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Scalded Cat Steam Rocket Project Report

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by William J. Inman, Reaction Research Society

Editor’s Note: This article was originally published in the March 2001 issue of RRS News, an RRS print magazine. It is reprinted here on June 20, 2020, for the RRS.ORG website with permission from the author and from the RRS. Copyright belongs to the author and the RRS.

Some of the products mentioned in the article are still available and links to the company website are provided solely for the reader’s convenience but does not constitute an endorsement of any product by the RRS.

William J. Inman’s Scalded Cat Steam Rocket Project

STEAM ROCKET THEORY

Water has the ability to hold and store a tremendous amount of energy in the form of heat. Unlike more conventional propellants that store their energy chemically, the steam rocket, or hot water rocket as it’s known, relies on the amount of heat stored in the water. Two other properties of water that make the steam rocket work so well are the vapor pressure developed as the water is heated beyond it’s “normal” boiling point and that when released it will expand to 1700 times the volume it occupied in the liquid state. It can be heated to 700 degrees Fahrenheit (at 3200 psi) before it reaches it’s critical point. Power increases with heat, but so does pressure, so the farther up the scale it goes the stronger the tank needs to be to withstand the pressure. Optimum performance is a balancing act between power of higher pressure and the weight of a stronger tank. Obviously, the tank should be made of the strongest, lightest weight, heat resistant material available… Titanium would undoubtedly be the ultimate if cost were no object.

Vapor pressure of water at increasing temperatures up to critical point of 705 F.

In the nozzle, the water starts flowing as it enters the convergent section. The venturi principle causes the local pressure to drop as velocity increases through the nozzle, and as pressure drops, the water starts flashing to steam. This steam, as it expands, continues to accelerate in the divergent section. The percentage of water that actually becomes steam depends on the amount of stored heat in the water. The temperature will drop all the way to the ambient boiling point at the nozzle exit, being converted to kinetic energy in the form of jet velocity. This velocity can exceed Mach 2 in a well-designed nozzle. As the water level in the tank drops, it boils, keeping the volume above it filled with steam, maintaining the equilibrium. This also consumes some of the heat in the tank, so the tank pressure will drop about 25% during the course of the discharge.

THE ROCKET

The “Scalded Cat” Motor

At the time I started this project, I knew much less about steam rocket theory than I do now. The motor was based on a piece of surplus 4-inch diameter, type 316 stainless steel, schedule 10 pipe that I found. Wall thickness was 0.120 inches and the burst pressure as stated by the supplier was 4000 psi. I got a pair of stainless steel domed end caps and had them welded on, then a hole bored in the center of one and a 1-inch threaded stainless steel pipe fitting welded in for the nozzle attachment. Three steel fin-mounting tabs were welded to the nozzle end of the tank and a flange for mounting the payload section was welded to the other end. Compared to the 45 pound welding oxygen cylinder I used for most of my static testing, this was a lightweight tank, but at 24 pounds, it’s still pretty heavy for a flight tank. To take advantage of its strength and to partially offset its weight, I ran it at higher pressures than most previous steam rockets that I read about. The flight on December 2, 2000, was at 1500 psi tank pressure (610 degrees Fahrenheit). Theoretical specific impulse (Isp) at this heat is around 75 lb-sec / lb.

Welded-on steel fin mounts with nozzle screws into the bottom tank head.

The nozzle was machined aluminum with a 3/8-inch throat; a figure I arrived at because I wanted a throat area of 0.110 square inches. There was a curved convergent section who’s curve radius was 12 times the throat diameter, then the divergent section had a half-angle of 10 degrees (20 degrees between the walls) and an expansion ratio of 18.3 to 1. This made the exit diameter 1.600 inches. The throat was 1/2-inch long to give a pair of O-rings on the plug a place to seat.

Scalded Cat steam rocket nozzle design

The fins were 0.085-inch thick aluminum and were bolted to the steel fin tabs at the bottom of the tank by running machine screws through the fins and screwing them into the threaded holes in the tabs. The fins extended beyond the back of the tank and also bolted to tabs on the fiberglass boat-tail to help secure it. The boat-tail also had a ring at the back end that slipped over the nozzle to keep it straight.

Boat tail with aluminum fins bolted into the welded steel fin attach points. Nozzle retention points at the nozzle.

The payload section mounting flange was a piece of stainless pipe 1/4-inch smaller in diameter than the tank and 0.030-inch thinner. It was 3-inch long with three semi-circular notches cut in one end leaving three “pedestals” that were welded to the top of the tank. This reduced the steel to steel contact and hopefully the heat transfer rate from the tank to the flange. A total of six holes, three sets of two, were drilled and tapped in this flange for the mounting of the payload section adapter.

Vehicle Specifications

Length = 7.5 feet

Diameter = 4.5 inches

Weight (filled) = 53.2 lbs.

Water capacity = 8.5 liters / 2.25 gallons (80% full)

Operating temperature = 610 degrees Fahrenheit

Tank pressure = 1500 psi

Calculated tank yield point = 1800 psi

Estimated peak thrust = 297 lbs.

Thrust duration = 4.75 seconds

Estimated power = 5500 Newton-seconds, “M 1155”

Propellant mass fraction = 35%

Parachute (tank) = PML, 84-inches

Parachute (payload) = PML, 54-inches

Electronics = Adept ALTS2 and Blacksky AltAcc2

Deployment charges = 3 (redundant)

Charge igniters = 4 (redundant)

Bridle (shock cord) = Kevlar “muletape”

Fins = 3 (aluminum)

Nozzle throat area = 0.110 square inches

Nozzle expansion ratio = 18.3

Divergent cone taper = 20 degrees between walls

The Payload Section Adapter

This part was used to provide a slip-fit mount for the composite payload section while helping isolate it from the heat. It bolted to the mounting flange with six machine screws and extended 6.5 inches up beyond the end of the flange so the area in contact with the payload section would not be touching a hot steel surface on the other side. I needed something strong, heat resistant, a poor heat conductor, and made of a material I could work with. The only epoxy I could find that claimed to be good to 600 degrees Fahrenheit was J-B Weld, so it was thinned with lacquer thinner and used as the laminating resin for a Kevlar structure.

