F8F Bearcat rate of climb (1 Viewer)

[Neil Stirling]

Question: Did the Bearcat actually climb to 10,000ft, therefore passing through 9,209ft or did it climb to 10,790ft?

Cleveland Airport is 791 ft above sea level, this link seems to indicate a time to climb to 10,000ft http://www.ww2aircraft.net/forum/av...s-grumman-f8f-bearcat-33022-5.html#post911193

Neil.

 

[davparlr]

I have to level the playing field here before everybody gets googly eyed over the F8F. There are some of points I need to make.

1. The Navy, and everybody else, loves to compare its late model prop planes, F8F-1/2, F4U-4/5, to the P-51B/D. However, the P-51B/D were operational at the end of 1943 when they were desperately needed in the war, not in mid-1945 when the war was basically over. The Navy planes were about a generation and a half past the P-51B/D. By mid-1945, the AAF was pretty well washing its hands of propeller driven fighters having cancelled the powerful and impressively performing P-72. Only the P/F-82 continued in development, mainly due to its long range and all weather potential. The AF was only interested in jet fighters. The Navy, on the other hand, leery of the weak jet engines available, needed to keep their prop fighters operational for another four plus years when jet performance and carrier designs helped make carrier jets viable (although their performance was way below the performance required to fight the next air-air war, so they basically set it out). The AF had zero interest in any performance records for prop aircraft. Jets, yes.

2. I noticed the famous flight to 10k ft. in 90 seconds for the F8F was made in November. It would be interesting to know what ambient temperature was. Also, there were several comments about the record being held until the F-16. Ridiculous, the T-38 set a record climb to 40k in 100 seconds in 1962, the F4 beat that in one month, both well before the advent of the F-16.

3. The contemporary to the Navy props was the P-51H, something the Navy never seemed to compare their late fighters to.

4. The P-51s used in most comparisons seem to be lower performance ones using 67" boost instead of the 72-75" boost authorized post May, 1944. Also, they tend to use data with heavy loads of fuel which it is capable of carrying. This tends to not be a factor in comparisons to Navy aircraft as they also tend to carry a lot of fuel.

So here is my comparisons of the P-51B (selected because I have flt test data, its armament is similar to the F8F, and it performs a bit better than the D), the P-51H, F8F-1 (the -2 did not become operational until 1948 ). Data will be airspeed in mph, and climb in ft/min for each altitude level. P-51B will be at 75" boost tested.
150 Grade Fuel



SL
P-51B 386 4420
P-51H 413 5120
F8F 382 4600

5k
P-51B 410 4420
p-51H 434 4280
F8F 410 4000

10k
P-51B 420 3900
P-51H 445 3600
F8F 400 3300

15k
P-51B 428 3820
P-51H 440 3650
F8F 405 3295

20k
P-51B 442 3200
P-51H 463 3100
F8F 420 2600

25k
P-51B 440 2400
P-51H 466 2350
F8F 420 2000

30k
P-51B 430 1700
P-51H 448 1700
F8F 410 1250


So, when the F8F-1 is compared to contemporary powered P-51B or the contemporary P-51H it does not seem to be overly impressive, a good as a performer as it is.

 

[GregP]

I think you're comparing an F8F-1 at Military power (perhaps even Normal power?) and with racks mounted with a clean P-51 at WER power. All of us who regularly see the Bearcat and P-51 fly KNOW which one is hotter, but we still love the Mustang.

Again this weekend, Steve Hinton was not there. He was busy doing a first flight on a newly restored F7F Tigercat. I asked another Bearcat pilot and he said the F8F-2 was around 4,500 fpm at sea level clean, at Military power and had never seen the specs for a WER climb but had done one from a standing start and had easily seen 5,300+ fpm off the runway. He was a normal peacetime weight ... probably a bit lighter than a wartime loadout.

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.

 

[davparlr]

I think you're comparing an F8F-1 at Military power (perhaps even Normal power?) and with racks mounted with a clean P-51 at WER power. All of us who regularly see the Bearcat and P-51 fly KNOW which one is hotter, but we still love the Mustang.

