Fighter: Flop or Not

[Zipper730]

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).

 

[pbehn]

No idea about the Sabre but the number of pilots and planes lost in early days of jets due to running out of fuel tells me that most pilots would take thick wings with fuel in them.

 

[Zipper730]

No idea about the Sabre but the number of pilots and planes lost in early days of jets due to running out of fuel tells me that most pilots would take thick wings with fuel in them.

Didn't the Sabre have a combat radius of around 600-700nm?

 

[FLYBOYJ]

The F-84 was eclipsed by fighter development during the late 1940s. It was obvious by the Korean War the earlier models were not going to compete with the MiG-15 and like the F-80 it was used as a fighter bomber where it served well. The F-84F was playing catch up but was "too little, too late," was heavy and underpowered. The F-84G served well and I think if you sold over 7000 of them the aircraft was far from a flop.

 

[FLYBOYJ]

Didn't the Sabre have a combat radius of around 600-700nm?

1,525 mi range according to Wiki

 

[swampyankee]

Most of the jet aircraft of its generation were flops to some extent or another; technology was changing so fast that something spec'd as a world-beater January would be a middle-of-the-pack in May and old-fashioned in December. I think another problem may have been that the engineering culture at Republic was too conservative to adapt to the jet age. North American's engineers seemed to get jet fighters right faster than its competitors in the West, as did Boeing with jet bombers.

I would not call the F-84 a "flop," but it was a far better attack aircraft than fighter.

 

[pbehn]

Zipper you said this

• 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).

And this

Didn't the Sabre have a combat radius of around 600-700nm?

I was merely stating that in view of the short range and huge number of accidents with early jets running out of fuel that "most pilots would take thick wings with fuel in them." I think those buying the planes would too. remember in those days ejector seats didnt work close to ground.

 

[tyrodtom]

The F-84 was never designed as a interceptor, it was designed as a replacement for the P-47, which was originally designed as a interceptor, but was used as a bomber escort, but was best used as a fighter- bomber. The F-84 was designed to replace the P-47 as it was used.

And for a failure there sure were a lot of them used by our allies during the cold war era. Hundreds each by Denmark, Norway, Taiwan, France, Turkey, Greece, and several others, even strangely enough, Yugoslavia.

And once it got some swept wings with the F-84F model, it wasn't so slow either.
Not the best jet of it's era, but not a failure.

 

[Shortround6]

As SwampYankee has stated, if not in so many words, timing is important.

The F-84 first flew on Feb 28th 1946. A rather important distinction as this was before such planes as the Supermarine Attacker (which used a Supermairine Spiteful wing) It may have been before the Yak -17. It was 9 months before the NA FJ-Fury (with a straight wing) and 19 months before before the first F-86 Sabre. In fact production F-84Bs were being delivered to squadrons before the XP-86 ever flew.
It was over 10 months months before the McDonnall F2H and about 20 months ahead of the F9F.

Some books have said it had a "relatively" thick wing, key word being relatively as the wing was 12% in thickness which means it was thinner than most WW II piston engine fighter wings.
As far as the armament goes, from the F-84Bs being delivered in the summer of 1947 onward the F-84 used six of the fast firing (1200rpm) M3 machineguns which meant it was equal to NINE WW II .50 cal machineguns. The intended change to to the M23 incendiary ammo (much larger filling of incendiary material ) may have helped equalize things somewhat (Navy did go to faster firing 20mm guns).

Yes the F-84 suffered a number of problems in service for several years but then it was really the USAAFs 2nd jet fighter to go into widespread service and many other early jets also went through considerable modifications and upgrades to become effective aircraft.

I would also caution about comparing one airplane against another using basic designations like F-84 vs F2H as the F-84 not only changed capabilities it went from 4000lb thrust engines on the B to 5600lb thrust engines on the G and the F2H went from a pair of 3000lb thrust engines to a pair of 3600lb thrust engines in the -4 model, there were also two fuselage stretches , the first of 1ft 1 1/2 inches (from the -1 to the -2) and the 2nd of 2ft 7 in (-2 to -3) to accommodate more fuel.

Obviously capabilities of the various "dash" models varied considerably.

 

[Zipper730]

The F-84 was eclipsed by fighter development during the late 1940s.

I'm not sure that's an entirely accurate statement: It was inferior to the P-80, which was built earlier in terms of climb and agility. The plane had numerous structural problems, which required increasing structural weight which took away from performance.

It could fly far and carry a load a decent distance, which made it useful as a fighter-bomber. The fact remains that it was sort of a way to salvage a fighter that wasn't able to hack it well enough as a fighter.

The F-84F was playing catch up but was "too little, too late," was heavy and underpowered.

As for playing catch-up, you could say the same thing about the FJ-2/-3, and F9F-6. The F-84F's problem wasn't just weight: It also had to do with the wings, they didn't make them big enough, and it seemed to be about the same as the regular F-84 (just faster).

The F-84G served well

As a tactical-bomber...

