What the heck is going on here?

[Darkwing Duck \(The Duck, The Myth, The Legend\)]

http://www.airliners.net/open.file?id=537804

Anyone know what those fins/blades are all about?

[Paul Tomblin]

In a previous article, "Darkwing Duck \(The Duck, The Myth, The Legend\)" > said:
>http://www.airliners.net/open.file?id=537804
>
>Anyone know what those fins/blades are all about?

Well, the caption on the picture says MD-81 UHB. If you type that into
Google, you find a wealth of information about the UHB or UDF project.
This one will do for a start:
http://www.aerospaceweb.org/question/propulsion/q0067.shtml


--
Paul Tomblin > http://xcski.com/blogs/pt/
Don't even get me started on the MCSEs I know. It's a miracle of
modern technology that some of these fsckwits still draw breath,
much less a paycheck. -- Marc Bowden

[Rob Perkins]

"Darkwing Duck \(The Duck, The Myth, The Legend\)"
> wrote:

>http://www.airliners.net/open.file?id=537804
>
>Anyone know what those fins/blades are all about?
>

For the mechanics who ask too many questions. ;-)

Rob

[Dan Truesdell]

This is GE's UDF (for UnDucted Fan) project. Theory was that the high
efficiency blades would add up to better fuel consumption. The program
was never brought to market. The image you posted is one of the flying
testbeds (possible the only, although I think there might have been a
727 used first).

Darkwing Duck (The Duck, The Myth, The Legend) wrote:
> http://www.airliners.net/open.file?id=537804
>
> Anyone know what those fins/blades are all about?
>
>


--
Remove "2PLANES" to reply.

[John Gaquin]

"Dan Truesdell" > wrote in message

> This is GE's UDF (for UnDucted Fan) project. Theory was that the high
> efficiency blades would add up to better fuel consumption. The program
> was never brought to market. The image you posted is one of the flying
> testbeds (possible the only, although I think there might have been a
> 727 used first).

I never heard about a 727 UDF -- possible, but #2 engine would be a tough
one. I talked to a few folks involved after the project died - I think
around 89 or 90. They said it actually showed a lot of promise, good
efficiency over the jet for short range. But the word was that the
marketing results killed it. It just looked scary. Given a choice, focus
groups always shied away from "prop planes". They were considered old. I
used to run into that in commuter lines, too. People would get off a 20
year old Boeing, and board a brand new t-prop and crack jokes about the
props. A mind is a marvelous thing, wasted.

JG

[Dan Truesdell]

I was at GE's Aircraft Engine Group when this project was going on. I
could be wrong about the 727, but I seem to recall a picture with one of
the outboard engines replaced with the UDF. That was a while ago. It
may have been a mock-up.

I seem to recall that your marketing assessment is correct. I've
spent many hours explaining to fellow travelers (having just stepped
into a Beech 1900) that the plane was, indeed, a jet. Good opportunity
to pass on some knowledge to a public that gets it's aviation from that
oh-so-accurate source: the press.

John Gaquin wrote:
> "Dan Truesdell" > wrote in message
>
>
>>This is GE's UDF (for UnDucted Fan) project. Theory was that the high
>>efficiency blades would add up to better fuel consumption. The program
>>was never brought to market. The image you posted is one of the flying
>>testbeds (possible the only, although I think there might have been a
>>727 used first).
>
>
> I never heard about a 727 UDF -- possible, but #2 engine would be a tough
> one. I talked to a few folks involved after the project died - I think
> around 89 or 90. They said it actually showed a lot of promise, good
> efficiency over the jet for short range. But the word was that the
> marketing results killed it. It just looked scary. Given a choice, focus
> groups always shied away from "prop planes". They were considered old. I
> used to run into that in commuter lines, too. People would get off a 20
> year old Boeing, and board a brand new t-prop and crack jokes about the
> props. A mind is a marvelous thing, wasted.
>
> JG
>
>


--
Remove "2PLANES" to reply.

[DeltaDeltaDelta]

As I dug up from my old Flight Internationals (7-14 January 1989), there
were two UDF engine models:

1.) General Electric GE36 - recognisable by the fact that the jet exhaust
pipes are in the rear of the engine, like in other jets
2.) P&W/Allison 578-DX - their exhaust pipes are just before the unducted
fan and the engine rear (after the fans) is a sealed cone

The major difference was that the fans on the GE36 were directly linked
to the turbine, which was modified to rotated at low speeds, since the
blades were known to produce a lot of noise if they spun quickly. On the
578-DX however, the turbine rotated at normal gas turbine speed, while the
fans were linked with a gearbox that allowed them to rotate at lower speeds.
Also, the fans were counter-rotating. The DC-9 on the airliners.net picture
was used for both engines, though like on the "mysterious" 727 somebody
mentioned, it was installed only on the port side, with the standard JT8D
retained on the starboard. Modifications to the a/c itself were almost
minimal, except for the modification of the port pylon due to the increased
vibrations of the new engine.

