D.H.88 Comet Follow-Ons

[apophenia]

Fast Air Mail - the de Havilland D.H.88 RM Comet Mailplane

After a highly successful showing in the 1934 MacRobertson Race, there was great interest in de Havilland's twin-engined D.H.88 Comet racer. The French government bought one of the three racers - G-ACSR which was modified as mailplane F-ANPY. The French then ordered another Comet, F-ANPZ, built from the outset with a mail compartment in its nose. Not to be completely outshone, the Royal Mail belatedly followed suit. In early 1936, four purpose-built D.H.88 RM Comets were ordered from de Havillands.

In general configuration, the General Post Office's Comets were similar to France's F-ANPZ. The racer's 128 Imperial gallon fuel tank was deleted and replaced by a hinged-top forward-fuselage mail compartment. Although advised to make minimal changes, the General Post Office slowed delivery with modifications. For its 'Domestic' variant - the D.H.88 RM 'D Type' - the GPO insisted on omitting the navigator's position in favour of an increased mail capacity. This would prove unwise ... beyond incurring delays.

Another result of 'D Type' modifications was that the less-heavily modified 'Airmail' variant - the D.H.88 RM 'A Type' - would be delivered to the GPO first. The D.H.88 RM(A) remained a two-seater. For longer-range international airmail flights, the navigator was deemed essential. This reduced mail capacity by 120 lbs - the 'A Type' having no aft mail compartment'. However, pilot's generally regarded the D.H.88 RM(A) as having better handling than the single-seat 'D Type'.

Top De Havilland D.H.88 RM (A Type) Comet mailplane, G-ARML. The swiveling tailwheel was part of a 1938 upgrade programme.

Royal Mail livery for the Comet was all-over 'pillar box' red except for a black 'cheat line' along the top of the nose. [1] Markings consisted of the Royal Cypher and 'Royal Mail' titles in gold on the nose; British registration letters in white; and the Royal Mail Lines pennant on the tail fin. [2]

GPO Comet mailplane service began in the Summer of 1936 with G-ARML. After proving flights to Paris and Brussels, the first 'operational' flight was made from Croydon to Lisbon where 'late post' was delivered to the Royal Mail Lines' RMS Asturias before she steamed off to South America. [3]

With a range of just under 1,300 miles, the D.H.88 RM(A) had less than half the reach of the Comet racers. However, this was more than adequate for 'Continental' airmail routes. Lisbon was a 985 mile flight from Croydon. Most routes were flown in stages. The longest was the UK-Egypt route which was normally flown in four stages - Marseilles (625 miles); Bastia (Corsica, 204 miles); Malta (515 miles); and Alexandria (955 miles). The object of this routing was to avoid Italian airspace forbidden to British-registered aircraft. A variation on the UK-Egypt route was Croydon- Paris-Bastia-Malta-Alexandria. Other, locally-based aircraft flew the airmail on to Cairo for distribution.

While the international routes were considered a success - and a boon to British prestige - the 'Domestic' variant was another matter. Demand for 'internal' airmail proved quite limited - in most cases, rail delivery being almost as fast. After a few trial flights, D.H.88 RM(D) G-ARMA was put onto a new Croydon-Dublin route. By the Summer of 1937, the Dublin service was abandoned. G-ARMA was then used as a dedicated courier service for diplomatic mail to Berlin (580 miles from Croydon) and Rome (890 miles). These 'diplomatic pouch' flights continued until the Autumn of 1938 when Imperial Airways took over this service.

Top De Havilland D.H.88 RM (D Type) Comet mailplane, G-ARMA. Note the single-seat cockpit, rear fuselage hatch for additional mail, and revised cowlings. Also visible here are the DH-licensed Hamilton-Standard propellers distinct to the 'Mail Comets'. These metal-bladed, variable-pitch Hamilton-Standard types replaced the Ratier props used on earlier Comet.

