Clear Plastic - TIP

Sometimes I cut out and save pieces of clear plastic off vacu-formed packaging.

On a rare occasion you might need a piece of clear plastic for a window like on the Mercury Redstone Capsule.
The packaging plastic isn't thick enough for clear fins unless you are making some Micromaxx sized models.

Estes R2D2 #2142 Build, Part 8, Parachute, Shock Cord & Fins

The 12" parachute is assembled as normal.
The instructions have you loop the shroud lines around the mount then pull the canopy through the loop. This will make some tangled shroud lines.

For a tangle free parachute I tied some small loop knots at the centers of the shroud line loops.
A heavy line was fed through the loops.
This outside line was tied around the engine mount and taped.

The 36" elastic shock cord was tied on the upper end and taped.
A second 18" shock cord was included in the kit and isn't used.

This is a rear eject model.
The parachute folds and is set around the interior engine mount tube.
The shock cord wraps around the parachute.





The other end of the shock cord is tied to a plastic loop at the bottom of the body.
With the shock cord attached the engine mount doesn't slide in very easily over the lower plastic centering ring. I'll have to file a notch to allow the shock cord some relief.

Don't dry fit the clear fins!
The fit on the pin is so tight I had problems getting the two pieces apart to get some glue in there.
You only have to apply glue to the pin and press the fins in place.

FlisKits MMX Crayon Build Part 6, Fin Glue and Shock Cord

Line up the launch lug on the marking guide and mark for the fins.







A thin line of paint was scratched off for better adhesion.
The scratched line was just a little shorter than the root edge of the fins.

A drop of medium CA was set down on a scrap piece of cardboard.
Just the root edge of the clear fin was dragged through the drop.

Set the fin on the scratched line.
Start with the corner of the trailing edge even with the end of the tube.

The other end of the shock cord got an overhand knot.
There isn't enough room between the engine mount tube and the inside wall of the BT-3 crayon tube for a full square knot.
This overhand wrap will hold the Kevlar when it is set into a glue fillet at the base of the upper centering ring.

The streamer is taped onto the Kevlar line.
I try to arrange the model so the upper section won't be swinging and hitting the fins or engine mount when the model is hanging by the streamer.

The 12" streamer might be a little long, we'll see how easily it slides out of the upper section.
When prepping for flight, put the shock cord in the upper crayon section then follow with the rolled up streamer. At ejection the shock cord will be above the streamer and help pull it out.

FlisKits MMX Crayon Build Part 3, Fin Cuts and Fill

The fin pattern seemed pretty large, I scaled them down a bit.

I've lined up the edge of the clear stock with the root edge of the pattern.
There's no need to cut all the way through. Score the plastic and crack the plastic apart.





The model has three fins.
You have plenty of extra material left over. Cut out extras and keep them handy.
These fins are very thin and super glued on the body tube.
There's not much of a root edge, they could pop off on a hard landing.



The balsa nose cone shoulder edge was rough and needed to be built up.
Some filler was brushed over the edge. The nose cone was pressed and turned into the tube end forcing the filler into the shoulder. Pull out the nose cone and you can see the lip filler is raised over the side.
After sanding the shoulder should be more squared off.






I went ahead and filled the tube seams.

The small lug was set over a toothpick tip and filler brushed on.

260 Space Booster Build Part 15 Clear Fin Glue Test

I cut a 4" section of the clear fluorescent light protection tube for fin gluing practice. I wanted to find the best way to adhere the thin fin material.

Going back to the ole Estes Gemini Titan instructions, you would use clear dope to glue the fins.

I applied a line of dope to the root edge of a practice piece with a Q-tip. This gave me good control of the flow of the dope.

When set on the clear tube, it did adhere pretty well.

Using more practice pieces, I tried other methods.
We didn't have Super Glues when the Gemini Titan and Thor Agena kits first came out. I tried thin and medium CA fillets.
The thin CA fillet worked okay, but the medium CA fogged up the root edge when it dried.



I even tried clear "invisible" tape pushed into the root edge. It wasn't invisible. But applied to both sides, it had the strongest joint.




In the end, I'll probably go the old Estes route.
Clear dope on the root edge, then a clear dope fillet applied with a Q-tip or small brush.
The clear dope fillets looked the best, it did dry transparent and without fogging up the plastic.
These clear fins will probably pop off on a hard landing, just like they used to on my Estes Thor Agena B.

260 Space Booster Build Part 14 Clear Fin Cutting

After the one side is scored over the fin drawing, the plastic is removed from the template and flipped over.

The other side is scored. Cut right over the first line, you can see it right through the plastic.
Be sure to extend your cut lines beyond the fin shape to the ends of the plastic piece.





Flex the plastic score lines over your finger.
Scoring on both sides should give you a pretty clean break.







After sanding the edges down with a block, here's all four fins ready for the clear body tub wrap.

260 Space Booster Build Part 13 Cutting Clear Fins

Cutting out the fins took practice and some wasted clear fin material.
This clear fin stock from Hobby Lobby is thicker and harder that the old Estes stock.
To start, the instructions were taped to my cutting board. The clear fin stock was taped over the fin drawing.
On the first attempt, I scored just one side of the fin stock using a sharp knife and straightedge. With the older Estes stock, you could simply score and crack it down the cut line.



Here's how the cut line broke.
The crack strayed off the score line.
I'll have to score the edge lines on both sides of the plastic.




To have better control cracking on the scored lines, cut your fins from a piece of plastic just a little larger than the pattern, maybe 1/4" clearance on all sides.