Mixing composites and BP motors in clusters

[ScrapDaddy]

Say I had a rocket that used a E6 composite in the core and a D12 in each o the fall away boosters, if I were to use a Q2G2 for the composite, would the difference in ignition time be bad enough to core sample the core? The D12 would almost certanly be doing all the lifting durning the first few seconds of the flight.

 

[ben_ullman]

I would make darn sure the E6 was primed well.

Composite motors light a little bit slower than Bp. What I would do is add some lead wire to the Q2 ignitors. Making them about 12-18" long total. And tape them to the rocket GOOD (dont skimp on the tape) that way when the first ignitor lights and starts propelling it the others arent ripped out of the rocket when it starts moving. The trailing wires arent going to hurt the rocket in any way. This is what I did with 3 foot Ematches when flying my 29mm Deuce. I would then have a burnt chunk of wire apon recovery. But I never had a motor ignition failure using this method.

Ben

 

[Luv2launch]

Rocketflite MF ematches, after watching Delta22 mix composites and BP motors using these ematches it would be the only way I would try do mix the two kinds of motors.
Here is a launch with clustered G71's and D11p's
https://www.rocketryforumarchive.com/showthread.php?t=42692&highlight=toginator&page=8

Scroll down the page a bit for the luanch photos and I believe a video.

 

[cjl]

Luckily for you, the E6 is blue thunder propellant. It lights fairly reliably, and as AP motors go, it lights about as quickly as can reasonably be expected.

That having been said, it won't light as fast as the D12s. Make absolutely sure you have plenty of power in your ignition system, and make sure the E6 igniter is solidly attached to the motor so it won't be pulled out at first movement.

 

[ScrapDaddy]

Well look like I have a couple things in my favor, would a fullboost controler cut it? Or would I have to use club equipment?

 

[ben_ullman]

Well look like I have a couple things in my favor, would a fullboost controler cut it? Or would I have to use club equipment?

how many amps does this fullboost thing put out?

Ben

 

[ScrapDaddy]

It uses 8XAA batteries so about..... One sec about 2.4 amps per battery so about 20 amps total at 12V

 

[Luv2launch]

To reliably light a cluster you would need a real 12 volt launch system with a realy at the pad and a good 12 volt motorcycle battery or gel cell double A batterys won't be reliable enough to do it.

 

[cjl]

It uses 8XAA batteries so about..... One sec about 2.4 amps per battery so about 20 amps total at 12V

It probably uses the AA batteries in series, not in parallel (actually, it definitely uses them in series - it's the only way to get 12v from AAs), so you can't just add the current like that. You're actually looking at 2.4A at 12V.

That's not enough. You'd want a launch controller using a 12V gel cell or similar, ideally with the battery at the pad along with a relay.