Wednesday, October 29, 2014
The joint seam was already sanded smooth and filled with CWF and sanded again.
After that some medium CA was applied with a Q-tip and the excess wiped off.
The tube was shot with a coat of primer/filler.
the inset picture shows the tube after sanding. The white area right below the joint is the sanded CA glue.
The ends matched up well.
TIP: After the tube is marked for the four fins, turn the marking guide 90 degrees to the next fin mark. The "Star" marking is the launch lug line. In the inset picture you can see the star turned to the right, 1/4 way around the tube.
Sometimes a kit supplied marking guide can be off. This is a simple way to check if it is drawn correctly.
Build time: (Some items below weren't covered by pictures in this build)
Body tube seam fill = 10 minutes
Sand body tube seam filler = 10 minutes
Fill launch lugs and sand = 10 minutes
CA coat tube edges = 5 minutes
Spray primer = 5 minutes
Sand primer smooth = 20 minutes
Total build time so far = 3 hours 15 minutes
Tuesday, October 28, 2014
It's important to leave the tie down lug on the nose cone base. I like to tie a line so if the nose cone comes off at ejection it'll still stay attached to the model.
A fine tooth razor saw was used to remove most of the base.
A round file rounded out the corners. A tear could start from a sharp inside corner. Rounding the corner keeps the base strong.
Here's the finished open nose cone base.
The curved edge is retained.
Notice the inside corners are rounded.
As the mount was pushed in, it was turned to even out the glue ring already inside the tube.
I used the flat sanding block against both tubes to be sure they were even.
With this now a D engine model, a 3/16" lug was used in place of the 1/88" lug.
I set the lugs over two Q-tips for a handle when the CWF filler is brushed on.
Sand N.C. seams and fill low spots = 15 minutes
Remove and smooth N.C. base = 15 minutes
Glue in engine mount = 5 minutes
Total build time so far = 2 hours 15 minutes
Monday, October 27, 2014
The matte board disk was punched for the shock cord tie.
In the center a rectangular second piece was glued on for more support.
The disk was glued over the top edge of the coupler.
Any overhanging edge was sanded flush with the outside diameter of the coupler.
The coupler and end bulkhead assembly was glued into the yellow tube and fillets applied.
Make coupler bulkhead = 30 minutes
Total build time so far = 1 hour 40 minutes
Sunday, October 26, 2014
I'm using the yellow section as a altimeter and payload section.
I'll have to make a coupler with bulkhead out of the second red coupler.
The red coupler fit can be tight so the edge that goes into the lower BT-60 section was rounded on the outside.
After rounding the edge got a coat of medium CA.
The edge was smoothed again with 400 grit.
Here's how the red coupler will fit into the upper white tube.
The coupler isn't glued in yet.
The red coupler is 1 1/2" long.
Instead of gluing it just halfway in, I want a little more length into the lower white BT-60.
5/8" will be glued into the upper yellow section, leaving 7/8" below.
A pencil tracing was made on heavy card stock around the outside diameter of the coupler.
This matte board is thick but can still be cut with scissors.
CA tube ends = 5 minutes
Trace and cut disk = 5 minutes
Total build time so far = 1 hour 10 minutes
Saturday, October 25, 2014
The small holes are punched for the Kevlar tube. On the right the larger circle is for the engine hook movement.
In addition there are lines drawn for some reinforcement gussets.
This will be a D engine mount, I wanted it stronger than just the two centering rings.
Reinforcement gussets were cut from the excess 3/32" thick wood stock. Cut them longer than needed and sand to a good fit between the rings.
They are cut higher than the height of the centering rings for trimming later.
At the bottom you can see the Kevlar guide tube in place.
After the glue dried on the four gussets, they tops were sanded flush with the outside edges of the centering rings.
It's pretty surprising how much stronger the entire engine mount is with the gussets added.
Check the fit in the BT-60 tube before gluing. The gussets will require you to sand the rings a bit for a sliding fit.
Assemble Engine Mount = 15 minutes
Add gussetts and sand = 15 minutes
Total build time so far = 1 hour
Friday, October 24, 2014
To enlarge it for 24mm engines:
Trace around a BT-50 tube. I used a heavy walled BT-50.
After you trace the line, look at it closely to be sure the circle is centered. If not, erase and try again.
Sometimes it takes a second try to get it right.
Note: There is only one card stock piece in each kit. I am building two Patriot kits.
To get the new diameter fit close, cut slightly inside the pencil line.
The line you traced in the first step is just outside the tube diameter.
With all cutting, don't try to cut through in one pass.
A few lighter passes is better than a hard single cut.
If it is still too small, widen the hole with some 220 wrapped around a finger.
Sand a little and check, sand and check again.
Cut 50/60 rings = 10 minutes
Total build time so far = 30 minutes