Fighter: Flop or Not

[K5083]

Post-war the USAF didn't order any attack-designated aircraft, did it? The first in the tri-service system is the A-9. A-10 is the only one they have ordered post-WW2.

RR Nene had plenty of thrust and TBO. The supposed advantage of axial over centrifugal took a long time to materialize in the operational world.

And it is useless to compare aircraft from a time of such rapid technological change from seventy years ago, where a couple of months covers so many developments and what was going on elsewhere was secret.

 

[Fighterguy]

Another thing to consider, the political climate within USAF leadership at the time. This was the era (more like error) of the "Bomber Boys," flush with success from WWII's strategic bombing campaign, along with a new bomb that wrecked entire cities, they relegated fighters to bomber intercept and ground attack. Being able to out-maneuver an opponent in aerial combat was not part of the equation. Commanders were routinely cautioned not to even discuss "dogfighting." Missiles, as the new dogma dictated, would remove the need for aerial combat training.

 

[Fighterguy]

Post-war the USAF didn't order any attack-designated aircraft, did it? The first in the tri-service system is the A-9. A-10 is the only one they have ordered post-WW2.

RR Nene had plenty of thrust and TBO. The supposed advantage of axial over centrifugal took a long time to materialize in the operational world.

And it is useless to compare aircraft from a time of such rapid technological change from seventy years ago, where a couple of months covers so many developments and what was going on elsewhere was secret.

Jets, because of their higher attack speeds, weren't as successful at ground attack as their piston forebears such as the A-1 Skyraider or Hawker Tempest, capable of carrying a large array of ordinance, good loiter, and exceptional maneuverability. The A-10 came later when the U.S. Army was considering an attack helicopter (AH-56 Cheyenne) that the Air Force saw as a threat to keeping the CAS role. Here, Pierre Sprey used input from A-1 Skyraider pilots and ground commanders to develop the initial design requirements for what became the A-10.

 

[Zipper730]

F4U Corsairs could use their landing gear as dive brakes, there was a selector in the landing gear controls that allowed the selection of main gear only. leaving the tail wheel retracted.

So I guess if they can keep them down safely to a high enough air-speed, you're good to go.

The Army tried using single engine Navy dive bombers early in WW II but lost interest real quick. A big problem was range.

Which the Navy had less trouble with because they could move the base into position to attack their target.

Obviously long range was desired for new designs which often meant at least some sort of Bomb-bay even if only for part of the load.

1. How much range was needed to operate over the Pacific in conditions from 1942-1943?
2. Regarding bomb-load: Were they still using 30 pound fragmentation bombs for antipersonnel use or larger stuff?

Post war with the introduction of jets there were several problems. One was the above mentioned stalling of development for several years. Jet engine gave unmatched performance but they had around 1/10 the overhaul life of a good piston engine. Something happened ( or a number of somethings) and the performance and engine life uncorked around 1950 and all the promise of the jet engine came in with a rush after 4-5 years of slow progress.

What caused the delay? A matter of simple technological progression, funding shrinking post war, or both?

As far as fighter vs fighter goes in Korea, once the Mig 15 showed up, every straight wing fighter was demoted to a distant 2nd place.

That I'm well aware of, but when it comes to other fighters of the era (and I feel like I'm repeating myself), it didn't perform very good.

While I'm unsure how the Meteor F.4 through F.8 and the Vampire designs from 1946-1950 performed relative to the early F-80 and F-84, and

just about every USAAC attack aircraft in the 1930s had four .30 cal guns for strafing

Which reflects the desire for strafing-planes.

The A-20s, as they left the factory, rarely had more than four .30 cal guns until the first "G" models in Feb 1943.

Of course, but those were very large aircraft

Post-war the USAF didn't order any attack-designated aircraft, did it? The first in the tri-service system is the A-9. A-10 is the only one they have ordered post-WW2.

First of all, the last attack designations that the USAAF had was A-45 if I recall.

Secondly, the tri-service system doesn't start with A-9: Here's the listing from A-1 to AV-8

• A-1: AD Skyraider
• A-2: AJ Savage
• A-3: A3D Skyrwarror
• A-4: A4D Skyhawk
• A-5: A3J Vigilante
• A-6: A2F Intruder
• A-7: A-7 Corsair II (possibly the first to have the new designation scheme off the bat)
• AV-8: Harrier

McNamara dictated the US Navy and Marine Corps adopt a system similar to the US Air Force because he found the USAF system easier to wrap his mind around. He created a committee of several officers from the USAF, USN/USMC, maybe a few army guys, and told them to set-up a new system.

