Why fighters primary attributes changed the way they did?

[Vanessa1402]

The later F-15/F-16 programs were a "have your cake and eat it too" solution where advanced engines and aerodynamics allowed planes to have both excellent horizontal and vertical maneuverability. They were both conceived and designed before all aspect and off-boresight AAM were in production and before BVR missile technology had demonstrated serious combat potential, i.e., when energy maneuver was still the best approach. .

So in conclusion, with agile WVR missile then turn rate are more important, with cannon only then acceleration are more important?

 

[Ronny]

On topic of dogfight: NASA did some test between the X-31 with post stall technology against operational fighter at that time, and they find that while F-14 and F-18 get totally demolished in close combat, F-15 and F-16 actually achieve positive kill ratio due to their acceleration

 

[uk 75]

The Typhoon evolved into a missile and radar platform but it seems pretty agile
It has been claimed with its full weapons fit to be the best fighter available in production. (F22 excluded therefore)

 

[BB1984]

The later F-15/F-16 programs were a "have your cake and eat it too" solution where advanced engines and aerodynamics allowed planes to have both excellent horizontal and vertical maneuverability. They were both conceived and designed before all aspect and off-boresight AAM were in production and before BVR missile technology had demonstrated serious combat potential, i.e., when energy maneuver was still the best approach. .

So in conclusion, with agile WVR missile then turn rate are more important, with cannon only then acceleration are more important?

I think it's more complicated overall, though you can make some general statements like "As WVR missiles become more capable and all aspect, the important thing becomes how fast you can get the nose of the aircraft pointed in the right direction to fire the missile, and, with off boresight missiles becoming more prevalent, even that is becoming less important."

This is a summary chart from a blog post from Elements of Power; the whole article is worth a look and is here. AA refers to "All Aspect", i.e., it can be fired at a plane from any angle, not just from behind.

 

[Cannonfodder43]

1. IJN tactics were ironically energy fight-centric. The ability to do a turn fight doesn't change that fact. Later on, they simply didn't have this choice anymore.
Consequently, A6M wasn't optimized just for agility. It was optimized(put on a diet) for literally everything. Compare it with contemporary(1940-41-42) carrier-borne fighters - it is not just "agile"(a5m was more agile, and biplanes were more agile still). it was faster, could easily out-accelerate and outclimb all of them while being heavier armed. And flew further with all that.
2. A6m became seriously more vulnerable than its opposition by the second half of 1942 - i.e. it was the result of its development (and especially the development of its contemporaries) and not of the original concept. In the end(1945), it'd obtained just as much or even more armor&survivability measures than most western fighters - it just happened really late, and crippled it more due to the simple lack of engine power and continuing service on the frontlines.
3. For a 1940 fighter, it was decently armed. Then it gradually descended to "average" levels(by ~1943), then in 1944-45 bounced up once again (reaching 3HMG+2 20mm by the end of the war).

Overall A6M is very widely misunderstood as some sort of wrong-designed air display plane. It was not. It just got far behind the curve(hence speed race) due to lack of timely engine replacement.

I'm going to differ with your interpretations rather than your facts. Yes, the A6M was long-ranged, but that's a fundamental design driver in carrier aircraft, and ultimately it was more agile than the aircraft it opposed, even if was less agile than the aircraft that preceded it (a point that was generally true, rather than specific to the A6M). And if it was more heavily armed than the A5M, it had very limited ammunition, 60rpg, for its two 20mms and after that it was down to the same two 7.7mms as the A5M, while the Ki-43, in all but the very first production marque, had either one or two 12.7mms. WRT protection it was significantly behind the curve wrt self-sealing tanks from pretty much the onset of the war.

Based on new contemporary research, what @Ainen listed is both correct in fact and interpretation.

Shortly after the Second Sino-Japanese war began while the IJNAS pilots did dogfight, there quickly was a change over to hit and run and slashing attacks. The Zero was the product of operational experience and demands that placed more emphasis on range than dogfight performance based on experience in China. The Zero had excellent low speed agility to try and meet stringent requirements but even that was not enough to meet the IJN's requirement that it be as good as or better than the A5M in this regard but in the end that was accepted. By comparison the Ki-43 and the IJAAS were the more dogfight doctrinaire service as shown with the Oscar which had virtually no room for meaningful upgrades compared to the more balanced Zero.

The Zero was certainly a dogfighter but not at the expense of virtually everything else like the Oscar. In fact as the video I linked below talks about, one American criticized the Zero pilots for not choosing to tail-chase instead of hit and run attacks.

By 1941 the Zero's armament was average with the two 20mm's having limited ammo and muzzle velocity, but for 1940, it was certainly on the heavier side of things. And it was improved as time went on.

And lastly, in regards to pilot protection and self-sealing fuel tanks it should be noted that when the Zero was designed and accepted into service in 1940 pilot armor was virtually not a thing nor self-sealing tanks. Only by the end of 1940 were the German's putting armor plate for the BF-109's and self-sealing tanks in the 109F models by 1941. Many of the U.S fighters also did not have self-sealing tanks or armor. What made the Zero and the rest of the IJNAS unique however was their tardy adoption of such measures by 1942/43, but to claim that by its introduction it was behind the curve is false.

