Fairly Firefly Mk.I vs Mk.IV

[Zipper730]

I know the Mk.IV had a new radiator and a higher critical altitude engine, but I'm not sure what effect this had on critical altitude precisely (like how high), and speed (yes I have searched but the universe seems to be conspiring to keep me from finding my data ).

I'm also curious about the range of the Mk.IV as it has 46 imperial gallons less, but can fly faster at altitude

 

[parsifal]

Firefly I / FR.I
Two variants of the Mk I Firefly were built; 429 "fighter" "Firefly F Mk I"s, built by Fairey and General A/C, and 376 "fighter/reconnaissance" Firefly "FR Mk I"s (which were fitted with the ASH detection radar. The last 334 Mk Is built were upgraded with the 1,765 hp (1,316 kW) Griffon XII engine. The Mk I was the only subtype to see wartime service before 1945.

The RN was constantly tinkering with the payload options for the firefly. Just limiting the discussion to the wartime variations, The offensive payload was 2000lbs with a 90 gal drop tank. After the war this was increased to 4000lb, 2 x 90 gallon tanks.

Handling and performance trials were first undertaken at Boscombe Down in 1942; by 1944 the Firefly was cleared to use underwing rocket projectiles and by April 1944 tests with a double underwing load of 16 rockets and two 45 gallon (205 l) drop tanks still provided acceptable handling. This was not the final maximum load out, however Further testing with two 90 gallon drop tanks or two 1,000 lb (454 kg) bombs deemed acceptable albeit with "...a small adverse effect on handling..." while "...handling with a single 1,000 lb (454 kg) bomb was unpleasant, but manageable." Performance trials at 11,830 lb (5,366 kg) indicated a maximum speed of 315 mph (508 km/h) at 16,800 ft (5,121 m); a climb to 20,000 ft (6,096 m) took 12.4 minutes, with a maximum climb rate of 2,140 fpm (10.87 m/s) at 3,800 ft (1,158 m), and a service ceiling of 30,100 ft (9,174 m). These are the performance figures often quoted for the Mk I

Firefly Mk Iv
The Mk IV was aerodynamically cleaned up and re-engined with a griffin engine rated at 2330hp

Performance of the F4 subtype can be found here;

Fairey Firefly FR.4

It has a published maximum speed of 367mp @14k, a range of 760 miles,

Im unsure why you would want the performance figures of the Mk IV, since it only had a limited production run and short operational life span. The main post war subtypes were the Mk 5 and Mk 6. The AS Mk V was the last cannon armed version, and represented the pinnacle of RN carrier based strike aircraft using internal combustion engines. Able haul 4000lbs of ordinance, with a range of over 760 miles and a maximum speed of 386mph, they were introduced into service in 1948

I don't think ive answered your question, but Ive given you some information for thought just the same.

 

[wuzak]

The Mk I had a single stage Griffon and the Mk IV had a 2 stage Griffon.

No doubt the leading edge radiators reduced drag a little too.

 

[Zipper730]

Two variants of the Mk I Firefly were built; 429 "fighter" "Firefly F Mk I"s, built by Fairey and General A/C, and 376 "fighter/reconnaissance" Firefly "FR Mk I"s . . . The last 334 Mk Is built were upgraded with the 1,765 hp (1,316 kW) Griffon XII engine.

How did the Griffon XII compare in critical altitude to the initial Griffons?

. . . climb rate of 2,140 fpm (10.87 m/s) at 3,800 ft (1,158 m)

Slow climb-rate... I'm not sure if the P-47's better...

It has a published maximum speed of 367mp @14k, a range of 760 miles,

Wait, I thought the Griffon 70's had a twin-stage supercharger? You'd figure the critical altitude would be in the 20,000 foot range at least...

Im unsure why you would want the performance figures of the Mk IV, since it only had a limited production run

It had a redesigned radiator, a twin-stage supercharger, yet a reduced fuel load. I was curious how the more powerful engine compared with reduced fuel load.