It’s a great question, the ones I’ve tried light really fast. I was able to light one with just bare nicrome because all the pyrogen was gone. I probably would use old q2g2 igniters which are low current

I tested and with the bolt installed, a lot of air can still get through the center of
The mount. I soaked a bit of paper towel in glue and worked it into the space between the four tubes on the forward end, then covered it in wax paper and turned it over so it would dry flat. After a few hours I pulled the wax paper to let it finish drying.

Attached Thumbnails

   

Today is the day to put the quad mount together, the mid ring was very loose on the fwd 29 mm tube so I glued a strip of card stock on that, fortunately was wide enough to get the fwd ring also. When that was dry the mid ring was glued to end of the tube and allowed to dry, then the fwd ring and spacers were glued on and fillets added. I then carefully marked where the quad tubes will mount to the mid ring. This is a butt joint although there is a lot of surface area, there is an opportunity to strengthen the mount with split bamboo glued in the valleys of the 18s, passing through to be glued inside of the 29mm fwd tube. This does double duty since it closes the remaining gaps. Each piece was glued and held in place while it dried, then filleted. Last, the centering ring for the quad 18’s goes on and is spaced two inches from the fwd ring with a spacer that was on the laser cut cooling fin and spacer set. Last shot is the complete mount with the cooling fins dry fit.

Attached Thumbnails

                   

Next up will be the interchangeable 29mm mount with integrated decorative cooling fins. I first scanned the parts in case I need to reproduce this in the future. Not in the scan is a 29mm tube and a motor block.

Attached Thumbnails

   

I used 4 engine hooks, which work pretty nice, since they're all on the inside. Your method looks good too, though - I've done that with clusters, and makes for more solid retention than hooks.

__________________
Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

I've done 2x clusters of Q-Jets, so far so good. I'm going to try mixing Q-Jets and BP next.

__________________
Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Nice! This is kind of stalled since my water heater is leaking, will get back to it after it is replaced.

At today's club launch, I put up my Estes Saturn V on 5 motors - 1xD12-3, 2xC6-0, 2xC12-4, all lit immediately. It was interesting seeing the black smoke for the first half burn, then changing to white after the Q-Jets burned out. It was noticeably quicker off the pad than with 4xC6 outboards (weighs 19oz w/o motors). I've had weak ejection problems on a couple launches, only 3 motor tubes extend to the chute compartment. Adding a bit of BP to the C12 ejection wells really got the chutes out quickly. I think this will be my motor combo going forward.

__________________
Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Great combo and great news, did you use the stock qjet igniter?

Scanned the rings I enhanced for the 24 mm mount and glued it together. As before, I’ll leave the cooling fins off for paint.

Edit: The gap between the decorative 29mm sleeve and the 24mm mount bothered me. I didn’t want to add a lot of weight ,so I cut a sliver of 24-29 mm centering ring. Slit it for the hook, and worked it into the gap. It didn’t need any glue but I wiped some CA on the joints. Again this one is waiting for paint.

Attached Thumbnails