I think if you sold over 7000 of them the aircraft was far from a flop.

I'm not sure how popular this statement will make me, but this is a bit more complicated: The USAF didn't see attack planes as being useful unless they were twin-engined.

In the 1930's this made-sense because they were on the slow-side (though to some extent, there were policy decisions that affected this as well); by the time World War II rolled along, engines like the R-3350 and R-4360 made it possible to make a single-engined attack plane work, but they didn't want them -- The USAAF/USAF didn't really see attack planes as being useful unless they were basically twin-engined aircraft and dictated substantial payload and range requirements that were beyond what were needed of a tactical-bomber.

Most of the jet aircraft of its generation were flops to some extent or another

I'm not an authority on all early jet-aircraft, but there's some truth to that. The F-80 seemed much better when it came to climb and agility however. The F2H & F9F seemed better (could be wrong).

I would not call the F-84 a "flop," but it was a far better attack aircraft than fighter.

As an attack-plane it was very good, but that's not a fighter though...

The F-84 was never designed as a interceptor, it was designed as a replacement for the P-47, which was originally designed as a interceptor, but was used as a bomber escort, but was best used as a fighter- bomber.

If I recall correctly, the XP-47A was designed as a lighter weight fighter more like the designs seen in Europe (Spitfire, Me-109), which were effectively interceptors; Republic wanted something bigger, with more firepower and longer-range, and that became the XP-47B (which was a totally different plane): The range of the P-47 ironically wasn't so good at first, but that progressively improved with time...

The roots of the F-84 started out as a P-47 with the radial removed, and a jet-engine installed in the plane: That wasn't workable because the centrifugal flow engines we had weren't adequate for the task, they were too plump even for the P-47. As time went on, they came up with a new design, using an axial flow engine to be an interceptor, far as I know.

 

[wuzak]

The roots of the F-84 started out as a P-47 with the radial removed, and a jet-engine installed in the plane: That wasn't workable because the centrifugal flow engines we had weren't adequate for the task, they were too plump even for the P-47. As time went on, they came up with a new design, using an axial flow engine to be an interceptor, far as I know.

I suppose if the engine was in the mid fuselage it might be a bit big, but the Allison J33 fitted in the P-80 and was smaller in diameter than the R-2800.

 

[Shortround6]

It is a little hard to say what was going on in the early stages or what the goals were. Different accounts do not agree 100%, especially as to what Republic was offering vs what the Air Force wanted. One account claims the Air Force told Republic to use the axial flow engine.
In any case three prototypes and 400 production planes were ordered in March of 1945 but in the usual round of cancellations and reinstatements at the end of WW II the program was delayed.

In one sense the the USAAF was stuck with the F-84 as it was in production in large numbers before the F-86 and canceling it and trying to retool the factories and all their suppliers would have caused a massive delay in planes delivered in the time period of post Berlin Crises and early Korean war.
The F-84 was partially crippled by the J-35 engine which took too long to reach higher levels of power at acceptable overhaul life.
Also be sure you are comparing apples to apples as some performance listings for the F-84 (like climb) sometimes are for the plane in strike mode or with drop tanks. Being under powered it's climb rate was very dependent on weight but it could reach 30,000ft in about 12.2 minutes when loaded and operated as an "interceptor" for a F-84D with a 3750lb thrust engine.

 

[tyrodtom]

The F-84 was designed to meet a USAF general operation requirement for a day fighter with a top speed of 600 mph. It met that.

What is the USAF's exact definition of a "fighter", not Zipper730's definition, or mine, but the USAF's ?

The F-80 had a shorter take off roll, better low altitude climb rate, and was more maneuverable. The F-84 had a higher bomb load, was faster, and had better high altitude performance.

As a side note, the F-84 was the first single place aircraft that could deliver a nuke, and according to the USAF, of all the ground targets destroyed by aircraft during the Korean action, 60% were taken out by the F-84.

Early models of the F-84 had problems, but so did early model F- or P-80's .

 

[Shortround6]

Again, over time, roles changed and capabilities changed.

The F-84Ds "mission" was described as " The Principal mission of the F-84D is the destruction of hostile aircraft, it is also designed to function as a fighter-bomber and escort fighter."

This is from a USSAF standard aircraft characteristic sheet dated Jan of 1950 as shown here:

http://www.alternatewars.com/SAC/F-84D_Thunderjet_SAC_-_20_January_1950.pdf

other standard aircraft characteristic sheets are available and the one for the F-84E block 25 and 30 shows a climb of 8.3 minutes to 30,000ft from a standing start on the runway. Of course this version had a 5200lb thrust engine vs the 3750lb thrust engine in the D.

By the time you get to the F-84G I don't know what they were saying the principal mission was.

 

[FLYBOYJ]

I'm not sure that's an entirely accurate statement: It was inferior to the P-80, which was built earlier in terms of climb and agility. The plane had numerous structural problems, which required increasing structural weight which took away from performance.

