British escort fighter--what might it have been like?

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Actually, this is an entirely relevant point that I've been banging on about for a while now. How many B-17s or B-24s were available in 1941? In order to require long-range escort, you need long-range bombers. The best candidate in 1941 was probably the Wellington. Prior to early 1942, that was the type which had the longest legs and hence provides the mission profile that an escort fighter in the RAF would need to support.
 
... and which was clearly unviable;

to whit for a Wellington 1c: Maximum range, circa 2,500 miles (with what bombload?), service ceiling: a pathetic 18,000 ft (again, with what bombload?) and with a MAXIMUM speed of a mere 235mph - what's its operational cruise speed going to be!? It has a mere 8 0.303 guns spread between 2 turrets and two waist guns and no effective belly protection. The latter was bad enough at night, During the day, it would be a turkey shoot for any interceptor getting through the escort. (Early war encounters had long proven the vulnerability of all RAF medium/heavy bombers)

It has neither the ceiling or speed to provide any effective protection from flak or interception for daylight operation in contested airspace over land. Geodetic construction ain't the answer to being chewed to pieces,.

So our imaginary British long range escort is not going to have to be a superlative performer to offset this, but its also going to have to be available in huge numbers to offset that problem. Its also going to require genius tactics and fighter control to keep such disparately performing aircraft coordinated over enemy airspace. Oh, and success also probably needs to have as many sister squadrons of our wunder-escort operating in flak suppression role at low level.

Back to the real world of 40, 41 and 42 - although the Circus operations doomed so many young pilots to either an early grave or years of incarceration, they at least proved that, for all the flaws and compromises, the decision to switch to night operations for the bulk of Bomber Command was the best choice for the RAF, given its equipment at the time - or even with access to our best imaginings!
 
Mr Short was always too big for his boots.
 
To be somewhat fair Short's had both factories bombed which delay things in 1941 by a minimum of several squadrons, perhaps more.

But flying 5,000ft or more lower than the B-17s was not going to end well. The guns can shoot for longer period of time and the fuses are more accurate (errors are a function of the time set. Longer time means greater error). Flak kills a higher percentage of the bombers and escorts cannot help with that.
Using Wellingtons instead of 4 engine bombers means you have to use a larger number of bombers to get the same target effect. Now do more bombers dilute the enemy defenses or just give them more targets to shoot at?
 

According to the graphic "Radius of action of Allied aircraft from Malta in relation to Axis shipping routes, Summer and Autumn, 1941" appearing in the book History of the Second World War, Chapter 14, the Wellington I, with a bomb load of 4,500 lbs, had a radius of action of 480 miles. With the bomb load reduced to 1,000 lbs the radius of action increased to 900 miles.
 

Hawker Tornado, compared to the Defiant it had almost 3 ft more wingspan. about 33 sq ft more wing (13%) but the fuselage was about 2 1/2 ft shorter.
Accounts differ but it never hit 400mph and either had a Vulture II with 1710hp at 15,000ft when it hit 398mph or it had a Vulture V with ???? power.

Chances of a Defiant with 1190hp at 18,500ft hitting 360mph????

The Defiant was not a small airplane.

Maybe the guy standing to the turret was just made minimum height?
 
Funny how Portal's decision to not pursue a long-range escort fighter makes a lot more sense when you work out exactly what bombers it would be escorting. The Wellington and Stirling, operating at a maximum of 18,000 ft and 17,000ft weren't terribly survivable when going against defended targets. As others have observed, an escort fighter won't stop bombers being shot down by flak.

As has been pointed out before, even the USAAF didn't really get into long-range escort missions until well into 1943, when the P-38 and P-47 showed up in Europe in sufficient numbers. I can't help thinking people are collapsing the time horizon and assuming the superlative P-51 was available for much longer but it only truly showed up in 1944. The first long-range escort mission with P-51s appears to have been P-51Bs equipped with drop tanks in January 1944.

Even the much-vaunted Lancaster topped out at 21,400ft which still is nowhere close to the operating altitudes of B-17s or B-24s and is still right in the sweet spot for Flak 88s. Maybe...just maybe....the RAF leadership were smarter than some give them credit?
 
