Nytrunner
Pop lugs, not drugs
That's a Lot of fin real estate to finish. Bondo and a rotary sander?
That's a Lot of fin real estate to finish. Bondo and a rotary sander?
I’ve actually set up a gofundme page to help pay for all of the bondo and sandpaper i will need to finish this: www.gofundme.com/bondo
I've been Rick Rolled...
I aligned the CR to the Aeropack retainer as closely as I could visually, but I'm running a small risk here as I don't have a 98 mm hardware set that would allow me to remove any alignment error.
Use the mount tube. put strips of tape at 120 degrees till the retainer is centered. mark drill holes accordingly, when you've got a couple, you can use them to hold it in place for the others.
Alternatively, I could eliminate the switch band altogether. If I have a coupler bonded inside the booster section that the avionics compartment can sit on, do I still need a switch band?
No. You can mount the switches in the forward end of the booster body tube, but where are your parachutes, ejection charges, etc?
Sorry, my post wasn’t clear. I would keep the avionics bay inside the coupler that joins the booster section to the payload section. The only change here is to remove the switch band from the avionics bay. To help compensate for the fact that the avionics bay no longer has the switchband to carry the launch load, i would bond in a short section of coupler into the booster section which would act as a stop for the avionics bay.
Can fiberglass and epoxy adhere well over bondo? My intuition would lead me to do all my bonding and fiberglassing, then deal with filling in unevenness
Thanks, that’s what confused me. I thought you said you would bond the entire coupler into the aft body tube.
That would work.
For future reference, I glass full length tubes and cut the switch band from the glassed length.
You could cut the switch band first and put it on a coupler, then put the coupler into the remaining length of body tube, glass the assembly, then cut the glass cloth where the band meets the rest of the body tube once the epoxy reaches leather, but it would be really tricky not to glue the coupler in place.
I can do that - this is my first time fiberglassing a cardboard airframe, so I am open to suggestions here. Theoretically, I could just sand off all of the fiberglass layer I applied then apply multiple layers of cloth and epoxy in one sitting so that the epoxy adheres better, but given the tailcone shape, and the point of the fiberglass layer is to provide impact resistance from hard landings, I don't know that the layer to layer adhesion is as critical.
Either way, I can certainly apply the second fiberglass layer and then fill in with bondo - that makes more sense.
Thanks for the suggestion, Steve. I'm considering doing this with the glassed payload tube. My only hangup is that I normally use the miter saw to cut tubes, but the 7.5 inch tubes are too large for the saw to get all the way through in one cut. I could use the miter saw with two cuts and then use the odd discontinuity that inevitably results as an alignment key, but that may look funny. Is there a strength reason to laminate the switch band?
Not everyone has a table saw but this simple jig works real well. I cut any size tube that doesn't fit in the miter box. I hear different ways to cut FWFG tubing but I cut everything with fine tooth carbide blades. G10 fins on the table saw. When I cut the FG tubes I place 1 wrap of blue tape at the cut line, it hardly splinters at all if you feed real slow.I don’t know what kind of miter saw and stand you have, but you may be able to clamp a block to the stand or bench that the saw is bolted to, put one end of the tube against the block, then lower the blade, and turn the tube to feed into the running blade. That’s better done on a table saw and John Coker even did a project to do that with a diamond embedded tilesaw just to cut tubes straight.
https://www.jcrocket.com/tubesaw.shtml
No, it’s definitely not necessary to glass the switch-band.
I have cut tubes by hand using a wrap to mark the line and a hacksaw, followed by marking high spots and sanding with a sanding block or using a rasp. It actually goes very quickly and yields good results. Nobody can see it from the flight line anyway. [emoji6]
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