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Coomb t1_j5ielgn wrote

Reply to comment by slowslownotbad in Seattle-based Jetoptera is developing a vertical takeoff aircraft that can travel at almost 1,000 km/h with a radically simplified new type of engine. With almost no moving parts, it uses super-compressed air to create vortexes for thrust. by lughnasadh

Conventional turbofan engines don't have a gearbox or transmission. The closest thing they get is that they might have two or at most three shafts for their turbine/compressor stages.

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slowslownotbad t1_j5ifpmo wrote

That's true. The main advantage of this over a turbofan is size - efficient turbofans are quite large.

To be fair, small turbofans do exist, but they're not very efficient. For instance, a cruise missile engine might do 0.683 lb/lbf/h (https://en.wikipedia.org/wiki/Williams_F107).

Whereas Jetoptera claims as low as 0.26 lb/lbf/h (https://jetoptera.com/products/). FYI smaller is better, so Jetoptera is claiming better than 2x efficiency when compared to a small turbofan.

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im_thatoneguy t1_j5kr3rt wrote

>That's true. The main advantage of this over a turbofan is size - efficient turbofans are quite large.

The main advantage of this over a turbofan is that it can be rotated to offer VTOL or STOVL options.

Pretty easy to rotate a relatively low velocity duct vs rotating an entire turbofan or creating a complex orbital gear to deliver the turbine power to the fans. (See: complicated clutch issues with the F35 VTOL.)

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