MTA Launch Event, 2021-12-17

by Dave Nordling, RRS.ORG


The Reaction Research Society held its last launch event of the year 2021 at the Mojave Test Area on Friday, December 17th. I was the pyrotechnic operator in charge. This was my first launch event as a Class 1 pyrotechnic operator although none of the activities this day involved a liquid rocket. We had four launches planned for that day. Two from Keith Yoerg, one from Wolfram Blume and one from Dimitri Timohovich. RRS members Wilbur Owens, Xavier Marshall and Bill Inman came to be spectators at this launch event.

Bill Inman at the RRS MTA on 12-17-2021

IMPROVEMENTS TO THE 1515 RAIL LAUNCHER

The first flight of the Hawk in late November revealed a concern about the stability of the 1515 rail launcher with heavier rockets. Although quite heavy in its steel rectangular tube construction, Dimitri and Keith used cinder blocks and sandbags to weigh down the legs of the base. This resulted in damage to several of the sandbags from the exhaust of the M-sized motor from the initial flight.

Flat steel plate with welded bolt
Flat steel plate added to the 1515 launch rail base for greater anchorage

A flat steel plate with a threaded rod welded to the center was connected to the bottom of the 1515 rail launcher to allow for more weight to the base and allow for more cinder blocks to be added for even more stability. New adjustable feet were added to the existing four threaded holes at the far points of the legs. Eyebolts were also bought to screw into the 3/4-10 holes in the pad to strap the base down if necessary.

The 1515 rail launcher with its new anchor plate held down by cinder blocks.

SECOND FLIGHT OF THE HAWK

The December 17th launch event was primarily for the second flight of Keith Yoerg’s massive 14-foot long, 8-inch diameter Jumbo Dark Star rocket made by Wildman Rocketry with a 98mm Cesaroni N2600 Skidmark motor. The launch was held on Friday to coincide with the anniversary of the Wright Brothers first flight..

The payload tube of the Hawk being prepared for launch on 12/17/2021.

The payload was something very special to the Yoerg family and to American aviation history. The payload was a few squares of cotton fabric from the right wing of the original Wright Flyer aircraft that made aviation history. This cloth was the actual material that flew in 1903.

An authenticated piece of American aviation history flies on the Hawk from the RRS MTA.

A similar piece of the cotton fabric used in the Wright Flyer was sent with the Mars Ingenuity helicopter aboard the Mars 2020 mission being part of the first aircraft flown on a foreign world.

Mars Ingenuity helicopter at Jezero Crater on the surface of the Red Planet in April 2021

It was amazing to fly a similar piece of history at our humble launch site for our members to enjoy on the anniversary of manned flight.

After securing the payload and verifying the recovery systems were in proper working order, the Hawk was taken to the launch pad and erected for flight.

The Hawk slid into the 1515 extrusion rail by its rail buttons.
Manually erecting the Hawk took several people to carefully raise and push the stopping pin once the rail was near vertical.
Keith checking out the wireless data system.
Dimitri connects the igniter circuit into the society’s new Cobra wireless firing system
Keith Yoerg and Xavier Marshall of the RRS pose with the Hawk before its second flight on the Wright Brothers anniversary.

Before the countdown, Keith gave a very moving speech with his mother, Janette Davis, present in the observation bunker.

118 years ago today, on the sandy windswept dunes of Kitty Hawk, North Carolina, my Great-Great Granduncles Orville and Wilbur Wright achieved the first powered, heavier-than-air flight of a manned aircraft. A few small pieces of fabric from that historic airplane are ready to take flight again today, from the sands of the Mojave Desert, aboard ”The Hawk” an 8-inch diameter 14-foot fall rocket Honoring Aviation, the Wrights, and Kinetics. In 1903, this fabric reached a max altitude of 10 feet at a max speed of 10 feet per second. Today, that same fabric is expected to reach an altitude of over 7,000 feet with a max speed of 791 feet per second (or Mach 0.7).

We’re now ready to start the countdown. The sky is clear, the road is clear.

Flight 2 of “The Hawk” is launching in 5… 4… 3… 2… 1…

Rail-mounted camera caught a few frames before the N-motor destroyed the lens.

