wuzak
Captain
Plenty of space for the J-33 if they pit it up front and had exhausts either side of the fuselage.
Fighter: Flop or Not
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I'm thinking no. Not enough time?
According to author Bill Gunston - Kartveli was forced to turn to jet propulsion to combat the German jets and V-1 threat and spent "some weeks" looking at a jet-powered Thunderbolt but considered this too much of a compromise and started a clean sheet of paper design that drew various features from the unbuilt XP-69...
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Just one man's opinion - but Roland Beamont flew the P-80 and F-84 in 1948 and despite describing them as both under-powered the handling of the F-84 was "viceless" and had more potential.
Roland Beamont - Wikipedia
Why then were more single-engined A-series aircraft built?
parsifal
Colonel
I would have to say that at the beginning of its service delivery, it was a failure, but I would draw a distinction of saying it was a flop. A flop to me suggests it had no potential for development, and clearly the f-84 did have potential for that. Its initial failure was brought about by the numerous structural failures that led the new USAF to produce a report that said it was not capable of carrying out any of the assigned roles. That was in 1948 I think, but from 1949, with the introduction of the F-84G and the swept wing version (the F-84F, these issues as well as those relating to its low performance were pretty much addressed. that said, the type continued to experience engine flameout issues in poor weather causing it to be retired early, but kept in reserve. Various emergencies in the early '60s saw it re-enter active service, where corrosion issues forced the expenditure of a lot of man hours to repair that. That could happen to any aircraft really.
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davparlr
Senior Master Sergeant
I've always liked the looks of the F-84. It is the cleanest of all straight wing jet fighters. I think, because of early problems, some surprising for Republic aircraft, it seems to be underappreciated. At the start of the Korean War, the US had four straight wing fighters, the F-80C, F-84E, F2H-2, and F9F-2. All were obsolete as pure fighters by the end of the war. Of these four, the F-84 was faster, by at least 30 mph, using the least powerful engine, better empty to max weight number, and better range. So it was faster, carried more, and went farther than the other three. Very good characteristics. In addition, in comparing the swept wing F-84F to the latest F-86H, it was only a few mph slower, but with 1000 lbs less thrust, capable of carrying 2000 lbs more, and had about 60% greater combat radius. Combining that with inflight refueling and ability to carry nuclear weapons and the F-84 introduced a whole new definition of tactical fighter. It was considered effective in 1961 when it was recalled to duty during the Cuban missile crisis.
- Thread starter
- #27
It seemed a logical starting point. I figured the size of the intake would play a role in determining the size of the intake, I guess I was wrong.
As for the size of the exhaust: I figured the plan was to cut a hole somewhere in the plane's tail and let the exhaust out that way.
According to Bill Gunston, it would appear he took a few weeks.
If that's the real study, then it would appear it was an axial flow design from early on. I didn't think the engine would have been mounted so low in the fuselage. I guess the P-47 wasn't as big as it looked
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- #28
Hawker toyed with the idea of bifurcated intakes and exhausts. I think you'd have to add extra length up front for the intake, and in the back to balance the plane out, but the J33 was a little lighter after all...
What did Winkle Brown think of both?
I'm not sure what time-frame you're talking about, but during the 1930's, Curtiss submitted an unsolicited proposal for a twin-engined attack plane (XA-14), which was actually well-received by the USAAC because it was faster than some fighters, and developed into a pre-production prototype known as the YA-18: It wasn't procured in the numbers desired because of the fact that there wasn't enough funding available for it, so for the time they basically bought single-engined designs, until the A-20 came around.
The USAAC didn't really see the single-engined attack planes as being all that useful because
- They were slow and clumsy compared to fighters, which they felt could do the job as well and be a fighter to boot
- They had little interest in dive bombing and were more interested in strafers, which is why they packed so many guns in their planes
- Their design made them conducive to CAS first, interdiction second, and largely useless for strategic bombing due to the limited range of the aircraft: The USAAC wanted strategic bombing first, interdiction second, and close air-support if they could get around to it
It couldn't dive-bomb, but nobody really cared about that -- strafers all the way! Right? Except WWII started and the Germans showed that they could use dive-bombers with shocking effectiveness, particularly when they were supported by fighters (who'd have ever thought?), and the USAAC even thought "Maybe we should buy some of those...", and they got dive bombers from the Navy.