Triple Delta

"Dan Truesdell" > wrote in message
...
> I was at GE's Aircraft Engine Group when this project was going on. I
> could be wrong about the 727, but I seem to recall a picture with one of
> the outboard engines replaced with the UDF. That was a while ago. It
> may have been a mock-up.
>
> I seem to recall that your marketing assessment is correct. I've
> spent many hours explaining to fellow travelers (having just stepped
> into a Beech 1900) that the plane was, indeed, a jet. Good opportunity
> to pass on some knowledge to a public that gets it's aviation from that
> oh-so-accurate source: the press.
>
> John Gaquin wrote:
> > "Dan Truesdell" > wrote in message
> >
> >
> >>This is GE's UDF (for UnDucted Fan) project. Theory was that the high
> >>efficiency blades would add up to better fuel consumption. The program
> >>was never brought to market. The image you posted is one of the flying
> >>testbeds (possible the only, although I think there might have been a
> >>727 used first).
> >
> >
> > I never heard about a 727 UDF -- possible, but #2 engine would be a
tough
> > one. I talked to a few folks involved after the project died - I think
> > around 89 or 90. They said it actually showed a lot of promise, good
> > efficiency over the jet for short range. But the word was that the
> > marketing results killed it. It just looked scary. Given a choice,
focus
> > groups always shied away from "prop planes". They were considered old.
I
> > used to run into that in commuter lines, too. People would get off a 20
> > year old Boeing, and board a brand new t-prop and crack jokes about the
> > props. A mind is a marvelous thing, wasted.
> >
> > JG
> >
> >
>
>
> --
> Remove "2PLANES" to reply.
>

[Dean Wilkinson]

The unducted fan engine was being tested on a 727 as part of the 7J7
development. Boeing was considering developing a plane about the size
of the 737 that would use two of these engines, and it was designated
the 7J7. I worked on this program a bit before it was canceled and
replaced by the 7X7 development which became the 777.

Dean Wilkinson

"DeltaDeltaDelta" > wrote in message >...
> As I dug up from my old Flight Internationals (7-14 January 1989), there
> were two UDF engine models:
>
> 1.) General Electric GE36 - recognisable by the fact that the jet exhaust
> pipes are in the rear of the engine, like in other jets
> 2.) P&W/Allison 578-DX - their exhaust pipes are just before the unducted
> fan and the engine rear (after the fans) is a sealed cone
>
> The major difference was that the fans on the GE36 were directly linked
> to the turbine, which was modified to rotated at low speeds, since the
> blades were known to produce a lot of noise if they spun quickly. On the
> 578-DX however, the turbine rotated at normal gas turbine speed, while the
> fans were linked with a gearbox that allowed them to rotate at lower speeds.
> Also, the fans were counter-rotating. The DC-9 on the airliners.net picture
> was used for both engines, though like on the "mysterious" 727 somebody
> mentioned, it was installed only on the port side, with the standard JT8D
> retained on the starboard. Modifications to the a/c itself were almost
> minimal, except for the modification of the port pylon due to the increased
> vibrations of the new engine.
>
> Triple Delta
>
> "Dan Truesdell" > wrote in message
> ...
> > I was at GE's Aircraft Engine Group when this project was going on. I
> > could be wrong about the 727, but I seem to recall a picture with one of
> > the outboard engines replaced with the UDF. That was a while ago. It
> > may have been a mock-up.
> >
> > I seem to recall that your marketing assessment is correct. I've
> > spent many hours explaining to fellow travelers (having just stepped
> > into a Beech 1900) that the plane was, indeed, a jet. Good opportunity
> > to pass on some knowledge to a public that gets it's aviation from that
> > oh-so-accurate source: the press.
> >
> > John Gaquin wrote:
> > > "Dan Truesdell" > wrote in message
> > >
> > >
> > >>This is GE's UDF (for UnDucted Fan) project. Theory was that the high
> > >>efficiency blades would add up to better fuel consumption. The program
> > >>was never brought to market. The image you posted is one of the flying
> > >>testbeds (possible the only, although I think there might have been a
> > >>727 used first).
> > >
> > >
> > > I never heard about a 727 UDF -- possible, but #2 engine would be a
> tough
> > > one. I talked to a few folks involved after the project died - I think
> > > around 89 or 90. They said it actually showed a lot of promise, good
> > > efficiency over the jet for short range. But the word was that the
> > > marketing results killed it. It just looked scary. Given a choice,
> focus
> > > groups always shied away from "prop planes". They were considered old.
> I
> > > used to run into that in commuter lines, too. People would get off a 20
> > > year old Boeing, and board a brand new t-prop and crack jokes about the
> > > props. A mind is a marvelous thing, wasted.
> > >
> > > JG
> > >
> > >
> >
> >
> > --
> > Remove "2PLANES" to reply.
> >

[JohnMcGrew]

In article >, "Darkwing Duck \(The Duck, The
Myth, The Legend\)" > writes:

>Anyone know what those fins/blades are all about?

It was another one of those projects that looked good on paper, but in the end,
was more cost and trouble than it was worth. There wasn't enough of an
increase in efficiency to make the effort worthwhile, while at the same time
there were noise and vibration issues that would have been expensive to
resolve.

I do remember watching it land at LGB while I was at school there. It made a
rather distinctive sound.

I know that at least one of those engines is in the Smithsonian now.

John