You may be right but the chart I used, which is the same as the F8F-1 charts above, indicate that power used is "Combat" (which also shows the F8F-1 combat power as 2380 hp at SL, Mil power is shown as 2100 hp at 3400'). I did note that this was with racks installed and it shows a correction to a "clean aircraft" was airspeed of 394 mph at SL and a max speed of 434 mph at 19.8k ft. So an eyeballing correction to the chart is below. This could possibly affect climb but insignificantly so.


SL
P-51B 386 4420
P-51H 413 5120
F8F-1 394 4600

5k
P-51B 410 4420
p-51H 434 4280
F8F 422 4000

10k
P-51B 420 3900
P-51H 445 3600
F8F 412 3300

15k
P-51B 428 3820
P-51H 440 3650
F8F 418 3295

20k
P-51B 442 3200
P-51H 463 3100
F8F 434 2600

25k
P-51B 440 2400
P-51H 466 2350
F8F 433 2000

30k
P-51B 430 1700
P-51H 448 1700
F8F 424 1250

I suspect that it is really rare for these planes to be flown at WEP. I suspect that none of the flying P-51Bs have been flown at 75" boost, which was approved in WWII. And how many P-51Hs are even flying, much less at 90" boost?

I still don't think the F8F-1 was significantly better than the P-51B in climb and airspeed at the end of the war and certainly not better than the P-51H (whose numbers above are conservative).

 

[GregP]

It may not have been better in speed right at the end of the war, but was all over it in climb, acceleration, and was better in roll. The F8F can be airborne and quite a way off when the P-51 is just lifting off. When you see them fly side by side, the F8F is a better performer.

Now the F8F is about a 6.3-g fighter at combat weight while the P-51 is an 8-g fighter at 8,000 pounds. But if you load the P-51 to 10,000 pounds as it was on many missions, it is a 6.4-g airplane. I love them both but if I had to get into a fight in one or the other, I'd take an F8F any day based on handling, acceleration, and general maneuverability.

 

[CORSNING]

I agree with Greg, unless the battle is more than 500 mls. from home......I'm just saying, That was the reason the Mustangs Allison/Merlin were so valuable.

 

[GregP]

Yah, long range requirement? P-51 any day, unless you'd go for a P-82 ...

 

[davparlr]

you see them fly side by side, the F8F is a better performer.

I'd take an F8F any day based on handling, acceleration, and general maneuverability.

Hi, Greg,
I have a sneaky suspicion that all the comparisons you have been exposed to were P-51Ds to F8F-2s, a 1944 aircraft to a 1948 aircraft, a couple of generations apart. I think that if you compared a 2200+ hp, 9200 lb P-51H to a 2300 hp, 9200 lb F8F-1, both 1945 aircraft, you would find that the much cleaner P-51H (which means it uses less power at any given airspeed) could out accelerate the F8F-1 at any given airspeed although at lower airspeeds it would be very close. I also think the climbing ability of the P-51H is rather impressive as is the F8F-1. And with a 30 mph airspeed advantage above 10k, the P-51H has all the offensive advantages there.

I just went through the AF Museum at W-P. Do you guys do any work with them? They are upgrading but I missed some aircraft like the P-59, which you are trying to get off the ground, and no P-80A (they may not exist), but did have a P-80C. Also, I did not see the only aircraft responsible for a victory in a Soviet-West Cold War confrontation, the historically great and under appreciated C-54 (and their crews and ops people). I could have missed some things because it is so big and I had limited time (wife was at daughter's home and I had the car). Museum operation has been impacted by sequester.

 

[GregP]

No P-51H could outclimb any Bearcat. The P-51H was faster and longer-ranged, but not as maneuverable. Pure fighter? The Bearcat has no equal that I am aware of in the piston family. Of course, they didn't make very many, either. Everyone was gaga over jets. Sitting in one makes me want to commit aviation in it.

We have done some work with many other museums, but not specifically Wright-Patersion as far as I know. They DO have a nice collection. Right now, we're missing two of ours. The Zero is in Japan and the P-47 is in Idaho. Hopefully both back in a few months.

Come out and see us again sometime, Dave.

 

[Shortround6]

No P-51H could outclimb any Bearcat. The P-51H was faster and longer-ranged, but not as maneuverable. Pure fighter? .

