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I was having a look at my M685 reload and noticed that the nozzle was a single throat instead of a medusa like the drawing on RCS shows. Has there been a change to the reload, or have I gotten the wrong nozzle?
 

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Maybe? I'm just going off what the Aerotech supplied drawing says.
The drawing is out of date. The last M685 I flew, last year, had a single throat nozzle and I wouldn't say it was particularly short, maybe post a pic?
 
Sweet, that means I can use the 75mm tapered aft closure with it. the medusa nozzles are too short to use with it.

M685 does indeed now use the single throat nozzle.

M685 single throat nozzle is submerged within the tail cone closure by 0.225" (see my drawing below)

Note: Drawings/models are produced by me from my own hardware and for my own personal use, for my own design projects. They are not available, please do not ask.


1715737177161.png
 
TRA L3 #1 and AeroTech/RCS VP Karl Baumann with a partial inventory of our larger high-power motor casings.
View attachment 645710
Say, could I get seven of these, and five of those, please, and maybe four of those over there? And, before I forget, add six of those guys right behind them over there?
"Partial inventory"? There IS hope for us after all! (Mr. Baumann is smiling for a reason!) Thank you for the "drool over" photo!
 
Following up on the M685 nozzle change thing, I've noticed that Thrust Curve and Aerotech list different total impulses for the motor. Is this difference due to the nozzle change? Aerotech says it makes 7,741 Ns, while Thrust Curve has it at 7,561 Ns.
 
Where do you source the wires used in the leads for the First Fire igniters? I need igniters that can fit in a .064" throat and making them out of that wire has the best result. I'm 90% certain it's 27-28 gauge two conductor solid core wire. I can't find that, only stranded two conductor wire, or single conductor solid core. Working with leftover First Fire wire has been far less tedious to make igniters out of than leftover Twiggy wire.
 
Following up on the M685 nozzle change thing, I've noticed that Thrust Curve and Aerotech list different total impulses for the motor. Is this difference due to the nozzle change? Aerotech says it makes 7,741 Ns, while Thrust Curve has it at 7,561 Ns.
Not sure, it could be the difference between what we measure on our stand vs. TMT numbers.
 
Where do you source the wires used in the leads for the First Fire igniters? I need igniters that can fit in a .064" throat and making them out of that wire has the best result. I'm 90% certain it's 27-28 gauge two conductor solid core wire. I can't find that, only stranded two conductor wire, or single conductor solid core. Working with leftover First Fire wire has been far less tedious to make igniters out of than leftover Twiggy wire.
We don't actually source the wire but we purchase the completed wire assemblies from a vendor.
 
Following up on the M685 nozzle change thing, I've noticed that Thrust Curve and Aerotech list different total impulses for the motor. Is this difference due to the nozzle change? Aerotech says it makes 7,741 Ns, while Thrust Curve has it at 7,561 Ns.
Just to keep things in perspective, you're talking about a 2% difference in total impulse. It could be from a variety of sources (nozzle, air temp, air density, mixing speed, etc.) but it should have negligible impacts on simulated or actual flight results.
 
Does Aerotech make any reloadable motors that also have a long thrust duration like the F10/G8/G12 for a TVC rocket?

For mid power, there is the 29/120 G25 load (~5 sec burn) and the 32mm G12RCT (which is on the 'seasonal' motor list, available once a year, although some dealers have limited stock of the reloads)

The real long burners like the G8 or G12 are end-burners. Those produce significant heat soaking near the nozzle, making them hard on reloadable aluminum casings. As I understand it, that is why the machined aluminum casing used on the K250 is a single use item (but it's a C-slot, not end burner).
 
The real long burners like the G8 or G12 are end-burners. Those produce significant heat soaking near the nozzle, making them hard on reloadable aluminum casings. As I understand it, that is why the machined aluminum casing used on the K250 is a single use item (but it's a C-slot, not end burner).

I've thought about doing much shorter-burn versions of these in short HP cases as lower-total-impulse MPR, but that gets into EX territory.
 
Thank you all for the idea and we will consider it. The big downside is that it would increase the “pig in a python” effect with regard to lead times increasing with an even larger volume of orders arriving all at once.
The problem with a seasonal order around Black Friday for us in the Midwest is that our high power season runs from November/December until April due to crops. We would have to plan our needs two years out which ain't happening. The only good time for seasonal orders is year-round. :(
 
Where do you source the wires used in the leads for the First Fire igniters? I need igniters that can fit in a .064" throat and making them out of that wire has the best result. I'm 90% certain it's 27-28 gauge two conductor solid core wire. I can't find that, only stranded two conductor wire, or single conductor solid core. Working with leftover First Fire wire has been far less tedious to make igniters out of than leftover Twiggy wire.
I have been using this cheap: https://www.amazon.com/Solder-Coate...+tin+plated+copper+wire,industrial,120&sr=1-3
You can also use Kynar insulated wire wrap wire but a lot more expensive and silver plated.
 
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