modifing ignighters

HI,
I am doing a cluster of a J350 and two H128's. The rocket is too heavy
to be lifted by just the J350 or the two H128's, so I want to get all
the motors lit on the ground.
A few other people on rec.models.rockets had given me some very helpful
information on ignigting clusters, and wanted to modify one of them.
I wanted to know if it is possible, and safe if I used two davey fire
matches in the J350 that are each double folded, and with the match
heads touching,I dip them in pyrogen? The two smaller motors would then
just have a single dip of pyrogen. I thought that this would ignight
the motors very quickly since the H's do not take long to come up to
pressure.
Thanks a lot,
Tom Sak
Reply to
TJ
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Tom,
Just a word of advice and caution because I have seen this happen. I personally would NEVER launch a rocket that could not be lifted to a safe altitude by just the central motor. I have seen what you want to do attempted before. Not all the motors ignited as planned. The rocket gained 50 feet in altitude, went hortontal, then another motor ignited, took off like a cruise missle, and almost caused a major accident.
Les Kramer
Reply to
Les Kramer
That is what the Missileworks remote is for.
To the original poster:
Do you have access to a Gwiz? If so, set it in cluster mode, then use the Gwiz to ignite the outboards. Of course, my personal preference for such a launch is an I457, then use the Gwiz to airstart the WL outboards.
Reply to
Tweak
You could get an I600R in that 38/720 case now, which would probably solve the worries :-)
BTW did you mean I357T or I435T ? I435T would be a good choice too, its peak thrust is ~800N at ignition, and stays above 500N for the first 0.6s of the burn. Then again the J350 has quite a hefty peak too. How much does this rocket weigh?
In the first 0.5 second the H128's will give you ~180N thrust each, and the J350 would kick in at ~900N, dropping to ~570N at 0.25s and ~500N at 0.5s, so overall in the first 0.5 second your thrust will be at least 860N. Are you working to 5:1 at that figure, or 5:1 based on 350+128+128, which gives you ~600N, in which case having only the J350 lit would give you similar numbers (based on the average thrusts). However, if only the H's light, I can see how that would be bad ('only' 360N to play with).
Hope my musings are of some help...
Reply to
Niall Oswald
Hi,
I hadn't checked back here in a while so I couldn't reply. The rocket weighs 18lbs fully loaded with a J350 and two H128's. I didnt realize that this was going to be a serious problem, but I can now see why.The largest motor I can use is a J420R, however I would then be clustering two propellant types which probably is not a good idea. If I had to, I could definitly fit a J570 in there, but its not in my budget right now to get a new casing. If anyone has any suggestions they would be greatly appreciated.
Thanks a lot
Tom Sak
Reply to
TJ
Try a Loki Research J528. 180 pounds of initial thrust will pick that rocket up, no problem. More total impulse than an AT J350 and lower price too. All Loki dealers will lend hardware until you decide to buy (and you will, 'cause you'll like it so much).
- Jeff Taylor Loki Research
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TJ wrote:
Reply to
Jeff Taylor
Hi Jeff,
That sound like a great idea. I tested one of your I405's in my patriot last year and had a great flight. I think Bob sells your motos at METRA so I think that what Ill do. I'm guessing that you cant cluster that motor with aerotech motors right?
Thanks for the advise,
Tom Sak
Reply to
TJ
Hi Tom -
Bobby at Hangar 11 will certainly have a set of hardware to loan or rent, I'm not sure what his policy is, you'll need to ask him.
There's no reason why you couldn't cluster with motors from another manufacturer. Just make sure that your cluster is symmetrical.
Good luck with the flight,
Jeff Taylor Loki Research
TJ wrote:
Reply to
Jeff Taylor

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