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Reply With QuoteIIRC, Chogy mentioned that the only platform he truly feared as an Eagle driver was the F-18 due to it's superior high AOA performance (and, I assume, STR).Originally Posted by GGTharos
The actual, real designers will tell you why they made the aircraft unstable, and it's never 'because we wanted better supersonic control'
Stall speed of AIM-9 happens well after motor burn out in straight flight, and it maintains quite a bit of g capability for a while. In maneuvering flight drag might make it come sooner. Required missile g for terminal maneuvering is generally accepted as 5 * target g, though this is not really a constant and it meant to describe missile capability at peak speed.Required missile g for intercept, that is also science, whether LOS or homing...but simplified formulas I cited helps..missiles has far lower lift than a/c and rely on missile-to-target speed advantage...I graduated on homing decades ago. In book 'Fighter Performance in Practice' actual stall speed of AIM-9 is given at motor burn-out and different Mach.
I haven't heard anyone complaining about the F-16's turning ability.Maneuverability...F-16 also has high T/W with 29 engines, all aerodynamics, but (SQRT span) / weight, crucial for induced drag is bad. Su-27 has almost 18ooo kg empty weight.
The Su-27 has 25000kg of thrust. While this will be slightly reduced at slower speeds, it is still a rocket. Take the hint
It is much better than the F-18A/C/E's in the entire flight envelope, and better than the F-16's in most of the envelope in combat configuration.I wonder whether it’s T/W is better than 18C’s or 16-29’s. All parameters of F-15 are good.
The F-15 is a solid all-round performer, but compared to all of those aircraft it is an energy fighter, not an angles fighter. F-16's and F-18's will out-turn it. This is a well established fact.
If you're in a WVR fight (defined as <5nm ) and you can see your opponent, you can shoot him with an IR missile. If you can see that aircraft, so can your all-aspect missile. The shielding isn't there for dogfight scenarios. It's there to prevent long-range detection.There is also formula for heat dissipation with distance...you can assume that Northrop people didn't make all that trench for nozzle in vane ?
Last edited by GGTharos; 17 Dec 10, at 15:18.
IIRC, Chogy mentioned that the only platform he truly feared as an Eagle driver was the F-18 due to it's superior high AOA performance (and, I assume, STR).
"Yeah. See, we plan ahead, that way we don't do anything right now. Earl explained it to me." - Tremors, 1990
Dear Chogy;
Do you get offended when people refer to you as: "That Lucky Shit."?
I read this entire thread, and have no clue what about 80% of it meant (OK, 90%...), but it was fascinating!
USS North Dakota
Do you get offended when people refer to you as: "That Lucky Shit."?
Being given the keys to an F-15 at 23 years of age was an honor, and I treasure my active duty time. Now, I'd probably pass out at 4G.
When we began DACT with the F/A-18, we thought we ruled the skies, but the reality was that the Hornet ruled its own high-AOA empire. You can see it at an airshow. The Hornet demo emphasizes some pretty extreme high-AOA handling that we could not match, while the F-15 demo was almost always raw power and rocket-like performance. It was a rude awakening to realize we did not own that regime, so we simply avoided it.
I'd be very interested to hear of current DACT missions vs. the super bug. The added thrust and wing area may very well have turned the current F/A-18 into a superior aircraft in terms of the visual fight, but the BVR regime will continue to be dominated by the simple physics of beamwidth and overall antenna area, and that is where the larger aircraft like the F-15 and Su variants shine.
The F-16 was weak in only one area - search and sort - but otherwise, cleansed of iron bombs, it was as nimble as anything in existence at the time.
I think I need to re-emphasize that hyper-maneuverability is no longer the pinnacle of fighter evolution. RCS, acceleration, and stand-off weaponry are now the desired attributes, combined with a level of turning performance that could be considered acceptable.
People might watch an F-22 demo and conclude it wasn't as "cool" as a Sukhoi, but that means little, IMO. I am comfortable with the turning performance of the F-22 as it now exists, which is still far beyond the teen fighters.
Chogy, I find your above statement fascinating. Why didn't he punch out? The reason i ask this is i have an unanswered question as to why Capt. Jeffrey Haney didn't punch out. If you look at the imprint at the crash site it looks like the crash was a controlled landing of some sort because of the imprint left behind. I don't have scientific evidence for this but im beginning to think that maybe there is a phenomenon of pilots being attached to their a/c prefering to go down trying to save their bird than punch out and forsake it. If its unclassified, what are the rules given to you pilots to abandon ship?
He was probably diving at a speed in excess of 600kt. Punch out above that and you're likely to die - supersonic airflow isn't. It's a bit more like a wall as far as the human body is concerned.
Disorientation may also aid you in not realizing you are in mortal danger - you might think you have room to recover, but you don't. You might not think you're in danger at all. There have been pilots who blissfuly spiral-dove themselves into the ground.
The report on that crash will be released in a few months. It may take longer based on the remote location...I don't know if they'll finalize the report based on the evidence already recovered or if they will go back for more in the spring.
