Everything I've seen indicates a range of ~465 miles for the Defiant I with 103 gals of internal fuel however the Defiant II NF was modded in Aug 1941 to increase fuel capacity to 162 gals to increase patrol time as a NF.
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Let's be realistic; even a small increase in speed isn't going to make anything but a negligible difference to the Fulmar's combat capability (no one's doubting the kills made in it, but the Med was swarming with enemy aircraft). The Fulmar can be described as being the Boulton Paul Defiant of the FAA - without any derogatory connotations. Both were well designed and finely finished machines, which were easy to fly, but the concepts they were designed to were flawed in the face of modern combat scenarios. Another thing they both had in common was that there were very few of them in operation at any one time, facing overwhelmingly superior numbers of enemy aircraft. After a less than impressive innings as a day fighter (for which it was not designed - it was a bomber destroyer, not for fighter v fighter combat) The Defiant redeemed itself as a night fighter, but the fundamental problem with both types was that they were too slow, even after refitting with more powerful engines. This meant that both were always going to be replaced by better performing types. Both were also somewhat larger and heavier than their single-seat opposition.
Comparing the two, the Fulmar I was larger, heavier (9,800 lb loaded weight), had a shorter range (800 miles) and lower ceiling (26,000 ft) and was slower (280 mph, 1,200 ft/min rate of climb) than the Defiant I (8,240 lb AUW) (950 miles) (31,000 ft) (304 mph, 1,900 ft/min).
Fulmar figures from Fairey Aircraft since 1915; H.A.Taylor, Defiant figures from The Defiant File; Alec Brew.
I'll again call the Merlin 30 as 'Merlin 20 series with low supercharger gear only ', for the sake of comparison. The Hurricane IIC was making ~305 mph on low gear, ~325 on high gear, all at +9 psi boost. That's 7% increase in speed. 280 mph increased for 7% gives 300 mph, for the 'Fulmar III' (the hypothetical with Merlin 20 series).
For completeness, it was not an open sky encounter. It was an attack on a British convoy of five merchants, two carriers, two cruisers and nine destroyers (Operation Tiger). Due to bad wheater, that the British were taking advantage of, to avoid the chase of the Axis forces, the action of the Regia Aeronautica could begun only at 13:45, a time particularly unfavorable for torpedo bombers, who usually preferred to strike at dawn or dusk, to take advantage of the sun.
Italian records registered two (of six present) SM79 torpedo-bombers lost (Lt. Cappa and Cpt. Boetto), the first credited to the ships' defensive fire, and three Cr.42 for various reasons. In the action was shot down, by a Cr.42, the Fulmar of Lt. Rupert Tillard (Commander of the 808 squadron, fighter ace with 6.5 victories) and Lt. Mark Somerville, observer. Three other Fulmars were also damaged.
Don't know for the Germans, who attacked later, but I tend to believe that, even in this case, the fighters were responsible only for a part of the losses.
And should we average that with the speed increase of the Defiant when it got the Merlin XX?
The Defiant II managed 313mph at 16,500ft, a wopping 9 mph over the MK I with the Merlin III. The Defiant was a smaller airplane than the Fulmar.
First "Protoype" Fulmar (actually first production plane, there was no true prototype, initial "prove of concept" had been done with a modified P.4/34 bomber) managed 230mph with a Merlin III uprated to 1080hp. With a lot of work to clean up the engine installation and the fitting of the Merlin VIII engine they got the speed up to 255mph. Fitting the Merlin 30 got the speed up to about 270mph but the planes also had tropical equipment fitted and extra radio equipment. (antenna's may cause more loss of speed than the weight??).
A Fulmar's "Tare" weight was heavier than a loaded Defiant. You are going to need a LOT of power to get the Fulmar up to even the performance of a Defiant. And that gets you what in 1942/43??
And should we average that with the speed increase of the Defiant when it got the Merlin XX?
The Defiant II managed 313mph at 16,500ft, a wopping 9 mph over the MK I with the Merlin III. The Defiant was a smaller airplane than the Fulmar.
