Oh great lords of the sky..... Going to try to launch my first ever Cluster of 3 29mm H151 CSI engines at MHM.... Only ever clusters Low power before..
Any suggestions on how I can help make sure they all light? I heard/read dipping the igniters in Pyrogen might help... don't personally have any and don't know where to get it, but willing to spend money to protect the investment... What is the best advice out there...?
Kevin.
Great choice on using CTI H151-15A. Cti has a black powder pellet that starts the ignition process after the ignitor. Probably will not need anything else. At least I am pretty sure the 29mm do. The ignitors supplied come pre-dipped.
Use the full length of the supplied ignitors. Secure them to the launch pad. BUT allow for some upward movement. The rockets upward movement pulls the ignitors out. This gives each ignitor all the burn time it has.
I have had them pull out two when only one motor has lit. Giving the extra slack allows for one motor being slower then the other(s).
Test each ignitor for continuity before installing.
You will not need all three ejection charges. Empty two. And be sure to change the delay to desired time. They have a 15sec out of the box.
Pyrogen: I have always used Quik-Dip from QuickBurst works great. http://www.quickburst.net/quick_dip.htm
I would bet Cool Rocket Stuff or Giant Leap will have some on site. I will have mine ready to dip for your use. There are other brands also.
I have made some from ping pong balls (recipe on internet search) but I prefer taking me out of the equation and use the best. It worked great but always had a small doubt in the back of my brain. Other more advanced people in the club would have other recipes.
Please lets hear of your rocket. I'm very anxious.
I will be in a 2004 White Chevy Van from Wyoming. If you need to dip.
Thanks Mike! I might take you up on that unless I can pick some up from the new moto-joe crew...
Simple design as I have never HPR Clustered before. Blue tube, 3 29mm engines in a cluster. I did get fancy and ordered some of those metallic looking fins, Thinking about painting it to look like its all metal. Will stop by..... Took tomorrow off to finsih the gluing...
correction to my post. CTI come with e-matchs. Not dipped. But I have never dipped them.
Most has already been covered above. I wouldn't bother with any additional pyrogen dip for CTI motors. I've lit clusters of them on the ground and in the air (3 38mm CTI's started with a Perfectflite minitimer and 9V battery) with no issues.
On the pad, borrow a second pad and set it right next to yours. Run the ignition wires up the additional pad, tape in place, then loop down to clip onto your igniter set (in parallel, obviously). This will give the rocket another 10 feet or so to be sure they're all lit. Also, tell the LCO to hold the button down!
There are plenty of regulars at the launches who are very familiar with clusters and will help you out. I'm no longer a regular, but chime in online frequently.
-Ken
Thanks Ken. I think I am picturing what you are saying. Basically make it so the pull on the ignition wires doesn't significantly happen until it is much higher on the rail.
Exactly.
With e-matches and Cesaroni motors, you are better off putting the ignitors in series, rather than parrallel. At least, that's how I have always had the clusters in my falcon light. E-matches are typically used in the pyrotechnics business and are almost always run in series to get all of the devices to light. Doing so in a parralle conffiguration generally requiresextra juice to get them all to light.
n series wiring, there is one single loop for the electricity to flow from the red terminal of the Firing Module cue, through all e-matches or igniters, and back to the black terminal. Each e-match receives the full current. The amount of current that flows through them all is a function of the output of the Firing Module and the amount of resistance of the combined wire and e-matches in the loop.
In parallel wiring, there are multiple paths for the electricity. Each e-match receives only a fraction of the full current.
David P. told me this on Thursday and really I didn't think about it as low power I always did parallel. Is this due to the fact that an e-match doesn't actually burn through so the connection to the others is not necessarily broken when one burns? Interesting...... Glad you guys passed this along, i would have done it wrong... Thanks!
I've always been concerned that the starter (ematch, igniter, or whatever) would open upon firing, like every Estes igniter I've used, so parallel is what I will continue to use.
As an EE, I have to question whoever wrote up the description that MikeS pasted in. That would only be the case if one had a Constant Current source to fire the matches. We use car batteries, which are a (relatively) constant voltage.
Example:
12 volt battery, 1 ohm ematches, 3 in parallel: each ematch has 12V across it, thus I=V/R=12/1=12Amps each
12 volt battery, 1 ohm ematches, 3 in series: voltage is across 3 ohms, so I=12/3=4Amps.
With standard igniters, more amps = go. Ematches don't take much of either volts or amps, so a non-issue. If ematches go short upon burning, series would be just fine, as Joe stated that's how he and the pyro crowd do it.
I'm still 100% on cluster ignitions (as long as you exclude that launch that I didn't arm my timer!), so I'll keep doing what I'm doing until it no workie no more.
-Ken