Got a "Napier Gazelle" but need help

[turbochris]

yeah disconnect sw very important. Is the starter the generator too? Did the turbine need a soft start?

[TwoGears]

I'm sorry for my late reply but my friend I have got the workshop with took the
key with him to his holidays so I had no chance to get to the turbine until today.

@curorkeys
I remounted the starter just in case you're right because I don't really know much
about it. Save is save I guess, more or less.
Unfortunately I must answer with "no". I have almost no sheets about this engine
except the drawings and partial cross sections off the links a few posts above.

I didn't take the inductors apart but it seems cored. Otherwise it won't make much
sense to create two power lines where the second stage is delayed with a timer.
I'm pretty sure it's for some kind of soft start or peak-current cutting.
I'll try to measure the inductor these days to calculate it's values.

You were right. K4 really is an Albright SW200. I'll have a look if I can get a second
one somewhere for K2 replacement, since I'll rewire the whole thing. The former
owner really produced a mess there. I'm also thinking about using more modern
power switches and relays.
Also thanks for the hint with the 500A MegaFuse. This thing will make a good job
in case of emergency.

turbochris
I also got a disconnection switch from a truck which shortly can handle shut-off
currents of 1250A. This plus an emergency bolt cutter hopefully will save everything
and everyone from any harm

The starter is just to start the turbine. It has a normal centrifugal gear which
is knocked back when the turbine speed exceeds the speed of the starter.

Unfortunately I don't know any of the working conditions of the turbine. The former
owner had no idea on how to connect the starter box and the turbine, that's why
he sold it.

[TwoGears]

Update:
Yesterday, after disassembling the complete starter, cleaning and
reassambling, the turbine finally had the first spin-up (just with the starter).
Well I can say everything works like charm so far.

Before I'll proceed with a full run now. I need some informations
on how to start the turbine properly. I know the basic startup sequence
but I'd prefer to have some more information.
I'd be glad if someone could give me some advice on this.

Thanks in advance

[ernie wrenn]

Be sure the starter comes to a complete stop before reengaging. The starter drivers are a little weak and will break.. very expensive..

[cursorkeys]

Oct 1, 2013 5:35:24 GMT -5 TwoGears said:

Update:
Yesterday, after disassembling the complete starter, cleaning and
reassambling, the turbine finally had the first spin-up (just with the starter).
Well I can say everything works like charm so far.

Before I'll proceed with a full run now. I need some informations
on how to start the turbine properly. I know the basic startup sequence
but I'd prefer to have some more information.
I'd be glad if someone could give me some advice on this.

Thanks in advance

Glad it's going well! Ernie's advise on the starter is gold BTW, know one person who sheared a starter shaft like that.

Do you have instrumentation sorted? The big three would be EGT, RPM(s) and oil pressure. I'd say you defintely need the core engine RPM (Ng/N1) and the free-turbine RPM (Nf/N2) as there could be a fault with your free-turbine overspeed limiter and just looking at Ng it would be hard to spot that. I had a fault on my GTD-350 where the limiter decided to fail open and a few percent past where it should be on the gas producer was enough to send the free-power to about 110%...scary.

Assuming you have instrumentation all set up I'd do the following checks (make sure to leave lots of cooling periods for the starter as lots of cranking is needed).
I'd also put an emergency manual valve on your fuel supply so you can definitely cut fuel to the LP fuel pump quickly if necessary. Cavitation can damage the fuel pumps but that's probably better than the alternative.

1. Check some oil pressure is seen when motoring the engine.
3. Connect fuel.
2. Check the HP cock operates by ensuring the ignitors are disabled and then cranking the engine with the HP cock open while looking for a kero fog out the exhaust. If no fuel is seen then move HP cock to the other position/check for fuel bleed points on the engine. If still no luck then resort to cracking fuel lines and seeing where the fuel is
3. If there are any combustor drains check they are draining fuel from the wet cycle(s).
4. With the HP cock closed motor the engine as many times as necessary until the engine is 'dry' again (no fuel spray/dribbling/mist visible from the exhausts when cranking).
5. Re-connect ignition system.
6. Attempt a light-off with the throttles wire-locked in the zero positions
7. If the engine lights then attempt to stop the start using the HP cock (to ensure it's in working order!)
8. All Set! Attempt to get to idle. If any of the engine parameters are exceeded then abort the start using the HP cock.

That's the way I'd write a safe procedure for someone else

[TwoGears]

~~ It's alive! ~~
Thanks to your help guys, my turbine finally had her first run.
It was awesome although it was very short since I have discovered
some problems.

1.) There is way to much fuel coming from the combustion chamber
and I don't have the slightest idea why. Throttle is completely down to
idle-speed and for the cut-off handle there are just three positions
so far (ON, OFF and some kind of LEAD-THROUGH-OVERFLOW). I dried everything
and started again but the same problem as before. Huge flames and a lot of
fuel dripping out of the exhaust tubes.
Both tries I ran the turbine with idle speed, which seems pretty ok to me.

I'm still not sure what the third handle is for. But it's on zero so there
shouldn't be any problems with it.

I also experienced that I have a, HP-pump controlled, handle which changes
the angle of the static inlet blades. I don't know if this has anything to
do with this problem but the scale shows 40deg and I didn't have a look if
it changes while startup.


