I haven't heard anything from Rick Piester one way or another regarding bringing back the Cold Propellant and/or Cold Power Convertible model rockets. It is possible that Estes no longer has the tooling to produce the motors.

However, at the very least they *would* be able to re-issue the Cold Power Convertible kits (Yankee-5, Shark, Teros, Scamp, Marauder, etc.) as regular 18 mm black powder motor powered rockets. (Estes did, in fact, sell the Teros and Scamp kits as "ordinary" rockets for several years.)

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NAR #54895 SR

Ah, thanks for the info. I went back reread the first post and see that this is more a general, what kits would you like reissued, rather than a, we're considering bringing back cold power. Still, it doesn't hurt to ask.

I had one Convertible model way back when. I think it was a Marauder. After the nozzle broke off of the cold power engine, I converted and I guess I lost it on a black powder flight at some point, because I certainly don't have it any more. Toys 'R Us stocked them back then.

The opposite arrangement (a black powder first stage and a longer-thrusting, lower-thrust Cold Propellant second stage or "sustainer") could yield a very high-performance bird. I don't know if Estes would want to get into such new product development (at least right now), though.That would provide useful and versatile capabilities.Just "thinking out loud" here, in the NASA Wallops Island history book by James Shortal ("A New Dimension"), there is a short section on an educational steam-powered rocket (about 2-1/2' to 3' long) intended for school use that 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 terribly unlike a great big Valkyrie motor) that powered Evel Knievel's Sky Cycle in which he attempted to jump the Snake River Canyon in 1974 (its recovery parachute opened somewhat prematurely, but the steam rocket motor worked just fine). An updated version of Admiral Truax's educational steam rocket would have interesting possibilities.

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Been following this thread for awhile waiting to see if anything is coming...

I had a couple of V-1's, they were extremely cool. I used to use my Estes launcher (12 volts) to launch them with the bimetallic wire, as well as my black powder rockets. Been looking at this as an experiment, with different fuels, and some kind of small PTFE plastic bottle as the engine (alas, my Vashon engines are long gone...)

R134a isn't gonna happen, you can't vent it into the atmosphere AT ALL. The only exemption is for very small quantities, typically for medical inhalers where they need a non-toxic and non-flammable propellant. It's the only one left. N2O might work, but it has a nasty habit of reacting violently with anything reasonably metallic/reactible, and it has a vapor pressure of about 60 bar (vs. 6 bar or so for R-12). That's why it works so well as an oxidizer for hybrids. Diflouroethane (R152, "canned air") would be a reasonable substitute, the regulations for its release are somewhat vague and it is is wide use as an aerosol propellant so the miniscule amounts that us hobbyists would be using wouldn't amount to a hill of beans. HC's (propane, butane) would also work, but I doubt that the CPSC would look kindly at it, nor would the NAR/Tripoli people. Forget about compressed gasses like CO2, N2, etc, they're just too difficult to work with and you'd need very high pressures (> 100 bar, most likely) to get decent performance since they have much lower densities.

There have been some people out there playing with canned air rockets made of out Sharpie pens, etc., Google/YouTube it. Looks like fun. Anybody tried this on a bigger scale?

One of the biggest problems with cold-power in high humidity areas is nozzle icing. You have the same issue with CO2 powered aircraft engines. Also the difference between wet and dry charges. Although - it would be rather nice to have an Atlas that really frosted in the right palces...

P.S. Commercial airliners at 40K plus trundled transtlantic for the last 40 years - in the Summer the high latitude routes place them within inches of the Arctic circle. Even now Concorde at cruise has a smaller "carbon footprint" than any subsonic aircraft in the air with the same route. The Ozone argument was a political expediency to prevent a "not built here" aircraft from dominating a market segment. It was the issue that cooked the Comet. DH lost two Comets to stress fractures because in 1952 no one fully understood the expansion cycle issues of pressurised cabins. Boeing read the DH research rounded the windows and buried the Comet in a sea of press even though the 707 went into service six years after the roll out of the Comet. Still and all, 707s would routinely drop engines. Also interesting that the only Concorde lost was caused by a DC-10 part - conspiracy theory anyone? Bueller? Anyone?

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Gravity is a harsh mistress
SAM 002
NAR 91005
"The complexity of living is eminently favored to the simplicity of not."

Thank GOD I dont live near a coast. Got enough flakes moving here as it is. I think they should kick it up a notch and make small fusion drive motors. A little deuterium .............

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Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc - Starfighter Scorpion Centuri - Mini Dactyl Estes - F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc - Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark

Nitrogen and Propane come to mind.

Dave F.

Liquid nitrogen has to be very cold (cryogenic cold) in order to be liquid, and propane is flammable. But, just as "inerted hydrogen" (a gaseous hydrogen/nitrogen mixture [95% N, 5% H, if memory serves]) is used for gas line leak-detecting purposes, propane might be mixed with one (or more) inert elemental or molecular gases, to make it effectively non-flammable while preserving its relatively high-temperature and low-pressure (as compared with nitrogen) transition from a gas to a liquid (which of course would be reversed when the Cold Propellant or Coldpower Convertible model rocket was launched).

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

A factor that affected the Cold Propellant and Coldpower Convertible motors (it also affects black powder and composite [solid] propellant model rocket motors, but not to nearly the same extent) is the ambient temperature; the Cold propellant motors work better on warm days, and less energetically on cool or cold days. The Vashon Industries catalogs even recommended to--on cool days--hold the fueled rocket in one's hands in order to warm the fuel, so that its internal pressure (and thus the thrust) would be higher. Also:

I never had a Coldpower Convertible motor (its plastic nozzle/launcher lock-down *does* sound like a weak point, especially when the plastic is cold and more brittle), or even a Valkyrie 1 or 2 motor (their plastic nozzle skirts--I saw an Estes Valkyrie 2 Starter Set in a Titusville, Florida store in 1975--were made of a softer plastic, like Delrin, and they were easy to replace if necessary), just the aluminum motor (the XR 100) that powered the Estes Land Rockets (their rocket cars: http://www.ninfinger.org/rockets/no...a/76est044.html ) and also the Shrike and XS-1 Space Shuttle (see: http://www.ninfinger.org/rockets/ca...73/73est44.html ) rocket planes. (Incidentally, the Estes Sandpiper scale model [see: http://www.ninfinger.org/rockets/ca...74/74est44.html ] was originally a Vashon kit, as were the Valkyrie 1 & 2 and the Baron, Astro-Gnat, and X-13 parasite boost-glider kits; the Sergeant may also have originally been a Vashon kit.) But Vashon's tip worked; holding my Screamin' Eagle car's motor after fueling it on cooler days increased its thrust (and the car's acceleration) over what it did if I didn't warm it up first, and:

I'd love to see Estes--or another interested firm (Quest?)--produce updated V-1/2 (for first or upper stages, and strap-on boosters), V-1, and V-2 Cold Propellant motors, perhaps with a different pressure sensor to activate the recovery (or separation) system, although the original paper discs adjustable-delay system seemed to be perfectly practical. Plus:

The V-1/2 motor (or the smaller XR 100 motor) could be used to make an Estes Falcon-like *rocket glider* (RG), of the "propellant burn-off, weight-shifting" type (which has no moving parts or control surfaces). The fueled motor, on its forward pylon (with a nose cone, but no separation or parachute activation system, on the motor) would make the RG nose-heavy, and thus a ballistic vehicle. After its cold propellant was expended, the model's Center of Gravity would be shifted rearward (and its total mass would be reduced), making it glide.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR