F8F Bearcat rate of climb

[Neil Stirling]

Thanks Fastmongrel, Krieghund, and Mike! Appreciate it.

I see Neil used 58" for the Bearcat and estimated Hornet performance at 25 lbs boost (80" Hg). Considering they regularly ran the R-2800 on test benches at 150 inches (59 lbs boost), maybe 58" is a bit conservative. 58" was military power and 70" was WER. If you're going to use full boost (the 5 minute rating) on the Merlin 130 / 131, it makes sense to use full boost on the oither planes, too ... or restrict the Merlins to "Normal power."

That's why I tend to discount reports where one plane is being operated at the limit while an ostensible competitor is being restricted to less than full power. I've seen it happen from all sides. Anyway, there are several aircraft with very good climb, maneuverability, and acceleration. The Bearcat and the Hornet / Sea Hornet are certainly two of them.

Greg if you can provide Bearcat figures using 70"hg please do, or put together a spread sheet chart showing your estimations.

Although the charts are headed 1946 fighters all the aircraft had flown by April 1945.
The F8F-1 was cleared (When?) for 70"hg, however, I cant find reliable performance figures and I am not confident estimating it.
During 1946 or 47 the -4 Corsair (Some not many) was fitted with the 42W engine and this produced around 2,780hp.
The Hornets performance is estimated from performance at +20lbs boost.
All aircraft clean no racks.
Fire Power from Flying Guns World War II by G.Williams and E. Gustin

Bearcat F8F-1 58"hg = 2,400hp Combat, Military 2,100hp http://www.ww2aircraft.net/forum/aviation/f8f-bearcat-rate-climb-37299.html

Neil.

 

[GregP]

Hi Neil,

I've been trying to catch Steve Hinton for 2 - 3 weeks now on Saturday when he is there to ask to see his dash one pilot manual for the F8F, but he's been swamped with tasks. He did say the dash one may not tell the max climb since it is mostly operations. Has great charts for takeoff and typical mission profiles, but may not address WER climb (I asked him as he was leaving to test fly a freshly-restored Tigercat).

Hopefully the dash one DOES address WER climb and I can catch him soon.

You hit the nail on the head ... there is precious little charted data available that is reliable. Sometimes all you have is one number (mostly without altitude or speed) and we all know the speed and climb rate changes with altitude. I've seen a so-called pilot's manual in pdf format, and it gives performance that seems quite low compared with what we see today. Then you read the small print and it says the data were all compiled with full fuel ,full ammo, one 150-gallon centerline drop tank, and bomb racks installed. Removing the tank added something like 13 mph and removing the racks added another 10 mph ... but they never mentioned the effect on climb, and the climb data was a single number. I did notice the climb data were all with tanks and rack and made at Normal Power (2,250 HP) but the engine is actually rated at a WER of 2,500 HP. Also, they didn't give the altitude where the climb rate was measured. Frustrating, to say the least. For instance, I have some data for most of the top Japanese types by altitude, so I can create speed and ROC charts. But the weight and power settings are not specified with the data ... so how good is it? If I did it and posted it, I'd just take flak for it and I simply don't have the other information.

Back to the F8F, I would think that 3,750 fpm climb when carrying full internal fuel, full armament, plus a 150-gallon centerline tanks and bomb racks at 58" MAP would turn into a much better climb rate when clean with partial fuel and using WER of 70" MAP. I know what I have heard from Bearcat pilots, but talk is cheap.

So, I'm trying to find something that is believable as a reference rather than personal experience (I catch a lot of flak in here for relating pilot experience) though I believe Steve as he doesn't inflate things ... he flies a LOT of different warbirds and has no axe to grind. In fact, he sometimes flies things he doesn't like to fly just for the people to see (doesn't think much of a few warbirds that shall remain nameless). Anyway, I'll keep checking and get back to the thread.

By way of example, he was quoted in a magazine as saying the F model P-38 was faster than the J model. I asked him about it one Saturday and he said that while he was quoted correctly, they didn't suppply the context. In reality, the F model is a bit cleaner and is faster at equivalent power and rpm. But the J model has more powerful engines and is a faster aircraft at full power. All he intended to say was that the F was faster when crusing with a J and if both were at the same manifold presure and rpm. Alternately, to fly formation, the J model uses slightly more power than an F model.

I have no dog in this hunt since I like all the great piston fighters ... as well as quite a few jets.

As a matter of curiosity only, I've seen numerous references on the web for the Hornet / Sea Hornet showing 4,000 fpm as the rate of climb, one showing 4,650 fpm, and now the reference from you at over 5,000 fpm. I wonder if the loadout is known for your chart? I'd believe the high climb rate at very light weight (say, 1/3 fuel, no ammo, no survivial gear, pilot and chute in shorts), but not at full capacity ... that is, full internal fuel, full ammunition, full consumables, survival gear, and pilot with gun and parachute and maybe winter clothes.

Much the same can be said for the F8F. You CAN load it down and still get good performance, but you can also lighten it up and get sparkling performance. So, the numbers are pretty useless without other information to go along with them ... for ANY aircraft and many times the other numbers and conditions aren't noted on the charts or in the manuals.

Anyway, nice charts, Neil. Did you use Excel? Maybe add some gridlines?

 

[Neil Stirling]

Hi Greg

The -1 manual is available online, do a Google search you will find it, it is dated 1949 and lists 70"hg with 115/145 octane fuel. The charts Krieghund posted come from June 1945 and I believe represent the use of 100/130 octane.

To say nothing would give me more pleasure would be a exaggeration, however, a document with the date stating the clearance of 70"hg would be a start. As the charts I posted very clearly state 1946 fighters. If this information is forth coming I can re do the Excel chart with grid lines and the P-47M.

BTW I rate the F8F-1 as top dog piston fighter at low altitude when using 70"hg.

Reference the Hornet and 4,000ft/min, it comes from "Flight magazine 45/46" climb to 20,000ft at an average of more than 4,000ft/min (+20lbs boost)

Neil.

 

[RCAFson]

An unmodified production F8F-1 set a 1946 time-to-climb record (after a run of 115 ft/35 m) of 10,000 ft (3,048 m) in 94 seconds (6,383 fpm). The Bearcat held this record for 10 years until it was broken by a modern jet fighter (which still could not match the Bearcat's short takeoff distance).

I really doubt that this record stood for ten years unless it simply wasn't officially challenged. There were lots of jet fighters appearing in the late 1940s and early 1950s that could do considerably better.

 

[GregP]

Yet it did stand for 10 years. That suggests the military wasn't interested in bettering it, but a record is a record.

Just for info, the guys that used to race Strega wanted to try for a new piston engine, propeller-driven world speed record, but the attemnpt would cost more than a race at Reno, so they shelved it. The plane will easily do 540+ mph but the cost is a major factor. They could probably also set a world time to climb record, but that, too, is very expensive. It isn't the setting of the record ... it is paying for all the equipment, the FIA representatives, and other people to be there when you do it to verify the numbers.

 

[CORSNING]

Before I even get started, I'd like to say that I am only interested in the facts. From every thing I have read to date, the facts point to the Bearcat as being the premier climber. However, I have studied both graphs issued by the Bureau of Aeronautics, Navy Dept. and they go like this:

Both A/C clean (no pylons/shackles) and in all up combat condition. Altitude in meters, speed in mph and climb in fpm.

ALTITUDE...F8F-1........F4U-4
S.L...........394/4600...383/4770
.1,000.......415/4220...397/4780
.2,000.......419.3705...411/4800
.3,000.......415/3290...424/4810
.4,000.......410/3275...439/4290
.5,000.......424/3115...445/4340
.6,000.......434/2615...458/3880
.7,000.......434/2220...463/3300
.8,000.......431/1735...446/2650
.9,000.......425/1325...442/2125

Weight......9,334 lbs....12,480 lbs.
W.E.P.......2,400 hp.....2,450 hp.
Power load: 3.889+.....4.49 lbs./hp.
Wing load: 38.25+.....39.51 lbs./sq.ft.

