Joombey

hey i have just bought a JJ-3000, its still on its way and should be here early next week. i had a JJ1200 about 2years ago and it ran not to good so hopefully the jj-3000 is a lil better, i cant hope for the best tho. neways il keep the progress posted.

Jordan

Xairflyer

My Feedback: (1)

Mine used to run no more than about 500deg with the two piece tailcone but thrust was well down than what it should be.
Once I changed it to a single piece tailcone the temps now at 160K run around 590-610deg and the thrust has increased by 3lb

HKruisman

Yes, the thrust with the 2 piece is low, about the same as with my cutdown one piece (or even less). It runs very cool though, under 600 in flight max. The other 1400 runs a lot better and about 50 degrees cooler with the same ngw, cc en cone. My compressor must be not so good

Mavrik!

So does a 2 piece tail cone produce less thrust that a single piece tail cone???

What is the rule here???

My current turbine has a single piece tail cone!

Mav

Xairflyer

My Feedback: (1)

It is not totally true that a two piece tailcone produces less thrust.

The design and parrameters of a two piece tailcone are very precise, some would say that correctly designed and made,  is more effecient but many keep to single piece just for the ease of manufacture. 

Shows how far wrong it can be, and how much an effect the tailcone has when I gained 3lb of thrust on mine.

I spoke to a very experienced Turbine manufacturer at the last Jet World Masters and he suggested to make my own tailcone and in crude terms to keep squeezing the dia of the output until I had about 650°c at max revs, and he gauranteed I would have more thrust.  I never done that but he was right as the one I have now gives me about 610 with a big thrust increase. 
I probably could get it even better but I am now getting near the 14lbs claimed and the turbine is running perfect so why bother.

i3dm

My Feedback: (51)

YES. less thrust and lower temps.

simcoeflyer

My Feedback: (1)

anyone want to sell their jetjoe to me my email is [email protected] i am interested in working or not parts etc. thank you on behalf of our science club

myring

Hi Paul,How are you? sorry for no talking with you so much long time.I have too much works to run engine even one time for a couple of months. I decide to return your ECU once I am not occupied though it was not used. Anyway I should appreciate your help.How about your job?are there any funs in your miniature turbine world?RegardsFeng Lin

gab_arm75

My Feedback: (1)

I have JJ1400 , it's have run time 7.5-8 hours, so if i like change Combustion chamber at home i need balance turbine or not?

HKruisman

No, cc can be changed without balancing. Just mark everything so that is goes back together EXACTLY the same way. Mark turbine and compressor wheel so they are the same on the axel. Also mark the axel (not needed since turbine wheel stays on it.

You can replace almost everything even the bearings without balancing. Only when you replace rotating parts or have a damaged wheel you need to rebalance.

I run the jetjoe 1400 now at 167k (169k max seen in ecu log) with a max egt of 650 when using long times of full power (2 piece cone). I have not measured the power but the difference with 160k is noticcable.

Total runtime according to ecu now 560 minutes. It has used about 50 liters of fuel now (including testing) and has almost 180 minutes of airtime. Still very happy

Xairflyer

My Feedback: (1)

You want to source a single piece tailcone, there was a big increase in thrust on mine when I changed it.

BJ64

Hmmmm... major bummer. I think I have succumbed to the dreaded "JetJoe - your RPM sensor is knackered" syndrome. How easy are these things to swap out?

I have a brand new JJ-3000 Turbine (assumingly 'factory tested') and it just refuses to fire. All goes well on initial start-up - Starter kicks in, Propane goes *pop*...then she winds back down again. Stick and Trim are calibrated as per the instructions.

But I've noticed that the RPM on the 'Monitor' was always ZERO. Having read other threads, even if you spin the engine with a hair-dryer, you should see the RPM read at least something - but nada. I see all the other prompts on the read-out - it goes 'Ready'... 'Glowplug Test'... etc... whizzz.. *pop*....dies.