View: https://www.youtube.com/watch?v=ApOfbxpL4Dg&t=5107s&ab_channel=Drachinifel

This informative video busts quite a few myths about the Zero. In regards to the discussion on hand,

49:55 The claim that Japanese pilots preferred tail-chasing dogfights and tactics discussion
1:19:01 Armament
1:33:00 Origins to the Zero's vulnerability and history of aircraft protection features

 

[DWG]

Contrary to what was written above for the LWF, Boyd was only part of a team as far as the requirements goes and was in no position to dictate anything. That is one reason why the 1971 LWF requirements were for an all weather in any light conditions fighter - even Boyd eventually agreed the radar was a good thing.

The point isn't that Boyd literally wrote the requirements, but that he and the Fighter Mafia created a context in which a lightweight dogfight optimised dayfighter was the objective.

 

[DWG]

View attachment 665698

If he thinks the operational utility of sustained turn rate is an energy conserving turn, and that that was less important after the introduction of all-aspect missiles, there's a generation of air combat operational research guys and fighter designers would like a word.

All aspect SRAAMs increase the importance of not entering the merge, and high speed sustained turn rate is what lets you do that. (Not losing energy in the turn is important, but it's not why turn rate is important).

 

[DWG]

By 1941 the Zero's armament was average with the two 20mm's having limited ammo and muzzle velocity, but for 1940, it was certainly on the heavier side of things. And it was improved as time went on.

And lastly, in regards to pilot protection and self-sealing fuel tanks it should be noted that when the Zero was designed and accepted into service in 1940 pilot armor was virtually not a thing nor self-sealing tanks. Only by the end of 1940 were the German's putting armor plate for the BF-109's and self-sealing tanks in the 109F models by 1941. Many of the U.S fighters also did not have self-sealing tanks or armor. What made the Zero and the rest of the IJNAS unique however was their tardy adoption of such measures by 1942/43, but to claim that by its introduction it was behind the curve is false.

I'm judging it from the British perspective, and in comparison to Spitfire and Hurricane (etc) it was definitely behind the armament and (to a lesser degree) protection curves. Doubly so if you count by time from the outbreak of national involvement in aerial combat rather than date (1937 for Japan, 1939 for the UK)

Decision to adopt 8x .303 as standard armament: 1934
Spitfire Armament: 8 .303 from 1936, 4 .303 and 2x20mm from summer 1940 (in aircraft with the B wing).
Hurricane Armament: 8 .303 from 1935, trials with 2x20mm 1939, Mk IIB with 12x .303 trials Summer 1940, production Feb 41, Mk IIC with 4x20mm trials summer 1940, production Feb 41)
Spitfire/Hurricane pilot armour: refitted fleet-wide Summer 1940
Spitfire self-sealing tanks: refitted fleet-wide Summer 1940 (can't find a reference for the Hurricane, but probably similar)

And of course by the outbreak of war we'd had several requirements for cannon fighters, even if only the Whirlwind and Beaufighter proceeded to production.
Whirlwind 4x20mm, first flight 1938, entry into service summer 1940
Beaufighter 4x20mm + 6x .303, first flight 1939, entry into service summer 1940

Incidentally the US amended the orders for the P-39C to require armour and self-sealing tanks in September 1940. Even the people who weren't at war had gotten the message.

 

[overscan (PaulMM)]

The later F-15/F-16 programs were a "have your cake and eat it too" solution where advanced engines and aerodynamics allowed planes to have both excellent horizontal and vertical maneuverability. They were both conceived and designed before all aspect and off-boresight AAM were in production and before BVR missile technology had demonstrated serious combat potential, i.e., when energy maneuver was still the best approach. One could argue that they should have looked ahead to future missile development and possibly taken a modified approach, but OTOH missile engineers had over-promised and under-delivered for decades so maybe that's forgivable.

Absolutely and Boyds experience in the 50s and 60s was of technology that was demonstrably junk without exception. The radars were almost dead weight and combat was in reality a 99% pure visual affair. There is no point looking back 50 years later and saying but why didn't they see the digital revolution coming etc - pointless because at the time they had a valid point.

Some technologies proved disappointing, most often when pressed into situations they weren't designed for. The issues were more often doctrinal than technical, though obviously the 1970s and 1980s revolutionized avionics reliability.

Contrary to what was written above for the LWF, Boyd was only part of a team as far as the requirements goes and was in no position to dictate anything. That is one reason why the 1971 LWF requirements were for an all weather in any light conditions fighter - even Boyd eventually agreed the radar was a good thing.

This is absolutely not correct. The LWF requirements were specifically for a day fighter demonstrator. Each contractor fitted a range-only radar to support gun and Sidewinder testing, but no all weather capability was asked for or provided in the prototypes.

When LWF became ACF, a production program, is when the Air Force debated at length what kind of equipment to install. Factions in favour of F-18 levels of avionics and Sparrow missiles argued with some who wanted to preserve the pure day fighter with minimal avionics. A reasonably austere fit with a design-to-cost radar and no Sparrow was the compromise in the end. When technology matured further, the F-16C etc added more and more capability.

It also wasn't Boyd that went out of their way to keep AIM-7 off the F-16A.

A main driver was cost - lower cost = higher numbers and sortie rate. It was also designed to be easy to maintain with a quick turnaround time. Also that cost is probably also only going to buy you an F-16 / Mirage sized airframe at the end of the day.

The major drivers for no Sparrow were lower cost, less weight, and making sure it didn't have too much overlapping capability with the F-15. Not in that order.

 

[BB1984]

View attachment 665698

If he thinks the operational utility of sustained turn rate is an energy conserving turn, and that that was less important after the introduction of all-aspect missiles, there's a generation of air combat operational research guys and fighter designers would like a word.

All aspect SRAAMs increase the importance of not entering the merge, and high speed sustained turn rate is what lets you do that. (Not losing energy in the turn is important, but it's not why turn rate is important).