The second flight of the Hawk was close to predictions reaching over 7,800 feet in altitude and 742 feet per second. The Hawk with its drogue and main parachutes working properly was fully recovered. Keith got telemetry data and provided screenshots of the results below.

Telemetry data from the second flight of the Hawk on 12-17-2021

Beckie Timohovich was a big help in the recovery efforts and bringing back the hardware to the launch site. She also makes really good Alaskan caribou chili which we all got to enjoy at lunch in the Dosa Building.

The ratcheting extraction tool for removing alphas from the ground.
The Hawk returned safely to the ground with the historical payload intact. Wireless and onboard data was recorded and video footage from the ground and on the vehicle was recorded.

The 1515 rail launcher with its heavier base worked well and did not shift although the straps were singed by the hot exhaust and seemed to be superfluous. The parachute system on the Hawk deployed well and brought the vehicle down in tact. Most importantly, the family heirloom flown as a payload was returned to safekeeping.

The 1515 rail after launching the Hawk. Unfazed and ready for another pounding from Wolfram’s K-sized booster motor

Keith is considering his next flight of the Hawk. One idea is to fly an even larger motor if an O-sized motor will fit in the existing 98mm mount. The goal being to go faster and break the speed of sound and fly even higher. Keith was also pondering adding a second stage to the Hawk. We hope to learn his next plan in the new year as we hope to have another launch event in January 2022.

TWO MICROGRAIN ALPHA ROCKETS

We flew two alpha micrograin rockets. One by Keith Yoerg, one by Dimitri Timohovich. Each had a payload built by John Krell. These were the first zinc-sulfur rockets to be loaded and flown by Keith and Dimitri which although both them have been active members of the society for years, this experience served to initiate them into the RRS.

Dimitri was first to load his blue nose-to-red finned rocket and fire it while Wolfram Blume completed his assembly and preparations for the second flight of the Gas Guzzler two-stage rocket with a water ballasted ramjet upper stage. Keith Yoerg’s alpha with the bright pink nosecone and fins was the second of two alpha flights, Like with the Hawk before it, the RRS used our Cobra wireless firing system with the alpha rockets.

Dimitri Timohovich loads the powdered micrograin into the propellant tube using gentle vibration to release any air pockets.
Keith finished with the loading of powdered propellant, installs the nozzle into his alpha.

https://www.cobrafiringsystems.com

Keith edited the footage of both alpha flights into one compilation on YouTube. See link below:

John Krell’s Adalogger design custom built for the tight confines and high acceleration of Keith’s RRS standard alpha.
Keith prepares to load his alpha into the box rails.
Still capture of Keith’s alpha streaking nearly straight up in nearly calm winds that day.
Keith Yoerg’s first alpha rocket.

A few days after the MTA launch event, John reported a summary of the results from the two different instrumentation payloads. His emails are paraphrased below.


On 12/17/2021, two Alpha rockets were launched. Both were instrumented with high speed flight computers. Dmitri’s Alpha (blue nosecone) carried an original Alpha Datalogger on it’s third flight and Keith’s Alpha (pink nosecone) carried a newer Adalogger design on it’s second flight.

John Krell had two data logger designs. the original data logger design was flown on Dimitri’s alpha.

The bad news first. The Adalogger SD card socket broke during its first launch. I did not catch this issue prior to this launch. The SD card fell out of its socket during the initial acceleration and no flight data was recorded from Keith’s alpha, The next design update will include a nylon post to prevent SD card ejection. Keith’s Alpha also incorporated a semi-soft shock absorption mounting. It didn’t work as well as planned, but it does show potential with two modifications. Damage to the Adalogger system was minimal and repairable. 

9-volt battery mounted in the aluminum nosecone of Dimitri’s RRS alpha.

Dmitri’s Alpha produced significant new data during the burn for a micrograin rocket. The thrust was relatively smooth and constant compared to the previous three Alpha launches that carried flight computers and returned data. Absent were the large acceleration bursts during the burn. (See attached graph)

Acceleration plot of Dimitri’s alpha flight.

