Personally, I'd highly recommend the CTI motors for any cluster, staging, air-start application. I've had great reliability results with them with no fancy igniter prep. The Smokey Sam would provide a great accent for James' Red, but unfortunately no long burns. CTI has a "White" propellant that has about 2.5s burn in the H-J range, but I haven't' flown it.

On the wiring getting scorched, the trick I've used is to have the wiring conduits close enough to the motors so there's not much slack length of igniter wire hanging down. Install the igniter, push the wire up the conduit, pull snug, then screw down the connections. Screw terminals on the aft bulkhead might work also, but that's another connection to worry about.

For the multi-altimeter beeping issue, maybe wire up a headphone jack to each alt, in place of the beeper. Plug the headphones into each to confirm activity with no crosstalk.

Just throwing out ideas.
-Ken

Sorry I missed the meeting a week ago. Long story but ended up doing some time in local hospital due to "Bad Telemetry and a poor flight plan by the doctors". But, every mm of my airframe has been examined and cleared for flight, so I am good to go.

Did we find the missing Cess case? I think from the video I posted we should be able to print out a picture, grab a shovel and find it. A metal detector might help. I am hoping we are not in a fire ban on the 7th, but even if we are, I am willing to go look for it.

The missing 3rd stage motor was found the same day and so we are complete. Ken, I liked what you were saying about headphones but why not try my stethoscope and listen in that way as we rebuild it, then we could decide if we need headphones and headphone jacks. Maybe if necessary, depending on the electronics, we attach different noise making devices and alarms to the electronic devices so that they emit different pitches or frequencies than their norm if more than one uses the same sounds. I think that if we listen in with the stethoscope and have the boards more spread out through the air frame, we will be able to hear everything properly. Especially on the 2nd stage. Have them on 3 sides/locations, and maybe more vertical separation between devices, we will be able to hear more clearly. Just a thought.

I like the idea of having work going on at more than one location. I'd be grateful for the chance to participate.

I'll be watching for any announcements.

Ted Apke

I'll just throw my ideas out there - I hope to be more involved in the re-build if I have the time.

I've talked to James but wondered if there was a way to do a pull pin ignition of the outboards that would pass TRA & NAR safety code. This way as soon as the rocket moves less than 3" something would latch and light them. Less technology and less to worry about. Something like a relay or similar that latches an SCR. The less moving parts, the better.

As for the outboard motors, I agree that if you go commercial, CTI is the way to go for ease of ignition. Back in 2007 I worked with a group of high school seniors and they made 3 grain 38mm motors. We tested 7 motors before flight to validate their models and all used a 44/45 30 grain pyrodex pellet pressed into the top grain. Ignition was prompt when using an e-match threaded through the core of the pellet and into the grain. A plus is that the e-match lit the pellet, which stayed for a second and lit the motor. I've lit Pitch Black (ex version of a smokey sam) with it with no problems. Your cost for the motors is much less than commercial. If people wanted to, I could machine the 38mm cases very reasonably, material cost + 25%. You are looking at ~$30 for a 3 grain 38mm motor, closure and nozzle. And you get to use it after you fly the project. It could be a good introduction to research.

All in all, I was very impressed with the project and you guys did a great job!

Edward

Speaking of motor cases - I loaned a 75/6000 EX case to the group. Where is that case now? James? Steve? Someone else? I want it back or $100 for it. ASAP before it disappears into the back of someone's shop.

By the way, I'd prefer the $100 - I have no use for the case and would love someone who does to fly it.

Warren,

I have your 75 here in Longmont. I am home nearly everyday with this morning being the exception. You are welcomed to come by a grab it or, I will be heading by your place in the next week or two as I have visitors in who will be headed up to RMNP. No worries on it being lost or utilized, I have my hands full building a 4' PAC 3 with a 54 mount.

Ken, I liked what you were saying about headphones but why not try my stethoscope and listen in that way as we rebuild it, then we could decide if we need headphones and headphone jacks. Maybe if necessary, depending on the electronics, we attach different noise making devices and alarms to the electronic devices so that they emit different pitches or frequencies than their norm if more than one uses the same sounds. I think that if we listen in with the stethoscope and have the boards more spread out through the air frame, we will be able to hear everything properly. Especially on the 2nd stage. Have them on 3 sides/locations, and maybe more vertical separation between devices, we will be able to hear more clearly. Just a thought.

I like this idea. I think the stethescope would have worked if we had used it. I did make a last-second checklist for the avionics arming --but didn't use it because my hands were tied up hanging on the tower. Simple things like having one person on the ground with a clipboard, checking off items on a pre-rehearsed procedure, would have prevented a couple of my errors in the countdown activity.

The electronics in the second stage were the Raven and the Tiltometer. They have different enough beeps that they were easily distinguishable during the 2nd stage arming. The trouble was with arming the booster electronics at the end when all the other Ravens were beeping, and me forgetting to turn the cameras on the 2nd time around.

Adrian, I would be happy to work with you on developing procedures for location, arming, and testing; then committing it to a checklist that we could use together for the actual arming at launch. I am also thinking that we need holes in the lower bulkheads close to each motor so that we can stuff the ignition leads back into the fuselage and put a piece of aluminum foil tape over the hole. Then nothing is present to be scorched by the M's.

As for the lighting the outboard motors from the ground, that has its own potential problems, as has been demonstrated on a number of other failed or close-call big projects. When we go to smaller outboards to reduce the potential for offset thrust, if they were ground-started we would need to make sure that they wouldn't move the rocket in their own. The I115 that was mentioned has just enough peak thrust on their own to nudge the rocket off the rail while the central motors come up to pressure. If we do ground-start all together, we would need to choose motors that are really pretty wimpy, and they would spend a lot of their burn time with the rocket sitting on the rail.

The 3 Ms we used were barely enough to produce the 3 Gs necessary to trigger liftoff detection. With the 4th one to produce 33% more initial thrust, and lower overall weight with the smaller outboards, we would have better acceleration off the pad and quicker liftoff detection than we had this time. And now that we're aware of the wiring damage risk, we can protect the outboard wiring much better if we decide to continue with the concept of air-started outboards.

I have been working on a design to start events on rockets that is not a pull pin, (per the technical details) that could work on this project. It is bascially a spring loaded plunger switch. (Like a pressure switch) This switch has a rod, a spring, and some caps that act as limiters on it. I am thinking of brass tubing and a brass rod, but it could even be a maple dowel and an aluminum tube or even a large diameter plastic straw. The pin is in the bottom of the rocket or even in a separation of stages. By the pin being pushed up, where a spring on the other end is trying to push it down, it keeps contacts separated until the rocket moves a predetermined distance. When the rocket moves, the plunger starts closing the gap on contacts, being forced closed by the spring, until the contacts touch, forcefully, and the circuit is closed, thereby causing a new event to take place such as ignition of motors. This whole switch assembly has another switch, such as one of the Featherweight screw switches installed in line in the circuit, so that the plunger switched is never armed until the rocket is ready ot fly. I would be happy to build up a couple to show everyone to see if it would be acceptable. It could be made that the rocket has to move three feet before the circuit is closed. I have been reading the arguments in the TRA Forum and the plunger switch, IMHO, does not fall within the criteria for being a pull pin or any other device that has been eliminated from use in the discussion/rules. Any opinions or other comments?

WHOOHOO! Check out the ad in the last ROCKETRY Mag for Photo's by Nadine, she is advertising the 2013 calendar, looks like we are on the cover!

I tried to go out to her website but it seems to be down or no longer exist.

Kevin Osler