Fighter: Flop or Not

[davparlr]

2. Once again you fail to say which versions of which aircraft you are comparing to.

An error often made in comparisons. Another common error is comparing performance at gross weight, e.g., in comparing a Mustang to a Bf 109, the Mustang would be carrying 269 gallons of gas compared to the Bf 109 carrying 105 gallons, skewing actual performance capability. For the model comparisons I used, I picked the models operational at the start of the Korean War, 1950. This was the time when late WWII types and early jet's metal was was going to be tested in the crucible of war.

The period of time from 1945 to about 1957 is of great interest to me due to amazing demands that advancing technology made on engineers, piloting procedures and training, and planning mission planning. Also, probably because my interest in modeling was peaking at that time!

In those 12 years jet aircraft went from stumbling along with poor operational direction to what I consider modern application. By 1957 the century series jets, the F8U, and the KC-135 had flown. The J57, J79, and the J75 engines had been run and produced. Operational concepts were pretty well established. Performance wise, airspeed had gone up from 500-600 mph to 1500+ mph, approach speeds went up from 100 mph to 200+ mph, max altitude from 30-40k ft to 80+k ft. Throttle response went from an almost instantaneous 2800 hp kick in the rear to, well, I'll get a little push in a minute or two, and then back to OK, that afterburner really kicks in. All of these required significant adjustments to pilot training and operations (I'm reading "Night Fighters over Korea", and the F3D Skyknights were banned from many airfields because the engines were canted down and tended to melt the taxiways.)

Engineering wise, the challenge was even more difficult. Major change to engines and the appearance of new aerodynamic problems associated with its increase in speed capabilities all caused intense effort. Conquering trans-sonic problems with swept wings and Whitcomb area rule, new challenges in inlet duct design to handle mach airflow, and new requirements to design exhaust nozzles was intensive. Knowing all the problems of defeating the "sound barrier", it amazed me how effortless the T-38 went through the sound barrier. You had to work at not doing it while flying aerobatics. Work was done on improving the operational envelop with canted decks on carriers to inflight refueling. Avionics was leap frogging. I'm sure it was exciting time to be working in the aeronautical field, as a pilot and as an engineer. Today, we can't even build an airplane in 12 years!

 

[XBe02Drvr]

Today, we can't even build an airplane in 12 years!

Today we can't build an airplane unless it's a DO EVERYTHING machine!
Cheers,
Wes

 

[swampyankee]

Today we can't build an airplane unless it's a DO EVERYTHING machine!
Cheers,
Wes

....does everything AND has every shiny new piece of bleading edge technology.

 

[Zipper730]

You keep posting the F-84 was designed as a interceptor, and was a failure as a interceptor.

It was designed to a late 1944 General Operational Requirement for a day FIGHTER capable of 600 mph, and a 700 mile range.

Where did you get this from?

2. Once again you fail to say which versions of which aircraft you are comparing to. Climb-performance of the F-84 varied considerably between the B-C- early D models (around 4100fpm for initial climb) to the late D-E (6000-7050fpm) to the G (initial climb unknown but time to 35,000ft 9.4 minutes).

I was just using the only available data I had for the F-84G

Supermarine Attacker is a real stretch, 3rd prototype doesn't even fly until Jan 1950. Pretty poor interceptor in 1948-49-50 if it is not in squadron service.

I was just trying to list anything that was built in the same time period

Hawker SeaHawk, doesn't enter squadron service until 1953.

I was just looking at when it first flew

I would also note that the first duty of an escort fighter is to actually show-up where the bombers are.

But the F-80, F-84, and F-86 could all do that...

 

[Shortround6]

But the F-80, F-84, and F-86 could all do that...

Really?????

F-80C could hold 425 gallons inside and totaled either 885 gal or 955 gallons of fuel depending on the size of the drop tanks.
F-86F-20 held 435 gal inside and pair of 200 gallon drop tanks. 835 gallons total.

F-84E held 452 gallons inside and a total of 920 gallons in four external tanks, total 1372 gallons The wing tip tanks being rated for combat, either no or few restrictions on speed or maneuvers?

Before air to air refueling, which most (all?) F-84Gs could do, which plane makes the better "escort" fighter.

Granted the earlier F-84s could only use two drop tanks.

 

[Zipper730]

Really?????

They could all make it to the rendezvous point... they might not be able to stay all the way, but they could make the rendezvous

 

[fubar57]

Not much good then. Show up at the rendezvous, say "adios", bug out and leave the bombers at the mercy of EA

 

[Shortround6]

Spitfires could do that in WW II and didn't even need drop tanks

 

[tyrodtom]

Zipper730, where did you get that the F-84 was designed as a interceptor ??

I get that it was designed for other requirements in " Kartveli, innovator in aviation" also Wiki, and off line in Janes , 1951.

 

[Zipper730]

Zipper730, where did you get that the F-84 was designed as a interceptor??

I'd have almost sworn it was joebaugher and wikipedia, but it's not there... weird.

I get that it was designed for other requirements in "Kartveli, innovator in aviation" also Wiki, and off line in Janes, 1951.

Ok

 

[pbehn]

I'd have almost sworn it was joebaugher and wikipedia, but it's not there... weird.

Zipper, the most unreliable source possible is what you thought you read on wiki, please just check it is there before posting.

