Looking for a Kosdon L3000 thrust curve

[Neutronium95]

I might have a lead on one of these motors. I haven't been able to find a thrust curve for one online yet, and I was wondering if anyone on here had one.

 

[charrington]

I would contact @Loki Research or the owner of AMWx . They might have a lead

 

[Loki Research]

From an old Rocksim file. I'm not sure it's that accurate the from the entry, but it's all I have....

;
Kosdon L3000 best guess. Sean McAndrew
L3000 54 633 5-10-15 1.65 3.6311 KOS
0.0 3000.000
1.099 3000.000
1.1 0.000
;

 

[GalantVR41062]

https://www.rocketryforum.com/threads/kosdon-l3000-wow.18878/
This thread talks about the 44" long 54mm L motor. Loki has a couple 54mm L reloads.

 

[MClark]

Unlikely it was ever put on a test stand. A motor being certified wasn’t important then.
Called "The Safecracker", when first one was static fired (buried in the ground) someone said, "You could bust open a safe with that thing!"

 

[jsdemar]

I made a clone of the 54mm L3000 casing for someone about 18 years ago. AWM had reloads leftover from Kosdon East but no hardware left. 36" of propellant, four "fast" grains and bottom "slow" grain.

There was also the Kosdon M3700 with 40" of propellant in a 2.5" case.

Now that I have a Lathe with a 3" through hole and a 100" bed, these hardware clones will be easier to make.
https://photos.app.goo.gl/opz6vAVRPDrGQPL77

 

[3stoogesrocketry]

 

[FredA]

Questions on this:
1 - Which grains had inhibited ends?
2 - WHY inhibit the ends? Seems counter-intuitive except from a mass-flux perspective, but the MF doesn't seem bad without inhibiting.
3 - What did Frank use to inhibit the ends - was it really an inhibitor, or just a sturdy spacer?

 

[jsdemar]

That agrees with what I have...

Size	Certified	Old	Burn	# of	"L"	Grain	Burn	Core	"S"	Nozzle​
Outside Dia.	Description	Description	Time	Grains	inch	#	Type	Dia.		Diameter​
	(newton-seconds)	(newton-seconds)	(sec)					(inch)	(inch)	inch	Drill #
2 1/8" *		L3000 - 3300 NS	1.1	4	9.00	1	F	31/32	-	0.8433
						2	F	31/32	-
						3	F	1-1/16	1/4
						4	S	1-1/16	1/4

 

[MClark]

Inhibitors were some urethane resin Frank had.
I believe he got it as a sample.

 

[jsdemar]

Questions on this:
1 - Which grains had inhibited ends?

The bottom two, one end each.

2 - WHY inhibit the ends? Seems counter-intuitive except from a mass-flux perspective, but the MF doesn't seem bad without inhibiting.

Reduce the resonance at startup.

3 - What did Frank use to inhibit the ends - was it really an inhibitor, or just a sturdy spacer?

It was a toxic polymer he mixed using MOCO.

 

[3stoogesrocketry]

Questions on this:
1 - Which grains had inhibited ends?
2 - WHY inhibit the ends? Seems counter-intuitive except from a mass-flux perspective, but the MF doesn't seem bad without inhibiting.
3 - What did Frank use to inhibit the ends - was it really an inhibitor, or just a sturdy spacer?

Per the pictures I posted. Grains 4 and 3 each had a 1/4 inch polymer grain support ring added to their bottoms .

 

[FredA]

So it sounds like more of a "sturdy spacer" as I suspected.
John - what is that "S" parameter in your table? Grain-end shaping?

 

[Loki Research]

https://www.rocketryforum.com/threads/kosdon-l3000-wow.18878/
This thread talks about the 44" long 54mm L motor. Loki has a couple 54mm L reloads.

The Loki 54/4000 case has the same length & diameter spec as the Kosdon L3000 case, but with a thrust ring . They are the same, only I cram 41.9" of propellant inside with a much smaller bore and have a single use nozzle with a much larger exit. I'm told that most of the L3000 graphite nozzles ended up being single use anyway from cracking. I had the same results when I tried graphite nozzles with this case too.

I really should have named it the 54/5000 but I didn't want to sound boastful since my reloads had not been certified at the time. It would be much more accurate though.

 

[jsdemar]

So it sounds like more of a "sturdy spacer" as I suspected.
John - what is that "S" parameter in your table? Grain-end shaping?

S = Slow, F = Fast.

 

[StreuB1]

IIRC the inhibitor he used was from Dow and was a urethane.

You can use a medium durometer casting urethane as a replacement.

 

[J Blatz]

Unlikely it was ever put on a test stand. A motor being certified wasn’t important then.
Called "The Safecracker", when first one was static fired (buried in the ground) someone said, "You could bust open a safe with that thing!"

This is the answer.

 

[Neutronium95]

From an old Rocksim file. I'm not sure it's that accurate the from the entry, but it's all I have....

