Did the Wildcat airframe have any growth left in it?

[Shortround6]

Part of this question comes up to timing.

The 4 bladed prop to solve the landing gear problem for one. About the earliest 4 bladed prop (modern prop) used by the US was the one on the B-26. You could fasten much smaller blades to that hub I guess. The engines may use the same spline on the prop shaft. The P-47 followed.

Other problem are when do you do this and why? If you do it in 1941-42 you are going to delay the F6F (which was designed for the R-2600 in the first place)
And by using the R-2600 you are (although perhaps unknown at the time) creating a low altitude fighter. What ever performance advantage you have at low altitude ()-15,000ft) will pretty much disappear over 20,000ft unless you use some version of the R-2600 that never made it into production. Like the ones planed for the A-20 (turbo charger) or the XF6F (mechanical two stage) but then you have even heavier engine installations that need more volume. The turbo version in the A-20 had severe cooling troubles. The two stage mechanical in the F6F is an unknown (only 3 made?)

Wildcat was probably the biggest and heaviest 1-engined 1-seat fighter when introduced. Wing was bigger than on the 2-engined Whirlwind or Ro.57.

That is true but it is only 2.5 sq ft larger than a Hurricane (1%) and the Wildcat had 2 feet less wingspan. The US Navy had some pretty strict landing requirements. Like a stall speed of 70mph. which means the vast majority of European fighters couldn't do it's job. The F4F also carried a greater weight of guns and ammo than all the fighters you mentioned except for the FW 190 and perhaps the Macchi 205.

The F4F may give the appearance of being small when lined up next to the F4U, F6F and TBF. (which used a larger wing than the A-20 and the Mosquito.)

It's appearance on the ground/deck teetering around on that landing gear

doesn't give the same impression of size, strength that the Hawker Typhoon does

 

[tomo pauk]

...
That is true but it is only 2.5 sq ft larger than a Hurricane (1%) and the Wildcat had 2 feet less wingspan. The US Navy had some pretty strict landing requirements. Like a stall speed of 70mph. which means the vast majority of European fighters couldn't do it's job. The F4F also carried a greater weight of guns and ammo than all the fighters you mentioned except for the FW 190 and perhaps the Macchi 205.

The F4F may give the appearance of being small when lined up next to the F4U, F6F and TBF. (which used a larger wing than the A-20 and the Mosquito.)

It's appearance on the ground/deck teetering around on that landing gear
doesn't give the same impression of size, strength that the Hawker Typhoon does

No quarrels with your post.
My intention was point out that Wildcat, when introduced, was not a small fighter, but rather the opposite.

 

[GreenKnight121]

In response to Shortround6 post#32,

I figured minus 200 lbs for the removal of the 2x .50 cal Browning and ammunition, and plus 650 lbs for the new engine and propeller, and plus 150 lbs for the detail strengthening. So total weight gain is about 600 lbs.

The loss of the 2x .50 cal was not intended to change the CG, only reduce the weight gain. I could not find any other acceptable weight reduction measures that would not entail significant reduction in operational effectiveness.figure that

I realize that in order to figure the CG change you would have to do a detail design analysis to see if it were possible to realize an acceptable CG. If it were possible the results would be more or less as listed in my post#30.

The reversion to 4x .50mg was NOT to reduce weight, or any reason other than to increase firing time!

The F4F-3 had the 4-gun armament, with 450 rounds per gun (1,800 rounds total). The F4F-4 went to a 6-gun armament, with only 240 rounds per gun (1,440 rounds total) - which also reduced firing duration from ~34 seconds (gun fire rate ~800rpm) to 18 seconds.

While this armament hit 50% harder, it lasted only 53% as long, and was strongly disliked by many pilots. A work-around was provided where the pilot could disable the outer 2 guns until the inner 4 were out of ammo, then switch to the outers, but this was a poor fix at best.

The FM-1 & FM-2 reverted to the 4-gun 450rpg fit - so you need to figure the actual ammo weights with 4 guns and with 6.

The AN/M2 fitted in aircraft weighed 61 lb (28 kg) each complete (no ammo).
So the gun weights were 244 lb for the 4-gun and 366 lb for the 60gun, but the 4-gun had 1,800 rounds (plus connecting links) while the 6-gun had only 1,440 rounds (with links).

