Personally I would be very careful with that technique. As long as you are on the ball it is fine but if you are a bit slow and open the tap a bit late you risk an overtemp.

As Pete says, the ECU shouldn't pump fuel if the gas doesn't raise the temp beyond a pre-set limit. If the gas doesn't light, the fuel shouldn't flow.

oops

And, if you forget to open the fuel shut-off valve before attempting a start, which I've never done [sm=red_smile.gif], immediately abort the start. If you open it after the pump has started the ramp and is now trying even harder to build up pressure, and suddenly release it, you are sure to get flames and an over temp with the sudden dump of fuel.

Pete, The Kero solenoid would still open but it don't know that you have the manual valve off. All the ECU wants to see is that the solenoid did open. It's up to you if you have the manual valve open or closed. It all happens in a matter of a Sec or a little more. Your fuel line is full and when you cut the valve on yourself it's right there in your turbine. Now-I don't know if every ECU is like mine. Mine is a modellbau. Your ECU is not going to send a fuel pump on Sig until it sees the right EGT. The gas ramp up does that. It has never failed on mine. Try it sometimes. Put a valve inbetween your solenoid and the turbine and don't cut it on intil you hear the gas light off, then cut the valve on. I have never had a hot or wet start. if you miss the cue and the jet-A don't make it to the combustion chamber than your RPMs and EGT tells the ECU not to cut on the fuel Solenoid. It's fast matter of timing. Your cue to hit the valve is the gas pop. Let me know how it works for you.
Hooker

I have never done that either

georbeckha

What were the results after talking with the folks at Jetcat? Are you still running your fuel pump filter on its side like in the pictures of the Shock Jet? I think they recommend mounting it vertical to eliminate any air that could get trapped. I am interested in learning what is causing your overspead and overtemp problems.

MACE

Mace,

The first time they said that the speed sensor magnets got demagnetized so it didn't know exactly how fast the engine was running. This caused the shaft to bend and the result was the destruction of the engine, flames and a little singing of the wood.
The pictures up there are of the rebuilt engine doing pretty much the same thing, but this time the flames took hold.

In the picture attached here you can see a white patch in the middle of the runway behind the model. that is where it come to rest. Probably my best landing job so far with the ShockJet. It's amazing considering I was yelling to the peanut gallery that there was a fire and they just sat there watching (They say they didn't hear me) and I was watching the flames eating my plane.

The Filter I have in line was actually standing upright. I think it got twisted around when the fuel line got pulled tight when the engine seized and torqued around.

George

Pete, i would just run it the way the scematic depicts......Should work great!

I hate engine fire. This was the aftermath of my first and only engine fire about 8 years ago.

My airplane went from this:



to this:

You should have had one of these.... [link]http://www.speedfreaks.net.au/index.php?page=shop.product_details&category_id=10 &flypage=flypage.tpl&product_id=103&option=com_vir tuemart&Itemid=1[/link]

That says it all, quite agree.

Do any of you use any form of heat protection on the inside of the fuse where the thrust nozzle is? I would imagine the area around the nozzle and tailpipe gap must be the hottest. I used some heat tape over my servo leads.

Thanks! Pete

BVM

Has ceramic heat paint that works great. My friend also uses automotive high heat insulating sleeves to run his wires in that area.

I should have asked if it is even necessary to prep the fuse for heat from the turbine. Wouldn't something like that be provided in the ARF if it was an issue?

Thanks! Pete

As afar as the valve goes, i like to install it before the pump as well, for the same reasons mentioned here.

The problem with putting the shut off valve between the UAT and the pump is that the valve can act as a restriction which the pump must overcome when the turbine is running in normal operation. The restriction can lead to cavitation and bubbles being created in the fuel line to the turbine. The small Tetra valve provided with JetCat engines certainly is a restriction, but it is installed on the 4mm output side of the pump. A 6mm Festo 1/4 turn ball valve provides little restriction and can be installed on the inlet (suction) side of the pump. However, make sure that the Festo seals properly as any leaks will result in air being drawn into the suction line to the pump.

If I had to shut down the turbine due to a fire, I would do it using the transmitter shutoff (closes both the fuel solonoids and kills power to the ECU) rather than reaching into a plane that is on fire and I may or may not be able to see the flame in/around the shutoff valve. Of course, but this time I've already given it a shot from the extinguisher.

Good call Jim!

That's probably why JetCat recommends their valve after the pump. I always use the 6mm Festo ball-valve between the UAT and pump thus providing the least restriction. There is already a 6mm line coming from the UAT and some pumps already have the larger diameter inlet nipple, so it's a very easy set-up. And yes, make sure the line is fully seated in ALL Festos.

So would I!!. The 2 reasons for the manual valve, as far as I can see, is that you prevent the engine being flooded when refuelling and so that you have the means to shut off the engine following some form of ECU failure that leaves the pump running. It is a last resort shutoff only if the TX shutoff doesn't work.

Agreed. The pressure generated in the fuel system when refueling the plane certainly is great enough to push fuel past the fuel pump. Come to think of it though, between the fuel pump and the engine is the solonoid shut off valve and that would stop the engine from being flooded.

Assuming that the solonoid valve doesn't leak through, that would leave only one reason for the manual shutoff, it is the last resort.

Correct me if I'm wrong here, but I think the AMA requirement for a shutoff valve is met by the solonoid valve and there is no requirement to ALSO have a manual valve. Either way, I always install one (just in case) and it is ALWAYS closed when I refuel.

This straight from the AMA 510-A document:

8. ... The fuel system shall have two fuel shut-off provisions, one of which is manual and the other one must be remotely operated. An ECU operated shut down is compliant as a remote shut-off if it closes with loss of power.


If the ECU is compromised, it might not have the ability to de-energize the fuel solenoid. Also, as most of us have found out, the solenoid by itself won't necessarily prevent fuel from being pushed passed it and into the turbine while fueling.

The Australian rules for turbines require a radio controlled method of shutting the turbine down independant of the ECU as well as a manual shut off valve.

I use this arrangement to do both jobs.

The servo is also set up with the failsafe to shut the fuel valve.- John.

One more jet fell victim to an engine fire yesterday []

[:@][:@] Sorry to see that! [:@][:@]

What happened?

John

Its the same in the UK and most of Europe. I use a manual festo valve before the turbine. On my on TX either pulling the trim down or loss of signal and switching off the fadec will kill the pump. In addition, I use a one way switch to the pumps power lead, so by servo in the air or by hand on start up in the pits, I can kill the the pumps power instantly. The switch is one way to be manually reset only. It looks as if this type of setup might have saved some models becoming crisp and well done.

Paul

An independent radio controlled method of shutting down the engine is not required in the UK according to BMFA or JMA. Curiously the BMFA require a manual shut off valve or fuel pump isolation switch whereas the manual valve is only a recommendation according to the JMA.