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Author Topic: Northrop/McDonnell Douglas YF-23 and EMD F-23  (Read 469656 times)

AGRA

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #90 on: December 14, 2007, 08:45:56 pm »
Just to talk a bit more about what a F-23A might have meant one of the most significant failings of the F-22A is its failure to meet the requirement for fuel for effective supercruising as established by the Advanced Tactical Fighter (ATF) program. ATF required a fuel fraction of 0.39 or at least 0.35 to have enough fuel to power the engines (F119 or F120s) for enough super cruising. F-22A only has a fuel fraction of 0.29 significantly reducing the range it can supercruise. This makes its supercruise capability just a lower engine IR signature way of dashing at supersonic speeds or reduces radius from the planned 800 NM to the actual 410 NM. Considering the YF-23 is a bigger plane than the YF-22 and has significant area ruling is it feasible that an F-23A could have had the higher fuel fraction and less supersonic drag required to meet the original ATF supercruise requirement?

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #91 on: December 14, 2007, 09:13:21 pm »

The YF-22 had way more fuel than the F-22A.
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AGRA

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #92 on: December 14, 2007, 11:49:37 pm »
The YF-22 had way more fuel than the F-22A.

Well yes but itís an unfair comparison. The YF-23 had an internal fuel capacity of 24,000 lbs compared to 25,000 lbs for the YF-22. The process of going from YF-22 to F-22A has seen internal fuel drop to 18,000 lbs.

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #93 on: December 15, 2007, 05:21:14 am »
The YF-22 had way more fuel than the F-22A.

Well yes but itís an unfair comparison. The YF-23 had an internal fuel capacity of 24,000 lbs compared to 25,000 lbs for the YF-22. The process of going from YF-22 to F-22A has seen internal fuel drop to 18,000 lbs.

Yep.  My theory is they decided they're not going to have to go tankerless as long cruising around in badguy territory so they cut down the fuel load to enable even higher performance.  Granted, the production engines contribute to that but the F-22A is considerably slimmer than the YF-22.
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Offline LowObservable

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #94 on: December 15, 2007, 07:04:35 am »
Why the 6000 pound drop? Where did it go?

Offline Rosdivan

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #95 on: December 15, 2007, 07:52:40 am »
The YF-22 had way more fuel than the F-22A.

Well yes but itís an unfair comparison. The YF-23 had an internal fuel capacity of 24,000 lbs compared to 25,000 lbs for the YF-22. The process of going from YF-22 to F-22A has seen internal fuel drop to 18,000 lbs.

Unclassified USAF documents give it 20,650 pounds internal and up to 15,865 pounds external.

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #96 on: December 15, 2007, 09:03:16 am »
The YF-22 had way more fuel than the F-22A.

Well yes but itís an unfair comparison. The YF-23 had an internal fuel capacity of 24,000 lbs compared to 25,000 lbs for the YF-22. The process of going from YF-22 to F-22A has seen internal fuel drop to 18,000 lbs.

Unclassified USAF documents give it 20,650 pounds internal and up to 15,865 pounds external.

The -1 says about 18,500 lbs.
"DARPA Hard"  It ain't what it use to be.

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #97 on: December 15, 2007, 09:05:33 am »
Why the 6000 pound drop? Where did it go?

If you do some side-by-side comparisons of the YF-22 and F-22A you can see that the rear ventral area, lower fuselage corners, and top of the fuselage have lost some volume.  Like the thing went on a diet.
"DARPA Hard"  It ain't what it use to be.

AGRA

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #98 on: December 15, 2007, 03:51:14 pm »
Yep.  My theory is they decided they're not going to have to go tankerless as long cruising around in badguy territory so they cut down the fuel load to enable even higher performance.  Granted, the production engines contribute to that but the F-22A is considerably slimmer than the YF-22.

No the fuel was lost as weight cutting measures during the development. The F-22A has not gained any performance because of it and has lost the ATF RFP radius of action. The whole point of the ATF was to have a stealthy, supercruising aircraft which combined with the latest avionics would be a super air combat platform. Aircraft limitations have seen the fuel cut so it can only supercruise to a radius half that required in the RFP. 410 Nm vs 750-800 NM. This is not a recasting of the RFP due to changed circumstances but a failure of the development team to produce the goods.

