The instructions for the first fires specify 12 volts, 3 amps but don't
really provide that much other info
http://www.aerotech-rocketry.com/customersite/resource_library/Instructions/Misc_Instructions/how_to_use_firstfire_ign.pdf
I suspect output latch time could be a contributing factor as well.
Greg-I think this is possibly the first time I've heard of someone having
an issue with a Stratologger that wasn't normal user error. It seems that
the brownout protection should prevent this.
-Andrew
On Fri, May 25, 2018 at 1:55 PM, Richard Dierking <applerocketry@xxxxxxxxx>
wrote:
I have some questions about all this. First, Terry and Greg L, I thought
you guys had good jobs; why are you buying crummy igniters on eBay? Should
we all chip in and get you some good igniters? :-)
I know, I know, it’s fun to try new stuff.
To the main question, where did the information about FirstFire's needing
12 volts start? Specifically, First-Fire or First-Fire Jr?
The reason is, I don’t believe it, and want to test this. But, before I
do any testing, I want to assure we agree on the question. How about, will
a Raven 3 light a First-Fire Jr. or First-Fire igniter on the air-start
channel using a 9 volt battery?
Richard Dierking
The Skeptical Rocketeer
On May 25, 2018, at 10:45 AM, Chris J Kobel <chris.j.kobel@xxxxxxxx>
wrote:
Terry,
Sounds like a plan…great research and discussion. Just to reinforce what
Mike and others have said, make sure whatever ignitor combination you come
up with stays at the top end of your motor. I was using Pyrodex pellets
for a while, just cramming them (or pieces) into the core of the top
grain. What I noticed is that when they started to burn, they shrank in
diameter and fell to the bottom of the core, leading to an embarrassing
series of chuff-chuff-starts (and consequential early ejections!). I am
also a fan of taping the igniter and enhancement to a thin dowel to hold it
in place near the top of the motor. The red Aerotech caps are useful for
holding these dowel/igniters in place.
Looking forward to seeing this rocket fly at RocStock. And no Mike, it’s
NOT too early to start having RocStock fever! 😊 (ask me how I know!)
Chris
*From:* roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-
chat-bounce@xxxxxxxxxxxxx <roc-chat-bounce@xxxxxxxxxxxxx>] *On Behalf Of
*Terry
McKiernan
*Sent:* Thursday, May 24, 2018 10:37 PM
*To:* roc-chat@xxxxxxxxxxxxx
*Subject:* [roc-chat] Re: choice of igniters / ematches for airstart of H
or I class motor
Thanks everyone for all the suggestions on igniters. I'm glad I asked.
Originally when I had planned to use the PET2+ for airstarts, I was just
going to have some 9V batteries since that's what the PET2+ instructions
suggested. It was my son actually who noticed the Aerotech voltage
requirement in a forum posting and brought it to my attention, leading to
this email thread. I'm glad he noticed and I didn't come out to ROCstock
with a combination that would never have worked!
I decided to go with the ClusterFire pyrogen dip kit and a bunch of
chipboards to make ematches. Seemed like a good investment compared to
buying pre-made igniters at a couple dollars each. I'll save the Aerotech
igniters that come with the motors as backups for future ground-based
launches. Maybe I'll dab a little Pyrogen on the sustainer motor grain.
Also, Kurt G. offered to give me a Pyrodex pellet to put up in the
sustainer to help ensure ignition.
For the Raven battery power I'm going to use a 9V for the electronics --
that's what they recommend in the manual to avoid damage from overcurrent,
and I already have a 9V mount in my e-bay. You can use a 1S LiPo for the
electronics instead, but even then you have to be careful to get one under
170 mAh. LiPos are certainly nice and light but since I already have ten
pounds of rocket, saving a few grams on the battery didn't seem worthwhile.
For the pyro charges I will be using some CrazePony 400 mAh 2S 30C LiPos,
both for the motor ignition off the Raven and for the backup ejection
charges on my EggTimer. They were the right combination of size, capacity,
current etc. -- small enough to fit in my crowded e-bay, plenty of juice to
run the EggTimer GPS / finder for hours if necessary, enough voltage &
current to light the ClusterFire igniters. There will be 3 of them -- 2 on
the EggTimer and 1 on the Raven. So, I've got redundant everything on the
electronics.
https://smile.amazon.com/gp/product/B072BH1XP6/ref=oh_aui_
detailpage_o02_s04?ie=UTF8&psc=1
BTW last year I bought some fireworks starters on eBay, similar these:
https://www.ebay.com/itm/100pcs-50cm-Length-fireworks-
firing-system-copper-wire-E-matches-Safety-igniter/273196526167
I tried one out with a 9V an it made quite a pop. I expect these would
light an ejection charge without any problem, though I have my doubts about
lighting a motor. They were certainly cheap compared to buying e-matches
from rocketry vendors. Anyone ever tried these for use with rockets? I'm
not planning on using them at ROCstock since I have the ClusterFire kit
coming and that seems more likely to work, but I'm just curious if anyone
has gone the fireworks starter route.
