Longest burn time commercial or EX amatuer motors?

[Rocketjunkie]

6" P motor, Bates grain, 8.3 sec burn, 74,000 N-s Got the makings for 2 more

 

[wclaybaugh2]

The wall temperature is a calculation from the residual byproducts measured.

I have not flown a pressure transducer fitted micrograin, but I have a thrust to pressure conversion formula that matches data from two groups in Europe that have directly measured pressures of 1800 psi. The ignition pressure pulse can be measured in 70 - 90ms after ignition at the bulkhead. The flame front lags behind the pressure front. I'm recording the highest thrust between 175 - 300 ms after ignition. After peak thrust, the rest is ZnS sublimation blowdown.

Replacing some of the zinc with aluminum does increase the Isp to 55-60 seconds.

The ability to measure micrograin parameters makes measuring APCP propellant characteristics a cake walk. 500 to 1000Hz resolution of flight performance parameters allows even the measurement of slag and unburned particles passing through the nozzle of current commercial motors.

The increasing cost of zinc dust will be the demise of micrograin.

Help me understand this….

Zinc plates out at 787 F and ZnS at 3360 F. Since the wall is unlikely to get as hot as the latter number, one should find ZnS on the wall, no? If there is Zn as well, then the wall didn’t get above 787F, no?

How do these materials on the wall allow a conclusion about burn rate?

Sorry, just confused here.

Bill

 

[MClark]

People sure put out a lot of effort to make really poor performance, dangerous to manufacture motors.

 

[jsdemar]

We've strayed from the original purpose of the thread... "longest burn time" to a dangerous topic of old micrograin fast-burn propellant. The Z/S discussion is taking place in the regular Propulsion forum but should be moved to the restricted Research forum, IMO. @cwbullet @tim cubbedge

 

[tim cubbedge]

Let’s keep on topic otherwise this thread will get moved to research forum.

 

[Spacedog49Krell]

Prediction: Within the next 5 years 20-40 second burn motors will become commercially available for launches at Spaceport America, Black Rock, FAR, and the MTA. Tripoli and NAR will develop special levels of certification for these launches due to the 30-100 km altitude safety requirements.

 

[AeroTech]

Prediction: Within the next 5 years 20-40 second burn motors will become commercially available for launches at Spaceport America, Black Rock, FAR, and the MTA. Tripoli and NAR will develop special levels of certification for these launches due to the 30-100 km altitude safety requirements.

20 second motors were commercially available in the ‘80s. 30-100 km flights are possible with motor combinations available now and in the near future. These are combinations totaling <40,960 N-sec, so still a “high-power” rocket by NFPA definition.

 

[3stoogesrocketry]

Evolutions whiplash . 40 seconds into the burn the liner failed.