Using MicroMaxx engines in odd application - Q2 igniter reliability?

[Rapidnadion]

Hi all! Been a few months since I last posted!

I just ordered a ton of Quest MicroMaxx engines to be used in our newest sinking model Titanic video. This model breaks in half, and we're going to use a MicroMaxx MMX-NE engine to sever the rubber band connecting the two halves of the hull.

My question is twofold:


How reliable are the Q2 igniters?
Will the engine fire if inverted?


Reliability is important, as if the engine fails to ignite, the model sinks intact, flooding and ruining the engine. Re-setting for a second take takes a while, so I want to be sure it fires correctly.

The engine will be mounted inverted, firing upward into the rubber band (and sending its exhaust through #3 funnel).

Thanks in advance for your advice, all! If you want to see a preview of the (still incomplete) breaking model, it's here:

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[BEC]

I've never had one fail. In a number of cases I've used one Q2 twice and once three times. As long as the bridge wire is against the propellant and sufficient current is delivered, it certainly should light.

Interesting project.

[gdiscenza]

I would probably use a double-dipped e-match to ignite a burn string that has been soaked in pyrogen. Using a motor to sever a rubber band sounds like one too many things that need to go exactly right to accomplish what you are trying to do.

Just my :2: ...

G.D.

[JPVegh]

I would probably use a double-dipped e-match to ignite a burn string that has been soaked in pyrogen. Using a motor to sever a rubber band sounds like one too many things that need to go exactly right to accomplish what you are trying to do.

Just my :2: ...

G.D.

This actually sounds like a really good idea. Unless releasing the tension on the rubber band is a necessary component in creating the effect. Which I suspect might be the case here. Perhaps a combination of the two is in order, use a match to burn through the rubber band. Or even a just few raps of nichrome around the rubber band. A rubber band under tension should give way fairly quickly once the curent is applied. It would be very easy to test. The smoke from a MMX or even a match may not look so realistic in scale.

BTW, if the preview is any indicator you should have a very convincing film when your done. Bravo!

[WillMarchant]

Instead of just a rubber band you could use a rubber band tied to a short length of fishing monofilament. Use cellophane tape to attach a Q2G2 to the monofilament.

[Rapidnadion]

I've never had one fail. In a number of cases I've used one Q2 twice and once three times. As long as the bridge wire is against the propellant and sufficient current is delivered, it certainly should light.

Interesting project.

Thanks!


I would probably use a double-dipped e-match to ignite a burn string that has been soaked in pyrogen. Using a motor to sever a rubber band sounds like one too many things that need to go exactly right to accomplish what you are trying to do.

Just my :2: ...

G.D.


This actually sounds like a really good idea. Unless releasing the tension on the rubber band is a necessary component in creating the effect. Which I suspect might be the case here. Perhaps a combination of the two is in order, use a match to burn through the rubber band. Or even a just few raps of nichrome around the rubber band. A rubber band under tension should give way fairly quickly once the curent is applied. It would be very easy to test. The smoke from a MMX or even a match may not look so realistic in scale.

BTW, if the preview is any indicator you should have a very convincing film when your done. Bravo!

Thanks to you both for the input! I've thought about alternatives such as those, but since stepping down to a MicroMaxx-size motor (down from an Estes 1/4A), I'm much more confident in the success of this idea. What the rocket motor idea gives us is greater ease of resetting the hull between takes, and easier set up than a home made e-match. I need precise control over when exactly the ship breaks, and with a reliable igniter, I have that with an engine.

As for smoke - the way it's rigged, some of it will go up #3 stack. But there's definitely going to be a lot in the breaking zone, as well - which we're okay with. When you're shooting between 60-210fps, smoke can be made to look pretty "big." :)

[Rapidnadion]

Instead of just a rubber band you could use a rubber band tied to a short length of fishing monofilament. Use cellophane tape to attach a Q2G2 to the monofilament.

Thanks, Will!

Actually, I've had the "what alternatives could I use?" discussion over at RCGroups already ... I'm very fond of the rocket engine idea for the above reasons. :)