2.) The second and maybe more problematic thing is, that I have
suddenly experienced a, more or less, huge increase of oil in the tank.
First I feared there is some leakage where fuel is entering the oil circle
and pumped back. But when I tried to burn the oil it didn't really react until
it was very very hot, except of some sparks. I think the sparks came from the
old oil.

I also tried pure fuel, which burned immediately. Then just oil which also needed
a long time until it became very hot and burned. then a 50:50 mix of fuel and oil
which also immediately began to burn.
Is there any method to find out if fuel has entered the oil cycle?

Still I'm not sure where the increase of the oil level is coming from. Therefore
I fear to run the turbine again.
Any ideas on this?


...Thanks for your help

[turbochris]

scavenge pumps not working?

[gidge348]

I think it is reasonably unlikely that you are getting fuel in the oil, there should only be a few places where they even get close to each other. I had a similar thing the first time I started my nimbus and it turned out that while the engine was sitting, the oil drains out of the tank and into the lowest point in the gearbox. Then when you start it the scavenge pump picks it all up and dumps it all back into the tank.

The fuel on start up may be a symptom of a hung start.

Turbines are a scary thing to start up and we tend to disconnect the power too soon. Make sure you have good batteries and don't turn off the starter until you have reached the specified idle speed.

Sounds really promising though.... Might be wise to find out what the additional lever is for even if you play with it on a dry start up.

[cursorkeys]

Congratulations!...Do you have a video? There are no vids of these engines running on the web, I'm dying to see yours run

I agree with Ian on the oil, I've seen an Artouste (freshly charged with oil after transport) do this to the point where oil was pouring out of it after the run. If it was that badly contaminated with fuel you should be able to detect it visually or by smell. The second run would be the charm, if the oil level is static then there isn't a problem.

If you really want to get the oil checked for fuel then any aviation servicing company should be able to sort that for you, a quick Google search threw these guys up who say they do a by-post service to a local lab:

www.alsglobal.com/en/Our-Services/Industrial/Tribology/Capabilities/Aviation-Oil-Analysis


On the 'hot' start what EGT/TIT were you seeing? If it was below the specified max starting temp then it may just be that it was a seriously early engine. Are all your compressor bleeds closed/blanked off? Are your batteries/wiring capable enough (was the starter slow)?



I've found that a tractor pulling team were using a Napier Gazelle in one of their tractors "Le Coiffeur III". I guess they would know about the engine controls: www.le-coiffeur.info/wordpress/en/

[cursorkeys]

You can also try opening your HP cock after the engine reaches, say, 10% on the starter. That might help if its just that the fuel controller is a little too eager at low RPMs.

[gidge348]

Agree with Jon.... This is a beautiful & unusual engine, I would love to see a video of it running.

The excess fuel on start up may just be the way they start, they did not have environmental issues to worry about back then

Have a look at minute 2.50 of this 1950's turbo jet starting www.youtube.com/watch?v=wRH0eDrNjSY

Try and get to idle as quickly as possible don't let it sit at 10-20%, if you do..... and you get a hung start, it will just sit at low rpm, no throttle response and get hotter & hotter until serious damage occurs. If things start to look like this shut it down, let it cool and try again.

Do you have details on temp movements, oil pressure, %rpm during the run?

Ian...

[TwoGears]

Hello guys!
I'm sorry for my late reply. Thanks for all the constructive suggestions
on what could be or isn't either, wrong with the Gazelle.

Since I'm quite busy at work this week I can't go to the workshop
and give it another try, although it's burning in my fingers and I think
more about the turbine than anything other 
I guess it couldn't be helped. We'll have to wait for the weekend.

Just a few points:

• EGT/TIT:
  As far as I remember the EGT stood a 600°C when I shut off the engine.
  Unfortunately I don't have any option to measure the TIT yet.
  I assume it was a hot start.
  
• RPM:
  Since my tachometer for measuring N1 is broken I can't give any information
  about that either. The only thing I know is, that the turbine turned up slightly
  higher in spin, after igniting, and therefore I shut off the starter and thought
  this was idle speed. Now I'm not sure if it were or the starter-batteries just
  didn't have the energy to spin the turbine up to ignition-speed.
  However, two attempts and both times a huge amount of fuel dripping out the
  exhaust cones.
• OIL:
  I'll have a good look on the oil level when starting the turbine again at coming
  weekend. In my mind I've gone through the path the oil and fuel takes and I
  think you're right. There isn't really a place where both could come together
  so close the fuel could enter the oil circle in such an amount.
  I'm looking forward optimistically.

Also thanks for the links to the YouTube video and the Le-Coiffeur page.
I wrote those guys for informations on their Gazelle and keep you up to date
on it.

Again, thanks for everything so far. I, no WE will make the Gazelle run soon,
hopefully coming weekend

[gidge348]

Don't forget the video

[gidge348]

EGT at 600 seems fine as long as it wasn't climbing with no difference in RPM

No rpm measurement can be a problem even if you go to a local electronics store and pick up a optical Tacho would be better than none. Do you know the specified RPM at 100% and then work back to find actual RPM form the specified idle %.

The main thing that worries me is a hung start so keep an eye on the temps and keep the starter engaged.

You will find a lot of tach generators will fit your engine try and get one with 3 pins and gauge with 3 pins as well easiest to hook up.


Cheers

Ian...

[gidge348]

Just had a thought on the mysterious third lever.

Does this engine have adjustable IGV's actuated somewhere?

Or is this some cockpit adjusted IGV, the reason is that the numbers 0-60 may be angles?

Cheers Ian...