First scale scratch build, the Astrobee D

[qquake2k]

I've admired Aerotech's version of the Astrobee D for some time now. But after acquiring Aerojet's CD of information about it, I've decided to scratch build one. It will be half scale, 3" diameter and 76" long. Much to some of your chagrin, I'm sure, I've decided on a 29mm motor mount. That'll give me many, many choices of motors, from G's to I's (which I'll never fly it on), with altitudes from 600ft all the way to 2300ft. I'm thinking I'll keep it in the 1500ft range.

When I first looked at the photos, I thought that the fins were very simple. However, after looking closely at the drawings, I've realized that the fins are very complex indeed. There are bevels and bumps all over the place! I know my limitations. My patience and skill levels are nowhere near enough for fins like these. So the fins will be flat. I'll focus instead on some simpler scale details.

One of the details I've decided to focus on will be the original launch lugs. Initially I was planning on using Acme conformal rail guides, but I've since decided on using rail buttons on the rear of the rocket, and making scale decorative launch lugs for the front. I've decided on this for two reasons. One, scale launch lugs won't fit in a standard rail. And two, as far as I can tell the launch lugs were positioned on the front of the rocket, where the logos will be. I don't want them facing the rail.

[qquake2k]

Another scale detail I've decided to tackle are the antennae. I've found photos of two different configurations, but only a drawing for one of them. That's fine, I prefer the second one anyway. The Aerotech kit includes decorative antennae (first design) that are removed before flight. I'd like to make mine rugged enough to be able to leave them on during flight. I'm thinking about using pieces of brass that I can solder together, but haven't decided for sure yet.

I've also decided to put real screws around the top and bottom of the payload section. The original payload section was available in two lengths, one caliber (6" long) or two calibers (12" long). I've decided on the two caliber version, which in half scale will be 6" long. It will be painted only, it won't be a removable section. As for the screws, I haven't decided on a size yet. I'm thinking maybe 4-40. They were flat head, and the holes were all counter sunk. I'll have to experiment with them to see what looks good. The original screws were a weird size, .190"-24 UNC, which I've never heard of before. Half scale would be .095", which is close to a #3, but I doubt if I'd be able to find any #3 screws. I have seen 4-40 and 2-56 locally, so I'll probably choose one of those sizes.

[cjp]

This should be another outstanding build.

[bill2654]

Im subscribed!

[jungmann1]

Alright, Jim, way to up the bar, dude. Check out microfasteners.com when you get serious about picking the screws for the payload section. I, too, have been bitten by the scale bug and am, thanks to my friend Jeff in Fayetteville, starting on a TLP Nike Ajax. John.

[qquake2k]

This should be another outstanding build.

Im subscribed!

Thanks guys! I'm going to do my best. The paint should be a bear, there's a lot of detail. But since my b-in-law works at Aerojet, and he's an excellent model builder, I'm gonna make him help!

[qquake2k]

Alright, Jim, way to up the bar, dude. Check out microfasteners.com when you get serious about picking the screws for the payload section. I, too, have been bitten by the scale bug and am, thanks to my friend Jeff in Fayetteville, starting on a TLP Nike Ajax. John.

I don't know that I've caught the bug, the Astrobee D is fairly simple, as scale rockets go. There's a lot more detail on the Nike Ajax. But I think it'll be good for my first attempt. I'm excited about getting started, but that excitement might wane as I get further into it. The devil is in the details!

[qquake2k]

Aerojet used Sweetheart drinking straws to make the igniters. I don't know why, but I think that's funny!

[qquake2k]

Alright, Jim, way to up the bar, dude. Check out microfasteners.com when you get serious about picking the screws for the payload section. I, too, have been bitten by the scale bug and am, thanks to my friend Jeff in Fayetteville, starting on a TLP Nike Ajax. John.

You're right, Microfasteners.com has #3 stainless flathead machine screws. And they're not very expensive, either.

[jungmann1]

You're right, Microfasteners.com has #3 stainless flathead machine screws. And they're not very expensive, either.

Always glad to be of help, dude!~

[cjp]

Jim,I spent 11 years working a General Tire('71 to '82) in Akron,Oh. parent company of Aerojet General.We would get News Letters mailed every month informing us on what our other plants are doing and there was always something about what was going on at Aerojet.Seeing those pictures brought back some nice memories.We(AeroJet) made the large balloons that kept Apollo capsule floating upright after splashdown.

[judo]

Subscribed

[qquake2k]

Well, the components were supposed to be here yesterday, but they never showed up. That's okay, I want to take my time with this build anyway. I did get the centering rings cut out this morning. I used 1/4" birch plywood. As usual, I cut them with a 3-1/4" hole saw and sized them on my lathe. I cut the center holes with a 1-3/16" hole saw, and sanded the holes to fit the 29mm motor tube with my Dremel.

