Most easily/reliably ignited composites for upper stage use?
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blackbrandt
That Darn College Student
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Blue loads. Also, pretty much any CTI load.
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I could be mistaken, but I don't think all CTI loads have the BP pellet.
I'm not sure on AT, but at a guess, in descending order of easy-light:
Blue
Black/Fast Jack
White
Red
Green
( I look forward to being corrected )
I'm not sure on AT, but at a guess, in descending order of easy-light:
Blue
Black/Fast Jack
White
Red
Green
( I look forward to being corrected )
First, I have ZERO experience with air starting motors, although that is on my next to build list
We had a flyer at BattlePark that routinely flew two stage rockets. He used his own EX motors. From talking with him and other posts here, my impression is that it the propellant doesn't matter as much as the ignition system. CTI are a favorite because of the BP pellet and ematch igniters. They use low current so air borne electronics have little problem lighting them. The Blue Thunder is an easy to light propellant and gets used for the same reason, easy to light with air borne igniters.
So I think it really comes down to having reliable igniters that your air borne electronics will fire, and pyrogen or propellant that will reliably light with those igniters. I know that sounds easy, but the devil is in the details...
Good luck and let me know how it goes. I'll copy anything that works well......
We had a flyer at BattlePark that routinely flew two stage rockets. He used his own EX motors. From talking with him and other posts here, my impression is that it the propellant doesn't matter as much as the ignition system. CTI are a favorite because of the BP pellet and ematch igniters. They use low current so air borne electronics have little problem lighting them. The Blue Thunder is an easy to light propellant and gets used for the same reason, easy to light with air borne igniters.
So I think it really comes down to having reliable igniters that your air borne electronics will fire, and pyrogen or propellant that will reliably light with those igniters. I know that sounds easy, but the devil is in the details...
Good luck and let me know how it goes. I'll copy anything that works well......
MClark
Well-Known Member
The propellants that are easily lit are typically not the most desirable for a second stage. Generally speaking Long burn formulas are more difficult to light than fast burn, Effect motor, colored flame, sparks etc, are harder to light.
If using a motor for a air start, (cluster, multi stage) I like to use the same motor, igniter, whatever supports the igniter under acceleration, in the configuration as it will be used, in a single stage ground launched rocket to test. Do multiple times if possible.
M
If using a motor for a air start, (cluster, multi stage) I like to use the same motor, igniter, whatever supports the igniter under acceleration, in the configuration as it will be used, in a single stage ground launched rocket to test. Do multiple times if possible.
M
CTI H123 skid mark air start with suppled e-match ignited with RRC3:
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That's so cool! Nobody missed seeing that one light! Smokey motors are good for the same reason... easy to see them when they light.
cavecentral
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I do not do air starts, but know several that do.
Same as on the ground - the igniter should fit through the nozzle. I do not believe air starting increases the chance of cato. The G of lift off can move the igniter towards the nozzle (or pull it out) causing failed ignition or poor ignition. Mainly an issue for large core motors or flimsy igniter wires (stranded wire or thin gauge). Some used head end ignition for this in larger motors. Other will have to fill you in on how that is down safely.
Also, need a low current igniter. Ematch with pellets, dipped ematch, dipped Q2G2s, etc.
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Any suggestions for the best way to support the igniter portion inside the motor to prevent setback due to Gs without raising the chance of a nozzle obstruction and CATO?
Head-End ignition....hold it from the top and nothing goes through the nozzle.
Head-End ignition....hold it from the top and nothing goes through the nozzle.
One trick that I have read about, but not tried (yet) is using the pyrogen dip for making your own ignitors to coat the inside of the grain of the upper stage/airstart motor, to help ensure ignition.
MClark
Well-Known Member
Head end ignition is best.
Many use a small wooden dowel to hold the igniter. Allows it to be easily inserted at the pad.
I like to put the igniter while assembling the motor, I glue a piece of nylon string to the forward insulator to hold the igniter in place. I use Aerotech and Ex motors. This is secure, no dowel parts to clog the nozzle but more time and work at the pad.
M
Many use a small wooden dowel to hold the igniter. Allows it to be easily inserted at the pad.
I like to put the igniter while assembling the motor, I glue a piece of nylon string to the forward insulator to hold the igniter in place. I use Aerotech and Ex motors. This is secure, no dowel parts to clog the nozzle but more time and work at the pad.
M
Salvage-1
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Hmmm.. Would superglueing the ignitor head to the top grain work?
MClark
Well-Known Member
Maybe. Glueing to propellant can be difficult, the outside layer of AP tends to pull off and the glue creates a inhibited spot.
Some motors the igniter can be trapped between the top grain and the forward closure or insulator.
On hard to start motors we used to use thermalite, the fuse, between the grains. It lights very easily and in the confinement of the grain gap burns very fast. But alas it is no longer available and only rolls of thermalite belong to hoarders. Like me.
M
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If you must fish a wire up the nozzle and don't mind installing the igniter early then just lay a toothpick across the top grain spanning the core and loop the igniter over the toothpick.
jrkennedy2
Well-Known Member
I believe for CTI, anything 75mm and larger does not use the starter "pellet". At least my 98mm,
Pro98 9876M1890-P doesn't... I could be mistaken.
