MTA launch event, 2018-10-27

The Reaction Research Society (RRS) held another launch event at our private testing site, the Mojave Test Area (MTA), on October 27, 2018. We had a really big day in hosting a launch event for Weigand Elementary School and supporting the projects of several of our members. This was one of the more perfect days for a launch. The day time temperatures stayed below 90 degrees Fahrenheit and the winds were nearly still the whole day.

Old Glory slowly waves in the light breeze of the cool late October morning in the Mojave Desert

Our pyro-op for the event was John Newman, of the Friends of Amateur Rocketry (FAR) group.

Friends of Amateur Rocketry – webpage

John allowed myself, Dave Nordling, and Larry Hoffing apprentice under him for the event as we are both in training to become licensed pyrotechnic operators in California.

John Newman (right) from Friends of Amateur Rocketry (FAR) talks with Mr. Oswald (left) and Dr. Kasparian (middle) at the RRS MTA, 10/27/2018

John Newman (left, behind the wall) and Larry Hoffing (right) oversee the loading of micrograin propellant at the RRS MTA

The RRS welcomed Weigand Elementary School and the Los Angeles Police Department’s (LAPD) Community Service Program (CSP). They had just finished the six session program and had ten (10) alphas ready to launch.

Frank Miuccio shows one of the two RRS blockhouses to the students of Weigand Elementary School

RRS member, Michael Lunny, had come out to the MTA the week before to help Osvaldo with mixing of the micrograin propellant. The simple mixture of zinc and sulfur powders is relatively safe, but requires time to properly mix and load. With the larger demand for alpha rockets with school projects and our growing membership, it’s no longer a process that can be done in the early morning hours before launch day.

Osvaldo Tarditti and Michael Lunny at the RRS MTA, 10/27/2018, having done the hard work of loading the rockets the week before

The ten alphas from Weigand Elementary and Michael Lunny’s alpha in white, all loaded, tagged and ready to go

RRS member Alastair Martin was at our event doing a great job in video-recording many aspects of our event. Alastair and Bill Janczewski, both newly elected to the position of Media Coordinator at the RRS, have been helping expand the presence of the RRS in social media and to the public at large.

Alastair Martin, armed and ready, in the RRS MTA blockhouse

Alastair gets his camera ready for the next alpha launch

Alastair got a lot of great shots and video-footage which I’ll share as they come in. Some of the short videos and photos from the 2018-10-27 event are already posted on the RRS Instagram page.

Follow the RRS on Instagram – ReactionResearchSociety

Just before the briefing, two of our new members had the chance to experience loading their own alpha rockets with the micrograin propellant. Xavier Marshall and Wilbur Owens were coached in the process and got a first-hand feel for classic micrograin rocketry. Michael Lunny’s alpha rocket was already set to go the week before when he helped Osvaldo load the ten alphas for Weigand Elementary.

Wilbur Owens loads his alpha rocket, one cupful at a time, gently bouncing out the air pockets as he goes

Once the alpha propellant tube is full of propellant up to the bolt holes, Xavier Marshall prepares to install his nozzle with the electric match and burst disk which retains the powdered propellant inside

A close-up view of the alpha nozzle with its plastic burst-disk and electric match resting on the interior side, the electric match wires protrude out the bottom (held back by carpenter’s tape just for convenience)

[SAFETY BRIEFING]

We conducted our safety briefing at the beginning of the event before all present. We discussed the many natural and man-made hazards to help everyone become aware and be more safe. John Newman made us aware of a native species of snake, the Mojave Green Rattlesnake, which is sometimes known to become aggressive when discovered. The Wikipedia page is linked below.

the Mojave green rattlesnake

Mojave Green Rattlesnake – Wikipedia

Frank also reminded everyone about keeping their distance from the Desert Tortoise, which is a federally protected species that is also indigenous to the Mojave desert and the MTA. It isn’t very common to see these animals during the height of the day, but everyone needs to be aware and take heed of their surroundings to protect themselves and the environment.

The federally protected Desert Tortoise

Desert Tortoise – Wikipedia page

Besides avoiding heat exhaustion and spiders, collecting and properly disposing of trash, and maintaining their hydration, all attendees must remain under the cover of our reinforced bunker during hazardous operations. With the conclusion of the briefing, we proceeded to a propellant demonstration to show the combustion process on a sample of composite propellant and micrograin powder.

Small sample of composite grain propellant burns hot enough to cut through the steel case supporting it, slow burning but very potent

The bright yellow plume of burning micrograin propellant, zinc and sulfur together go up pretty fast

The next step was getting everyone into the bunker, while John Newman conducted the event as our pyro-op. Larry and I were on hand to assist in the loading and readiness for firing. The RRS alpha had a steel box frame launcher which is our preferred method of guiding these speedy metal rockets up and downrange west.

We got started loading them into the rack by the numbers. The kids did a great job of painting them and making them their own. Most importantly, they label them with large numbers. The color of the fins matter the most since that is the only part left sticking out of the ground at the end of flight.

