HPR Sustainer Ignition

[Marsman]

I’m new to high power staging and am looking to try it this summer. I’ve been reading thru all relevant TRF and Rocketry Planet threads to gather information and learn from other’s experiences, but there seems to be a lack of discussion about upper stage igniters.

My project is an L2 size rocket, about 10 ft tall fully stacked. The sustainer is 4" in diameter with a 38mm motor mount and weighs about 6lbs empty, and the booster is 4" with a 54mm motor mount and weighs ~2 lbs empty. The electronics are an RRC2 altimeter and a Perfectflite miniTimer. The expected motor combination is close to a full J in the booster and igniting a full I motor about a second after burnout, achieving about 5500 ft. I’m not going for altitude, just the joy of the project and pulling off something this complex.

As the upper stage motor will either be something like an Aerotech I284W or a CTI I540WT, both 38mm, I’m looking for some advice about the igniter to use. If I go with the CTI motor, am I able to use the standard Pro 38 igniter that comes with the reload with a 9v batter and a miniTimer? Or alternatively, if I use the Aerotech white lighting load, what would an adequate igniter be? I’m planning on using a standard 9v battery, but I’m open to changing that.

If possible, I’d like to test the ignition system on a lower scale G to F motor flight, but I’m not sure that the system used to ignite a 38mm I motor or 38mm baby J would be compatible with a mid power rocket flying with an F motor.

 

[JDcluster]

Mine weighed in at 18lbs on the pad with 4 motor in it ( 3 in the booster & one in the sustainer) https://www.users.nac.net/jdcluster/2stage.htm.

I've never tried a true timer for upper stage ignition. I would suggest a type of G switch set for burn out. You mention 1 timer & 1 altimeter; I'm guessing that one section will have motor deployment only? On the right combination the sustainer may be close to mach & could cause you Perfect flight problems.

I'm not sure if CTI provided igniters are low current or not do some ground testing to make sure they will light with the timer.

Make sure that your inter-stage connection is strong enough to endure the stresses of flight; double wall it if possible.


Good Luck

JD

 

[highpowerrocket]

A fresh 9v battery will be sufficient to ignite a low current e-match. I use a 9v battery to ignite the sustainer igniter e-match and a stage separation charge (e-match) simultaneously, in parallel.

The CTI motors use a low current e-match so you will not need to do anything special when using a CTI motor in the sustainer.

For an Aerotech motor you will need to use a low current e-match but since the Aerotech motor does not have a pyrodex pellet in it (like the CTI motors) you will need to dip the e-match in pyrogen (or use some other ignition aid such as thermolite).

I suggest a fast burning, high initial thrust motor (like Aerotech Blue Thunder) for the booster. Your "close to a full J" in the booster would suggest something like an Aerotech I435T.

I have a Nike-Black Brant that is very close to what you describe for your rocket, except my rocket weighs in at 10 lb empty. With an Aerotech I-435T boosting to an Aerotech I284W the maximum velocity is only 600 ft/sec. With the motors you describe I do not think you need to worry about going supersonic.

BTW - I use a standard standard PML coupler for the interstage and I have never had a problem in several dozen two and three-stage launches. On occasion one will become chipped or cracked so I only tack them in place on the booster side so they can be replaced easily.

For more info check out the multi-stage stuff at :https://home.roadrunner.com/~highpowerrocket/

 

[dixontj93060]

Nice website!

https://home.roadrunner.com/~highpowerrocket/

 

[cjl]

Initially, I'd go Pro38 on top. Make sure you use a load with the ignition pellet (the vast majority have the pellet, but a few do not). They light quickly and reliably, with low current requirements.

 

[bobkrech]

..,For an Aerotech motor you will need to use a low current e-match but since the Aerotech motor does not have a pyrodex pellet in it (like the CTI motors) you will need to dip the e-match in pyrogen (or use some other ignition aid such as thermolite)...

For more info check out the multi-stage stuff at :https://home.roadrunner.com/~highpowerrocket/

Nice website.

BTW -The Pro38 built-in ignition pellets are BP, not Pyrodex(R).

Initially, I'd go Pro38 on top. Make sure you use a load with the ignition pellet (the vast majority have the pellet, but a few do not). They light quickly and reliably, with low current requirements.

I'm pretty sure the Pro24 thru Pro54 motor lines all use a built-in starter BP pellet. Which loads don't?

Bob

 

[JDcluster]

Not all of the Pro XX motors have that pellet.
I have a G 185 that has no pellet & I'm pretty sure that the H 400 that I flew last year didn't either.




JD

Nice website.

BTW -The Pro38 built-in ignition pellets are BP, not Pyrodex(R).


I'm pretty sure the Pro24 thru Pro54 motor lines all use a built-in starter BP pellet. Which loads don't?

Bob

 

[cjl]

Nice website.

BTW -The Pro38 built-in ignition pellets are BP, not Pyrodex(R).


I'm pretty sure the Pro24 thru Pro54 motor lines all use a built-in starter BP pellet. Which loads don't?

Bob

Primarily some of the ones with larger cores. This includes several Vmax loads and the J530 Imax, among others.

 

[brianc]

Noticed on RP, that Ray Dunnakin's Staging HPRpublication is available
again (now from ARAPress).