WesWorld

USAAF Mission to Britain September 1942

Personal Notes of Henry L. Stimson, Secretary of War

September 8
We arrived in Britain today for our mission to Britain. We have been invited to visit and see for ourselves several items of interest and to observe an RAF excercise. Later this year a reciprocal visit will be made to the States. Yesterday we stopped over at Foynes in Ireland aboard the PanAm Clipper after our non-stop transatlantic flight. After breakfast this morning we took off from the Lough and flew direct to Southampton where we taxied into the BOAC terminal at 108 Berth. After being ferried ashore we were met by the British reception committee, led by the Secretary for Air, John Moore-Brabazon (also known as the 1st Baron Brabazon of Tara). After a quick introduction on both sides of who was who we set off for the hotel to unpack and rest for the evening. We had the whole top floor to ourselves and we mixed with some of the locals in the bar that night. A few of our British hosts are also at the hotel and I had an opportunity to talk with John Brabazon with General ‘Hap’ Arnold and some of the other officals in the Mission on general aviation topics. Among other items we discussed airports and the new works at on the outskirts of London to build a new modern airport.

September 9
Visit to Farnborough
We left the hotel and were transported in convoy to RAE Farnborough. Today we were to be admitted to the SBAC Show which was showcasing the latest developments in British aviation. Today was a closed day for “tradesmen” only, in particular foreign military officials.

The Hawker Siddeley area was very large and filled with every type of aircraft and engine you could imagine. We met Sir Tom Sopwith, the Chairman of Hawker-Siddeley who was our guide around his combine’s products. Tom is one of the founders of British aviation and was very knowledgeable about the latest technologies. Also on hand were Roy Dobson, general manager of Avro and two designers, Sidney Camm and Roy Chadwick who have great standing among designers.
There were three fighters on show, the prototype Hawker P.1022 Sea Fury and the P.1017 Tempest series. It is fair to say both the P.1017 and P.1022 are related and both are descended from the Hawker Tornado and Typhoon now in service with the RAF. The Sea Fury was of great interest, it is roughly the size of the F4F Wildcat yet its top speed of 460mph at 18,000ft is far faster than anything even in the pipeline in the States. It’s 2,470hp Bristol Centaurus VIII radial is more powerful than the Pratt & Whitney R-2800 radial in the F4U and F6F. The Sea Fury is a sleek lightweight fighter, an exact opposite from the F6F, to see it thrown about the air during a display was an amazing experience. Sidney Camm is noted in Britain as among the supreme of fighter designers and his Tempest series leaves nothing to be desired either. Some of our technical boys were convinced that the Brits had made a mistake in ordering a fighter with three different types of engine; it implied a weak engine supply chain or indecision at the top. The Tempest I is powered by the massive 2,340hp Napier Sabre V H-24 engine, the Tempest II has a 2,420hp Rolls-Royce Griffon III V-12 and buried wing radiators, the III is fitted with the 2,500hp Rolls-Royce Vulture IV H-24 engine. Speeds of almost 470mph have been recorded in testing so far. Such speeds seemed almost unthinkable, these sleek machines obviously had massive engines but it sounded like propaganda. One of our test pilots later in the day flew the Tempest II for himself, he got 450mph out of it easily enough and the fighter proved agile enough to match the latest types. He compared it very favourably to the new P-51 despite lacking laminar-flow wings. It seems that the three Tempests are destined to serve in select operational environments and in certain roles.
We had a couple of engineers from the civil side who were interested to see Avro’s much talked about new airliners. Britain has lacked large airliners for several years with cutting-edge performance. Chadwick showed us around the York and Tudor. The York is a basic tailwheel aircraft more suited to cargo than passengers. It cabin seemed dour and certainly not suited to first-class travel. ‘Hap’ pointed out the use of the Lancaster bomber wing, Chadwick said it made economic sense to keep the parts down and tooling costs and that the wing was ideal of lifting heavy loads over long distances. ‘Hap’ wasn’t convinced but Chadwick pointed out Boeing had done the same on the Stratoliner. The Tudor takes the York wing and further refines it and has a sleek airliner pressurised fuselage with tricycle undercarriage. The cabin is much improved and it offers a fairly good standard of accommodation. The use of diesel engines is still fairly novel on airliners and it’s still open to question if their use will catch on. The Tudor matches the new Consolidated Model 39 airliner in performance but is a slightly larger in size and capacity. Boeing has bigger designs on the drawing board and Douglas will soon surpass the capacity, even if not the range with its forthcoming designs based on the DC-4. Still Avro has another two Tudor variants in development with a full range of other engine options so competition will be tough.
‘Hap’ Arnold was keen to see the Lancaster B.Mk.I and it was out first glimpse up close of this new bomber. With its black night bomber paint it looked menacing on the ground. The defensive armament in powered turrets is superior to our defences on the B-17 and B-24 but is behind the remote-controlled systems now being readied for the B-29. The bomb load is also superior to our older bombers but the B-29 will surpass the 14,000lb load. Overall its comparable to the B-24 in performance with a slight range advantage, and RAF official with us said the Lancaster could take a bomb load to Berlin. With these bombers now entering service across the British Empire many areas of the world will fall beneath their wing shadows.
Gloster in British terms is a small company, in American terms we’d probably see them as a minor player. However they have the one aircraft in the world that will steal the entire show and one we have waited a long time to see. The prototype Gloster G.40 Pioneer W4041 was present. We didn’t see it fly today but we were promised a full private showing tomorrow. The small aircraft looks fighter-like, it has a nose-intake and a tail jet-pipe. It is fitted with an 1,160lb W.1A thrust Power Jets W.1 centrifugal turbojet. With this engine it can reach over 390mph easily, faster than our new Bell P-63 Kingcobra fighter. As a testbed it looks fairly basic but then the radical engineering is all in the engine bay. The whole team was excited to see this creation fly, it all well and good to see the German engines but this is something much more lively.

