Besides another Rocketeer once told me that it's best to build your rocket like a "Brick Shit House" because 1. You can always put a big enough motor in it to get it off the pad. and 2. It will survive events that you wouldn't expect it to.

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OK, so now the coupler is epoxied into place.

Here you'll also see the altimeter and drogue bays ready for the next step in the build.

What you can't see too well is that on both the interior and exterior of the coupler I poured in enough epoxy to embed the 'U' bolt nuts so they will never come loose.

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One last thing I should point out is the pressure relief hole I drilled into the top of the coupler bulk head which will make sliding the 98 mm motor in and out of the fin can sssoooooo much easier.

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Here you see the Aeropac motor retainer (sans the screw cap) done so to better view the aft end. Although I did use the screw inserts that come with the retainer you can see that I like to embed the screws in epoxy as well. You can also see that I took two short sections of coupler, cut one to slide into the other, and then epoxied them into the bottom of the fin can to make the end of the tube less susceptible to damage due to hard landings.

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Since the whole air frame is blue tube I won't be fiber glassing it, but I do need to fill the spirals before painting it.
The other day I picked up a tube of glazing putty and here you see that I've done the Altimeter Bay and I'm working on the Drogue Bay.
The glazing is easy to use, it dries very fast, and you can easily sand off the excess.

I still have the Main Bay and the Fin Can to do, I also have some saw kerf marks to fill on the fins, but for that I'll use Bondo as they are a bit deeper than the spirals are.

[RKeller]

I'm a big fan of bondo spot and glazing putty. I use it for filling mold/parting lines on plastic and fiberglass nosecones too. great stuff!

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So I started working on the Altimeter Bay
Here you see the four sections of all thread that are spaced so I can put two of my altimeters in the bay.
I have all of my altimeters mounted to the same type of sled so I can install anyone of them in any of my Alt bays.
(This includes any of my rockets from a 3" air frame up to a 7.5" airframe so far.)
You also see how the 'U' bolts are mounted here. The space between the bulk heads is approximately the distance of the inner sliced coupler which the bulk heads will sit on. There is a lot more I do with this but for now this is ready for the two couplers to be epoxied together.

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So here the Altimeter Bay is epoxied together for now. I still have to install the charge contacts and wells yet, and the key switches but I'll show that in detail as I do them.
So for what I did here I first assembled the two couplers and then bolted the bulk heads in place. Then I slid the inner coupler assembly out and prepared my epoxy using US Composites 3 to 1 mix I did a batch large enough to coat the inside of the outer coupler and then used West systems adhesive filleting blend to make part of the epoxy thicker which I spread on the Drogue side of the bay. Then I slid the inner assembly into the bay and set it aside to cure.

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Not to start a glue thread here but this is what I like to use for epoxy. I used to use all West System but found US Composite to be of the same quality at half the price. What is nice it that the West filleting blends also work with US C.
The 405 is nice because you can add as much as you like to get any consistency that you need from syrupy to a heavy thick paste.
Actually the 405 can even be used in BSI epoxy but one should note that the thicker you make your mix, the shorter the cure will be.