The rules were as follows

• Aircraft currently under development within the USAF that have received a designation keep their designation
• Cargo planes within the USAF currently in development as well as numbers that go up to 142 (no idea why), keep their designation
  
• Everything else goes back to 1 with the USN planes redesignated into that category
• Everything after that is where all new designs start off from (except cargo planes up to 142)

The USN/USMC wanted the attack designation to remain: I'm not 100% sure why, but it's possible any of the following were possible

• The USN already used the term "Attack" and didn't feel like catering to the USAF terminology unless their careers or lives were threatened
  
• The term "Attack" is more versatile than "Bomber": Bombers attack with bombs; Attack planes attack with guns, rockets, bombs, missiles, and a kitchen sink if there's one lying around.
• The USN was worried that the USAF would begin to dictate terms of what constitutes a light-bomber to the point that the USN could never hope to operate any off a carrier deck.

And it is useless to compare aircraft from a time of such rapid technological change from seventy years ago, where a couple of months covers so many developments and what was going on elsewhere was secret.

Well, if you're evaluating excellent designs, average designs, substandard designs, or flops, you can compare from everywhere.

Another thing to consider, the political climate within USAF leadership at the time. This was the era (more like error) of the "Bomber Boys," flush with success from WWII's strategic bombing campaign, along with a new bomb that wrecked entire cities, they relegated fighters to bomber intercept and ground attack.

You make very good points, but I want to point out the following

• The USAAF in it's last days, and the USAF in it's very early days were still interested in the idea of bomber-escort: This attitude would change with the B-47, but even into the early 1950's there would be projects like Tip-Tow for the older propeller driven aircraft designs
  
• Most people think the F-86 interestingly was designed to be an interceptor: It actually was designed to be a medium-ranged day-fighter that could escort bombers with drop-tanks, and be an effective fighter-bomber. It turned out to be a remarkable fighter (it was a good fighter-bomber too), though it's escort capability probably could have been better (though it did work to a point).
  
• The USAAF had several attack and light-bomber designs flying after the war-ended: The XB-42, XA-43, XA-44, XA-45, and XB-43; With the exception of the XB-42 and XB-43, the others were conceived around 1945. The XA-44 and XA-45 would be given bomber designations (XB-53 and XB-51), the XB-42, XB-43, and XB-51 would fly: The XB-42 would fly during the war (1944) as a prototype (it would remain flying until 1947), the XB-43 (a jet-powered B-42) and XB-51 would fly in the post-war era.
  
• The A-26 Invader would be re-designated as the B-26 and would remain flying through the Korean war.

Being able to out-maneuver an opponent in aerial combat was not part of the equation.

From 1945-1953, far as I know that was still considered highly important. Missiles seemed to appear on the scene in 1954, and that did have a strong effect on the face of aerial combat. The USAF did categorize fighters into several categories, and interceptors usually didn't carry guns; most others did however.

Commanders were routinely cautioned not to even discuss "dogfighting." Missiles, as the new dogma dictated, would remove the need for aerial combat training.

When was this?

Jets, because of their higher attack speeds, weren't as successful at ground attack as their piston forebears such as the A-1

Yup, turning circle, and endurance with payload are key.

The A-10 came later when the U.S. Army was considering an attack helicopter (AH-56 Cheyenne) that the Air Force saw as a threat to keeping the CAS role.

Which is funny because they didn't even want it -- they just didn't want the Army to have it.

Pierre Sprey used input from A-1 Skyraider pilots and ground commanders to develop the initial design requirements for what became the A-10.

Sprey actually did a good job on this, but Sprey had a tendency to risk terminological inexactitude at times.

 

[davparlr]

-- it could have used more agility and a lot less weight.

a statement applicable to every fighter. Ruggedness often implies increased weight and the F-84 was rugged. It was indeed heavier than the F-80, slightly heavier than the F9F, equal to the F-86A, and much lighter than the F2H. I'm not sure weight was unreasonable.