We made our way to the AIRCO stands. AIRCO is a recent merger of the famous manufacturers of de Havilland, Handley Page and Fairey. Geoffrey de Havilland and Sir Handley Page are two other famous pioneers and they showed us round their products.
De Havilland’s military aircraft were on show, a production D.H.103 Hornet FB.Mk.I, the DH.98 Mosquito B.Mk.III fast day-bomber with added underwing racks and the brand-new prototype D.H.103 Sea Hornet which only flew for the first time a few days ago. We had heard much about the Mosquito from attaché reports and the actions in Afghanistan in the hands of Irish pilots. The Mosquito Mk.I can reach 386mph we were told the revised Mk. III can make 415mph making it very hard for any fighter to catch at altitude in a pursuit. At low-level it can attain over 300mph and again fighters and defending AA batteries have a hard time to defend against them. It is roughly comparable to our new B-26 in terms of speed and bomb load but the “Mossie” is built of wood and has no defensive armament at all. Geoffrey confirmed that a fighter-bomber variant with eight nose guns would enter production next year. The fighter-bomber Mosquito will probably step on the toes of its little sister, the Hornet. Designed as a long-range escort fighter and fighter-bomber it is powered by two 2,375hp Rolls-Royce Griffon II V-12 engines, top seed 472mph at 22,000ft and range is 1,500 miles. Four 20mm cannon are carried in the nose. One of our test pilot team had a good look inside the cockpit but wasn’t allowed to fly it, but Geoffrey de Havilland Jnr. gave a display for us. He is a fine pilot and he pulled some good aerobatics in it. It even full well with one propeller feathered. It surpasses the Lockheed P-38 and P-49 but the Hornet lacks a pressure cabin. The Hornet is also wooden in construction and was designed specifically for the Far East. It’s hard to see any real competitor in that region to beat it. Brazil is also a satisfied customer and as yet we have nothing with which to match it. The Sea Hornet is the same aircraft but with folding wings and naval equipment. It is designed to operate off the new Audacious class carriers now building and gives an indication of their flightdeck size and capacity. The USN has nothing in its class even in development. Whether such an aircraft can replace the scout bomber is open to question but it offers superior performance and a long-range punch against enemy forces. The prototype Balmoral B.Mk.II day bomber powered by a 2,420hp RR Griffon III V-12 engine was also on show as was the Barracuda AS.Mk.III in mock-up form only. It wasn’t overly impressive but seemed serviceable enough. The key feature of the Barracuda AS.III is the ASV Mk III centimetre-wave radio-location gear for attacking surfaced submarines and small vessels. The precise specification of the RDF set wasn’t given to us but certainly we got a better insight than some other nations present as they showed us some test materials and its performance looks equal to anything Germany has achieved and certainly our engineers should easily be able to match its performance.
Sir Handley Page showed us around his firm’s four-engined H.P.57 Halifax aerial tanker for the RAF. It is the first purpose-built aerial refuelling tanker in the world, with equipment developed and tested by Flight Refuelling Limited since the early 1930s. We had numerous experiments with aerial refuelling in the 1920s but haven’t taken it further. Both firms have hopes of commercial use with BOAC soon for flying boats and then for airliners. How the public will react is open to question but the ability to launch bombers with heavy bomb loads and small fuel loads and then refuel them in the air en-route to the target offers a huge increase in payload and range efficiency. Visions of patrolling fighters kept aloft for long hours is also a possibility. Britain certainly has a world-leading edge in this technology. Footage of trials seemed impressive and the lack of any accidents was also commendable. We were promised to see more of this equipment tomorrow.