Given that the chart is talking about tactics/characteristics before and after all aspect SRAAMs, I assume the chart is relative importance of characteristics for WVR, which I also assume you would refer to as "during/after the merge"

If what you mean by "avoiding the merge" is firing missiles BVR and then avoiding WVR entirely, then there's more than one way to do that. Yes a sustained turn is one way to try and avoid a merge, but stealth or other methods work as well.

• It's hard to argue that the F-35, for instance, isn't trying to avoid a merge via stealth much more than sustained turn rate. IIRC an F-16 will handily turn inside an F-35. Turning a stealth aircraft also brings up signature issues for planes with "bow tie" stealth vs. "all around" stealth.
• The Split S is an example of a 180 change of direction without any sustained turn
• Any significant advantage in radar and missile range for BVR gives more time/space for avoiding the merge

 

[Basher54321]

This is absolutely not correct.

Boyd was part of a study group headed by a Brigadier Gen Ken Chapman so he had to accept any compromises regarding what the LWF was going to be - which is correct at least according to someone who worked with Boyd and was a USAF Chief System Engineer on the LWF so will have to defer to him.

The original LWF goals from that group apparently included:

Mission Essential Avionics (Clear Weather, day conditions) with capability to be upgraded later to all-weather & all-light conditions.


Obviously the LWFs were initially tech demonstrators to show off new technology for future fighters.

Several people from the program have stated to me the reasons for no Sparrow - so pretty certain it could have been on there much earlier than 1989/90 had they decided to (and given a similar perceived capability to the Cold War era MirageF1/2000 and MiG-29.)

 

[BB1984]

This is absolutely not correct.

Boyd was part of a study group headed by a Brigadier Gen Ken Chapman so he had to accept any compromises regarding what the LWF was going to be - which is correct at least according to someone who worked with Boyd and was a USAF Chief System Engineer on the LWF so will have to defer to him.

The original LWF goals from that group apparently included:

Mission Essential Avionics (Clear Weather, day conditions) with capability to be upgraded later to all-weather & all-light conditions.


Obviously the LWFs were initially tech demonstrators to show off new technology for future fighters.

Several people from the program have stated to me the reasons for no Sparrow - so pretty certain it could have been on there much earlier than 1989/90 had they decided to (and given a similar perceived capability to the Cold War era MirageF1/2000 and MiG-29.)

The proposed naval variants of the F-16 had the Sparrow from the start though, to be fair, some of these proposals were major modifications of the original design.

 

[overscan (PaulMM)]

This is absolutely not correct.

Boyd was part of a study group headed by a Brigadier Gen Ken Chapman so he had to accept any compromises regarding what the LWF was going to be - which is correct at least according to someone who worked with Boyd and was a USAF Chief System Engineer on the LWF so will have to defer to him.

The original LWF goals from that group apparently included:

Mission Essential Avionics (Clear Weather, day conditions) with capability to be upgraded later to all-weather & all-light conditions.


Obviously the LWFs were initially tech demonstrators to show off new technology for future fighters.

Several people from the program have stated to me the reasons for no Sparrow - so pretty certain it could have been on there much earlier than 1989/90 had they decided to (and given a similar perceived capability to the Cold War era MirageF1/2000 and MiG-29.)

The proposed naval variants of the F-16 had the Sparrow from the start though, to be fair, some of these proposals were major modifications of the original design.

Adding Sparrow added weight and cost - the Vought / GD NACF proposals make that clear. It was something the Navy wanted.

 

[Archibald]

The funny thing about the "Deal of the Century" was that the 348 F-16s had no Sparrows when Italian F-104S had Sparrows...

 

[overscan (PaulMM)]

This is absolutely not correct.

Boyd was part of a study group headed by a Brigadier Gen Ken Chapman so he had to accept any compromises regarding what the LWF was going to be - which is correct at least according to someone who worked with Boyd and was a USAF Chief System Engineer on the LWF so will have to defer to him.

The original LWF goals from that group apparently included:

Mission Essential Avionics (Clear Weather, day conditions) with capability to be upgraded later to all-weather & all-light conditions.

You are talking about the reconstructed LWF requirements chart in Herb Hutchinson's book, right? I presume he didn't have access to the original and reconstructed it from other documents. I'm not completely convinced that line was actually in the final LWF request document, though you'd need a copy to settle it for sure.

I have a copy of one of the actual LWF responses in front of me, and it describes a range-only radar fit, while suggesting for the prototype to not even bother with that, just a beacon interrogator / transponder system for gunnery trials. There is no mention anywhere of capability to fit all-weather equipment, which seems a strange omission to make if it was a requirement. The YF-16 nose was too small to fit a useful radar, and Boeing's design was even worse, very thin "needle" nose.

Obviously the LWFs were initially tech demonstrators to show off new technology for future fighters.

Several people from the program have stated to me the reasons for no Sparrow - so pretty certain it could have been on there much earlier than 1989/90 had they decided to (and given a similar perceived capability to the Cold War era MirageF1/2000 and MiG-29.)

Of course it was possible to fit Sparrow in 1975. It was mainly omitted to protect the F-15.

 

[DWG]

View attachment 665698

If he thinks the operational utility of sustained turn rate is an energy conserving turn, and that that was less important after the introduction of all-aspect missiles, there's a generation of air combat operational research guys and fighter designers would like a word.

All aspect SRAAMs increase the importance of not entering the merge, and high speed sustained turn rate is what lets you do that. (Not losing energy in the turn is important, but it's not why turn rate is important).

