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Engine model numbers

Old 29th Jun 2007, 09:43
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Engine model numbers

Just wondering what the post nominals mean for turbine engine model numbers. eg. the GE90-115B .... I think the 115 denotes 115,000lb thrust, but what about the "B"?

What about thr PW-4000-94 (or... -100, -112)? And how is it different to the PW-4168A... how does it differ from the PW-4000??

Regards,
Confused
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Old 29th Jun 2007, 11:52
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hi over

It also applys to jet engines as well , the 330's I fly have - 202 / 234 the former being the no for GE engines and the latter for rolls royce ...... there are also changes in engine power settings , derates , trust bumps and so on between the two , also the GE's give N1 Displays on the EWD up on deck however the rolls gives EPR readings ... just to name a few differences .....

comes in handy also when one is studying the limitations of both

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Old 29th Jun 2007, 15:02
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Engine model numbers are as much defined by marketing as by engineers.

In other words if it's different in any way capitalize on the difference with a name change. However if a model is selling well and a completely new name would sound different, then it is not a good idea, so just add a small change like a -1 or a "b" after the model.

The general public (non buyer) would never be expected to sort this out logically.

I believe that this applies to auto engines as well
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Old 29th Jun 2007, 20:40
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They are really arbitrary designations. There is a CF6-50C2B, which is a standard-day "bump" of the flat-rated CF6-50C2. I think Finnair bought it for a few long-leg DC-10-30's.

One oldie always puzzled me: the R-985-AN14B, which had an extra oil passage for the 22D30 full-feathering prop. There never was an R-985-AN14 (sans B) as far as I know.
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Old 30th Jun 2007, 02:02
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Some of the missing variations in model numbers only appear to be missing in the market place. In actuality they were assigned in a development phase but the program was later canceled. Since there is always hope that it may someday come back to life the missing numbers are not reassigned for years or if ever.

Then there is the mix of military projects morphing into commercial projects and tacking on a designator change like the J52/JT8 into the JT8D and since that was such a good seller when an almost completely new engine was designed using only parts of it's HPC they decided to just stretch out the new name and call it a JT8DR, but that didn't sound right to marketing so they called it a JT8D-200.

There was the JTF10 project that died but morphed into a PW2037 used on the B757. It's really interesting to think back about the reasoning for some of these names, but like I said before it's part engineering changes and part marketing recognition (good or bad)
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Old 30th Jun 2007, 11:26
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The PW engines in the 400 series seem to break down into three families. PW4000 for Boeings/Airbus A300/310 and PW4100 for the A330. A PW4060 will therefore be a 60,000lb model and a PW4168 a 68,000 model for the A330 with a larger fan.

Pratt conflustered it when they put the larger PW4000 variants in with the earlier numbering, so the PW4098 is in there despite being a much wider fan and higher thrust variant than the earlier engines.

Nowadays a lot of the designations refer more to software or electronics changes rather than physical differences. For instance a GE90-110B1 is a derated GE90-115 despite being physically the same engine, and something similar applies to changing the RB211 from a G to a H version.
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Old 2nd Jul 2007, 14:07
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at www.faa.gov you click on Tab -> Licenses & Certificates
go to Aircraft subsection "Type Certificates " and subsubsection "Type Certificate Data Sheets (TCDS) "
now on the left side type PW4* in the Search Field.
You get a list of all PW4... Engine TCDS (Type Certificate Data Sheet)

Compare and have fun...
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Old 2nd Jul 2007, 14:18
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Engine model numbers of jet engines are allocated by each manufacturer to their own style.

In contrast piston engines have an industrywide standard across all manufacturers. There are prefix letters which describe the engine layout, and a number suffix which gives the size in cubic inches.

Thus the Pratt & Whitney large engine that went in the Stratocruiser was an R-4360, R for Radial and 4360 for the total cubic inch displacement. If Wright or Lycoming or anyone else had built an equivalent engine it would have had the same designation.

It doesn't tell you anything about developments in the engine or its power (though 1 cu in = 1 hp is a very, very broad approximation).
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Old 2nd Jul 2007, 16:54
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The Stratocruiser engine (per FAA type certificate E-247) was the P&W Wasp Major. The military equivalent was the R-4360, and it was the US military that imposed the uniform R-, O-, V- etc. numbering system. The number assigned is the CID rounded off to the nearest 5.

And yes, two completely different engines could wind up with the same designation. There was a Curtiss V-1650 of 600 HP in the 30s, and the famous Rolls V-1650 of double that HP (built by Packard in the US) in WWII.
(I once helped assemble the former for a museum aircraft.)
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