 

[Shortround6]

No quarrels with your post.
My intention was point out that Wildcat, when introduced, was not a small fighter, but rather the opposite.

Well, for the British, the Wildcat was replacing/supplementing the Blackburn Skua and the Fairey Fulmar and the Wildcat was certainly small compared to them.

Everything is relative and the WIldcat was larger than most shore based single engine, single seat fighters of 1940-41. But it was a small aircraft on many carrier decks surrounded by the much larger strike aircraft.

 

[ThomasP]

In response to GreenKnight121 post#43,

Please read my post#30 & post#34 more carefully? I thought I was clear, but if not my apologies.

My removal (not General Motors removal) of the 2x .50 cal has nothing to do with why it was done on the FM-2, it is only to keep the weight gain to a minimum in my speculative variant of the Wildcat fitted with the R-2600-8 engine. Removing the 2x .50 cal with accessories (at 64 lbs each) and 240 rounds (.3 lbs each with disintegrating link) would be 200 lbs. This would leave a total of 1200 rounds, or 300 for per remaining gun, still a useful amount?

 

[Navalwarrior]

At the Livermore airport there was a rather strange looking carbon fiber prop set built for a P-51 racer.
I help a little with grunt labor moving things around in the fabrication.
The design was tested by NASA in the South SF Bay facility, around 1990 if I remember right.
However, the bolt in the root which is moved in or out to Balance the blades there was a note attached to NOT REMOVE this bolt as it lead to the interior of the Form and the outer skins of fiber.
Well, wouldn't you F'n know, the bolts were removed and the blades blew up like a pillow from the pressure of the oil.
It was never taken any further, but according to the builder he told me it could add heaps of speed to the plane.
It was just too costly a project for an individual owned plane to try again...... sad ending. They were beautiful when they were finished.

Reps: Any photos of the prop?

 

[fliger747]

Certainly the F4F had some room for improvement, perhaps even a R2000 could have been fitted yielding something like a "Beer Cat" in general size and form, bubble canopy and all. However development of a new aircraft was the smart way to go given the US available talent in engineering and production. For fans of the sturdy Wildcat, such morphing would have been a welcome event for this hearty soldier/sailor. For the Navy's war, range and toughness were important criteria and growth in aircraft size were inevitable. Availability of the superb R2800 probably turned design in a direction to optimize an aircraft fitted with that engine.

 

[Shortround6]

The R-2000 was late, it was never developed to be a combat engine and it may have "suffered" from using a supercharger too close to the supercharger in the R-1830.

It is heavier than the R-1830 and only offers any real advantage in HP at very low altitudes

While 1350hp (early models) to 1450hp helped get heavily loaded C-54s off of runways they aren't going to do much for the WIldcat.

the 1350hp engine only held 1350hp to 2000ft in low gear using 2700rpm. It would hold 1100hp at 2550rpm to 7000ft. The engine in the Wildcat would hold 1100hp to 3500ft with the auxiliary stage in neutral and turing 2550rpm and not the 2700rom of take-off. With the auxiliary supercharger in low gear it would give 1050hp at 11,000ft at 2550rpm.
The R-2000 would give 1000hp at 14,000ft at 2550 rpm, the R-1830 would give 1000hp at 19,000ft in high gear at 2550rpm

The later 1450hp R-2000 engines would only hold to 1450hp to 1000ft (some models 1500ft?) and gave 1200hp at 5000ft in low gear at 2550rpm and 1100hp at 14500ft in high gear.

The extra take-off power never translated into a proportional increase in power at altitude. Since the engine as a single stage two speed engine was almost identical in weight to the two stage R-1830 ( you would save the intercoolers) you don't really get much.

 

[Zipper730]

If you put a V-1710 with two-stage supercharging, or a V-1650-3/7 you'd probably see some growth

 

[Barrett]

It's certainly true that FM-2s were exclusive to escort carriers but both Hellcats and Corsairs operated from CVEs with routine safety. Would have to check but perhaps the latter more often went aboard the larger "jeeps" converted from oilers (Sangamons, for instance) rather than those based on merchant hulls. Anyway, the XF4F-8 evolved into "The Wilder Wildcat" which is the hands-down, slam-dunk winner among US piston fighters for victory-loss ratio (around 32-1, I computed the numbers quite awhile back.) That was partly due to the CVE mission, and their fighters most often engaged relatively small numbers of bombers/attack aircraft.