Experience with the 'D Type' G-ARMA convinced the GPO board that the second airframe should be completed as a more utile D.H.88 RM(A) model. As a result, three 'Airmail' variants were built - G-ARMB (begun as a 'D Type'), G-ARMK, and G-ARML. Ironically, the 'Domestic' role was reprised during WW2. All three 'A Types' were employed delivering priority war correspondence around the British Isles. Although not impressed by the RAF, the wartime Comets worn khaki paintwork. The sole 'D Type' was robbed of parts to keeps its siblings flying. This fairly thankless tasking was also a hard slog. None of the 'Mail Comets' would survive the War.

_______________________

[1] This 'cheat line' is sometimes mis-characterized as an 'anti-glare' panel. In fact, this paintwork was gloss black.

[2] Technically, the GPO's Comets fell under the control of the Royal Mail Lines Ltd.

[3] This allowed RML ships to take on mail posted 2 days after the vessel had left Southampton. Flying time to Lisbon at 220 mph was only 4.5 hours (although aircraft sometimes stage through Bordeaux). In this way, post from both the UK and Portugal could be delivered via RML to Brazil, Uruguay, and Argentina.

[elmayerle]

Very tasty!!  Lead me not into temptation.

[GTX_Admin]

 

[GTX_Admin]

I am tempted to do a RAF one.  Would probably be armed with 1 20mm cannon and a pair of .303 MGs.  Idea would be for it to play the role of long range/long endurance 'heavy' fighter alongside the likes of the Gloster Gladiator. 

[robunos]

GPO Comet mailplane service began in the Summer of 1936 with G-ARML. After proving flights to Paris and Brussels, the first 'operational' flight was made from Croydon to Lisbon where 'late post' was delivered to the Royal Mail Lines' RMS Asturias before she steamed off to South America.

Of course, if the overseas version was floatplane, the floats could carry the displaced fuel, restoring the range, and the aircraft could alight in the harbour. or even deliver the mail to the ship while at sea, conditions permitting . . . 




cheers,
Robin

[apophenia]

Very tasty!!  Lead me not into temptation.

Sorry Evan. 'Lipstick Red' is temptation, by definition 

Of course, if the overseas version was floatplane, the floats could carry the displaced fuel, restoring the range, and the aircraft could alight in the harbour. or even deliver the mail to the ship while at sea, conditions permitting . . . 

Good points! I did wonder about floats ... maybe extending the route from Alex to Bombay? And there's always the pressing need to show Lufthansa how catapult airmail should really be done!

I am tempted to do a RAF one.  Would probably be armed with 1 20mm cannon and a pair of .303 MGs.  Idea would be for it to play the role of long range/long endurance 'heavy' fighter alongside the likes of the Gloster Gladiator.

Oh no! I can feel an armed Comet variant coming on. Cannot. Make. It. Stop... 

[apophenia]

Sow's Ear or Kindling? - The Fate of the RAF's De Havilland DH.88 Comet

After its success in the MacRobertson Air Race, a single de Havilland DH.88 Comet was purchased by the Air Ministry in June 1935. Formerly 'Grosvenor House' (G-ACSS, c/n 1996), the little racer was repainted painted silver overall and assigned RAF serial K5084. Evaluation of the D.H.88 was performed by the Aeroplane & Armament Experimental Establishment (A&AEE) from RAF Martlesham Heath. However, in September 1936, K5084 was written-off in a heavy landing at Martlesham Heath. In this accident, the Comet's undercarriage collapsed and the fuselage of was ruptured as the main fuel tank broke free.

Seeing no real military role for the delicate D.H.88, the Air Ministry recommended selling K5084 for scrap (estimated value being between £200 and £350). However, some A&AEE staff advocated rebuilding the damaged aircraft as a test bed for prone-pilot operation. A basic concept was draughted which involved replacing the shattered forward fuselage with a new prone cockpit section. The original cockpits were to be eliminated, the forward position to be occupied by a new fuel tank.