Given that the chart is talking about tactics/characteristics before and after all aspect SRAAMs, I assume the chart is relative importance of characteristics for WVR, which I also assume you would refer to as "during/after the merge"

If what you mean by "avoiding the merge" is firing missiles BVR and then avoiding WVR entirely, then there's more than one way to do that. Yes a sustained turn is one way to try and avoid a merge, but stealth or other methods work as well.

• It's hard to argue that the F-35, for instance, isn't trying to avoid a merge via stealth much more than sustained turn rate. IIRC an F-16 will handily turn inside an F-35. Turning a stealth aircraft also brings up signature issues for planes with "bow tie" stealth vs. "all around" stealth.
• The Split S is an example of a 180 change of direction without any sustained turn
• Any significant advantage in radar and missile range for BVR gives more time/space for avoiding the merge

A document that only considers the within visual range fight is misleading for the needs of this discussion, because aircraft design necessarily considers the whole spectrum of air to air combat, and the way in which the aircraft in question intends to go about that - which is where the operational research guys come in, because they can model ways to fight before anyone ever includes an airframer in the discussion. And what they were telling us for the generation of fighters that includes F-22, Typhoon, Rafale and Gripen was that fighters should be designed to win the fight from beyond visual range and avoid the merge into the within visual range fight.

There are indeed multiple ways to approach that, and all four fighters were designed to take advantage of one or more of them: Stealth-enabled bushwhack for the F-22, datalink-enabled bushwhacking for all of them, but F-22 and Gripen in particular, supercruise-enhanced missile kinematics for Typhoon and F-22, and high speed sustained turn rate for all of them. It's also why all three of the European designs considered AIM-120 a stopgap until Meteor arrived. It's also the reason Typhoon and Rafale emphasized front-aspect stealth, because that gave them a stealth-enabled bushwhack even if they didn't have all-aspect stealth.

WRT the Split-S, it's not applicable to this particular discussion as the object isn't to reverse direction, it's to break port or starboard as fast and as hard as you can, _while maintaining a radar track on the other guy_. Which limits you to a bit more than a ninety degree turn, depending on how far to the side you can turn your radar antenna. That radar track is essential because you have to keep illuminating the other guy if you're using a semi-active missile like AIM-7 or Skyflash, or because you need to keep updating the inertial phase of AIM-120 or Meteor.

 

[Sundog]

This is a bit of a mess. If I get time, I'll refine it further in the future. I'll get to Part 2 this weekend.

Part 1) I'm going to try and answer your original question from more of an aircraft design/technology and doctrine perspective. But in a Cliff Notes sort of way.

The first thing to know is;

The mission defines the aircraft.

You figure out what mission you need to fly, based on what the end goal is, and apply or develop the needed technology to accomplish the mission. Of course, those two don't always mesh, so the mission goals do have to be redesigned to meet the available technology at times. As with everything in aircraft design, it's always a trade off. There are cases where aircraft are used for missions they weren't designed for because sometimes existing aircraft designs come close enough to meeting the stated requirements, or it's all you have at the moment to perform the mission.

As I'm sure you're well aware, aircraft were first used regularly by all the nations engaged in war in aerial combat in WW1. They were first used for observation/reconnaissance. As the pilots from either side encountered each other they started using their pistols to try and shoot the other pilot. As a result, to deny the opposing forces the ability to report on them, they began developing aircraft with guns mounted to them, both flexible (aim-able) and fixed. As a result, they learned about the various advantages and dis-advantages of relative maneuverability and through trial and error (Blood and lost lives) developed the basic tactical doctrine of aerial combat, mainly be the Germans, in the development of basic fighter tactics such as Dicta Boelcke by Oswald Boelcke, which state;

1. Try to secure advantages before attacking. If possible, keep the sun behind you.
2. Always carry through an attack when you have started it.
3. Fire only at close range, and only when your opponent is properly in your sights.
4. Always keep your eye on your opponent, and never let yourself be deceived by ruses.
5. In any form of attack it is essential to assail your enemy from behind.
6. If your opponent dives on you, do not try to evade his onslaught, but fly to meet it.
7. When over the enemy's lines never forget your own line of retreat.
8. For the squadron: Attack on principle in groups of four or six. When the fight breaks up into a series of single combats, take care that several do not go for the same opponent.

As such, the main drivers of aerial combat advantages at the time were speed, altitude, the ability to out maneuver the opponent and secure a favorable firing position. However, one of the most important lessons learned and is still one of the driving factors of aerial combat is "First look, first kill." The pilot that sees the enemy first has the advantage. IIRC, most aerial kills were the result of surprise, the other pilot never saw their attacker coming. It's a low percentage of kills that were the result of dog fighting.

So aerial combat was becoming more about controlling the sky by shooting down enemy aircraft attacking your forces and using your fighters to provide cover for the ground forces. As the interwar years went on, technology advanced rapidly and aircraft were getting faster and stronger. Also, tactics were changing. There was a new idea to use large aircraft to drop bombs on opposing forces, the advent of the bomber, and the development of more advanced tactics, such as the finger four formation. The latter of which was finely honed by the early Luftwaffe over the skies of Spain in the late thirties and is still one of the basic formations used to this day.

