Originally Posted by
Check Airman
I should look that up. I thought all these current generation, oversized engines were geared.
Nope, the PW1100G is one of the few (and by far the largest) turbofan engine to use a geared fan. All the GE and RR Trent engines use a straight shaft to tie the fan to the LP turbine. Those GE and Rolls engines can easily be turned by hand (it takes a bit to get them moving due to the inertia, but once moving you can spin them with one finger). They also routinely slowly spin with a gentle breeze.
Back during the GE90 development, one of the GE engineers showed me an analysis he'd done of how much oil cooling would be required for a gearbox capable of driving the fan on a 100,000 lbs. thrust class engine. Suffice to say the oil cooler would have had to be massive
.