First of ten alphas right at liftoff

Same rocket just a few frames later

After launching all ten of the rockets, we all took our lunch break. The day was very pleasant, but we all enjoyed a little bit of shade. After lunch, LAPD CSP packed everyone up for the long drive to Los Angeles.

Frank talks with the kids of Weigand Elementary after having lunch after a great launch

[MEMBER PROJECTS]

We started working on membership projects starting with launching Michael’s alpha. It’s always rewarding to launch your first alpha and it’s an experience that never gets old. It’s usually one in a series to come. Big thanks to Michael for helping the society get ready for the event.

Xavier Marshall tried a new approach to launch by allowing me to use the fly-away railguide that I had customized for the 1.25″ RRS alpha propellant tube. Additive Aerospace makes many standard models which this one was derived from the 38 mm design.

Additive Aerospace – fly-away rail guides

Xavier Marshall’s RRS alpha clamped into the launch rails

Flyaway railguide clamped around an RRS alpha

Xavier Marshall inspects his first alpha as it sits on the rail

The first rail launch of an RRS standard alpha was successful. The flyaway railguide seemed to hold as the micrograin rocket sped off the rails. We took video from the facing side of the rail to get a better look at the operation. I was able to get one good still from my camera phone video from the blockhouse. You can see the railguide just above the fins as the rocket has cleared the rails so the flyaway railguide has sprung open and now is free to tumble away.

Xavier’s rail launched alpha rocket makes a clean path up the 20-foot guide, rail guide still seen near the rocket just after clearing the rail

The railguide fit to the alpha very well but the rail buttons were a little sticky as the rocket was slipped into place. I think the dusty aluminum rail is more to blame for this. The workmanship on these flyaway railguides from Additive Aerospace is quite good. Flying one of these devices with a micrograin rocket was expected to be challenging given the high acceleration that micrograin rockets are known for.

The railguide was not recovered intact. I recovered most of the pieces and the plastic end pieces showed fractures. It’s not clear if the railguide broke on the ground from the fall, but given the spread of the pieces, it could be possible the sudden acceleration of the RRS alpha fractured the lower clamp as the rocket took off. Review of Alastair’s video in slow motion may answer what the failure mode is. All pieces were recovered within 50 feet of the rail.

The recovered pieces of the flyaway rail guide. A successful launch but the mechanism didn’t survive for more than one attempt.

Jack Oswald and his team had a set of sample end-burner motors with their next batch of propellant for burn-rate testing. After setting up the first motor, a key part was missing and the pressure transducer had to be mounted too close to the exit plume. It was expected that the pressure transducer wouldn’t survive the first burn but the test was expected to take good data. The test was executed, but unfortunately the test over-pressurized due to the grain separating from its liner during the initial startup. A lot was learned but the other motors were not able to be tested.

Jack Oswald inspects his test motors as he moves them to safe storage before test

Jack’s BEM test starts out okay. A leakage stream is seen coming out the side.

Just a second later, Jack’s test rig overpressurizes and the nozzle plate pops off

My last photo taken of that day was the last of the three member alphas sitting in the box rails ready to go. Wilbur Owens had the honor of flying his first alpha rocket at sunset.

Wilbur Owens takes a picture of his first alpha ready to fly away

The sun setting at the RRS MTA, Wilbur Owens’ first alpha rocket sits ready to fly out of the rails

With the last of our thirteen alphas flying out, we proceeded with the first firing of the horizontal thrust stand built to test loaded alpha propellant tubes. Osvaldo made some modifications to my stout steel frame adapted to the concrete slab in front of the old RRS blockhouse. Dave Crisalli poured this concrete slab as a working platform in the 1970’s. USC in recent times drilled the slab with 1/2″ female anchor bolts to test small 50-lbf motors. It made sense to use this existing foundation for our horizontal thrust stand.

Matteo Tarditti installs the completed RRS horizontal thrust stand to the concrete slab

Osvaldo uses his 185 lbf son, Matteo, as a quick load cell calibration check as Jack Oswald observes the 1124-lbf ranged load cell output on the laptop in the blockhouse. Awkward, but effective.

After some initial software and operator problems with getting and keeping the S-type load cell calibrated, the system was ready to go.

It has been MANY years since the RRS had made direct impulse measurements of an RRS alpha micrograin rocket, but we felt this hardware would be useful for other similar projects in our near future. Although horizontal testing of a micrograin rocket is not indicative of the actual vertical flight, we felt we could still learn much from this testing.

A simple bottle jack (commonly used for changing an automobile tire) was used as a load cell calibration device (pressure gauge was damaged in handling)

We retreated to the blockhouse and got the testing underway. After two false starts from the bunker, we got the alpha motor to fire in the horizontal position and captured it on video.

The results were good in that the load cell readings were captured and the structure adequately retained the rocket in its very brief (0.4 second) thrust bit. Osvaldo crunched the numbers from the readings we got from the test. Load cell readings indicated we reached a peak thrust of 544 lbf. Burn time was only 0.4 seconds.