My question is could the F-23 have retained the RFP fuel and radius levels?

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #99 on: December 15, 2007, 07:06:33 pm »
Yep.  My theory is they decided they're not going to have to go tankerless as long cruising around in badguy territory so they cut down the fuel load to enable even higher performance.  Granted, the production engines contribute to that but the F-22A is considerably slimmer than the YF-22.

No the fuel was lost as weight cutting measures during the development. The F-22A has not gained any performance because of it.

How can you install more powerful engines (YF119s were kinda wimpy compared to the production models), lose 7,000lbs of fuel, slim up the airframe, cut the vertical tail size damn near in half, and NOT gain any performance?  You can't.  Which is why the YF-22 only supercruised at Mach 1.43 with the YF119s and the F-22A is good for better than Mach 1.7.
"DARPA Hard"  It ain't what it use to be.

Offline Sundog

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #100 on: December 15, 2007, 11:45:48 pm »
Back to the OT:Super Hornet performance. It was known since it's development the Super Hornet would not have the capability of the Eurofighter. In fact, the most capable version of the SH studied was the canard/arrow wing variant which itself only possessed 90% of the performance of the Eurofighter.

As I've said before, all things being equal, a conventional tail aircraft has better high AOA control than a canard aircraft in certain parts of the envelope. The main reason for going with canards is you can make a smaller airframe for a given mission then a conventionally tailed aircraft, which means lower weight and, therefore, lower cost.

As for the F-22 vs the YF-22, don't forget they made major changes to the wing and tail design, such as reducing the L.E. sweep and increasing the AR for the wing of the production version. They also trimmed some weight by getting rid of the separate airbrake and going with a system similar to the YF-23's that uses the primary flight control surfaces to create aerobraking. Also, in Picarillo's book on the ATF program, he states that the minimum fuel fraction required for efficient supercruise is .25 and that the production version of he Raptor would be just under that

What I find interesting is how the production version of the F-23 would have had half shock cone inlets instead of the 3D oblique shock inlets and how they moved the engines closer together.

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #101 on: December 16, 2007, 06:04:00 am »
What I find interesting is how the production version of the F-23 would have had half shock cone inlets instead of the 3D oblique shock inlets and how they moved the engines closer together.

Maybe they hadn't quite figured out how to make the half-cones stealthy enough while the YF-23 was being designed or maybe they discovered the inlets weren't as efficient as they thought.  Would be interesting to know.
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Offline flateric

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #102 on: December 16, 2007, 09:09:35 am »
Unclassified USAF documents give it 20,650 pounds internal and up to 15,865 pounds external.

Rosdivan, one of the best pdf files I've seen in the last years) Thanks a lot!
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stealth, more than a few of them truly technically ignorant and proud of it." Sherm Mullin, Skunk Works

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #103 on: December 16, 2007, 09:31:45 am »
Unclassified USAF documents give it 20,650 pounds internal and up to 15,865 pounds external.

Rosdivan, one of the best pdf files I've seen in the last years) Thanks a lot!

That's the document I was thinking off.  (Must be getting senile as I could have swore it was ~18,500  :-[ )  Looking at the B-1's right now.  Apparently it was designed to carry 6 3500-liter external tanks (obviously they never went forward with them).  Lots of interesting information in there.  For instance the B-2 has some sort of laser on the back end.  My guess it's a IIR "dazzler" but could be something more mundane like a laser communication link.  Probably obvious but chop off part of the link and you can get them all:

http://0x4d.net/files/AF1/



« Last Edit: December 16, 2007, 10:02:37 am by sferrin »
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AGRA

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #104 on: December 16, 2007, 10:01:55 pm »
How can you install more powerful engines (YF119s were kinda wimpy compared to the production models), lose 7,000lbs of fuel, slim up the airframe, cut the vertical tail size damn near in half, and NOT gain any performance?  You can't.  Which is why the YF-22 only supercruised at Mach 1.43 with the YF119s and the F-22A is good for better than Mach 1.7.

Ya we are at cross purposes here. I meant in terms of the performance speced by the RFP. Which is why they needed to make the changes in order to meet the RFP performance spec (supercruise over Mach 1.6). Radius of action was the loser.