Johnny,
Dunno about the Walmarts in your area but the ones here have been carrying the Powermax for a couple of years now. They're in the camping/sporting goods area of the store. Have you checked with Wally Mart?

No I have not Tom, thanks for the heads up on that. I will try them tonight.

HI, I didn"t think anyone was useing a on board start canister any more, too dangerous. All my jets do not have on board gas canisters any more.
Rcpete

Matt, you make in intersting point that my experiance seems to suggest differently.

My line hanging in my airplane is under "case pressure" coming back to the check valve. My guess is this is around 30 to 40 psi and hot coming back to the check valve.

Are you suggesting that without the solenoid valve inline with the check that "that" is the hot pressurized gas that came loose in your experiance?

I have run the line straight to the engine, started it and not installed the check valve. This expelled hot engine gasses inside the fuse with no ill effects other than a couple of times the festo fitting inside the engine case, the blue part of it melted. Replaced the festo fitting and kept a check installed on the propane line and never had an issue after that.

FWIW.

I don't even like the liquid propane anymore RCPete.

When the P-160's were throwing fire out the front of the engine, I know someone that during startup when propane is being fed to the engine, a fire came out the front of the engine, blew through the propane line that was being fed with unlimited amounts of propane, it all caught fire and was whizzing around a fire ball out of the propane line.

After all was fixed and put back together, the same guy started the same engine and the SAME THING HAPPENED AGAIN!

I won't even use powermax anymore. Coleman with my hand on the knob, I can stop the fuel source in an instant, and I've done it a time or two.

Jetflyer 24

If I can add my support to Mr Matt. I have been using neat propane for about 2 years. Certain engines, in particular the Artes range, start noticably better. The Jetcat is a dodle. It is not affected by cold weather. It is wonderfully reliable and much less expensive.

However it is not for on board enthusiasts. I have always used a quick release going directly to the auto control valve followed by a non return (festo valve) in the model and a standard propane reduction valve followed by a Festo needle valve followed by the the other end of the quick release on a standard 5Kg propane bottle with screw valve. I find i/2 to 3/4 of a turn quite enough! I have read the pressures may be in the in order of 20bar or 250-300psi for liquid propane in warm weather compared with 70-80psi for the butane mix recommended. That is why neat propane comes in big heavy steel canisters. I once had a bird scarer explode and it cinderised the green crop for about 3 yards in every direction (fortunately no one was around). Since then I have had a profound respect for the stuff! If you want to cinderise yourself and your model - use a low pressure sytem on high pressure gas.

I think we are talking about 2 different things. Again, I think you are talking about an OFFBOARD system (correct me if I am wrong), where the pressurized starting gas is not held in the model. I am not commenting on the safety of that system with propane, other than I think it works based on my RAM experience.

What I am talking about (in terms of pressure and heat) is the ONBOARD system, where the pressurized gas system stays in the plane. I have attached a table of the vapor pressure of propane. When the onboard tank's temperature rises (nothing to do with the turbine running, I have seen this happen with planes just sitting in the pits in the sun) the propane pressure gets to almost 200 PSI when the temperature in the plane gets to 110 F. The lines cannot take the pressure and pop off of nipples or rupture.

JetCat offers a couple of features to help mitigate this. The first is starting gas dump, whereby the onboard tank is slowly dumped into the running turbine after it has started. This helps minimize the time that the lines are exposed to this high pressure.

The second feature is kerosene start, and all of this starting gas stuff is moot.

Hi Johnny:
If you would like I can see if I can ship you a case of the Power Max. Or maybe your store can just order you a couple

Dave

have you tried pure butane??
I ran my p80 with some butane i found around the house.
(lighter fluid) it was a bit fiddly getting the butane into
the onboard tank, but it started first time, on a very cold
sunday night (must have been about 0).

Dave, thank you so much for the offer. I just got home with a case of powermax ( Walmart ), trying to get all geared up for FL jets Jet-A is my next stop.



Thanks again everyone.

Matt, you keep using the term vapor pressure. Vapor pressure as I understand it is the pressure at which the gas will return to a liquid. The powermax can is under about 40 psi which will keep the propane butane mix as a liquid. As soon as you remove the pressure, it becomes back into its gaseous form and lets off heat from exansion.

Take a look at this chart:

http://www.s-ohe.com/butane.html

I don't see how the pressure inside the lines can go above 100, in this case with butane.

Maybe the mix of the propane and butane makes it go even higher in PSI, I wish I knew more about this..............

But you are right with Kero start it is a moot point.

THat chart says the same thing, the higher the temperature, the higher the vapor pressure. The chart just ends but I would assume if you heat butane over 140 the vapor pressure goes even higher :-)

Here is a definition that might help.

http://www.ilpi.com/msds/ref/vaporpressure.html


Definition
The vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor are in dynamic equilibrium.
If we were to place a substance in an evacuated, closed container, some of it would vaporize. The pressure in the space above the liquid would increase from zero and eventually stabilize at a constant value, the vapor pressure.

It is important to specify the temperature when stating a vapor pressure because vapor pressures increase with temperature. Also, be aware that there are several different units for pressure.

Finally, recognize that liquids that aren't in a closed container still have a vapor pressure. However, the material will eventually evaporate or vaporize (turn into a gas) completely.

Johnny:

Are there any Coleman Camp Stores in any of your malls near home.....the last couple of cases I bought were at the Coleman Store in the mall on the south side of St.Augustine, the last year they had FJ at Bunnell.....at that time, best prices around.....$42.00 + tax.....for a case of 12.....

Tom

Hi Matt

That's right. I do not reccommend filling your onboard tank with propane. That's just a serious accident about to happen.

Ed

TWO STORE'S THAT HAS TON'S OF POWERMAX IS BASS PRO SHOP AND ACADEMY SPORT'S.