The British Fleet Air Arm is one lucky branch! Not only do they have the Sea Fury and Hornet but also another third fighter. The Supermarine-Vickers Seafang. This sleek fighter is based on the basic layout of the Spitfire but with a new inward retracting undercarriage, 2,035hp Rolls-Royce Griffon VI V-12 engine, folding wings, arrestor hook and bubble canopy. Quoted max speed is 452mph at 20,500ft with a range of 940 miles with external fuel and a service ceiling of 43,100ft. It’s a performance superior to even most of our USAAF fighters, and the armament of four 20mm cannon is hard hitting. The Spitfire has some reputation out here and this fighter has all the best attributes of that machine and something extra. Supermarine’s noted test pilot Geoffrey Quill took her up in the afternoon and the Sea Fang and Sea Fury made a heady match in the sky. It’s a sure sign that the Brits intend to be superior at sea in all aspects, they don’t intend to be defenceless from enemy strike formations. The new laminar-flow wing Vickers-Supermarine Spiteful fighter for the RAF won’t be ready until next year but its designer George Smith gave us some useful insights and our engineering team compared it to the P-51 but the Griffon engine promises much more horsepower and 475mph seems a reasonable figure if the laminar-flow wings can be made to work well. Britain still lags behind in this regard. Westland had their Welkin high-altitude fighter on static display. For some time we had wanted to get an assessment of this type, it had been developed under tight security and then had been publically revealed only to slip back under the veil with rumours of permanent grounding. We have had some troubles with our P-49s but it seems the Westland engineers are slowly fixing the problems with the pressure cabin. Also they have found serious problems at speeds near compressibility in dives. I knew a little about this but ‘Hap’ and his boys seemed genuinely interested in the phenomena. As the airflow nears the speed of sound, a host of new aerodynamic effects become important in the design of aircraft. These effects are largely uncharted and many feel they will prevent any propeller-driven aircraft to reach speeds much beyond 500 mph. As many of the new British fighters are nearing this limit, their diving speeds will press right into this unknown area. The new turbojets will probably enable us to go further but first we need to define new aerodynamics for the airframes. As so often in the past the engine technology outstrips that of the airframes. Also noted was the Martin-Baker M.B.5 fighter, another Griffon-powered fighter than seems to have designed by a tiny firm but so good that the Air Ministry has ordered the type. Its construction is very simple and easy to maintain and repair and its controls are judged to be perfect. 460mph is claimed and the M.B.5 was ably flown by Captain Baker, a founding partner of the firm, and his display with a ten-foot high pass finished with a barrel roll was very impressive. Boulton Paul had on show a full-scale mock-up a proposed carrier-based version they are currently working on. This small firm has a good product but we sensed that the British would do better to stick to known firms and mass produce the right goods. We had seen so many programmes, they all might be successful but its wasteful. We felt the industry had a long way to go towards consolidation.

We had some opportunity to see some other RAF bombers. The brand-new prototype Type 447 Windsor heavy-bomber was absent but the Vickers team gave us a rundown on the type and it seems to be intended for the B-29 class in capability but its geodetic construction isn’t as advanced as it once was and overall it didn’t make much of an impression on us. Also on show was a Bristol Beaufort GR.Mk.III, equipped with ASV Mk.III RDF and the same firm’s Buckingham B.Mk.I bomber which was also flown. This is a cross-between the B-25 and B-26 but with superior range, it is powered by two 2,520hp Bristol Centaurus II radials and has a powerful defensive armament and can carry 4,000lbs of bombs.

Hi!

Will the Welkin and the Seafang be the same failures they were OTL?

Thanks,
HoOmAn

The WW Seafang is the OTL Seafire to rough specs of the Seafire 47. It is not the same as the OTL Seafang.


Dimensions; 36.11/ 34.4/ 12.9/ 243.6 sq ft; 1x 2,035hp RR Griffon VI; max speed 452mph at 20,500ft; range 940 miles with external fuel and service ceiling 43,100ft.

September 10
Visit to RAE Farnborough

After a comfortable stay in a local county house rented by the Air Ministry for our use overnight we returned to RAE Farnborough, this time to visit the working side of the airfield. Farnborough is one of the birthplaces of British aviation and today the Royal Aircraft Establishment has here a full range of wind tunnels, laboratories and hangars testing every new development and aircraft in Britain. During our visit there were a wide variety of aircraft on the apron or in the hangars away from prying eyes over at the air show press day. We noticed at least two Supermarine Spitfires, four Hawker Tornados and Hawker Typhoons, two Hawker Tempests, two Westland Welkins, a Boulton Paul Nighthawk, a Vickers Wellington, two Mosquitos, a Bristol Buckingham, the only massive Bristol Type 159, the Supermarine Type 323 and Handley Page HP.75. Also present on site is the Refuelling Trials Flight with a small fleet of old bombers, the High-Speed Flight with special marked and souped-up Spitfires and Hawker Tornados and the Rotary Wing Flight with Flettner Fl-282s and ShinRa Aviation Liasopods.

We headed over the to the small hangar allotted to the Refuelling Trials Flight. One of the Flight Refuelling engineers gave us a tour of the inside of the converted Whitley tanker. At the forward end of the bomb bay, attached to the roof, was the hose drum, hose guide roller and the hose drum winch. Towards the rear was a fuel tank. As we entered the rear fuselage the engineer pointed out the ejector gun, and contact winch on the port side. Over the bomb bay was another fuel tank. The Whitey was fuelled and took off, we assembled and took off in a de Havilland Hertfordshire transport to witness an in-flight refuelling. A Boulton Paul Birmingham four-engined heavy bomber, equal to our B-17, flew roughly parallel to us but lower, it was trailing a hauling line with a sinker weight and pawl grapnel on the end. The Whitey formatted to its starboard side and slightly behind and fired its contact line across the hauling line. A projectile on the end of the contact wire caught the grapnel on the end of the hauling line and the Whitley began winching the hauling line in. Once inside the Whitley it was attached to the hose and the Whitey climbed above the Birmingham, but remained astern. The Birmingham then winched the hauling line back with the hose line attached to the pawl grapnel. It connected into a reception coupling below the rear turret. Gravity fed the fuel through and at the end of the procedure the Birmingham trailed some of the hose and line back out and then the Whitley began climbing, a pre-built weak-link in the hauling line snapped and the line was separated and the each aircraft reeled in its line. The whole process seemed simple and hazard free as long as the tanker and receiver maintained correct formation. We were told 100 gallons had been transferred and the whole operation took about eight minutes.

