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Do a quick search on google for "unducted fan" and all will be revealed 
Reportedly such a system could save as much as 40% in terms of fuel burn.
Although this seems much, it was dwarfed by its reversed cousin the "unfanned duct", which saved the other 60%. The UFD is seen here, featured on an experimental Dassault Mercure.
Reportedly such a system could save as much as 40% in terms of fuel burn.
Although this seems much, it was dwarfed by its reversed cousin the "unfanned duct", which saved the other 60%. The UFD is seen here, featured on an experimental Dassault Mercure.
Last edited by A-FLOOR; 30th Oct 2005 at 20:39.
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The photo shows a MD-80 with the UDF on each side. GE also had a 727-100 testbed with only one UDF installed.
'twas designed at a time when fuel costs were in decline from 1980 highs. It showed great promise, but no airline wanted to take on the technical risk of much new technology, with cheaper fuel on the (then) horizon. Cabin noise was also an issue.
Alternative translation of UDF
'twas designed at a time when fuel costs were in decline from 1980 highs. It showed great promise, but no airline wanted to take on the technical risk of much new technology, with cheaper fuel on the (then) horizon. Cabin noise was also an issue.
Alternative translation of UDF
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How did this work
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laugh? Thanks A-Floor
A-Floor you made me laugh, the unfanned duct indeed.
Seriously. Bad idea.
Just as a harp is a nude piano, the UDF is, if not nude, at least a topless jet and is going to have every vice that high speed prop aircraft have and none of the virtues of its lower speed siblings because “ye cannae change the laws of physics”.
Whenever the topic of the UDF arises (and it does every other month) I am reminded of Professor Richard Shevell, of DC-9 and DC-10 fame. When asked where he “saw” the propfan he would reply “On somebody else’s airplane!”
He also used to say that if any of his first year students could not utterly condemn the project in 100 words or less he would see them off to another university.
Dentists and paint sprayers thought it wonderful. My late father who had something to do with it called it the McGonagal Doneless Propbang. He was being kind.
Seriously. Bad idea.
Just as a harp is a nude piano, the UDF is, if not nude, at least a topless jet and is going to have every vice that high speed prop aircraft have and none of the virtues of its lower speed siblings because “ye cannae change the laws of physics”.
Whenever the topic of the UDF arises (and it does every other month) I am reminded of Professor Richard Shevell, of DC-9 and DC-10 fame. When asked where he “saw” the propfan he would reply “On somebody else’s airplane!”
He also used to say that if any of his first year students could not utterly condemn the project in 100 words or less he would see them off to another university.
Dentists and paint sprayers thought it wonderful. My late father who had something to do with it called it the McGonagal Doneless Propbang. He was being kind.
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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?
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?
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toulouse: From an engineering point of view it's always interesting to look at things from the past that didn't work or didn't succeed for reasons other than those purely technical, even if it's just to prevent youreself from trying to reinvent the wheel.
Also, remember that the knowledge gained learning from someone elses mistakes is more often than not more valuable than knowledge gained from someone elses success
Also, remember that the knowledge gained learning from someone elses mistakes is more often than not more valuable than knowledge gained from someone elses success