I don't know enough about Capt. Haney and I don't want to speculate. In the case I mentioned, if he had ejected, we were fairly confident his downhill vector would have killed him, never mind the flail injuries. What he did was the instinctive action drilled into everybody, which was to roll to the nearest horizon and PULL. I doubt he even considered ejection.
The resulting tape became a training aid for new guys on their night missions over the Gulf of Mexico, where oil rigs and stars can easily blur into sameness, and there is no horizon due to mist or low visibility.
Unless it's changed, the ejection rules were pretty simple. If you are uncontrolled below 10,000' AGL, you eject. If you can control the aircraft, then it becomes a decision-making process. Fire, oddball gear configurations, other factors may require an ejection, and most bases have controlled ejection areas, where the ideal ejection would be relatively slow and in an upright position.
A lot of guys have ridden controllable aircraft into the terrain, and the number of reasons is huge. Each is a sad lesson learned. You have to think through ejection scenarios on the ground, because when confronted with it, hesitation can be fatal.
Over-water: Flail injuries are what created the current horse collar auto-inflating flotation device. Before the horse collar, we had "Mae West" rigs that lived in your vast near the arm pits. Before entering the water, you were supposed to get your mask off and throw it away, because the inlet hose would otherwise be under water. What happened was this - a guy ejected at high speed over water, and both arms were dislocated, broken, and useless. He was unable to disconnect his mask, and drowned. Over land, he would have survived.
The current setup has a salt-water activated flotation collar AND an automatic system to release the mask. The horse collar floats you in a head-up position, mouth well clear of the water, even if unconscious. We hated the thing due to its weight, but recognized that it can save lives.
Horse collar:
The actual, real designers will tell you why they made the aircraft unstable, and it's never 'because we wanted better supersonic control'
Stall speed of AIM-9 happens well after motor burn out in straight flight, and it maintains quite a bit of g capability for a while. In maneuvering flight drag might make it come sooner. Required missile g for terminal maneuvering is generally accepted as 5 * target g, though this is not really a constant and it meant to describe missile capability at peak speed.
I haven't heard anyone complaining about the F-16's turning ability.
The Su-27 has 25000kg of thrust. While this will be slightly reduced at slower speeds, it is still a rocket. Take the hint
It is much better than the F-18A/C/E's in the entire flight envelope, and better than the F-16's in most of the envelope in combat configuration.
The F-15 is a solid all-round performer, but compared to all of those aircraft it is an energy fighter, not an angles fighter. F-16's and F-18's will out-turn it. This is a well established fact.
If you're in a WVR fight (defined as <5nm ) and you can see your opponent, you can shoot him with an IR missile. If you can see that aircraft, so can your all-aspect missile. The shielding isn't there for dogfight scenarios. It's there to prevent long-range detection.
What should I do with you ?? We do not have time to absolve basics...
You can find on net about Typhoon's supersonic maneuverability, is it important and how intensive it is. Newest fighters are not inventors of reduced stability for ss flight (also), B-58, concorde and SR-71 were also, last two were CCV.
Stall speed is function on alpha, it happens whether engine works or not.
I said: "Concerning AMRAAM or any other AAM, especially ones with fast burning motor..I think that chances to catch 4g maneuvering fighter at Mach 2 are very slim at other than close range."
From your "winder" graphs it can be seen that as I said missile own speed is about 2000 ft/s and that after half a dozen seconds either speed or maneuverability drops below ones needed for intercepting Mach 2, 4g target. I believe that AIM-9 has more favorable rocket fuel to warhead+guidance pack weight that AMRAAM and so better balistic charact.
What are sustained g's of Su-27 and F-18 at say 15ooo ft / 0.9 M ?
You think Nortrop built F-23 nozzles invane ?
Here you go: Eurofighter: *Aerodynamic Characteristics
I don't know where you got the conclusion that a subsonic unstable aircraft performs better at supersonic speeds.
On the other hand, you might never be able to reach stall alpha. And?Stall speed is function on alpha, it happens whether engine works or not.
My 'winder' graphs should tell you that is the target is at 4g, it might have trouble evading a 20g missile. 4g is for missiles of the 60's.I said: "Concerning AMRAAM or any other AAM, especially ones with fast burning motor..I think that chances to catch 4g maneuvering fighter at Mach 2 are very slim at other than close range."
From your "winder" graphs it can be seen that as I said missile own speed is about 2000 ft/s and that after half a dozen seconds either speed or maneuverability drops below ones needed for intercepting Mach 2, 4g target. I believe that AIM-9 has more favorable rocket fuel to warhead+guidance pack weight that AMRAAM and so better balistic charact.
The AMRAAM has far more kinematic capability than sidewinder does, and far more intelligence to save its energy against a maneuvering target. While intercept windows for high-speed targets are small, a mach 2 target will have great difficulty evading anything shot in good parameters.
At nominal combat weight? I don't have the charts right in front of me, but I'm reasonably certain the Su-27 would be holding about 6-6.5g while the hornet would be doing less.What are sustained g's of Su-27 and F-18 at say 15ooo ft / 0.9 M ?
Those won't help you much in a dogfight. Period. You're well inside the seeker's ability to see the fuselage at that point, and the exhaust is only a bonus.You think Nortrop built F-23 nozzles invane ?
