Fulmar II versus F4F-4 under 10,000 ft.

[RCAFson]

This is a comparison of the Fulmar II and F4F-4, under 10,000ft. Obviously above that altitude the Merlin 30 rapidly runs out of power, but since much of WW2 naval air combat took place under 10,000ft (which was the FAA's rational for low altitude rated engines) it is useful to compare these two aircraft under 10,000 ft. I think the comparison helps to place the Fulmar and Fulmar II's performance in perspective when we realize just how well the F4F-4 did given its rather marginal advantage over the Fulmar under 10,000ft.


Power:
normal: ~1100/1090hp to aprox 11000ft
WEP: 1360hp at 6000ft / 1200hp at 1800ft, 1135hp at 3500 ft, 1150 hp at 11,500ft

weight: 9672lb / 7975lb
wing area: 342sq ft / 260 sq ft
wing loading: 28.3lb / 30.7lb
Fuel: 190usgals / 144usgals
8 x .303, 1000rpg / 6 x .5", 240 rpg

climb:
Initial:
Normal:1538** / 1690 fpm
Combat: ???? / 1850 fpm
normal time to:
5000ft: 3.25min / 3.25min*
10000ft: 7.17min / 6.5min
15000ft: 12min / 10.6min*
20000ft: 20min / 14.7min
combat climb to:
5000ft: ???? / 2.9min
10000ft: ???? / 5.9min
15000ft: ???? / 9.1min*
20000ft: ???? / 12.7min
Power:
WEP: 1360hp at 6000ft / 1200hp at 1800ft
1 hr limit: ~1200/1090hp (aprox under 10000ft)

Normal Max speed
SL: ???? / 274
1750ft: 264 / 280mph*
5000ft: 265 / 283*
7250ft: 272 / 290*
9600ft 265 / 296*

Combat max speed:
SL: ???? / ????
1750ft: ???? / ????
5000ft: ???? / ????
9600ft: ???? / ????



* interpolated
** based upon time to 5000ft
data from WWII Aircraft Performance especially:
http://www.wwiiaircraftperformance.org/f4f/f4f-4-02135-performance.jpg
and various sources for the Fulmar, including wikipedia, Warpaint 41, and data from British Carrier Aviation. Data on the Fulmar/Fulmar II is often contradictory and I had to make some choices between the data sets, especially for max weight. Also it appears that the Fulmar II had a tropical filter in some models and this caused a reduction in max speed, which might account for the variation in Fulmar II performance stats.

Edit: the fuel consumption for the Merlin 30 goes from 105 igals/hr at 9.75lb boost/2850 rpm to 130 igal/hr at 12lb boost/3000rpm, so this suggests 1100hp and 1360 hp.

 

[Greyman]

Comparing the speed and climb curves here http://www.wwiiaircraftperformance.org/f4f/f4f-4.pdf with Fulmar II flight test data I have, it's not even close. The Wildcat is far superior.

Actually the Wildcat vs the Firefly or Sea Hurricane appears to be a more even matchup.

 

[RCAFson]

Comparing the speed and climb curves here http://www.wwiiaircraftperformance.org/f4f/f4f-4.pdf with Fulmar II flight test data I have, it's not even close. The Wildcat is far superior.

Actually the Wildcat vs the Firefly or Sea Hurricane appears to be a more even matchup.

OK, but compare the above with:
http://www.wwiiaircraftperformance.org/f4f/f4f-4-4058-performance.jpg (at 7370lbs)
and
http://www.wwiiaircraftperformance.org/f4f/f4f-4-02135-performance.jpg (7933lbs)
and
http://www.wwiiaircraftperformance.org/f4f/f4f-4-detail-specification.pdf
and note how the detail specification matches the performance of the 1st two references.

I just don't see how there can be such a wide variation between actual aircraft and the Standard Aircraft Characteristics (SAC), and pilot comments seem to invalidate the SAC figures.

 

[RCAFson]

sorry DP.

 

[Greyman]

I'm not sure how to get speed figures in the first two .jpgs

The speed in the .pdf roughly matches up with the .pdf I linked and while slightly slower, still crushes the Fulmar II.

 

[RCAFson]

I'm not sure how to get speed figures in the first two .jpgs

The speed in the .pdf roughly matches up with the .pdf I linked and while slightly slower, still crushes the Fulmar II.

Remember that this is a comparison below 10,000 ft.

The climb rate figures seem to match the Detailed Specifications (DS) figures and at critical altitude:

Max speed
http://www.wwiiaircraftperformance.org/f4f/f4f-4-4058-performance.jpg (at 7370lbs) = 318 mph at 19400 ft
and
http://www.wwiiaircraftperformance.org/f4f/f4f-4-02135-performance.jpg (7933lbs = 316 mph 17200 ft

DS = 318 at 7426 lb and 316 mph at 7970lb. ( http://www.wwiiaircraftperformance.org/f4f/f4f-4-detail-specification.pdf )

The Detailed Specifications (DS) were based upon an actual aircraft's performance (see the bottom of page 5) and at 4600ft the DS states 283mph where the SAC states 294 mph at 5000ft, both with normal power. The SAC figures cannot be met by four different actual aircraft and again seem hopelessly optimistic.

