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My gut feeling would be to go parallel. Although I have no emprical evidence to support this. Estes ignitors which use nichrome wire for example burn completely through thus breaking the circuit. Don’t know if this is a result of…   Read more»

Yes, and therin lies the problem. As you pointed out, the one will heat 1/2 as fast as the other two. The other two will light first, and break the circuit, and the one will never light. Also, if the…   Read more»

The problem is that when they are not all identical in series, they will not all heat evenly (the one with the most resistance will heat first). Then, when it goes, the circuit is open and none of the others…   Read more»

simultaneous ignition probably depends more on other factors than series v parallel such as the propellant type, igniter pyrogen type, placement, etc assuming one has a decent set up and batteriesI agree. One side aspect I wanted to do with…   Read more»

The problem is that when they are not all identical in series, they will not all heat evenly (the one with the most resistance will heat first). Then, when it goes, the circuit is open and none of the others…   Read more»

Doug,Sounds interesting as in real data vs opinion based on theory. Though the fact that some came up to pressure later than others really doesn’t tell us much given the variability in motor ignition to begin with. How many drag…   Read more»

I too had heard the auguments for using series e-matches and in fact I have tried doing it. For those of you who will be around Friday evening I have some close ups of motor ignition with the high speed…   Read more»

As an electrical engineer, I will strongly dispute the use of series igniters for the reasons that Chris gives. Unless there is a great deal more uniformity in the manufacture of igniters and ematches, the predictability of when an igniter…   Read more»

Chris,I am familiar with the arguments, and yours may be precisely why some with tons more experience than either of us recommend series wiring– somewhat slower but more uniform heating of the pyrogen?If I’m not mistaken Dave Bachelder is a…   Read more»

Parallel is ALWAYS the way to go, other than with some e-matches, and here’s why:First, in series, you are dropping the voltage that each igniter sees. If you have a 12V launch system, with 3 igniters, each only sees 4V….   Read more»

This is shaping up into a nice cooperative effort–gonna be a great cert flight. Now here is where we get into the serial ve parallel issue, as we want this to go off flawlessly. I used to believe parallel was…   Read more»

I can’t remember what I was looking for (other than some of the 18mm D’s), but email sent. Also, agreed that fuddruckers are nice – I was going to reccomend quickburst, but either will work great for those. As for…   Read more»

Here is my 2 cents, If you want to fly 3 H’s I have a case you can use. Also Joe, Dave Way, and I use Fuddrucker Igniters. I have a pile of them, they are super dependable. I have…   Read more»

I’ve got one H128 case, and Joe (cowan) has another. We need a third. I’ll be down there saturday early morning, and I’ll help after I get my big flight up. It would be nice if it worked though -…   Read more»

You guys are crackin me up. All I wanted to do is launch a big rocket and already I’m thinking about certification. I’ll go for the three wimpy H’s if you help me prep the vehicle being this is my…   Read more»

I checked the regs and as usual CJL is right about requiring that one motor be H or I–but clusters are allowed on NAR L1, L2 certs, not L3. Three wimpy H’s if we could come up with the cases…   Read more»

That’ll work, though it will go HIGH (4000 feet) on an H128I’d trust it before the 3 motor cluster though, and it’s not like it’ll drift out of the launch site 🙂

Thanks. I do have another I can cert on. It’s a LOC Precision kit – “Graduator”. The recommended motor is a G40-10. It’s 13 oz, 39.5″ and 2.63 in diameter. Don’t know if that will work or not with an…   Read more»

You can’t cert on weight alone. Strangely enough, there are designs that you must be certed to fly, but that you cannot cert on. This appears to be one of them (unless you wanted to go with an H128X3 cluster)….   Read more»

Correction on the CG/CP values. In the previous post the engines weren’t loaded. With the engines loaded the values are 39.7CP: 50.4kp