The doctrines of many air forces were tested in the crucible of WW2 and those who didn't adapt didn't fare very well. Japan and Italy had good aircraft at the beginning of the war, but infighting and constantly changing requirements lead them down many paths without anything better to replace their early war types and/or limited resources preventing them from developing follow on aircraft that could compete with the aircraft developed by the allies. Also, they had to contend with large bombers, which lead them to having to develop aircraft with heavy armament to bring them down and also forced the allies to change their doctrines when they realized the bombers couldn't protect themselves and needed to be escorted. Or they had to bomb at night. This was a good example of how advancing technology and changing mission doctrine changed the face of warfare. The change to night warfare and the advent of RADAR technology being a perfect example.

The thirties and early forties lead to rapid development of propulsion, armament, structures, and aerodynamics. There was even some advanced stability and control development in the form of flying wings and from the agility standpoint, the Curtiss XP-55. The ideas behind the latter didn't really workout until the advent of the F-16 and RSS control systems through the use of FBW technology.

Now, while I always harp on the "mission defines the airplane, not the other way around," one of the greatest fighters of all time, IMHO, was more the result of circumstance, than anything truly defined by the nation that ended up using it the most. That would be the P-51. It was designed for the British. They were looking for aircraft companies in the U.S. to build P-40s for them, but when they asked North American to build P-40s for them, they said, "no." However, they did say they would design a new fighter for them. The result was the NA-73X. The first aircraft, to the best of my knowledge, designed that was completely mathematically defined using advanced conic sections/lofting. It has a laminar flow airfoil, which allows it to go fast while being thick to could carry a lot of fuel internally. The U.S. didn't want it, because they had the P-47 and the P-38 and they were leery of a plane designed by the son of German emigres. But the British persisted and got it into limited production and they figured it would have even better performance with a Merlin engine. So, the British began converting one to use a Merlin, but North American heard about it and began designing a version in house to take the Merlin. The N.A. version was much better looking and performing. Once the pilots who had flown it finally convinced the USAAC it was the plane they needed to escort their bombers during their entire missions. The rest sctually is history.

Also, it should be noted that with regard to doctrine, the U.S. had developed high altitude fighters for escorting bombers. This allowed them to compete with Germans in that regard and gave them an advantage over the Japanese who lacked that capability for most of the war. Also, the P-51s speed conferred an advantage that is also a cornerstone of fighter combat; who ever has the speed, controls the fight. If you have the faster aircraft, you have the ability to choose to engage or disengage the fight. Neither of those are options for the slower aircraft.

Also, regarding aircraft design/technology and doctrine, the P-39 is a very good example of how the two are intertwined. The USAAC didn't like the P-39 because it could stall/spin at higher alpha (tight turns) with little to no warning, it didn't have much range due to it's engine location, and it didn't have turbo-superchargers, because those were reserved for the aircraft with higher performance. As a result, the P-39 was limited to low altitude, short range, combat. However, the Russians loved them because their doctrine dictated that the purpose of the air force wasn't so much to control the skies as it was to support the ground forces. So the battles on the Eastern Front were largely at low to medium altitudes. They also liked the P-39s maneuverability. They didn't like it's U.S. cannon, because it frequently jammed up, so it was replaced by a Russian 20mm IIRC?

Of course, sometimes doctrine and technology diverge due to unforeseen circumstances. One of the most advanced weapons systems developed during WW2 was the B-29. It was designed to bomb from very high altitudes while the crew sat in relative comfort in a pressurized fuselage, while carrying a large bomb load a very long distance and used turrets that had lead computing computers to aim their turrets. It was a wonder of technology that was largely negated by winds aloft over Japan. The trade winds are so strong over Japan and in varying directions at different altitudes that the B-29s couldn't hit their targets from high altitude over Japan. So instead of flying above most of the threats, they ended up at 10,000 feet scrapping with everything Japan could throw at them.

Lastly, one of the most important developments of WW2 wasn't just jet engines; it was guided weapons. The Germans were working on A2G weapons like the Frtiz-X, while the U.S. had the Northrop BAT and the Azon. Also the German work on their early A2A rockets and of course, the V-1 and V-2. And lastly, the development of Atomic weapons, which would change the face of warfare forever.

 

[robunos]

the object isn't to reverse direction, it's to break port or starboard as fast and as hard as you can, _while maintaining a radar track on the other guy_. Which limits you to a bit more than a ninety degree turn, depending on how far to the side you can turn your radar antenna. That radar track is essential because you have to keep illuminating the other guy if you're using a semi-active missile like AIM-7 or Skyflash, or because you need to keep updating the inertial phase of AIM-120 or Meteor.

Would it be feasible to equip the aircraft with distributed, conformal antennas, in order to generate these signals without having to use the main radar ?

cheers,
Robin.

 

[Basher54321]

You are talking about the reconstructed LWF requirements chart in Herb Hutchinson's book, right? I presume he didn't have access to the original and reconstructed it from other documents. I'm not completely convinced that line was actually in the final LWF request document, though you'd need a copy to settle it for sure.

I have a copy of one of the actual LWF responses in front of me, and it describes a range-only radar fit, while suggesting for the prototype to not even bother with that, just a beacon interrogator / transponder system for gunnery trials. There is no mention anywhere of capability to fit all-weather equipment, which seems a strange omission to make if it was a requirement. The YF-16 nose was too small to fit a useful radar, and Boeing's design was even worse, very thin "needle" nose.

That is right - I contacted him to clarify some of the things he had written about regarding the LWF and John Boyd in particular. Needless to say he thinks he is right but as ever.......

I will probably be digging for some time regarding things like nose size. On the one hand it was a tech demonstrator with no radar type or antenna size specified. On the other hand the XF4H-1 also started with a tiny radome and the F-4 needed a nose job early into production.


This is interesting - will have to find where it was from.