I know the power load figures only apply when the engine is at its maximum output, but looking at both their weights vs. horse power the Bearcat should be dominant.???

Need help on this one guys, Jeff.

 

[wuzak]

Are the altitudes correct? Seems low for max speed for each aircraft - 6-7000ft.

And low for the climb numbers.

I would expect that the F4U-4 would have superior climb as they get to higher altitudes because of the two stage supercharging (F8F-1 is only single stage). The F4U-4's engine would maintain power better, and at 10 or 20,000ft should hold a substantial power advantage.

 

[Shortround6]

Altitude is in meters, not feet.

 

[wuzak]

Altitude is in meters, not feet.

It pays to read things thoroughly! Thanks - that makes more sense.

 

[Shortround6]

I know the power load figures only apply when the engine is at its maximum output, but looking at both their weights vs. horse power the Bearcat should be dominant.???

Need help on this one guys, Jeff.

The Bearcat would be dominant at low level.
The Corsair would have 1800hp Military (not WER) at 23,000ft though.
The Bearcat -1 had 1700hp Military at 16,000ft. It should have between 1400 and 1470hp at 23,000ft?

Knocking off about 280lbs per plane for fuel burned in climb ( quite possible too low) you get a power to weight for the Corsair of 6.7lbs per hp and the Bearcat has 6.2lbs per HP.
The Corsair has the possibility of WEP at that altitude, an extra 200hp or so?
The Bearcat-1 has little (50-75hp?) or no possibility of WEP at 23,000ft. manifold pressure has been dropping since 17,000ft ( OK since 18-19,000ft due to RAM but we are not giving credit for RAM to the Corsair either)there is no spare supercharger capacity or little gain to be had from the water injection.

The engine in the -2 Bearcat is a different story.

 

[Shortround6]

It pays to read things thoroughly! Thanks - that makes more sense.

Read more than one thing wrong myself, no worries.

 

[GregP]

Let's say we disagree and leave it at that.

I, too, read things wrong once in awhile and sympathize. Maybe I did this one, maybe not, but nothing wrong with a late model Corsair of almost any variety. Becasue one plane is better doensn't mean all other are worthless. Even a football team not as good on paper wins sometimes. A good plane with a great pilot will win almost every time.

 

[krieghund]

Most Bearcat owners don't do a WER takeoff and climbout very often.

Naturally, I'll continue to look for the F8F-2 -1 pilot's manual for a reference other than a current pilot.

Greg I posted the FM here since 2007: http://www.ww2aircraft.net/forum/other-mechanical-systems-tech/f8f-bearcat-8251.html#post252299

Here is the engine portions of the manual

 

[GregP]

Seems like it is just what Steve Hinton said ... the dash one doesn't cover a WER climb from ground level.

I'll still look for his manual since most of the pdf manuals I see online are NOT what the real manual says when I read one. Might be the same, might not be ... we'll see.

 

[Neil Stirling]

Before I even get started, I'd like to say that I am only interested in the facts. From every thing I have read to date, the facts point to the Bearcat as being the premier climber. However, I have studied both graphs issued by the Bureau of Aeronautics, Navy Dept. and they go like this:

Both A/C clean (no pylons/shackles) and in all up combat condition. Altitude in meters, speed in mph and climb in fpm.

ALTITUDE...F8F-1........F4U-4
S.L...........394/4600...383/4770
.1,000.......415/4220...397/4780
.2,000.......419.3705...411/4800
.3,000.......415/3290...424/4810
.4,000.......410/3275...439/4290
.5,000.......424/3115...445/4340
.6,000.......434/2615...458/3880
.7,000.......434/2220...463/3300
.8,000.......431/1735...446/2650
.9,000.......425/1325...442/2125

Weight......9,334 lbs....12,480 lbs.
W.E.P.......2,400 hp.....2,450 hp.
Power load: 3.889+.....4.49 lbs./hp.
Wing load: 38.25+.....39.51 lbs./sq.ft.