It was accurate and was designed under an entirely different design spec than the P-80. It did have issues but many of those issues were worked out

As for playing catch-up, you could say the same thing about the FJ-2/-3, and F9F-6. The F-84F's problem wasn't just weight: It also had to do with the wings, they didn't make them big enough, and it seemed to be about the same as the regular F-84 (just faster).
As a tactical-bomber...

They as well, look how long they were in service.

I'm not sure how popular this statement will make me, but this is a bit more complicated: The USAF didn't see attack planes as being useful unless they were twin-engined.

By the late 40s/ early 50s that was not really true.

I'm not an authority on all early jet-aircraft, but there's some truth to that. The F-80 seemed much better when it came to climb and agility however. The F2H & F9F seemed better (could be wrong).
As an attack-plane it was very good, but that's not a fighter though...

It was a fighter bomber. It's primary mission was to drop bombs and then had a secondary role as an air to air fighter (which it was not the best at) It did shoot down 8 MiG-15s but over 60 were shot down by MiG-15s, mostly when they were attacking ground targets.

The roots of the F-84 started out as a P-47 with the radial removed, and a jet-engine installed in the plane: That wasn't workable because the centrifugal flow engines we had weren't adequate for the task, they were too plump even for the P-47. As time went on, they came up with a new design, using an axial flow engine to be an interceptor, far as I know.

Errrr, no. You just don't remove a round engine and start building a jet. the F-84 ( Republic Model AP-23) started out as a jet from the get-go. Do you know who Alexander Kartveli was?

 

[fubar57]

Nice Joe730

 

[Zipper730]

I suppose if the engine was in the mid fuselage it might be a bit big, but the Allison J33 fitted in the P-80 and was smaller in diameter than the R-2800.

You're right: I have the numbers with me right now

R-2800
Diameter: 52.8"
Length: 81.4"
Weight: 2360 lbs.

J33
Diameter: 50.5"
Length: 107"
Weight: 1820 lbs.

I'm not sure what to make of this, unless the engine was re-positioned to the mid-fuselage instead of the forward fuselage, or the USAAF just didn't like the idea of a P-47 with a jet-engine and wanted a new aircraft.

It is a little hard to say what was going on in the early stages or what the goals were. Different accounts do not agree 100%, especially as to what Republic was offering vs what the Air Force wanted.

Do you have anymore information on this subject? I'm curious about trying to tease out what's true and not.

One account claims the Air Force told Republic to use the axial flow engine.

That might very well be true

In one sense the the USAAF was stuck with the F-84 as it was in production in large numbers before the F-86 and canceling it and trying to retool the factories and all their suppliers would have caused a massive delay in planes delivered in the time period of post Berlin Crises and early Korean war.

The F-80 was still in production?

Also be sure you are comparing apples to apples as some performance listings for the F-84 (like climb) sometimes are for the plane in strike mode or with drop tanks. Being under powered it's climb rate was very dependent on weight but it could reach 30,000ft in about 12.2 minutes when loaded and operated as an "interceptor" for a F-84D with a 3750lb thrust engine.

The F-80C could reach 25,000 in 7 minutes. I'm not sure if that was from a standing start on the runway, or from liftoff, and I'm uncertain how much more time it would take to reach 30,000 feet. Though I figure it would probably only take somewhere between 1 and 3 minutes.

Again, over time, roles changed and capabilities changed.

Of course, from fighter-interceptor, to fighter-bomber.

By the time you get to the F-84G I don't know what they were saying the principal mission was.

Nuclear strike...

The F-84 was designed to meet a USAF general operation requirement for a day fighter with a top speed of 600 mph. It met that.

That's correct...

What is the USAF's exact definition of a "fighter", not Zipper730's definition, or mine, but the USAF's ?

No idea, but as a general rule a fighter is an aircraft designed for high speed and acceleration, a good rate of roll, and turn, as well as a good rate of climb.

The F-80 had a shorter take off roll, better low altitude climb rate, and was more maneuverable.

Yes

The F-84 had a higher bomb load, was faster, and had better high altitude performance.

When you say high altitude performance, does that mean better agility at altitude, merely speed at altitude?

according to the USAF, of all the ground targets destroyed by aircraft during the Korean action, 60% were taken out by the F-84.

Yup

It was a fighter bomber. It's primary mission was to drop bombs and then had a secondary role as an air to air fighter

I would have thought, at the penalty of appearing ignorant, that a fighter-bombers primary job was to be a fighter, that could be used as an attack-plane.

Do you know who Alexander Kartveli was?

Chief engineer, Republic

 

[tyrodtom]

It's funny you would list the diameters of the 2 types of engines.
It seems you're not even considering the fact that jet engines require quite large intakes, and exhaust.

I'm sure Kartveli maybe took about one day's thought to see that putting a jet engine in a P-47 fuselage wasn't going to work.

 

[fubar57]

 

[tyrodtom]

So it took a few months ! But just a paper study surely ?

I bet the pilot would feel real comfortable sitting right over where the compressor blades would fly if they failed.

Sort of like the early Yak, and Mig jets.