Out climb?

http://www.wwiiaircraftperformance.org/mustang/p-51h-booklet-pg15.jpg

http://www.wwiiaircraftperformance.org/mustang/F-51H_Mustang_SAC_-_22_March_1949.pdf

Granted you may have to thrash the P-51H harder to get the performance and I doubt anybody outside of Reno is going to run a modern P-51H (if one is flying) at anywhere near 90in MAP.

Perhaps the Bearcat rolled better?
The Bearcat has about 3% more wing area. (thats gross, net wing area may be different). weights clean are within a few hundred pounds of each other, Mustang may be lighter, it may depend on WHICH F8F but I don't know.
Turn is not 100% dependent on wing loading but it seems the two are very close.

I doubt the "H" could out climb the Bearcat except in rare circumstances but the "H" is a much closer performer to the Bearcat (-1 model) than the "D".

 

[davparlr]

I doubt anybody outside of Reno is going to run a modern P-51H (if one is flying) at anywhere near 90in MAP.

I am sure you are correct.

http://www.wwiiaircraftperformance.org/mustang/F-51H_Mustang_SAC_-_22_March_1949.pdf


I doubt the "H" could out climb the Bearcat except in rare circumstances but the "H" is a much closer performer to the Bearcat (-1 model) than the "D".

I don't think your doubt here is supported by the referenced sites in this thread. Below is the data taken form krieghund post #6 for the F8F-1 and your reference above for the P-51H. Reference weight for the F8F-1 is 9360 lbs and is 9430 lbs for the P-51H. First number is rate of climb in ft/min for the F8F-1 and second number is the value for the P-51H

SL 4780 5000

5k 4000 5000

10k 3300 4250

15k 3280 3850

20k 2600 3600

25k 1950 2800

30k 1250 2000

Since there will probably never be a fly-off of these two planes all we have is opinion and some data. The data here seems to show the P-51H rather easily outclimbs the F8F-1.

 

[davparlr]

Come out and see us again sometime, Dave.

I had a great time! You bet I'll be back. I think I owe you guys a lunch.

 

[GregP]

In the experience of the active wearbirds pilots I know, including some hall of fame pilots, no stock Mustang ever outclimbed a Bearcat if both were running correctly and were actually trying.

The Reno guys aren't about climb anyway, they are about speed, but Rare Bear DID set a world time to climb record that still stands. A stock P-51H doesn't exist anymore AFAIK, but the remaining ones still won't out climb a stock Bearcat. The only two Mustangs I am aware of that might are Voodoo and Strega, and both churn out more than 3,700 HP from engines that aren't really Merlins anymore.

If they use Nitrous Oxide in Rare Bear (not since Rod Lweis has owned it), it will produce about 4,500 HP. Without Nitrous it makes about 4,000 HP and is pretty much untouchable unless you have a 3rd or higher generation jet fighter designed for climb rate. But a stock Mustang? Nahhh ....

 

[wuzak]

In the experience of the active wearbirds pilots I know, including some hall of fame pilots, no stock Mustang ever outclimbed a Bearcat if both were running correctly and were actually trying.

The Reno guys aren't about climb anyway, they are about speed, but Rare Bear DID set a world time to climb record that still stands. A stock P-51H doesn't exist anymore AFAIK, but the remaining ones still won't out climb a stock Bearcat. The only two Mustangs I am aware of that might are Voodoo and Strega, and both churn out more than 3,700 HP from engines that aren't really Merlins anymore.

If they use Nitrous Oxide in Rare Bear (not since Rod Lweis has owned it), it will produce about 4,500 HP. Without Nitrous it makes about 4,000 HP and is pretty much untouchable unless you have a 3rd or higher generation jet fighter designed for climb rate. But a stock Mustang? Nahhh ....

Isn't the comparison supposed to be between a stock P-51H and a stock F8F-1?

FWIW, I believe the Spitfire XIV/21 or Spiteful XIV could beat the P-51H to 20,000ft, even if their initial climb rates were lower.

 

[GregP]

Hi Wuzak,

I believe I said STOCK Bearcat and Mustang when talking about comparisons.

