3 ms·

It'd be interesting to know what exactly they are doing in the gearbox, apart from the flexible mount to absorb excess torque. New materials? Surface treatments

• rm445 11y ago
  This article has much more detail: http://theflyingengineer.com/flightdeck/pw1100g-gtf/ http://theflyingengineer.com/flightdeck/pw1100g-gtf/ The gearbox is described as the epicyclic type with the compressor driving the sun gear and the carrier of the five planet gears driving the fan. The article doesn't seem to identify any extra special sauce. It points out that geared turbofans have been used on an airliner in the past, and identifies some design trade-offs. "there may be a performance penalty, marked by slower cruise speeds for the same thrust setting, possibly slower max cruise speeds, slower green dot (best L/D speed), slightly shallower climbs, and possibly degraded single-engine performance. The single engine performance difference is expected to be the most prominent, with a possibly larger yaw, and a definitely reduced climb gradient, consequently lowering obstacle clearances." My impression based on just reading that article is that, rather than a technological breakthrough enabling the geared approach, Pratt and Whitney have explored a rather neglected area of the design space, to arrive at a more efficient, lower noise engine with slightly worse performance in some other respects. And had to conquer numerous 'ordinary' engineering challenges to make it work.
  • dognotdog 11y ago
    Thanks, that article was indeed much better to understand what's going on. Still, as mentioned, high-speed gearing of the kind does offer some design challenges, but apparently its all secret sauce.