But not at the beginning -- the F-84 wasn't that good at the beginning.

The F-84E, the plane sent to Korea, seems to have had most of the bugs worked out. Main problem seems to have been shortages of parts, especially the J-35 engine. This seems to have been caused by underestimating the F-84 utilization rate which affected spare procurement.

But how'd it compare in turning performance?

Turning performance does not a great fighter make. Many a great turning aircraft failed to live up to mission requirements. The F-4 was not a great dog fighter, I heard one F-4 pilot even called it a dog, indeed, it was not great at anything (except top speed). However it was good at many things to such an extent that it is just about on every ones list of great fighters. The F-84 was no worse an air to air fighter than all the straight wing jets of the day but it was a superb air to ground fighter and did great service in this role, thus not a flop.

 

[Graeme]

. Ruggedness often implies increased weight and the F-84 was rugged.

Absolutely...

 

[Graeme]

..

What did Winkle Brown think of both?

Dunno. But I did find one he did on the Panther - not overly impressed with it. But all the jets of the era were basically under-powered...

 

[Graeme]

Obviously the F-84E could get outta trouble..

 

[XBe02Drvr]

What caused the delay? A matter of simple technological progression, funding shrinking post war, or both?

The technology was brand new and brought with it many frontiers with steep learning curves: compressor efficiency, turbine efficiency, combustion efficiency, high temperature metallurgy, lubrication, cooling, fuel metering management, etc. All the "rule of thumb" solutions that had evolved in advanced recip engines were of only limited applicability in these new blowtorches. A lot of engineering parameters that designers based their work on had to be recalculated again and again. Remember, in those days it was all laborious slide rule work, no Cray supercomputers to lean on.
Zipper stated the F-84 could have used a little more agility and a lot less weight. No. What it really needed was more thrust. The weight was necessary for ruggedness, and the reduced energy bleed in maneuvering due to more thrust would have helped out with the agility issue. Here's a dream to chew on; how about an F-84 with an afterburning RR Spey?
Cheers,
Wes

 

[Shortround6]

So I guess if they can keep them down safely to a high enough air-speed, you're good to go.

The F4U didn't have any trouble keeping the dive brake/main gear down. Restrictions in the pilot's manual are not to exceed 200kts for the landing gear due to damaging the tail wheel doors. No lowering of the dive brakes at over 260kts as the hydraulics won't fully lower the gear and finally no retracting the dive brakes at over 350kts (402mph). Plese note that these are indicated airspeeds.

Which the Navy had less trouble with because they could move the base into position to attack their target.

That and bigger long range planes wouldn't fit/fly on carriers.

2. Regarding bomb-load: Were they still using 30 pound fragmentation bombs for antipersonnel use or larger stuff?

usually larger (like 100lb bombs, minimum) the small bombs had been fitted into chutes in the top of the bomb bay.

The iconic holes in the rear of the cockpit cover are actually the very top of the chutes/tubes. With the tubes taken out and using horizontal bomb stowage room was found for up to 325 gallons of fuel in the upper part of the bombay, extending range considerably.

What caused the delay? A matter of simple technological progression, funding shrinking post war, or both?

This has been answered by another board member, funding was only severely cut for end of 1945 and 1946,

That I'm well aware of, but when it comes to other fighters of the era (and I feel like I'm repeating myself), it didn't perform very good.

Some of us feel like we are repeating ourselves also. Progress was so fast from 1946 on that a two year difference was almost a different era. As an example work started on a supersonic version of the Sabre (first flown in Oct 1947) in Feb 1949. This required not only a new (or heavily modified) airframe but new engines of much greater power. It lead eventually (two re-starts) to the F-100 which first flew in April of 1953 using an engine almost four times as powerful as the ones used in the early F-84s. In fact the preliminary studies back in 1949 had called for engines of at least double the power of the engines going into production F-84s. Yes this is extreme but you have to know what was going on behind the scenes too.
The F2H-1 used a pair of 3000lbs thrust engines, the F2H-2 used 3250lb thrust engines, Please note that the 6000fpm climb given in wiki for a F2H-3 was achieved using less than full internal fuel, a lot less than full.
The F9F Panther also needs a closer look. 1, it's P & W J 42 engine was about 700lbs lighter than the J-35 used in the F-84. 2, it made about 5000lbs thrust to start with instead of 3750lbs and at some point it went to just under 6000lbs with water injection. Later F9Fs got P & W J 48 engines with 7000lbs of thrust wet. and 6250lbs dry 3. while a late model F-9F could climb at 6000fpm at sea level it required no only a 6250lb thrust engine, it required a weight of 15,389lbs which was achieved by not only leaving the wing tip tanks empty but by leaving out over 20% of the normal internal fuel. Panther first flew 20 months after the F-84.

