Northrop / McDonnell Douglas ATF - YF-23 and EMD F-23
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F-14D said:
I wouldn't want to overstate manoeuvrability courtesy of canards. Certainly the F/A-18F at Paris Air Show this year outperformed the “Euro-Canards” with high alpha manoeuvres and nose authority. And the Rhino was loaded with >2,000 lbs of external stores (AIM-120s and AIM-9Xs) when the Typhoon and Rafale flew only with smoke generators (pussys).
PS on NATF Northrop were playing around with high lift Coanda effect wings. The YF-23A was talked about in terms of BLC wing for high lift as a Senior Citizen solution in one of those Air International X-Planes books. Northrop’s late 80s ATA offer has pretty much exactly the same outer mould line and wing as the X-47B UCAS-D. These wings are very much Coanda effect high lift wings. Etc for the B-2. So the YF-23 might have made a nice NATF without clumsy, high weight, low stealth VG wings.
Overstate the superiority is not reasonable but you gave a wrong example to explain your opnion.
AoA is not everything for air-combat, I dare say the SH's maneuverability is much inferior than Eurofighter, compare with T/W rate, wing load, aerodynamec region, each aspect, Typhoon will go ahead of SH. If you search Google, you will find the Typhoon did some min-radius flip impressively, which only aircraft fitting with TVC can do it.
AoA is not everything for air-combat, I dare say the SH's maneuverability is much inferior than Eurofighter, compare with T/W rate, wing load, aerodynamec region, each aspect, Typhoon will go ahead of SH. If you search Google, you will find the Typhoon did some min-radius flip impressively, which only aircraft fitting with TVC can do it.
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The Typhoon was supposed to have markedly better supersonic manouverability than previous, conventional fighters. This is a lot harder to judge at an airshow...
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Of course manouverability is a very big word when it comes to air combat - what type of manouverability? Knife fight, supersonic, etc. However the context of the discussion I referred to was for dog fight, beyond the merge, WVR manouverability. As you can see in the 2-3 posts before mine. In which case I would bet on Rhino LERXs over Euro-Canards.... and wing generated lift for high alpha control rather than TVC generated directional thrust for high alpha control.
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AGRA said:
The Super Bug has outstanding low speed high AoA, possibly the best around not counting the Raptor in the West and the MiG-29/SU-27 and their derivatives. That's its forte. However, looking at all the aspects of maneuvering for ACM I daresay that Rafale, Typhoon and Gripen will eat it for lunch. It's worthy of note that the USN itself said during development that the Super Bug would not have the all the agility of previous Hornets.
BTW, the X-31 was a canard. It was not a close coupled one like Rafale or Gripen, but more like the decoupled type, like Typhoon.
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overscan said:
A few years back, some Eagles bounced some Typhoons over England. At the time, the Typhoon had not yet been cleared for its full ACM envelope. Still, after less than one complete turn the Typhoons were on the Eagles' tails and could not be dislodged until the "fight" was called off.
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Have uploaded a Northrop video with Paul Metz comments on YF-23 performance.
http://www.youtube.com/watch?v=lVG9xgHefzg
Note in the last moments rare in-flight footage of YF-23 underbelly with famous Thomas Rooney's 'hourglass' markings, removed after first flight.
http://www.youtube.com/watch?v=lVG9xgHefzg
Note in the last moments rare in-flight footage of YF-23 underbelly with famous Thomas Rooney's 'hourglass' markings, removed after first flight.
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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?
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sferrin said:
Well yes but it’s 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.
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AGRA said:
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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Why the 6000 pound drop? Where did it go?
AGRA said:
Unclassified USAF documents give it 20,650 pounds internal and up to 15,865 pounds external.
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LowObservable said:
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.
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sferrin said:
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?
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AGRA said:
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.
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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.
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.
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Sundog said:
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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flateric said:
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:
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sferrin said:
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.
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Sundog said:
You fail to mention that the Eurofighter has even less fuel capacity than the first generation Hornet.
The Super Hornet's primary reason for being is increased fuel capacity over the first generation Hornet, pure and simple.
I would question the value of "supersonic maneuverability" outside of a very narrow defensive context, something that seems largely worthless in modern expeditionary warfare where aerial threats are for the most part absent.
Sundog said:
Hypothetically, you could also get more fuel into a canard delta as compared to a conventional tailed design. In practice, the opposite seems to be true.
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TinWing said:
The function for the increased internal fuel in the Super Hornet is to supply the fuel needed by its F414s, which have a higher fuel burn that the F404s in the F/A-18A-C. The Super Hornet's increase in range was initially attributed to its lower drag and fuel use in the "non cruise" portions of a mission and its larger external fuel tanks. Some of that drag reduction has been lost in actual service. It turns out that the pylons on the production Super Bug have to be angled out, possibly for safety reasons when launching powered ordnance off the inner pylons, and do not align with the airflow. This increases drag, especially when they're loaded. As far as the larger tanks, the F/A-18C/D could have used them as well. According to some sources, the Super Hornet may only exceed the Hornet's unrefueled radius of action just in the ground attack mission and then only by 64nm. As an aside, the longer legged Super Hornet still does not have the range that was supposed to be delivered by the original F/A-18A.