The top end of the tank and the mounting flange and eye-bolt. The payload section is in front of the motor. Notches in the Kevlar ring are to minimize contact with the payload tabs.
Looking down into the electronics bay. The plywood ring with ends of two “T-nuts” are visible with silicone “form-a-gasket” on the inner edge. AltAcc is mounted to the airframe (left) while a brass charge canister is inserted into the gas baffle for the backup charge (right). When the lid is installed, the altimeter and the other two canisters fit in between this other equipment (a close fit!).

J-B Weld – Adhesive Products

A J-B Weld and Kevlar ring was epoxied to the outside as a stop to keep the bottom edge of the payload section 1.85 inches above the upper edge of the steel flange. A Kevlar and J-B Weld “floor” or bulkhead was added to put another heat barrier between the tank and the payload section. Cellulose insulation was stuffed into the area between the tank and bulkhead.

The Payload Section

For this section, I used an 18-inch length of 4-inch phenolic tubing from LOC Precision with several layers of fiberglass wrapped around it.

LOC Precision – Rocket Kits and Accessories

I was concerned about the heat from the tank damaging it so I added 2-inch of Kevlar and J-B Weld composite to the bottom where it was closest to the metal flange. The bottom 11-inches of the payload section was open and housed the 84-inch PML parachute. The Kevlar “muletape” shock line was attached to a 3/8-inch eye-bolt in the top of the tank. Above this section was a 1/2-inch plywood bulkhead that housed a black powder charge and expansion chamber / stainless steel gas baffle section. There were two igniters in this charge, one connected to the Adept ALTS2 altimeter and the other to the Blacksky AltAcc2 accelerometer. These were to be triggered by the “main” event switches on the two electronic devices to blow the chute out if the 54-inch pilot chute hadn’t already deployed it. I did this for a backup system in case the payload section got soft and sticky from the heat and didn’t slide off easily as planned.

The whole steam rocket assembly with nosecone, payload and the metal propellant tank to hold the water propellant load.

There was a compartment above the bulkhead where the altimeter and accelerometer were housed. The three canisters for the powder charges were also in this compartment, blowing their gases through the bulkheads into the gas baffles. The canisters were 1/2-inch brass pipe nipples with 3/8-inch plugs inserted in one end with pipe threads, sealed with Teflon tape. The igniter wires were inserted through holes in these plugs and sealed with 6-minute epoxy. The AltAcc was attached to the inner wall of the airframe in the usual manner and the ALTS2 was attached to a piece of aluminum box tubing that was epoxied to the removable lid of this compartment.

The compartment lid was also 1/2-inch plywood with a 3/8-inch eye-bolt attached to it’s center and a gas baffle compartment on each side of the eye-bolt. The underside of this lid had a ring of Permatex “blue” silicone form-a-gasket where it sealed to the mounting ring. There were also two threaded holes, one at the base of each gas baffle, for the brass change canisters to screw into. Four stainless steel #6 machine screws held the lid to the mounting ring, which was made of 1-inch plywood epoxied to the inner wall of the airframe tube. “T”-nuts embedded in this built-up ring distributed the load from the screws. On the 3/8-inch eye-bolt was the Kevlar “muletape” shock line to the 54-inch PML pilot chute.

The Nosecone and Parachute Arrangement

The nosecone was a 4-inch LOC Precision unit with a wrap of 1.8 ounce Kevlar on the inside of the neck to help reinforce it after the bottom had been removed to gain access to the interior space. A 3-foot length of Kevlar “muletape” was attached to the inside of the tip of the nosecone by having a loop go around an aluminum cross-rod inserted through holes on each side of the nosecone tip. This whole assembly was then encased in a solid mass of epoxy, then the cross-rod cut off flush with the outside surface of the nosecone. On the other end of this line was a loop sewn in with Kevlar thread from Edmund Scientific. The 15-foot main shock line and parachute shroud lines were all attached at this point. The main shock line had accordion folds sewn into it with Kevlar thread. The stitches were not heavy duty so they would break when a load was applied. The first six folds had a single stitch holding them, the second set of six folds had a double stitch, the third set had a triple stitch and the fourth had a quadruple stitch. The idea was that the singles would break first, letting out 3 inches of line out at each break and adding tension. Then the doubles would start breaking, increasing tension and still letting out 3 inches per fold. By the time all the stitches were broken (which they were), hopefully things would be slowed down enough to keep the final shock from being too severe. (Kevlar does not stretch.) The 25-foot line from the tank to the 84-inch parachute was stitched up in this same manner.

Accordion folds were sewn into “muletape” Kevlar bridle line. Breaking the stitches allows the line to lengthen while adding increased tension and slowing the rate of separation, reducing shock when the line pulls tight.
The “recovery module” was built onto a 1/2-inch plywood disc that also served as the electronics compartment lid. The two gas baffles on the left of the disc with an eye-bolt between them are reinforced with Kevlar. The two brass change canisters (the far one is behind the altimeter) can be seen with the igniter wires in their end plugs. The Adept altimeter is bolted to a piece of aluminum box tubing.
The first flight of the Scalded Cat used the nose cone tot the left.