I've re-routed all my wiring, and twitched all high-current leads together, moved everything well away from the RPM sensor wires, and still nothing. No read-out whatsoever regarding RPM - I think I should be seeing it at least advance a couple of thousand RPM once the starter kicks in. But nup - jack she-ite. Maybe it's the FADEC - but then it wouldn't go through the start-up sequence, open the Propane, juice the plug and 'light off', would it? The Propane definitely ignites...I can hear it, and feel the heat afterwards. But no RPM readings anywhere along the line.

The 'Combo' I've got is running a 'genuine' JetJoe fuel pump (blue thing - 20mm diam by about 50mm tall), Regal FADEC, and JetJoe solenoids (brass fitting, yellow windings). Fuel pump/solenoid work coz I've managed to purge the kero lines no problems.

What is s a bit discrening however is that I noticed that the Propane solenoid doesn't always shut-off properly (dead 'Bad Start', close the gas valve, and when I turn the bottle valve back on, I can hear the gas injecting into the Turbine - no real worries for me, as I manually control the main gas valve anyways). I have that timing right, coz as soon as she tries to spin up, I open the the bottle valve and she lights. It worries me a little that the Propane solenoid can open (or stays open) before the FADEC calls for it. No big deal just yet, as the whole thing is on a test bench and being fired out in the open- I'd hate to think an airframe was filling with Propane before I initiate the start sequence - any aircraft with a belly full of Propane is gonna go ~POOM~ when the glowplug kicks in.

I've checked and double-checked my wiring etc. It's all 'by the book' so far...

Any ideas?

BJ

i3dm

My Feedback: (51)

BJ,

Try to reverse the RPM sensor plug in the ECU connection. the connector might be in backwards (even if the wiring colors seem right) ?

BJ64

Thanks id3m - I've thought about doing that, but I wasn't sure if I'd end up 'busting' something - not so much the Turbine, but maybe the FADEC? Some things like Solenoids etc don't really care about which what the current comes in - if it's there, they actuate. If it's not, they don't.

But, from reading around the traps, there's a few "do's", and a lot of "DONT's" when it comes to the FADEC. Like short the glowplug lead on a JJ, and the FADEC becomes a fancy and light paper-weight pretty quickly. Not knocking those that make FADECS, but surely there's a few electronic 'tricks' around these days that could bullet-proof a shorted lead. It ain't exactly rocket science.

Back to the RPM Sensor - it's basically a magnet that spins on the rotor shaft across a 'Hall Effect transistor', right? Regardless of what it is inside the beastie, there must be something I can do with an 'Industrial Grade' multi-meter that can at least hint to me whether that thing is working or not. Granted, I know I'm not getting a read-out on my monitor, but that doesn't necessarily mean that the Sensor is stuffed. Maybe there's some resistances I could check....?

BJ

i3dm

My Feedback: (51)

thinking about it again, the connector that is easy to put in reverse in the EGT sensor, not the RPM.

try to degauss the sensor by running a powerful magnet around the front cowl of the turbine and see if it makes any difference.

you can also open the turbine cowl to check if you have a loose connection in the RPM sensor. you will see it mounted on a small PCB under the hood.

BJ64

Kewl - I might just try that. I think removing the cowl is still permitted under 'warranty'.

I've read on other threads that Customs use pretty powerful stuff these days and whatever they do might stuff the magnet up. After all, ye olde Hall Effect requires a correctly polarized magnet for it to be able to sense the pulses.

I'm a bit reluctant to open my Turbine in any way at the moment though - if I do something wrong in doing so, I can kiss any warranty goodbye...

BJ

Xairflyer

My Feedback: (1)

Very easy to take front cover off and check rpm sensor, normally if it reads zero then it is plugged in the wrong way.
I never use the gas valve and I always use external gas and turn it off myself once I see 25K during startup, I then half a one way valve (check valve) on the gas line which seals it one I remove my gas can.
Gas valve only needed if you want on board gas.

BJ64

Thanks Xair. I might have a peek under the cowling then.

But if it's only a matter of the RPM sensor being 'plugged in the wrong way', couldn't I acheive the same thing by just plugging the RPM sensor lead into the FADEC the other way around? Or has it got more to do with the Hall Effect transistor versus the Pulse Magnet orientation?

