# KBA K-750 reload casing question

### Help Support The Rocketry Forum:

#### NateLowrie

##### Well-Known Member
TRF Supporter
I have a few KBA K-750 reloads. They take a 54-2550 case, but from what I can tell it's not an Aerotech case. What case(s) are these loads built for?

#### cavecentral

##### Well-Known Member
Kosdon
Kosdon by Aerotech (KBA).

#### NateLowrie

##### Well-Known Member
TRF Supporter
Kosdon
Kosdon by Aerotech (KBA).
Know of anywhere to buy the hardware? None of the AT dealers seem to have it and my initial google searches are coming up blank.

#### Maxitout

##### Well-Known Member
That motor will fit in the AMW 54/2550 case. You'll have to get the whole motor assembly, with nozzle, bulkheads, etc. I think the only source for those is AMW/prox.com. I have a K-750, and also the K-1750 to fly, looking forward to both!

Phil L.

#### Johnly

##### Well-Known Member
Have a new gold colored 54/2550 Kosdon motor casing that I can spare.
$90 plus actual shipping. John #### NateLowrie ##### Well-Known Member TRF Supporter That motor will fit in the AMW 54/2550 case. You'll have to get the whole motor assembly, with nozzle, bulkheads, etc. I think the only source for those is AMW/prox.com. I have a K-750, and also the K-1750 to fly, looking forward to both! Phil L. I see that they have 1 in stock. Thanks for the suggestion. Have a new gold colored 54/2550 Kosdon motor casing that I can spare.$90 plus actual shipping.

John
Is it just the casing or does it include the nozzle, closure, and snap rings?

#### jimzcatz

##### Boss, Carolina Rocket Mafia
Ken at Performance Hobbies has that hardware. Loki 54/2000 will work, but case only. Will need AMW/Kosdon/Gorilla internals.

#### tfish

##### Well-Known Member
[QUOTE Loki 54/2000 will work, but case only.[/QUOTE]

How do you figure a Loki 54/2000 case will work with a KBA K750 reload?

A Loki 54/2000 case is 19.375 long. A Kosdon 54/2550 case is 28.660 long.

Tony

Last edited:

##### Well-Known Member
TRF Supporter
No the Loki 54/2800 case is the one you are looking for, but as noted already, you'll need someone else's bulkhead and nozzle. I'm not sure how different the nozzle is, but the case should fit.

#### cherokeej

##### Well-Known Member
You'll want to get that nozzle throat right. Use the wrong one and bad things happen...

#### jimzcatz

##### Boss, Carolina Rocket Mafia
[QUOTE Loki 54/2000 will work, but case only.
How do you figure a Loki 54/2000 case will work with a KBA K750 reload?

A Loki 54/2000 case is 19.375 long. A Kosdon 54/2550 case is 28.660 long.

Tony[/QUOTE]

My bad, it's the 54/2800. I have done it. My apologies for the misinformation.

#### NateLowrie

##### Well-Known Member
TRF Supporter
I ended up just getting the AMW 54-2550 from Gloria. The only thing I need to do is verify the nozzle bore is 0.660in. The AMW website didn't have any information on the bore size. I got 5 of these K-750 loads super cheap and figure I can use the hardware for EX as well.

#### jsdemar

##### Well-Known Member
I ended up just getting the AMW 54-2550 from Gloria. The only thing I need to do is verify the nozzle bore is 0.660in. The AMW website didn't have any information on the bore size. I got 5 of these K-750 loads super cheap and figure I can use the hardware for EX as well.
AMW nozzles

54/1050 0.4375
54/1400 0.484
54/1750 0.563
54/2550 0.656

54/1050 0.4375
54/1400 0.484
54/1750 0.563
54/2550 0.656

75/1700 & 75/2500 = 0.453"
75/3500 = 0.609"
75/6000 = 0.793"
75/7600 = 0.928"

#### Dave A

Ken has the nozzles and forwards. You can use a Loki fwd, and Ken show you a trick to use the Kosdon tracking smoke or Aerotech delays and a stack of o-rings. I keep them around so I can use any forward with any brand rrload.

#### jsdemar

##### Well-Known Member
Ken has the nozzles and forwards. You can use a Loki fwd, and Ken show you a trick to use the Kosdon tracking smoke or Aerotech delays and a stack of o-rings. I keep them around so I can use any forward with any brand rrload.
If you use a KBA load in anything but a Kosdon or AMW case, or with mods like you describe, it becomes a TRA Research motor.