THE GROUND SUPPORT EQUIPMENT

The Launch Tower

Somehow I got the bright idea to build a tower with six longitudinal tubes of 1/2-inch electrical metal tubing (EMT). There would be one on each side of each of the three fins, just far enough apart to let the fin pass without binding. The reason was so I could pop rivet the three burner shrouds to these tubes, allowing each shroud to cover the entire tank surface between fins. “U” shaped strap steel brackets were welded to each set of tubes to hold them together and allow the fins to pass through. The three “U” brackets were held together by other pieces of steel strap welded to the outside corners, making a triangle shape at each of these brace points. The braces were spaced every 47-inches along the length of the 25-foot tower. For the real support, three lengths of 1-inch EMT were welded to the outside of the points of these “triangles”, also running the full length of the tower. In retrospect, diagonal cross braces should have been used and the second set of 1/2-inch tubes should have ended right above the tank where there was no longer any need for them. Anyway, it worked well enough. Three guy wires ran from the 12-foot point to anchors in the ground and another three ran from the 24-foot point to a second set of anchors 2 feet past the first set. Turnbuckles on all six ends made adjustment precise and easy.

The tower could be raised and lowered by pivoting on a stand which was a 3/4-inch galvanized pipe sitting in mounts on two 37-inch high welded steel “A-frames”. A flat attachment point was welded to two of the 1-inch EMT main supports and “U-bolts” went around the 3/4-inch pipe and through holes in the flats. To raise it, a couple of guys would get under the top end, raise it over their heads and start walking towards the base. After it was raised a certain amount, a third guy would start pulling a rope tied to the 12-foot point. A bolt on the bottom of the lower tower extension went through the base to hold it in position while the guy wires were being adjusted, and then help lock everything together.

The detached lower tower extension with the plug/release mechanism sitting in its notches. The release lever arm is sticking out in back. The fiberglass-covered styrofoam steam deflector is epoxied into the bottom. The hole in the flat bottom plate on the right is to bolt it to the plywood base.

The lower tower extension was a 17-inch piece of 7-inch diameter well casing with slots and access holes cut in it. A bottom plate was welded on for a place to bolt the plywood base, and three 3/8-inch headless bolts were welded to the upper end to bolt to the bottom of the tower. There was a fiberglass-covered styrofoam steam deflector in the bottom of this piece to direct the steam flow away from the electric actuators and the gas valve.

The Tower Base

This was what the tower sat on and what held all the peripheral ground support equipment. It was a 30-inch square piece of 3/4-inch thick plywood with two galvanized “Telespar” box sections bolted along the bottom of two opposite edges. These box sections were 36-inch long so they protruded 3-inches past each end of the plywood. Each of these four ends had a hole drilled in it to accept a 5/8-inch steel hold-down stake. The two welded “A-frame” tower supports bolted to the edges of the plywood base and had cross-bracing on the back side. A pipe coupler was welded to the top of each of these “A-frames” so the 3/4-inch tower support pipe could slide through.

A bracket to hold the release actuator was attached to one side of the tower and a bracket to hold the gas valve actuator was attached near the back of the lower tower extension. Then there was a third bracket to hold the clamp that secured the gas manifold near the back edge of the base. The plywood was thoroughly primed and painted to ward off the effects of the elements and the steam blast.

The Nozzle Plug / Release

Based loosely on the release mechanism designed by Bob Truax for his steam rockets in the 1950’s and 1960’s, this multi-talented device serves several purposes. First, it plugs the nozzle throat so no water or steam will escape before it’s released. Second, it provides a connection to the pressure gauge so it can be monitored during heating. Third, it has the integral clamping system that holds the rocket on the plug until released, and (provide) the means of releasing it.

The central plug is machined out of steel and has a long narrow taper to the 3/8-inch tip that goes into the nozzle throat. This tip is 0.60 inches long and has two O-ring grooves to accept Parker fluorocarbon or “Viton” O-rings to make the seal. The part below the taper is threaded with 7/8-inch bolt threads. A hole is drilled through the center to provide access to the tank pressure.

The plug/release mechanism locked onto the nozzle (boat-tail removed). The brass fitting connects to a steel brake line to the pressure gauge. Rotating the release cam (holding the red bars out) allows the bars to pivot off the nozzle.

The bottom end of the plug is drilled and threaded to accept a 1/8-inch brass pipe fitting. This fitting is an adapter that allows a 5/16-inch automotive steel brake line to be used to connect the pressure gauge, which sits on the tower’s 3/4-inch support pipe on the end facing the blockhouse.

A support structure with three “spokes” is built around a 7/8-inch nut that screws onto the plug. The “spokes” are steel box tubing long enough to reach past the wall of the lower tower extension and sit in the bottom of three dedicated notches in the extension. Each of the spokes has a rectangular hole cut in it’s top and bottom to allow a smaller piece of square steel bar to pass through. This bar is pinned to the spoke by a 1/4-inch bolt running through it crossways, allowing it to pivot. When the three bars are brought together at the top, they contact the tapered outer walls of the nozzle like fingers.

Below the structure with the spokes and bars is a cam plate made from a round piece of 1/8″ steel sheet welded to a bored-out 7/8-inch nut that slips onto the plug. Three equally-spaced half-round notches are cut into the edge of this plate. The spacing between the plate or cam and the “spokes” structure is adjusted with washers between the two. When adjusted correctly, the “cam” edges of the plate will hold the bottom edges of the three bars out at a distance that positions the other end of the bars so they hold the nozzle firmly onto the plug, with the O-rings seated in the throat by “gripping” the tapered outer walls like fingers holding a knob. Rotating this cam by pulling on an attached lever arm with a 12-volt DC electric linear actuator allows the bottoms of the three bars, or fingers, to fall into the three notches, pivoting around the 1/4-inch bolts and releasing the nozzle from it’s grip. A 7/8-inch “keeper nut” with a nylon insert is screwed onto the plug below the cam and give it something to ride on and keep the spacing so it turns freely but doesn’t have excess play.