As far as supersonic maneuverability goes, its value is that if you are traveling at a higher speed, you can compensate for your larger radius of turn by having good maneuverability at those higher speeds. For example, in WWII the P-51's turn radius was smaller than that of the Me-262. However, the 262 had good maneuverability at its speed, so what it could do was use its superior speed to fly around its larger radius turn faster than the -51 could fly around its tighter turn, which allowed the 262 to stay on the -51's tail at the completion of the maneuver. Same principle would apply to a supercruising vehicle, vs a transonic aircraft, plus it would be useful when encountering an aircraft capable of matching your speed performance. Speed is life!
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Fuel fraction (usually considered in terms of fuel/mass with full internal fuel and no weapons) is a big factor in range, of course. But there's also engine cycle, and the degree to which you need to use afterburning. The F-22 has near-pure-jet engines (bad) but does not need A/B except to accelerate or for extreme maneuver (good).
Since the Super Hornet is basically a scale-up of the Hornet, with about the same internal fuel fraction and slightly lower-bypass engines, the main reason that the range is better is indeed its external tanks. Both the Classic and the Super can carry 480 USG tanks under the wings, but the Classic can only carry a 330 USG tank centerline and the Navy never wanted to mix tanks.
Finally, general design and configuration makes a difference in drag with big external loads. Supposedly, for example, the Typhoon is reasonably efficient and flies well with a large load, which gives it a better range than (say) an F-16.
Since the Super Hornet is basically a scale-up of the Hornet, with about the same internal fuel fraction and slightly lower-bypass engines, the main reason that the range is better is indeed its external tanks. Both the Classic and the Super can carry 480 USG tanks under the wings, but the Classic can only carry a 330 USG tank centerline and the Navy never wanted to mix tanks.
Finally, general design and configuration makes a difference in drag with big external loads. Supposedly, for example, the Typhoon is reasonably efficient and flies well with a large load, which gives it a better range than (say) an F-16.
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However, part of the reason for the F-22s low bypass ratio engine is also due to it being optimized for supersonic cruise, versus the higher bypass turbofans which aren't. I think the biggest problem was they, LM, either thought advanced technology would limit their weight growth into production or they simply underestimated how much weight the Raptor would gain going into production. Or was it a case, as so often happens, where the USAF ended up making L-M put more into the package as it transitioned from a development aircraft to a production aircraft?
flateric said:
Yes, absolutely fascinating. Thank you as well.
However, can anyone tell me why, on page 41, it seems to indicate that WOOL is a major component of the F-117? I hope it's being used as a blanket
term for all the fibres listed below? This seems a good explanation, but they also go to the extent of suggesting the section refers to "Fibres, Natural and synthetic" Have we found the real secret of stealth?
AGRA said:
Where did you get the number as only 0.29 for F-22A or YF-22?
The correct calculation of fuel fraction is internal fuel capability/weight empty.
so even the internal fuel of F-22 down to 10 ton, the empty weight up to 17 ton. the fuel fraction also will be reach 0.59!! You put the wrong number not is on basic digit but on tens digit!
Sundog said:
My dear friend:
you'd better know what was you said equal factually is dissimilar.
foreplan could be smaller than horizontal stabilizer so the structual weight will be reduced.
foreplan will give a smaller balanced drag than conventional horizontal stabilizer, no matter where the barycenter you put.
the area of delta wing adapt to the foreplan will be bigger than conventional layout so give more lift the maneuver needed.
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]
Yes, absolutely fascinating. Thank you as well.
However, can anyone tell me why, on page 41, it seems to indicate that WOOL is a major component of the F-117? I hope it's being used as a blanket term for all the fibres listed below? This seems a good explanation, but they also go to the extent of suggesting the section refers to "Fibres, Natural and synthetic"
Have we found the real secret of stealth?
[/quote]
am i right in thinking that the RAM covering on the F-117 is a kind of fabric? i seem to remember seeing some news footage of the F-117 brought down in kosovo, that showed pieces of fabric hanging loose from the wreckage of the wings. also, wasn't this stuff also supposed to be impregnated with all the nasty chemicals that caused the labour problems at lockheed?
cheers,
Robin.
Yes, absolutely fascinating. Thank you as well.
However, can anyone tell me why, on page 41, it seems to indicate that WOOL is a major component of the F-117? I hope it's being used as a blanket
term for all the fibres listed below? This seems a good explanation, but they also go to the extent of suggesting the section refers to "Fibres, Natural and synthetic" Have we found the real secret of stealth?
[/quote]
am i right in thinking that the RAM covering on the F-117 is a kind of fabric? i seem to remember seeing some news footage of the F-117 brought down in kosovo, that showed pieces of fabric hanging loose from the wreckage of the wings. also, wasn't this stuff also supposed to be impregnated with all the nasty chemicals that caused the labour problems at lockheed?
cheers,
Robin.
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As I've stated before, canard aircraft tend to be lower cost, because they tend to have lower weight, for the mission, precisely because you don't need the tail structure that a conventional aircraft requires.
However, most modern fighters are unstable. As such, the canard is usually sized to push the nose down at high alpha. That means the canard is working against the wing. Whereas with the conventional tail it provides lift to keep the nose down in the same regime. As such, it turns out there are areas of the envelope where the canard can't trim the aircraft as effectively because the conventional tail offers advantages in sizing in this part of the regime. This is one of the reasons why Lockheed's F-35 went from a canard design to a conventional tail. There are other areas of the envelope where the conventional tail is better as well.
However, for many nations, cost is the number one driver, which was one of the primary design drivers for all of the new European Fighters having been built as canards instead of conventional tail configurations.
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