There was logic in Portal's decision but the high altitude recce/bomber risk over the UK prompted two designs to be made just in case. So Portal could have eschewed long range escorts but still asked for a design to be brought to prototype trials in case and when there was something to escort and daylight raids deemed desireable. Time enough for a Maxi/Super Whirlwind from Petter perhaps and ready for mid 1943 service in quantity.
 
Lets check the stats?

Defiant -
  • Length: 35 ft 4 in (10.77 m)
  • Wingspan: 39 ft 4 in (11.99 m)
  • Height: 11 ft 4 in (3.45 m)
  • Wing area: 250 sq ft (23 m2)
  • Empty weight: 6,078 lb (2,757 kg)
  • Gross weight: 8,318 lb (3,773 kg)
  • Max takeoff weight: 8,600 lb (3,901 kg)
  • Maximum speed: 304 mph (489 km/h, 264 kn) at 17,000 ft (5,200 m) with 1 × Rolls-Royce Merlin III liquid-cooled V12 engine, 1,030 hp (770 kW)

    Tornado
    • Length: 32 ft 10 in (10.01 m)
    • Wingspan: 41 ft 11 in (12.78 m)
    • Height: 14 ft 8 in (4.47 m)
    • Wing area: 283 sq ft (26.3 m2)
    • Empty weight: 8,377 lb (3,800 kg)
    • Gross weight: 9,520 lb (4,318 kg)
    • Max takeoff weight: 10,668 lb (4,839 kg)
    • Maximum speed: 398 mph (641 km/h, 346 kn) at 23,000 ft (7,000 m) (Vulture V)

      Hurricane
    • Crew: One
    • Length: 32 ft 3 in (9.83 m)
    • Wingspan: 40 ft 0 in (12.19 m)
    • Height: 13 ft 1.5 in (4.001 m)
    • Wing area: 257.5 sq ft (23.92 m2)
    • Airfoil: root: Clark YH (19%); tip: Clark YH (12.2%)[176]
    • Empty weight: 5,745 lb (2,606 kg)
    • Gross weight: 7,670 lb (3,479 kg)
    • Max takeoff weight: 8,710 lb (3,951 kg)
    • Powerplant: 1 × Rolls-Royce Merlin XX V-12 liquid-cooled piston engine, 1,185 hp (884 kW) at 21,000 ft (6,400 m)
    • Maximum speed: 340 mph (550 km/h, 300 kn) at 21,000 ft (6,400 m)

      And that is the Defiant WITH the drag and weight of the turret and an extra crewman, remember..... Given that it generally requires an exponential increase of horsepower for speed increase, the higher up the performance curve you go, I don't see why you'd think a speed of circa 360 with a cleaned up and and significantly lightened airframe with a more powerful 1,260 hp Merlin XX as per the Defiant ii (or better) is inherently unrealistic?


      Precisely because of the built in headwind and compromise of the turret, the Defiant designer did spend quite a lot of time trying to keep its performance high by paying attention to their aerodynamics.

      The Defiant certainly isn't a particularly large aircraft according to the above dimensions - the Hurricane has nigh-on the same wingspan and apparently sits higher on the ground too. Note it has marginally less wing area than the hurricane too. And that's also been backed by my personal experience - from my visits to Hendon, it didn't seem appreciably any larger than its contemporaries either.

      The enemy to the turreted Defiant it seems to me were (predictably) drag and weight, not engine power or size.
 
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Maximum internal fuel (if I have my math right) 262 gallons (forward fuselage 48 & 37 {lower/upper}, aft 48 & 33 {lower/upper}, 20 gal seat {from PR Spit; some said 29 in the linked thread, so anyone who can clear up the confusion, please do}, wing leading edges 18 &18 {port/starboard; based on PR Spit}, & 20 & 20 outboard {port/starboard; replacing gun bays}). Four 12.7mm Brownings in OTL gearwells. (No outboard guns. Six guns, as mooted off the top of my head, are not essential anyhow.) Wing modified with straight edge & outboard taper for simplicity, stressed to carry greater internal fuel & armament weight, plus two 75 gal teardrop (or "torpedo") wing drop tanks & one 120 gal teardrop (or "torpedo") belly tank. (Airframe generally stressed for higher weight than OTL 9500pd maximum.) Main gear struts stronger, possibly with additional fold to save space; main gearwheels somewhat smaller (& magnesium), to save weight & space; mounted to retract into OTL "twin" gun bays. Hollow-bladed prop (4 blades?).
 
