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The smallest composite staging system

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Nytrunner

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I don't really want to go down as the safety naysayer, but....

We stage LPR rockets all the time without safety checks. It's not really any different to use a timer for 18 mm and 24 mm composite motors.
Valid, the safety risk is slightly less with lo-power rockets. (although @jlabrasca has some good graphics on the lethality or safety of model rockets and tissue damage)

I will draw a distinction though. Now we have 18mm composite motors. They don't stage immediately like direct/gap staged blackpowder, and they have a pressurization transient that can be different with each flight. Complication must be accounted for
 

Ez2cDave

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That "Simple Timer", sold by Apogee, looks way too "fiddly" . . . Even the guy who designed was fumbling around with it !

Dave F.

 

ThreeJsDad

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I don't really want to go down as the safety naysayer, but....

We stage LPR rockets all the time without safety checks. It's not really any different to use a timer for 18 mm and 24 mm composite motors.
I agree and I actually prefer to handle APCP motors over LPR BP motors. I think the APCP motors are more stable with fewer issues.
 

Ez2cDave

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That "Simple Timer", sold by Apogee, looks way too "fiddly" . . .

Even the guy who designed the unit was fumbling around with it !

Dave F.

 

ThreeJsDad

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That "Simple Timer", sold by Apogee, looks way too "fiddly" . . .

Even the guy who designed the unit was fumbling around with it !

Dave F.

He may have been nervous, He looked really nervous even before he started talking. I am not saying the unit is something I am going to run out and purchase. It might be interesting to hear from some folks who have actually set one up and flown it.
 

n27sb

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I recently purchased the Apogee Simple Timer.
I found it to be very simple to set up. I did a couple of test ignitions using only a 2s 200 mah lipo. It easily lit First Fire Mini igniters.
 

Cameron Anderson

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Maybe I need to do a timer, since Apogee is getting $85 for theirs...
I'd buy one of yours if you did.
Something small (29mm tube), wifi capable, with a tilt limit and altitude check. I don't know how hard all that is but I believe there is a market for it.
 

Nytrunner

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Maybe I need to do a timer, since Apogee is getting $85 for theirs...
That's a great product kit idea. A compact staging timer with safety inhibits is something worth learning to solder for.

Just because the smaller staged rockets are 'less dangerous' if something goes pear-shaped doesn't mean they wouldn't benefit from having the same safety feature programming available to them

(heck, if it's just a tweaked Quantum, that reduces your R&D and inventory cost!)
 

mbeels

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The Eggtimer Classic can be used for staging and air starting, it fits in BT-55. $35 and super easy to build and use.
 

mbeels

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How do you do that?
The manual goes into lots of details (Cris' documentation is excellent!). You only get 2 channels with the Classic, so you get 1 air start, plus one pyro event. I think that the usual configuration is air start -> motor ejection at apogee, and then main pyro event at set altitude. I've done it once with the Classic and it worked great. I later switched to the Proton because it does so much more (although it is slightly wider, I think).
 

thequick

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The manual goes into lots of details (Cris' documentation is excellent!). You only get 2 channels with the Classic, so you get 1 air start, plus one pyro event. I think that the usual configuration is air start -> motor ejection at apogee, and then main pyro event at set altitude. I've done it once with the Classic and it worked great. I later switched to the Proton because it does so much more (although it is slightly wider, I think).
iirc you can use the aux channels on the classic for more events but you have to get creative to get the outputs to light a charge.
 

Rocketjunkie

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OverTheTop

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Don't forget to allow for the slow starting of the composite motors in the delay calculations. Err on the side of safety by going short where possible, to avoid ignition when too fat from vertical.
 

cerving

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If you're OK with single deploy in the sustainer you can fit an Eggtimer Quantum into a BT50... just leave off the terminal block and headers. I flew an Estes Mongoose that way... with a D21 in the bottom and a D10 in the top. I also had an Eggfinder Mini in the nose cone... good thing, because I needed it.
 

gary7

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The Perfecflite miniTimer4 is only $49.95 but finding one is a problem.
 

Funkworks

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So after planning this for almost 1 year (apparently), I decided to start my staging adventures with Loc's 38-inch Terrier booster. Thanks for the tips.
 

Cameron Anderson

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So after planning this for almost 1 year (apparently), I decided to start my staging adventures with Loc's 38-inch Terrier booster. Thanks for the tips.
It's a fun one - great way to start. Plenty of room to do a lot with, but still small enough you need some good planning.
 

Glorious

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I’ve been there and done it with staging BP motors, so I’m now starting to look into staging composite motors. Here’s what I have in mind:
  • 2 APCP motors.
  • Lowest power possible. I’m totally fine with 2 small Aerotech D motors.
  • Lowest altitude possible. I couldn’t care less about altitude. I just want a safe, successful build.
  • Debating between a simple timer and direction sensing (not the first one to debate this, huh?).
  • Don't mind if it takes a entire year to build and to fund.
Until I’ve read this entire forum section, any suggestions for kits, parts, information sources and the current status of safety concerns are welcome.
How about a 13mm EX-C motor powered 2 stage with GPS telemetry.
We put it in a shadow box to present to the TARC teams that got disappointed watching large motors fly while they were flying these small F motors. It demonstrates how hard it can be with small projects that have a goal.
It uses a timer for staging powered by a super capacitor.
The dual deployment altimeter runs on a 1.2V NiMH battery.
And the GPS system runs on a LiPo battery.
And the Altimeter has a 90dB buzzer to find it after the GPS gets you close.
 

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shockie

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Well, "back in the day", before electronic staging, we used Thermalite strands, ignited by the flame from the motor below it.

The burn time could be shortened by sheathing or partially-sheathing the Thermalite. Sheathed Thermalite burns VERY ( extremely ) fast.

BTW - ( gasp ) we lit the motors inside the coupler ( lined with foil or coated with JB Weld ) . . . We did not use Drag Separation or Separation Charges . . . Ah, the "Good, Old Days" !

Naturally, Thermalite is no longer available . . .

Dave F.
make your own......the wayback machine is your friend

 
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