Also recorded was the impact. The impact duration was measured at 16 milliseconds. This is the shortest impact duration recorded for an Alpha. A prior impact duration of 18 milliseconds produced a deceleration of 716 G’s. This impact deceleration should exceed that value.

Further analysis of the data is required to determine a value. A picture of Dmitri’s rocket in the ground prior to extraction will be helpful.   (Photo was later provided.)    

Motor burn duration           0.408 seconds

Maximum Acceleration       103.95 G’s at 0.304 seconds

Maximum Velocity               676 ft/sec, Mach 0.6 based on integrated accelerometer readings  

Altitude at Burnout              ~138 ft    

Maximum Altitude                4,307 ft AGL by barometric readings

Terminal Velocity                  463 ft/sec, Mach 0.411  based on barometric readings

My video records of Keith’s Alpha show a shorter burn duration equating to a higher acceleration and velocity. The altitude should also be higher with the shorter down range distance. 

Dimitri’s alpha with its red paint at the aft body coming off from the intense heat of the micrograin burn. Dimitri’s rocket was found significantly further downrange than Keith’s but on the same heading

The still pictures at the end furnished the information necessary to estimate the deceleration at impact. Keith’s alpha’s penetration depth of approximately 3 feet 10 inches correlates to a deceleration rate of 680 to 720 G’s in a span of 18 to 20 milliseconds. Dimitri’s Alpha penetrated approximately 3 ft 8 inches into the ground in 16 milliseconds equating to ~900 G deceleration rate. Wow!!! 


The main objective was to give all of our active members experience with micrograin rocketry. Although rarely practiced outside of the society, it is considered to be something of a rite of passage and also serves as valid experience with the unlimited category of rocketry. This event gave Dimitri and Keith this experience which will help them as they advance as pyrotechnic operators.


SECOND FLIGHT OF THE GAS GUZZLER RAMJET

Wolfram Blume brought his second build of the Gas Guzzler rocket to the MTA for a December test flight. The same booster section with an Aerotech K-motor was flown. The ramjet was rebuilt and was flying a 3/4 load of water in the gasoline tank to have a representative payload weight including any possible sloshing that might occur.

Wilbur Owens discusses the ramjet operation with Wolfram Blume. This forward view is without the forward cowl. In the background is a graduated cylinder for precisely metering the fuel load into the ramjet.
The forward end of the ramjet with its annular cowl and forward spike as it nears final assembly.
The Gas Guzzler booster stage design remained the same for this second flight from the MTA.
Wolfram holds the lower half of his ramjet ready for final assembly and stacking of the two stages.
Wolfram carefully walked the ramjet upper stage to mate with the booster stage already on the launch rail.
Wolfram Blume and John Krell examine the Gas Guzzler on the 1515 launch rail before its second flight.
The Gas Guzzler sits side-saddled in the 1515 rail launcher to allow proper clearance of the fins.
The Gas Guzzler lept straight and clean from the 1515 rails in its booster flight.

From the ground, it was clear that the booster flew straight and stage separation had taken place. The booster parachute ripped loose. The ramjet came down only under its drogue chute and the hard landing damaged the upper stage enough to warrant a complete rebuild.

Clean stage separation was evident, but the booster parachute ripped loose.

Wolfram spent several days after the launch event looking at the remains of Gas Guzzler. A few things are known so far:

The addition of 1.14 kilograms of ballast water did not cause any problems. The two stages – both separately and together – were still stable in flight. Also the stage separation worked.

After separation, the booster came apart at apogee into two pieces. It is an easy fix as a bulkhead blew out and only needs to be better reinforced against the loads. A recent addition of a GPS tracker to the second flight of the booster worked.

The ramjet lost electrical power at apogee. The reason was found and will be repaired.  The power failure meant that the GPS tracking stopped at apogee which is a serious problem. Wolfram is considering adding a backup GPS tracker to the ramjet with a separate power supply.

Based on telemetry, the deceleration seen after stage separation gave the drag coefficient (Cd) on the ramjet at 0.25. The accuracy of this calculation is about 10% based on the acceleration readings which is fairly good all things considered.

drag force = Cd * velocity-squared * air-density

The thrust also scales with the square of velocity and that gives the minimum velocity when thrust minus drag exceeds weight to be about 656 feet per second (200 m/sec).  This is the minimum velocity which the booster must supply at burnout.