#### NateLowrie

##### Well-Known Member
TRF Supporter
If you use a KBA load in anything but a Kosdon or AMW case, or with mods like you describe, it becomes a TRA Research motor.
John,

I would be using the AMW casing, nozzle, and forward closure which should be certified as it's mentioned in the instructions. Thanks for the clarification though. It doesn't really matter much for me anyway as to whether I fly it as EX or certified.

#### jsdemar

##### Well-Known Member
John,

I would be using the AMW casing, nozzle, and forward closure which should be certified as it's mentioned in the instructions. Thanks for the clarification though. It doesn't really matter much for me anyway as to whether I fly it as EX or certified.
I recommend greasing the liner well. They are thin/brittle liners (since AT doesn't have to warranty the case). I still have a K1750 left but I'm reluctant to use it. The other loads burned through the liner and scorched by AMW cases pretty bad. I've flown each of them at one time. The red M was in somebody else's case.

#### Dave A

If you use a KBA load in anything but a Kosdon or AMW case, or with mods like you describe, it becomes a TRA Research motor.
Since guessing he was already certified, just assumed everyone knew that. Not unless he is only flying at a NAR launch.

#### jsdemar

##### Well-Known Member
Since guessing he was already certified, just assumed everyone knew that. Not unless he is only flying at a NAR launch.
I posted that note in case it was read by 1000's of other readers of RTF. ;-)

#### Dave A

AMW nozzles

54/1050 0.4375
54/1400 0.484
54/1750 0.563
54/2550 0.656

54/1050 0.4375
54/1400 0.484
54/1750 0.563
54/2550 0.656

75/1700 & 75/2500 = 0.453"
75/3500 = 0.609"
75/6000 = 0.793"
75/7600 = 0.928"
The reload info sheet usually states the bore size of the nozzle, just in case it's not the same as AMW.

#### NateLowrie

##### Well-Known Member
TRF Supporter
I recommend greasing the liner well. They are thin/brittle liners (since AT doesn't have to warranty the case). I still have a K1750 left but I'm reluctant to use it. The other loads burned through the liner and scorched by AMW cases pretty bad. I've flown each of them at one time. The red M was in somebody else's case.

This is would make it a research motor I think, but you could try to soak the liner in Firefox's fire retardant liquid. Then, wrap the liner in pyro tape. Then grease. That should given sufficient protection against burn through.

Aaa

Last edited:

#### jsdemar

##### Well-Known Member
This is would make it a research motor I think, but you could try to soak the liner in Firefox's fire retardant liquid. Then, wrap the liner in pyro tape. Then grease. That should given sufficient protection against burn through.
Greasing a commercial motor's liner doesn't make it a research motor. Modifying the liner, if not recommended by the manufacturer, would be a non-certified assembly.

The bottom line is that the KBA liners are generally a poor fit, thin, and brittle. I've never seen them NOT burn through.

#### jsdemar

##### Well-Known Member
The reload info sheet usually states the bore size of the nozzle, just in case it's not the same as AMW.
The nozzle throat for the KBA loads has to be the same as the nozzle for the Kosdon/AMW case it was certified with. There are no substitute nozzles available. The instructions from AT for the "Animal Compatible" loads list the nominal throat diameter. It should match the ones I've listed.

Here's the instructions for 54mm KBA load. It says 0.660" nozzle. I've measured mine after many flights and it is 0.663". Brand new they are 0.656" min drill. All within a percent difference, so not a problem. Throwing in a Loki nozzle would be a problem.

#### Loki Research

##### Motor Manufacturer
Throwing in a Loki nozzle would be a problem.
To add to what John said, it's a problem not just for the throat diameter in most cases (it is a .656 for the 54/2800), but the size/shape, liner step dimensions are all going to be different between Loki Research and others. Sure it can be "make" to work, but don't assume that it will work just because the throat is the right size, because it won't work without modification to something somewhere.

John, I can send you a sample of my convolute liners if you'd like to try the fit around your KBA grains. Send me an email if you'd like to try.

#### jsdemar

##### Well-Known Member
To add to what John said, it's a problem not just for the throat diameter in most cases (it is a .656 for the 54/2800), but the size/shape, liner step dimensions are all going to be different between Loki Research and others. Sure it can be "make" to work, but don't assume that it will work just because the throat is the right size, because it won't work without modification to something somewhere.
I should have explained further. Thanks!

John, I can send you a sample of my convolute liners if you'd like to try the fit around your KBA grains. Send me an email if you'd like to try.
The OD of the casting tube will not fit in any of the standard liners. Gary squeaked more propellant in at the risk of ruining the (other manufacturer's) casing.