Hi BJ
Had a few probs with fadecs one dont wanta play the game so i will take the two fadecs from my wren 200xls and try them over the week[]

What FADECS's are the 1800's running? The 'Regal' FADEC?

And what sort of problems were you experiencing?

Hopefully, you've twitched all you 'high current' cables together, and run the RPM sensor as far away from them as possible - a tip that Smithy gave me, and made all the difference.

Oh - and don't short the glowplug lead positive terminal to Earth by pushing the boot on too hard - that tends to fry the FADECS so I have been warned...

BJ

PS - you did calibrate the FADEC's to the Rx, yah?

Beej...

What is the best place for positioning the EGT Probe ?

I read somewhere that 3-5 Oclock is good , can somebody comfirm it ?

Thanks People

I wasn't aware of an "o'clock" positioning - Smithy could help clarify that - but wherever you put it, it should only poke out into the exhaust stream about 3 to 5 mm.

It may want to move around in and out a bit, depending how you've bent the thing up to get it into position - I just used a pea-sized drop of silicon sealant around the thermocouple wire just where it goes through the little hole on the outside of the exhaust nozzle to help hold it in place. The silicon breaks down under heat eventually, so I just clean it off and put a fresh lot on. I'd be interested to hear of any other suggestions...

BJ

I have read different views on this, my JJ1400 is at 9 oclock viewed from behind and my Wren Mk2 is at 6 o'clock from the glow plug.

BJ you dont want the egt probe to be able to move, it should be secured to the turbine or the turbine mount and bent in such a way that it is being sprung into the hole so it wont come out or move.

Thanks Xair - I realise that the EGT probe needs to remain rigidly fixed into position. That's why I used a little dab of silicon to make sure it couldn't budge after I bent it up a little so that it was just the right length. It's secured to the Turbine with the supplied bracket etc.

Smithy advised me to look for a potential hot-spot at 5 o'clock - the hole for the EGT is at 10 o'clock ex-factory. I'm thinking that it makes sense not to position the EGT right on any natural hot-spot to avoid getting a false (higher) ambient temperature reading and potentially causing an unwanted over-temp shutdown when the rest of the Turbine is running well within temperature limits.

BJ

Yesh  thats the idea  but these turbines dont all have hotspotes at the same place . I guess its trial and error and lots of observation whilst on test bench ..

True...

Gents,

Isn't that weird....should not the engine have an even temperature distibution if the burners, etc, are properly positioned. Shouldn't you fix the burner placement rather the temeprature probe location?

Dave

At 5 o´clock you have always the hotest point in every turbine, ( if it works correctly with no hot spots), mainly in the startup. This is due to gravity effect, and swirl of the gasses. This is the best point to know the highest turbine temperature and this is why Wren recomends to put the egt probe in this point. If you put the probe at 5 o´clock in a Jetjoe, probably you will never start it due to overheating....... take a look at "5 o´clock" on the startup.

Regards.
FĂ©lix

....and that's probably why the mount hole for the EGT is around 10 o'clock on a JetJoe....

BJ

Well there you are, mistery solved .. So 10 Oclock it is then !!

Yah...10 o'clock...but there should be a hole there to poke the tip of the EGT through already....

Hang on a minnie... have you bought a ready-assembled unit, or a kit? If it's a kit, there's basically 3 ways you can mount the exhaust cone, yah?

Go for 10 o'clock in that case...

BJ

Got a kit and will try 3oclock 6 oclock and 10 oclock

BJ do you have any videos of your turbines on youtube , if you have can you sent me link ?

Just for clarity we are looking at the turbine from the tailcone and in relation to the glow plug

Yeah , I got that thanks

All my motors I mount the probe with thin stainless brackets I cut myself . I clock near the top on the side of the rpm sensor as I run them both together on one side of the plane. I twist glow and run starter wires with it on the other side.

Hey idleup1

if you got picture to ilustrate please dont hesitate , you know what to do .. hehe :-)

I do actually have a couple of Vids of my JJ-3000 firing up - but they're pretty crappy quality. I guess I could put them up on YouTube, but I reckon I'd get bagged to the bejeezus with the usual "sh.it video... boring.... poor quality" rubbish some idiots post on there.

PM me, and I'll send them direct to you.

I'll have to alter my 'test bed' this week - the second JJ-3000 is due to arrive. I think I'll knick down to Bunnings and get a slightly larger and thicker sheet of plywood (18mm?) to use as a mounting board - and make up a base of railway-sleepers to bind it all together. Dunno where I posted it or who might have been following it, but my original test bench bolted to a standard A-frame saw-horse with a 40lb bag of cement at the base was struggling to keep just the one Turbine from pushing it over. The 'twins' would really test its mettle...

Make no mistake - contrary to the bad press JJ's do recieve - you get one that's on song and that rated 30lb thrust is pretty awesome. There's an impressive amount lot of grunt in them when you start to wick them up...

BJ

Well dont do what I did once ., wanted to see more power and kept increasing throtle until workbench cartwheeled with turbine bolted on it ..
 HEHE wasnt funny at the time cause it cost me more money !!

You will be abble to start the turbine, but never will know the real max temp on it.

Regards.
FĂ©lix

I can imagine!

And that's *exactly* the vision I had when I went for full thottle and the rear of the test-bench started lifting up and the whole thing strarted moving towards me along the concrete

BJ

Well...I'm not sure I really need to know the temp of an obvious hot-spot - it's not the real average temp of the Turbine and would only confuse the FADEC.

And it usually only occurs during start-up anyways, so the Turbine isn't under all that much stress at the time.

Sure, if it's always there once the Turbine is 'running', then I can see a problem, and it's probably time to open the Turbine up and have a look inside to see what's causing it. I'm thinking that if its already red hot at idle, it's going to cause a melt-down once you juice it up, yah?

BJ