While I'm unsure how the Meteor F.4 through F.8 and the Vampire designs from 1946-1950 performed relative to the early F-80 and F-84, and

Not really that hard to find. And please consider that the Derwent 5 used in the Meteor gave 3600lbs thrust each but weighed only 1250lbs. just over 1/2 what a J-35 weighed.

Which reflects the desire for strafing-planes.

The attack planes (from the Curtiss Shrike on) not only carried double the number of guns as a "fighter" although none of the early attack planes ever swapped a .30 cal for a .50cal like the fighters could do they also often carried double the bomb load.
The Curtiss A-12 for example

Not only carried the four .30 cal guns but could carry twenty 30lb fragmentation bombs inside or four 112lb bombs outside. Which is not too shabby for 1933/34. Since a .30 cal gun only weighs about 25lbs and 500 round of .30cal ammo goes about another 30lbs cutting back on the guns doesn't really do much for the bomb load or overall size of the airplane.
I would also note that German aircraft did quite a bit of strafing in both Poland and the French Campaigns. Not quite as headline grabbing (or news reel worthy) as dive bombing but caused a large amount of disruption on supply and evacuation routes for a limited weight of ordnance expended.

 

[Shortround6]

What it really needed was more thrust. The weight was necessary for ruggedness, and the reduced energy bleed in maneuvering due to more thrust would have helped out with the agility issue. Here's a dream to chew on; how about an F-84 with an afterburning RR Spey?
Cheers,
Wes

The heck with that, how about an Orpheus engine from a Jaguar?
even without the after burner. 5000lbs of thrust while 1600lbs lighter

 

[XBe02Drvr]

Pedal to the metal, man!

 

[Zipper730]

a statement applicable to every fighter.

Probably true! But there is definitely such a thing as too little, and that's honestly way more dangerous...

Ruggedness often implies increased weight and the F-84 was rugged. It was indeed heavier than the F-80, slightly heavier than the F9F, equal to the F-86A, and much lighter than the F2H. I'm not sure weight was unreasonable.

1. How rugged was the F-80 compared to the F-84?

2. The F2H and F9F were carrier based airplanes, both had more overall thrust than the F-84.
3. The F-86 had more thrust than the F-84 and a bigger wing

Turning performance does not a great fighter make.

But the ability to turn & climb well are extremely useful

The F-4 was not a great dog fighter, I heard one F-4 pilot even called it a dog, indeed, it was not great at anything (except top speed).

It could accelerate and climb quite well, as for turning performance: It was bad under most situations owing to a high corner-velocity. It could sustain 7g under those conditions however.

it was a superb air to ground fighter and did great service in this role

Just to be clear, I'm not disputing it's ability to move mud. I'm just pointing out that it could have been a way better fighter.

Obviously the F-84E could get outta trouble..

So, at low altitudes it could turn tighter than the MiG-15? Was this due to the heavier control forces or something else?

The technology was brand new and brought with it many frontiers with steep learning curves: compressor efficiency, turbine efficiency, combustion efficiency, high temperature metallurgy, lubrication, cooling, fuel metering management, etc. All the "rule of thumb" solutions that had evolved in advanced recip engines were of only limited applicability in these new blowtorches. A lot of engineering parameters that designers based their work on had to be recalculated again and again.

Honestly, I would not have envisioned lubrication as a major problem compared to pistons. Combustion efficiency, engine cooling, higher pressure-ratios seem to be something that would make sense, the effective of higher pressure ratios on turbines also makes sense as well. Scaling probably also makes sense.

Zipper stated the F-84 could have used a little more agility and a lot less weight. No. What it really needed was more thrust.

It could have used both truthfully...

The weight was necessary for ruggedness

The MiG-15 was pretty rugged, though it wasn't that heavy...

