MTA launch, 2019-04-06

Dave Nordling, Secretary, RRS.ORG

The Reaction Research Society (RRS) had another launch event at the Mojave Test Area (MTA). We had a nice cool day for the launch with a little wind. The winter seasonal rains left the land green which was a lovely change to the usual desert brown.

The RRS sign welcomes our guests to the MTA. The winter seasonal rains had turned the land green.
Desert flora in bloom downrange of the RRS MTA

We were pleased to be joined by California State Fire Marshal, Ramiro Rodriguez, who came out to see our amateur rocketry group in action. David Crisalli was our pyro-op for the event and I was glad to apprentice under him once again for this event.

RRS events coordinator, Larry Hoffing; RRS member and pyro-op, Dave Crisalli, California State Fire Marshal, Ramiro Rodriguez; and RRS secretary, Dave Nordling

Also joining us was the students at University of Southern California’s Rocket Propulsion Laboratory (USC RPL). The students had prepared a 6-inch solid motor for static fire test. They were demonstrating an improved carbon-phenolic nozzle design. They arrived the night before and made preparations all morning.

The name of USC’s 6-inch solid motor was “Poise”

USC still had a few more steps to go in their preparations before our other guests from Compton Elementary arrived. LAPD CSP and the RRS were glad to bring another class of young minds to see firsthand a rocket in flight. After all had arrived and settled, we held our safety briefing with our pyro-op, Dave Crisalli.

Students, LAPD officers, USC and the RRS gather in front of the George Dosa building for the safety briefing.
Ramiro relates practical advise on safety to the students of USC RPL.
Everyone safe in the observation bunker. We’re ready to launch.

We had six of our standard alphas made by the kids at Compton Elementary. This launch event is the final day in the educational sessions we do with local schools thanks to our partnership with the LAPD CSP.

5 of the 6 alphas sit in the rack; Osvaldo’s alpha with a parachute sits to the left.

We loaded each of the rockets in the numerical order they were labelled. Each team had their own color scheme to help make them unique. Reds and blues stand out well against the desert browns and green of the brush.

A very well timed shot of an RRS alpha just clearing the box rails.
A not-so well timed shot just a split-second too slow on the shutter.

After the last alpha from Compton Elementary, we launched Osvaldo’s alpha with a parachute recovery system packed in the payload tube. The parachute deployment system has a simple timer circuit that starts when a pin is pulled as the rocket speeds away off the rails. The red flagged plug in the photo is the safety pin to prevent accidental activation of the payload.

Osvaldo’s customized alpha rocket with a parachute recovery system (left in the photo).

Unfortunately, the parachute system didn’t deploy after launch. It’s possible that the timer deployed the parachute too early which the forward pressure against the payload tube may have held the system in place. The other possibility is the timer didn’t start at all. Either way, the recovery of Osvaldo’s rocket had to be done like all the others… with a shovel.

After the last of the alphas fired, LAPD CSP packed up Compton Elementary for the long ride home. The RRS is grateful for the chance to show young people the excitement of rocketry in the Mojave desert.

Dave Crisalli talks wtih USC as they made their solid motor ready for static fire. USC had several cameras ready to record the 11 second firing.
Dave oversees the careful installation of the igniter system into the core of the solid motor.

The USC RPL team was ready after waiting through our fusillade of micrograin alphas. With final preparations made and instrumentation checking out, the installation of the igniter package on the end of a long sacrificial stick was inserted to the proper depth. Standing back and bringing everyone to safety, USC began their countdown.

Still capture from video taken from the RRS MTA blockhouse. The motor ran full duration.
Post hot-fire inspection showed the carbon-phenolic nozzle still in tact.

USC had predicted a peak thrust of 800 lbf and a burn duration of 11 seconds. Actual burn time matched predictions, but thrust levels may have been short of expectations. USC was crunching the data as the RRS moved on to recovery of the alphas from down-range.

We were fortunate to find three of the alphas from the launch event. They were found north-west of the launch site which was unexpected. Another alpha from last year’s event was also found.

One of the three alphas we recovered later in the afternoon.

Osvaldo’s ratcheting extractor tool came in handy once again to avoid the back-breaking work of shoveling out an alpha once it’s found.

Securing the chain links in a circle near the nozzle throat gives the steel cable something to grasp as the ratchet progressively pulls the rocket from the ground in the same direction it entered.
Osvaldo’s alpha with a parachute was one of the alphas we recovered. Sadly, the parachute system did not deploy and the alpha returned ballistically with the parachute still packed inside.

The next RRS meeting will be Friday, April 12th, at the Ken Nakaoka Community Center in Gardena. This will be our last meeting before the 2019 RRS symposium on Saturday, April 27th. We’ll have more information posted here on RRS.ORG very soon.

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