Interesting Falcon Heavy model.

[Grog6]

I have a large Falcon heavy model I'm going to do double deployment on, and I'm wanting to light the main AP engine first, and then light the BP boosters after the main comes up to pressure.
So I'm wondering if anyone has ever used the rocket plasma to trigger an ignition?
I'm thinking it shouldn't drop more than~80V, and it should be less, as burning plasma, I'd think.
Comments?

 

[boomtube-mk2]

Are you thinking about using some means to bounce the AP motors exhaust upwards and into the nozzles of the BP motors?
While that might be possible, I'm not sure any club would allow you to do it.

It seems to me that the only way you could perform the ignition sequence you desire is to have the BP motors wired to a separate set of wires controlled by a separate launch button, or different position on the launch controller selector switch.

 

[Scott_650]

I have a large Falcon heavy model I'm going to do double deployment on, and I'm wanting to light the main AP engine first, and then light the BP boosters after the main comes up to pressure.
So I'm wondering if anyone has ever used the rocket plasma to trigger an ignition?
I'm thinking it shouldn't drop more than~80V, and it should be less, as burning plasma, I'd think.
Comments?

Doing an air start of your BP motors shouldn’t be too difficult but that would mean using a flight computer with air start capabilities and running the wires to the booster motors - similar things have been done so you’re not in terra incognita here, just not done the way I think you’re describing it…I think an Altus Metrum Easy Mega or Easy Timer would work for air starting your boosters https://altusmetrum.org/

 

[teepot]

If your BP motors don't have enough thrust to lift the rocket alone then I don't see why you can't light them at the same time. I have a few rockets that have SRB's with BP motors and a AP motor for the core. If the core doesn't light they won't go anywhere. It is a little embarrassing to watch the SRB parachutes deploy while the rocket sits on the pad though. Kind of funny too.

 

[Grog6]

I'm going to build some electronics for this; the BP motors will start quickly, so I'm going to build a sensor to detect rocket exhaust before firing the boosters.Redirecting exhaust to directly ignite an engine would be too dangerous to attempt.
My AP motors are hard to light, and need pressure to burn, so they're finiky.

 

[jadebox]

Composite motors can produce exhaust well before they really ignite. Sometimes they chuff and other times the delay ignites before the motor. So, checking for exhaust may not be the best way.

I looked at lots of alternatives for a Saturn V I have been designing in my head for about 20 years and still haven't decided on the best method to ignite four outside motors after the central AP motor lights. Using an accelerometer to detect lift-off might cause too long of a delay before the outer motors light or a premature ignition if the main motor chuffs. If I used a break-wire, it also might trip early if the main motor chuffs.

I am sort of leaning towards just igniting all the motors at once as a standard cluster and using long-burning, low-thrust outside motors so the rocket won't fly unless the main motor lights.