Staging MicroMaxx

[Antares JS]

So, I've tried flying my Fliskits Doubles twice now and both times, the sustainer failed to ignite and the rocket lawn darted. I am using an NE motor in the booster and taping the motors together per the instructions. I've seen other threads swearing this works, but with two failures now I'm starting to wonder if I should sprinkle a few grains of BP down the forward end of the booster or use a wire to dab a tiny bit of quickdip in the nozzle of the sustainer.

I'd like to hear about other people's experiences staging Micromaxx motors and see if there's anything I can do to make this a bit more reliable.

 

[GlenP]

I have not tried to stage MMX, but when I have had an ignition failure with a 13 or 18 mm motor, to help ensure proper ignition next time, just single stage, I will take the smallest drill bit in my set and lightly spin it with my fingers to expose new black powder in the nozzle, in case there was some charred material left over from the ignition that misfired. Not sure if you can find a drill bit small enough to lightly scratch the surface of the powder in a MMX nozzle, or if that technique is considered an engine modification and against NAR safety code. Maybe that might help a sustainer to light as well?

 

[kuririn]

I've launched the Doubles twice, both times the sustainer motor ignited.
Glen's suggestion about scuffing up the BP couldn't hurt.
The nozzle is so small you would probably have to use a needle or pin.
An ice pick is too wide.
The booster motors' delay is disconcerting. The first time the sustainer backslid before igniting and the second stage wound up going near horizontal. Second launch was better.
Good luck.

 

[Antares JS]

Hopefully third time's the charm. I'm planning to fly the Doubles again at the MDRA launch this weekend and try GlenP's suggestion of scraping the inside of the sustainer motor a bit.

 

[kitbasher99]

Please let us know how it goes. We here at Semroc have an Omega kit we would like to release but we can't get the sustainer to light either. Makes it hard to sell if it won't work right.

 

[kuririn]

Maybe a static test with just the motors taped together and clamped?
Easy to set up and no chance of damaging the rocket.
See if the NE motor lights the sustainer.
If not, maybe defective motor batch?

 

[Ulexis]

Please let us know how it goes. We here at Semroc have an Omega kit we would like to release but we can't get the sustainer to light either. Makes it hard to sell if it won't work right.

Dang, I need that Omega.

 

[Antares JS]

No joy, failed again. On a related note, Doubles has now survived three lawn darts into wet sod. That has to be some kind of record.

I guess it's possible I have a defective batch of NE motors, but the sustainer motors come from a 24-pack of regular MMX II motors that have had many other successful flights.
actual booster motor would be sending burning BP forward.

I think I'm going to take Kuririn's suggestion of doing a static test to try a few more drastic ideas before trying it in the actual rocket. My first idea is to sprinkle a TINY pinch of BP (like, a few grains) down into the forward end of the booster. My best guess is that the delay is not moving enough hot gas forward to start the sustainer. Since an actual booster motor would be sending burning BP forward, I'm hoping this might help.

 

[kuririn]

AntaresJS,
Revisiting this thread, after thinking about it it seems more than coincidence that both you and kitbasher are having problems with the NE motor.
My batch was purchased a few years ago. Perhaps there is some small difference between my batch and the newer NE batches? Would you like to try a few NE motors from my batch and see if that makes a difference?
No charge, I have plenty.
EDIT: I just remembered, shipping rocket motors requires special regulations. Will have to check with the PO about these smaller motors. Don't know if they can go by air.

 

[Antares JS]

AntaresJS,
Revisiting this thread, after thinking about it it seems more than coincidence that both you and kitbasher are having problems with the NE motor.
My batch was purchased a few years ago. Perhaps there is some small difference between my batch and the newer NE batches? Would you like to try a few NE motors from my batch and see if that makes a difference?
No charge, I have plenty.
EDIT: I just remembered, shipping rocket motors requires special regulations. Will have to check with the PO about these smaller motors. Don't know if they can go by air.

If you're able to ship them, I'm interested. Keep me posted if you're able to find out.

 

[kuririn]

After doing some research it appears the shipper must obtain a Letter of Authorization from the USPS Manager of Mail Preparations and Standards in Washington DC, 30 - 60 days for approval.
Then even MMX motors must be shipped by surface mail, air shipment not allowed which means a slow boat from Hawaii to the West Coast.
Not worth it in my opinion.
I will, however do a static test and report here in a few days.

 

[Antares JS]

Agreed, not worth it. Thanks for offering though. Keep us apprised of your tests.