Then they started developing some of their own
- A-32: It's basic flying characteristics were adequate, but it was too slow, too heavy, and buffeted at high-speed. Though the removal of the rear-gunner seemed a step in the right direction, it's lack of speed meant it'd often be getting attacked from the rear without any protection; the internal bomb-bay seemed a good way to reduce drag, it's top-speed and range didn't seem to have much to show for it though. It also had issues with the exhaust stacks producing excessive glowing at night.
- A-36: Mostly a hook & crook way to get around the fact that the P-51 was built by an American company for a foreign buyer; the A-36 was an American "development" of the P-51 as an attack plane, and I guess by that logic, the P-51B was an American development of the A-36 as a fighter
: Despite the convoluted means to justify it's development (In politics, whether in the US, Canada, the EU, Mexico, Brazil, or Argentina, the argument is more important than the facts), it actually performed pretty well and combined a respectable degree of speed and turning performance with a dive-bomber mission.
- XA-39: It was powered by a R-2800, had a maximum payload of 3000 pounds, a top-speed of 357 mph, and either 4 x 0.50 or 2 x 37mm cannon (might sound like a lot, but compared to the A-32 which had 8 x 0.50 calibur machine guns).
- XA-41: It was basically a huge A-31/A-35 with no gunner and powered by an R-4360. It's top speed was around 354 to 363 mph, and was capable of outmaneuvering a P-51B. Armament was 4 x 0.50 machine guns, or 2 x 37mm cannon, was well as both internal and external provision for 3200 pounds of bombs (while theoretically this would come out to 6400 pounds, it was probably more like 4800 in practice). It's range seemed a little short: 800 miles with a 1,000 pound payload (consider the AD-1, which could achieve a radius of 970 with a ton of payload).
The XB-42 also would have probably had a role in the decision making process too (though I honestly hope they had some method devised for bailing out of that thing as you'd end up like chum if you jumped out).
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- #29
As an attack-plane, not really much as a fighter aircraft. As an attack plane, it was magificent -- no one will argue with you there.
Of course it was beautiful and had clean lines. Usually looks and performance go together, just in this case -- it could have used more agility and a lot less weight.
But not at the beginning -- the F-84 wasn't that good at the beginning.
But how'd it compare in turning performance?
Except that "tactical fighter" usually means a nuclear-strike plane that can fight its way out of a corner if it's got to: The F-105 follows this idea to it's logical conclusion
Shortround6
Major General
post WW II jet engines didn't develop as quickly or as smoothly as some people assumed or hoped. While some engines showed good thrust numbers on the test bench engine life was poor, very poor in many cases and engines were de-rated or held to lower levels in order to get some sort of service life from them. The J-35 engine was started in May of 1943 with a 3,000lb thrust goal. By June of 1943 the goal had been raised to 4,000lbs thrust. the 4,000lbs would not be seen in a service engine until the very late 40s. The -13 engines used in the F-84B,C,D being rated at 3750lbs. Even at this rating the early engines were only good for around 40-50 hours between overhauls which is one reason the early F-84s didn't go to Korea. Some F-84Ds were re-engined with -17B engines in place of the -13s with both improved thrust and engine life. The F-84E may have been the first F-84 with an engine of 4000lbs or more in thrust.
J-35 engines are all over the place in thrust ratings. with dry engines, wet engine, and after burning engines. You also have "nominal" ratings and the ratings they were actually used at.
J-35 engines are all over the place in thrust ratings. with dry engines, wet engine, and after burning engines. You also have "nominal" ratings and the ratings they were actually used at.
buffnut453
Captain
Hawker did rather more than "toy" with the idea of bifurcated intakes and exhausts. They patented the design of the latter and it went into operational service with the Hawker Sea Hawk which is, IMHO, one of the best-looking early jets. There's no need for "extra length up front for the intake" in the design, indeed the whole thing is very elegant:
The bifurcated exhaust design was a vital technological advance that enabled development of the Rolls Royce Pegasus engine that later powered the Harrier (another Hawker product):
- Thread starter
- #32
Oh, I just figured that in some cases the numbers were deliberately fudged or misleadingly listed low.
It's a gorgeous aircraft.
I was talking about a P-47 with a J33 in the nose, the cowling I'd figure would need a slight adjustment to take into effect the extra length of the engine and the need for a smooth airflow to the engine.