 

[XBe02Drvr]

Honestly, I would not have envisioned lubrication as a major problem compared to pistons. Combustion efficiency, engine cooling, higher pressure-ratios seem to be something that would make sense, the effective of higher pressure ratios on turbines also makes sense as well. Scaling probably also makes sense.

Lubrication, like combustion efficiency, fuel metering, high temp metallurgy, turbine and compressor performance, were all technologies very highly refined for the demands of high horsepower reciprocating engines. The jet engine was a whole different animal.
Take lubrication for example. The main function of lubrication in a recip is to to provide a viscous durable film between metal surfaces sliding against each other, such as piston rings and cylinder walls or cam lobes and cam followers or crankshaft journals and sleeve bearings. In a jet there's almost none of this sliding. The engine spool rides on roller bearings and spins at more than 10 times the RPM of a recip. The temperature range is greater than a recip and the lubricant must maintain nearly constant viscosity from -40C to 900+. A jet can't idle at 800 RPM after a subzero start while sludge-like mineral oil warms up and thins out. A typical jet idles at 60 - 65% of its full power setting of 35 - 40K RPM. It requires a high grade of synthetic oil.
So even though lubrication was highly developed for the the recip application, it required a whole new technology when it came to jets. The same goes for fuel metering. And metallurgy. And compressor and turbine performance. (Early turbocharger technology from whence the early jets came, was nowhere near efficient enough to provide useful thrust.)
Another major learning curve was designing durable efficient burner cans, yet another brand-new technology.
As mentioned earlier in this thread, a convergence of these learning curves resulted in a quantum leap in thrust output in the early 50s in the US. The Brits and the Soviets were a couple years ahead of us on this.
Cheers,
Wes

 

[Shortround6]

2. The F2H and F9F were carrier based airplanes, both had more overall thrust than the F-84.
3. The F-86 had more thrust than the F-84 and a bigger wing

We need to quite arguing in the dark (no facts) and bring some light on the subject (facts).

Plane................wing area..............thrust...............empty weight...........combat weight.......L/F.......internal fuel
F-84B.................260sq ft.............3750lbs...................9538lb.......................13,465lbs...............7.33........416 gal
F2H-2.................294sq ft...........2 x 3250lbs...........11146lbs......................15,640lbs...............6.4.........877 gal *
F9F-5................. 250sq ft.............6250lbs................10147lbs......................15,359lbs.............7.25.......763 gal*
F-86F..................294sq ft..............5910lbs...............10850lbs......................14,857lbs..............7.33........435 gal
F-84E-25...........260sq ft..............4900lbs...............10300lbs.......................14,775lbs.............7.33........452 ga

These numbers are from the "standard aircraft characteristics" data sheets I could find but they need a few notes.
1, the planes listed did not enter service at the same time, there is about a 4 year spread. The F-84B went OUT of production in June of 1948, the E went into production in May 1949. The F-86F didn't go into production until April of 1952. The F2H-2 didn't go into production until Aug of 1949 (end of production for the F2H-1). The F9F-5 went into production in Nov of 1950. The first service model was the F9F-2 which went into production in Aug 1949. A major difference was that they used a P & W J42 engine of 5000lbs thrust dry instead of the 6250lb J48 engine in the above chart. For the F-86 the first E wasn't delivered until Feb 1951, Early F-86As had problems with the engines and production was slowed/halted until the engine problems were straightened out. Second production batch of "A"s were the first to actually enter squadron service and production of this batch started in March of 1949. These aircraft used a 5340lb thrust engine.

as can be seen, comparing early jets is difficult as they changed fairly quickly and some of the changes were major.

2. The Navy planes are not not magic, they are NOT carrying full internal fuel at combat weights. At combat weight the F2H-2 is carrying about 526 gal of 115/145 gasoline for it's engines. The F9F-5 is carrying about 612 gals of 100/130 gasoline. The F-86F used JP-4 and the F-84B used either JP-1, JP-3 or 100/130.

Edit: The F-84G was in Production on June of 1951 with a 5600lb thrust J-35 engine, very few went to Korea. Most stayed state side or went to Europe so we have no (?) combat reports of F-84Gs in air to air combats. The F-84G was used as a long range escort for the SAC starting in 1952, mainly I suspect, because it was equipped for air to air refueling at the time and Sabre was not. Or the F-84 used the boom style refueling and the Sabre used probe and drogue?