Although the LWF requirement specified only minimal electronics , the design team recognized that an operational aircraft would probably require a heavier and more bulky avionics package. The decision was made to size the aircraft to carry heat-seeking Sidewinder missiles plus an M61 cannon, but to make provisions to allow Sparrow radar-homing missiles to be carried at a later date should this be required.

F-16.net - The ultimate F-16, F-35 and F-22 reference

www.f-16.net

 

[DWG]

the object isn't to reverse direction, it's to break port or starboard as fast and as hard as you can, _while maintaining a radar track on the other guy_. Which limits you to a bit more than a ninety degree turn, depending on how far to the side you can turn your radar antenna. That radar track is essential because you have to keep illuminating the other guy if you're using a semi-active missile like AIM-7 or Skyflash, or because you need to keep updating the inertial phase of AIM-120 or Meteor.

Would it be feasible to equip the aircraft with distributed, conformal antennas, in order to generate these signals without having to use the main radar ?

Yes, but given the need to maintain a track on the target, not just maintain the datalink, you're effectively talking about a 360 degree radar fit.

 

[DWG]

The U.S. didn't want it, because they had the P-47 and the P-38 and they were leery of a plane designed by the son of German emigres.

Not much I disagree with here, but I'm surprised by this point given Republic, by comparison, was founded/run by a bunch of Russian (Georgian) emigres (de Seversky*, Kartveli**, Gregor/Grigorashvili***) and how leery the US was of anything even potentially Bolshevik linked, a suspicion that would only be amplified by the 1939-41 Molotov-Ribbentrop Pact and doubly so with de Seversky's sale of the Seversky 2PA-B3 / A8V1 escort fighter to the IJNAAF.

* Ousted from the company later 1939, but still the man who built it up, and the P-47's design starts in the Seversky era
** Absolutely fundamental to the P-47
*** Gone by this point (I think) and I'm unclear how significant he was at Seversky/Republic, but clearly a capable designer

 

[robunos]

Yes, but given the need to maintain a track on the target, not just maintain the datalink, you're effectively talking about a 360 degree radar fit.

Basically, yes, a sort of 'Radar EODAS' system. With further thought, there wouldn't be enough power for an illumination beam, but providing the datalink signal should be OK, but some fancy computer systems will be needed, to hand-off the signal to the appropriate antenna, as the aircraft manoeuvres . . .

cheers,
Robin.

 

[Sundog]

The U.S. didn't want it, because they had the P-47 and the P-38 and they were leery of a plane designed by the son of German emigres.

Not much I disagree with here, but I'm surprised by this point given Republic, by comparison, was founded/run by a bunch of Russian (Georgian) emigres (de Seversky*, Kartveli**, Gregor/Grigorashvili***) and how leery the US was of anything even potentially Bolshevik linked, a suspicion that would only be amplified by the 1939-41 Molotov-Ribbentrop Pact and doubly so with de Seversky's sale of the Seversky 2PA-B3 / A8V1 escort fighter to the IJNAAF.

* Ousted from the company later 1939, but still the man who built it up, and the P-47's design starts in the Seversky era
** Absolutely fundamental to the P-47
*** Gone by this point (I think) and I'm unclear how significant he was at Seversky/Republic, but clearly a capable designer

It's because we were at war with the Germans and the Russians were one of our allies. Also, there were U.S. citizens who left the country and went to fight for the Germans. It's talked about in this book, P-51 Development of the Long Range Escort Fighter. The thing is, I agree with you and especially from the stand point that his family emigrated here when he was a child. But hell, we put Japanese Americans in camps in WW2, so is it really surprising?

 

[DWG]

The U.S. didn't want it, because they had the P-47 and the P-38 and they were leery of a plane designed by the son of German emigres.

Not much I disagree with here, but I'm surprised by this point given Republic, by comparison, was founded/run by a bunch of Russian (Georgian) emigres (de Seversky*, Kartveli**, Gregor/Grigorashvili***) and how leery the US was of anything even potentially Bolshevik linked, a suspicion that would only be amplified by the 1939-41 Molotov-Ribbentrop Pact and doubly so with de Seversky's sale of the Seversky 2PA-B3 / A8V1 escort fighter to the IJNAAF.

* Ousted from the company later 1939, but still the man who built it up, and the P-47's design starts in the Seversky era
** Absolutely fundamental to the P-47
*** Gone by this point (I think) and I'm unclear how significant he was at Seversky/Republic, but clearly a capable designer

It's because we were at war with the Germans and the Russians were one of our allies.

It's pretty clear all the critical decisions were made during the period when the US was at peace with Germany and Russia was a German ally.

23 Aug 1939 Russia signs Molotov-Ribbentrop Pact, becomes German ally
17 Sep 1939 Russia joins the German invasion of Poland
Nov 1939 Russia invades Finland
Nov 1939 USAAC backs Republic proposal as XP-47
Jan 1940 NAA start discussing design of the NA-73 Mustang with the British Purchasing Commission
4 May 1940 NAA given go-ahead for the NA-73 Mustang by the British Purchasing Commission
29 May 1940 British Purchasing Commission order 320 NA-73 Mustang Mk1s under Cash and Carry
12 Jun 1940 Kartveli submits revised XP-47 to USAAC
15 Jun 1940 Russia invades Latvia, Lithuania, Estonia
7 July 1940 USAAC orders 150 P-51s (NA-91/Mustang Mk 1A) for the UK under Lend-Lease
13 Sep 1940 USAAC backs revised Republic proposal as XP-47B, orders 200 P-47Bs.
26 Oct 1940 NA73 Mustang first flight
22 Jun 1941 Germany invades Russia, Russia ceases to be German ally
24 Aug 1941 First of two Mustangs arrive at Wright Field for USAAF assessment
11 Dec 1941 Germany declares war on US
Dec 1941? USAAF retains 57 P-51s from the Lend-Lease order due to the outbreak of war
16 April 1942 USAAF orders A-36 Apache, first non-Lend-Lease USAAC order for the Mustang.