I never knew thatThe bifurcated exhaust design was a vital technological advance that enabled development of the Rolls Royce Pegasus engine that later powered the Harrier (another Hawker product):
Shortround6
Major General
Oh boy........
The Curtiss YA-18 also wasn't really that good, it took too long to get going. It was faster than some fighters in part, because it was a monoplane that used retracting landing gear. Just so we are clear. A-18
fighter it was faster than
Please note that the A-18 had fabric covered wings from the main spar back. Using two 9 cylinder radials was a huge drag problem.
Do you have any source for this? or perhaps a time frame? policy often changed within a few years and even swung back to the original in few more more years. In the mid to late 30s the fighters could not carry the desired bomb-loads of the attack planes due to the power of the available engines. US Army also had a different idea of close support than the Germans and no it just wasn't dive bombing as the difference. The US Army wanted large numbers of small fragmentation bombs as the payload. This required internal bomb bays if the drag was not to be excessive. as an example of an attack plane using the same engine as a fighter in the late 30s.
Could carry over 1000lbs over 1000 miles using the same engine as a P-36.
again you need timing to put things in context. The Early A-20 (DB-7) used 1100hp P & W R-1830s and could barely top 300mph. Tis was in a design completion that included the NA-40, the Martin 167 (later Maryland) and the Stearman X-100, the Bell model 9( never made it to harware stage). Looking at the 4 prototypes in the fly-off gives one a better idea of what the USAAC was thinking in 1938/39.
The Curtiss YA-18 also wasn't really that good, it took too long to get going. It was faster than some fighters in part, because it was a monoplane that used retracting landing gear. Just so we are clear. A-18
fighter it was faster than
Please note that the A-18 had fabric covered wings from the main spar back. Using two 9 cylinder radials was a huge drag problem.
Do you have any source for this? or perhaps a time frame? policy often changed within a few years and even swung back to the original in few more more years. In the mid to late 30s the fighters could not carry the desired bomb-loads of the attack planes due to the power of the available engines. US Army also had a different idea of close support than the Germans and no it just wasn't dive bombing as the difference. The US Army wanted large numbers of small fragmentation bombs as the payload. This required internal bomb bays if the drag was not to be excessive. as an example of an attack plane using the same engine as a fighter in the late 30s.
Could carry over 1000lbs over 1000 miles using the same engine as a P-36.
again you need timing to put things in context. The Early A-20 (DB-7) used 1100hp P & W R-1830s and could barely top 300mph. Tis was in a design completion that included the NA-40, the Martin 167 (later Maryland) and the Stearman X-100, the Bell model 9( never made it to harware stage). Looking at the 4 prototypes in the fly-off gives one a better idea of what the USAAC was thinking in 1938/39.
A bit of rearward projection here? I would note that the USMC had shown how to use dive bombing with great effectiveness well before the Germans adopted it. I would also note that nobody really knows how effective the 1938-41 US attack planes would have been in CAS combat because they were never used that way with the original armament and against original defenses. Please note the very early US A-20s (with R-2600 engines) could carry as many as eighty 30lb chemical or fragmentation bombs or sixteen 100lb gp bombs in short range overload condition. The US was certainly NOT depending on strafing only.
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- #34
And was too expensive for the era.
Of course, and the same applied for the Martin B-10's.
That had to do with power-loading and overall range. Regardless, there were some guys in the USAAC that wanted longer-ranged fighters because they could be used as attack planes.
That's why they wanted the bomb-bays? I figured they were always trying to allow a faster cruising speed and range with payload.
As I understand it, the A-20 was a DB-7 derivative the French had interest in with R-2600's. I'm not sure when the R-2600's first flew in the DB-7's.
Not really, there was at least one case where the USAAC specifically asked if the A-20 could-dive bomb, and was told that it was not possible, and a 30-degree dive-angle was the maximum. I want to be clear that I didn't think the A-20's could only strafe: I know they carried bombs. They usually would do level bombing, glide-bombing, which was followed with strafing. The point I was getting at was many attack planes in the USAAC inventory had very large amounts of guns because they were designed with strafing as an additional goal.