SplitRz said:
The Defiant certainly isn't a particularly large aircraft according to the above dimensions - the Hurricane has nigh-on the same wingspan and apparently sits higher on the ground too.
Click to expand...
A key word is apparently. As in apparently who ever measured the height of the Defiant measured it with the prop at minimum height, one prop blade straight down instead of straight up. Look at the photo of the crew working on the Defiant and the two men standing on the step ladder. We have two possible explanations. Either the quoted measurement is wrong or the RAF was using the cast from the Wizard of Oz for ground crewmen.
SplitRz said:
The enemy to the turreted Defiant it seems to me were (predictably) drag and weight, not engine power or size.
Click to expand...
Weight gets a lot blame for poor speed. A Merlin Mustang lost about 3mph when they changed the weight by about 1000lbs.
Unfortunately for decades aviation writers have used "weight" for a shorthand for extra drag. "Plane X gained 454lbs and lost 18mph of speed". When really happened was plane X got different radio antennae's, more guns with ejection ports, (muzzles were usually taped over) changes to the radiator or changes to the wheel covers or other things that affect drag. Finding out all the changes and the change in speed for each one was often hard or the information simply was not available.

Speed is pretty much thrust (power) vs drag. At high speed the wing needs very little change in incidence to generate more lift.
Just look at the Spitfire, the weight of the BP glass, the rear view mirror, the IFF aerials, and the tail wheel (there is one for you, the non-retracting tail wheel weighs less) is pretty minor jet added together they were worth around 15mph in speed? (correction welcome)
On the other hand weight is very proportional to climb.
SplitRz said:
, I don't see why you'd think a speed of circa 360 with a cleaned up and and significantly lightened airframe with a more powerful 1,260 hp Merlin XX as per the Defiant ii (or better) is inherently unrealistic?
Click to expand...
3 things.
1, a cleaned up and significantly lightened Defiant is not a quick and easy fix. It is not a quick and easy fix on a lot planes. You have go through the whole airframe and decide what parts can be made smaller (thinner?) and lighter. And will the existing jigs and fixtures still work.
2. We know exactly what the speed difference is using the more powerful Merlin XX engine as it was used in all of the Defiant IIs.
We also know that somebody at B-P did a few of their sums wrong because the Defiant II did not quite get the speed gain they thought. But the drag did not stay constant. Bigger radiator/oil cooler, the radar aerials, the high drag, flat black paint. Pick one or more. The engine that gave the Hurricane around 20mph more speed was only worth 9 mph to the Defiant.
3. They had flown the prototype Defiant I without the turret and are supposed to have gotten 302mph out of it using a Merlin I engine. After some fiddling around like fitting the turret and changing the prop and getting it to production standard they managed to get the thing up to 304mph using the Merlin III engine. They should have known exactly what the turret was costing them. The 360mph speed was an estimate before they fitted the Merlin XX engine. First prototype with a Merlin XX engine flew July 20th 1940. How long it took to get good performance numbers I don't know.

Now using the cube law to estimate speed is very useful but it has a few problems, 1 is that it assumes no change in drag (like you don't need a larger radiator). 2. That your drag curves were correct to begin with. The British had a lot trouble with this one in the late 30s and 1940, how soon they got it straighten out I don't know but just about all of the airframe builders were told that thick wings would not cause a greater increase in drag going into the mid to upper 300mph area than a simialar increase in drag in the upper 200 mph speed area. The curve or coefficient was supposed to stay the same. It didn't.
I am not explaining this well. The Upshot was that pretty much aside from the Spitfire (Mosquito?) just about every British plane designed in the late 30s ran into a wall in the mid 300 speed area. The 4 engine bombers and all the the carrier bombers weren't flying fast enough for it to matter.
 