On landing we had some lunch in the officer’s mess hosted by RAE Commandant Group Captain Allen Wheeler before heading to the secret compound. This area is on the opposite side of the airfield and is cordoned off with corrugated iron fencing and policed by armed RAF Police. It is a collection of sheds and hangars and at first impression seems rather ramshackle After the necessary security checks were made we were ushered into one of the hangars. Inside was filled with tools and in the middle with of this activity was the one aircraft we had travelled to see, the Gloster G.40 Pioneer. The first practical jet-propelled aircraft in the world. An RAF pilot, Wing Commander Wilson, was there as were some RAF fitters, a couple of Power Jets engineers. Then Gloster’s Chief Test pilot Gerry Sayer and the genius Wing Commander Frank Whittle walked into the hangar after they had briefed our pilot. I and General Arnold had a long talk about the theory of the jet engine and the engine itself. It genius is the simplicity of its design and the self-sustaining nature of the jet engine as the turbine drives the compressor that keeps the turbine fed with air to be burnt with fuel. We learnt that compared to piston engines that the jet required less between flight maintenance and the catalogue of problems was quite short.

The G.40 was pushed outside and soon hooked up to a starter. The engine spun up rapidly with a sharp whine and the RAF mechanic jumped out of the cockpit and Maj. Masterman was strapped in, Sayer was on the steps giving some last minute advice and then after he waved the chocks away began to taxi out. Here is an extract of Maj. Masterman’s report.
“I advanced the throttle to around 15,000rpm and some slight movement began, Sayer had advised to watch for brake over-heating as the idle thrust could be quite high. As I went over 16,000rpm the taxi-run picked up pace. I braked gradually, reducing power and waited at the threshold before gaining take-off clearance. The tower was quick to give the all-clear and I increased power steadily. I had been warned about abrupt throttle changes. As speed increased the tricycle undercarriage kept the aircraft straight, there is no torque-swing as associated with propeller-driven aircraft. It was quite evident in the cockpit from rotation that the cabin is much quieter and there is an absence of vibration. I was warned about the sensitivity of the elevators and eased the aircraft up; it needed a little assistance to get airborne due to the lack of propeller slipstream over the elevators. I rapidly climbed to 25,000 feet and began a high-speed run; I measured 380mph but was advised against pushing the engine too hard as this was the only aircraft of its kind flying so far. I felt there was some power left to exploit. This speed was equal to the maximum of the Bell P-39 Airacobra which I have extensively flown. At higher altitudes the performance is far better than any comparable propeller-driven aircraft. I then carried out manoeuvrability tests, again the British were anxious I shouldn’t risk the aircraft but Sayer’s advice had hinted at what could be achieved. It was not quite up to fighter standards, the elevator is still sensitive and full aileron did induce yaw at high speeds but at slower speeds the G.40 is quite agile, it is a small aircraft and the engine provides more than enough power for combat manoeuvres to be flown. The rate-of-climb was high; it could easily outpace a piston-powered fighter. Overall the aircraft gave good confidence while being smooth throughout and surprisingly quiet in the cabin. I then noticed that fuel was rapidly being consumed so began a let-down for landing. I quickly received clearance to land and was told to circuit the airfield. I had been warned that the jet is slow to spool up should an overshoot be necessary so I left the throttle open more to allow me some speed. The aircraft was smooth and despite the elevators landed well. The main wheels touched down with a slight bounce and then as the airspeed fell the nose wheel touched down. I applied brakes and chopped the remaining power. By the time I had taxied back to apron I was noticing brake-fade. I switched off and the jet wound down, I opened the cockpit and the ground crew disconnected me from the seat and they pushed the aircraft back into the hangar.”

After this short display we went over the airframe and Whittle pointed out the salient features of his engine and then we retired to the mess for supper before heading back to the hotel. It was our opinion that a fighter aircraft is ideal for this powerplant, it offers superior performance, especially at high-altitude. That the G.40 could be developed into a fighter this early into its development shows its potential, and that of the jet-engine. This type of engine could solve our future high-altitude defence problems.

September 11
We rose early and took the train to Rolls-Royce’s Barnoldswick factory. Frank Whittle had created Power Jets Limited as a private-public company owned partly by the Air Ministry to develop his engine. Since then an agreement was signed with Rolls-Royce that they would produce all of Whittle’s designs, and their own, leaving Power Jets as a design authority. Power Jets has now been subsumed into the RAE’s own programme into the new National Gas Turbine Establishment based at Pyestock. Rolls-Royce, with Air Ministry funding has built the Barndoldswick factory as its prime jet production line.