As sketched, the new prone cockpit would be quite cramped. (Indeed, the position was so tight that some instruments had to be mounted externally - including engine instruments attached to inner cowlings.) The pilot would lay on a 'settee' with a small Perspex 'dome' providing forward vision. It was thought that the view to the sides would be extremely poor but this was judged acceptable for an experimental aircraft. There were small 'porthole' side lights let into the canopy's hinged hood but these were more for illumination than vision.

With rough plans in hand, enquiries were made of de Havilland Aircraft about having K5084. Hatfield was appalled by the A&AEE's scheme and declined to have anything to do with it. The remains of K5084 lay in a shed at RAF Martlesham Heath while the Air Ministry cast about for a 'Plan B'. In the meantime, de Havillands made clear that they had no objection to any modification work being performed 'out of shop'.

(To be continued ...)

[GTX_Admin]

 

[Robomog]

Theres a lot of really inspiring stuff here,   love it !!


Hmmmmm  float plane version thats food for thought.


Mog
>^-.-^<

[Buzzbomb]

Nice work.
The Airfix  Dh-88 must have been one of those kits that nearly every modeller of a certain age must have done at some stage

[GTX_Admin]

Nice work.
The Airfix  Dh-88 must have been one of those kits that nearly every modeller of a certain age must have done at some stage

Nope.

[jcf]

DH.88 PP, the Chiropractic Special.

 

[apophenia]

DH.88 PP, the Chiropractic Special.

"It's just this crick in me neck, Doc ... " 

Nice work.
The Airfix  Dh-88 must have been one of those kits that nearly every modeller of a certain age must have done at some stage

Nope.

"The Airfix Dh-88 must have been one of those kits that nearly every modeller [other than scale absolutists] must have done at some stage." 

[apophenia]

'Plan B' - Arthur Hagg is Reacquainted with his Creation

In early 1936, Arthur Hagg left de Havilland Aircraft to pursue his passion - boat building. [1] Hagg had set up his own shipyard at Walton Bridge near Shepperton in Middlesex. Hagg's new Walton Yacht Works submitted one of its designs to the RAF as a new fast tender type. This seaplane tender concept was awarded a prototype order but this contract came with a 'rider'. The Air Ministry had seen an opportunity to reacquaint Hagg with his most famous aeronautical creation - in the form of the RAF's ruined Comet K5084 airframe.

Renewed design work on the D.H.88 Comet was certainly outside the quotidian for Walton Yacht Works. But Hagg was not averse to further aviation work - indeed, he just become a consultant to D Napier and Son, Ltd. [2] Accepting the D.H.88 assignment meant taking on two distinct redesign contracts. The first was assessing whether the A&AEE's prone-pilot testbed concept was feasible. The second was a study for a much faster, single-engined redesign as a possible land-based mount for a revived RAF High Speed Flight. Hagg elected to address the more challenging, single-engined rebuild first.

The Need for Speed - RAF High Speed Experimental Flight

The new High Speed Experimental Flight (HSEF) was being formed under Squadron Leader Sidney N. Webster, AFC - raised to (T) Wg Cdr for his new command. Whereas its namesake had been aimed at the Schneider Trophy, [3] the new High Speed Experimental Flight would be dedicated to introducing higher-speed flight to service pilots. The thin wing of the D.H.88 suggested its suitability for 'pushing the envelope' on high-speed flight without the compromises of pending service types like the Hawker Hurricane. With his new Napiers connection, Hagg chose the high-powered engine he was most familiar with - the Napier Lion. Although rather dated, the Lion W-12 engine was readily available unlike the still largely experiment Rolls-Royce PV-12 V-12.

Arthur Hagg produced two High Speed concepts fairly quickly. Both eliminated the Comet's underwing nacelles and introduced a single-seat cockpit under a sleek, forward-sliding canopy. [4] The first design represented a near-complete redesign of the airframe. The formerly low-set DH.88 wings were repositioned as mid-mounted. New engine bearers (attached to the undersides of the wings) extended forward to support a geared Napier Lion. Above the wing was a new main fuel tank. Below the wing were attachment points for a new, retractable main undercarriage. A retractable and neatly-faired tail wheel was also introduced.