For this flight using the K-motor in the booster, with the water ballast, the maximum velocity was 574 feet per second (175 m/sec). The ramjet reached an apogee of 3,800 feet AGL (above ground level). The booster pushing the ramjet reached an apogee of 3,100 feet AGL. Maximum acceleration under boost phase was 6 G’s. The ramjet was flown without fuel, only an equivalent weight of water instead of gasoline.

The next build of the Gas Guzzler will have a larger booster which will hold an L-sized motor.

In the 12-17-2021 flight, the ramjet’s drogue parachute deployed correctly but the main chute did not. This seems to have been caused by the drogue chute being too small. Rockets with dual-deployment parachute recovery systems typically split the rocket in two places with the drogue ejecting forward and the main ejecting backwards. It is a good, reliable system but it cannot be used in the Gas Guzzler design because you cannot split the ramjet in the middle. Both of the parachutes must deploy from the front. The recovery system design requires the drogue to pull the main out of the ramjet at 1,000 feet.  Wolfram developed this system on prior rocket with launches at ROC in Lucerne Valley and it has worked the last three launches. Wolfram is confident that it will work in the next flight of the ramjet, too.

Damaged fragments of the ramjet recovered downrange after the second launch of the Gas Guzzler.

The air flow measured inside the ramjet during the second flight on 12-17-2021 was within the range of an air blower system at Wolfram’s workshop that had considered using to static fire the ramjet with an operational burner. However, he is not comfortable with trying the main burner at his workshop, but testing the flameholder and its igniter is OK. Thus, a static test of a fueled ramjet coupled with an air blower system is being considered.

Going forward, once the ramjet is rebuilt, Wolfram would like to verify the performance of the igniter and flameholder over the full range of the air blower’s speeds in a static fire setup at the MTA. In this testing, he also wants to work on how quickly the flameholder ignites to avoid losing a lot of forward speed after stage separation.

Wolfram will rebuild the ramjet as quickly as possible and could be ready for another launch in February 2022. He would like to do another booster-only flight from the MTA to verify the fixes on that stage. If successful, then the next launch will try a flight with a short ramjet burn using roughly 5 seconds of gasoline fuel.

The society will peer-review the work done so far and find the best way to proceed. Wolfram is still evaluating the data and may have an update to this firing report later.

TESTING OF A GERB AS A LIQUID ROCKET ENGINE IGNITER

Dimitri and I have overseen a few recent liquid rocket engine static fires at the RRS MTA. Although there have not been any ignition problems, we had discussed different approaches to getting a safe and reliable start.

Liquid rocket engines sometimes have problems with achieving reliable ignition. Failure to ignite the cold mixture of propellants due to lack of sufficient energy or outright failure to light can create a serious fire or explosion hazard. One of the simplest approaches is to use a sufficiently energetic pyrotechnic device mounted in the engine throat from the aft side. Visible indication of the igniter firing should be confirmed prior to opening the propellant valves and releasing the stored pressurant gas.

There are a few different pyrotechnic devices that are good for this task such as lances and gerbs. Both require a special license to get. Dimitri, who has such a license and happened to have a couple gerbs that we could try. Lances have been used in prior liquid rocket engine firings and vehicle launches with success.

https://en.wikipedia.org/wiki/Gerb_(pyrotechnic)

https://en.wikipedia.org/wiki/Pyrotechnics

At this event, we decided to test a gerb to see if it would be appropriate to try in lighting a liquid rocket engine. We secured one to the top of the alpha box rail and fired it to examine the plume,

A gerb is a pyrotechnic device used in firework displays.
Simple schematic of a liquid bipropellant rocket engine with an external igniter system
The gerb was fired to determine if it would make a suitable igniter for a liquid rocket engine.

Our impression of the gerb operation was favorable in terms of its 20-second firing duration, but it seemed that a smaller gerb size might be sufficient. Smaller gerb sizes are available. There is also the long-term consideration of having these available for liquid rocket testing which would require a storage magazine. Other less complicated means should be explored.