 

[Shortround6]

The F-84 may have started as an interceptor, without original project notes it is hard to say, but this would have been the converted P-47 version.
From Joe Baugher's web site

"
he series had its origin in a 1944 company-financed design study for a jet-powered replacement for the famed P-47 Thunderbolt. At first, Alexander Kartveli and his team at the Republic Aircraft Corporation considered a straightforward jet adaptation of the P-47 airframe, but soon decided that such a design was impractical and began over again from scratch. They settled on a cantilever low-wing monoplane with straight, laminar-flow wings and cantilevered horizontal tailplanes mounted halfway up the vertical tail. A large airbrake was to be installed in the belly of the aircraft, just underneath the cockpit. The engine selected was the General Electric TG-180 (J35) turbojet. This engine had an axial flow, which offered less fuel consumption than that of the centrifugal-flow engines of earlier jet fighters such as the Lockheed P-80 Shooting Star. The smaller diameter of the axial-flow engine had the additional advantage in that it allowed the use of a more streamlined, low drag fuselage. The intake for the jet engine was to be mounted in the nose. The pressurized cockpit was to have a teardrop canopy and was to be equipped with an ejector seat.

Since range as well as high speed was an important consideration, it was necessary to forego a thin profile wing in favor of an airfoil section that was thick enough to carry fuel tanks and landing gear. The critical Mach number of this wing was considerably lower than that of the fuselage, and was the primary limiter of performance on early P-84 models.

The USAAF liked what they saw, and ordered three prototypes and 400 production examples in March of 1945."

Notice the bolded parts (by me) and what they mean. The Axial flow engine/s offered/promised better fuel consumption. They didn't actually deliver better fuel consumption for a number of years. Also note that a J35 weighed about 2400lbs for 4000lbs or less thrust while the J33 in the F-80 weighed about 1875lbs for 3825lbs thrust, a DH Goblin weighed 1500lbs for 3,000lbs thrust the Ghost went 2010lbs for 5000lbs thrust, A Derwent V went around 1250lbs for 3500lbs of thrust.

For a fast climbing "interceptor" the Axial flow engine was NOT the way to go in 1945-46-47.
If you were trying for a long range aircraft you went for the axial flow engine. Better fuel consumption would cancel the extra engine weight on long range flights and the more streamline engine would offer lower drag further improving range.
For actual results the better fuel consumption remained an illusion for most/all of the 1940s but it was too late to change engines (and the engine makers were all promising that the next revision/modification would improve the fuel consumption

 

[Zipper730]

Zipper, the most unreliable source possible is what you thought you read on wiki, please just check it is there before posting.

Well, Wikipedia generally is: Joebaugher seems more reliable. As for the interceptor claim, I either misremembered, or a disruption in the space-time continuum occurred J/K, whereby somebody retroactively edited a few online articles J/K.

The F-84 may have started as an interceptor, without original project notes it is hard to say, but this would have been the converted P-47 version.

I doubt it, the P-47 variant was underpowered as hell...

 

[Zipper730]

With all that covered... what do you guys think of the F7U? Flop or not?

 

[fubar57]

Over a quarter destroyed in accidents and responsible for over 20 pilot deaths???????????????????????????????????????

EDIT: forgot a question mark

 

[fubar57]

......the alphabetized list of what is wrong with the XF7U-3 is so long, they had to start the alphabet over: "d. Pilots with short arms have difficulty reaching the power lever in the MAXIMUM thrust position. Also, 3 years or so of squadron service hardly makes for a successful aircraft

 

[Shortround6]

Wiki actually sums it up.
"The poor safety record was largely the result of the advanced design built to apply new aerodynamic theories, insufficient thrust and unreliable engines."

How much of the blame is due to the engines? and how much to the layout of the aircraft?

Using low thrust and unreliable engines in an airframe that doesn't fly the same way conventional aircraft do at low speeds is a recipe for disaster. For example the F-102 was lighter (clean) had a lot more wing area and it's reliable single engine gave over 25% more thrust (non afterburning) than the two engines in the F7U. They also weren't trying to operate it from a carrier deck.

The J40 engine was even worse and Westinghouse went out of the Jet engine business effectively in 1955-56 although legacy support for engines already built kept the doors open until 1960 after which the doors closed and any remaining personnel went to the industrial gas turbine division.

 

[swampyankee]

The USN had more than one not-entirely successful aircraft in that generation,but the F7U Cutlass was probably the worse.

 

[Shortround6]

Depends on what you call a generation but they certainly had a number of less than successful jets over a period of around 10 years.

A good deal of the problems stem from being underpowered and most of the underpowered or planes that were late entering service use Westinghouse engines.

In an amazing display of inter-service co-operation (sarcasm) General Electric/Allison produced engines for the Air Force, Westinghouse made engines for the Navy and P & W after licencing Rolls Royce engines did sell to both. On occasions this arrangement was broken but usually only after the original engine for a design didn't work and they were looking for a substitute.

By the mid 50s the Navy had lost all faith in Westinghouse and went to GE and P & W engines. Allison had also dropped out of the turbo jet business but remained in the turbo prop area.

 

[swampyankee]

Westinghouse's AGT division's history should be studied in business schools as an example of how not to do it.

One place to find out a bit is http://enginehistory.org/GasTurbines/EarlyGT/Westinghouse/WestinghouseAGT.pdf
I'd recommend looking farther, but to some extent it seems that Westinghouse's gas turbine failure can be lain at the feet of management that's quite short-sighted. I think Curtiss-Wright had the same problem, especially post WWII.