The Burners and Gas Delivery System

At the bottom of the tower are three sheet metal burner shrouds that are as long as the tank (48 inches). In the bottom of each of these shrouds is a 30,000 BTU propane gas log lighter for a fireplace attached by two “U-bolts”. There are adapters for flexible appliance gas lines on each burner to attach to the manifold. The manifold is a 1/2-inch pipe nipple and “L’s” on each side, creating three points to attach the flex-lines. A clamp with three notches fits over these three lines at the manifold, holding it to the plywood base. On the other end of the feed nipple is a brass ball valve with a union on the other end. The rubber hose from the propane bottle is connected to the manifold at this union.

Launch tower erected with the power cables running back to the blockhouse, propane bottle to the right feeding the burners

Attached to the ball valve is an aluminum extension that is painted bright red so the valve position can be determined visually from the blockhouse. Also attached to the valve handle is the end of a 24-volt DC electric linear actuator attached to the control panel in the blockhouse. This actuator is used to open and close the gas supply to the main burners.

Electric linear actuators used in the launch process.
4.5-inch pressure gauge with a red plate behind it for easier visibility.
Sheet metail placed around the three burner shrouds for better heat retention. Propane torch igniters seen at the bottom. Steam pressure gauge is reading tank pressure.

Three small handheld propane torches are positioned around the base of the tower pointed up into the shroud burner areas. These act as pilot lights for the main burners should they need to be turned off and then back on again. They also add additional BTU’s to the heating effort but don’t put out enough to maintain heat (and pressure) by themselves.

The Control Devices and Panel

Pressure is monitored visually by watching a 4.50-inch diameter pressure gauge with binoculars from the blockhouse. Heating is controlled by a gas valve in the line to the main burners. A 24-volt DC linear actuator is attached to the handle of the gas valve and opens and closes it by pushing and pulling. It is wired to a double pole-double throw (DPDT) toggle switch on the control panel so that pushing it one direction opens the valve and pushing it the other direction closes it. It is a three-position momentary switch so releasing it allows it to spring back to the center “off” position. The power comes from two 12-volt batteries wired in series in the box. The control panel is actually the lid of the battery box.

The directional control switch and “launch button” are located under the safety flap on the control panel. Both the 24-volt system cord to the gas valve actuator and the 12-volt system cord to the launch actuator extending from the right side of the box.

Launch is initiated with another electric actuator, this one a 12-volt DC unit, also wired through a DPDT toggle switch in the battery box. Three 12-volt batteries wired in parallel power this actuator. One lead goes through a momentary red pushbutton switch wired in series with the DPDT switch. The DPDT is a two position, one for extend, the other for retract. This allows the cam to be rotated back to the “reset” position easily, which is good because we had to move it back and forth once to release the rocket for it’s maiden flight. The red “launch” pushbutton and the DPDT toggle switch controlling the direction of the release actuator are both under a spring-loaded safety flap made from an outside electrical box outlet cover.

Another view of the control panel with cable feed-through glands. Use of 12-gauge extension cords works well.

To connect the control box to the actuators at the pad, color-coded 12-gauge extension cord is used. Two 25-foot cords were bought, one yellow, the other blue with an orange stripe. Yellow is for the 24-volt gas valve actuator while blue-and-orange is for the 12-volt release actuator. These 25-foot cords were cut a few feet from the “female” end and attached to their respective switches in the box with the ends dangling outside a foot or so. The other long piece was wired to the actuators with the “male” end like a regular power cord on any appliance or power tool. Two 100-foot cords with the same color coding bridged the distance from the blockhouse to the pad.

THE MAIDEN FLIGHT

Setup and Preparation

The tower base already leveled and staked down on launch day and the tower was waiting nearby. The guy wire anchors were driven in at the pre-determined and marked spots and the peripherals were all attached to the base and tower. The igniters and deployment charges were already set up earlier in the motel room so once it was time to start the heating, the altimeter and AltAcc were turned on. After the tower was raised vertical and secured, the burners were lit and the AltAcc armed. We did not time the heating, but it went fairly quickly once a piece of sheet metal was wrapped around the tower at the position of the heaters. It was carefully bent so the fins would pass inside it during launch. When the pressure reached 1400 psi and then launch hopefully at a point where it had dropped to 1350 psi, the target pressure. Instead, the pressure continued to climb to 1500 psi, where it stayed until launch.

Bill Inman makes a minor adjustment to the fins of his steam rocket, the Scalded Cat
“Team Steam” shortly before the launch. From left to right: Jeanne Hoover, Bill Inman and Tim Clifford.

The Flight

When the release actuator was retracted, nothing happened. This had happened before, but when checked again during my last static test, it worked fine. Here we were sitting at 1500 psi with the release cam turned and the rocket just sitting there. So I had Tim Clifford, my partner and launch officer, switch the directional control to “reset”, work the actuator, then flip it back to “launch” and try it again. This time, after a couple seconds of hesitation, it took off on the most beautiful plume of steam I’ve ever seen. From the blockhouse it is not possible to visually follow a rocket very far into it’s flight through the small windows, so we just stood there listening to the roar as the sound came from farther and farther away. Finally, it stopped and for a brief moment there was no sound, until there was some cheering from the bunkers. The command was given over the P-A system to “quiet down”, and to “listen for an impact”. A few seconds later there was cheering again, and this time a more irritated repeat command was given only to be answered by shouts. “What was that?” … “A paraachute?” … “Two parachutes?” … “O.K. Keep an eye on it and stay under cover until the heavy piece is down.”

Launch of the Scalded Cat at approximately 2:30pm, December 2, 2000. Not the clearest view of the launch from behind the weathered blast windows of the blockhouse.
Another view of the steam rocket launch, photo courtesy of Richard Butterfield

Knowing it was under canopy was the best feeling of all. I have seen so many rockets crash because of recovery system failure that it makes that part especially critical. There was also the satisfaction of knowing that along with being the first successful steam rocket launch in the 57-year history of the RRS (at that time in the year 2000), it was also going to be one of the very few RRS flights to make a soft landing under parachute. I was able to squeeze out through the blockhouse door enough to actually see the parachutes coming down in the southwestern sky, the tank falling slightly faster than the payload section.