Hagg's Hotchpotch - Contrasting Comet Concepts

Walton drawing staff dubbed this first design the 'DH.88 (HSH)' - for 'High-Speed Hagg'. The mid-positioned wing allowed the main landing gear to be retracted up into the sides of the lower fuselage. The wings themselves were faired into the cowling extension from the W-12 Lion's lower pair of cylinder rows. This, Hagg had concluded, was the ideal aerodynamic layout for the airframe. The trade-off was in visability from the rear-placed cockpit. The sliding-canopy allowed the pilot to look past the wings (and engine cylinder side fairings). Persepx windows were also let into the fuselage belly to give the pilot some degree of downwards vision.

The second design was regarded as a back-up scheme by Arthur Hagg. The basic low-winged arrangement of the D.H.88 airframe was retained. Powerplant options were the geared Lion offered in the first design or an ungeared derivative of the Sea Lion boat engine (the latter being an attempt at cost savings). Removal of the original wing nacelles presented the problem of how to incorporate a retractable undercarriage. The wing, it was judged, was simply of too thin a profile to accommodate a sidewise hinged main gear. Hagg's solution was to install streamline fairings into which the main legs would retract. This solution paid a penalty in increased drag but allowed for a much simpler style of main undercarriage compared with the first design.

(To be continued ...)

______________________________________

[1] Hagg's former position as Chief Designer of de Havilland Aircraft would be taken over by Ronald Bishop.

[2] This consulting was as much about maritime applications for Napier's Sea Lion W-12 engine. However, Hagg would also later be involved in the preliminary design of the Sabre-powered Napier-Heston Racer.

[3] Based at RAF Calshot seaplane base near Southampton, the original RAF High Speed Flight had been disbanded once the Schneider Trophy had been secured in 1931. The new High Speed Experimental Flight would be land-based at RAF Martlesham Heath in Suffolk.

[4] In aerodynamic form, if not construction or operation, the shape of this canopy anticipated Hagg's work on the later Napier-Heston Racer.

[jcf]

DH.88 PP, the Chiropractic Special.

"It's just this crick in me neck, Doc ... " 

Nice work.
The Airfix  Dh-88 must have been one of those kits that nearly every modeller of a certain age must have done at some stage

Nope.

"The Airfix Dh-88 must have been one of those kits that nearly every modeller [other than scale absolutists] must have done at some stage." 

"The Airfix Dh-88 must have been one of those kits that nearly every modeller in the English speaking world outside of the US [other than scale absolutists] must have done at some stage." 
 

[apophenia]

Fair comment     Now here's another 'Chiropractic Special' ...

'Haggiography' - Lying Down on the Job in Walton-on-Thames

The first part of Arthur Hagg's D.H.88 assignment had been to assess the feasibility of the A&AEE prone-pilot testbed concept. was feasible. This too was aimed at the new RAF High Speed Experimental Flight - not because such a design was expected to be especially fast but, rather, to determine the value of prone-pilot positions in future high-speed aircraft. By the time Hagg and his Walton Yacht Works team had turned their attention to the prone-pilot testbed, the HSEF was already losing interest in Hagg's genuinely high-speed proposals. [1] Regardless, Hagg's prone-pilot proposal owed something to the first of those single-engine conversion proposals.

Like the first single-engined concept, Hagg's prone-pilot proposal raised the original D.H.88 wings to a mid-fuselage position. There the similarity ended. Other than this wing repositioning, the Hagg proposal followed the A&AEE's prone-pilot concept quite closely. An obvious difference was that pilot's legs now lay below the wing centre section. The fuel tank above the raised wing was necessarily small. However, this was not seen as a problem as longer flights were not meant to be part of the A&AEE test programme. The Air Ministry accepted this proposal - as the D.H. HSP (for High-Speed Prone). Again, the terminology reflected use by the HSEF rather than an anticipated high speed.

Top Arthur Hagg's D.H.88 prone-pilot conversion as originally proposed, October 1937.