The USMC first adopted dive-bombing in 1919 AFAIK.
swampyankee
Chief Master Sergeant
- 4,020
- Jun 25, 2013
I suspect that there was more than one case where domestic developments were ignored until they were used by a foreign power. I don't know if this could have happened with dive bombing and the USAAC (I suspect the answer, if it exists, is complex, e.g., the USAAC may have decided the USMC's experience in dive bombing insurrectionists [or whatever the he** they called them] in Central America wasn't applicable against a European country or Japan, or the USAAC may have found he Marines' evaluation of effectiveness dubious, or the USAAC didn't even know the USMC was doing dive bombing from sources they considered reliable.)
As an aside, the A-36 was probably much better suited to European land combat conditions than were the USN/USMC dive bombers, simply because they would be much less vulnerable to enemy aircraft after dropping their bomb loads. The Lutwaffe found out that Ju87 + enemy fighters was not healthy for stuka pilots -- about the only time the aircraft wasn't vulnerable to fighters was in its dive, but it couldn't dive forever (well, it could. Once).
A second aside: I'm not sure I like the term "flop" when an aircraft is found unsuitable for its original role, but finds success in another role, where by "success" I mean an aircraft, like the F-84, that became a successful attack aircraft, even though it was not a successful fighter. Another example may be the A-5 Vigilante, which was not successful in its original role, but became a successful recon aircraft. Not every aircraft so perfectly matches mission and design as the A-4 or the A-7
As an aside, the A-36 was probably much better suited to European land combat conditions than were the USN/USMC dive bombers, simply because they would be much less vulnerable to enemy aircraft after dropping their bomb loads. The Lutwaffe found out that Ju87 + enemy fighters was not healthy for stuka pilots -- about the only time the aircraft wasn't vulnerable to fighters was in its dive, but it couldn't dive forever (well, it could. Once).
A second aside: I'm not sure I like the term "flop" when an aircraft is found unsuitable for its original role, but finds success in another role, where by "success" I mean an aircraft, like the F-84, that became a successful attack aircraft, even though it was not a successful fighter. Another example may be the A-5 Vigilante, which was not successful in its original role, but became a successful recon aircraft. Not every aircraft so perfectly matches mission and design as the A-4 or the A-7
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michaelmaltby
Colonel
Did the Marines ever use their Corsairs as 'dive' bombers?
Shortround6
Major General
Can you be a bit more specific as to when this was? In the 30s the US wanted more range simply for deploying the fighters around the country. The tank behind the pilot's seat on the P-36 and early P-40s was an overload tank for ferrying or long range missions, to be used first before combat was joined or not even filled for intercept missions.
Different way of saying the same thing. More drag means lower cruising speed and shorter range. Lots of small bombs have lots more drag than a few big bombs. P-51D with two 500lb bombs is still pretty slick. P-51 with under wing rockets is like deploying a parachute.
we are also back to the rapid pace of engine and aircraft development. The YA-18 was being delivered in the summer of 1938 with 930hp engines, in four years engines of 1700-2000hp were available. That plus the rapid development in flaps (from split to double slotted) and in airfoils allowed the possibility of single engine aircraft to have the speed, payload and range of twin engine planes only few years older.
The USAAC, having had a four plane fly-off, decided that none of the planes met new, revised needs. They had Douglas modify the DB-7 design to use R-2600s ( using turbo chargers). North American used the NA-40 as the basis (considerably modified ) for their submission for the medium bomber competition and it became the B-25.
Douglas was able to offer non-turbo R-2600 powered DB-7 versions to the French and British due to work already done for the USAAC version even though it hadn't flown at the time. Production for the different customers were somewhat mixed together.
To confuse things further the A-20A flew with non-turboed R-2600s several months before the turboed A-20 no letter, and both flew before the first DB-7B with R-2600.
The US didn't use any R-1830 powered A-20 type planes. However 3 of the four planes in the fly-off were powered by them (the fourth used P & W R-2180s) so the performance they were looking for in 1938 can be judged by them.
There very well could have been an inquiry from somebody in the USAAC asking if the A-20 could dive bomb but I doubt it was from any engineering officer worth his slide rule. Dive speeds and "G" loadings were known pretty well near the beginning of the project and no twin engine bomber/attack plane was built to handle 6 "G" plus pull outs without much heavier reinforcement, see JU-88 and the saga of German dive bombing twins. There may have been an inquiry as to if was possible to modify the A-20.
Shortround6
Major General
Yep,
Yes it is a Vought Corsair
The pilot in the picture won the congressional medal of honor for his flying exploits in Nicaragua in 1928, although not for dive bombing. It is a little hard to believe the USAAC could have remained ignorant of Dive bombing given what was going on during the late 20s and early 30s.