 

[BB1984]

the object isn't to reverse direction, it's to break port or starboard as fast and as hard as you can, _while maintaining a radar track on the other guy_. Which limits you to a bit more than a ninety degree turn, depending on how far to the side you can turn your radar antenna. That radar track is essential because you have to keep illuminating the other guy if you're using a semi-active missile like AIM-7 or Skyflash, or because you need to keep updating the inertial phase of AIM-120 or Meteor.

Would it be feasible to equip the aircraft with distributed, conformal antennas, in order to generate these signals without having to use the main radar ?

Yes, but given the need to maintain a track on the target, not just maintain the datalink, you're effectively talking about a 360 degree radar fit.

Couple quick points:

• "break port or starboard as fast and as hard as you can" is instantaneous turn rate / corner speed, not sustained turn
  
  
• AESA radars typically have about a 60 degree left / right capability, using a fixed plate
  • The "field of view" limitation for the F-22 AESA is significant enough that the plane was originally designed with additional "side looking" radar arrays, which were deleted from production for cost reasons
  • CAPTOR-E is promised to do 90 degrees by being able to mechanically point the radar a little to the side, but at the cost of greater mechanical complication, so presumably increased costs, both up front and for maintenance
  • Both these raise the issue of cost: it's not just what you could design into an airplane, it's also what you can afford to buy and maintain
    
    
• In the modern data link era, it can be misleading to focus too much on the radar capability / angles of a single plane. For data link equipped fighters, especially the stealthy ones with LPI AESA radars, one plane flying slower and at greater range, could do the target tracking for closer, faster moving "shooter" aircraft. Countries with AWACS support could run entire engagements without fighters using their own radars.

 

[Sundog]

I

It's because we were at war with the Germans and the Russians were one of our allies.

It's pretty clear all the critical decisions were made during the period when the US was at peace with Germany and Russia was a German ally.

The U.S. didn't want it, because they had the P-47 and the P-38 and they were leery of a plane designed by the son of German emigres.

Not much I disagree with here, but I'm surprised by this point given Republic, by comparison, was founded/run by a bunch of Russian (Georgian) emigres (de Seversky*, Kartveli**, Gregor/Grigorashvili***) and how leery the US was of anything even potentially Bolshevik linked, a suspicion that would only be amplified by the 1939-41 Molotov-Ribbentrop Pact and doubly so with de Seversky's sale of the Seversky 2PA-B3 / A8V1 escort fighter to the IJNAAF.

* Ousted from the company later 1939, but still the man who built it up, and the P-47's design starts in the Seversky era
** Absolutely fundamental to the P-47
*** Gone by this point (I think) and I'm unclear how significant he was at Seversky/Republic, but clearly a capable designer

It's because we were at war with the Germans and the Russians were one of our allies.

It's pretty clear all the critical decisions were made during the period when the US was at peace with Germany and Russia was a German ally.

Read the book I listed, I can only tell you what they reported about the head of material command at the time.

 

[HoHun]

Hi,

In World War I, the primary/ priority attribute of fighter is turn rate, better turn rate make better fighters
In World war II, fighters with better speed and acceleration are better. In short, "boom and zoom" are better than "turn and burn". Turn rate are not important Ex: P-51, P-47
In the 1960-1970s, the priority become top speed, acceleration, BVR Ex: F-4
In the 1980-1990s, there is emphasize again on Sustained turn rate, Instantaneous turn rate. Ex: F-16
so what make turn rate important again in the 1980-1990s ? why zoom and boom tactic no longer effective?

I would like to suggest that in WW1, turn rate actually wasn't as important as it is in popular perception. I'd say the most important main fighter types near the end of the war were the Fokker D.VII, the SE5a, the Spad XIII and the Sopwith Camel. Of these, the first three were really built for performance primarily, and while it could be argued that the Sopwith Camel surpassed the others in manoeuvrability, by the end of war, it seems to have been used mostly for ground attack missions.

Accordingly, the priority of fighter attributes might have seen a preference of speed over other attributes pretty much since the beginning, and only become less important after fighters were able to reach Mach 2. The highest speed of relevance for fighter-vs.-fighter combat might actually have been a bit lower than that, and when interception of nuclear bombers became less important since ICBMs became the main nuclear threat, it was possible to give other characteristics piority instead.

Of course, much of this has already been pointed out by others above, but I believe that with the different perspective at WW1 priorities, the emphasis overall really had been a steady desire to increase top speeds until the region of rapidly dimishingly returns was reached, with a temporary venture into that region owed to the priority of bomber interception over fighter-vs.-fighter combat.

At least, that's the picture I painted for myself ;-)

Regards,

Henning (HoHun)

 

[Vanessa1402]

The later F-15/F-16 programs were a "have your cake and eat it too" solution where advanced engines and aerodynamics allowed planes to have both excellent horizontal and vertical maneuverability. They were both conceived and designed before all aspect and off-boresight AAM were in production and before BVR missile technology had demonstrated serious combat potential, i.e., when energy maneuver was still the best approach. .

So in conclusion, with agile WVR missile then turn rate are more important, with cannon only then acceleration are more important?

