more igniter questions

Quickbursts are good, but I disagree. A high energy discharge unit should be used for any cluster with three or more motors. Lots of people don't use them and still have success, but you will have much better ignition when using a discharge coil. Do you really want to bet on all of the hand dipped igniters having the EXACT same resistance, or the club launch system having enough amps to fire all of them simultaneously? With a discharge unit, they will all fire at the same time.

Coupled with thermite igniters, your project will leap off the pad. :)

Mike Fisher Binder Design

Any more info on this type of launcher circuitry?

I am not familiar with the discharge coil design.

Is there a link to schematics or a project?

TIA

What do you disagree with?

That "you don't need a backup" ie high energy discharge unit. For clusters, the more amps the better, no matter what igniter you use.

Mike Fisher

Yup.

Try Greg Deputy's rocket site at

Mike Fisher

Mike, what can I expect to pay for these parts? Also, I can see the two leads to the battery and the two to the igniters, but what hooks up to the brass screw? is that where I would connect the + side of my igniter lead that comes out of my relay? If so, to what to I attach the negative lead? Is there danger of power flowing back into my relay unit and frying it?

Thanks, Mike. I misinterpreted what you were saying about a "discharge coil". I already had the schematics for the Magneblaster.

My launcher uses a motorcycle battery and does not have a relay. I built it to launch my B cluster altitude rocket and it fires 5 Solar igniters without a problem (so far!).

But I'm always on the lookout for new and better ideas.

I must admit what you say doesn't make sense. A backup is a high energy discharge unit? To me a backup would be another igniter.

Barney

Fine, as long as you don't hold the clips and discharge it. Same as you wouldn't light a rocket motor while holding the motor in your hand.

If you cannot grasp the logic there, it's not safe for you. :)

Mike F.

Read the entire thread please.

Mike F.

I read the entire thread, and I agree that what you said doesn't make any sense. What does "backup" have to do with "high energy discharge unit"? Are you using a non-standard meaning for some of the terms? Backup in my mind means an alternative in case the primary fails.

I looked at the site, and it looks as though he is using a coil as a current store. A good-sized lead acid battery can deliver hundreds of amps as well. What is special about the coil?

Just trying to learn...

-- David

Sure, but I'd hate to be holding onto the clips when someone pushes the wrong launch button, or when there's a faulty relay or something. I've seen things like that happen with regular launch systems, but then you're only dealing with

The "high energy discharge unit" in question is no more than a simple relay. A relay with a high current rating to be sure but nothing more. There is no energy stored anywhere other than in the battery.

The actual current delivered depends on the total circuit resistance. So it may deliver more or less than 200 amps.

As for the other comment in the thread that more current is always better, that is nor strictly correct. It is possible to vaporize the bridgewire of an ignitor so quickly that it simply blows the pyrogen off of it without igniting it. But a

David wrote:

What site is that? The only site I saw listed in this thread featured a

Dave

Inductive storage???

Reece brought up the term "backup" to describe using his own dipped igniters and the Magnablaster in case the quickbursts wouldn't work for his cluster. I took that to mean his "backup plan", not a redundant system.

Another poster was quick to say that he wouldn't need the Magnablaster (backup plan) if he used quickbursts. While that may be true for a small cluster, he will probably need more amperage to get a reliable ignition if the cluster is three motors or more. Can it be done with just a good battery? Maybe, but why chance it?

A coil can store much more amperage than a straight battery can deliver, the same as a capacitor. The drawback is that they must have sufficient time to recharge after firing.

Mike F.