Happy-flier
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The JT3D Is Just A JT3C With A Fan - Is This True?

Tue Mar 23, 2004 6:24 am

I read sometime back that the JT3D series of engines is basically a JT3C turbojet at the core, with an additional fan stage compressor added on. Is this true? Is that the only difference between the JT3C & the JT3D?

Many thanks.
May the wind be always at your back . . . except during takeoff & landing.
 
QantasA332
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Tue Mar 23, 2004 6:31 am

I found the following from here...ah, the wonders of Google.

"Based upon the JT3C turbojet, P&W's first production turbofan—the JT3D—had a two-spool compressor. It became a turbofan by changing the two front stages on the front compressor and adding an additional turbine stage (needed to drive the much larger new front spool). So clever was the derivative that Pratt & Whitney offered a kit to convert the JT3C turbojets to turbofans. Several airlines took up the company on its offer."

I hope that helps,
QantasA332
 
Happy-flier
Topic Author
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Tue Mar 23, 2004 6:41 am

Awesome! Thanks a lot.

I never thought Google would have anything on that ...  Laugh out loud
May the wind be always at your back . . . except during takeoff & landing.
 
gigneil
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Tue Mar 23, 2004 7:24 am

Google has everything on everything.

Aviation related: aviation is part of everything.

N
 
broke
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Wed Mar 24, 2004 12:03 am

An story on how P&WA got into building turbofan engines
A P&WA executive went to a technical conference in which Rolls-Royce made a presentation on the Conway, which was the first turbofan or by-pass engine.
When the P&WA representative was queried on what the company was doing, he told them that they had planned on having a turbofan engine running in a test stand shortly and everyone would be invited to come see.
On his return the East Hartford, he asked what the h_ll a by-pass engine was?
P&WA took a JT3C engine and replaced the first two stages with the first two stages from a JT4A which had a larger diameter. The cases were cobbled up to produce the by-pass and still provide structural support.
When this engine went to test, the thrust and fuel consumption figures demonstrated that there was a lot of promise even though this was not an optimum match.
From this the JT3D engine was developed.
The JT8D has a similar history.
The JT8A engine was developed for the Hound Dog Air to Surface missile as a turbojet throw away engine.
From this came the JT8B, which is the military J-52 used on later Douglas A-4's and Grumman A-6's.
When Boeing came knocking looking for an engine for the 727, P&WA did studies on a turbofan JT8 and the JT8D was born.
 
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Starlionblue
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Wed Mar 24, 2004 12:57 am

LOL. That salesman reminds me of some of the salesmen I've worked with.

I'll amend that: He reminds me of ALL the salesmen I've worked with.  Smile
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Guest

RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Wed Mar 24, 2004 1:08 am

Dear Happy-flyer -
xxx
Like they all said... yes, JT3C, put a fan, you get a JT3D...
By the way the JT3C, was originally known as the military J-57...
Then the JT3D, got a military name: TF-33... etc. etc...
xxx
Not the only engine that got a "fan" as an afterthought...
How about the CJ805... cannot remember dash number - straight pipe on the CV-880...
It became an "aft fan" engine for the CV-990, known as the CJ805-23.
And the original military name of the CJ805 was the J-79 (of F-104 and F-4 fame)
xxx
Another example - The CJ610 (Learjet 23) was originally the J-85...
Then it got an "aft fan" as well, known as the CF700... on the Falcon 20...
xxx
Happy contrails  Smile
(s) Skipper
 
Happy-flier
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Wed Mar 24, 2004 1:28 am

Thanks Skipper. I have always thought the CV-990 aft-fan engines to be interesting, but they sure look a heck of a lot more vulnerable in the event of a bird strike! A fan in the front would at least chop the bird up before it entered the turbojet core ... I can just imagine a bird getting sucked into the central "pipe" of a CJ805-23 and shutting it down!  Wow!

By the way, did that even happen in reality to a CJ805-23?

Cheers.
May the wind be always at your back . . . except during takeoff & landing.
 
Guest

RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Wed Mar 24, 2004 1:46 am

No experience with the CJ805-23... cannot tell you.
xxx
But what I can tell you, any bird of size into any engine spells disaster for the engine. As soon as these compressor blades are bended (or broken) by a bird, this impedes (or even stops) shaft rotation, immediate result, the turbine gets cooked, and here goes the engine.
xxx
Most of the fans are "front fan" designs, the "aft fan" concept, only GE designed engines like that. At least to my knowledge. I do not know if there is much difference in incidence of bird strikes of front fans vs. aft fans... The airplanes with aft fan (CV-990, DA-20, DA-50) are much of "ducted nacelles" design.
xxx
So the way the little birds get roasted... beats me.
A few birds destroyed perfectly good "motors" of mine...
I hate chicken ever since. Here in Argentina, we eat beef anyway...!
xxx
Happy contrails  Big grin
(s) Skipper
 
BR715-A1-30
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Mon Mar 29, 2004 12:14 am

I wonder what a JT9A would look like. A JT9D but without the huge fan, or better yet, a PW4000 112 incher without the fan.
Puhdiddle
 
747400sp
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RE: The JT3D Is Just A JT3C With A Fan - Is This True?

Sun Feb 11, 2007 12:46 pm

Quoting BR715-A1-30 (Reply 9):
I wonder what a JT9A would look like. A JT9D but without the huge fan, or better yet, a PW4000 112 incher without the fan.

Lets not talk what it will look like, lets talk about how it would sound. I have a felling it would be very loud !

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