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Simple Flying: The Future? This Open Fan Engine Can Cut Flight Emissions By 20%.
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The Future? This Open Fan Engine Can Cut Flight Emissions By 20%
simpleflying.com
Open Fan Engines, the future?
- Thread starter wemay
- Start date
Will be interesting to see if those blades are quieter than props. I've got some definite hearing loss from sitting too close to Brasilia props during my short career at an airline.
Propfans were tried in the 80s by GE, an Allison/Pratt & Whitney joint effort, and Rolls. The problem was never really about efficiency, but noise.
Those aft blades are stators.
Here's one:
And the other major one:
And the other major one:
I worked for an airline that flew all Douglas legacy aircraft, on one trip to Long Beach I saw bits and pieces of that engine including some fan blades. Here's another video of the UDF which was intended to culminate in the MD-94 and associated variants:
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I thought the F18 was going to shoot the DC9 down.
Staggered blades can reduce noise and harmonics as in this Eurocopter tail rotor fan.
Always loved the idea of Un-Ducted fans for modest speed aircraft. They are not ideal for transonic flight, but work well in the M 0.4 to M 0.65 range.
As you might expect, flying slower has some real disadvantages. The ever present headwinds while flying west, or bucking the jet stream is among them. As 120kts on the nose will add a lot of flight time to a 350kt airplane
It’s no surprise that some military transport aircraft use engines and props that mimic propfan performance.
It will be so funny when aircraft go back to what they were before the fuel guzzling jets.
At 90-120 passenger miles per gallon, the modern airliner is hardly a fuel guzzling jet.
I touched on it above, but just like turboprops, open rotor designs cannot efficiently push an airliner to jet speeds. The speeds are much more likely to be no more than 350-400 knots. This means that fuel savings 'per hour' are very much offset by longer flights. Add in a 120 knot headwind and achieving good passenger MPG becomes rather difficult on certain routes, such as westbound travel. (or for that matter, up and down the East coast)
Looking at "seat MPG", there are no turboprops that match the best jets.
If an engine burns half as much fuel, but it takes twice as long to get there, what was saved? Before you dismiss my silly example, remember that maybe it burns 25% less fuel and could possibly take 50% longer with headwinds. And also be subject to typical mid flight level turbulence and icing.
What was the noise in the cabin really like as compared to a jet? As measured in decibels?
You only get exterior views in the surviving test videos of the 80s.
The geared turbofan that PW introduced on the A320 Neo is probably a better option.
You only get exterior views in the surviving test videos of the 80s.
The geared turbofan that PW introduced on the A320 Neo is probably a better option.
I ran across this gem of an article that addresses interior noise. Quite a remarkable piece actually, I never knew about the UHB-270.
"There was the perception an open rotor aircraft suggests interior noise to passengers. McDonnell Douglas claimed that the interior cabin noise levels of the MD-91/92 would be 80dB, which would make it up to 6dB quieter than the jet powered aircraft. McDonnell Douglas claimed that the demonstrator registered 82dB during testing, and that airline executives who flew on marketing flights made statements like “very quiet, better than expected” or “airplane very quiet, particularly in the last row.” This conflicted with reports of other members of the travel industry who said it was very noisy inside, a different type of prop sound, but certainly noticeable and generating some cabin vibration (that would be addressed later on)."
“Props” for McDonnell Douglas: The Unducted Fan Projects That Never Took Off
Airliner technology continues to evolve year-after-year, in the pursuit of better fuel economy which leads to better financial yields for operators. There’s been a number of initiatives over the years…
www.avgeekery.com
Seat MPG took a dive during the big lock downs. Thousands of gallons of fuel to fly a hand full of people around.
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