NEW Dr. Zooch Rockets-- the Crumman C3C...

[luke strawwalker]

Well, after some time and speculation by some folks here on the forums, I've been given the go-ahead from Wes at Dr. Zooch Rockets to do a build thread on the beta build I did for him last fall and early winter...

The rocket is called the "Crumman C3C" from some of the ant characters in some of his comic strips. It's part of his "value lineup" of low-cost kits that are still high quality and interesting, more than just the typical "3FNC" type kits in this price range, yet also within reach of rocketeers on a budget in this down economy...

It's a pretty simple kit to build, based on BT-20 tubes. It has a very "Titan III-C" appearance to it, although with external fins added for stability. The wraps are tailored for the kit with "Crumman" (aerospace company) symbols and fin numbers and stuff applied. It's a pretty quick build though it uses a novel means of attaching the motor hook.

So, lets get down to it...

The kit came in the standard 4x4x12 inch mailer box typical of Dr. Zooch kits... Inside you'll find 3 BT-20 size tubes-- (1) 8.5 inches long, (2) 6.75 inches long, 3 nosecones- 1 pre-ballasted, 2 unballasted SRB nosecones, a kit bag containing a snap swivel, a screw eye, a motor clip, a motor block ring, and a launch lug, 2 sheets of balsa fin stock, a wrap sheet with cutout wraps for the tubes, a recovery package of standard trash-bag chute, shroud lines, elastic shock cord, Kevlar cord, and a strip of sticky dots. You'll also need to get on your own standard building supplies like a hobby knife, sandpaper (I recommend 220 and 400 grits), white glue, yellow wood glue, small bottles of Testors 1181 "Aluminum" paint, copper, white or black paint, Krylon Crystal Clear acrylic spray, a good ruler, 1/2 inch masking tape or electrical tapes, emery board, a straight edge, and your brain and some building skill...

We'll dive into the build next... A note about this build thread... since the kit uses pretty straightforward building techniques, I didn't take a ton of build pics like usual. The most build pics I took were of the technique I use for "hardening" balsa nosecones and transitions and such with CA, since that has been a pretty frequent topic of discussion fairly lately here on the forum, and I try to use my build threads to illustrate these sort of techniques photographically and in print for those unfamiliar with the process... I didn't bother photographing stuff like assembling the parachute or gluing wraps on the tube, since those things are well illustrated in the Zooch instructions, and pretty straightforward anyway. I did photograph the more novel steps in building the kit, which folks might not be used to, and a few more generalized pics along the way of the build just to make it interesting.

More to come! OL JR

 

[luke strawwalker]

The kit starts off with the wraps... first mark vertical lines down the tube with the old doorjamb method, or better yet, an angle or tube guide. These lines align your wraps when you apply them to the tubes. Next cut the wraps out with the SHARP hobby knife and a ruler. I like to "precurl" mine a little bit before I start, especially when wrapping them around these smaller tubes like the BT-20. Apply a THIN layer of WHITE glue around the EDGES of the wrap sheets (be sure you get the right wraps on the right tubes-- the main rocket core and the SRB's are different lengths, as are the wraps) and then CAREFULLY align the edge of the wrap with the vertical line... stick the wrap down tight, and gently roll the tube onto the wrap, keeping it straight and edges of the wrap aligned with the edges of the tube. Burnish down the seams and ends of the wraps to the tube with a rounded Sharpie marker or equivalent. This will make nice, tight, smooth, strong joints between the wrap and the tube. DO NOT apply white glue over the entire back of the wrap-- it will cause wrinkles! They work just great with the edge- applied white glue (about 1/2 an inch in from the edge of the paper wrap).

Next, sand the nosecone tips to the desired shape... You can leave them rather pointy, just "easing them over a bit" (more like a shuttle SRB) or you can round the tips over more and further back (more like a Titan III). It's up to you and how you want the kit to look.

Now here's where I'll add in my bit about hardening nosecones. We all know how easily balsa nosecones can dent or get "smiley faces" and "landing rash" from the usual stuff that happens in flight. This technique won't make balsa cones "bulletproof" but it WILL toughen them up substantially and minimize damage that does occur... You'll need some ULTRA-THIN (water thin) CA glue and something to hold them-- an old paper box lid or equivalent is handy. I also suggest WAX PAPER to line the box bottom with-- you don't want the nosecones to glue themselves to the bottom of the box (ask me how I know this). CA won't stick to wax paper so it works great, and it's cheap and readily available.


First, sand in the final shape you want for your nosecones, obviously. Once you're satisfied with that, grab your CA and your box and take the cones OUTSIDE for this step-- you DON'T want CA fumes in the house! They're pretty raunchy, so I'd DEFINITELY do this outside, because CA hardening releases a LOT of fumes. Also, I HIGHLY recommend you do this CROSS-WIND, with the wind from either your left or right-- if you do it with the wind blowing TOWARDS YOU the fumes will blow right in your face, if the wind is at your back, the wind will curl around you as turbulence and can "whiff" the fumes right up into your face... cross-wind tends to carry them away from you to your left or right.