Parachute recovery was successful
Jeanne Hoover stands over the safely recovered motor.

Post-Recovery Examination

The only damage found was where the ring at the base of the boattail got broken in two spots from being driven into the ground from the weight of the tank. Otherwise, everything was all right and the altimeter was reporting 4,479 feet. That evening, Bill Seiders was kind enough to download the AltAcc on his computer. It showed a maximum acceleration of 128 feet per second (4 G’s) to a velocity of 506 feet per second (345 MPH), a coast time of 15 seconds, and a peak altitude of 4,400 feet.

Blast pattern after the steam rocket launch. Very little equipment damage after the launch.

Editor’s post-script: Bill Inman has decided to rejoin the RRS after being away for many years. We enjoyed talking with him at our virtual meeting on June 12, 2020. He spoke by teleconference as we are still unable to hold our meetings in person at the Ken Nakaoka Community Center in Gardena, California, due to the COVID-19 restrictions from the city of Los Angeles. Bill has decided to start a new steam rocket build based on the many lessons learned over the years and we hope he’ll teach some of us how to make this unique form of rocket fly.

December 2019 meeting

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Dave Nordling, Secretary, Reaction Research Society

The Reaction Research Society (RRS) met for our last monthly meeting of the year on December 13, 2019, at the Ken Nakaoka Community Center in Gardena, California. We had a full house with three different universities represented and a few returning members who came out to see how this year was ending for the society. The Compton College STEM club came out and some of them joined the RRS that night. Compton College is working on their own liquid rocket build which may next year see some important testing conducted.

Compton College STEM club at the December 2019 meeting of the RRS. From left to right, Katherine Perez, Desiree Medina, Erik Aparicio, Jamie Alvarez

Frank Chandler who is the director of Cal Poly Pomona’s (CPP) liquid rocket group and an RRS member was also at the meeting to discuss a March test date at the RRS MTA. He mentioned that Cal Poly Pomona recently had a tour of the AstroPak company in Downey, California. AstroPak has been in the business of cleaning mechanical parts for oxygen service for many years. The CPP students got to see each step of the process and learned the importance of maintaining this cleanliness throughout operations. Nearly all liquid rocket projects have decided to use liquid oxygen which has it’s own challenges to meet. Studying and keeping good cleanliness practices is paramount to avoiding catastrophe.

Chris Lujan and Frank Miuccio establish the link to bring in Richard Garcia, our director of research into the meeting.

We also were happy to have our director of research, Richard Garcia, calling into the meeting. Frank Miuccio and Chris Lujan have been very helpful in establishing a call-in number for some of our former and current members to call in when they are away from the city. We hope to have more of our membership calling in so that they may remain informed and active with their membership in the society. As per our tradition, we always value those making the trip to visit us in person.

After calling the meeting to order, and the reading of the treasury report, we covered our agenda items. We covered nearly all of our agenda and had time for special presentation from two members of Long Beach Rocketry at California State University Long Beach (CSULB). The purpose of their visit was to introduce themselves to the RRS.

CSU Long Beach presenters with their latest prototype on display at the December 2019 meeting of the RRS.
Frank Chandler sits at the table next to the Long Beach Rocketry team’s next assembly on display at the December meeting of the RRS.

Corey Fraga and Dan Dao gave us a short presentation of their team and some of their recent accomplishments. Their solid motor rocket project started in 2015 and has done well in recent competitions including the NASA University Student Launch Initiative (USLI) taking fifth place among a long list of worthy competitors. They also brought their most recent prototype vehicle which has a quadricopter drone built into the cargo bay. After the rocket completes its flight and gently touches down from its parachute recovery system, the cargo bay opens from an electric motor driven mechanism which allows the drone to take off and survey the landing site. The idea is to create a system that could be useful in planetary exploration or even in remote or dangerous areas here on Earth.

CSU Long Beach (Corey Fraga, Dan Dao) makes their presentation on their latest competition at Huntsville, AL.

The Long Beach Rocketry group offered to give the RRS a tour of their lab facilities on campus. The RRS graciously accepted their invitation. We should hopefully announce a date soon for this event.

Corey Fraga and Dan Dao finish their presentation at the December meeting of the RRS.

[1] Results from the last MTA launch

The launch report from the December 7, 2019, event has already been posted. We had a successful event despite an earlier concern for bad weather. Thankfully, the rain fell early and had cleared by Saturday morning. We were able to get our equipment set up for the event, but the society needs to invest in a simple sumping pump in case we need to remove any standing water from our bunkers or other enclosed spaces that have failed to drain from a recent rain or flooding. We are thankful to our neighbors at the Friends of Amateur Rocketry (FAR) for letting us borrow their sump pump.

Two students of 99th Street Elementary wait for the next launch in the RRS MTA observation bunker. Many of our observers could use something to stand a little higher to see better.

I also noticed that we could use a few more cinder blocks in the blockhouse. Many of our students are too short to see over the wall and the few blocks we already have are not enough. The RRS should buy a few more cinder blocks and possibly make some standing benches to help our students see their hard work better from the safety of the observation bunker.

An RRS standard alpha takes off into the moist air of December at the MTA.

Another observation made was the students from the neighboring Friends of Amateur Rocketry (FAR) site were often seen walking around too close to the RRS launching site as we were conducting road and air checks for our alpha rocket launches. It appeared that they were searching to recover their rocket from their prior flight, but we aborted three different countdowns due to car movements seen, or people crossing by on the north road adjacent to our property, and even one oblivious individual who was walking downrange of our own RRS MTA launch site as we were in the count!. The RRS and FAR must better coordinate our launch and recovery protocols respecting each others’ boundaries if only for the safety of all people concerned.

