Why Not Cluster AT FirstFire's?

I think you should test the idea outside of motors a few times. Will the FirstFires ignite at the same time every time? Testing the concept with motors in a rocket is not the best idea.

Larry,

If you're going to use 50 caliber Pyrodex pellets at the top of your motors, all you need for ignition is a single e-match. The Pyrodex will not only ignite the propellant, but will pressurize the motor, and lift off will be quick. Works well.

James

That should read a "single e-match for each motor."

J

The problem with FirstFires is that they require a lot of juice to get them to fire, compared to a regular e-match. That's also why they can't be used for airstarts -- most electronics don't put out enough power to fire them quickly and reliably.

You could probably cluster them for ignition on the pad IF you will be using a powerful launch system. The only way to be sure it will work, and work reliably, is by testing them with the system you'll be using. Use as many igniters as you intend to use in the rocket. No motors, just the igniters. If they all light, at the same time, you should be ok.

=B7

I would use them to launch off the pad. I don't remember seeing any numbers but do they draw significantly more current than other igniters such as Firestar, Magnalight, etc? I have clustered 3 of those and they all lit OK in the past. I have had a few not light the motor and that's not good :( in a cluster. That's why I thought about using a Triple7 pellet with them.

Of course I would use an e-match if possible but the ATFE.... Since FF's are still included with 38 mm AT reloads I am looking for a way to use them. I didn't renew my LEUP when it expired a while ago because I had no permanent job or residence, but it looks like we'll be in Phoenix for a time so I'll do the paperwork and try to get one again (in the meantime I'll sure miss 54 mm motors). Larry Lobdell Jr.

I would use them to launch off the pad. I don't remember seeing any numbers but do they draw significantly more current than other igniters such as Firestar, Magnalight, etc? I have clustered 3 of those and they all lit OK in the past. I have had a few not light the motor and that's not good :( in a cluster. That's why I thought about using a Triple7 pellet with them.

Of course I would use an e-match if possible but the ATFE.... Since FF's are still included with 38 mm AT reloads I am looking for a way to use them. I didn't renew my LEUP when it expired a while ago because I had no permanent job or residence, but it looks like we'll be in Phoenix for a time so I'll do the paperwork and try to get one again (in the meantime I'll sure miss 54 mm motors). Larry Lobdell Jr.

Zero, nada, zip chance of getting storage within the city of Phoenix. The local fire marshal won't allow it. I know of one approved storage in the area, and it's on "county land", and not part of any town or city. Talk to the "Hillbillies".

Also, ask BBBBBBBB about clustering "first Fires" in the BDR! (what an interesting flight it was!)

You mean what a mess to clean up! Still have the nose cone frome that day!

7.5" Loc under my house as a reminder to not let the money guy install the igniters. He is only allowed to push the button!

Clustering First fires BAD IDEA!!!! Easy to do but a BAD IDEA!!!! Even with MASSIVE current they will fail! But it's your rocket and I like to see see other people crash rockets! Just NOT ME!

BBBBBBB

Thanks for the reminder I live in Phoenix. I figured there was no chance of getting storage in the city so I had intended to ask around when I meet some HPR people here. Who are the "Hillbillies" (I remember the TV show Beverly Hillbillies), and what about FirstFires in the BDR? I'm ignorant so who is BBBBBBBB?

Larry

AZ Woody wrote:

Now I'm really curious. No flame wars - just curious. I don't like to see anyone's rockets crash. Why do they fail? Are they just bad igniters? Then why do they work as singles for me +80% of the time? Maybe the bridgewire is like a #10 nichrome or something so it takes a huge car battery just to heat one up? Looking for answers. Larry

Now I'm really curious. No flame wars - just curious. I don't like to see anyone's rockets crash. Why do they fail? Are they just bad igniters? Then why do they work as singles for me +80% of the time? Maybe the bridgewire is like a #10 nichrome or something so it takes a huge car battery just to heat one up? Looking for answers. Larry

Now I'm really curious. No flame wars - just curious. I don't like to see anyone's rockets crash. Why do they fail? Are they just bad igniters? Then why do they work as singles for me +80% of the time? Maybe the bridgewire is like a #10 nichrome or something so it takes a huge car battery just to heat one up? Looking for answers. Larry

"Hillbilly Rocketry" is the group that does (among other projects) the Gila Monster.

BBBBBBBB (various number of B's), is "Big Bad Bob". He lives up in Pinetop now (last I heard) but makes it down for some launches.

The "BDR" was one of SSS's first "club projects". (late 90's?) It was a tube fin bird that was built for a cluster of 2 38mm, with no electronics.. (the "Big Dumb Rocket"). It was flown many times, and BBBBBBB and I were there during that time.

If you've not hooked up with SSS or Ahpra since coming to Phoenix, you really need to. (they both fly at the same site, but on different weekends)

See sssrocketry.org and ahpra.org. Head out to the SSS launch (GHS Memorial) at the end of October, and you WILL meet some of the HPR folks...

(former TRA Prefect for SSS, and still TRA L3 here! I'm in Ahwakutee)

Thanks for the info. I think I remember seeing the Gila Monster on Discovery TV - Rocket Challenge. I plan on taking my 2-stage to the GHS SSS launch next month. But if I read the web right you need your own launch equipment. I used the club stuff back in MI so I don't have a pad like I will need for this rocket (4" x 10' & ~20#, rail buttons for 1-1/2" rail). I wrote to James Brill and he forwarded it to the SSS group mail but I haven't heard from anyone yet. The 1st stage has a 54mm main mount with 2 38mm permanent strap-ons, and the sustainer has a 54mm mount. For the first launch I intend to use 2 I357T & an I435T staged to a I212SS. If that goes ok I want to try a J540R with 2 I435T air-starts staged to a J180T. I also have a LOC EZI-65 that I could bring.

Where is Ahwakutee? Larry

I still have no idea why the multiple posts of the same thing. Sorry. Larry

Hey Larry,

Miss having you around back here in Michigan!

The First Fires are awfully expensive ($9 for three last I saw), and not nearly as reliable as a dipped ematch (Oxral). I have heard that some of the M-Tek matches "pop" a little too hard and will blow pyrogen clean off with no ignition.

I have lit a number of clusters with Oxrals dipped in Igniterman pyrogen. These flights include both Hybrid and solid motors. The largest cluster was

7 J570s. Pad cam footage indicated they were all lit very close together (within the 1st foot of movement and the thrust to weight was about 60 to 1).

Knowing that Oxrals are no longer widely available and that M-tek has not yet released their slower match (which is coming) I would recomend using copper Thermite (also known as Magic Pixie Dust). This can be fired by any ematch and ignition is almost instantaneous!

Hope this helps

Mark Palmer

Ditto here! The Fire-in-the-hole igniters have never failed once when it comes to clustering composite motors. Although, I should mention that composite clusters for me at least has been 24/29mm motors.

Bottom line, I've never witnessed, or heard, of First Fire igniters used in a successful cluster.

Ted Novak TRA#5512 IEAS#75

I'm getting ready to cluster 7 SU Aerotech motors (6 F42Ts and 1 G40W) using self-dipped Magnelite igniters. Any suggestions? I have a box of 50 e-matches that I keep for staging and DD which I'd rather not try to use on this launch. I'll be using a strong 12V deep cycle marine battery connected to a relay.

-Aaron