It would be fair to say that this factory is not quite like the mass production line methods we employ in the States. It is equipped with the latest in machine tools and lathes and lacks little for equipment but it is nevertheless not built to standard of American factories. We were met by a delegation of Rolls-Royce and Air Ministry officials and were given a tour of the factory floor. There were about thirty engines in various stages of assembly. In development at the moment are Whittle’s own designs and Rolls-Royce’s own projects. The 1,200lb thrust W.2 engine is now almost ready to begin flight trials. Speaking to Whittle yesterday he felt that the centrifugal compressor offers superior resistance to surging and less technical risk than axial-compressor designs now under way in Germany. While the centrifugal engines are wider, by using Whittle's reverse flow design, in which the combustion chambers are placed around the turbine produces a shorter engine. The airflow is more stable and although an axial-jet will probably become superior in the long-term, it is felt that with today’s technology that the Whittle design offers less risk and a workable engine available now, rather than five years’ time. Also pointed out was the higher time between overhauls of the British engines and their superior performance. The 1,200lb W.2 is a development of the W.1 series, and this engine will power the second Gloster G.40 research aircraft pushing the speed envelope into the 400 mph region.
We saw the first batch of Rolls-Royce’s RB.23 test engines under construction. This will be rated at 1,700lbs thrust. It was designed by Frank Whittle's team at Power Jets Limited but Rolls-Royce’s Stanley Hooker joined the team and added his experience in turbocompressor design. The RB.23 is a larger version of the Type W.1. The engine uses a single double-sided centrifugal compressor with the compressed air being taken off at several ports around the extreme outer edge of the compressor disk. It uses Whittle's reverse flow design. This requires the heated air to flow forward before reversing its direction to pass through the single-stage axial-flow turbine. The impeller is 19 inches in diameter and there are ten flame cans. The entire engine weighs about 850 lb. Bench testing has now begun to validate the design and one recently flew in a piston-engined testbed. It is hoped a flight-ready RB.23 will fly in the third Gloster G.40 in early 1943.
Rolls-Royce are working on a further development that dispenses with Whittle's reverse flow design, and instead has an axial-flow design, this might attain over 2,000lbs thrust and should fly during 1943. Engines of up to 5,000lb thrust seem possible within a few years. The RB.23 is rumoured to be for the new Gloster G.41 twin-engined design which has been described to us as “a fighter” but no details were forthcoming. If this is so General Arnold conjectures a first flight late next year with possible entry into service in late 1944 or early 1945. Perhaps a year or so ahead of any other nation and with engines that are technically among the best anywhere being developed and obviously of high quality and technical maturity as we have seen. We saw a W.2 being bench run and the full 1,700lbs thrust was attained while we were present.
After an interesting visit to the factory we toured the design shop after lunch and then caught the sleeper train to London.

September 12
The entire day was spent in talks with the Air Ministry on several matters, information exchange and planning for the forthcoming RAF exercises. I had a meeting with the Foreign Secretary Anthony Eden in the afternoon with my British counterpart, Secretary for War Oliver Stanley.

September 13
RAF Exercises

We arrived at the Headquarters of No 12 Group, Fighter Command at RAF Watnall. We were official observers of Exercise Emperor V, the RAF’s annual full-scale aerial defence exercise.
No 12 Group is providing the fighter element for Blue Forces;
Duxford Sector
19 Sqn, Supermarine Spitfire F.Mk.III
56 Sqn, Hawker Typhoon F.Mk.I
266 Sqn, Supermarine Spitfire F.Mk.III
609 Sqn (West Riding), Hawker Typhoon F.Mk.I
Coltishall Sector
25 Sqn, Supermarine Spitfire F.Mk.IV
74 Sqn, Supermarine Spitfire II & F.Mk.III
Wittering Sector
32 Sqn, Supermarine Spitfire II
43 Sqn, Supermarine Spitfire II

No 11 Group is providing the fighter element for Red Forces
Hornchurch Sector
81 Sqn, Hornchurch, Hawker Tornado F.Mk.I
1F Sqn, Hornchurch, Hawker Tornado F.Mk.I
41 Sqn, Rochford, Supermarine Spitfire F.Mk.IV
Debden Sector
17 Sqn, Hawker Typhoon F.Mk.I
71 Sqn, Hawker Typhoon F.Mk.I
501 Sqn, Debden, Hawker Typhoon F.Mk.I

RAF Bomber Command allocated the following units as Red Forces;
No 2 Group
Marham Wing
105 Sqn, DH Mosquito B.Mk.I
107 Sqn, DH Mosquito B.Mk.I
110 Sqn, DH Mosquito B.Mk.I
139 Sqn (Jamaica), DH Mosquito B.Mk.I

No 3 Group
RAF Marham
115 Sqn, Bristol Buckingham B.Mk.I
RAF Mildenhall
150 Sqn, Vickers Wellington III
75 Sqn, Mildenhall, Vickers Wellington B.Mk.IV

No 4 Group
RAF Linton-on-Ouse
90 Sqn, Vickers Wellington B.Mk.IV
199 Sqn, Vickers Wellington B.Mk.IV

