MTA Firing Event, 2022-04-02

by Dave Nordling, President, Reaction Research Society


The RRS held a launch event at the Mojave Test Area on Saturday, 4/2/2022. Larry Hoffing was our pyrotechnic operator in charge. It was a very pleasant day with low winds for most of the day.

The sign arch welcomes people to the Mojave Test Area

It was also the first time in a long time that all four members of the executive council were present at the same event. We took the opportunity to capture the moment in a photograph.

The executive council for 2022; Keith Yoerg (secretary), Dave Nordling (president), Larry Hoffing (treasurer), Frank Miuccio (vice president)

The primary project for that day was the launch of 15 Baby Bertha rockets made by the students of Nickerson Gardens over the six-week educational program the society held with the support of LAPD CSP. The rockets give the students a tangible sense of accomplishment and seeing them in flight from the MTA gives them good memories of what hard work can do.

The newest armada of Baby Bertha’s ready for flight.
Students wait in the Dosa Building before the launch.
The launch rails made ready for the event.

There was an RRS standard alpha made for this occassion which flew at the end. It was prepared by our experienced pyro-op, Larry Hoffing, and made an impressive finish to this school event.

Larry Hoffing (right) trains his colleague in the assembly and loading of a micrograin alpha rocket.
Larry Hoffing oversees the launch rail with Keith Yoerg for an alpha launch.

Secondarily, we had a few members of the USC RPL team out at our site to begin repairs of the concrete pad area used in their static fire tests. Removal of the male anchor bolts in USC’s custom mounting pattern were finally distorted too much to be useful. They were a frequent tripping hazard and their removal was a blessing.

USC RPL cinducts repairs of the vertical test stand pad.
USC RPL team at work making improvements at the MTA.

Also, the USC RPL team made several contributions to improving the MTA site with earthwork, brush clearance, and just good old fashioned hard work. We’re grateful to them coming out to help keep the site in good shape,

Earthwork in progress to backfill the erosion.
View from the blockhouse of the Peregrine rocket ready for launch.

The last portion of the day was spent launching a few more model and high-power rockets before the winds became too high. We used the time to plan our next event and rearranged our materials in our new storage container.

Our next monthly meeting is Friday, April 8th. Contact the RRS secretary for information.

secretary@rrs.org –


MTA launch event, 2018-07-21

The Reaction Research Society (RRS) held a launch event at our private Mojave Test Area (MTA) on Saturday, July 21, 2018. As I came into the site in the morning, I snapped a picture our front gate and the rough location which will be the site of our new sign to arrive very soon.

Follow that car. Turn left to go to the RRS.

Jim Gross was our pyro-op for the event. Many of us arrived early so Jim and the rest of the RRS had time to review the projects we wanted to hot-fire and fly if possible that day. Also, it was new members’, Michael Lunny and Bill Behenna’s first trip to the MTA. I think there is no better way to sell our membership on the benefits of the RRS than your first trip to the MTA. It worked for me!

Jim Gross, our pyro-op for the day

We were glad to host another group of students from the Watts area schools with the support of the Los Angeles Police Department’s (LAPD) Community Safety Partnership (CSP). This has become known as the “Rockets in the Projects” program.

LAPD CSP on Facebook

It was a challenge to hold this event in July in the Mojave desert, but the kids and staff seemed to withstand the 100-degree heat quite well with lots of water and bringing ice. We gave our safety briefing to everyone and explained the do’s and don’t’s for the event. RRS member, Matt Tarditti, was there helping with getting people shuttled around to the places necessary including moving our pyro-op, Jim, and his apprentice, (me) Dave Nordling, back and forth between the bunker and the alpha launch rails. Every step adds up in the heat and it’s wise to work as efficiently as you can. The heat ultimately got to me and I had to take a pause into the air conditioning of my truck. Despite my best efforts in hydration, the Mojave summer was still overwhelming. It is a feeling that many RRS members know all too well at some point in their time with the society at the MTA.

