Pop-and Go, Passport, Direct Staging Estes D Motors
 

What's your favorite method?

I removed the fins from the attached drawing. The booster airframe is 8" long. The black line is where the booster meets the sustainer. Both stages use Semroc LT-125 for the airframe. The blue tubing in both stages is a 5.5" piece of Semroc LT-115 that slip fits into the LT-125. The purple inside tube is a coupler made from LT-115 that is 3.5" long and has 2" bonded in the booster and the other forward 1" is what couples to the sustainer. The coupler is butted between the face of the forward centering ring in the booster and the face of the rear centering ring in the sustainer, the mentioned centering rings are positioned in such a way to accomodate the coupler. All the red parts are Semroc 24mm components.

If I can find an F100-0 to use for a booster motor and an F100-8 or 10 for the sustainer I'll eliminate the Semroc 24mm adapter parts in both stages ..... but I am currently planning to use Estes D12 motors in the booster and D12 or E9's in the sustainer because they are readily available.

So, what's your favorite staging method for this application? I can't tape the motor together as with direct staging. It's fairly small diameter airframe tubing with D motors in each stage. Should I extend the lower 24mm motor mount so the upper stage motor can plug directly into it or so the 24mm motor mount in the booster and sustainer when assembled butt up against each other? I don't think a 1/4" Passport hole in the 24mm mount would help much in this design since the coupler is so long, it doesn't seem like it would vent much before coming apart.

The original design used 29mm Mini-Max PB "F" motors and I think those were 7.75" long so my guess is the original was probably direct staged with the motors taped together. I have all the parts to build it (Thanks Semroc :D )and I only need to cut the sustainer fins and then I'm starting construction. Please don't ask what this rocket will be ..... it's a surprise (It's not the Sonic 36) ;)

Any and all suggestions are appreciated and I'd like to know about your experiences.

Thanks

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I'd try what I call "fuse-staging"; have a piece of waterproof cannon fuse in the nozzle of the upper motor with the end touching the top of the booster motor grain. The fuse is consumed very quickly, and assures good ignition of the upper motor as it is in the nozzle touching the grain.
I have done this several times and it has worked great.

"What do you use cannon fuse for?" (Bill asks, setting up this classic movie punch line..........)

Pass-port and gap-staging worked fine for me until the B4-6 motors ran out. I've had two failures to ignite the sustainer with the B6-6. The last two MS flights of mine have been with the Estes direct staging using B6-6's and they staged fine. I think I'm going to start augmenting my sustainers with a piece of old sure shot for pass-port and gap-staging.

The old "thermalite based" sure shot is even better than cannon fuse for instant, almost guaranteed upper stage ignition.
Too bad thermalite wick is one of the numerous items the Gestapo, oops...I mean BATFE, has eliminated from the average rocket hobbyist's available items.

Remember when you could get that stuff by the roll from HPR companies like LOC, THOY, and Magnum?

Yep, sure do & I'm not aware of any US Citizen hobbyist rocketeers using it for anything other than legitimate, safe hobbyist purposes either.
Go figure....

Thanks guys for the suggestions. It's been a good while since I've staged anything with black poweder motors and come to think of it I remember having success with fsi motors both direct staged with one wrap of scotch tape with the supplied thermalite igniter installed in the upper stage motor, and with a gap between the stages but still with a thermalite igniter in the upper stage. It would seem the consensus here is to have an igniter in the upper stage motor to .



YES! I remember buying a 30M roll of the pink thermalite (slow-20 sec/foot) from Ross at an LDRS launch right off the back of his truck ..... and we all know we'll never see that happen again. Unfortunately I used the last of what I had around 1994. You may remember the Robby's Rockets cluster igniters were flash bulbs with several long whips of thermalite enclosed in teflon tubing with a shrink wrapped single whip attached to that and the bulb. I had some of those and just cut them up into single igniters until I ran out for good.

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..... and most recently eliminiated the ability to replenish any QuickBurst igniters to average rocket hobbyist's range boxes. I used David's QuickBurst "hot shot" low current igniters exclusively to ignite my clusters of Estes D12's because they fit perfectly in the nozzles and ignite a cluster of BP motors instantly.

I have enough to last me through the fall flying season with my current projects but after that I may have to look into dipping my own with one of the Magnelite pyrogen or similar kits, unless those disappear as well .....

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It wasn't Thermalite . . .

Centuri "Sure-Shot" igniters were Jetex wick with a piece of bare Nichrome wire wrapped around it.

FSI / Flight Systems igniters ( not the BP-100 Electrice Matches ) WERE Thermalite ( Nichrome wires spiralled around the wick, with reinforcing fibers ) !

Dave F.