First "Protoype" Fulmar (actually first production plane, there was no true prototype, initial "prove of concept" had been done with a modified P.4/34 bomber) managed 230mph with a Merlin III uprated to 1080hp. With a lot of work to clean up the engine installation and the fitting of the Merlin VIII engine they got the speed up to 255mph. Fitting the Merlin 30 got the speed up to about 270mph but the planes also had tropical equipment fitted and extra radio equipment. (antenna's may cause more loss of speed than the weight??).
A Fulmar's "Tare" weight was heavier than a loaded Defiant. You are going to need a LOT of power to get the Fulmar up to even the performance of a Defiant. And that gets you what in 1942/43??
a range of ~465 miles for the Defiant I with 103 gals of internal fuel
The Defiant was also lugging around the turret, unlike the Fulmar.
It gets you somewhere in 1941, and certainly gets you more than with historical Fulmar.
But not of any significance to make any appreciable difference compared to the real thing. Still far too slow and in need of replacement. It would have been a waste of effort to build a 'Fulmar III'.
Yet the Defiant was still faster than the Fulmar.
But not of any significance to make any appreciable difference compared to the real thing.
Still far too slow and in need of replacement. It would have been a waste of effort to build a 'Fulmar III'.
Assuming that's done to a Fulmar II.A Merlin 45 with 16lb boost should bring the Fulmar well past the Martlet in performance.
The Spitfire V earned 25 mph over Spitfire II, Merlin 45 vs. Merlin XII as we know all too well.
The Defiant was also lugging around the turret, unlike the Fulmar.
As you can see, I'm advocating the 2-speed Merlin to be installed, so our Fulmar can actually fly at 15-20000 ft, hence taking advantage of thinner air there. The 270 mph speed mark was reached between 5-10 kft?
It gets you somewhere in 1941, and certainly gets you more than with historical Fulmar.
Who were they?It was a confusing action but Shores notes the loss of 4 SM-79s and two Cr-42s and identifies the flight crews.
The official 'Data Sheet' says:
permanent tanks (auxiliary tanks)
Fulmar I
Fuel Carried: 115 (215)
Fuel Allowance: 25 (25)
Range: 810 (1124)
Fulmar II
Fuel Carried: 115 (215)
Fuel Allowance: 25 (26)
Range: 795 (1070)
Defiant I
Fuel Carried: 162
Fuel Allowance: 20
Range: 950
Defiant II
Fuel Carried: 162
Fuel Allowance: 29
Range: 840
Who were they?
However, according to the report of "Royal Navy Aces of World War 2", it doesn't seems to me that the Fulmar had a so good day. Against a small group of low flying SM.79s burdened by torpedoes and escorted by Cr.42s (hardly the best escort you can encounter in mid 1941) they had two losses and a badly wounded TAG first to get their first strike.
Defiant with turret was only 15-25mph slower than a Hurricane with the same engine. Speed difference of the prototype Defiant without turret and versions with turret was under 10mph.
True on were the speed was reached but then most of the attacking aircraft against the fleet/convoys were NOT at 15,00-20,000ft. Granted you can dive but that is only going to work once per attack.
Merlin XX is (NOT) going to get you not much more than the Merlin 30 at low altitudes in 1941. When did the British allow the higher boost settings on the Merlin XX series engines?
The Italian engines had critical altitudes of between 3800-4200 meters for the most part. They were in no hurry to try to fight at 20,000ft.
The Merlin 30 was pretty much a Merlin XII with a cut down impeller ( 9.75in) and using the same supercharger gear as a Merlin III.
Tip speed was almost identical to the tip speed of a Merlin XX in low gear.
It did NOT have the improved Hooker designed supercharger inlet.
Fitting the Hooker designed inlet, some internal strengthening ( you can't just jack the boost on the early engines to what ever you want) and the engine was cleared for 18lbs boost as the Merlin 32 used in the Barracuda. 1640hp at 2000ft is as good as it is going to get for chasing torpedo bombers.
This is from the Historical Office of the Aeronautica Militare (in Italian, sorry).Shores gives the last names of the downed SM-79 pilots as Cappa, Marini, Boetto and Fonseca.
In any recip of the WW2 era, putting an extra crewman on a "fleet fighter" was a waste of time and manpower.