FAR and the RRS often conduct events on the same day and since our societies are sharing the launch areas and have many common interests, the RRS will work with FAR to find the best approach to assure safety and smooth operations for all.

[2] Next events at the MTA

Frank Miuccio is already working on the next event with LAPD CSP. The program will likely have its first class possibly on the Friday after the Martin Luther King holiday. Five to six weeks later means that the launch event could take place in late February or early March 2020.

I’ve been planning a launch event at the RRS Mojave Test Area (MTA) much sooner than that. For too many years, the RRS MTA sits empty in January and February for no good reason. I sought to undo this trend by holding an event just with our membership the way that our society used to operate.

At first, I was able to confirm Wolfram Blume who wants to fly his booster and ramjet upper stage system, if only for a system test of his booster, staging mechanism and recovery system. The ramjet upper stage will not be fired and will be loaded with an equivalent weight of water in its gasoline fuel tank to get the correct balance of the final vehicle. It’s a bit of risk to fly the actual ramjet prototype but there is no better way to get the right aerodynamics. It should be a good test and with luck his systems all pass the first flight test at the RRS MTA.

Larry and I have been talking about integrating a commercial hybrid motor into his 38mm fiberglass rocket. If I can acquire the motor parts, Larry will help me get the recovery system and the rest of the motor mounting complete. This will be the first hybrid motor launch from the RRS MTA in a very long time.

Also, John Krell voiced his interest in re-flying his improved avionics payload in an RRS standard alpha. This one will have an expanded accelerometer range to catch the ultra-fast burn of the alpha. He’s working on improving the data rate as recent open-source software changes have downgrading the sampling by half for some inexplicable reason.

CSULB’s Long Beach Rocketry team, (left to right) Corey Fraga and Dan Dao, Frank Chandler (CPP) and John Krell at the December meeting of the RRS

Brian Johnson and Bill Behenna each have avionics packages in development. The RRS has plenty of alpha boosters ready if members can get their payloads integrated into a suitable payload tube in time. We hope to confirm the launch manifest by New Year’s Day so I am hopeful we will have a fun launch day on January 18, 2020. We have also spread the word to our university project teams that the RRS MTA will be open for testing or flights if they can be ready on this date early in the year. The RRS encourages all teams to plan ahead and test early and often to assure their later success.

[3] Progress on the 2020 RRS symposium

Frank Miuccio, our vice president and symposium coordinator, has had some difficulties in confirming the symposium date, but we are hopeful that the April 18, 2020 will be the symposium date. We also may have the option for April 25, 2020. The Ken Nakaoka Community Center of Gardena will hopefully confirm the date for our symposium Monday.

The Long Beach Rocketry group and the Compton College STEM club have both indicated their interest in presenting or exhibiting at the 2020 RRS symposium. In many cases, it can be first come, first serve. This will be the fourth symposium in a row for us and we hope to continue the momentum we’ve built. I have a few government and private companies in mind to give us a great slate of speakers. We just need to confirm the symposium date.

[4] Treasurer’s report on the membership roster, dues payment policy change

Chris Lujan has been surveying the sign-up sheets from past months over recent years to help establish who has been attending meetings and how often. Active membership requires participation in the society as it does with any group. Attending monthly meetings is not the only means of staying active as attending launch events or participating in outside events also qualifies. The RRS is working on building a firm definition to make clear when a member is or is not active. This is important as our Constitution requires both an administrative membership class AND active membership to retain voting rights. Each year, we try to reach our past and present members but without effort on the member’s part to keep their information current, our elections and voting on important measures must go on without them. Contacting any member of the RRS executive council is the best way to keep the society updated on your whereabouts and contact information.. The membership roster is managed by the RRS treasurer.

treasurer@rrs.org

Chris is also working up some percentages for how many of our active membership are current with their dues payment. Initial estimates are encouraging, but since we have many new members who paid upon their induction, these high percentages make sense. It is our longer term members who are often neglecting their duty to keep their dues paid each year. Dues payment is also an essential element of membership.

The executive council has voted a policy change to when dues are to be paid. Effective immediately, all dues payments must be made by January 1st of each calendar year. I was glad that the society has supported this firm fixed date which makes accounting for dues much easier on our treasurer. The membership roster will also track dues payment and active membership status. For the several lifetime members in the society, this past membership class will remain and dues payment is not required for these persons, however, remaining active with the society is still a requirement to keep voting rights.

[5] 2020 Constitutional Committee report

Frank Miuccio was able to report that the 2020 Constitutional Committee has met a couple of times in the last two months and is reviewing the last page of the new draft. The committee will present its draft to the executive council at year’s end. The executive council will review the draft before presenting it to our administrative membership for consideration and a subsequent two-thirds ratification vote.

[6] Social media updates

Our social media coordinators were both not in attendance in December. The RRS continues to be active on Instagram. Our Facebook page needs some management. The RRS is also looking at trying to build a calendar feature on the RRS.ORG website to better announce events.

secretary@rrs.org

The RRS continues to use WordPress for its ease of use and simplicity, but the society has been considering reformatting and restyling our page or at least re-organizing the menu options to make finding common things easier. This will be a task for the new RRS secretary.

[7] CSFM committee on amateur rocketry

The California State Fire Marshal’s (CSFM) office has been holding hearings with the broader pyrotechnic operator’s community throughout the state this year. Most of the community is made up of the fireworks and special effects community. Amateur rocketry is a smaller and separate group which has our own interests we operate very differently from the other larger groups.

The RRS (Larry Hoffing), ROC (Chris Kobel) and FAR (Mark Holthaus) discuss a collective list of proposed changes to CSFM definitions governing amateur rocketry on 12/04/2019.