If you tend to glue things to yourself, I'd also recommend NITRILE GLOVES-- I don't usually have much problem in this regard, so you'll see me working without it in the pics.

Hold the nosecone by the shoulder TIP DOWN and using the tip of the CA bottle, gently squeeze the bottle to apply some CA to the cone, and sort of "rub it on" with the SIDE of the tip, working from the rear shoulder edge of the cone down toward the tip.


Gently turn the cone in your fingers as you work, applying the CA all the way around. Work your way forward toward the tip.


Allow the cone to "soak up" or "drink in" as much CA as it will take... some cones can "drink in" quite a bit of CA, and BEWARE!-- It CAN and usually DOES wick back up the inside layers of the shoulder and CAN glue your fingers to the cone shoulder if you're not careful-- that's why I roll the cone back and forth in my fingertips as I work, and if I feel it starting to stick, I stop applying glue a moment and roll it back and forth in my fingers til the glue cures. Then resume application. If in doubt- WEAR GLOVES!


Apply the glue all the way down to the tip, as much as it will take in. When the cone is "sealed off" the CA will start to simply run down the surface to the tip and drip off... at that point, stop applying glue, and if there's a drop clinging on, daub it off on the box edge or a paper towel VERY QUICKLY (don't glue the paper towel to the cone or the cone to the box edge... )


Set the cones on the wax paper to fully cure the CA... doesn't take a real long time, but a few minutes is DEFINITELY advisable...

More to come! OL JR

 

[luke strawwalker]

So, once the CA has been applied, do the other cones in succession.

Let them cure completely. Then sand them with some 220 grit sandpaper to smooth them out, then sand them with 400 grit to make them REALLY smooth. Then you're ready to primer them-- 2-3 coats of a good primer, all to cure from a couple hours to a couple days, depending on your drying conditions. Sand with 220 grit to take most of the primer off and get the surface mostly smooth, then switch to 400 grit to make it REALLY smooth. Then, if you want a glass-like finish, use some 400 grit dipped in water (with most of the water daubed off on a towel or shaken off) to "damp sand" the primer down extremely smooth. Wipe off the sanding dust (sanding "mud" when damp sanding) and then allow to dry thoroughly. You're now ready for paint.

Back to the build... with the wraps now dry, test fit the boosters to the core. Using a flat, smooth table, align the SRB's with the wrap seams facing inward toward the core along the glue line, and with the core wrap seam aligned to one side or the other with the SRB wrap seam. The vertical alignment of the SRM's should be so that the top edge of the lower black band on the SRM wraps should align with bottom edg of the core body tube. Apply WHITE glue to all the seams and then join the three tubes together, laying side by side on the tabletop or workbench. Leave them level to dry.

More later! OL JR

 

[luke strawwalker]

Here's the three cores joined together...

Next is a novel step part of the kit... a way of doing the motor hook that I've never seen before, but it works...


First, you measure up two inches from the bottom of the core tube. Then draw a rectangle from the measured point down, and a little wider than the motor hook. Using a gentle pressure on the sharp hobby knife, gently cut through the wrap using several light passes with the knife-- DO NOT cut through the tube, just lightly score the paper several times until it's cut through, then remove the strip of the wrap from the tube where the motor clip will go. Cut a slit in the tube at the top of where the strip was removed for the motor hook end to pass through into the tube interior. Next, using THICK or at least MEDIUM CA (using the thin stuff I had on hand ended up with the CA wicking into the paper wrap and discoloring it a bit in one spot) tack the motor clip down tight against the tube-- carefully push the motor clip down so that it lies flat against the tube and the slight curve is held flat by the cured CA.


Next, cut the "clip cover" from the wrap sheet using the sharp hobby knife and a straightedge. Next, coat the entire back of it with white glue, then place it with the gray/white separation line even with the gray/white separation line on the rocket, and gently press it down straight and evenly into place over the motor hook. While the glue is still wet, use your fingernail to gently press or knead the cover down tight against the motor hook and firmly down on the tube wrap. This will permanently lock the motor hook down in place.


Then, using a LONG stick, apply a little white glue INSIDE the tube JUST ABOVE the motor hook-- DO NOT put glue up high in the tube-- just a little down around the tip of the motor hook, just above it. Insert the thrust block ring into the top of the tube, and using a clean stick, push it down the tube gently til it butts up against the top of the motor hook. I inserted a motor right quick to make sure that everything was nice and even and properly positioned-- BUT REMOVE THE MOTOR AS SOON AS ITS INSTALLED, just to make sure that the motor doesn't get glued in place! (Which would adversely reduce the longevity of your rocket beyond its first flight).