Thanks again everyone
Terry
On 5/24/2018 4:12 PM, Paul Pittenger wrote:
Two advice points.
1. MJG new blue wire ematches dipped in pyrogen. I use magnalite. If
enough room in motor core I fold over the top this reduces any tendency of
ematch to slide down the motor core during the liftoff Gs or to spit itself
out the aft end of motor upon ignition.
2. Test on the ground use your chosen ematch and pyrogen to launch motors
from the ground. During my testing I had a chance at one launch to run my
own wires out to the pad. For testing pyrogen dips I was launching 29mm and
38mm motors using a AA battery. That made me really confident my airstarts
would work with LIPO or 9V battery
Just my opinions - have fun experimenting!!!
Paul
Sent from my iPhone
On May 24, 2018, at 2:44 PM, Mike Riss (Redacted sender "rockt_dude" for
DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
My suggestions are to first start with your electronics. Since you're
using a Raven, contact Featherweight to see what they recommend. Adrian is
pretty good about providing advice, and has a lot of experience.
Also check out the online forums and look to see what other Raven users
have had success with.
The MJG and similar initiators aren't intended for starting composite
motors by themselves. They can be used when augmented, either with a
pyrogen dip or some other energetic material like a pyrodex pellet or a
small piece of easy to light propellant. Their main advantage is the low
current required to ignite them, but the disadvantage is that by themselves
they don't generate enough energy to get a motor started.
Slim Gem and similar initiators like those provided with Aerotech motors
are generally intended for use with ground-based 12 volt launch systems.
It's not so much the voltage but the current that they need to get going.
And as I mentioned in a previous thread, remember to take into account the
mass of whatever you do use for an initiator, and make sure it stays up at
the top of the motor.
Mike
P.S. Is it too early for ROCStock fever to be setting in?
On Wednesday, May 23, 2018 10:16 PM, Terry McKiernan <terry@xxxxxxxxxxxxx>
wrote:
Hello all,
Still trying to get my 2-stage high-power rocket project ready for the
June launch. I have a question about igniters I hope you can all help
me with. Basically I am looking for a recommendation: should I use the
igniter that comes with the motor, or buy an igniter more suitable for
airstarts, if there is such a thing?
My design uses two 3" rockets which are outfitted with Aerotech motor
retainers, and I have Aerotech casings, so I've only used Aerotech
motors with them. These are 38mm motor mounts and I'll be using class H
or I motors for the sustainer stage.
I am concerned that the Aerotech motors will be hard to start with a
small battery that can fit in a payload bay. I found a few posting
online indicating that Aerotech's igniters require 12V and can pull 15A+
momentarily when they short & burn. This is OK I guess for a ground
control system with a big fat car battery or marine battery attached.
But, it seems like an awful lot for an altimeter battery.
The airstart will be controlled an a Raven altimeter, and it does
support having a small 1S LiPo for the altimeter and a second battery up
to 20V for the pyro channel. And, yes, I can get a 2S 30C 12V LiPo on
Amazon. So, theoretically it should be able to start the motor using
the Aerotech igniter.
Alternatively I could buy some other igniter, or ematch, or make my
own. Any recommendations?
I am tempted by this ClusterFire kit, which promises 1 second burn at
5400F, using 6V and 2.3A:
https://www.rocketflite.com/store/index.php?route=product/category&path=61
Or maybe H-3 Compound?
https://www.apogeerockets.com/Rocket-Motors/Motor-Starters/H3-Igniter-Dip
Or MJG?
https://electricmatch.com/pyrotechnics/see/6/5/mjg-firewire-initiator
Note that at the March launch my Aerotech igniter on one launch failed,
and I tried an MJG ematch I had bought frombuyrocketmotors.com as a
replacement and it failed, and then I bought a FirstFire and it worked.
But, that was a ground launch not an airstart. In any case my only
experience with MJG was not good.
Or Slim Gem?
https://www.apogeerockets.com/Rocket_Motors/Motor_Starters/
Slim_Gem_Starters
One thing i note about Slim Gem is they also require 12V just like
Aerotech. Also according to the Apogee site they burn at 1400F, vs. the
5400F claimed for ClusterFire. Quite a difference...
Or Quest Q2G2?
http://www.buyrocketmotors.com/quest-q2g2-3-initiators-6-pack/
Or ... probably lots of other choices out there?
Thanks for any suggestions!
Terry McKiernan
--
ROC-Chat mailing list
roc-chat@xxxxxxxxxxxxx
//www.freelists.org/list/roc-chat
