Ok, I'm working on an Estes Stiletto, and I'm aware of its cold power predecessor the Estes Shark (1111).

I've read the instructions and located info on the body tubes, and I'm a little perplexed.

I though that the Stiletto was only a 3FNC (actually 10FNC) standard rocket based on the Shark's 4FNC (actually 13FNC) layout. However, the Shark's body tubes combine to only be 13.5" long, and the Stiletto's single body tube is 16" long.

Was the Shark really 2.5" shorter than the Stiletto?

I know that I wouldn't be able to build a cold power rocket as the propellant was a little harmful to our ozone layer, but I am thinking about cloning its exterior.

Thanks!
Jim

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Dreaming of making the rockets I dreamed of as a kid (and then some).

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"The knack lies in learning how to throw yourself at the ground and miss."

Launching is Optional... Landing? That Depends on Trees.

Dug a little further, and I found that the catalog lists the Shark as 19.5" long, and the Stiletto as 22.4" long. So the Shark IS shorter than the Stiletto.

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Dreaming of making the rockets I dreamed of as a kid (and then some).

"The Guide says there is an art to flying", said Ford, "or rather a knack."
"The knack lies in learning how to throw yourself at the ground and miss."

Launching is Optional... Landing? That Depends on Trees.

Probably had to do with the way cold power rockets "ejected" the chute...

They used paper "timing disks" to create a "calibrated leak" at the head end of the motor (propellant tank).

During "fueling" (filling the propellant tank with freon) the pressurized gas would leak upwards through the paper disk and act against a small "bellows" (basically like the vacuum modulators in a car that open and close the heater/AC ducts to direct air to the floor, vents, or windshield depending the position of the vacuum switch). The "bellows" would then push out a pair of arms against spring tension (that pulled them inwards) to hold the parachute section to the top of the rocket against spring tension (that was trying to push it apart). The ejection section had to be held in place until the motor was pressurized enough for the arms to hold everything together due to motor tank pressurization. The remainder of the liquid freon propellant would be injected into the tank, and the fueling tube removed, ready for launch.

At launch, the plug in the nozzle would be ejected by a pull pin or burn wire holding it in against motor pressurization. Once the plug blew out, the liquid freon was squirted out the nozzle and instantly began boiling in the tank due to the loss of head pressure and latent heat of evaporation in the tank and freon itself. The freon squirted out the nozzle would boil instantly into gas, expanding out the nozzle, and creating thrust. The boiling freon in the tank kept self-pressurizing the tank sufficiently to squirt the freon out the nozzle, until all the liquid freon was expended and the tank was empty. At this point, the remaining pressurized gas blew out the nozzle, and the motor "burned out" (so to speak-- quit thrusting is more correct). The loss of pressure below the paper disks then allowed the pressurized freon gas in the bellows to leak back down through the paper disks, giving a "delay" as the time elapsed for the gas pressure in the bellows to leak out through the paper disks (determined in advance by how many paper disks were inserted into the top of the motor tank connector) which provided the "coast" phase of the rocket flight. When the last of the pressurized gas leaked out of the bellows through the paper disks, spring pressure retracted the arms holding the interior of the parachute tube and a spring would separate the two parts, allowing the parachute to "fall out" and deploy...

SO, basically a cold power rocket "split in the middle" and had *some* amount of tubing in front of the motor tank cylinder itself, for the parachute compartment... might well explain the difference the rocket lengths...

BTW, folks have flown cold power rockets in an environmentally benign way-- instead of using freon (cost prohibitive and "illegal" to release to the atmosphere) use canned air for blowing out keyboards and stuff for propellant. Works pretty much the same.

Propane would also work, but of course there's a short period of danger of it igniting...

Later! OL JR

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Great explanation of the Vashon rocket operation!
The Cold Power Convertibles were different, the engines were smaller in diameter and fit into a BT-50 body tube. You didn't have control over how many of the "timing disks" were used.
The Cold Power models also had a coiled spring that pushed out the parachute instead of the older Valkyrie deployment that just released the aluminum tube holding the parachute.
http://oldrocketplans.com/estes/est1111/est1111.pdf

I remember not being able to display the Shark without that spring sticking out the top of the model.
The instructions say you could remove it for display but I don't remember it being that easy to remove.
Altitudes were never great, about the same performance as a B6-4 engine in that size model.
If it was cold, you'd be lucky to get it in the air! I converted mine to standard BP engines.

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Hans "Chris" Michielssen
Old/New NAR # 19086 SR

www.oddlrockets.com
www.modelrocketbuilding.blogspot.com
http://www.nar.org/educational-reso...ing-techniques/
Your results may vary
"Nose cones roll, be careful with that."
Every spaceman needs a ray gun.
Look out - I'm the Meister Shyster!

You can actually use R-134a refrigerant from the auto parts store to 'fuel' the 'R-12' old cold power 'engines'.
By the way, it has been proven that like most all 'enviro-whacko' causes, the R-12 supposed damage to the ozone layer was WAYYYYY over-blown.
Chloro-Fluoro-Carbons have far less impact than the propaganda puked upon the general public by the enviro-whackos.
The proper and prudent response to the R-12 issue as well as all other enviro-whacko 'farces' is below:

HUFF a LARGE vat of Jenkem !

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

I tend to agree, but considering the world we live in now... LOL

Later! OL JR

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