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.
- Thread starter
- #39
Used in a way they saw to be effective...
That's odd...
They were faster and more agile
Unless they were covered by fighters.
Okay, but regardless, it wasn't a good fighter. Frankly it should have either been re-designated as BF-84 (they didn't use the attack category anymore) or B-55 (an attack plane is a bomber unless it's a gunship).
Unsure...
Yeah but I figured they were using a few 100 pound bombs instead of a whole lot of 30 pound bombs.
Which is a point I was trying to make: In 1935 it made sense, but by 1942-1944, it didn't.
Not exactly, there was the A-20 and A-20A. The first was a high altitude fast-bomber; the latter a low/medium altitude level bomber and strafer.
Far as I know it wasn't from the engineering guys...
Shortround6
Major General
The Army tried using single engine Navy dive bombers early in WW II but lost interest real quick. A big problem was range. In the South Pacific the single engine planes just didn't have the needed range to operate island to island. Even the A-20 was bit lacking.
In North Africa they might have worked but the problem here was the opposite, ranges were so close that fighters could carry bombs and reach many of the desired targets. This changed with the invasion of Sicily when fighters from North Africa could not support the invasion forces. Once air Bases were established on Sicily the fighters were good support aircraft again.
However with new planes taking around 3 years to go from design to operational use trying to predict where your airfields will be in relation to your enemy in 3 years gets a bit tricky. 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.
Of course with mid to late war single engine attack aircraft using R-2800s, R-3350s and R-4360s the available power was well in excess of of what even the SD2C/A-25 had. You also had twin engine medium bomber/attack aircraft in the inventory to handle the really long range missions.
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. As in indication of how things changed the J-33 engine in the F-80 was good for about 40 hours in 1947-48. the J-35 in the F-84 wasn't any better. By the late 1950s the last J-33s being built were rated for 1400 hours between overhauls. A 35 times increase in 10 years for the same basic design while giving 25-50% more thrust.
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.
How much the F-84 was held back by the J-35 engine I don't know but the J-35 power level stayed static for several years. Unfortunately for the F-84 those few years saw the introduction of swept wings and also saw the introduction of the J-47 engine. At which point they tried to play catch up with the F-84F.
BTW, just about every USAAC attack aircraft in the 1930s had four .30 cal guns for strafing, while more than some other Attack/close support aircraft it was hardly overwhelming or even that great a portion of the payload compared to the 1941/43 designs. The A-20s, as they left the factory, rarely had more than four .30 cal guns until the first "G" models in Feb 1943. A number of them were up-gunned in the Field much like the B-25s but that is not a reflection of USAAC policy or doctrine of 1940/41.
In North Africa they might have worked but the problem here was the opposite, ranges were so close that fighters could carry bombs and reach many of the desired targets. This changed with the invasion of Sicily when fighters from North Africa could not support the invasion forces. Once air Bases were established on Sicily the fighters were good support aircraft again.
However with new planes taking around 3 years to go from design to operational use trying to predict where your airfields will be in relation to your enemy in 3 years gets a bit tricky. 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.
Of course with mid to late war single engine attack aircraft using R-2800s, R-3350s and R-4360s the available power was well in excess of of what even the SD2C/A-25 had. You also had twin engine medium bomber/attack aircraft in the inventory to handle the really long range missions.
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. As in indication of how things changed the J-33 engine in the F-80 was good for about 40 hours in 1947-48. the J-35 in the F-84 wasn't any better. By the late 1950s the last J-33s being built were rated for 1400 hours between overhauls. A 35 times increase in 10 years for the same basic design while giving 25-50% more thrust.
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.
How much the F-84 was held back by the J-35 engine I don't know but the J-35 power level stayed static for several years. Unfortunately for the F-84 those few years saw the introduction of swept wings and also saw the introduction of the J-47 engine. At which point they tried to play catch up with the F-84F.
BTW, just about every USAAC attack aircraft in the 1930s had four .30 cal guns for strafing, while more than some other Attack/close support aircraft it was hardly overwhelming or even that great a portion of the payload compared to the 1941/43 designs. The A-20s, as they left the factory, rarely had more than four .30 cal guns until the first "G" models in Feb 1943. A number of them were up-gunned in the Field much like the B-25s but that is not a reflection of USAAC policy or doctrine of 1940/41.
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