Here I shall explain the features of the RAF defences of the United Kingdom. As a whole they form an interconnected defence network probably unparalleled in the world and operational since 1938.
The first element is the Radio-Location stations, known to the British as Chain Home and Chain Home Low. These consist of long-range and low-altitude systems respectively of over lapping coverage which extends from Southern Wales to Northern Scotland. The Chain Home Low can detect targets as low at 500 feet Chain Home has a range that extends almost to the Hague in the Netherlands and over Northern France, including the entire Cherbourg Peninsular. The Chain stations report their data back to the Group Headquarters of Fighter Command (Groups 10, 11, 12 and 13) and the central Fighter Command Headquarters at Stanmore. Air Marshal William Sholto Douglas is the current commander of Fighter Command. Each of the Groups of Fighter Command cover a geographical location, No 12 Group covers the central portion of England from Cambridgeshire and Norfolk up to the North Yorkshire Moors and westward as far as Wales. Feeding into this system is a network of Observer Corps stations across the country which fill the gaps between Radio-Location coverage, mainly indemnifying enemy aircraft as the cross the coast to classify them by type and to catch low-level enemy aircraft operating under the effective ceiling of Chain Home Low. The Observer Corps are all part-time volunteers and many of them are ex-servicemen. In wartime they would be formed as a permanent unit of the defence network. The Observer Corps is also split into Groups and Sub-Groups and these regional Headquarters feed the RAF Group Headquarters. Acting on information from Fighter Command Headquarters at Stanmore, which has a national air defence picture, and its local Chain stations and Observer Corps units, the Group Headquarters issues orders to the RAF fighter squadrons and Army Anti-Aircraft units in its area of responsibility. Each RAF Fighter Command Group is further sub-dived into Sectors, each having its own Sector HQ which controls the fighters directly. Therefore during the first day of the Exercise we were witnessing the operations of the Headquarters of No 12 Group, Fighter Command at RAF Watnall. It passed its orders down to the Duxford, Coltishall and Wittering Sectors which directly controlled the fighter sorties using data supplied from the command chain and reporting further data back to the command chain. The entire network is linked by the Defence Teleprinter Network which was built up from 1938 and expanded to twice the size of the civil network.
Britain does not just rely on Fighter Command, most AA units of the Army are now equipped with gun-laying RDF sets and those sets can be used to cue searchlights for night defence.

Current RDF sets in use are;
Chain Home Type 2: since 1938-40, range of 125-195 miles, 42.5-50.5MHz
Gun Laying Type 1: since 1938, range of 28 miles, 54-85MHz
Gun Laying Mk II: new for 1942 for use with 3.7in AA guns with a 10cm wavelength
Chain Home Low Type 1: since 1939 range of 55 miles, 200MHz
Chain Home Low Type 2: since 1940, as Type 1 but deployed overseas
G.C.I Type 1: since 1939, range of 112 miles, 209MHz
Chain Home Extra Low: since 1941, range of 35 miles
Searchlight Laying: new type in 1942 and based on the Gun Laying Mk II
Chain Home Type: new type in 1942, a mobile Chain Home Type 2 for use in remote locations and as reserve sets

The object of today’s exercises was Red Force was to launch a series of bombing raids against central England with Blue Forces defending. We witnessed the Chain Home plots, and those of the Blue fighters intercepting Red formations. There were few standing patrols, the use of early-warning meant that defending forces can be kept at readiness on the ground. With enough warning intercepting formations can be in place in time to catch the attackers and often are keyed in by RDF data ahead of the enemy. Low-level response poses a threat but some patrols were flown to counteract. The use of ambush tactics meant that large formations of Blue fighters could be scrambled to check decisive large Red formations. The Group HQ controlled the battle, directing the Sector HQ as to what squadrons to send and they in turn sent back data indicating which squadrons were ready or were being refuelled and rearmed by the use of illuminated boards. That way any sector, or Group, of Fighter Command can be reinforced by its neighbour. The underground HQs are well protected (we were told we would be safe from 1,000lb bomb direct hits) and inside the plotting room has a large table (the further down the Command Chain the smaller the map and more local the scope) where the operators keep the plots updated, above are the controllers and Army liaison officers behind glass with rows of telephones. They have an excellent view of the map plotting table and yet work calmly separated from the sounds of the bustle below so they can concentrate on the work in hand. Efficiency is key to smooth operations and the staff seemed well-oiled in their work and at times it seemed effortless. All the time information was flowing back and forth across the exercise area via the DTN the system works well under exercise conditions. Such networks we were told exist elsewhere across the Empire.

Very interesting James, I am sure the USAAF finds this enlightening, and may request that the RAF assist them in setting up their own such system.

If you want to keep it in-house, the USN had pretty much the same sort of systems (with some of their own improvements). There's probably not that much the British can teach the USAAF at this point that the USAAF doesn't already know; it's more a matter of the USAAF wanting to put the knowledge they have to better use.

Just being polite Brock . The Americans can probably figure it out on their own I agree.

Quoted

Originally posted by TheCanadian
Just being polite Brock .

How very Canadian of you!