Next, cut the fin pattern out of the wrap sheet, then trace around the fin pattern onto the balsa sheet, and cut the fins out with your hobby knife. At this point you can either paper the fins like I did, or you can finish them with whatever your preferred method of filling the grain of the fins is. I rounded the front edge of the fins, then paper them with printer paper, trim them, and have them ready for paint. Since the whole rocket isn't painted, I went ahead and primered the fins and then spray painted them white.

Next, the nosecones, having been hardened, sanded, primered, and sanded smooth, are now ready for paint. You can go with a more "Titan III" appearance, using aluminum for the SRM cones and black for the center core nosecone, or white, or black, pretty much whatever... I went with white on the core "payload fairing" (also with a slightly rounder tip) and aluminum on the SRM nosecones, leaving them slightly pointier than the more rounded SRM nosecones found on the Titan III-- more like the somewhat pointier SRB cones...

Next glue the fins on, (using double glue joints if you want the strongest bonds) and fillet them. Then cut the fin numbers out of the wrap sheet, and coat the backs with a thin layer of white glue, and apply them to the fins according to your preference. Then cut your launch lug in half, cut some small standoff strips of balsa from the excess fin lumber, and glue the launch lugs in place per the instructions.

Make the parachute up according to the instructions. Make the "teabag" shock cord mount per the instructions, precurl it to conform to the tube, and then install it as far down the tube as you can with white glue. Screw the screw eye into the ballasted nosecone, slightly off-center and into the undisturbed wood around the ballast hole, which is sealed up with wood filler (which won't hold a screw eye). Apply a drop of yellow glue and screw the screw eye in place. Tie the shock cord off to it.

The kit is now finished... you're ready to fly on B or C motors. Glamour pics to follow...

Later! OL JR

 

[luke strawwalker]

Here's some pics of the rocket on my Zooch Pad 34-Z, "ready for liftoff"... Enjoy! OL JR

 

[Zeroignite]

Pure small-detail sexyness.

 

[luke strawwalker]

Finally, time for the big first flight...


On the pad, continuity check, affirmative-- missile on internal DC, affirmative...

Counting down... and liftoff!


We have a good chute deploy... winds southerly at 8-10 mph and gusty... drifting northward out of the launch range... touching down over the fence in the sorghum field...



And we have a safe recovery! Altitude 0.1 nautical miles, downrange distance approximately 0.15 nautical miles...

This is a fun little kit, and it'll be released at NARAM. It's a nice flyer and the price is right... What's not to like! Wes told me it should retail for about $15 bucks MSRP...

Have fun and keep 'em flying! OL JR

 

[Dr.Zooch]

Actually... the kit will be released at NARCON 2014 in Cape Canaveral at the end of this month. My brave beta builder Luke typoed it as "NARAM" but with a beautiful build such as he normally does, how can I complain?

GREAT build pix Luke!!! Nicely done! And thanks for keeping the secret for so long.

 

[luke strawwalker]

Actually... the kit will be released at NARCON 2014 in Cape Canaveral at the end of this month. My brave beta builder Luke typoed it as "NARAM" but with a beautiful build such as he normally does, how can I complain?

GREAT build pix Luke!!! Nicely done! And thanks for keeping the secret for so long.

D'OH! My bad... LOL Meant "NARCON"...

You're welcome. Sorry it took me so long to get it done, what with harvest in the middle of it and craziness around here afterward...

Wes is good folks guys-- yall get 'em while they're hot! Neat little kit...

Glad for the opportunity! Yall have a good one! OL JR

 

[NJRick]

this is REALLY COOL! nice to see the "Master" with his build threads! well done Luke...she turned out great! I can't wait to get one!

 

[NJRick]

and I agree Luke...that really is a neat way to do the engine hook! a neat idea!
Dang this Dr. Zooch is smart!:bangbang:

 

[Mushtang]

So when do I get to do a beta build of a Dr Zooch rocket?

 

[Cookie the Dog's Owner]

Ooooohhh, I want one. Always been a Titan fan.

 

[paul.nortness]

Holy crap I haven't seen a Power Pulse in years!

 

[Fred Garvin]

Great work JR! Nice lookin little bird....


Sent from my iPad using Rocketry Forum

 

[luke strawwalker]

Holy crap I haven't seen a Power Pulse in years!

Yep that's like my favorite controller-- after I modified it to use a REAL battery (and one that was actually available-- IE my vehicle battery, or jumper pack...

That and adding LED's for battery connections and continuity, and lamp cord throughout, and you've got a great controller... what Estes SHOULD have been offering all along!

I see they finally have one with SOME of those features, for a whopping price of course. Mine came in a starter set I got decades ago and it cost me maybe $5 bucks in LED indicators and lamp cord from the dollar store to modify it...

Did my old mid-80's Electron Beam in the same mods...

Later! OL JR

 

[luke strawwalker]

Great work JR! Nice lookin little bird....


Sent from my iPad using Rocketry Forum

Thanks... glad you like it! Pick one up! Fun little rocket! OL JR