This is the raw data from the alpha firing in the (translating) horizontal thrust stand; we need more data

Results from the alpha static firing on 2018-10-27

The RRS is very grateful to Interface Force Inc. of Arizona for their generous donation of the S-type load cell we’re using.

www.interfaceforce.com

An S-type load cell, made by Interface Force Inc.

These devices are not very expensive ($350?? each) and are available in sizes from just 100 lbf to up to several thousand pounds. Button cells are more compact and also work well, but they tend to be more expensive.

The big surprise was that our concrete pad wasn’t as well secured as we had hoped. The pad was only 6 inches thick which means that the slab was only an inch or so beneath the surface. I do recall being told this slab poured by RRS member, Dave Crisalli, in the 1970’s, was only intended to be a working surface and that it wasn’t very deep. USC in recent times had drilled the pad with 1/2″ female anchor bolts for a small 50-lbf.

The concrete slab held fast initially, but suddenly broke free displacing itself by over half its length.

Another observation was that we get a little bit of gas leakage at the end of the burn at the bulkhead. This has been seen in other alpha flight videos and thus it wasn’t a surprise.

Despite the moving target of the whole stand moving, just after the alpha fires, you can see gas leakage at the bulkhead

Osvaldo did not see any damage to the seals when we disassembled the rocket from the stand. This may be a weakness of the seal design but it doesn’t seem to harm performance. More experimentation will shed light on this.

Check out the RRS Instagram page to see this footage. I’ll be uploading it to our YouTube page soon as Instagram has a 60-second time limit for video.

While we were conducting test operations at the MTA, Wilbur Owens located his rocket downrange and started the laborious process of alpha recovery by shovel. Osvaldo’s extractor tool has made short work of this step, but I don’t know if it was available that day?

[PROPELLANT DISPOSAL OPERATIONS]

Jack and his team had a quantity of unspent composite propellant which had to be properly disposed. He had quite a bit from a failed attempt to cast a previous motor that hardened too quickly. The RRS MTA is a good place to do this. With the low winds, we are able to safely touch off the two batches in the waning hours of the day.

The first burn was the smaller of the two. The sun had already set so we were losing the light fast.

The first propellant disposal burn was a bit brighter than I thought but manageable.

With the light almost gone, the second batch lit up the night just for a brief moment before fading.

2nd propellant disposal burn starts off with the last of the daylight fading at the MTA

The second propellant disposal burn at its brightest, but quickly fades as the burn safely completes

[IN CONCLUSION … THINGS COMING UP]

Frank had said that the LAPD CSP is looking to start the next school program in January of 2019. We are very grateful to the LAPD CSP for their continuous support to our classes. The RRS is proud to help the community by sharing the hobby we love.

As mentioned in our last monthly meeting, the next event with the RRS will be our visit to Chapter 96 of the Experimental Aircraft Association (EAA). RRS members, Xavier Marshall and Wilbur Owens, invited the RRS membership to join them at their hangar at the Compton Airport on Saturday morning, November 3rd, at 10:00 AM. The RRS is interested in getting inexpensive shop space that is reasonably convenient to our membership residing in the Los Angeles area. The RRS is looking to help cultivate practical machining skills such as lathe work and milling. Many of our members already have these skills to some degree, but want to help other members become more adept at making their own nozzles, nosecones and other rocket parts.

The next RRS meeting will be November 9th at 7:30PM at the Ken Nakaoka Community Center in Gardena, California. We hope to have Jack Oswald and his team present their results. Despite the failure of the first and only sample hot-firing a great deal was learned which will make the next set of tests more likely to succeed.

A multi-staged vehicle with peak sensor

The following is a report written in February of 1985 by RRS members George Dosa and Frank Miuccio. The report details a three-stage rocket with several illustrations. For the sake of preservation, this report is reproduced in this article.

—- —-
A MULTI-STAGED VEHICLE WITH PEAK SENSOR
by Frank Miuccio and George Dosa

The purpose of this report is to document the building and testing of a three stage vehicle with a peak sensing device. Short betas were chosen for the 1st and 2nd stage and a short Mark Series for the 3rd stage. The peak sensor will be a photocell intended to detect the change from sky to ground and activate a parachute system. The 2nd and 3rd stage will be fired using inertia switches and a unique 3rd stage interlock system. A minor test will be of a passive sound emitter on the 2nd stage.

Also, (in this project) going to see if white, black or stainless is the best color to see (when spotting the rocket).

NOTE:
The report has sketches of the individual stages of the three-stage rocket and their interconnections.

first stage, shortened RRS standard beta, micrograin

2nd stage – shortened standard beta, micrograin rocket

3rd stage – Mark series rocket

556 timer chip, schematic

Sketch of the 3-stage rocket design

Second to third stage coupler design – sketch

Photo of the 3-stage rocket design

[more images and details to come, work in progress]

—- —-

For questions, contact the author, Frank Miuccio.
vicepresident@rrs.org

or the RRS secretary
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!