So I did a weighing thing

[gamewood]

So i wanted to know if using the RCS single use EMK would be lighter than the CTI case. I was comparing the 54mm 2800 case versus the CTI 6gxl case

CTI (including case. nozzle, taper rear closure, liner, and foward closure/delay charge) (without fuel grains) = 773 grams

RCS 54/2800 (case/liner, nozzle, forward closure) (without smoke grain, fuel grains, epoxy) = 774 grams

well there ya go

 

[fyrwrxz]

Cool! Answers a question I've never asked. Now I know. Did you know in Texas, they make purses out of Armadillos? You are welcome.

 

[Blast it Tom!]

I'm pretty anal about stuff like that myself, as I like to design mathematically and ya gotta have accurate numbers!

 

[mrwalsh85]

Now, what is the weight of the assembly methods utilized for each motor manufacturer? Some require gluing, others dont... More lube for one, and not the other?

Always gotta be that guy...

 

[gamewood]

Now, what is the weight of the assembly methods utilized for each motor manufacturer? Some require gluing, others dont... More lube for one, and not the other?

Always gotta be that guy...

Well I reported so y'all have a better starting point for decisions.

The RCS EMK will require epoxy to seal the nozzle and forward closure. The CTI can use lube, but I haven't done that.

So your question are in the <150g range.

The big issue is that CTI case is made to operate at a higher pressure. Idk and good luck getting it from CTI. The EMK has a max suggested of 800 psia.

 

[Getmore]

Iv never weighed propellant grains so would a Sparky grain be heavier than a white or other propellant?

 

[Neutronium95]

Iv never weighed propellant grains so would a Sparky grain be heavier than a white or other propellant?

I think that typically propellants with lots of metals will tend to be denser. Many smokey formulas use a ton of zinc, so that will crank up the density. Similarly, CTI IMAX propellant uses some weird ingredients to increase density without killing isp too much, in order to maximize the impulse for a given volume.

Here are the propellant masses for some CTI 75-5g motors as a point of comparison. I don't know if they all have the same core diameter, which would also affect the mass, along with the density.

Propellant	Motor Designation	Propellant Mass
Classic	M1400	2992g
IMAX	M1540	3624g
Smokey Sam	L1685	3773g
Skidmark	L1410	2875g
White	M1401	3508g
Red Lightning	M1810	3196g
Blue Streak	M1670	2956g
Green	M1160	3454g
Mellow	L395	3423g

 

[Getmore]

I think that typically propellants with lots of metals will tend to be denser. Many smokey formulas use a ton of zinc, so that will crank up the density. Similarly, CTI IMAX propellant uses some weird ingredients to increase density without killing isp too much, in order to maximize the impulse for a given volume.

Here are the propellant masses for some CTI 75-5g motors as a point of comparison. I don't know if they all have the same core diameter, which would also affect the mass, along with the density.

Propellant	Motor Designation	Propellant Mass
Classic	M1400	2992g
IMAX	M1540	3624g
Smokey Sam	L1685	3773g
Skidmark	L1410	2875g
White	M1401	3508g
Red Lightning	M1810	3196g
Blue Streak	M1670	2956g
Green	M1160	3454g
Mellow	L395	3423g

Aerotech has 3 reloads for the 54- 2800 case. the K 990dm is 1.149g the L1090w is 1.400g and K1050w is 1.261g CTI has 6 reloads in 6g the K711w is 1.398 and the K750r is 1.321 these are the two with the most weight. It looks like the white propellent has more weight to it in the 2800 case range. unless I missed some how.

 

[prfesser]

The sparking material most commonly used is roughly 2 1/2 - 3 times more dense as a typical APCP, so sparky propellant should be more dense, and heavier on a grain-for-grain comparison, than, say, a low-smoke propellant like Blue Thunder that has little or no metal. However, if the sparks are accompanied by black smoke, that may mean a lower density due to lower oxidizer content.

Heavy white or black smoke usually means lots of metals, so those propellants are also more dense than typical APCP.

 

[gamewood]

The CTI case measured was the 6gxl not the 6g. 6gxl is longer than the rcs single use case.

The question I was trying to answer was do I go low pressure and light weight OR power through it with a CTI motor. The analysis came down to weight only as the determining factor. Since CTi has more impulse/ weight that's what I'm going to use.

Except that imax motors aren't available which just fuds any decision.