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747400sp
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Why The Usaf Cancel The YC-14 & YC-15

Tue Feb 21, 2006 8:19 am

In the mid 70's the USAF was looking for a jet replacement for the C-130. Both Boeing and Mcdonnell Douglas flew their prototype, Boeing had the YC-14 and Mcdonnell Douglas YC-15. The YC-14 and YC-15 out performed the USAF expectation. So why the USAF drop the project.


PS I thought the YC-15 was the best choice
 
474218
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RE: Why The Usaf Cancel The YC-14 & YC-15

Tue Feb 21, 2006 9:52 am

Because the C-130 could do everything the YC-14 and YC-15 clould do, and do it for a lot less money.
 
Dougloid
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RE: Why The Usaf Cancel The YC-14 & YC-15

Tue Feb 21, 2006 9:58 am

Good point. The money wasn't totally wasted though, a lot of the YC15 development work went into the C17
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N328KF
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RE: Why The Usaf Cancel The YC-14 & YC-15

Tue Feb 21, 2006 10:36 am

Quoting Dougloid (Reply 2):
Good point. The money wasn't totally wasted though, a lot of the YC15 development work went into the C17

A lot? The C-17 looks like a super-sized, swept-wing YC-15.  Wink
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scbriml
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RE: Why The Usaf Cancel The YC-14 & YC-15

Thu Feb 23, 2006 4:01 am

The YC-15 looked cool, but those engines didn't look like they could get it off the ground.

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Dougloid
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RE: Why The Usaf Cancel The YC-14 & YC-15

Thu Feb 23, 2006 10:39 am

Quoting N328KF (Reply 3):
Quoting Dougloid (Reply 2):
Good point. The money wasn't totally wasted though, a lot of the YC15 development work went into the C17

A lot? The C-17 looks like a super-sized, swept-wing YC-15.

And even before the C17 got built we were all proud that the YC15 whupped the Boeing offering.  bigthumbsup   bigthumbsup 
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whitehatter
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RE: Why The Usaf Cancel The YC-14 & YC-15

Fri Feb 24, 2006 9:14 am

Quoting Scbriml (Reply 4):
The YC-15 looked cool, but those engines didn't look like they could get it off the ground.

Deceptive photos.

The YC-15 used the JT8D, so it had the power of two 732 or DC-9 aircraft after all.

Boeing's offering used a pair of CF6 engines.
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RE: Why The Usaf Cancel The YC-14 & YC-15

Tue Feb 28, 2006 12:57 pm

The Boeing YC-14 was technologily musch more advanced. The 2 CF-6 engines were mounted on the wing leading edge, thrust was blown over both the upper and lower wing surface, producing an enormaos amount of lift. The YC-14 clearly out performed the 4 engine MD YC-15. It could lift a lot more weight than either the C-130 or YC-15.

But, later in life, the YC-15 test airplane was used to flight test the (then newly designed) CFM-56-B2 engine.
 
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RE: Why The Usaf Cancel The YC-14 & YC-15

Tue Feb 28, 2006 11:52 pm

Quoting KC135TopBoom (Reply 7):
The Boeing YC-14 was technologily musch more advanced. The 2 CF-6 engines were mounted on the wing leading edge, thrust was blown over both the upper and lower wing surface, producing an enormaos amount of lift. The YC-14 clearly out performed the 4 engine MD YC-15. It could lift a lot more weight than either the C-130 or YC-15.

Yes, and then the Soviets wound up using the Coanda effect for the An-72 design.
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RE: Why The Usaf Cancel The YC-14 & YC-15

Thu Mar 02, 2006 6:41 am

Quoting 474218 (Reply 1):
Because the C-130 could do everything the YC-14 and YC-15 clould do, and do it for a lot less money.

That and the fact the USAF realized they truly needed a bigger plane than the YC-14/YC-15, so as not to repeat the experience with the C-141 Starlifter. The result is the C-17A Globemaster III.
 
zwaving
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sat Jul 21, 2007 9:15 pm

What was the experience factor with the starlifter?
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Stealthz
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sat Jul 21, 2007 9:31 pm

Quoting Zwaving (Reply 10):
What was the experience factor with the starlifter?

IIRC, it was too small for it's weight carrying capacity.
If that doesn't seem to make sense, it often filled the available volume before reaching max weight. This led to the C-141B which were C-141A with plugs inserted in the fuselage fore and aft of the wings adding a total of 23ft 4in to the length.

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dl021
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sat Jul 21, 2007 9:37 pm

Quoting StealthZ (Reply 11):
IIRC, it was too small for it's weight carrying capacity.
If that doesn't seem to make sense, it often filled the available volume before reaching max weight. This led to the C-141B which were C-141A with plugs inserted in the fuselage fore and aft of the wings adding a total of 23ft 4in to the length.

I think that it's a very rare thing to max out a freighter weight wise prior to filling the volume. What they really wanted was a wider airplane to make more stuff fit inside.
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kc135topboom
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sat Jul 21, 2007 9:50 pm

The C-141B mod also added air refueling capability that the C-141A did not have.
 
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sat Jul 21, 2007 9:57 pm

Quoting DL021 (Reply 12):
I think that it's a very rare thing to max out a freighter weight wise prior to filling the volume.

Not rare at all, much cargo is not that dense.
Much military cargo comprises things like helicopters, wheeled vehicles etc these will max out volume long before weight is an issue.

Quoting DL021 (Reply 12):
What they really wanted was a wider airplane to make more stuff fit inside.

Absolutely agree, but what you want you can't always have.. had to wait for the C-17 to get the width.
Adding width to the C-141 was not an option so a stretch was the compromise they had to live with.