;
Kosdon L3000 best guess. Sean McAndrew
L3000 54 633 5-10-15 1.65 3.6311 KOS
0.0 3000.000
1.099 3000.000
1.1 0.000
;

Thanks for that. I just needed to adjust the motor length to match the 54/4000 case.

Incidentally, I'm considering also flying a 54/4000 motor in the same rocket. Have you considered offering a puck style forward closure with no delay grain option for those motors? Every inch of rocket length that can be saved really helps the altitude, and the extended closure essentially forces the rocket to be 2" longer than it needs to be.

 

[FredA]

No - the "S" with units of inches that is to the right of the core size in your table.
Values are "-" and "1/4"

 

[jsdemar]

No - the "S" with units of inches that is to the right of the core size in your table.
Values are "-" and "1/4"

“S” for spacer insulator length.

 

[kjhambrick]

From an old Rocksim file. I'm not sure it's that accurate the from the entry, but it's all I have....

;
Kosdon L3000 best guess. Sean McAndrew
L3000 54 633 5-10-15 1.65 3.6311 KOS
0.0 3000.000
1.099 3000.000
1.1 0.000
;

I've got exactly the same entry in a June 1998 RASP.ENG file.

Even the same comment line.

The RASP header entry lists the motor dimensions as 54mm x 633 mm ...

HTH

-- kjh

 

[Neutronium95]

Here's the file with the correct case length. Upon comparing to the Loki 54/4000 loads, the masses seem to be roughly in the ballpark, with higher casing mass and a lot less propellant mass. If this does end up happening, I'll try to publish a thrust curve with accurate masses. Maybe even try to back out motor performance from the rocket acceleration.

;
L3000 54 1111 5-10-15 1.65 3.6311 KOS
0.0 3000.000
1.099 3000.000
1.1 0.000
;

 

[kjhambrick]

Here's the file with the correct case length. Upon comparing to the Loki 54/4000 loads, the masses seem to be roughly in the ballpark, with higher casing mass and a lot less propellant mass. If this does end up happening, I'll try to publish a thrust curve with accurate masses. Maybe even try to back out motor performance from the rocket acceleration.

;
L3000 54 1111 5-10-15 1.65 3.6311 KOS
0.0 3000.000
1.099 3000.000
1.1 0.000
;

Thanks @Neutronium95 !

Do the motor and propellant masses match what you have ?

The reason I ask is I've got an assembled Kosdon 'L Motor" in my magazine that I bought from Frank at ROCStock or a Turkey Shoot years ago.

I recall it being an agressive L Motor that Frank wanted to fly in my 4-inch cardboard Iris but I chickened out.

I've not really looked at it for years but I don't think what I have is over a meter long.

Must be a different L-Motor .. I'll take a picture tomorrow.

-- kjh

 

[Neutronium95]

Do the motor and propellant masses match what you have ?

I don't have the motor on hand to measure those yet. I was just correcting the case length. I'll post an updated one once I have accurate measured masses.

 

[kjhambrick]

@Neutronium95 --

This is what I have for the 54 mm Kosdon L-Motor:

Length is 28.75 inches

Mass: a little more than 2.5 Kg ( it overflowed the only accurate scale I have anymore but it showed about 6 lb on a bathroom scale )

I could measure the external nozzle orifices if you like.

Pictures:



HTH and have fun !

-- kjh

 

[3stoogesrocketry]

@Neutronium95 --

This is what I have for the 54 mm Kosdon L-Motor:

Length is 28.75 inches

Mass: a little more than 2.5 Kg ( it overflowed the only accurate scale I have anymore but it showed about 6 lb on a bathroom scale )

I could measure the external nozzle orifices if you like.

Pictures:

View attachment 607153View attachment 607154View attachment 607155

HTH and have fun !

-- kjh

You sir most likely have a L1860 fast in there. The other loads were a L850 slow and a K8xx Dirty Harry. The L1860 is comparable ( slightly less total impulse) to the Loki L1400

 

[kjhambrick]

You sir most likely have a L1860 fast in there. The other loads were a L850 slow and a K8xx Dirty Harry. The L1860 is comparable ( slightly less total impulse) to the Loki L1400

Thanks @3stoogesrocketry

It was so long ago, all I remember is sitting around and visiting with Frank while he grabbed the components from his car to build me an L-motor for a new glass rocket I was building.

An L1860 sounds only about half as intense as an L3000

Thanks again and sorry about the noise.

-- kjh

 

[J Blatz]

@Neutronium95 --

This is what I have for the 54 mm Kosdon L-Motor:

Length is 28.75 inches

Mass: a little more than 2.5 Kg ( it overflowed the only accurate scale I have anymore but it showed about 6 lb on a bathroom scale )

I could measure the external nozzle orifices if you like.

Pictures:

View attachment 607153View attachment 607154View attachment 607155

HTH and have fun !

-- kjh

This looks to be a 54/2560 with 24" of propellant. A stout motor, but nowhere near the mayhem that is the L3000.

 

[tfish]

Tony

 

[tfish]

Tony