Matt was kind of enough to continue to assist Jim to complete the launch series with the alphas. Even, Jim Gross, who has been a resident of the high desert for many years, was having a tough time in the high temperatures and very low winds of that day. We had extremely low winds which made for great rocket launching weather, however with the building clouds above holding in a lot of the heat of the day, it was a real challenge for everyone to fight the stifling heat. The RRS conducts launch and test events at the MTA year-round, but some months are harder than others.

Matt Tarditti and Jim Gross under the hot July sun at the MTA

The LAPD CSP team does a great job in preparing these kids in the weeks ahead before this event. Often, this is many of the kids’ first trip into the Mojave desert. The stark beauty of the landscape hides the subtle dangers of snakes, spiders and the ever-present risk of heat stroke (even at 10:00 AM!). The RRS educational program is both fun and informative and through preparation everyone can make things safe. The kids were quite ready for the final event in the RRS educational program which is seeing their painted and assembled RRS standard alpha rockets take flight.

Michael Lunny, Frank Miuccio and Larry Hoffing stand among the students during the safety briefing at the George Dosa building

Our first goal of the event was to get the students’ rockets in the air so that those less experienced in the desert heat can go on home once the last one was complete. We had seven standard alphas to be launched, all painted by the students as their way to personalize their team’s flight. As always, the RRS reminds our classes that painting the bodies is nice, but since they return to the ground without a parachute, painting the fins in a bright and observable color matters the most when trying to find them on the desert floor. You’ll only have the tail fins sticking out of the ground when you find your rocket.

Seven alphas in the rack from Watts, plus Larry’s customized alpha with the wires sticking out of the payload tube

The kids paid careful attention to the time of flight which gives some data as to how well packed the alphas were. Two stopwatch measurements were made on each of the seven alpha flights. Impact was not heard on the seventh flight, so no data was taken. The results are somewhat consistent between the two readings and ranged between 36 and 39 seconds.

Time of flight measurements on six of the seven alphas flown on 07-21-2018

Ideal time of flight for an RRS standard alpha is thought to be between 35 and 42 seconds. This would indicate that Osvaldo’s rapid micrograin loading system is doing well to properly pack the propellant leading to good results.

Still shot from Michael Lunny’s video of the RRS standard alpha taking off

After the sequential launch of all seven alphas, it was unanimously decided not to let the kids hunt for their rockets downrange. The LAPD CSP team and the Watts kids went home after taking a picture under our arched sign. RRS member, Michael Lunny, shot a great video of one of the alpha launches from the bunker. I hope to get it posted to the RRS YouTube channel. We have a few micrograin rocket flights on YouTube, but we hope to add more content there soon. You’ll notice our name is not fully spelled out due to the old character limit when the account was made.

ReactionResearchSoc

Reaction Research Society on YouTube

After the Rockets in the Projects, this left the rest of the RRS membership to attempt the other projects we had ready for this launch day.

Richard Garcia brought his home-built rocket that is adapted for the sugar-KNO3 motor he tested at the 2018-06-02 event. He made three motors, one as a simple end-burner, the other two were cored. The plan was to fire conduct a static firing or two with his test motors and if all looked good fly the third motor in the rocket from the RRS rail launcher. “Rocket candy” as it is also called in amateur rocketry has been getting more popular at the RRS.

Richard Garcia stands in the assembly area by his golden rocket built for his custom sugar motor

Richard’s end-burner grain, 2018-07-21

Richard’s nozzle for his custom sugar motor

Richard’s two cored grains, sugar-KNO3 motors, 2018-07-21

Richard brought back his vertical static fire stand that bolts to the larger RRS frame. Although his thrust stand is not outfitted with a load cell (yet), it does give him the opportunity to safely secure his test motors and visually compare the results and time the burns.