Sidebar: the four-gun FM-2 armament was of course a regression to the F4F-3 battery, as the six-gun -4 was partly/largely due to a UK request. Coupled with the wing-fold mechanism, the airframe gained c. 500 lbs with no commensurate increase in power. In comparing total victories credited (includes probables-damaged) v. destroyed, I found almost no difference between FM-2s and the six-gun machines. However, in the ETO/MTO the six-gun P51D only gained 10% in lethality with a 50% increase in firepower over the B/C models. Looks as if four .50s was the optimum fighter armament of the war!

 

[GreenKnight121]

It's certainly true that FM-2s were exclusive to escort carriers but both Hellcats and Corsairs operated from CVEs with routine safety. Would have to check but perhaps the latter more often went aboard the larger "jeeps" converted from oilers (Sangamons, for instance) rather than those based on merchant hulls.

Certainly not the smaller CVEs converted from the MARCOM type C-3 cargo/cargo-liner hull (Charger, Bogue, Prince William classes, 492'-496' long overall) or the Casablanca class (based on the C-3, but moderately redesigned for carrier use, 512' long) - but the Commencement Bay class (purpose-built [557' oa]), which were roughly based on the MARCOM T-3 tanker hull of the Sangamons [553' oa] and which began entering service in November 1944, certainly operated Corsairs - both in WW2 and in the Korean war!

 

[ThomasP]

Most of the USN CVEs operated VC (Composite) air groups, with a mix of fighter aircraft and attack aircraft. All of the major classes of CVE (Bogue, Casablanca, Sangamon, Commencement Bay) operated FM-2s or F6Fs at one time or another. All the major classes operated TBFs at one time or another also. RN Ameer class (modified Bogue class) and USN Commencement Bay classes operated F4Us at one time or another. The mid-war VC was usually some variant of Wildcat plus SBDs and/or TBFs. Late-war VCs sometimes had their Wildcat variant replaced with F6Fs and/or F4Us.

 

[Ivan1GFP]

The reversion to 4x .50mg was NOT to reduce weight, or any reason other than to increase firing time!

The F4F-3 had the 4-gun armament, with 450 rounds per gun (1,800 rounds total). The F4F-4 went to a 6-gun armament, with only 240 rounds per gun (1,440 rounds total) - which also reduced firing duration from ~34 seconds (gun fire rate ~800rpm) to 18 seconds.

While this armament hit 50% harder, it lasted only 53% as long, and was strongly disliked by many pilots. A work-around was provided where the pilot could disable the outer 2 guns until the inner 4 were out of ammo, then switch to the outers, but this was a poor fix at best.

The FM-1 & FM-2 reverted to the 4-gun 450rpg fit - so you need to figure the actual ammo weights with 4 guns and with 6.

The AN/M2 fitted in aircraft weighed 61 lb (28 kg) each complete (no ammo).
So the gun weights were 244 lb for the 4-gun and 366 lb for the 60gun, but the 4-gun had 1,800 rounds (plus connecting links) while the 6-gun had only 1,440 rounds (with links).

Hello GreenKnight121,
Here is what I have collected for weight information for various models of the Wildcat.
There actually is a small (very small) reduction in weight in going from 6 gun to 4 gun armament.

- Ivan.

 

[fliger747]

If one looks at the difference between the first and last Spitfire, or the Emil vis Kurfurst 109, sure more incremental improvements could have been made. That the F6F and F4U were successful fighters made such development necessary. The new and improved Wildcat was the Bearcat...

Certainly the turtle deck could have been cut down for a bubble canopy, the wings lightened with breakaway wingtips ala F8F, aerodynamics cleaned up, detail structural improvements. Time and energy expended in developing a higher HP power plant tailored for USN requirements and whatnot. The biggest problem with such efforts is combat radius. More power might lug around more external fuel etc.

Development of the F8F was probably a better route.

 

[Shortround6]

Part of the problem is the powerplant.

Trying to stuff an R-2600 into the F4F was a bit much, possible but not really practical?