Either way, the Turbine was supposed to have been 'test fired' before shipment - surely it wouldn't have worked for them either if the RPM sensor was the wrong way around?

BJ

HKruisman

2 things:

RPM sensor (banana style) is very sensitve and ANY dirt can make it stop working. I had the same problem. Take it out, take off the shrink wrap and clean it. Mine worked fine then. Also theck with another magnet. When not absolutely positioned it can misread or not read at all.

When you short the leads (glow / starter) on the fadec you can repair it yourself The fadec has a thin wire strip on the surface which acts like a fuse. When you shortout the leads (done that myself) the fuses burns and protects the circuits. Just open the fadec and theck for any burned traces (fuse trace is on the side). I have another fadec with damaged to the fuse trace also due to a bad starter motor.....

My motor has a ngv that is just a little to small. I noticed the turbine wheel rubbing the ngv. I cleaned it up and rebuild it and it looks fine again. Rear bearing is in excelent condition, even at 167k rpms Wren ngv seems to hold it very nicely. A few hot spots but not a real problem. CC looks ok and has even burn marks allover.

HKruisman

Rpm sensor can only be plugged in 1 way (and work ) Theck the colors on the fadec.

Xairflyer

My Feedback: (1)

I have the gasper ECU and the rpm sensor can be plugged in the both ways, the label shows the colors ok but it still can be done.
Another thing I thought about is, it is very easy on the gasper ECU to mix up the EGT and RPM positions on the ECU as one is above the other and depends on which way you look at the label. Same goes for the fuel and gas valve as I had these the wrong way around myself in the early days. Maybe the regal ecu is more clear.

Xairflyer

My Feedback: (1)

I took the heatshrink off my spare RPM sensor and took some pics so you can check the wiring etc.

You would probably be quicker to get a replacement if needed from [link=http://www.xicoy.com/catalog/product_info.php?cPath=22_25&products_id=73]Xicoy-Gasper[/link] only about 20 euro

BJ64

Thanks again guys.

The Regal FADEC is pretty straight forward where things have to be plugged in. I've checked and double-checked everything, and it all looks like it's in the right place.

I simply don't get any RPM readout on the Monitor - I get the 'Lo Stick!', 'Glowplug Test', 'Start' messages, the starter kicks in, the Propane lights, and then it dies in the @rse. I kept a close eye on the RPM readout during startup, and it never budged from all Zeros.

Not really sure what else to do, but I'm guessing the RPM sensor is cactus...

BJ

HKruisman

Check and clean the sensor, check the magnet en try the sensor in a different place when spinning the rotor. If it stays 0, buy a new sensor

BJ64

Hey guys - I think I've got it sussed out now

My original problem was that I had the RPM Sensor lead mixed in amongst the high-current leads to the Starter Motor and Fuel Pump. I couldn't get a decent start this way, and it was suggested to me that I was probably picking up stray RPM spikes from the high current wires.

I've now made sure all these wires were twitched together, then re-routed my RPM Sensor lead so that it was more or less out on it's own - well away from any other wiring. On my Turbine, all the leads are relatively short, so to get the RPM Sensor lead free of all the other wiring, I bought an 'extension' lead.

I've just been outside in the 'Dungeon', and rechecked everything again. The RPM Sensor extension lead that I bought has little tab on one side - just big enough to allow the RPM Sensor plug to go into the FADEC one pin too far to the left (there's *just* enough room in the FADEC socket to allow it to do this). So I flipped the connector over, and switched the other end as well so that the Brown wire on the RPM Sensor lead matched the White wire on the extension lead, and the White wire from that matched the Brown wire's pin in the FADEC.

Problem solved - I now have RPM readings again when I spun the Turbine up with the help of a little compressed air and I double-checked that I get an EGT reading from the Thermocouple as well.

Now all I have to do is wait for my balanced battery charger to arrive so that I can get some more juice into the LiPo and hopefully a NOISY start

Thank you all for your input - there's always something new we can learn.

BJ