Data sheet for the Wellington Ia / Ic has:
4500 bombs - 1200 miles
2750 bombs - 1805 miles
1000 bombs - 2550 miles​

Above figures are at most economical speed (165 mph at 10000ft)
Max weak mix cruise is 195 mph

Max weight ceiling is 15,000 ft, 'mean' weight is 19,000 ft.

My guess is those Malta figures suffer from cruising at low altitude and having Vokes filters.
 
If we put a drop tank or three on a Spitfire for daylight escort over Germany, how does the Spitfire get home if the tanks must be dropped? Presumably in order to provide the necessary endurance the drop tanks are more than half the fuel load.
 
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Greyman said:
Data sheet for the Wellington Ia / Ic has:
4500 bombs - 1200 miles
2750 bombs - 1805 miles
1000 bombs - 2550 miles
Click to expand...
Well, take about 195 miles off the 1200 mile range for 1 hour of 'reserve' and you have 1005 miles, divide by 2 to get radius and and we get a 502.5 mile radius instead of Malta's 480 miles.
Maybe the plane at Malta needed a tune-up (new spark plugs and the air filter changed)
 
The reason for using the Spitfire is any new type means something else has to be cancelled to free resources. The ultimate is probably to turn up at the mid 1930's Spitfire design conferences and note when they decided to remove wing fuel tanks to allow heavier armament that one of two ideas will be correct. The self defending bomber works, in which case the Spitfire could be considered a waste, or the self defending bomber does not work, in which case the range of the day bomber is determined by the range of the day fighter, give the Spitfire I the VIII fuel tanks and point out the wing tanks can stay empty on intercept missions. A side line to this is self defending seems only to have applied to the heavy bombers with gun turrets, lighter bombers would still need escort, but they would be assumed shorter range missions and without radar would be much harder to intercept.

Try and run a bombing campaign against Germany from Britain with Holland and Belgium neutral. The Spitfire I had a range with combat allowance range of 395 miles at economic cruise, say 300 miles fast cruise/150 mile radius, add a 30 to 50 gallon drop tank and base the fighters in France, lots of Germany in range, especially the Ruhr. As a more "realistic" pre WWII thought, assume WWI results, Belgium is invaded but not Holland and the front line becomes fixed around the WWI lines. Better direct routes from Britain to Germany, bases in France for fighters.

London Hamburg is about 450 miles, London Cologne is around 310 miles, Paris Cologne about 250 miles, Metz Cologne 130 miles. In July 1940 the RAF requirement for an escort goes from standard Spitfire I with drop tank to something with a 400 mile radius

Fixed+Removable weights in pounds, Lancaster turrets, 261+179=440, Front turret (FN.5A) Guns and ammunition (2,000 rounds), 320+179=499 Mid Upper turret (FN.7) Guns and ammunition (2,000 rounds), 370+490=860 Rear turret (FN.20) Guns and ammunition (6,000 rounds). I am sure someone has the Boulton-Paul turret and armament weight for the Defiant.

Hurricane armament weights, pounds
212 8x0.303 inch
9 case and link chutes
202 2,660 rounds ammunition and boxes
423 Total

425 4x20mm
327 364 rounds ammunition and boxes
752 Total

The Defiant I is reported to have about the same range as the Spitfire I as does the Whirlwind. The following ranges make no allowance for formation flying, combat etc.