I know the power load figures only apply when the engine is at its maximum output, but looking at both their weights vs. horse power the Bearcat should be dominant.???

Need help on this one guys, Jeff.

There were 2 types of engine fitted to the F4U-4, the -18W 2,400hp or the 42W 2,750hp, the 42W being fitted to some F4U-4B's from Bu No. 97486 onwards constructed after the 16th of August 1946.

This chart with the 18W http://www.alternatewars.com/SAC/F4U-4_Corsair_ACP_-_1_March_1946.pdf dated 1 March 1946 shows much lower climb performance. This chart http://www.wwiiaircraftperformance.org/f4u/f4u-4.pdf date absent also shows the 18W but does show the use of 115/145 octane fuel and I think matches your figures. Either the second chart represents a re-rating of the -18W after March 1946 or the engine represented was the 42W.

F4U-4 Vought F4U-4 Pilot 's Handbook of flight operation instructions (1944) F4U Corsair Documents Manuals | Aircraft Manuals / Documents.

12,480/2450 = 5.09 lbs/hp

12,480/2750 = 4.54 lbs/hp

Revised F4U-4 performance as of 1st April 1945 within here http://www.ww2aircraft.net/forum/flight-test-data/f4u-performance-report-comparisons-36776.html

Neil.

 

[CORSNING]

Neil,

Thank you for the information and documents.

Jeff

 

[Neil Stirling]

Thanks Jeff,

In order to try and get to the bottom of this I have ordered the 1947 F4U-4 F4U-4B manual.

Neil.

 

[swampyankee]

there's no way it could climb 6000 ft in 90 seconds.

Correct that DCG2U. Go on now.[/QUOTE]

It demonstrated, in a stunt, but nonetheless demonstrated standing start to 10,000 ft in 94 seconds, which is about 6,400 fpm. Toss out ten seconds for ground roll, and the rate of climb is about 7,100 fpm. Even if normal combat weight is 50% higher, which I doubt, this would result in a rate of climb of about about 4,500 fpm.

The manual numbers are, of course, definitive for the weights and conditions given.

 

[spicmart]

Could one build a Fw 190D or Ta 152 using Jumo 213S / DB 603N to match the F8F-2 in performance (overall and/or climb rate)?

 

[GregP]

None of the Fw 190 variants were ever even close to the Bearcat in climb, yet all had very good engines.

The Ta-152 was never a factor but, since it did not even achieve 4,000 feet per minute, I think it would have required quite a horsepower shot to get there. I think you COULD have done so, but not with any of the existing engines. They probably would have needed something in the 2,850 hp range to do it.

Candidates might have been the DB 604, 607, or 610. The DB 604 was a prototype engine only and the DB 607 and 610 were more than 50% heavier than the Ta-152's real engine, so I sort of doubt that was ever going to be a real possibility. The DB 613 had the power, but was almost twice the weight of the Jumo 213. Again, not going to happen.

One possibility for climb improvement would have been for the Germans to go with a better propeller design with more blades, but that might all but eliminate the fuselage-mounted armament as effective guns. They stuck with the 3-blade prop in order to have an effective firing rate for nose guns.

It seems to me that the aircraft would have to be substantially modified to add another 50% to the climb rate, and they only delivered about 43 of them in the real war. A protracted development chasing climb rate might have resulted in none ever flying. Of colurse, they might also have gotten it done, had it been a priority. You can't argue thath the Germans weren't creative ... they WERE. I seriously doubt they'd ever chase a Bearcat's climb rate anyway since none were deployed to Europe in WWII or were even considered for such ... the war in Europe was over before the Bearcat was delivered to the fleet.