CFMI: The Next 35 Years

I’m sitting in Terminal 1 at O’Hare on stand-by, taking the scenic route back to DC from Cincinnati.

I’ve recently changed reporting jobs, moving from an all-defense beat at Jane’s to an all-aerospace beat at Flight. Happily, this means I have license to pay a visit to the headquarters of CFM International just north of Cincinnati.   

As the well-maintained joint venture between General Electric and France’s Snecma, CFMI is the brainchild behind the world’s highest-selling engine: the CFM56 family that currently powers the two (not coincindentally) highest-selling commercial airliner designs in history: the entire Airbus A320/319/321 line-up and all members of the Boeing 737 family after the -200. Throw in the CFM56-5C that powers the Airbus A340.

As with most commercial aviation innovations, the CFM56 owes its existence to the military on two counts. First, GE’s work on the F101 engine for the Rockwell B-1A bomber produced the high-pressure core that merged with the Snecma-built fan and low-pressure section. Later, it was the US Air Force that kept the program alive by agreeing to re-engine a portion of the KC-135 fleet (hence the KC-135R).

It’s an interesting time to pay CFMI a visit. The joint venture is plotting how to build a new engine that power the (still undetermined) aircraft types that will eventually replace the 737 and A320, as both are presumed by industry to become out-of-date at some point within the next decade.

CFMI’s answser is bold and highly interesting: an all-new engine core driving two sets of counter-rotating blades. Instead of the usual ducted fan, the 12-14-foot diameter blades spin out in the open. Compared to the single-digit air bypass ratios of most conventional ducted fans, the CFMI’s "open rotor" concept offers bypass ratios on the order of 35:1.

This is the concept that CFMI hopes to literally propel the single-aisle airline industry from 2020 until — presumably, if the 1980-2020 lifespan of the 737 is any indication — 2060 or beyond.

Now, there are quite a few "if’s" that come up. The new engine core has to be developed to make the open rotor configuration possible. The extra noise generated by the free-spinning blades will have to be mitigated in some way or accepted despite the worldwide clampdown on aircraft noise emissions. And, not least, airlines will have to sell consumers on the idea of flying on a jet that looks an awful lot like a turboprop.

Another interesting sub-plot is watching the relationship between GE and Snecma evolve with an all-new engine program. Legend has it that the CFM56 was only days away from cancellation when the first order came through to re-engine United DC-8s. Among joint ventures, the CFMI pairing is unusally strong — see this article (warning: subcription required) in this week’s The Economist, which hails CFMI as perhaps the world’s most sucessful joint venture in history.  The agonies of developing a sophisticated and original new engine will surely put even CFMI’s winning formula to the test.


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5 Responses to CFMI: The Next 35 Years

  1. LowObservable 8 May, 2007 at 9:24 am #

    A counter-rotating high-speed prop? You might call it an UnDucted Fan or Prop-Fan. And the near-cancellation story is pretty much the literal truth. United had to take the CFM56, rather than the JT8D-200, for its DC-8-61s to make sense of a program that also included Flying Tiger’s 63Fs. Without that, there was no CFM56 application in sight for years.

  2. Stephen 8 May, 2007 at 9:47 am #

    Mr. LowObservable,

    The GE36 engine prototype tested — and dumped — in the late-1980s was called the UnDucted Fan, or UDF. But CFMI is very careful to call this new concept the Open Rotor, probably to avoid the association with the previous program that failed to spark any commercial interest.

  3. LowObservable 8 May, 2007 at 1:31 pm #

    But what happened just before the UDF was dumped? Keywords: Saudi, spigot, Reagan.

  4. Stephen 8 May, 2007 at 1:45 pm #

    I think I understand your point. The price of oil fell and the market demand for the super-efficient — if unsightly — UDF plunged along with it.

  5. Alex 9 May, 2007 at 5:36 am #

    Ah-ha. I was wondering how long it would take for someone to dust off the UDF concept and cash the 30 per cent fuel saving.

    I wonder how Rolls-Royce will respond.

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