Wellington Ia,Ic
Overload Weight (pounds) (Max bombs (or Fuel if same))
30,000​
Take Off (Over 50 ft) (Yards)1,250-1,350
Climb to Height (feet)
10,000​
Climb to Height Time (mins)
25​
Service Ceiling
16,000​
Maximum Bombs (Cruise)
Speed (m.p.h)
195​
Height (feet)
10,000​
Bomb Load (pounds)
4,500​
Range (50 mins allow.) (miles)
1,055​
Endurance (50 mins allow.) Hrs
5.4​
Fuel (for range, pounds)
3,370​
Fuel (for allowance, pounds)
518​
Fuel (Total, pounds)
3,888​
Fuel (Total, Gallons)
518​
Miles per 100 pounds of fuel
31.3​
Maximum Fuel (Cruise)
Speed (m.p.h)
195​
195​
Height (feet)
10,000​
10,000​
Bomb Load (pounds)
2,800​
500​
Range (50 mins allow.) (miles)
1,600​
2,255​
Endurance (50 mins allow.) Hrs
8.2​
11.55​
Fuel (for range, pounds)
5,102​
7,202​
Fuel (for allowance, pounds)
518​
518​
Fuel (Total, pounds)
5,620​
7,720​
Fuel (Total, Gallons)
750​
1,030​
Miles per 100 pounds of fuel
31.3​
31.3​
Capacity (Gallons)
750​
1,030​
Maximum Fuel (Economical)
Speed (m.p.h)
165​
165​
Height (feet)
10,000​
10,000​
Bomb Load (pounds)
2,800​
500​
Range (50 mins allow.) (miles)
1,805​
2,550​
Endurance (50 mins allow.) Hrs
10.95​
15.5​
Fuel (for range, pounds)
5,102​
7,202​
Fuel (for allowance, pounds)
518​
518​
Fuel (Total, pounds)
5,620​
7,720​
Fuel (Total, Gallons)
750​
1,030​
Miles per 100 pounds of fuel
35.4​
35.4​
xxx
CharacteristicDefiant IWhirlwind I
Weight (pounds)
7710​
9,980​
Take Off (Over 50 ft) (Yards)
500​
630​
Landing (Over 50 ft) (Yards)
770​
750​
Climb to Height (feet)
15,000​
15,000​
Climb to Height Time (Mins)
8.5​
5.6​
Service Ceiling (Feet)
30,000​
30,500​
Maximum Speed (m.p.h)
304​
356​
Max Speed Height (Feet)
17,000​
15,000​
Endurance (Max Power, hrs)
0.95​
0.59​
Cruising Speed (m.p.h)
260​
306​
Cruise Speed Height
15,000​
15,000​
15 Minutes allowance Range (miles)
465​
340​
15 Minutes allowance Endurance Hours
1.78​
1.11​
Fuel (for range, pounds)
635​
645​
Fuel (for allowance, pounds)
145​
240​
Fuel (Total, pounds)
780​
885​
Fuel (Total, Gallons)
104​
118​
Miles per 100 pounds fuel
73.2​
52.7​
Maximum Fuel Capacity (Gallons)
104​
136​
Maximum Fuel (Economical)
Speed (m.p.h)175 - 180
190​
Height (feet)
15,000​
15,000​
Range (15 mins allow.) (miles)
580​
590​
Endurance (15 mins allow.) Hrs
3.25​
3.1​
Fuel (for range, pounds)
635​
780​
Fuel (for allowance, pounds)
145​
240​
Fuel (Total, pounds)
780​
1,020​
Fuel (Total, Gallons)
104​
136​
Miles per 100 pounds of fuel
91.3​
75.7​

There were 3 Short Stirling production lines, 2 were bombed with six Stirlings at Shorts and five at Short and Harland destroyed on the production line and claims it set back production at Shorts by a year. First 12 months of production, Shorts (May 40 to Apr 41) 15 aircraft, Harland (Nov 40 to Oct 41) 63 aircraft, Austin (Mar 41 to Feb 42) 57 aircraft, Handley Page Halifax (Oct 40 to Sep 41) 96 aircraft, Avro Manchester (Sep 40 to Aug 41) 133 aircraft, the Manchester factory was also bombed losing 1 aircraft. The bombing of the Harland factory was in August 1940, before production began and destroyed the 26th to 29th and 32nd production airframes, the ones lost at Shorts also in August 1940 were the 11th and 13th to 17th.

By end 1941 you could choose between the Wellington Ic (Pegasus), II (Merlin), III (Hercules) and IV (Twin Wasp)

Germany had fewer flak guns in 1941/42 than 43/44 and far fewer radar equipped fire controls.

