Rocketry Planet

We are very pleased to announce two new certified motors from RATTworks, Dave Griffith, head gas passer.  The following motors are the first in a new technology of hybrid style motors developed by Mr. Griffith and authorized by the NFPA policy document 1125, 2007 edition. 

In the top picture, a K-350 Tribrid is ready for a static test, while the bottom photo shows a K-600 Tribrid doing a manufacturer demo.

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These motors are called Tribrids, specifically for their ability to use both a nitrous oxide oxidizer, solid ABS grains, and now certified for the first time, liquid alcohol as fuels. 

Both of these motors are in RATTworks standard 2.5" (64 MM) case diameter, are of the K class, and once assembled, are no different from any other Urbanski/Colburn Monotube hybrid motor in external profile.

The K350TR-P is a 45% K motor, 1861 total NS, 853 NS max (at the start of the Tri-propellant mode), a 463 N average and a 3.89 second burn time. The thrust profile is a typical hybrid profile, albeit with an atypical difference in the initial rise to about 120 pounds for about .1 seconds, then a transition to the Tribrid phase (alcohol introduction) for a second rise to 175 pounds. From there it is straight line regressive to the 3 second point and 100 pounds, where it enters vapor phase, dropping to 40 pounds. It then does a typical hybrid tail-off to zero at the 4.6 second point. The motor total weight (pre-nitrous) is 5.3 pounds with 290 ml alcohol (.645 lbs.), .115 lbs ABS grain weight, and 1170 cc of nitrous oxide capacity. Post weight is 4.54 lbs.

The K600TR-P is a 70% K motor, a slightly longer and different (larger bore) injector version of the K350TR-P motor. It has 2170 total NS, 1223 NS max, a 561 N average and a 3.67 second burn time. The thrust profile is again a typical hybrid profile, the initial rise to about 170 pounds for about .1 seconds, then a transition to the Tribrid phase (alcohol introduction) for a second rise to 250 pounds. From there it is straight line regressive to the 2.2 second point and 150 pounds, where it enters vapor phase, dropping to 50 pounds. It then does a typical hybrid tail-off to zero at the 4.6 second point. The motor total weight (pre nitrous) is 6.55 pounds with 370 ml alcohol (.82 lbs.), .21 lbs ABS grain weight, and 1476 cc of nitrous oxide capacity. Post weight is 5.52 lbs.

Congratulations to Dave Griffith and his development team for bringing this new technology to the membership and we wish them great success.

Paul Holmes
Chairman, Tripoli Motor Testing

Reader comments:

#1 Re: Article: TMT certifies new tribrid technology from RATTworks

Wow! It finally has happen. I have been waiting 8 years for this. A motor that runs on moonshine.

How is this going to fit into NFPA 1127. While it's a certified motor, flying it violates the safety code. It seems like a huge fire risk flying this anywhere outside of a dry lake bed.

Bayourat on 05-18-2010 10:44 AM

#2 Re: Article: TMT certifies new tribrid technology from RATTworks

Quote:

It seems like a huge fire risk flying this anywhere outside of a dry lake bed.

In what way?

billspad on 05-18-2010 12:25 PM

#3 Re: Article: TMT certifies new tribrid technology from RATTworks

Quote:

In what way?

ever heard of a cato?

Terry Dean

shockwaveriderz on 05-18-2010 01:16 PM

#4 Re: Article: TMT certifies new tribrid technology from RATTworks

The two sizes of motor (small K and large K) use 290 ml and 370 ml of alcohol respectively. That doesn't seem like very much to me (370 ml is a little over 12 oz) but I don't know how NFPA formulated the cleared-area requirements.

mcaplinger on 05-18-2010 01:46 PM

#5 Re: Article: TMT certifies new tribrid technology from RATTworks

How would a Ratt CATO be different from any other CATO? Almost any CATO, regardless of the propellant type, is likely to spew a burning substance.

PJStein on 05-18-2010 04:41 PM

#6 Re: Article: TMT certifies new tribrid technology from RATTworks

We just lost a great place to fly in Wayside TX. I don't think it was a Tribrid Hybrid Motor??
Gary

TFRLLC on 05-18-2010 07:46 PM

#7 Re: Article: TMT certifies new tribrid technology from RATTworks

Quote:

Wow! It finally has happen. I have been waiting 8 years for this. A motor that runs on moonshine.

How is this going to fit into NFPA 1127. While it's a certified motor, flying it violates the safety code. It seems like a huge fire risk flying this anywhere outside of a dry lake bed.

I'm lost - how is this a bigger risk than other motors? I saw the CATO comment but I don't see how this CATO would be more dangerous than any other from a fire perspective. I'm also very confused about what part of it violates the safety code - I'm not saying you are wrong but I am not following it so far.

UncleVanya on 05-18-2010 10:41 PM

#8 Re: Article: TMT certifies new tribrid technology from RATTworks

Quote:

ever heard of a cato?

Terry Dean

Yes but the implication was that this motor is more of a fire hazard than a solid or conventional hybrid. The only difference is the alcohol and someone on the TRA mailing list pointed out that the alcohol has less of a chance of making it to the ground on fire than a chunk of propellant.

billspad on 05-18-2010 11:17 PM

#9 Re: Article: TMT certifies new tribrid technology from RATTworks

Quote:

Yes but the implication was that this motor is more of a fire hazard than a solid or conventional hybrid. The only difference is the alcohol and someone on the TRA mailing list pointed out that the alcohol has less of a chance of making it to the ground on fire than a chunk of propellant.

Most solid propellant self-extinguishes upon sudden depressurization of the motor. I've never seen solid chunks burning on the ground after a cato.

If the casing cracks slightly and the motor is still under pressure, then there's a fire hazard, especially if the rocket leaves the pad and hits the ground because of the poor thrust due to the failure.

I could imagine that a tribrid might be more flammable if it power-pranged, causing a sudden mixture of burning liquid fuel and oxidizer. But, it might not be any more likely than a hybrid or solid.

-John

jsdemar on 05-19-2010 01:19 AM

#10 Re: Article: TMT certifies new tribrid technology from RATTworks

The possibility of any added fire hazards were just discussed on the TRA List Forum, where Paul Holmes and I added some comments. Two factors play against any higher risk of fire caused by the alcohol - one is that the amount used is very small, and another is that with a cato, the alcohol is going to be consumed and/or vaporized pretty quickly. This isn't just theory, because there were some failures early in the development/demo program, and no additional fire hazards were observed.

Ken Good

KJGood on 05-19-2010 08:32 AM

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