Model-makers at Walton produced a 1/18th scale test article for wind tunnel trials. The 24 foot low-speed wind tunnel at Farnborough produced some unanticipated results. Raising the wings obviously also raised the engines' thrustline. Unfortunately, scaled testing at Farnborough revealed that the resulting propeller wash was likely to create tailplane flutter. The only solution was to redesign the tailplane to raise the D.H.88's stabilizers and elevators up out of this propeller-generated turbulence. Fortunately, this could be accomplished through modifying existing components. Hagg also took the opportunity to refine the tail cone and introduce a tailwheel for better ground handling.

Bottom Revised D.H.88 (HSP) 'Prone Comet' conversion as completed, January 1938.

Actual modifications of Comet K5084 airframe components were completed fairly quickly at Walton. Those components were assembled at RAF Martlesham Heath in late January 1938. With ground checks finished, testpilot Flt Lt H.M. Schofield took the rebuilt 'Prone Comet' into the air early on Thursday, 10 February 1938. [2] In his assessment, Harry Schofield ranked flying characteristics to be as good or better than the standard D.H.88. Visibility during take-off and landing were gauged of "an order of magnitude improvement" over the restricted sightlines from the standard, rear-cockpit Comet. The choice to go with a prone-pilot conversion of K5084 were vindicated.

The rebuilt Comet provided a wealth of test data on prone-position flying. Most of this test work was performed by Sqn Ldr D'Arcy Greig, DFC. [3] It was Greig who was at the controls of K5084 when it experienced an uncontrollable engine fire in flight on 13 June 1938. Greig was forced to take to his parachute over Gedgrave Hall. The burning aircraft came down in the North Sea off of Orford Ness. Settling in over 60 feet of water, no attempt was made to recover the wreckage of the D.H.88 HSP.

__________________________

[1] It was now concluded that service aircraft like the new Hawker Hurricane fighter would be more than adequate to meet the needs of the RAF High Speed Experimental Flight. By the time that either of the single-engined Hagg proposals could be finished, sufficient Hurricane fighters would be available to spare some for HSEF use.

[2] HSEF commander, (T) Wg Cdr Sidney Webster, had convinced RAF Reserve officer and former Schneider Trophy pilot, Flt Lt Schofield, to take on HSEF test pilot duties. Harry Schofield took unpaid leave from his employers, General Aircraft Ltd., to perform this work.

[3] D'Arcy Greig was another veteran of the original High Speed Flight. Now-Sqn Ldr Greig was seconded to the HSEF on leave from his CFI duties at the Central Flying School at RAF Upavon, Wilts.

[apophenia]

No backstory on this one ... just wanted an excuse to do Robin's mailplane-on-floats concept 

[Robomog]

Inspired ! 

Thats  one for the things to do book 

Mog
>^-.-^<

[robunos]

Ooohh !!  Me Likey Lots !!   
Supermarine S.5 floats ? The lower one looks better, though I suppose the extra ventral fin would be more accurate . . .   
A further thought, would this need handed engines ? And just to push this even further, combine your Lion powered version with this floatplane, to make a trainer for Schneider Trophy pilots, in a competition that didn't end in 1931 . . .   


cheers,
Robin.

[GTX_Admin]

 

[apophenia]

Thanks folks. Well-spotted Robin, they are indeed S.5 floats (even kept the floats' racy paint scheme, though not the colour).

Agreed on the ventral fin aesthetics ... but all floatplanes seem to end up sprouting additional tail surfaces. Although, if she'd been given handed engines, maybe not?

I did toy with a single-engined Comet derivative on floats but it looked waaay too Schneider-y. But, I'm pretty sure that there is a racer on its way 

[robunos]

Always did have a thing for the Schneider Racers, specially once I found out Sidney Webster came from my home town . . . though unfortunately the Local Authority don't do anything to celebrate this, doesn't fit their agenda . . .       


cheers,
Robin.

[apophenia]

Always did have a thing for the Schneider Racers, specially once I found out Sidney Webster came from my home town . . . though unfortunately the Local Authority don't do anything to celebrate this, doesn't fit their agenda . . .