Quoting KC135TopBoom (Reply 13):
The C-141B mod also added air refueling capability that the C-141A did not have.

Sorry KC135... should have mentioned that!


Cheers

[Edited 2007-07-21 15:00:19]
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 3:41 am

Quoting 474218 (Reply 1):
Because the C-130 could do everything the YC-14 and YC-15 clould do, and do it for a lot less money.

......and 30 years later it is still doing it.
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CTR
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 4:07 am

Neither the YC-14 or YC-15 programs were canceled. To be canceled you first need to be awarded a contract to develop a production aircraft.

Both the YC-14 and YC-15 were technology development prototype aircraft built to test advanced heavy lift concepts. The size of these aircrafts was based on the minimum size (least $$$) required to be scaleable to larger aircraft, not as a C-130 replacement.

Each aircraft had their own merits. Although the lift performance of the YC-14 was impressive, the associated complexity in the engine, wing and moving surfaces was judged by the USAF as unacceptable.

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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 4:25 am

Quoting KC135TopBoom (Reply 13):
The C-141B mod also added air refueling capability

To chime in a 4th time, it also had major wing root mods, IIRC, didn't it have problems with cracks?
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L-188
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 4:52 am

Quoting Zwaving (Reply 10):
What was the experience factor with the starlifter?



Quoting StealthZ (Reply 11):
If that doesn't seem to make sense, it often filled the available volume before reaching max weight. This led to the C-141B which were C-141A with plugs inserted in the fuselage fore and aft of the wings adding a total of 23ft 4in to the length.

A little history here, the C-141 was built to replace the C-133. Both of which had one mission in life when they where developed. To carry a minuteman missle in it's shipping container. That is why they where able to keep the C-130 sized floor dimensions.

But as noted it was quickly realized that a lot of their capacity was wasted when they wheren't carrying a heavy ICBM and it's shippng cradle so that is why they decided to stretch the aircraft and take advantage of the whole lift capability of the aircraft.

Quoting CTR (Reply 16):
Both the YC-14 and YC-15 were technology development prototype aircraft built to test advanced heavy lift concepts. The size of these aircrafts was based on the minimum size (least $$$) required to be scaleable to larger aircraft, not as a C-130 replacement.

That was my understanding, it was a test program not a program leading to a production run.
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Thorny
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 6:08 am

Quoting AirSpare (Reply 17):
To chime in a 4th time, it also had major wing root mods, IIRC, didn't it have problems with cracks?

No, that was the C-5A.
 
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 7:29 am

Quoting Thorny (Reply 19):
C-5A.

I thought there was a cracking problem. Here is a good synopsis. I had remembered it as part of the upgrade to the B models but it wasn't.
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TropicBird
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RE: Why The Usaf Cancel The YC-14 & YC-15

Sun Jul 22, 2007 11:02 am

As I recall the YC-15 was the precursor to the C-17... MDC won the competition over Boeing.
 
MCIGuy
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RE: Why The Usaf Cancel The YC-14 & YC-15

Mon Jul 23, 2007 2:37 pm

Quoting TropicBird (Reply 21):
As I recall the YC-15 was the precursor to the C-17... MDC won the competition over Boeing.

I was gonna say, put some HBT engines on that YC-15 and you have the look of the C-17, even if the 17 is larger.  

PS> I had the pleasure of seeing the YC-14 at Pima. There's just something about touching one of only two aircraft.  

[Edited 2007-07-23 07:44:56]
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DeltaGuy
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RE: Why The Usaf Cancel The YC-14 & YC-15

Mon Jul 23, 2007 9:46 pm

Quoting StealthZ (Reply 11):
If that doesn't seem to make sense, it often filled the available volume before reaching max weight. This led to the C-141B which were C-141A with plugs inserted in the fuselage fore and aft of the wings adding a total of 23ft 4in to the length.

That was the problem, being just a stretched C-130 really. It was that...then the C-5. No middle ground like the C-17 is now.

I did like the old 141 though....miss those old Lockheeds.

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RE: Why The Usaf Cancel The YC-14 & YC-15

Wed Jul 25, 2007 1:19 am

Quoting AirSpare (Reply 17):
To chime in a 4th time, it also had major wing root mods, IIRC

The first aircraft modified got the wing root mods, but they weren't incorporated on subsequent aircraft, to save money.
 
Thorny
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RE: Why The Usaf Cancel The YC-14 & YC-15

Wed Jul 25, 2007 8:57 am

Quoting TropicBird (Reply 21):
As I recall the YC-15 was the precursor to the C-17... MDC won the competition over Boeing.

Sort of. Changing requirements favored an outgrowth of the YC-15 over the YC-14, but the YC-14 was the better aircraft in meeting the original requirements.

The Air Force belatedly decided it wanted a much larger airlifter than the C-130-sized STOL prototypes it got in the YC-14 and YC-15. Boeing's YC-14 ran rings around the YC-15 in most areas: STOL in particular (and the YC-14 needed only half the runway of a C-130 for the same payload, so it isn't true C-130 could do everything YC-14 could.) Remember YC-14 and YC-15 were developed in a STOL tactical airlift competition to succeed C-130, not a competition to succeed C-141 (which C-17 eventually won.)

But when the Air Force decided it wanted a new strategic airlifter and not a tactical airlifter (probably as headaches with the hangar queen C-5 grew), the STOL capability wasn't as important, and the YC-15 was more easily scaled up to what the Air Force now wanted. So YC-14 ended up as an impressive curiosity and YC-15 led to C-17.

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