Propfan Engines

[kernals12]

This odd contraption is a propfan engine. It's sort of like a Turboprop but with slender blades that allow for efficient high speeds. In the 1980s it was the wave of the future, claimed to be able to cut fuel use by 30%. But it never caught on because of the problem of noise which never was fixed. But why couldn't they be used in military applications? Surely noise is much less of an issue in that field.

 

[e of pi]

I'd say the two major reasons are the military (1) tends to not care about fuel efficiency as much, particularly for the cargo aircraft and such that tend to use high bypass turbofans and (2) the unducted fan only came out about 30 years ago and a lot of those types of aircraft haven't had many major new programs since then. The C-17 made its first flight in 1991, only a few years after the first test of propfans on test stands. As a sort of halfbred derivative of a turboprop and a conventional turbofan with the same fan blade technologies, the propfan got beaten to applications by one or the other for most niches.

 

[kernals12]

I'd say the two major reasons are the military (1) tends to not care about fuel efficiency as much, particularly for the cargo aircraft and such that tend to use high bypass turbofans and (2) the unducted fan only came out about 30 years ago and a lot of those types of aircraft haven't had many major new programs since then. The C-17 made its first flight in 1991, only a few years after the first test of propfans on test stands. As a sort of halfbred derivative of a turboprop and a conventional turbofan with the same fan blade technologies, the propfan got beaten to applications by one or the other for most niches.

Fuel supplies are a major chokepoint for the military, I think they'd care about fuel efficiency.

 

[Dathi THorfinnsson]

Fuel supplies are a major chokepoint for the military, I think they'd care about fuel efficiency.

You'd think so, wouldn't you. But B-52 s are still using their original engines despite half a century if technology advances.

 

[kernals12]

You'd think so, wouldn't you. But B-52 s are still using their original engines despite half a century if technology advances.

No they aren't, the early ones used turbojets. They now use turbofans and the air force wants to replace those

 

[lhagambia]

No they aren't, the early ones used turbojets. They now use turbofans and the air force wants to replace those

The most recent model, the B-52H, entered service in 1961 and still uses the TF33 engines it entered service with.