jetnuno

Hi guys

I was just having this thought and would like to have your comments about it.

In my F18, I have 20 flights with no problems. I have an on board gaz tank installed horizontally in the LEX area. The fill valve is a one-way valve from Festo.

Everytime I fill the tank with gaz, it is almost enough for all day flying, so I do not have to worry about filling again prior the nex flight. That is the plus point of having on-board gaz.

Nevertheless I was thinking that if some day the one-way valve leaks with the turbine running, the gaz will just go CAPUUUUUN and I will have a nice barbecue to break my heart. That might happen in flight as well. Once I saw a couple of videos where that happened.

Who is flying with on board gaz and what redundant measures do you take?

Regards

Nuno

SpiderJets

Latest JetCats have an ECU option to automatically empty the gas bottle while the turbine is running.

Vincent

My Feedback: (61)

Kero start...

GSR

My Feedback: (145)

None of the above. Off board green propane hooked directly to the solenoid inlet.

jetnuno

Ok Guys

Thanks for the replies. Some comments:

I am willing to go with gaz because kerostart just wastes to much batteries and would have to buy at least 2 plugs (1 for back up just in case it collapses in the first run)

Spider Jets:
In fact the JC ECU as the option to burn all the gaz, because it just opens the solenoid gaz valve. But, if the oneway valve is damage there will be exhaust gases from combustion leaking inside the plane. REMEMBER - solenoid gaz valve is open.

I was thinking about having a manual gaz valve and keep the oneway to fill. As soon as the turbine starts, close the manual gaz valve.

Does any of you have this set-up?

Regards

Nuno

causeitflies

This is what I do...

jetnuno

BINGO

Where do you get that manual valve

Regards

Nuno

Wayne22

My Feedback: (2)

Me too... It is measurably safer not to carry around a pressurized canister of highly flammable gas during flight...

Harley Condra

My Feedback: (4)

The small ball valve is available from the JetCat online store. Part number A1013 Price $11.95

www.jetcatusa.com

causeitflies

As Harley said it is a JetCat valve, I had a few extras. Dreamworks may also sell them.
I use this whether filling the onboard tank or using the green bottle propane. I don't trust the one-way valve or the solenoid.

fast jets

My Feedback: (2)

I have never under stood why you would want an onboard tank just to dump it after start up. That small amount of fuel will not do anything to your model if a line comes off, and in a crash you have a lot of other things that will make way more flames like lipos and large amounts of kero. I have been using an on board tank in all of my models sinece 2002 and have never had a problem with it, a model that has been un flown for a month or so still has the same amount of gas on board as when I put it away. I know this because in the in the frist few model I put a presure gauge in the model and it could sit all winter and not change.

John

highhorse

My Feedback: (2)

dreamworks has some valves too...........

jetnuno

John

In fact I am not concerned about a crash, because in that event the small gas bottle might be the last of my concerns.

A while ago, I remember a jet caught fire in flight and in the event of a gas leak during flight, if it reaches the exhaust it sure will catch fire. With a filled small gas can, I only need to fill it once to fly several times and that is why I'm using it.

My concern is to have a redundant safety valve to avoid such an event and a manual valve might be a good option.

Do you rely only in a oneway valve?

Regards

Nuno

fast jets

My Feedback: (2)

Nuno


Yes that is all I have ever used, I can't see how a festo check valve could fail. I can see that if dirt get's into the valve that it may not seal all the way but I highly doubt that this would be enogh to start a fire. A model in flight has a hugh amount of air going throw it and if you should loss the start gas in flight I really don't think that you would ever know. Hay I could be wrong but I have never worryed about it at all, after a couple of thousand flights with never a hint of trouble I feel it should be just fine. I do however always run the fill and one way valve all the way to the front of the model.

John

Harley Condra

My Feedback: (4)

Off board Powermax.
Here's one way to do it.
Open both valves, start up, close the valves, disconnect.

causeitflies

It's a lot simpler to just hook up and hold the Powermax can upside down.

KC36330

IF you ever use an off board propane setup just once you'll never use an onboard setup again...................but with that being said, with the minuscule amount of PowerMax in the onboard tank, if the Festo one way failed and it dumped it's contents into the fuselage it would be sucked into the intake, combusted and you'd never know it happened.

check6ii

My Feedback: (12)

YEP!

causeitflies

Any failure of the check valve would most likely result in a gradual leak that wouldn't cause a problem unless the gas could build up in a pocket. Now if there was a major leak, like a line coming off, then there is a VERY good chance that there would be a MAJOR fire.

acw

My Feedback: (1)

Great idea!

I wonder if this could be further improved by using a shut off quick disconnect like the one we use to fill air:

http://www.dreamworksrc.com/catalog/...roducts_id=506

Festo connectors are often a pain to attach / remove. Is there any reason why using an air quick disconnect would be a bad idea? Can you guys think of a more suitable quick disconnect?

Arnaud

rcjets_63

My Feedback: (5)

I'm with Vincent on this one, Kero-start is the way to go!!!!! I hear people complaining that you need to have a spare plug ($179) with you should the one installed in the turbine ever fail (especially if you're taking one jet to a rally) but I haven't heard of many failures. Besides, take two jets to a rally and then you have a spare "everything".

Regards,

Jim

Boomerang1

Both Festo & SMC make one with a check valve built in. Both are metal & use a metal fitting that plugs in. Just plug in the gas line, start, & then pull back a spring loaded collar & the line pops out sealing the tube to your solenoid. - John.

KC36330

the only way you'd have a 'Major Leak' with PowerMax is if the onboard tank exploded. if you hook up an onboard system as you should, you install a dump valve that you're supposed to empty the system at the end of the flying day, when you open this valve the expansion of gas from liquid to gas causes cooling of the liquid and reduces the pressure, and at times the flow out the dump valve will completely stop just like when you're out in cold weather and have to shake hell out of the PowerMax can to get enough for a start.

again, you'll never know you have a leak of any size until you try to fill the tank again and when you disconnect after filling it sprays back out on you, no in flight fire of explosion.

causeitflies

And at times the gas shoots out with a lot of pressure which is enough for a serious fire. Though a leaky valve shouldn't leak this much, this is what can happen if the gas is dumped in the fuse while the engine is running:
http://www.youtube.com/watch?v=5eGWU-hVbu4

fast jets

My Feedback: (2)

Looking at that vidio it would almost seem to be more dangours with off board tanks. On the models that I had a pressure gauge installed the presure would never get higher than 50psi, if you pulled the line off the presure drops to all most nothing with in a few secounds. The on board tanks are far to small to mantian any pressure with the line pulled off, this may have some thing to do with were I live as it rarely gets to 90F in summer.

For those that prefere they off board tanks I am woundering for what reason? I like the on board tank because that is one less thing to drag down to the start box, I did go with off board tank on my Reaction andd did not like that at all.

John