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Mach 1+ Fins and Igniting Staged Motors w/Motors

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eduncan911

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I'm posting in the Mid Power section to get experiences with those with F-G reloadables and Mach experience.

I'm having a crazy thought of modifying my Estes Comanche 3 for 3x 24mm motors. Stage 1 and 2 are only 70mm, which limits me to something like an Aerotech F24 reloadable. Stage three could squeeze however long 24mm I could find (OpenRocket lists a G55 sucker!).

At Mach 1.2, with F24+F24+G55, needless to say the balsa fins are out. But, I won't be able to do TTW fin tabs.. Since the body tube is 24mm.

I'm thinking of some lightweight electrics like building a cheap gps and altimeter.


The main questions I have are:

1. Can reloadable, maybe Aerotech, ignite from staged motors' ejection charges?
2. There is zero room for the ejection charge pressure to escape, thereby possibly ejecting the booster, before igniting the upper stage. Is that an issue or is there some other trick to ignite?

Most that I see here in this forum uses electronics to ignite the upper stages.


Ps, attached is image for a giggle.

Screen Shot 2017-08-03 at 9.57.36 AM.jpg
 

rharshberger

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Composite APCP motors are much harder to light than black powder motors like Estes, while I have heard of a few attempts at AP to AP direct staging they were erratic to say the least which is why we use electronics. I have heard as well that AP to BP direct staging is slightly more reliable, again its all secondhand info from the dark past, maybe others on TRF have firsthand experience.
 

dhbarr

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AP to BP works best if you have access to quick match, and you need about a 4-second coast in the middle.

If I was trying to do AP-AP staging, stubby CTIs that have the additional igniter chunk would seem to be the way to go. Since you're in 24mm, f55 f55 g65 seems theoretically possible, but you'd have to deal with the knurled thrust rings. Again, just theory.

For any of this, -please- get it reliably correct on the thrust stand and home pasture before even thinking of taking it to the club. Be aware that some RSOs may consider AP-AP to be not intended by the manufacturer, therefore EX.

Cheers!
 

dhbarr

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Oh, and if it's just mach1 you're after, check out a minimum diameter g65 by itself, then call Charlie at Carolina Composites.
 

Zeus-cat

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The Apogee Aspire can do Mach 1. It is a fire and forget rocket. Fire it and forget about because you will never see it again. I have only seen one launched and it was lost.
 

dhbarr

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That's what Eggfinder Minis and/or Telemini V3's are for :)
 

CORZERO

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Fins:

https://hobbyking.com/en_us/2-200-300mm-carbon-fiber-plate.html

Staging:

https://www.featherweightaltimeters.com/The_Raven.php

Run igniter leads externally from a payload section through a small hole in the third stage airframe? Perhaps through a small conduit of some sort (thin-wall 2mm carbon tubing) fixed to the outside of the airframe? Insert igniter leads into small openings in the top of the booster sections? Create small, diametrically opposed apertures for igniter leads as well as venting purposes?
 
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eduncan911

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You know, I started this thread as just a thought experiment. Knowing the fins wouldn't hold up to the speed, ejection charges would blow the boosters away, as well as not really igniting the upper stage, and I'd most likely not find electronics small and light enough.

But with all of your info... Wow, is this becoming a possibility?

Thank you all! I'll take the time to digest each link and post and will be back.

PS, running thin wires external... Now that's a though.

Ps2. Main goal was altitude in an Estes Rocket with a chance of recovery.

Ps3, 3x D12 still takes it to 3600 feet. Three C11, to ,2800 - maiden voyage I guess?
 

DavidMcCann

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The trouble is BP motors are endburning, so easy to light with the flame of ejection/motorburnout.
Most AP are slot or core burning and need to start burning at the top. Going to need electronics to stage them.
 

eduncan911

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How would I glue/mount/bond carbon fiber fins to the airframe so that they wouldn't be ripped off at those speeds? I thought I had mount them TTW with tabs for speeds close to Mach 1.

Staging:

https://www.featherweightaltimeters.com/The_Raven.php

Run igniter leads externally from a payload section through a small hole in the third stage airframe? Perhaps through a small conduit of some sort (thin-wall 2mm carbon tubing) fixed to the outside of the airframe? Insert igniter leads into small openings in the top of the booster sections? Create small, diametrically opposed apertures for igniter leads as well as venting purposes?
Looks like a possibility. Need to add in the weights of batteries and devices.

Oh, and if it's just mach1 you're after, check out a minimum diameter g65 by itself, then call Charlie at Carolina Composites.
Will inquire. :)

That's what Eggfinder Minis and/or Telemini V3's are for :)
Looks like a good option! I'll read up on them. But, I don't plan on getting a HAM license.


Composite APCP motors are much harder to light than black powder motors like Estes, while I have heard of a few attempts at AP to AP direct staging they were erratic to say the least which is why we use electronics. I have heard as well that AP to BP direct staging is slightly more reliable, again its all secondhand info from the dark past, maybe others on TRF have firsthand experience.
AP to BP works best if you have access to quick match, and you need about a 4-second coast in the middle.

If I was trying to do AP-AP staging, stubby CTIs that have the additional igniter chunk would seem to be the way to go. Since you're in 24mm, f55 f55 g65 seems theoretically possible, but you'd have to deal with the knurled thrust rings. Again, just theory.

For any of this, -please- get it reliably correct on the thrust stand and home pasture before even thinking of taking it to the club. Be aware that some RSOs may consider AP-AP to be not intended by the manufacturer, therefore EX.

Cheers!
The trouble is BP motors are endburning, so easy to light with the flame of ejection/motorburnout.
Most AP are slot or core burning and need to start burning at the top. Going to need electronics to stage them.
Thank you all! That's what I needed to know.
 

CORZERO

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Just throw a few bucks and some clever engineering techniques at it. It'll fly. Surface mount the carbon fins with a good epoxy. Add some light fillets to it. You'll be fine. Tracking is obviously necessary if you want it back. Bt50 is 24mm/ish ID so there are compatible electronic components out there.

Without an .ork to play with I can't comment definitively about the integrity of the structure through mach transition/max Q. If it spent a lot of time under stress I'd want to run FinSim. I would guess that with the added weight of the necessary equipment to control the flight you may no longer be at or above mach, but that doesn't necessarily get you out of the woods in terms of stress to the vehicle either. With the information I have, my general impression is that it will stay intact and be a great flight.
 
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