3 stage park flier

Hello,
I'm considering building a 3 stage park flier to make use of my stock of A10-0 motors, however with the announcement by Estes that they will be bringing back the A8-0, I decided to modify it to use 18mm boosters and just use adapters for my A10 motors. I've attached the Rocksim design and would appreciate any comments the group may have. My question is this...if I stick with the 18mm booster design, there will naturally be about an inch to an inch and a quarter gap between the booster motor and the motor above it. Given their small size, are booster motors reliable for gap staging? (I do plan on cutting a hole in the stage couplers to allow for a bit of venting to aid in the upper stage ignition.)

I'm beginning to find scratch building addictive...it's a lot of fun to design models that are optimized to meet my motor inventory!
Craig

View attachment mini engine stager.rkt

caheaton said:

Hello,
I'm considering building a 3 stage park flier to make use of my stock of A10-0 motors, however with the announcement by Estes that they will be bringing back the A8-0, I decided to modify it to use 18mm boosters and just use adapters for my A10 motors. I've attached the Rocksim design and would appreciate any comments the group may have. My question is this...if I stick with the 18mm booster design, there will naturally be about an inch to an inch and a quarter gap between the booster motor and the motor above it. Given their small size, are booster motors reliable for gap staging? (I do plan on cutting a hole in the stage couplers to allow for a bit of venting to aid in the upper stage ignition.)

Click to expand...

I would trust gap staging over any other method. It was the MIRV Gryphon, an interesting kit in which a cluster of four 13mm boosters staged to four separate sustainers, which introduced me to gap staging, and proved a good deal more reliable than the tape-staged Estes Mini-Cobra.

I'm beginning to find scratch building addictive...it's a lot of fun to design models that are optimized to meet my motor inventory!

Click to expand...

You've just taken the first step into a much larger universe. It's generally more fun to build what you want rather than what someone else wants.

Is there any way you could post a non-rocksim drawing?

I have not yet entered the rock-sim age.


.

ditto

the Old A3-Ot and A10-0s are great gap staging motors. A8-0's will be 18mm as you mentioned and are also an inch longer so you'll be gap staging weather you won't to or not if you use A10's in your lower stages.
Vent holes in the couples is what i've done in the past.

I sure Hope you have a BIG park, even with 18mm boosters your gonna get some serious altitude, and LONG drifts even with streamer recovery.

I was SHOCKED at how high and Far my MiniManche 3rd stage went on an A10-0T, A3-0T, 1/2A3-4T combination! the Streamer recovery 3rd stage ended up in a School parking lot almost a mile away

I haven't built it yet, but attached is a jpg generated by Rocksim. Basically, it's built around Bt-50 body sections. Each booster is 3" in length and the sustainer is 10" in length. As far as altitude, it's fairly modest for a mult stager. Rocksim predicts an altitude of 1073' when flown with a B6-0-B6-0-1/2A3-4T combination and only 445' if flown 2 stage on an A10-0 to 1/4A3-3T. If I fly it with the A10-A10-1/2A3 combination it reaches 813'...near the limit for a nearby park I frequent. Surprisingly to, the B6-B6-1/2A combo still gives a liftoff velocity of 46fps, even though the bottom stage is only a B6.
Craig

caheaton said:

...if I stick with the 18mm booster design, there will naturally be about an inch to an inch and a quarter gap between the booster motor and the motor above it. Given their small size, are booster motors reliable for gap staging?...

Click to expand...

I use adapted A10-0T motors in my Centuri Stiletto clone, and they've worked fine, so far. I've always used an A8-5 upper stage, its large nozzle probably helps too.