The RAF did not lose many bombers on escorted day bomb raids to France in 1941/42, it did lose many on unescorted raids and the low level channel stop operations against shipping. 1941 Blenheim day bomb raids to France, 72 attacking sorties, 3 missing, day anti shipping raids, 100 attacking sorties 13 missing. The Stirling sorties in July 1941 had 52 attacking sorties, 3 missing. The 24 July 1941 raids on Brest and La Pallice only provided escorts for the 18 Hampdens and lost 17 out of 115 bombers sent (no Stirlings on this raid)
 
Hi
Just to compare size of Hurricane with the Defiant in similar pose:

Mike
 
ww2restorer said:
The British did have a superior escort fighter, it is called the P51. It was conceived from a British specification or order.
Click to expand...
Specifications 1592 dated 3-11-40 and 1620 for XP-51 dated 4-20-40 were written by NAA. Both RAE and RAF were consultative to NAA wth respect to cockpit layout, increase to fuel from 156 to 170gal, exhaust stack and final decision on armament.
 
The best approach given a high enough priority would have been for the Air Ministry to ask Supermarine and Hawker to propose and build a fighter circa 1939. stating single engine, performance equal or greater than current fighters, with a range of 1500 miles.

The AAC actually set this priority as #1 but Materiel Division in its infinite wisdom assumed that only T/E design like P-38 could meet the requirements - which drove the P-61 development. MD remained short sighted until the XP-75 disaster in early 1942.

From my perspective, the first approach would have been wing re-design (internally) to see if 50+ gal in each wing could be accomodated but still retain 4x20mm or even 4x50 cal with same airfoil section. However, going to a NACA 23015/16 would only have adversely affected critical Mach but probably offset with higher CL at low speed. The drag of the wing would be slightly higher affecting range in cruise envelope.

The spars/skin variations would solve for AoA loads due to extra 600 pounds, but longerons and load paths from empennage would have to be lookd at.

Supermarine/Hawker didn't do it because they weren't asked to do so - but they had the talent.

Corporate inertia was a factor in US. IMO Kartaveli's penchant for not adding drag or messing with aft CG, retarded the P-47 from being effective LR fighter until they were replaced by the Mustang or P-38.

The AAF (Arnold) issued Pursuit Range extension at Fighter Conference Feb 1942.

Lockheed already had wing pylon/fuel feed nailed with modified P-38E thanks to back door collaboration between Ben Kelsey and Kelly Johnsom contra AAF policy then in effect for external fuel tanks.
NAA had already incorporated same with A-36 Preliminary design.
Crickets from Republic.

Between the Fighter Conference 2-42 and 7-43
Lockheed
Installed wing pylon and fuel feed on every model after P-38E
Installed 2x55gal LE tanks in prototype P-38J and every model afterwards.
Designed and built 165 and 330 gal Ferry Tanks

NAA
Installed wing pylon and fuel feed on A-36 and every P-51 model aftewards
Installed prototype 90 gal fuselage tank, designed 85 gal self sealing fuse tank
Designed and built 60gal and 150gal external ferry tanks
Designed pressure pump for external tanks, but only inserted in November.
85 gal kits produced for 1200 conversions in September, delivered to ETO Depots in November.

Republic
Designed keel with B-7 racks in December 1942
Designed and built unpressurized 205 gal Ferry Tank
Production Pylon w/fuel feed? Crickets.
Increase to internal fuel tankage? Crickets.

The D-5 (six articles) was modified to carry 165gal Lockheed Ferry tank - July 1943
The D-15 production wing with Pylons was in preliminary design in September.
The D-25 production auxillary 65 gal tank was in preliminary design in September and D-25 drawings released in mid-December 1943.

Status December 1943
P-38J LE kits being installed, already arrying 75 ga combat tanks and 165gal Ferry tanks.
P-51B 85gal kits being installed, already carrying 75gal combat tanks.
P-47C/D carrying one C/L 5, 110 or flat 150 gal flat tank

Through May 1944
Only P-51B/P-38J capable of target escort to Berlin, Poland or Ploesti
Through lack of commitment (IMO) to dirty up his airplane, Kartaveli's fine design was relegated to intermediate range escort and rapidly being converted to P-51B

I believe Supermarine and Hawker could have responded to a request to deliver a 1500mi escort fighter had they been asked - with the opening caveats in mind.
 
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