X1.4: A 24mm MD prototype story.

dr wogz said:

I was hoping this thread would have pushed 20 pages by the end of the year..

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I bet we can help it along.

Problem with G-145 recovery. Wind drift from chute at 7500ft Apogee deploy. The last windy launch at Sod Farm had me rethinking about Apogee deploy a 9-12” chute this high? The waiver went to 10k ft I brought X1.4 along but didn’t fly it with the 16-60 mph gusts at altitude. Thought about a 2” x 20” streamer but descent rate sims 23 m/s.

So I’ve got the main set to 900 ft on Telemini V3. About switches, I can’t seem to find one small enough. So it’s either packing this entire cramped rocket of a thing live at the pads or twist and tape maybe???? Whatever I’ll need to sand out a groove in that nosecone sometime for a FireWire. I’m leaning towards electronic deploy main if I can figure out a way to do it safely.

Andrew_ASC said:

Wind drift from chute at 7500ft Apogee deploy. The last windy launch at Sod Farm had me rethinking about Apogee deploy a 9-12” chute this high?

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Use a cable cutter.
https://aeroconsystems.com/cart/launch-recovery/cable-cutter-by-archetype-rocketry/

Andrew_ASC said:

About switches, I can’t seem to find one small enough.

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Fingertech Robotics switches. IIRC it was Crazy Jim that put me onto them. The AeroPac 100k team also used/uses them? It's the best switch I've ever seen if you're looking to conserve space.

https://www.fingertechrobotics.com/proddetail.php?prod=ft-mini-switch

Magnetic switch from featherweight.

Eric said:

Magnetic switch from featherweight.

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Given Andrew's using a Telemini for tracking and deployment duties wouldn't that require the mag switch to have its own lipo?

Featherweight screw switch might be an option but I don't think they're incredibly reliable for repeated use.

Yeah I don’t see how a mag switch is fitting in there or a cable cutter lol. It’ll be good enough to get a micro switch and one deploy charge for the main in there in my humble opinion. I can set the altimeter to kick the main out at any alt I wish.

Fingertech switches are pretty small and a sampling hole is needed anyway. Prairie Twisters are tiny as well.

Would one of these switches work?
The other is out of stock?

https://botsdepot.com/products/kinetic-mini-power-switch

Those look pretty good, though if you have access to a 3d printer there's a number of similar switch files collected here on a forum thread.

I just called for the kinetics switch dimensions, it’s a half inch, by half inch, by quarter inch. This is a combat robot switch so it should be robust.

Andrew_ASC said:

Would one of these switches work?
The other is out of stock?

https://botsdepot.com/products/kinetic-mini-power-switch

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Yes, that's the Fingertech Robotics switch. It's identical to the switch link I posted up-thread.

Those are the ones...great little switch.Buy it direct cheaper.

https://www.fingertechrobotics.com/proddetail.php?prod=ft-mini-switch

Ordered the switch and swapped the main from a 12” to a 9” top flight recovery thin mill chute. Seems roomier.

Are you using a cable cutter?

Got my combat robot switch. Now all I need is some MJG firewires and a soldering iron.

Soldered the switch last night and picked up a 3/32nd Allen from
Ace after work.

Are you just deploying your parachute at apogee?

You said earlier that you have your main set for 900 feet on your altimeter. But you just can't let it come in ballistic until nine hundred feet and then blow the main.

Eric said:

Are you just deploying your parachute at apogee?

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Electronically at 900 ft is the new plan. Just a main charge then. Let me know if bad idea.

So what will happen at apogee? Or are you just planning on the rocket Free Falling until the main blows at 900 feet?

If that's your plan to not have any apogee event. It is completely unsafe and should not be flown that way. If your electronics fail you already have a high speed carbon fiber death dart coming in.

Even if your electronics work. You will most likely shred all of your recovery gear opening at that high of speed

Guess I need a cable cutter thanks for the advice Eric.

I don't know the exact dimensions of your body tube. But based on that 6xl case. You have 6-8" for recovery? 4" wide Mylar streamer, by as much as you can roll in there. Or a much smaller parachute.

I always assumed that rocket would out fly the delay time on any motor. So altimeter deployment would be necessary. Just pop the streamer or small parachute out at apogee.

It's okay if you come down with a much higher descent speed. Unless you're landing on a hard surface the motor case and nozzle will hit first. But you have tracking if it drifts a little bit

Are you removing the motor charge? You may be able to rig your current altimeter as a hot wire cutter. I’ve done it with a Quark and have posted it on TRF. So...
motor eject near apogee (if the delay is long enough- or a drogue charge and remove the motor charge)
Descend on a small streamer or drogueless to main deploy altitude
Main cuts the line bundling the main.

You might be able to rig your cable/wire cutter to -un- reef the main instead of freeing a bundle.

Either way, the trick (like with a JLCR) is to keep the chute furled while the rocket falls in multiple non-aerodynamic parts. And those parts tumble about a lot, especially drogueless. So you might want to practice with one of your other rockets at 1500’, release at 500’ before trying 7500’.

The delay is long enough on the G-145 motors, it’s a 15s delay. Or I can remove the delay and run another FireWire plus deploy charge on the Apogee channel. Then I can use the “main channel” on Telemini to fire the cable cutter charge at a lower set altitude. I can test it on a D15T-6 rocket motor once I get another 24/40 RMS casing. It probably won’t fly until October.

My biggest concern is will a 9” main fit with a cable cutter around it into a 24mm tube. Length doesn’t seem to be the issue. I guess there’s only one way to know which is buy a cable cutter and try.

That is a great idea. Having a parachute reefed shut with monofilament fishing line. It would act as a drogue or streamer. And a hot wire cutter would work very well.


You could even tape your fire wire ignitor to the monofilament. That would cut it right open

I still say pop it at the top and use a decent streamer.

I use ‘happy birthday’ banners as streamers. About 8”x12’. Will fit in 29mm min diameter easy. Mylar, so highly visible on a sunny day.

My Quark Release barely fits in BT55. I have a sneaking suspicion that a pyro cable cutter is for 3”+ airframe.

I love the idea of FireWire cutting fishing line wrapped once around it.

timbucktoo said:

I still say pop it at the top and use a decent streamer.

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+1 done it many times for both 24 & 29minimum's......nothing to foul or go bad in a tiny space. You can easily get 30-40ft of lineman's streamer in there. Wrap around a dowel or pencil & stuff inside.