IN CLOSING

Several of the attendees stayed behind to clean up the MTA and relax in the Dosa Building. This was the last launch event for our outgoing president, Osvaldo Tarditti, who has faithfully served the society for many years with his time, skills and leadership. We enjoyed the sunset on a mild and nearly calm winded day. It was a fine end to a great day at the MTA and what was our last event of 2021.


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October 2021 Virtual Meeting

by Dave Nordling, RRS.ORG


The Reaction Research Society held it’s monthly meeting by teleconference on Friday, October 8, 2021. Some of our members were on travel, but the those in attendance were able to discuss several important issues.

The USC RPL static fire event on 9-26-2021 was safely conducted but ended in a explosion and fire which was ably contained. This was a good example of careful preparations and good management of the people present for the event. A firing report has been posted for this event. Osvaldo Tarditti was the pyrotechnic operator in charge that day.

UCLA had requested the use of the MTA on 10/16/2021 for their next liquid rocket engine test. The MTA was already reserved for Bill Claybaugh’s solid rocket flight that same day and in the days leading up to the event. Dave Nordling was the pyro-op in charge, A firing report for this event will be posted,

UCLA is planning to hold their conceptual design review (CoDR) on 10/22/21 for the next iteration of their liquid rocket. RRS members Dave Nordling and John Krell plan to attend.

Wolfram Blume was on the call and said he was eager to return to the MTA for a second flight attempt of the Gas Guzzler ramjet. With the summer heat gone, he hopes to return at our next launch event which is still being planned. It is hoped that the society can continue their streak of having at least one MTA event per month as we have done since the start of 2021.

The restroom container was purchased and brought to the Compton Airport for interior construction. This 20-foot high cube has a 9.5 foot ceiling and should be able to have two individual rooms with toilet and sink, one of these to have a shower stall. Osvaldo had drafted a floor plan and this was approved by the council. The society will be meeting at the Compton Airport on Saturday, October 23rd, for a late morning barbecue and an in-person discussion of the materials needed to get the restroom interior built. All members are welcome but please notify Keith, Wilbur, Xavier or Dave Nordling if you’re coming as they have access to the airport.

RRS containerized restroom awaits interior design and build

There was some discussion about the septic system and leach field. It is important to maintain an appropriate distance from any nearby water wells, one of which is on Polaris Propulsion property. Sufficient clearance exists based on measurements made and EPA guidelines. The leach field will be positioned to drain away to the north.

The society is considering buying a concrete septic tank but RRS member Wilbur Owens may have a plastic septic tank already available for the society. Some members feel a concrete septic tank will last longer and be less likely to leak. The council is still debating this feature and should render a decision soon.

The society also discussed the water supply to the restroom container and the supporting structure needed to hold a tank on top of the container. There are many important facets to this infrastructure addition which must be weighed carefully.

Nominations for RRS executive council offices will be held at next month’s meeting, November 12th, 2nd Friday of the month at 7:30pm. An election chairman will be selected beforehand and this person must be an active member not holding office nor running for office. A special email address will be set up for the election chairman to gather votes from our active administrative and lifetime members. Results to be announced at the December 10th meeting and new terms to start January 1, 2022.

For any questions, please contact the RRS secretary.

secretary@rrs.org


May 2021 Virtual Meeting

by Keith Yoerg (RRS Secretary)


The latest meeting of the Reaction Research Society took place this past Friday, May 14th and had 20 attendees – including a guest presenter and a project update from the Compton Comet team, which is composed of RRS members. We kicked off the meeting saying vitrual hello’s and catching up on personal updates.

Screenshot of discussion during the monthly meeting

UPCOMING EVENTS AT THE MTA

The group kicked off society business by planning for upcoming MTA events later this month. Wolfram Blume is continuing progress on the Gas Guzzler, but windy forecasts continue to limit his ability to do further launch testing. Osvaldo and Wolfram planned to visit the MTA on May 16th to do a practice setup for a future static firing and some housekeeping tasks at the property.

Osvaldo also informed the membership about an active day planned for Saturday, May 29th with groups from UCLA planning to do another static firing of their hybrid motor and a liquid rocket launch to 33,000 ft. and a team of students firing model rockets. Several additional RRS members expressed interest in attending this event.