Richard Garcia’s sugar motor held down to his vertical thrust stand for static fire

Larry Hoffing made a parachute system in his RRS standard alpha. His system was a little different from Osvaldo’s as he required a second firing line to light a delayed fuse for the parachute deployment system he put in. His son, Max, was there to help get things ready for flight as we included Larry and Osvaldo’s alphas into the launch sequence. Larry’s goal was to explore an older method of timing the deployment of his parachute by use of cannon fuse.

Larry’s alpha payload system being made ready for flight, 2018-07-21

Also, Larry had attached a signalling whistle on one of the fins. The ancient Chinese used to mount whistles on their rockets of war to strike fear in the hearts of their enemies as the rockets would scream to their target. It was Larry’s intent to add the element of sound not only for an impressive screeching launch off the rails, but also for better tracking of the rocket’s final descent to the ground. Although having a single whistle mounted to just one fin will impart a spin to the alpha, the flight will still be stable as proven on similar alpha flights. In the recent past, we have had success flying a larger, single keychain camera on the outside of a single fin while maintaining good flight stability despite the nauseating rapid spin seen in the footage from these externally mounted cameras.

Larry’s alpha with a whistle mechanically fastened to a single fin, 2018-07-21

Osvaldo inspects Larry’s alpha rocket in the launch rails with the second firing line connected for the fused payload timer

Unfortunately, Larry’s alpha had a problem at launch with the failure to light the micrograin rocket. Also, with this delay it was apparent that the parachute payload deployed way too early. The goal was to fire at 20 seconds in the flight and the fuse seemed to go at only 2 seconds popping the payload tube while the rocket stayed on the alpha rack. The two systems had to fire at nearly the same time but one system failed entirely and other went off too early.

After exploring all other failure modes with the firing circuit and procedures, it was confirmed that it was a bad electric match with a break in the wire. This was the first time I’ve seen an electric match fail in the three years I’ve been with the RRS, but it has been known to happen. With Larry’s whole payload system requiring repackaging, it was decided for expediency, just to remove Larry’s rocket from the launch rails, remove the nozzle and dump the micrograin propellant for a safe disposal burn on the ground. Larry will be able to re-use his alpha hardware, but it will have to wait for next launch.

Next was Osvaldo’s red colored alpha with his alpha with a parachute system built in it. Osvaldo made some minor improvements to the circuitry and this was to be his second flight. He also had a commercial telemetry package within his payload section.

Osvaldo’s red alpha with the breakwire switch to start the timer and the pull pin to arm the battery before walking away to the bunker to fire

Osvaldo’s alpha parachute system, break-wire secured to launch rail starts the internal timer

The first flight of his original parachute design for the alpha on 2018-06-02 was a complete success. Despite some slight overheating of the parachute from the black powder deployment charge on the initial flight, the rocket still coasted down very gently such that it laid neatly on the ground and a shovel wasn’t necessary for recovery.

The flight of Osvaldo’s second alpha was similarly successful in that the break-wire system and deployment mechanism operated properly, but the parachute itself failed to unfold due to tangling. The rocket’s descent even with the folded parachute was able to be spotted and Osvaldo recovered all pieces of his second flight.

Osvaldo inspects the second iteration of his alpha parachute system, 2018-07-21

Also, as an added bonus, Osvaldo was able to fit a commercial telemetry package to measure the flight acceleration. As the whole package survived in tact, it will be very interesting what the device was able to measure from within the tight confines of alpha payload tube near the nose. I hope he can present his results from the flight at the next meeting.

Osvaldo’s data package survives the flight, a little singed, and despite a folded parachute

There has been a lot of great progress in parachutes for the RRS standard alpha recently. Both Larry and Osvaldo have made great progress. With the persistent efforts of our RRS membership, I think its reasonable to expect that we could offer a standard alpha parachute package for our future events once we demonstrate a series of successful flights, settle on the design and figure the added cost.

Richard Garcia’s project having two successful static firings gave him confidence to try to mount and fly the third sugar motor. After having some initial integration problems and a rail button coming off, he was able to get his golden rocket ready for a launch on the rail launcher.