Mark Holthaus of FAR has been reviewing the definitions pages of the California laws relevant to amateur rocketry. The RRS and FAR have met on three different occasions in the last two months. The RRS has found FAR’s proposed changes to be very reasonable and accurately reflect how we can continue to operate safely. We have also included feedback from members of the Rocketry Organization of California (ROC) at the last two meetings. David Reese of ROC has been particularly helpful in improving and clarifying the language which governs our hobby and we are also grateful for his assistance.

Mark has made arrangements to discuss our proposed changes with the CSFM office on Monday, December 16th. We hope this informal meeting goes well and that all of our recommendations can be implemented which will assure both safety and legal operations for our groups. Some of the amateur rocketry groups are not national organizations and would be harmed by excessive regulation from the state. The CSFM office has been very welcoming and open to ideas thus far. CSFM has not often held these kinds of reviews and the RRS recognizes the great opportunity we’ve had to help shape policy for everyone in rocketry in California.

[8] RRS executive council election results for 2020

Larry Hoffing, our appointed election chairman for this annual election cycle, certified his results to the membership at our December 2019 meeting as required per our Constitution. Each officer was elected by unanimous vote. Our new executive council officers starting in January 1, 2020 are as follows:

Osvaldo Tarditti, president@rrs.org

Frank Miuccio, vicepresident@rrs.org

Drew Cortopassi, secretary@rrs.org

Chris Lujan, treasurer@rrs.org

The RRS is grateful to our election chairman, Larry Hoffing, for fulfilling his duties to the society. The council will appoint a new chairman next November when we hold nominations for the next election cycle. The society is thankful to our new and returning officers who have stepped up to serve the society for this next exciting year, 2020.

[9] Proposed RRS MTA standard fee schedule

The RRS has become increasingly active with more and more requests to use our Mojave Test Area (MTA). This is a very good thing, but often scheduling of hot-fire events has become excessively chaotic. The RRS understands that sometimes things happen that can force cancellation of a planned event with little or no notice. Weather is often the main culprit of such things. However, as one who has participated in coordinating launch events at the MTA this year in conjunction with our RRS president, I have seen many occasions when poor planning is the only reason for a last minute cancellation. Worst yet, the society has also received far too many last minute requests for use of our site. The RRS is in the process of drafting a standard fee schedule which will explain the requirements for outside users of the MTA. The exact details of this forthcoming policy are still under discussion, but the following is some of the ideas that were discussed.

The RRS is happy to help as many organizations as we can, but our customers must understand that:

(1) We are a volunteer society. Few, if any, of us are paid for the substantial time and resources spent to make these events possible. While we often generously donate our time to support and promote these events, the society needs money to operate and improve our site and this must come from charging fees to pay for repairs improvement projects. A standard fee schedule will be drafted, reviewed and approved by the society before the end of the year.

(2) We operate the RRS MTA by APPOINTMENT ONLY! There is no sign-up calendar like what is used by other amateur rocketry organizations such as FAR. We operate in this fashion because we stress the importance of advanced planning. Last minute requests for using the MTA site will very likely be rejected. Rocketry is a dangerous hobby and the importance of careful preparation is reflected in the desire of the RRS to accept only advance notification for all proposed projects. This not only makes planning events easier for all parties, but it makes them safer. Contact the RRS president for all requests to use the RRS MTA.

(3) Our indemnification forms are required to be signed and submitted by ALL PERSONS well in advance of attending the event. This includes spectators, spouses, significant others, and children. This has been standing policy at the RRS MTA and will remain so. Just showing up at our MTA site on the day of the event is NOT acceptable and people will be turned away if our policies are not respected.

(4) We expect several weeks advance notice to conduct a thorough review of each new project. This means that all groups must have their operating procedures, checklists, drawings, schematics already prepared for the pyro-op’s review when the request is submitted.well in advance of the requested event date. Expecting the pyro-op to examine your intended test article and procedures for the project only on the day of the event upon their arrival is NOT REASONABLE.

Events at the MTA will be conducted with a pyro-op appointed by the RRS. Our pyro-op should have had the opportunity to see everything well planned and well in advance. Attending RRS monthly meetings is an excellent way for potential users to familiarize themselves with the society and our expectations. Submitting your project description on an RRS standard record form a month in advance and was formerly policy at the RRS. Everyone must understand that the pyro-op in charge can refuse any test at any time for any reason making your journey out to the MTA all for naught.

Based on an accumulation of both good and bad experiences, I will undertake a project to draft an official RRS policy on testing at the MTA for our outside customers that will take affect on January 1, 2020. I was glad to get a lot of feedback from potential customers and other members at the December meeting. To our society members, please send me your feedback soon as I will be working this policy out in the next two weeks before the executive council approves it.

The RRS will begin charging standard daily fees for use of the MTA site and charging a separate daily fee for the pyrotechnic operator in charge at this event. Pricing may vary with private companies and universities, but in all cases, fees are expected to be paid before approval of the event is given by the RRS. Cancellations within two weeks of the event will result in forfeiture of all of those fees for that event date and new fees must be paid again for a new test date. When customers stand to lose their fees if they fail to deliver on their commitments to the RRS, they will better understand the importance of managing their projects better as they must now avoid the cost of cancellations. Other groups, both amateur and professional organizations, operate successfully with these kinds of policies and the RRS will be enforcing their own policies soon.

[10] Review of the Gas Guzzler ramjet project

Wolfram Blume and his wife were kind enough to stop by the December RRS meeting bringing his booster rocket for one more inspection. I will be the pyro-op in charge of his first test flight on 1/18/2020 and I wanted a closer look at how secure and stiff his fins were. Based on my inspection, his booster looks ready for rail launch. With luck, his staging and recovery systems will function without issue. Wolfram has borrowed from prior successful designs flown at ROC events in Lucerne Valley. The RRS is glad to assist him with this ambitious project.

Wolfram Blume stands with his booster used on the Gas Guzzler project.