GUEST PRESENTATION – COBRA FIRING SYSTEMS

Scott Smith, the founder of Cobra Firing Systems was our guest presenter for this month, continuing our recent discussions on wireless launch controllers. Scott has been in the pyrotechnics industry for 10 years, and developed Cobra into a 25-person company with roughly 14,000 customers around the word. They have worked with Mythbusters, Disney, and the US Military to name a few.

Scott describing the underlying technologies behind the Cobra Wireless Firing Systems

RRS member questions for Scott focused on safety, in particular the risk of misfires and adding a physical shunt to the system. The data is encrypted, includes checksums, and is built around a US-based company Synapse, which has allowed the company to avoid any reports of accidental misfiring due to stray wireless signals. Cobra firing boxes are modular in nature and allow for what the company calls a “slat” – which allows for a cap to be used as a physical, mechanical shunt on the system.

MEMBER PRESENTATION – COMPTON COMET

RRS student members Manuel Marques, Aarington Mitchell, and Tre Willingham presented on the status of their project the “Compton Comet” which is being built at the Compton Airport under the guidance of RRS members Waldo Stakes and Dave Nordling.

The Compton Comet team presenting to the membership

The rocket is a 75% ethanol & liquid oxygen bi-propellant rocket with a regeneratively-cooled engine. The engine is a surplus XLR-11 which should produce roughly 1,500-lbf of thrust, and was originally used in a group of 4 to power the Bell-X1 (the first aircraft to break the sound barrier). The rocket is estimated to reach an altitude of 20,000 km and will use a 2-parachute dual deployment recovery system.

THE FUTURE OF IN-PERSON RRS EVENTS

Members discussed the likelihood of in-person RRS events like the Symposium and meetings at the Gardena Community Center in 2021. It mentioned that the Symposium typically takes between 90 to 120 days to prepare, and it would be unlikely that the RRS would host one before spring 2022. There was a bit more of an optimistic outlook on the monthly meetings with a tentative goal set for a return to the Community Center in August (pending COVID restrictions).

MTA PERMANENT BATHROOM STATUS UPDATE

Designs and plans for the permanent bathroom structure at the MTA have been the main focus of the ongoing, twice-monthly meetings of the RRS Executive Council. Frank updated the membership on the current status of the project, which has gone through several iterations. Currently, RRS member Wilbur is working with professional drafters to get precise designs on paper – including model numbers for things like toilets and water heaters. A precise, written design will help the society get a final product that matches expectations.

The current plan is to build 2 or 3, 20-foot containers with 2 bathrooms each or 1 bathroom and 1 shower. These will be transported to the MTA and installed on concrete plinths which drain to a concrete septic tank and leach field. Water will be supplied by a well and stored in a tank installed on top of the bathroom or a nearby storage container. The bathroom facility is planned to be located southeast of the Dosa building, alongside the existing storage containers.

RRS BY LAWS

The RRS Executive Council has reviewed the recommended changes to the By Laws provided by the 2020 constitutional committee. Following are the By Laws as agreed to by the 2021 RRS Executive Council:

2021 RRS By Laws

LAUNCHING & STRUCTURES

Richard Dierking raised a question regarding the new structure being built on the Polaris land adjacent to the RRS site, and whether it must be considered an occupied structure during launch testing at the RRS site. This prompted a lively debate about the nuances of the regulatory framework around rocket activities in the Mojave desert, with several members voicing their opinions.

Safety of all personnel must be the #1 priority during activities at the MTA & communication between between the RRS, FAR, and Polaris is the best way to ensure that. Concurrent operations at adjacent properties are avoided when possible, and the RRS maintains relationships with our neighbors so that the Pyrotechnic Operator in charge is in contact with & can ensure the safety of personnel at adjacent property when operations overlap.

NEXT MONTHLY MEETING

The next RRS monthly meeting will be held virtually on Friday, June 11th at 7:30 pm pacific time. Current members will receive an invite via e-mail the week of the meeting. Non-members (or members who have not received recent invites) can request an invitation by sending an email to:

secretary@rrs.org