The rail launcher at the MTA is a great asset to the society. It has been used on several projects with good success, but it is a very heavy and sturdy device that requires two or three people to assemble and make ready. Also, the pin system that connects the rail to the stand fits very snugly and sometimes requires a lot of elbow grease and persuasion (perhaps with a rubber mallet) to get the right alignment of the holes. Despite the high heat, we managed to get things ready for Richard’s flight.

Rail piece with 12-foot, 80-20, 1515 aluminum rail

Launch rail base

Launch rail system ready to receive the rocket

Underslung launch rail system at the RRS MTA, assembled and ready for Richard’s flight, 2018-07-21

80-20 aluminum 1515 sized rail (1.5-inch) used as the guide for the launcher

Richard checks the manual for the telemetry package that he armed for flight.

Richard’s flight was on one hand a little underwhelming as his sugar motor did not produce a great deal of impulse, but it did manage to propel itself up and get clear of the launch rail before neatly turning back to the ground in a low-speed, but very steady and stable flight. Although his rocket only made it 50 feet downrange, it can be seen in the flight video that his rocket was stable throughout the whole low speed which is a testament to Richard’s good construction of a very aerodynamic and well-balanced vehicle.

The sugar motor doesn’t offer much impulse as it burns out shortly after clearing the launch rail

The rocket gently pitches over after burnout heading for the ground not very far downrange (the last good frame I have from my camera-phone)

After a perfect arc at its low apogee, the rocket turned back to the ground and landed almost perfectly on its nose. Despite the rough landing, the nosecone wasn’t damaged and many parts of the vehicle were similarly undamaged.

A very short, but extremely stable flight off the rails for Richard’s golden rocket with a custom sugar motor

Richard safes his payload system as he inspects the recovered rocket.

Richard will be working on increasing the impulse from his motor, but he can be very confident in his vehicle design. With a little rework on some of the parts, I think he should have a very impressive flight at the next launch event.

Osvaldo has put a lot of work into the horizontal thrust stand that I started. To be able to static fire an alpha rocket to measure the impulse, we have to accomplish two more things.

RRS horizontal thrust stand in need of an extension piece to stabilize an alpha for static fire

The first is to get better mechanical support for an RRS standard alpha to prevent sideways motions or “wagging” during firing. The stout, welded frame of the horizontal thrust stand fits just fine to the concrete slab foundation and is very secure, but the 3-foot length of an alpha could create quite a wicked angular load on the load cell. After Osvaldo and I had discussed a few design concepts, Osvaldo brought his design to the MTA. Given the time constraints of the launch events that came before and the stifling heat, we had no time to attempt a fit check of an alpha rocket in the thrust stand. The complete assembly will have to be fit checked at the next event. Osvaldo had also noticed that when the long alpha rocket is put into this short stand, the rocket doesn’t align very well with the beam. Some minor adjustments might be necessary to make sure the thrust vector is properly aligned with the axis through the load cell.

RRS horizontal thrust stand extension piece

The second thing is to try to calibrate the load cell to make sure the S-type load cell is still reasonably within its original factory calibration. Osvaldo brought in a home-built frame with a hydraulic jack and pressure gauge which can reasonably approximate a force by the pressure and piston area relationship. We didn’t have time to try this setup, but this device can be demonstrated at home if Osvaldo has time before the August 10th meeting.

hydraulic jack testing rig for verifying the S-type load cell calibration

hydraulic jack-based force tester with high pressure gauge attached

The horizontal thrust stand was not ready for the 2018-07-21 launch event due to a lack of cabling and a hardy computer to manage the data acquisition. Many of us are reluctant to bring our personal laptops to run the data acquisition in the abrasive sandy dry lake environment at the MTA. Chris Lujan at the July meeting talked about using a simple Arduino Raspberry Pi computer as a low-cost alternative to gathering and processing the data. Hopefully, the RRS will get a simple device for this purpose and have it programmed to take data from the load cell as we conduct our hot-fires from this horizontal thrust stand. There still is a lot of work to do in getting the horizontal thrust stand working. With more hard work, the RRS will have this project working soon, hopefully by the next launch event in the fall. We’ll post updates as this project advances.

