Joined: 3:53 PM - Mar 01, 2005

1:56 AM - May 05, 2018 #171

Naval gas turbines have always been a "major repair by replacement" item at the ship level, with only minor repairs being conducted with the GT installed in the ship.

This has always required a number of "spares" to be in inventory to provide those replacements, and to cover extended maintenance times if parts are slow to arrive or the repair is more-involved than originally assessed to be.

All that comment means is that Defender's GTs were replaced with ones from the "spares" stock, probably by ones with "fixes" applied.


An example of the procedure:
http://www.navy-marine.forces.gc.ca/en/ ... f/hr0e3ova

The first pic is of HMCS Toronto's General Electric LM2500 that was replaced in-port in the Persian Gulf at the end of 2013.
 The second is one of the Speys of HMS Westminster being removed in late 2012.
HMCS Toronto gas turbine replacement in the persian gulf Dec 2013.jpg
changing the Spey on a T23.jpg
There it is... the District of Columbia! You will never find a more wretched hive of scum and villainy. We must be cautious.
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Joined: 8:08 PM - Jun 22, 2008

2:42 PM - May 05, 2018 #172

Cheers bager, that all makes sense.  The issue I have though is that I'm pretty sure I read somewhere that the RN only ever acquired 12 WR21s.  Does sound a bit counter-intuitive so maybe it's simply not the case.
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Joined: 9:17 PM - Jul 16, 2015

3:31 PM - May 05, 2018 #173

Bager doesn't know any more than you about Defender's GT's. He's just speculating.
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Joined: 4:39 AM - Oct 07, 2009

10:39 PM - May 05, 2018 #174

While he may be speculating about what was actually done on this case, he is correct about the way in which GT engines are managed.

I don’t know how many engines the RN bought, or what the details of the support contracts may be, but if you are going to use GTs you must have access to spares as they will, at some point, break unexpectedly due to FOD or some other cause, never mind the need for routine oprating hour based replacement and, having been using them for more than 50 years, the RN knows this well.
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Joined: 8:22 PM - Mar 16, 2017

7:11 PM - May 16, 2018 #175

Has anyone put out a definitive list of the changes in the Defender refit?
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Joined: 2:26 PM - Feb 12, 2018

6:31 PM - Jun 17, 2018 #176

BBMW wrote: Has anyone put out a definitive list of the changes in the Defender refit?
She was fitted with two new gas turbines in her refit and has been updated with this Shaman CESM fit as well.
http://www.janes.com/article/80634/firs ... n-cesm-fit
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Joined: 12:37 PM - Nov 04, 2017

7:20 PM - Jun 17, 2018 #177

Seawall wrote:She was fitted with two new gas turbines in her refit and has been updated with this Shaman CESM fit as well.
http://www.janes.com/article/80634/firs ... n-cesm-fit
That news story is incorrect. Defender was installed with the newly designed intercooler-recuperators which are components of the GTs. The T45s will receive diesel replacements in the 2020s. 
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Joined: 7:37 PM - May 28, 2013

6:22 PM - Jun 18, 2018 #178

So no new GT's, maybe an improvement in output power?
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Joined: 8:12 PM - Apr 04, 2012

7:03 PM - Jul 09, 2018 #179

The Project Napier Propulsion Improvement Programme (in big handfuls) is basically the replacement of the very fragile Ingersoll Rand designed and built GT Recuperators and the installation of a third 4MW diesel generator. Rolls Royce have been busy designing ther own version of this and it is far more robust and useable than the old one. Strangely enough, the original recuperator wasn't included in the support contract undertaken by BAE (RNs fault) and any subsequent defects were both costly to price and availability for Rolls and BAE to fix. An interim blanking solution was dreamed up which was a git to fit and reduced output and efficiency.  Better operating procedures and appreciation of the old recuperator's capabilities has reduced recuperator losses whilst the new units are fitted on refit.

Note - one should not use the terms 'recuperator' and 'intercooler' in the same sense. The recupertor sits in the exhaust collector and gains heat from the exhaust into the cycle before combustion, whereas the 'intercooler' sits between the Intermediate and High Pressure Compressors and effectively gains efficiency by increasing the volumetric flow of compression air. Used together, they make the WR21 a very efficient engine and the design, although proven to be problematic, is basically sound.

The addition of the extra diesel generator adds flexibility to the HV generative capacity of the ship. Once PIP is installed, we should see the T45 a far better warship.

ship fixer
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Joined: 9:17 PM - Jul 16, 2015

7:40 PM - Jul 09, 2018 #180

Thanks very much ship fixer.
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