Any development of a hot rod R-1830 or R-1820 might have been at the expense of the C series R-2800 or the R-4360 for Pratt and at the expense of the R-2600 BB or R-3350 for Wright.
How important is an "improved" F4F vs delaying the 1900hp R-2600 or the B-29 program?

Both small engines did get trickle down improvements form the big engines but except for the FM-2 it was too late to "improve" the F4F and in anycase the improved cylinders and construction didn't translate into higher power at altitude (little or no changes made to superchargers?)

going from 1200hp take-off engines to 1350hp take off engines wasn't really going to change the combat capability that much. Getting several hundred HP more at 15-20,000ft was really going to take a lot of development work.

 

[fliger747]

The S2 Tracker with the R1820 got as much as 1525 HP out of this engine, which showed that there was enough development potential in the engine to make a significant difference. Most of the fighters that lasted the whole war depended on a constant significant engine upgrade.

Priorities?

 

[Shortround6]

The 1525hp version didn't show up until well after the war (1947?) and required either 115/145 fuel or water injection.
This was a "developed" version of the engine in the FM-2 and that engine shared only the bore and stroke with the R-1820s used in the early Martlets.
The 1300/1350hp engine used in the FM-2 used a different crankcase, different crankshaft, different rods, different cylinders (which used a different number of bolts to hold them to the crankcase) with a different method of finning, different heads and so on.

Wright did manage to get 1425hp out of the engine using 100/130 fuel but that wasn't until 1944/45.
these are all take-off ratings, power at altitude dropped quite a bit as Wright was not building high capacity superchargers to match. By late war or post war the R-1820 was a heavy fixed wing powerplant (like the tracker and it's cousins ) or a helicopter powerplant. Nobody was planning on using the R-1820 in combat planes with only few exceptions.

even this

used the 1350hp version although one prototype was fitted with the 1425hp version. The Jet engine in the tail provided altitude performance.

The likelihood of high performance Wright R-1820s in the middle of WW II is pretty slim. It was more than just a matter of priorities, although that factored in.
It was a matter of developing new materials and new manufacturing techniques to make engines strong enough to stand up to the power and/or providing enough fin area for cooling to prevent the engine from melting (or developing hot spots leading to detonation)

from another thread.

the captions aren't quite right. But the cylinder on the right (introduced in late 1942?) has sheet metal fins pressed into groves cut in the cylinder outer walls instead of fins cut from the solid cylinder by lathes or even an aluminum set of fins shrunk onto a steel barrel.

 

[fliger747]

The C version of the R2800's incorporated many of these improvements, especially in respect to cylinder finning and forging. War production left a lot of projects in the roundtuit box. With engineering time and effort applies, perhaps engine improvements could have been effected, however with the move to the R2800 and a bigger airframes, USN didn't have this as a big priority. War production is about smart priorities.

Ship wise, somewhat standard power plants were developed on a HP/shaft basis and a big part in initial design was selecting the right combination of shafts and total HP to fit the design goals.

To reiterate, the Wildcat could have been improved further incrementally, but further leaps were better accomplished by moving beyond a 1930's design.

 

[Dana Bell]

While it's possible the Wildcat had some growth potential, it's clear the aircraft lacked enough potential to be worth the expense in production costs and delays. The FM was already a fine second-string fighter, and nothing BuAer, Grumman, or General Motors could do would ever make it a first-line fighter again. Remember that Grumman toyed with the R-2600-engined F4F in 1938 and realized they'd need to switch to a larger aircraft (which eventually became the F6F) to accommodate the larger engine.

BuAer was very clear in their opinion. In spring 1944 BuAer notified the Pacific Fleet that the F6F Hellcat had reached the limits of its growth potential. If Hellcat development had reached the end, what more could be expected of the Wildcat...

Cheers,



Dana

 

[gjs238]

BuAer was very clear in their opinion. In spring 1944 BuAer notified the Pacific Fleet that the F6F Hellcat had reached the limits of its growth potential. If Hellcat development had reached the end, what more could be expected of the Wildcat...

Interesting...
I was under the impression that F6F improvements were held back to maximize production and as a nod to the F4U - and that had there been no F4U, we would have seen more improvements to the F6F.