September 14
We arrived at RAF Duxford, airfield and Sector HQ in No 12 Group, Fighter Command. We were official observers of day two of Exercise Emperor V, the RAF’s annual full-scale aerial defence exercise.
The Duxford Sector comprises the following units;
19 Sqn, Supermarine Spitfire F.Mk.III
56 Sqn, Hawker Typhoon F.Mk.I
266 Sqn, Supermarine Spitfire F.Mk.III
609 Sqn (West Riding), Hawker Typhoon F.Mk.I

We had a chance to mix with the pilots and ground staff of the airfield and look over the aircraft. The Supermarine Spitfire is well known, the Mk III is an older variant dating back to 1939, powered by a Rolls-Royce Merlin V with a two speed supercharger and an armament of two 20mm Oerlikon cannon and four .303in Browning machine-guns. The Hawker Typhoon also entered service in 1939 powered by a 2,180hp Napier Sabre II and armed with twelve .303in Browning machine-guns with a top speed of 405mph at 18,000 feet.
We were observing from the Sector Control room, a much smaller affair than the Group HQ, basically a reinforced building with a plotting table and the staff and liaison officers sat on a wooden pedestal overseeing the operations. It is a much closer and rawer experience and we were able to listen into the VHF radio sets carried by the fighters.
The Fighter Controller is in charge of directing the squadrons onto the target formations and of updating them with all the relevant changes in direction and altitude. Today his codename was Flapper.”
“Flapper Control calling Buster. Flapper Control calling Buster. Do you read?”
“Buster here, go ahead Flapper”
“Flapper Control. Twenty-plus bandits south-east of you, south-east, angels one-eight heading due west, they should be to your left, slightly below. Over.”
“Buster to Flapper. Can’t see anything. Keep your eyes open boys, should be to port. Still can’t see em’ Fred old boy.”
“Flapper Control to Buster. Bandits should be one mile away, down sun of you. One mile.”
“Tally-Ho Skipper, Wellingtons to port, about thousand feet below.”
“Buster to Flapper Control. Tally-Ho. Am engaging Bandits.”
“Buster Leader here, follow me chaps. Blue Two stick with me. Keep look-out for fighters chaps.”
“Keep close Blue Four”
“Teddy you twit get out of my way!”
“Green Four here, I’ve got one!”
“Watch your tail!”
“I’ve got one!”
“Bandits! Bandits!”
“Where?”
“Buster Leader. Report!”
“Green Three, twelve Hawkers, angels one-two”
“I see them. Green section follow me.”
“Ok Terry.”
“Blue Four cover me.”
“Green Three break! His on your tail!”
“Break!”
“I’ve got one.”
“Break!”
“Someone get him off my tail!”
“Green six you’ve a bandit on your tail!”
“Hang on”
“Get clear you fool!”
This went on for a few minutes, on the plotting table one of the WAAF plotters placed a fresh block of wood onto the map.
“New formation Sir, ten-plus bandits approaching Humber Estuary, about forty miles offshore, heading inland, speed 300 at 500 feet.”
The controller instantly weighed up the situation, quietly conferred with his deputy and then picked up the telephone.
“Control here. Scramble. Scramble.”
He then picked up his microphone.
“Flapper Control to Buster. Flapper Control to Buster. You’ve had enough fun, return to base. Return to base.”
“Buster to Flapper. Wilco. Buster Leader to all sections, return to base. Pack it up lads.”
As he finished speaking the Typhoons of 56 Sqn were already taking-off.
“Flapper Control to Bulldog. Flapper Control to Bulldog. Bandits approaching Humber Estuary, fly bearing oh-fifteen, ten-plus bandits speed three-hundred at angels zero-five.”
“Bulldog here. Roger. Sounds like Mossies.”

This went on for most of the day, by the later afternoon each of the pilots had been up twice, some as many as four times. The USAAF officers swapped stories and gained an insight into current RAF tactical thinking. In particular Squadron Leader Douglas Bader was most impressive when he discussed the evolution of his “Big Wing” theories of using between three and five squadrons as a single entity to intercept large enemy raids. In the early evening Maj. Masterton flew several circuits in a Hawker Typhoon at RAF Duxford in order to make a brief appraisal of the type. His report on the G.40 and Typhoon is attached under Annex C.

