Steam-powered rockets?
 

Hello All,

Molniya's recent posting about launching his Vashon (or Estes) Valkyrie II Cold Propellant model rocket (see: http://www.oldrocketforum.com/showt...8973#post148973 ) got me thinking about a possible substitute model rocket technology that would function in substantially the same way.

In James Shortal's book "A New Dimension" (Bunny has my former copy :-) ), there is a short section (which includes a photograph) which describes an educational steam-powered rocket (about 2-1/2' to 3' long) intended for high school and college use that the late Admiral Robert C. Truax developed and tested at Wallops in the late 1950s. It included a launcher base that provided the boiling water for the rocket. It was a forerunner of the much larger steam rocket motor (not unlike a big Valkyrie motor) that powered Evel Knievel's Sky Cycle in which he attempted to jump the Snake River Canyon in 1974 (its parachute opened prematurely, but its steam rocket motor worked just fine). Now:

A steam-powered model rocket could be very similar to the Vashon/Estes Cold Propellant model rockets, even down to the timer/separator mechanism (although some material substitutions would be necessary because of the different propellant). Instead of being made of paper, the timing discs could be thin metal discs with fine, laser-punched perforations. Regarding the steam rocket motor itself:

The motor case could possibly be made of aluminum, as the Cold Propellant motors were, or thin stainless steel could be used. The nozzle extension could be made of a high-temperature plastic (possibly fiber-reinforced) or a suitable metal or alloy. A small spring-loaded, pressure-relief valve (calibrated to open when the steam pressure inside the motor was at flight pressure) could be installed near the rocket nozzle and be fitted with a "T-shaped" vent tube so that the escaping steam would not impart any spin to the rocket. The rocket motor could also have a replaceable blow-out safety valve like those found in pressure cookers. Also:

A launcher base with an integral water tank (*or* with fittings to hold a 2 liter soft drink bottle that could hold the water) would include a launch rod & jet deflector, a heating element (which could be energized by a 12 volt car battery, an R/C battery pack, or a 120 volt AC power supply (for situations in which AC power is available), a steam feed pipe that would fit into the rocket nozzle, and an electro-mechanical rocket release mechanism. In addition:

The remote launch controller (similar to existing ones) would have *two* controls (in addition to a safety key)--an ON/OFF switch for the heating element, and another to activate the rocket release mechanism when the model's pressure-relief valve began visibly venting white water vapor (thus indicating to the model rocketeer that its motor was at flight pressure). The release mechanism could be designed so that its activation would automatically shut off the heating element.

I'm pretty sure that Turd-Burd Evel Knievel 'rocket' that fool tried to jump the snake river canyon with was steam powered. Not sure you want to emulate anything about that fool...
I STILL say that jerk bailed and yanked the chute early NO MATTER what some others may THINK.

I saw a 1 foot diameter 4 foot long motor steam rocket fly at RRS. It's nozzle was about 1/4-1/2" and it was heated and when ready the plug was pulled.

Jerry

I think there was an article in Extreme Rocketry that was a "How To" make a steam powered rocket. That may have been the '05 to '06 time frame.

Greg

Rocket grade peroxide and a catalyst grid... there ya go...

If it was good enough for the turbopumps on the V-2, it's good enough for me! :chuckle:

Later! OL JR :)

The HTP monoprops I have tested have about 113 ISP. The steam rocket had an ISP of something around 20-40. On par with zinc-sulfur at 40. Estes BP has about 60-80.

Jerry

Shilling for Massachusetts now, are we????? ;)

Hello All,

I very much appreciate your replies, and I shall attend to all of them here:

I don't think you read my initial posting closely. If you had, you would have caught the part that mentioned equipping the steam rocket motor with *two* pressure-relief valves (a calibrated spring-loaded one to visually indicate flight pressure in the motor by venting steam, and a replaceable pressure cooker-type blow-out safety valve) to provide -two- redundant ways to prevent a steam explosion...but I do thank you for posting the link to the entertaining video nonetheless.Yes, it was steam-powered; Admiral Robert C. Truax (a bona fide rocket engineer) designed the Sky Cycle's rocket motor. While the vehicle's combination guidance system/"parachute ejection charge" (ol' Evel himself) may indeed have "malfunctioned" as you suggested, the Sky Cycle's steam rocket motor worked as it was supposed to. "Blame the man, not the motor." :-)Thank you for posting this link! Tim Pickens' big steam rocket is conceptually similar to what I have in mind. Speaking of the "dirt" (asphalt fuel) rockoon that you described in the above-linked posting, a solar-heated steam rocket might yield decent performance if it was flown as a rockoon. The rockoon's water propellant would boil in any event if its nozzle valve was opened at stratospheric altitudes. If the rocket was painted black to absorb more solar heat, the water inside the motor would flash into steam even more vigorously when the nozzle valve was opened.Exactly! That's what I have in mind, just on a smaller (model rocket-size) scale. Speaking of scale, such steam rockets would make possible more realistic scale models of liquid propellant rockets and missiles.Thank you for posting this reference! I don't fly big rockets (for cost reasons), but I have come across articles on steam rockets (heated water, not hydrogen peroxide) occasionally over the years.I know you were half-joking there, but if someone developed a "cold" (monopropellant, that is--*not* using peroxide as an oxidizer with a fuel) hydrogen peroxide model rocket engine that would run on the 3% - 5% drug store hydrogen peroxide, I'd gladly buy one. With an appropriate catalyst screen to decompose the peroxide (say, silver-plated nickel mesh), such an engine might have adequate performance for model rocket use while being safe to use.Have you ever tried (perhaps for a small tabletop demonstration or educational rocket engine) a monopropellant engine using drug store hydrogen peroxide, and if so, what was its ISP? For model rocket use, the ISP needn't be tremendous. While I'd love to be able to buy "off-the-rack" HTP hobbyist rockets, HTP's tendency to make clothes smolder or ignite if spilled on them would make it a non-starter for model rockets, but drug store concentration hydrogen peroxide would be safe enough for general use."Have a blast in the land of America's past?" :-)