 

[Elvis]

I'll start with the F-84 since who could possibly have an opinion about that one?

Personally, I'd say the F-84 was a flop for the following reasons

• The F-84 was an interceptor (though the initial origins of the F-84 was a jet-powered P-47, the idea was ultimately done away with because the centrifugal flow engines of the time would not fit in the P-47's fuselage): The primary role of interceptors is to shoot-down bombers (though the ability to shoot down fighters at the time was assumed), and this was achieved with a rapid rate of climb, a rapid acceleration, a high top speed and altitude, and heavy armament (i.e. cannon); while range is desirable if you can get away with it, it's not the overarching goal.
• The wings were thicker than were probably prudent due to the desire to carry a large load of fuel: This thickness caused problems at transonic speeds (most all wings did to some extent, but as a rule, thinner was better than thick)
  
• Problems with the strength of the air-frame lead to increase in weight that resulted in a heavier than ideal wing-loading: It could not turn with the F-80, nor could it climb as well due to the weight
• The design was almost cancelled because it could not meet any of the requirements for which it was originally built

The fact that it had long-range made it useful as a bomber-escort in theory, but in practice, it left a bit to be desired against the MiG-15 (While the F-86 was inferior in a number of areas to the MiG-15, the F-86 was superior in several areas too giving it the ability to balance itself out), and as a result the bombers found themselves used at night.

The air-to-ground capability was its saving grace, because of it's limited air-to-air capability. I should point out that the US Navy's F2H & F9F were both able to be used in air-to-ground missions, and were probably better designs overall (the F2H was also used as a nuclear strike plane, and it was more agile).

Interesting factoid. I had no idea it owed its lineage to the P-47.
One thing I did notice was that there were two YF-84J's built. These were F-84's retrofitted with J-73 engines.
Obviously, the idea didn't work (or maybe the notion was just considered not worth it on the aging airframe?), but I wonder how much of an impact that engine had on the plane's performance.
The J-73 was much more powerful than the J-35.


Elvis

 

[Shortround6]

The GE J73 was being used as a replacement for the Wright J-65 (Bristol Siddeley Sapphire) used in the swept wing F-84F.
The GE 73 was the engine used in the F-86H.

Stuffing one in an F-84 straight wing would be interesting. No doubt performance would be extraordinary. However the J-35s needed from 70-95lbs of air per second depending on model (3750lbs to 5600lbs thrust) . The J 47 engines in the F-86 needed a bit over 100lbs per second. the J-65 in the F-84F needed about 120lbs per second and the J 73 needed 150bs per second. Going to be one big intake for the J 73 engine
F-86H fuselage had a 6 in splice put in to deepen the fuselage/airducts.

 

[Zipper730]

We need to quite arguing in the dark (no facts) and bring some light on the subject (facts).

Plane................wing area..............thrust...............empty weight...........combat weight.......L/F.......internal fuel
F-84B.................260sq ft.............3750lbs...................9538lb.......................13,465lbs...............7.33........416 gal
F2H-2.................294sq ft...........2 x 3250lbs...........11146lbs......................15,640lbs...............6.4.........877 gal *
F9F-5................. 250sq ft.............6250lbs................10147lbs......................15,359lbs.............7.25.......763 gal*
F-86F..................294sq ft..............5910lbs...............10850lbs......................14,857lbs..............7.33........435 gal
F-84E-25...........260sq ft..............4900lbs...............10300lbs.......................14,775lbs.............7.33........452 ga

The F-84D/E and F9F-2 seem like they'd compare best with each other (not the F9F-5); the F2H-1 and F-84D/E would go better with each other.

comparing early jets is difficult as they changed fairly quickly and some of the changes were major.

True

2. The Navy planes are not not magic, they are NOT carrying full internal fuel at combat weights.

I thought as a general rule 50-60% fuel would be typical for combat missions, 80% for interceptions post war?

The F-84G was used as a long range escort for the SAC starting in 1952, mainly I suspect, because it was equipped for air to air refueling at the time and Sabre was not. Or the F-84 used the boom style refueling and the Sabre used probe and drogue?

I'm surprised the USAF cancelled the penetration fighter designs. Those would have been way better off than the F-84.

