we have moved on
Gentlemen
When engines consumed 1 lb of fuel per hour per lb of thrust then a 40% reduction would bring this down to 0.6lb which we have today, have we not and better?
Ah yes! Blade containment? I suggest we enclose a very large fan or even tandem fans in a housing. How big? Well yes I would put them on the wing not the tail and so the critical size is determined by having no damage to the engine should the nosewheel collapse. Maybe 9-10 times the amount of air can pass through the ducted fans than the core.
Fuel efficiency? Well instead of dwelling in the past read NASA NOW about the Ultra Efficient Engine Technology Program. But meanwhile, my idea, I think perhaps we will not call it the ducted fan. I like the name turbofan. I shall patent it. Oh yes you keep asking about fuel efficiency. Very well. Does 0.53 lb per lb hour suit you? and no no no. Taking the covers off does not reward you with an immediate 40% improvement.
She is very quiet and vibration free this new-fangled idea of mine. Residents near aeroports are very happy. Bean counters delighted. Engineers in fits of delirium. Passengers choose it
My friends all of you the unducted fan is dead, why have you a fascination?