Currents_projects

I used the lower fins as guides for the upper fins. The root of the fin get West Systems epoxy all but the top and bottom which get a little dab of super glue to hold the fin in place while the epoxy is drying.

This wasn't easy to do. The first time around, i tried normal S-glass cloth and wetted the inside of the tube, that didn't work, as the cloth fell off, got mad and ripped it all out. Tried again with the carbon, but wetted the cloth on the table first, then rolled it up and placed inside.

Got out my knife and cut out the part with air bubbles, then used my Dremel tool to sand out the cut parts. I found some bigger balloons in a kids assorted bag of balloons. This time i mounted the coupler tube vertically, better but still had to work the cloth to get it flat all around. So now this coupler tube has 1st layer of 5.5oz 4HS carbon fiber, 2nd layer 6oz S-glass. This should be strong enough.

I got my first use out of the FoodSaver Vacumm system, which is meant for food etc. Each plywood ring and bulhead got a layer of carbon fiber on each side, release film on each side and thick breather cloth on each side, then the air is sucked out of the bag pushing the carbon tight against the wood and removing excess epoxy.

Ring gets epoxied on motor mount just above the upper fins. I should have done this before i started the fillets on the fins.

The Foodsaver worked great, but it pressed the carbon cloth to the side of the plywood too, so i had to use my Dremel tool to remove unwanted carbon on sides, what a dusty mess.

Got some rinkles, had to sand and apply patches.

After sanding and patches, I decided to do the third layer by hand. Turned out good.

The 6" tube got some West Systems 410 fairing compound to cover the cloth weave and give a good finish.

See the phenolic tube layer with the carbon and two layers of S-glass.

I cut the fin slots with a Dremel tool and a Gyros saw blade that work in the Dremel. I found it was best to score along the line with one blade till i went thru the layers of glass. Then attach a second blade with spacers to have the width of slot I need, score the double blade using the first scored line as a guide. Do this until the second blade goes thru the glass layer. Now go back to one blade till cut all the way thru. I also drill a hole at the upper most part of the slot.

I glued a 1/4-20 blind nut to a square of coupler tube, then glued the assembly to the inside of the body tube, using the screw to line everything up. I coated the screw with Olive oil so no epoxy would end up on the threads.

This is looking down on the motor mount tube with a centering ring temp placed while epoxy w/ milled glass fibers cures around the middle centering ring. I have placed two pieces of nylon strap on either side of the motor mount. These straps will be long enough to go thru the forward bulkplate with the u-bolt, so that i will never lose the plate. I was going to us redi-rod, but I wanted to keep the weight forward down.

Waiting for the epoxy w/ milled glass fibers on and around the centering ring above the upper fins to cure. I have a 6" hose clamp around the tube at the bottom, as with the fin slot there is a little play around the bottom ring.

A 1/4-20 blind nut mounted to a piece of coupler tube then the assembly epoxied to the body tube.

I tape a small disposable bush to a wooden dowel, then paint some un-thickened epoxy inside the tube wall and fin. Then i tape a tongue depressor to a dowel and scoop thickened epoxy(glass bubbles/milled fibers) and try the best to get the stuff inside. It can get messy, that's why I put masking tape where the rear ring will go, as I have not done this in the past and have had to grind the epoxy off so the ring will fit.

I will be aplying some 410 light fairing compound later, so you don't see the weave

It makes it easier to work on the internal fillets standing up, and looking into the mmt at eye level.

These are more for appearance than strength. Having a rounded corner helps later with the carbon cloth fin to fin.

Two rings are clamped together, top one is for the 98mm to 75mm adapter, and one below it and hard to see is the rear mmt ring. Small holes are for 4-40 t-nuts to hold in the motor, and the bigger holes are for 8-32 t-nuts in the main mmt ring.

The lower fin is about 1/8" larger than the upper fin. The upper fin's tip is not parallel to the root of the fin. I didn't have time to ship them back to PML, so I sanded them down till they are parallel to the body tube.

After sanding and removing the end caps

After removed the excess foam

This was more for looks, as plain plywood is ugly. I even put carbon on the 1/2" side of the ring. Sanded the whole works and painted some epoxy on to make it look good

This will be the upper most button. This inside the coupler with the U-bolt for the lower section of rocket

The nosecone phenolic shoulder is quite thin, so i put a layer of carbon fiber inside the shoulder and fiberglass nosecone.

Has 8-32 holes to secure to main 98 mmt, and 4-40 blind nut to secure the 75mm Hypertek motor retention plate.

Some minor sanding before painting still needed

Wirewrap pins for BP charges, and square u-bolts for 2" strap to pistons

These will be epoxied in the nosecone bulkplate for future threaded rod as weight if ever needed