[11] Solid propellant making classes

The RRS was approached about restarting our composite grain propellant making classes at the RRS MTA. After some careful assessment of our equipment, resources and available personnel, the RRS is not yet ready to offer these classes again. Twenty years ago, the society held a few of these solid motor building classes which became very popular. The RRS is building back our capabilities and this will take some time.

The Friends of Amateur Rocketry (FAR) has offered similar classes at their site and for the time being, the RRS must refer interested parties to them.

[12] SuperDosa project update

The SuperDosa project was established two years ago with the intent of the RRS restarting our large solid motor building skills to progressively build larger vehicles able to not only breach the von Karman line (100 km ASL), but surpass the current amateur rocketry altitude record holder. Despite our increasing membership, we have not had much progress to date. Given my commitments to several liquid rocket projects, I am handing over my leadership duties to Drew Sherman. Drew is a founder of Leo Aerospace and also an active RRS member. His interests very much align with this project and with the combined resources of others in the society building high powered motors, we hope that Drew can continue this project to its lofty goal of bringing the title back to the Reaction Research Society.

[13] RRS MTA facility improvements

Osvaldo Tarditti, our society president, continues to lead our MTA facility improvement projects, chief among those is improving our bathroom facilities at the site. Osvaldo has drafted plans for an improved bathroom facility at our remote RRS MTA site. The RRS will be soliciting bids from local contractors soon and we hope to commence this important improvement at the MTA sometime this spring and complete by the summer. The society has nearly enough funds for this project, but we are hoping to receive a few more thousand dollars to initiate this project sooner than later.

Also on our list of improvements is a blockhouse replacement, horizontal mounting plate at our testing area to create a regular interface pattern for future users rather than continue the unregulated drilling of anchor bolts (and the hated “male” variety of these anchor bolts) into our concrete slab. RRS members, Dmitri Timohovich and Wilbur Owens have been supporting the society on this improvement as it will require heavy equipment to place and secure this trench plate at the RRS MTA.

Larry Hoffing has recognized that the society will soon need a second 40-foot container for storage. We will be acquiring some new solid propellant mixing equipment and we need to rearrange our inventory in a more organized and accessible fashion. Whether this comes in the form of a new container on our MTA site or possibly one given to us from our site tenant, Polaris Propulsion Inc., remains to be seen. The society will continue to monitor progress and set goals to complete these tasks.

IN CLOSING

This will be my last monthly report as I am stepping down as secretary of the RRS. I have enjoyed serving in this role for the last three years, but it is time for me to allow a new secretary to lend his voice to you, our readers. I will remain active with the society, but only as a member engaged in many projects around the society. The society grows as we bring new members in and the society gets new ideas. It is also important that we also get new leadership from time to time. I hope to see more of our new administrative membership step up for these executive council roles in the future. There is no better way to help the society than with service.

As my last parting comment, I would encourage ALL of our membership to write and submit articles. The RRS.ORG website is one of the best ways we educate and inform the public about the things that interest the society in rocketry. Even simple academic subjects are excellent ideas. Next year, you may see a couple articles from me, but I want to encourage all of our membership to do more than just mention ideas in conversations, but write them down, text them, email them, convey them to the RRS secretary. It is the job of the RRS secretary to be the chief editor and means of publication for our membership. Past articles are welcome as we have re-printed ones from our long past. We also heartily welcome new content. Any time is a good time to submit.

Our next meeting will be held January 10, 2020, at the Ken Nakaoka Community Center at 7:30PM. If there are questions or corrections, please notify the RRS secretary. After January 1, this will be Drew Cortopassi.

secretary@rrs.org

With gracious thanks to the society, I hope to see everyone in the new year.

Group photo taken at the end of the December 13, 2019 meeting of the RRS in Gardena.

MTA launch event, 2019-09-21

Posted on by

Larry Hoffing, Events Coordinator, RRS

Photo credits: Osvaldo Tarditti

The Reaction Research Society held another launch event with the LAPD CSP. This event was with the students of Boyle Heights. We had ten standard alphas launched into the blue Mojave sky that day including some model rockets made by Russell Hoffing and my grandson.

A lot of different groups came out for this launch event at the RRS MTA, 09-21-2019

We had students from the CSU Long Beach liquid rocket team come out to make some measurements for sub-system testing that they are planning at the RRS MTA this year.

CSU Long Beach inspects the vertical mounting structure at the RRS MTA
Model rockets in the George Dosa building undergoing preparation for launch
Students from Boyle Heights get their orientation instructions at the RRS MTA
RRS events coordinator, Larry Hoffing; RRS VP, Frank Miuccio and RRS president, Osvaldo Tarditi

Returning RRS member, John Krell, had worked up two prototype instrumentation packages for flights in the ninth and tenth RRS standard alphas on that day. Both rockets were recovered and the results were impressive.

John Krell arms his payload integrated into one of two RRS standard alphas, 09-21-2019
One of John’s prototypes survived the flight and is laid out on the table in the Dosa Bldg.
John Krell examines the recovered SD memory chips to determine the flight profile from the RRS alpha. Over 100 G’s of acceleration at take-off max’d out the sensor!

Materials have been acquired to repair the adjustable rail launcher that was damaged in early August this year. Osvaldo has been busy at work on the repairs. The RRS has several facility improvement projects in the works and we hope to bring this rail launcher back to service soon for larger rockets (4 to 6 inches).

John will hopefully have a full report and an overview of his design. Both Bill Behenna and Brian Johnson are also working on their own instrumentation designs for the RRS standard alpha. With this recent progress, this should help our others members take better data.

Still photo from RRS alpha #3 of 10 launched at the MTA on 09-21-2019.

We’ll discuss more of the results of this event in detail at the next RRS meeting on October 11, 2019. The RRS meets every 2nd Friday at the Ken Nakaoka Community Center in Gardena, California. Stop in and see how things went.