ColumbiaNX01
Red blooded white American male
I think it is against the safety rules putting an igniter into the motor when your not loaded on the pad yet.
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There's some room in the rules for airstarts, obviously the igniter needs to be suitably inert... disconnected and/or shorted. Like any other flight, the RSO has the final say on this.
ColumbiaNX01
Red blooded white American male
Every launch I have been to including argoina you cannot have your igniter in the rocket until its on the pad. When I do my 2 stage the igniter will not go into the sustainer until the last final moment. anything can fail. Be the most prepared. I know when I RSO any rocket with a igniter in it will not pass until it is removed.
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That won't work for airstarts... the sustainer's igniter pretty much HAS to be installed before the rocket is on the pad, particularly if you're using a separation charge and shear pins to keep the stack together. If the igniter is disconnected from power and shorted, it's as safe as if it were not there... have you ever heard of an igniter firing spontaneously with no power?
ColumbiaNX01
Red blooded white American male
Well I said not at RSO. At the pad yea. It probably depends on the design of the rocket. If it is complex enough they may come to you camp and see how you are setting up and RSO it there.
You can install igniter at the pad.
Are you saying it is ok to have the 2 stage all together with igniter ready to go at RSO???? NO WAY!!!
Some launches might have more rules then others.
You can have the separation charges all hooked up just have to have the altimeter off. What I am saying is do not have the igniter even in the rocket. If the igniter is in the rocket hooked up to the altimeter at the sustainer and something happens it could be bad.
I have talked to the powers at be in argonia and if your doing a 2 stage they dont want the igniter in the sustainer motor until you get out to the pad and if that is when its on the pad or the last thing you do. There have been scenarios when the igniter has been in the sustainer and something happens and light the motor at different launches across the country. I dont know where I have just been made aware of the caution.
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Scoops
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I built a two stage rocket but haven't flown it yet. My plan was to follow the Public Missiles Thunder-n-Lightning manual for how to best keep the upper stage igniter at the top motor grain. You can download this from their website.
https://publicmissiles.com/secure/images/ThundernLightninginstructionbooklet.pdf
They recommend either:
A. (Preferred) Bend the end of the igniter with the pyrogen over 180 degrees (like an upside down J) then gently push it into the motor. It should have a friction fit. If the pyrogen breaks or cracks, don't use this igniter.
B. Bend a small kink in the igniter wire below the pyrogen then insert it into the motor. Again if the pyrogen breaks or cracks, don't use it.
Also, for both methods, bend a loop in the igniter leads and tape that to the motor's thrust ring/aft closure. I've heard of people using aluminum foil tape for this and they said it worked well.
Has anyone used either of these methods? Did it work ok?
jeff2space
Well-Known Member
So ok to have separation charge igniter hooked up to off altimeter but not ok to have motor igniter hooked up to off altimeter.
ColumbiaNX01
Red blooded white American male
If the motor goes off bad thing. Having the charges hooked up is one thing. When you arm your electronics on the pad whats worse ejection charge goes off or motor goes off????? If something goes wrong with the electronics your better off if the ejection charge goes rather then the motor. That is the risk we all run when we arm the electronics on the pad. The last thing you want to do is have the igniter go off because of a issue with the altimeter at the RSO or as your headed out to the pad. The last thing you do before you leave the pad is arm your arm your electronics that light the motor.
In my 2 stage situation I will set up everything at camp. Set up booster and sustainer independently. Head to RSO with no ignited in anything yet. Put booster on the pad at this point insert igniter in booster. Then begin to connect both the booster and sustainer. At this point install igniter into sustainer, dont hook it up yet at the motor. Slide sustainer onto rail. Connect the igniter. Button everything up. At this point start by turning on all electronics. The very last electronics to turn on is the one the ignites motor. Do this very last once your the only one left at the pad. In the event something happens like motor lighting on the pad your the only one in danger.
Another trick I learned is have a separate ematch connected to the staging electronics with everything off. It just hangs out behind sustainer. As long as it does not fire that means your staging electronics are properly functioning. Last thing you want to happen is there is an issue in the electronics that fire it off randomly because your moving the rocket around.
jeff2space
Well-Known Member
What are your thoughts about having sustainer motor igniter hooked to electronics but not inserted into motor? Just leaving hang outside the motor. Then follow your procedure but all you have to do before attaching sustainer to booster is insert igniter into motor?
I'm getting ready to build my first two-stage and trying to learn from everyone here and at my launches.
I'm getting ready to build my first two-stage and trying to learn from everyone here and at my launches.
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That's one way to do it and an accepted method at the club I launch at.
ColumbiaNX01
Red blooded white American male
That sounds good to me.
MClark
Well-Known Member
I believe the TRA rules say "at the pad", not "on the pad".
ColumbiaNX01
Red blooded white American male
Same thing. All I am saying is it has to happen out at the pad not at rso or camp. safety safety safety
It doesn't have to be on the pad, but all igniters for high power motors must either be installed at the pad or at a preparation area that is the appropriate safe distance from spectators. When installing the igniter and until the igniter has been removed or the rocket launched the rocket must remain pointed in a safe direction.
