Estes Big Bertha Build 2

So we got back from Hocking Hills just fine. On the way we swung by Home Depot to pick up an LED work light and some white & gray primer (Rustoleum Painter's Touch 2X). When we got home I opened my eRockets order - the 13mm motors and the Semroc Farside-X kit. But I stayed busy on the eRockets site - now a display cradle, three 18mm display stands, Rustoleum yellow & orange paints, NewWay Skyrise & Flatboy kits as well as an Odd'l Pigasus kit are now on the way. I'm incorrigible. 

So I mixed up some VERY thick CWF and coated all the fins:

Then I got busy with other stuff and let the fins dry for a few hours. I really did put the stuff on thick and it was a lot of work to sand it all off, producing enormous amounts of sanding dust. Then I added more water to the CWF and coated and sanded a second time. I sanded with 220 grit each time. Then I thinned the CWF a final time and gave the fins a final coat. They're drying right now. I plan on doing the final sanding with 400 grit sandpaper.

OK I'm back, having worked some more on Big Bertha in the meantime. Here are my finally finished fins:

They feel absolutely smooth and I hope that proves true when I paint them! But you know, despite the fact that they feel smooth, I think I'm going to continue spot-filling and sanding (more gently, perhaps) these until the actual color is uniform. On close inspection I see areas that still look like bare balsa, though they don't feel like bare balsa.

I got, IMHO, fantastic airfoil leading edges using the North Coast Rocketry sanding jig. Here's what one looks like:

They come in small, medium & large. This is the large, for use w/ 1/8" balsa. You fold a piece of sandpaper (grit not specified, I used 220) and for the leading edge you put the crease in the sandpaper in the right-hand side, insert the fin & sand to shape. I'm uncertain if a photograph will show how nice they came out, but I'll try...

All four look pretty much the same. The left-hand side of the jig is supposed to be for trailing edges.

At this point I referred back to the instructions to resume construction of the kit in the specified order. Kids, if you're reading this blog to learn how to build a model rocket - find another blog! And does your mother know you look at this kind of stuff on the Internet? 

Unsurprisingly, the build pretty much exactly parallels the Baby Bertha. I chose to exclusively use Titebond Quick & Thick glue for this build:

I hope it holds up ok! I like this glue because it's very easy to work with and runs only reluctantly. Anyhow the instructions have you assemble the motor mount as usual:

Next I made little tick marks at the base of the BT for the fin lines:

Then extended the lines, again using my Estes Ultimate Body Tube Marking Guide:

Above, I'm getting ready to draw the launch lug line.

Next I got all excited because I thought it was about time to glue the fins on! But I forgot that I needed to glue the motor mount in first, which I did (interesting photo later). Then on to gluing the fins! But no, darn it - I forgot about filling the body tube spiral. Actually the groove doesn't look too deep:

One article suggested packing the groove directly with straight CWF using a toothpick. Lacking a toothpick, however, I reverted to a modified version  of filling the groove with thinned CWF and a hobby blade - I used the blade part of a little putty spreader. Here's the result, drying:

Another blog mentions a second, subtle groove that runs between the prominent one that should also be filled and sanded. But I rely on the feel of the tool against the groove to direct my application & there's nothing to feel with this second groove. So I'm choosing to skip this and we'll see how the final product looks after priming and painting.

Final bonus photo - from this pic, who can spot the fatal flaw in my build?

OK I'm off like a prom dress! See you next time!