Continuing with my self-imposed project of going back to the roots of the hobby, I scratch built the Astron Mark K-2. The plans for this are available from JimZ's site.

It's also based on the BT-30 sized tube and nose cones. It uses 1/16" fins. I swapped out the 1/4" thrust ring for a couple of cardstock thrust rings that I made with my laser cutter. I also fashioned a BT-30 3-fin alignment guide. The tube and nose are from Balsa Machining.

Attached Thumbnails

 

I started by marking where the fins will go, and how far up the body they should be placed. I never trust my eyes for something like that.

Then, using the fin alignment guide, the fins went in place. I tacked them with Aleen's Tacky Glue.

After the set, I added three thin layers of fillets, using Elmer's Glue All. That made almost all of the bubbles disappear from the fillets. The launch lug was also glued on at that time. I think it was a launch lug that I hand rolled.

Attached Thumbnails

       

The two thrust rings were inserted into the back end of the rocket, set so that the engine would be flush with the bottom of the rocket when inserted. I would have expected the engine to stick out a bit so that one could grip it with pliers. But, maybe that hadn't been figured out by the time they produced kit # 2.

Oh, I just double-checked my claim. The older instructions say to insert the engine block 2 3/4" into the tube. That's where I mounted my thrust rings. But, the later instructions say to leave the engine overhanging by 1/4", like I would have expected. Maybe someone did learn between the two versions. As I mentioned in the Scout thread, doing rocketry back then was the same as experimenting with rocketry.

Also, still to be figured out, was how one should attach the shock cord. At least it was understood that a shock cord was needed! This rocket is from the times when two slits were made in the body tube, and the shock cord was weaved through the slits, and glued in place. No knots needed at all, apparently. (Oh, I just double-checked my claim. No knots mentioned in the older instructions. A knot was mentioned in the newer instructions. Launch and learn, I guess.)

Attached Thumbnails

 

I didn't show all of the finishing work. But, I covered it with sandable auto primer three times, sanding smooth between each coat. The final paint job was a light coat of white, followed by two thicker coats.

No pictures, so imagine: To avoid drips, I paint the rocket on the end of a 1/2" dowel. Instead of just setting the rocket down to dry, I slowly rotate the rocket over the next 4 to 5 minutes. This way, any slumping the paint might want to do will get averaged out because "down" keeps changing.

I printed the decals on clear decal stock. I based the design on the image in the 1961 catalog. I was a bit unhappy with the long stripe. I should have cut it out with more clear decal material on the side. As it is, the decal could flex a bit, and I didn't get it quite as straight as I had hoped.

Edit: I just noticed that this is the only rocket illustrated with decals in the original catalog.

Attached Thumbnails

   

When one is good, three is gooder.

So, having built a BT-30 Mark, I went ahead and built a BT-20 Mark. Same fin pattern, same tube length. The nose is one that I made on my lathe, made a silicone mold, and then cast in polyurethane resin. Because why not. If one step is good, then several must be better, right?

And as a finale on the Mark, I scaled it down to a BT5 tube. It's scaled from a BT-30 size to a BT-5 size. It's small enough that I didn't include a parachute or streamer. I'll let the shock cord with a heavy nose cone as a streamer. There's a name for that kind of recovery.

Attached Thumbnails

 

I went really old school with my Mark. I made a balsa thrust ring and mounted the engine flush. This means poking the motor out with a dowel.

I painted it with red and black dope. Flew like crazy; really zoomy. I ended up mostly flying it on 1/2A6-2 and 1/2A3-4T.

I donated it to the Sunriver Science Center mini-museum.

__________________
NAR #27085 - Oregon Rocketry - SAM

That's the way to do it!
I spray horizontally (engine casing and dowel in the engine mount)
After spraying I walk around the back patio turning the dowel and rocket so no drips can form.
It usually takes a minute or two until the paint "skins" over - no drips!

I'm enjoying your "K" kit builds!

__________________
Hans "Chris" Michielssen
Old/New NAR # 19086 SR

www.oddlrockets.com
www.modelrocketbuilding.blogspot.com
http://www.nar.org/educational-reso...ing-techniques/
Your results may vary
"Nose cones roll, be careful with that."
Every spaceman needs a ray gun.
Look out - I'm the Meister Shyster!

Nice builds ! I believe the old term for recovery without a chute or streamer was simply "Break-apart".

Yep, that or "Nose-Blow".

__________________
Hans "Chris" Michielssen
Old/New NAR # 19086 SR

www.oddlrockets.com
www.modelrocketbuilding.blogspot.com
http://www.nar.org/educational-reso...ing-techniques/
Your results may vary
"Nose cones roll, be careful with that."
Every spaceman needs a ray gun.
Look out - I'm the Meister Shyster!