The GE J73 was being used as a replacement for the Wright J-65 (Bristol Siddeley Sapphire) used in the swept wing F-84F.
The GE 73 was the engine used in the F-86H.

It produced like 9200 lbf right?

 

[Shortround6]

The F-84D/E and F9F-2 seem like they'd compare best with each other (not the F9F-5); the F2H-1 and F-84D/E would go better with each other.

They would but I couldn't find SAC or CS sheets for those models. Many of these sheets can be found here : Standard Aircraft Characteristics Arcive

the one for the F-84E is: http://www.alternatewars.com/SAC/F-84E_Thunderjet_Block_25_and_30_SAC_-_18_July_1951.pdf

I think they are as close to "official" or primary source as you are going to get. They also have a lot of information and charts about different load conditions rather than the "snap shot" performance specifications in many websites books.
I figure that starting form a known position and trying to work backwards or forwards is better than starting from an uknown position.

I thought as a general rule 50-60% fuel would be typical for combat missions, 80% for interceptions post war?

This is not a good assumption, for wartime "intercept" missions most fighters would take-off with max internal fuel. Initial time to altitude (operational time) would be figured with full internal load minus warm up and take-off. Climb is also figured taking engine power time limits into account. Combat climb may be figured using combat power and a lower fuel load but that gets iffy as nobody really agreed on % if fuel left or tested climbs with partial fuel loads.
For escort missions the take off was made on internal fuel and flight inbound on drop tanks, most times tanks were dropped when entering combat (and carried home if no combat) leaving the plane with a similar weight/fuel load as an interceptor near it's base.
For the US the Air Force in the 40s was figuring intercept missions for the early jets with full internal fuel. But their planes held much less fuel than the Navy jets and so needed every drop. The Navy jets could perform a similar length (time) intercept mission with part full tanks and use the increased performance.

Drop tanks open huge cans of worms as not all drop tanks were the same and not all planes carried the same amount of fuel (percentage wise) in drop tanks. F-84s went to four drop tanks (or wing tip tanks plus under wing/fuselage tanks) way before the F-86 did. F-86 stayed with two under wing tanks for a long time. F-84 had wing tip tanks rated for combat when either full or part full?

I'm surprised the USAF cancelled the penetration fighter designs. Those would have been way better off than the F-84.

they were caught in a gamble. The engines didn't improve fast enough and they were either short of power or range. The XP-88 used a pair of 3150lb thrust engines for a 21,000lb airplane (clean) and while after burners were fitted that increased thrust by about 40% and gave good (for it's time) performance, use of the afterburners could double fuel consumption per minute of military power without after burner. The next generation of engines was on the test bench when the prototype penetration fighters were flying.
The Westinghouse J 34 engines used in the XP-88 and XP-90 had a 3.8 to 1 compression ratio compressor in most versions which means fuel economy was not good. Advantages were that it was small (24in diameter) and light (1200-1300lbs) for an axial compressor engine. But with larger single engines offering more power (and perhaps better fuel economy) in the not very distant future tooling up a factory to make one of these aircraft was a big gamble

It produced like 9200 lbf right?

it did but not until 1953-54. The large airflow required also meant it wasn't a drop in replacement.

 

[Zipper730]

They would but I couldn't find SAC or CS sheets for those models. Many of these sheets can be found here : Standard Aircraft Characteristics Arcive

Checked

I think they are as close to "official" or primary source as you are going to get.

They're quite well set-up.

This is not a good assumption, for wartime "intercept" missions most fighters would take-off with max internal fuel.

True enough, but fuel would be burned off during the acceleration, climb, and outbound dash, maneuvering would also be involved in attacking fighters or bombers.

For escort missions the take off was made on internal fuel and flight inbound on drop tanks, most times tanks were dropped when entering combat (and carried home if no combat) leaving the plane with a similar weight/fuel load as an interceptor near it's base.

That I'm aware of

they were caught in a gamble. The engines didn't improve fast enough and they were either short of power or range. The XP-88 used a pair of 3150lb thrust engines for a 21,000lb airplane (clean) and while after burners were fitted that increased thrust by about 40% and gave good (for it's time) performance, use of the afterburners could double fuel consumption per minute of military power without after burner.

Why not just use a pair of J47's? They are similar in weight to the J35, they produce more thrust, and have a better SFC.