Ye Olde Rocket Forum - View Single Post - Dr. Zooch Mark II build...

Moving on, we get to the fun stuff.... Now you get to see just how good you are!

Start by cutting the 'blowout panels' out of the 'upperstage' body tube. They are the four small black rectangles just under and opposite the main black bars of the roll pattern on the upperstage tube. Carefully score them several times with your hobby knife until you cut through; I cut the two long sides first and then turned the tube 90 degrees in my hand to make the two short 'end' cuts. Once you cut through, gently lift the panels free. Cut all four out.

Next, get a pair of reading glasses or a magnifier, and if you're like me drink something to give you a steady hand... LOL This is where it gets interesting! Carefully cut the yellow tank dome from the wrap sheet-- it's the yellow 'flower-looking' thing. (Yeah, at first I thought Wes's daughter had hacked into his graphics program and put flowers on the wrap sheets to dress them up too, but this thing DOES serve a very cool purpose!) Once you've liberated the tank dome from the wrap sheet, VERY VERY CAREFULLY cut through the gore lines on the dome radiating out from the center. The gores stay attached to the center of the dome, but you cut to the outer edge. Once you've accomplished this feat, and had another drink of something to steady your hand again, get your white glue and start gluing the gores back together, overlapping them behind each other as shown in the instructions. There are the tiniest glue tabs I have EVER seen on the edge of each gore. Of course I flubbed this up, and having fat, cut up, smashed up old hands, I luckily could resort to my collection of surgical hemostats to actually get the overlap right and clamp it up to dry. Be careful though, as too much glue softening the paper or taking too big a bite with the hemostat will screw it up, as you can see in a couple spots in the pics. There is definitely a learning curve here, but if you can do this and pull it off perfectly, congratulations you're now an excellent candidate for being a successful neurosurgeon! Seriously though, while stretching one's capabilities, it's certainly not impossible, and if you flub, oh well, it's inside the rocket and the only way you can see it is by looking through those itty-bitty blowout panel holes you just surgically-precise cut!

Ok, here's where I deviated from the instructions a tiny bit. I figured 'one cool deal like this deserves another'. There is a 'seal disk' in the kit, used to seal off the upper cargo section from the blowout panels and to-be-installed tank dome below. So, I fitted this seal disk to the tube (had to sand a smidge off for a smooth easy fit) and then upended it, and put centering marks on it using my steel ruler. Then I traced the antenna canister/instrument cone outline from the wrap sheet onto typing paper, and cut that out. Then, I traced around that cutout typing sheet pattern back onto an unused side of the cardstock wrap sheet, and cut that out with my hobby knife and glued it up into another paper cone. This will be the upperstage rocket motor. Titan II's used 'fire in the hole' staging-- the upperstage rocket motor ignited while the lower stage rocket motors were still burning, but about to burn out. That's what the 'blowout panels' are for: to vent the rocket motor starting up. This negates having to have ullage rockets to slosh or 'seat' the propellants against the bottom of the tanks and fill the lines like would be necessary had the first stage motors already had shutdown. (Hey, this WAS the dawn of the space/missile age after all; gotta shave some risks and complications out somewhere! ) Anyway, once you've got this new paper cone, center it and glue it up to the seal disk, NOT the weighted bulkhead The seal disk is much thinner than the bulkhead. This will represent the upperstage rocket motor visible inside the blowout panels just above the tank dome on the finished rocket.

Next, I'd recommend going over the now hopefully completed tank dome with a good smear of white glue front and back and let it dry again. It took me three steps to glue all the gores, and I popped a couple trying to 'kneed it with my thumbnail to give it a domed appearance' per the instructions, so I reglued that busted gore seam and gave it the once over front and back with a little more glue to help strengthen it up. Once that's dried, then work it a little to 'round it out' some.

Coat the screw eye thread with glue and screw it into the bottom side of the long weighted bulkhead, opposite side from the weighted filler plug. I had the screw eye bottom out on me and hit the weight, and refuse to screw in all the way, so after three tries I moved over and screwed it in at an angle to get it to screw in all the way. I used Titebond II dark glue for this for added strength. Using white glue, paste the now finished tank dome on top of the bulkhead, covering the weighted filler plug. Center it up as best you can.

Test fit it in the upper stage tube, and test fit your upper seal disk and rocket nozzle, but DON'T GLUE IT UP YET! Mark the bulkhead so you can replicate the depth. You want the tank dome visible but not even with the blowout panels.

Also, since I have a pico-altimeter I might want to fly in this rocket, I drilled a 1/4 inch hole up from the bottom of the seal disk inside the upperstage rocket nozzle for an altimeter vent. You can omit this step if you don't plan on ever flying an altimeter. Paint the seal disk bottom surface and outer rocket nozzle Testor's #1180 steel, and the inside flat black, and set it aside to dry...

More after the schoolbus route and enjoy the pics! OL JR