I'm telling all the time that more unstable a/c at subsonic speeds, less stable is at supers. Centre of pressure moves aft at transs. making a/c too stable if it does not pump fuel aft, deploy glove vanes or if it is not purposely too unstable. Concorde and SR-71 are designed to fly at M 2 & 3 with elevons neutral. F-111 nedeed almost full tail LE down at M2 at hi-alt because sweep also moved a.c. aft.
You will not reach stall alpha only if structural or actuator power limit are already reached. From your graphs it can be seen how missile maneuverability drops with altitude, along its speed. Imagine agility at 40ooo ft or higher at Mach 2 / 4 g targets. And these kinematic data is for missile that is not maneuvering …dissipating energy. If target breaks half a dozen seconds before collision, then proportional nav laws require still higher g.
As I said, missile ballistic range depends on motor total impulse (thrust*time) and dead weight. More electronics, like radar, heavier warhead does not help. IC missile’s disadvantage are relatively blunt nose. Stinger although short effective (acquisition) range has great impulse to weight ratio.
F-18’s sustained g is lower than both F-15/16 except below Mach 0.7 and Su’s is higher.
Both YF-23 and B-2 nozzles can effectively hide IC emissions looking from below.
I see, so it was a simple misunderstanding. Ok.
At 40000' even at mach 2 your aircraft is a slug. A skid-to-turn missile has far better maneuverability than your aircraft will. A missile that is launched head-on (if you're talking tail on, we really don't have much to talk about) won't have much of a problem 'getting in the way'. There's really no disadvantage for the missile itself against a sluggish target. Incidentally, that study shows what happens when you exchange the nose for an ogival one as well as changing the fins (this is the 'variant').You will not reach stall alpha only if structural or actuator power limit are already reached. From your graphs it can be seen how missile maneuverability drops with altitude, along its speed. Imagine agility at 40ooo ft or higher at Mach 2 / 4 g targets. And these kinematic data is for missile that is not maneuvering …dissipating energy. If target breaks half a dozen seconds before collision, then proportional nav laws require still higher g.
As I said, missile ballistic range depends on motor total impulse (thrust*time) and dead weight. More electronics, like radar, heavier warhead does not help. IC missile’s disadvantage are relatively blunt nose. Stinger although short effective (acquisition) range has great impulse to weight ratio.
As for the TWRs and stinger, you're looking at missiles will completely different requirements including launch parameters etc. The stinger is not a worth-while comparison to a sidewinder.
Both the F-15 and Su-27 generate more thrust at max power and zero knots than the F-18 does at M0.9. As such, I really doubt it's able to sustain g better than either of those until you get to really slow speeds, not just below 0.7.F-18’s sustained g is lower than both F-15/16 except below Mach 0.7 and Su’s is higher.
Which isn't a factor in a dogfight. It is a factor for long-ranged detection and MANPADS.Both YF-23 and B-2 nozzles can effectively hide IC emissions looking from below.
That is the question, is aircraft a slug...at 40kft/2M, F-16 can pull 8g, if turn is diving then as you said, missile has to pull 40g. A/c has large wings, missiles usually can not reach alphas where body lift (circular cir.section not box like) is bigger than wing lift (in the F-15's case - above 20 deg), and thrust is out. Imagine MiG-25 sustaining moderate g at 60Kft/2.5M !
I mentioned Stinger because dead weight is reduced with just one pair of control surfaces relying on deflection while in phase during spin and light (1 kg) warhead because of IC homing accuracy i.e. short wavelength of IC radiation.
You forget F-18 is also a lighter a/c, installed thrust with accessory drive clutched (dash 402) at M0.9 SL is 8750 kg while AL-31 at 0M is 10650 kg.
But we saw F-18 is tough because of hi alpha controllability and instantaneous turns. Straight 'turbojets' and straight wings helps in lo speed fight.
The PN constant is huge when the missile is very fast. When the speed is similar it's not as big a factor. As long as the missile can out-g the target and the target is not doing any aggressive out-of-plane maneuvers he should be hit.
It can't. It either turns around or it flies into the missiles.
It is not a good way to compare - small cheap seeker vs. a similar, but actually larger and likely more effective, better cooled one. IMHO. You will find that 'dead weight' is not all that dead if you compare air-launched performance. It all depends on the application.Imagine MiG-25 sustaining moderate g at 60Kft/2.5M !
I don't know where you got those numbers, but really all you need to look at is sustained g. That's what matters. If you want to compare power a little more directly, plane to plane, then it's time to speed or time to altitude when flown using the same schedule.I mentioned Stinger because dead weight is reduced with just one pair of control surfaces relying on deflection while in phase during spin and light (1 kg) warhead because of IC homing accuracy i.e. short wavelength of IC radiation.
You forget F-18 is also a lighter a/c, installed thrust with accessory drive clutched (dash 402) at M0.9 SL is 8750 kg while AL-31 at 0M is 10650 kg.
But we saw F-18 is tough because of hi alpha controllability and instantaneous turns. Straight 'turbojets' and straight wings helps in lo speed fight.
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