3 ms·

Considering that attempts at propfan commercialization has more or less always ended up as a boondoggle for the past ~50 years[1], I'm not especially optimistic

Considering that attempts at propfan commercialization has more or less always ended up as a boondoggle for the past ~50 years[1], I'm not especially optimistic about seeing these engines make it beyond R&D. [1]: https://en.wikipedia.org/wiki/Propfan https://en.wikipedia.org/wiki/Propfan

vidanay 5y ago
Yeah, don't these increase noise by a substantial amount?
- sjm-lbm 5y ago
  https://en.wikipedia.org/wiki/General_Electric_GE36 https://en.wikipedia.org/wiki/General_Electric_GE36 - the Wikipeida article about GE's attempt to commericalize something similar in the late 80s/early 90s seems to infer that there is some options that meet noise requirements while still providing meaningful efficency gains. From the article: "Chapter 4 community noise standards of the International Civil Aviation Organization's (ICAO's) Committee on Aviation Environmental Protection (CAEP), which would go into effect in 2006 and be a reduction of ten effective perceived noise decibels (EPNdB) from the existing Chapter 3 standards that were established in 1977. The regulatory compliance, however, caused a five-percent reduction in fuel efficiency compared to the most efficient fan configuration."
- ghostbrainalpha 5y ago
  They actually have the potential to make less noise. "Some think that propfan engines can potentially cause less of a community impact than turbofan engines, because the rotational speeds of a propfan are lower than that of a turbofan. Geared propfans should have an advantage over ungeared propfans for the same reason."
- dkjaudyeqooe 5y ago
  From the article: "...has only a single fan blade and a variable geometry stator sitting behind it. This layout is expected to be more efficient and significantly quieter."
tzs 5y ago
It looks like several of those attempts failed for reasons that had nothing to do with the aircraft itself. A couple were canceled because they were being developed by the USSR, which broke up during the projects. A third was financed by Ukraine, and got cancelled due to budget shortages there. The Boeing and McDonnell Douglas ones were cancelled because oil became cheap enough that the fuel savings from the planes would not be enough to justify development costs.

vidanay 5y ago

Yeah, don't these increase noise by a substantial amount?

sjm-lbm 5y ago
https://en.wikipedia.org/wiki/General_Electric_GE36 https://en.wikipedia.org/wiki/General_Electric_GE36 - the Wikipeida article about GE's attempt to commericalize something similar in the late 80s/early 90s seems to infer that there is some options that meet noise requirements while still providing meaningful efficency gains. From the article: "Chapter 4 community noise standards of the International Civil Aviation Organization's (ICAO's) Committee on Aviation Environmental Protection (CAEP), which would go into effect in 2006 and be a reduction of ten effective perceived noise decibels (EPNdB) from the existing Chapter 3 standards that were established in 1977. The regulatory compliance, however, caused a five-percent reduction in fuel efficiency compared to the most efficient fan configuration."
ghostbrainalpha 5y ago
They actually have the potential to make less noise. "Some think that propfan engines can potentially cause less of a community impact than turbofan engines, because the rotational speeds of a propfan are lower than that of a turbofan. Geared propfans should have an advantage over ungeared propfans for the same reason."
dkjaudyeqooe 5y ago
From the article: "...has only a single fan blade and a variable geometry stator sitting behind it. This layout is expected to be more efficient and significantly quieter."

tzs 5y ago

It looks like several of those attempts failed for reasons that had nothing to do with the aircraft itself. A couple were canceled because they were being developed by the USSR, which broke up during the projects. A third was financed by Ukraine, and got cancelled due to budget shortages there. The Boeing and McDonnell Douglas ones were cancelled because oil became cheap enough that the fuel savings from the planes would not be enough to justify development costs.