One final note on the event is that the RRS will be posting a few things on Instagram once the secretary (me) has time to get things started. The RRS is brand new to Instagram so we hope to expand our presence here to better show everyone what we do. At first, the RRS executive council will have access to post photos at the events we attend for the RRS. We hope this presence on Instagram will generate more excitement and participation at events with the RRS.

Follow RRS on Instagram

The RRS will certainly discuss today’s launch event as a whole at the next meeting on Friday, August 10, 2018. There were a lot of great things we tried at the event, but there were also a lot of logistical things we can do better next time. Also, it would be a good time to review some of the material improvements that we ought to make at the MTA to better handle the projects we expect in the near future.

Please join us on August 10th!

MTA launch event, 2018-06-07

The RRS held another smaller launch event at our private testing facility (MTA) in the Mojave desert on Thursday, June 7, 2018. This was a special event for the RRS members from the former Chaminade High School Rocketry group led by Jack Oswald. They have been working hard on their solid motor design. After a successful test series on a single 6-inch Bates grain, they moved up to a vehicle sized test with multiple six-inch grain modules installed. Dave Crisalli and Osvaldo Tarditti were available to assist in the loading and installation process making ready for testing. The vehicle static fire test was oriented nozzle up with a load cell at the bottom of the frame secured to the vertical test stand at the RRS MTA.

The static fire testing was for a 10,000 lbf-sec flight motor. The motor was expected to perform at 1500 psi, produce over 2+ tons (>4000 lbf) of peak thrust, and burn its 43 lbs of composite BATES grains in approximately 3 seconds.

Osvaldo had video of the firing where we got the still photos below. Osvaldo will bring the video footage to the meeting tomorrow on Friday, 6/8/2018, where everyone can see what may have happened.

Vertical static fire of a solid rocket motor at the RRS MTA, 06-07-2018

The solid motor started okay. The nozzle plume looked good for the first few moments.

Jack’s motor starts off just fine. A nice nozzle plume is evident.

Unfortunately, shortly after start, about 2 seconds into the burn, the pressure climbed substantially to 2300 psi causing a nozzle failure and subsequent burnout.

It looked like something disturbed the flow in the frame just before the huge fireball and the disintegration of the nozzle

After the nozzle failure, the solid motor spews chunks of fiery propellant until it fully burned out.

In the coming months, Jack’s team will make another motor reducing the Kn factor and significantly reinforcing the nozzle design to carry through with their plans of launching a boosted dart to an altitude of 150,000 feet sometime this year. This is still an impressive accomplishment and with some perseverance, success will come. More details to come as things proceed.

During the June 7th event, Osvaldo took some time to search down-range for rockets with his extractor tool. As luck would have it, he found one of the RRS standard beta rockets launched by UCLA in 2017. It was found about 3000 feet downrange which isn’t terribly far away. The winds must have been very favorable to allow the beta to plant itself much closer to the launch site. From the photo, you can see that this RRS beta had a fin-can type of fixture at the tail which is easier to manufacture.

Beta planted 3000 feet downrange from the launch rails, straight west more or less

The convenience of pulling the rocket straight from the ground with the manual winch is tremendous, but the method often shears off the payload tube in the hole. Shoveling does have the advantage of removing most if not all of the parts if one is inclined to spend the hours necessary to dig four feet below the surface. The payload tube from the beta unfortunately was not extracted with the propellant tube. Osvaldo will bring the beta to show everyone at the meeting tomorrow.

Osvaldo lifts the beta rocket from out of the desert floor

We’ll have our monthly meeting (every 2nd Friday of the month) on June 8th at 7:30PM sharp. Please stop in!