I said the Reno racers had more HP and better performance, but stock versus stock, the Bearcat was ALL OVER any Mustang in roll, climb, and turn. Pretty darned close in speed.

 

[Jabberwocky]

Just for gits and shiggles, Hornet F.1 w Merlin 130/131 at + 20 lbs boost (1960 hp at 4000 ft/1840 hp at 17,000 ft) and 15600 lbs weight, July 1946 tests from http://www.spitfireperformance.com/spit14climbchart.jpg

0 ft: 5425 ft.min (~300 ft.min better than P-51H)
5,000 ft: 5425 ft.min (~950 ft.min better)
10,000 ft: 4,700 ft.min (1100 ft.min better) - 10,000 ft in less than 2 minutes
15,000 ft: 4,700 ft.min (1150 ft.min better)
20,000 ft: 4,400 ft.min (1300 ft.min better) - 20,000 ft
25,000 ft: 3,500 ft.min (1150 ft.min better)
30,000 ft: 2,500 ft.min (800 ft.min better)

In addition, the Merlin 130/131 was cleared for +25 lbs boost with 150 grade fuel, giving 2,070 hp, so that's not even the best RoC that a Hornet could pull. 8)

 

[fastmongrel]

Is climb rate a simple power versus weight equation or do other factors come into it.

 

[Shortround6]

A few factors but the main thing is figuring out how much power you have AFTER subtracting the power needed to fly level at the minimum drag speed or climbing speed. For a P-51H with bomb and rocket racks this seems to be 175mph at sea level. What ever power is needed to maintain level flight at this speed ( and this provides the lift to keep the plane in the air) is subtracted from the total power and remaining power is the power available for climb.
Of course the power needed for the Mustang to fly at 175mph has to include the power needed to overcome the drag of the fully open (or mostly open) radiator door,, just like other planes when climbing have cowl and oil cooler doors/flaps open more max cooling so the drag is higher than the drag if the plane was simply cruising at 175mph.

 

[Shortround6]

but stock versus stock, the Bearcat was ALL OVER any Mustang in roll, climb, and turn. Pretty darned close in speed.

Which Bearcat?

The -1 or the -2?

the -2 was about 1000lbs heavier in max clean condition but it's "E" series engine ( about 200lbs heavier) offered an extra 150 HP for take-off dry and much better altitude performance. It also used hydraulic drive for the supercharger and no shifting of gears. Power with water injection ???

part of the difference in engine power (supercharger) can be seen by the max speed of the -1 being 421mph at 19,700ft and the -2 going 447mph at 28,000ft.

The Bearcats ( either of them) would be all over the P-51D but the "H" cuts into the margin quite a bit.

Of course the difference in the P-51H performance rather depends on if it was using 67in, 75 in, 80 in or 90 in of MAP.

 

[davparlr]

Is climb rate a simple power versus weight equation or do other factors come into it.

I am not an aero guy but I know enough to be dangerous so here goes. Power-to-weight ratio is certainly important, however other factors come into play such as airfoil design (airfoils have different lift-drag ratios,L/D, the higher the number the better). Another factor is aircraft cleanliness (aerodynamic efficiency). As already explained by Shortround6 above, climbing ability is not power-to-weight but rather excess power-to-weight (e.g., an aircraft flying at max airspeed cannot climb at that airspeed. It may have great power-to-weight but has no excess power to climb.) The less power required to maintain an airspeed, the more power available to climb. I believe this aids the P-51 in its climbing ability relative to its moderate power-to-weight ratio. The P-51H has a SL max speed of 413 mph, the F8F-1 can do 386 mph with a bit more power. This indicates the P-51H is a cleaner aircraft. If both were at SL (+100 ft ) and were flying side by side at 386 mph and had to climb, say for a hill, the F8F would have to lose airspeed in doing so, it is using all of its power to maintain airspeed. The P-51 could maintain 386 mph and climb, because it has excess power. So at SL and 386 mph, the P-51 could out climb the F8F. One could calculate the excess hp available to the P-51 at 386 mph by knowing the power required at 413 mph (about 2200 hp) and applying the drag formula. Since drag increases by the square of the airspeed this hp number would be greater than you would expect (and hp is a cube!!??!). Anyway, I don't want to do it.