Hmm, sounds like local enthusiasts need to go around the council. Instead of an appeal to authority/tradition, perhaps more of a 'Local git makes good' approach? Some organization/private entity which would benefit from some publicity would seem an obvious conduit.

A local news search tells me that the Park Place Shopping Centre is closing its entire upper floor and is need of an update. To my eyes their glassed-in, 2-storey escalator alcove needs a plaque and a large-scale model of the S.5 hung from its ceiling   

[robunos]

TBH, I can see Park Place being closed down and 're-developed' . . . If it was up to me, there'd be a statue of Webster on the Bridge, opposite Sister Dora, instead of the useless fountain, or if not there, in front of the Town Hall and Library, with John Carless VC, and the Hippo, and a replica S.5 on the roundabout at the junction of Lichfield Road and Mellish Road, which isn't far from his birthplace in Borneo Street, similar to the E.28/39 replica in Lutterworth. Or even an 'artistic' design like the Spitfire Island in Castle Bromwich, Birmingham . . .


cheers,
Robin.

[apophenia]

As promised, a racer ... sorta.
_________________________

In 1938, the Admiralty had become interested in an engine in the size-range of the 'R' racing engine. This led to the Rolls-Royce Griffon - an entirely new V-12 which had been influenced by the PV-12 Merlin but was dimensionally similar to the older 'R' types. The Admiralty envisioned the Griffon powering a new generation of 2-seat fighters and strike aircraft.

The Navy was well aware of the RAF's Speed Spitfire (Supermarine Type 323) project, intended for an attempt on the FAI world speed record. That record stood at 379.63 mph established in November 1937 by a modified Messerschmitt fighter - the Bf 109 V.13. But that speed had been exceeded at low level (400 m) by an 'R' powered Supermarine S.6B floatplane racer back in 1931. [1] The Admiralty decided to commission a thinly-disguised record attempt aircraft - the so-called Griffon 'Experimental Engine Demonstration Aircraft'. Since Supermarine was already committed to the Speed Spitfire, the contract for a Naval 'EEDA' went to de Havilland Aircraft.

Known internally as the 'Admiralty Racer', for record-keeping purposes, the DH.108 'EEDA' was referred to as the 'Comet AR'. In reality, the DH.108 had virtually nothing in common with the twin-engined DH.88 Comet racer of half a decade earlier. There were similarities in construction, however. The 'Comet AR' airframe was made almost entirely of wood. This was partly to speed creation but de Havilland was also convinced that the smoothest possible airframe could only be created from rivetless wooden construction. A wooden airframe for a one-off experimental aircraft may also have appeared less suspicious to any prying Air Ministry officials.

The DH.108 was a mid-winged aircraft with the cockpit situated well aft. Those wings were three-spar structures related to the DH.88 wing but with a modern, thicker NACA section and almost 10 feet less span. The fuselage was a moulded plywood form of somewhat complex shape to accommodate the massive radiators needed to cool the large 'Griffon R' powerplant. When retracted, the main wheels of the undercarriage were accommodated in the lower fuselage sides. The tail skid retracted flush to the rear fuselage.

It was intended that current record-holder would pilot the 'Comet AR'. Technically, S/L George Stainforth, AFC, was commanding 802 Naval Air Squadron but any 'experimental' flying would also be done on behalf of the Fleet Air Arm. Accordingly, S/L Stainforth was to be seconded to a new EEDA Flight based at Abbotsinch. As it happened, the speed record was raised by the Germans to more than 469 mph in April 1939. Despite doubts of being able to match that speed, it was decided to proceed with the DH.108. If the new speed record could not be broken, the Royal Navy would simply reveal the DH.108 as its 'Experimental Engine Demonstration Aircraft'. The first flight was planned for early October 1939, but this was not to be ...

_____________________________________

[1] The top speed of the S.6B was 407.5 mph, establishing an Absolute World Speed Record on 29 September 1931