 

[Greyman]

Well, the 17,000 and 19,000 foot figures don't really help us.. that's why I like the http://www.wwiiaircraftperformance.org/f4f/f4f-4.pdf document. While not a real flight test report it still gives a good idea what the F4F can do at X altitude.

Still, with 283 mph at 4,600 feet - the F4F has over 20 mph on the Fulmar II at the same height.

 

[RCAFson]

Still, with 283 mph at 4,600 feet - the F4F has over 20 mph on the Fulmar II at the same height.

That's true but the F4F-4 normal power is about 1090 hp at 4600ft, and WEP = 1150 are about another 5.5%, OTOH the Fulmar probably goes from about 1100 (9.75 lb boost at 2850rpm to 12lb at 3000rpm) to 1360hp or about a 23% gain. I would guess that with both aircraft at WEP and 5000ft, that the speeds would be nearly identical, as would the climb rates.

 

[Greyman]

For the Fulmar II (9,980 lb) I have:

249.5 mph at 5,000 feet (+9¾ boost, 2,960 rpm)
263.0 mph at 5,000 feet (+12½ boost, 2,960 rpm)

 

[RCAFson]

OK, what is the source?

 

[Greyman]

A&AEE Report from Boscombe Down.

Exact same type of report that the boys at wwiiaircraftperformance.org have for all of the RAF aircraft (and some US aircraft).

 

[RCAFson]

Cool. Does it have the climb rate?

I wonder if you could post the performance curves somewhere?

Also. is that with the tropical cowling?

 

[Greyman]

Can't really post anything at the moment unfortunately. A graph can be drawn faily easily for climb rate though since it just involves straight lines.

point #1 - 1,415 feet per minute at 1,000 feet
point #2 - 1,440 feet per minute at 7,200 feet
point #3 - 200 feet per minute at 23,000 feet

Fulmar II (9,980 lb) +9¾ boost 2,850 rpm

 

[Greyman]

Also, for the sake of comparison, don't forget many Fulmar II aircraft had four Browning .50s with 370 rounds per gun instead of the .303s...

EDIT: actually conflicting data here. Another (much more in-depth) report says 415 rounds for the inboard guns and 450 rounds for the outboard.

 

[RCAFson]

Can't really post anything at the moment unfortunately. A graph can be drawn faily easily for climb rate though since it just involves straight lines.

point #1 - 1,415 feet per minute at 1,000 feet
point #2 - 1,440 feet per minute at 7,200 feet
point #3 - 200 feet per minute at 23,000 feet

Fulmar II (9,980 lb) +9¾ boost 2,850 rpm

Fantastic!!

So it's fair to say that climb performance at the combat rating would have been substantially better given that WEP gives considerably more power, about 23% more up to 6000ft by my reckoning.

Do you have max speed at normal and WEP?

Thanks for this info, BTW.

 

[Greyman]

Again, you can draw lines with these to get a good idea as to what's on the tests. In other words, you can basically draw a line from the critical alt point through the low point I list down to sea level.

+9¾ boost, 2,960 rpm
246 at 4,000
264 at 9,600 (critical alt)

+12½ boost, 2,960 rpm
260 at 4,000
268 at 6,600 (critical alt)

Above the critical altitudes it starts curving back similar to all Merlins.

I don't think the full boost climb would be too much better. Looking at the graphs I would estimate around 1,700 ish.
Could be wrong though... just extrapolating.


EDIT: actually I guess your +23% would be right around the mark (1,740 to 1,771 feet per minute)

 

[RCAFson]

Sorry to ask again, but do you know if this performance was with the tropical cowling?

 

[Greyman]

Temperate cowling. Tropical cowling without air cleaner elements fitted costs roughly 7 mph, and the tropical cowling with cleaner elements subtracts about 8 mph.

 

[RCAFson]

OK thanks. So we can see that, with WEP, the F4F-4 was about 25 to 35 mph faster than the Fulmar II from SL to 10000ft, but the Fulmar probably had a slighter better climb rate up to 10k ft:

Fulmar II/ F4F-4 combat climb to:
5000ft 2.85* / 2.9min
10000ft 5.8* / 5.9min
15000ft ???? / 9.1min*
20000ft ???? / 14.7min

*estimates

 

[davebender]

Pretty bad for a CV based fighter aircraft. After attacking an enemy torpedo bomber at 300 feet you are out of the fight. You are also dead meat for any enemy aircraft with a bit of an altitude advantage.