I think it's more complicated overall, though you can make some general statements like "As WVR missiles become more capable and all aspect, the important thing becomes how fast you can get the nose of the aircraft pointed in the right direction to fire the missile, and, with off boresight missiles becoming more prevalent, even that is becoming less important."

This is a summary chart from a blog post from Elements of Power; the whole article is worth a look and is here. AA refers to "All Aspect", i.e., it can be fired at a plane from any angle, not just from behind.

View attachment 665698

that chart still can't answer the question of what more important in WVR combat: the acceleration or the turn rate.
Some fighters are more focus on acceleration: English Electric lightning, F-16, F-15, Mig-29
some fighters are more focus on turn rate: F-18, Su-27, F-14

 

[BB1984]

that chart still can't answer the question of what more important in WVR combat: the acceleration or the turn rate.
Some fighters are more focus on acceleration: English Electric lightning, F-16, F-15, Mig-29
some fighters are more focus on turn rate: F-18, Su-27, F-14

I believe what the chart is saying is that acceleration and turning are both very important, equally so, but what kind of turn rate is important changed:

• before all aspect missiles, acceleration and sustained turn rate were both very important, which is consistent with historical dogfighting results
• after all aspect missiles, acceleration remained very important but sustained turn rate became much less important. While sustained turn became much less important, instantaneous turn rate / corner speed became much more important, equally important to acceleration.

I'm not saying that the chart is definitive, no chart could be given the variables in air to air combat, but the history of WVR seems supportive.

IMHO, up through Korea, and arguably a generation of planes afterwards, acceleration was often associated with speed and height advantages which gave one plane the initiative, which was very valuable for choosing both when to engage in WVR and when to get out of WVR. Then, as the planes max speeds became much greater than their fighting speeds, this advantage disappeared.

Arguably it has reappeared in a different form with super cruise, which can confer a practical speed advantage even between planes with similar max speed.

 

[uk 75]

Lightnings were designed to shadow or shoot down Soviet bombers. Hence acceleration rather than turn rate.

 

[riggerrob]

Many modern fighters: F-15, F-16, F-18, F-22, F-35, Grippen, etc. can only fly Mach 1.8 because they found that most fighting is done slower than that. BVR missiles reduce the need for airplanes to perform spectacularly. The other factor is that Mach 1.8 allows for simple, fixed engine intakes, while faster requires more complex variable intakes: F-14, etc.

 

[uk 75]

Ever since their use in Vietnam there has been speculation that RPVs UAVs will take over from fighters with pilots.
While drones regularly plink our enemies in far off places we have not found it necessary to do the same to them in the air.
If anyone does do it, my money is on the Israelis. They are in a region with lots of enemy air forces and they value the lives of their own people. Avoiding IDF pilots falling into the clutches of Syria or Iran is probably worth developing UAVs.

 

[T. A. Gardner]

In World War I, the primary/ priority attribute of fighter is turn rate, better turn rate make better fighters
In World war II, fighters with better speed and acceleration are better. In short, "boom and zoom" are better than "turn and burn". Turn rate are not important Ex: P-51, P-47
In the 1960-1970s, the priority become top speed, acceleration, BVR Ex: F-4
In the 1980-1990s, there is emphasize again on Sustained turn rate, Instantaneous turn rate. Ex: F-16
so what make turn rate important again in the 1980-1990s ? why zoom and boom tactic no longer effective?

What changed is really the wrong question to ask. It's far more a matter of "What's possible with the extant technology?"

From WW 1 to today, what we've seen as the top improvement in combat aircraft is they have gotten more and more power in lighter and lighter formats. That is, the power to weight ratio has improved dramatically. In roughly a century aircraft powerplants have gone from around 100 HP to well in excess of 10,000 HP.

Turn rate is effectively limited by the amount of G's the pilot can withstand. So that's capped even if the aircraft can take far more.

Energy has always been a big issue with aircraft. With more excess energy, climb rates are better and sustained climbs can be made at steeper angles for longer periods of time. Weight and aerodynamics come next in this and a better design will retain more energy after a maneuver than one with higher drag and weight.

To the question asked, what made turn rates, and energy maneuvering top the list was the realization that in actual combat situations aircraft were going to be required more often than not, to close to visual range to confirm their target was actually an enemy aircraft. Shooting missiles off radar alone was not going to be the norm.

Thus, aircraft went from being long range missile armed interceptors back to being energy maneuvering fighter aircraft.

 

[CV12Hornet]

Many modern fighters: F-15, F-16, F-18, F-22, F-35, Grippen, etc. can only fly Mach 1.8 because they found that most fighting is done slower than that. BVR missiles reduce the need for airplanes to perform spectacularly. The other factor is that Mach 1.8 allows for simple, fixed engine intakes, while faster requires more complex variable intakes: F-14, etc.

Um, the F-15 has a top speed of Mach 2.5 and the F-22 can crack Mach 2 itself, though the precise top speed is heavily classified.

 

[Sundog]

Many modern fighters: F-15, F-16, F-18, F-22, F-35, Grippen, etc. can only fly Mach 1.8 because they found that most fighting is done slower than that. BVR missiles reduce the need for airplanes to perform spectacularly. The other factor is that Mach 1.8 allows for simple, fixed engine intakes, while faster requires more complex variable intakes: F-14, etc.

The Mach 1.8 limit of many of the light weight fighters was basically a result of minimizing cost while maximizing performance. You could use composites up to that point without having any heating problems and use fixed inlets to reduce weight and complexity, and hence, cost.