Kosdon 2.5 rocket

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The grains for the 2.5" hardware are on the right. K453 with a 5.16 sec burn.

36150392990_0bfc319708_z.jpg


Tony
 
I'll be test flying this at XPRS, next weekend. The stock motor with Swamp Gas is all loaded up. 16 inches of propellant, K450 2337n/S 5 sec burn.

The motor I'm going to make for Balls looks like..roughly30 inches of propellant L875 4110n/S 4.7 sec burn

Tony
 
I'll be test flying this at XPRS, next weekend. The stock motor with Swamp Gas is all loaded up. 16 inches of propellant, K450 2337n/S 5 sec burn.

The motor I'm going to make for Balls looks like..roughly30 inches of propellant L875 4110n/S 4.7 sec burn

Tony

Good luck Tony! Swamp Gas...like you have a love/hate relationship with that stuff. Haven't mixed it in nearly a decade...like the burn characteristics anyway. Have fun brother!
 
I just opened up the used motor and found a couple of things..

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The BMS liner held up pretty good to Swamp Gas (which is a pretty mild formula) The liner was a little burned at the noz end. It came out easy. I used PAM cooking spray on the liner.

The nozzle broke into pieces while removing it, even though I used a 1.5" PVC pipe against a rubber floor mat. It broke before the O-rings got to the snap ring groove.

I "shaved" the O-rings on both ends putting the motor together. I took it apart and replaced them. Greased the heck out of the snap ring grooves and shaved them too. (they held).

The forward snap ring broke in half when I tried to remove it. and then broke again while fishing out one of the halves. I've never had a snap ring brake.

Now out to the lathe......

Tony
 
The nozzle issue is wierd. I have had that happen on 54mm and 38mm Kosdon nozzle, as well as the shaved O ring issue in K cases.

What was the performance of the beastie?
 
Just looking at the test flight data..

RC3 16055 agl 1549 mph
Raven 15948 agl 1411 ft sec

The below blurry shot is the best I've got. The rocket is up the rail about a foot. It sort of looks like the rockets on fire. It's not. That's just the Swamp Gas formula.
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all splayed out on the playa. Dual deployment with a reffed chute.
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The motor for Balls looks like..
the case is 36" long 33.3" of propellant (Swamp Gas) 4433 n/S 4.6 sec 73% L960 phenolic nozzle.

I think I'll need to use my high altitude vinyl charge holders for this flight.

Tony
 
here's the finished Balls motor...

36935480820_7110ec2f9f_z.jpg


The nozzle is a turned down used CTI 76mm phenolic noz. I like using phenolic nozzles on long motors. I can design the motor to be progressive (long grains) and start it at it's chuffing point. This allows for a cushion at start up (erosive spike) and the motor never gets to be a progressive burn because the nozzle is eroding.

Tony
 
here's the finished Balls motor...

36935480820_7110ec2f9f_z.jpg


The nozzle is a turned down used CTI 76mm phenolic noz. I like using phenolic nozzles on long motors. I can design the motor to be progressive (long grains) and start it at it's chuffing point. This allows for a cushion at start up (erosive spike) and the motor never gets to be a progressive burn because the nozzle is eroding.

Tony

Awesome! Good luck with the longer swamp gasser flight!!!

Love the quick turn around time between flights!
 
I heard adding anything to the e-120 epoxy would weaken it? I have used it and left it the natural color.
 
I liked the 2.5" Kosdon motors. The M3700 was quite the ride minimum diameter.
I did with Frank a thin wall case, 1/16" with threaded closures. On the pad it weighed 16 lbs with 10lbs of propellant. The name of the rocket was "Sleeps With The Lizards".
M

Are you sure the 10 lb propellant weight figure is correct? For a 5200 Ns motor, that seems like a lot.
 
Are you sure the 10 lb propellant weight figure is correct? For a 5200 Ns motor, that seems like a lot.

Two different motors.
The thin wall in second sentence was longer and propellant OD larger than the 5200Ns motor from first sentence.

M

Added, best I can find in old poor records is about 60" of prop. M
 
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