September 15
We arrived at Anti-Aircraft Battery 44, 36 Brigade, Anti-Aircraft Command. We were official observers of day three of Exercise Emperor V.
The Anti-Aircraft forces for the defence of the United Kingdom are under the command of Anti-Aircraft Command currently under the command of Lt. General F. Pile. These units though are part of the Royal Regiment of Artillery (RA). The overall network of the batteries is a nucleus in peacetime covering certain key areas and in wartime the hubs of the nucleus would be fully formed with other units. The largest formation is the Regiment of Heavy Anti-Aircraft Artillery. This comprises a HQ Staff and three batteries of eight guns each, split into two four-gun troops. Ammunition per gun is 250 rounds.
The battery we observed was equipped with the standard Ordnance QF 3.7in Mk IV. This weapon entered service 1937 in its Mk III form. Weight in action is 17.1 tons static, effective ceiling is 32-45,000 feet and ground range is 20,600-25,600 yards. Rate of fire is 25 rpm on the mobile mount and 19 rpm on the static mount (Mk III). Elevation is 85 degrees on the mobile and 90 degrees on the static mounts. The Mk IV we witnessed was introduced in 1941 and has totally new ancillary equipment, the new Machine Fuze Setter No.11, and an automatic loader which raises the rate of fire to 20 rounds per minute.
The battery was also equipped with the brand-new Gun Laying Mk II RDF set. This was only introduced earlier this year for use with 3.7in AA guns and it has a 10cm wavelength. The system has a transmitter and receiver display in separate trailer cabins. The transmitter is a pair of air blown triodes operating at 5 K volts, the modulator is a blocking oscillator which operates at about 1500 c/s, and the pulse of about 1mS duration is determined by the blocking oscillator grid capacitor. The short duty cycle puts a power limitation (about 0.25 MW) on the space charge of the filaments. The Lecher line tuning is push pull. Both the transmitter and Receiver/Display Unit are mounted in cabins, which are rotatable on the travelling trailer chassis via bicycle pedals hand operated linked by chain to the cabin turning gear. The receiver uses TV RF receivers, tuned to around 60MHz followed by an IF at 15MHz. All the RF and IF valves are EF50 pentodes. In a surrounding metal can they carry their own screening and have screw on retaining rings. There are five aerials, the highest having a reflector that can be shorted at the centre. The change of signal strength (with and without the reflector) allows the right polarity of direction to be determined. The four operational aerials are horizontal dipoles in a flat vertical array mounted on outriggers turning with the cabin, and have a narrower beam (about 20 degrees) than a simple dipole. The array has a vertical lobe pattern complicated by the ground reflection. Signal balance (upper and lower) is effected by a cam operated goniometer, between upper and lower aerials, so that maximum signal from the target is obtained at the correct azimuth setting. The British electronics company Cossor has developed a new display bolted onto the front of the display unit. It consists of two five inch display tubes, for bearing and elevation. The time base is a pure exponential charge on a capacitor, of a voltage nearly equating the tube supply, and the equally large X shift potential required to bring the spot back centrally is obtained from a hand-wound, oil-filled exponential-law potentiometer. The sight is exponential, since the law is accurately predictable and repeatable. Range is measured from the hand operated rev. counter, which turns the exponential X shift pot. All data is sent automatically to the predictor via mag slips (Selsyns), the guns are laid via mag slips and oil motors by the predictor. Selsyns is a trade name for a rotary device with a three phase field. The rotary pick-up coil of the transmitter version passes on a signal, whose phase is an indication of the position of the rotor. The receiver is an indicator that sets itself to a position where, by cancellation with the transmitted signal, there is no residual flux giving torque to the rotor. Bearing is established by rotating the cabin, using the hand-operated pedals, until the split bearing signals match for amplitude, and also the split elevation signals using the cam-operated goniometer. The control of the latter is a linear handle rotation, and has a shaft protruding from the side of the cabin, which can mount a telescope used to sight a balloon carrying a reflector when the station is being calibrated. To ensure best standardisation of ground effect on the aerials, permanent sites have a mattress of wire netting, mounted on short stakes, over the area of the site of about fifty yards in diameter, unbroken except for a walkway to the cabins.

Live firing trials against six de Havilland Queen Bee drones resulted in six kills. With blanks employed against attacking formations the accuracy was quite impressive and there was no doubt that the system works and would be deadly against large four-engined bombers within its effective ceiling and range. Using such equipment also gives an excellent night defence as well as its able to be just as accurate in putting up barrages. Its use in slightly modified form to direct searchlights (such a set was also used by the battery) offers flexibility in directing light beams onto targets for laying non-RDF equipped batteries onto such targets and for visual confirmation. It can only be a matter of time however before the searchlight is rendered fully obsolete by RDF-laid batteries.

Later in the afternoon we went to RAF Marham to witness the de Havilland Mosquitos of No 2 Group, Bomber Command prepare for their sorties. Here the Marham Wing of 105, 107, 110 and 139 (Jamaica) squadrons form a potent fast bomber attack force. Some of their sorties have been flown as low as twenty feet over the sea to evade Chain Home Low stations and with speeds above 300 mph at that level they have proved hard to intercept. At altitude they too have a speed advantage but low-level work is probably more profitable. The lack of defensive armament hasn’t been felt as a drawback. The pilots could not wait to gain new Mosquitos with heavy nose armament for ground strafing attacks. Witnessing a group of experienced pilots beating up the airfield for our benefit at very low level we couldn’t but be impressed how deadly such an attacking force could be. Whether we could operate our new A-26s that low is open to question. Also at RAF Marham are 115 Squadron of No 3 Group, Bomber Command. They operate the Bristol Buckingham medium bomber, a type felt by many to be eclipsed by new fast bombers like the Mosquito but an aircraft that offers the best characteristics of our own B-25 and B-26 fleets. It is well armed and is fast enough for modern aerial combat; certainly it seems far more capable than the older Vickers Wellingtons that still remain in Bomber Command service. The rationale of the RAF seems to be to focus on the Mosquito in Britain and to have the bulk of the Buckingham fleet overseas where its excellent 3,000 mile range can be put to full use and its defensive armament and performance can surpass many of the likely fighter and anti-aircraft threats overseas.

September 16
Return to Southampton by train to embark on PanAm Clipper flight at 108 Berth, BOAC Terminal for flight home. The British reception committee, including Secretary for Air, John Moore-Brabazon saw us off and we exchanged a few last minute notes and words. Brabazon presented me with a scale replica desk model of the Whittle W.1A turbojet engine.