Enerjet by Aerotech Strong Arm Build, Part 17, Adapting A Painting Wand

I use painting wands to hold my rockets horizontally when spray painting.

The wand is a 1/2" dowel shoved into a used 18mm engine casing. 

This is too small a diameter to fit this larger rocket engine mount.

I wrapped some corrugated cardboard around the casing and closed it up with tape. To fit the 29mm diameter mount, the cardboard is just over a full wrap around the casing. This wider diameter gives a good friction fit. 

With the dowel wand slid into the mount,

Some masking tape is placed sticky side out inside the main body tube.

A rolled up paper towel is press into the area around the mount and up against the inside wall of the main tube.

Any open areas are covered with additional pieces of masking tape.

Now the rocket can be spray painted without getting any paint inside the low end.

Enerjet by Aerotech Strong Arm Build, Part 16, Setting The Lowest Centering Ring

I'm back from vacation, hoping to paint the lower body assemblies - but, it's been raining! So, onto other steps.

 

Check both sides of the centering ring, pick the smoothest side to be exposed out the bottom.

On one side, there was a chip. I marked this side with "X's". This side will be facing up, not seen. 

The low edge of the body tube is slightly "squared", out of a perfect round. The four fins are locked into the rings and pull in the body tube. 

It would be very difficult to "slide" the ring in with the tube slightly out of round. 

On the left, I sanded an angle into the edge to make the insertion easier.

Notice the laser charred edge has been sanded.

The center of the ring also got a taper to slide over the engine mount tube.

The ring is slid in and rests against the root edge tabs of the fins.

Here I've applied a wood glue fillet around the ring/tube joint.

Enerjet by Aerotech Strong Arm Build, Part 15, Nose Cone Re-Paint & White Paint

The nose cone color was picked to closely match the upper roll bar on the sticker sheet.

An earlier post showed bubbles as the nose cone paint dried. 

I usually don't use Rusto spray paint but this gray was the closest.  This time, the spray coat was even and glossy.

The rest of the body is painted a gloss white with no masking.

Here's the body after a light first coat. Sanding followed with 400 grit.

Enerjet by Aerotech Strong Arm Build, Part 14, Launch Lug Fit & Fillets

While the fit of the vane sides were pretty good, the edges could still use a fillet.

I used Titebond Quick and Thick with a smaller Elmer's glue bottle nozzle. 

TIP: On a long fillet like this, it's easier to glue and smooth about half of the length, then do the upper half. Too much excess glue can pool under your finger when smoothing out a long fillet. 

GOTCHA: The coupler end inside the upper slot prevents the front of the launch lug from fully seating.

I filed down the front half of the positioning tab to fit over the coupler.

Beacon Fabri-Tac was used to glue the launch lugs in position.

A piece of masking tape held it down while the glue sets up.

I'll be on vacation for the next five days, there may not be posts while I'm away.

Enerjet by Aerotech Strong Arm Build, Part 13, Gluing The Vanes

 

With the low end tip of the vane set at the tape wrap, 

the vane is pressed in place down the pencil line.

Hold the vanes in place with tape as the glue sets up.

Go back and check the alignment to be sure there wasn't any movement. Epoxy is slippery!

Check the edges for any glue that may have squeezed out.

You can pick it up with a Q-tip.

I'm building three of the Strong Arm kits, you might notice one build with no seam fill or filler primer.

On one build, I glued the vanes on using Fabri-Tac with good results. Fabri-tac takes a while to dry, the bond felt as strong as the epoxy joints.

I had a few vane tips that ended up raised.

In the top picture, you can see the open end.

Here, I've used a wood glue fillet to fill the gap.

Enerjet by Aerotech Strong Arm Build, Part 12, Setting The Vanes

The rear of the vanes are 2" from the front tip of the fins.

Instead of using the wrap around guide, I got out my aluminum angle.

It's pretty easy to draw a pencil line, extending from the front leading edge tip of the fins.

I made a 2" mark on the angle and transferred that onto the body.

For position consistency, 

I pencil marked an even wrap of masking tape.

The low end of the vane will be set just above the tape wrap. The picture shows a dry fit.

I tried using CA glue on the back of the vane to adhere it, but there wasn't enough surface contact for a good bond. I've got to use epoxy. It'll flow and fill some voids.

15 minute epoxy was spread on the underside of the vane using a Q-tip stick with the cotton end removed. 

To even out the epoxy bead and prevent squeeze out beyond the edges - 

I wiped off the sides with a folded paper towel. This evens out the bead over the entire length of the vane. 

The even center bead result is shown on the right.

Enerjet by Aerotech Strong Arm Build, Part 11, Fin Fitting

Earlier - 

The lower lock ring (on the engine mount) had to be moved forward 1/2" to be in the correct position for the rings to sit just outside the end s of the fin slots. This also set the engine mount to be flush with the main airframe tube.

Try as I might, the low end of the TTW tab would not click into place.

To fit into the new position of the lower lock ring, the inside notch had to be cut 1/2" up from the bottom. On the left, the notch to be cut is marked with pencil.

On the right, the notch was cut with a razor saw.

A  CA glue bead is applied to all contact points along the root edge. 

 

These fins take a little bit of effort to snap them into place.

Experience has taught me - 

Snap in the front first, then snap the rear tab into the rear ring.

TIP: Place your thumb into the engine mount tube for support while pushing down on the fin until it clicks.