[qquake2k]

I also cut out the discs that will be the half moon baffles with a hole saw, and filled the pilot holes with epoxy.

[jeffgeraci]

I sure enjoy you're build threads, they're fascinating..... and free!!!

[qquake2k]

I marked the aft centering ring, and drilled for the 6-32 tee nuts. I pressed the tee nuts in, and covered the back sides with epoxy, being careful to keep epoxy out of the holes. In case you haven't noticed, I did initially epoxy the rail button boss to the wrong side of the aft centering ring. I had to sand it off and epoxy a new one to the other side.

[judo]

If you felt like cheating, you could show the same CR and baffle photos over and over and it wouldn't make much difference.

[qquake2k]

I call them "bosses", for lack of a better term. They're just small blocks of plywood epoxied to the centering rings that the rail buttons will screw into.

[qquake2k]

I cut and fit the bulkhead that will go into the upper body tube. I had a baffle plate from a previous build that I didn't use, so I'll use it in the Astrobee.

[qquake2k]

I sure enjoy you're build threads, they're fascinating..... and free!!!

Don't worry, I won't start charging for them!

[qquake2k]

If you felt like cheating, you could show the same CR and baffle photos over and over and it wouldn't make much difference.

You know, you're right, I certainly could. But I don't. I've thought about condensing my build threads and focusing on just the new parts of the builds. But new people join the forum all the time. Someone who hasn't read any of my build threads before may not be familiar with my methods. Almost all of the techniques I use I learned here. I'm just giving back where I can. I do know that my builds have helped and inspired several people here, and that is humbling. My builds may be getting boring to some, but not to others. As long as I know that at least one person is enjoying and/or reading my threads, I'll keep posting them.

[qquake2k]

I haven't decided what to use for the fins yet. At first, I was going to use 1/4" plywood. But the real fins tapered down to 1/8" thick in places, so I was afraid 1/4" would be too thick. Then I was planning on using 1/8" plywood, but they're pretty big. I'm afraid there might be some flutter. (Although my LOC-IV and Hyperloc 835 have 1/8" fins, and I haven't had any problem with them. And I've flown the Hyperloc on an I.) But I just don't think 1/8" fins would look right. I thought I might compromise, and use 5/32" Finnish birch plywood, like I did on Tank Girl. I drove to Woodcraft, but they only had two pieces of it, and they were both warped. I probably could have made it work, but I didn't feel like paying $21 for a piece of warped plywood.

I might have to order some 3/16" plywood from Balsa USA. They have a $25 minimum order, and with shipping it would be $35. But I'd have plenty left over for future builds. I don't know what to do.

[bill2654]

Go with the 3/16". I use it on most of mine. I didn't know Balsa USA had a minum order now. Like you said you will have plenty for future builds! You weren't thinking of slowing down any way...right?

[qquake2k]

Go with the 3/16". I use it on most of mine. I didn't know Balsa USA had a minum order now. Like you said you will have plenty for future builds! You weren't thinking of slowing down any way...right?

You get yours from Balsa USA? Is it usually pretty flat?

[daveyfire]

Aerojet used Sweetheart drinking straws to make the igniters. I don't know why, but I think that's funny!

Packed with BKNO3. Hm, I think I'll have to try this

[bill2654]

You get yours from Balsa USA? Is it usually pretty flat?

Always 1st rate!

[qquake2k]

Always 1st rate!

I think I'll order some tomorrow.

[jpummil]

Alright, Jim, way to up the bar, dude. Check out microfasteners.com when you get serious about picking the screws for the payload section. I, too, have been bitten by the scale bug and am, thanks to my friend Jeff in Fayetteville, starting on a TLP Nike Ajax. John.

Awesome tip John! I wasn't aware of microfasteners.com. Was just about to order some 4-40 x 3/16 set screws at a premium. This saved me some bucks AND gave me a new vendor for other projects on the blackboard.

Glad you liked the Ajax...I KNEW that was above my modelling skills (and patience level).

[jungmann1]

Awesome tip John! I wasn't aware of microfasteners.com. Was just about to order some 4-40 x 3/16 set screws at a premium. This saved me some bucks AND gave me a new vendor for other projects on the blackboard.

Glad you liked the Ajax...I KNEW that was above my modelling skills (and patience level).

Yeah, the Ajax is coming along. Doing quite a bit of modding as far as construction sequence but I feel pretty good about it so far.

[qquake2k]

Yeah, the Ajax is coming along. Doing quite a bit of modding as far as construction sequence but I feel pretty good about it so far.

Is there a build thread or pics of the Ajax?