Bletchley

Yesterday I picked up a copy of this classic WWI flying book for £1, and as I already have the later hbk edition I do not need it, but thought someone here might like it. It is a copy of the 1966 pbk Mayflower edition - in very good condition (clearly been sitting o a bookcase for the last 40 years) as the rather poor quality paper is starting to go yellow with age, but the edition is otherwise in fine condition - not at all dog-eared, no pages missing, not falling apart. This is essentially the same as the revised 1971 edition, but without the photographs. It is the first revision of the original 1933 edition, with the escape narrative cut out but with the expanded ending of the later 1971 edition. A good reading copy rather than a collector's item. I will sell it to the first OFFer posting here, at cost price of £1, plus the cost of postage to anywhere in the world. It it is a slim paperback, the size of a DVD case, and not much heavier - so the postage should not be too much, even airmail (but I won't know how much until I send it, as it depends on where you are). I can accept Paypal payments in £ or $US or Eur. So, first to post here gets it :) Bletchley

Yes, you are the first, Rugbyfan - in the post to you Monday, and I will send you a Paypal notification for £1 + postage when I know what the postage is going to be. Bletchley

Hello Chris/Rabu, I don't have any more at the moment, but I am constantly on the look out for maps that would be suitable for OFF - the main problem is that modern repro. maps, or maps from the Web, are mostly copyright. The original maps are out of copyright now, but it is difficult to find the right small-scale maps that they would have used for air navigation (mostly 1:40,000, 1:100,000, 1:250,000) as these were made in much smaller numbers than the large-scale Trench maps (1:10,000), and fewer have survived (see my article on WWI mapping in the WWI Archive section of this forum). Those that have survived are mostly in historical map collections and museums. We really need a friendly map collector.... But if I find any more, I will send them to you, Rabu, for digitization :) Bletchley

It probably was Archie, Jim :) The first barrage was generally the most accurate - the gunners had the time to make careful calculations of height, speed and direction before the target aircraft started to make evasive moves. If there was cloud in the sky they could get good altitude and wind-drift information from those in advance (and flying into a cloud to evade AAA fire was often, therefore, the worst thing a pilot could do). I have read reports in the memoir literature of pilots seeing another aircraft, no enemy in sight, just explode for no apparent reason - but it usually turns out to have been an accurate first salvo from AAA. Or it could be a leaking fuel tank? But I am not sure if OFF models explosions from this - I have had several leaks now, but the fuel just seems to leak away until the engine stops. Bletchley

Since writing the article that tttiger refers to above (quite a long time ago) I have been able to look closely at further data sources, for French and German as well as British, and can say with some confidence that pilot losses to AAA were approximately 8% to 9% of the total combat losses (this excludes losses as a result of accidents). This means that out of 100 pilots lost in combat, 8-9 were lost to AAA, and a similar number were lost to ground fire. This is an average for the whole period of the war - there were obviously peaks and troughs, and seasonal variations. I don't have any problems with the current AI Gun Fire (Range) settings, as they can be varied. They seem about right to me, so far. I have seen aircraft shot down on the easy setting, and the AAA seems deadly enough on the hard setting. I have been flying with the "easy" setting in 1915, and the "normal" setting in 1916-1917. The flak bursts seem to me to be reasonably grouped - I can usually get a good general idea of where the e/a are from the bursts, even on "easy", and I doubt if they could be grouped any more tightly without making them also more effective. I think the setting also effects the range at which AI pilots open fire, so keeping the setting to easy-normal prevents the kind of accurate long-range mg fire from AI pilots that have been complained about in the past. I am still getting a feel for it in the later years of the war (I have been flying mostly 1915/16), so the "hard" option is still there if "normal" starts to feel too inneffective in the later war period of 1918. Bletchley

Hello andqui, I don't know much about the German or French systems. The prevailing view appears to be that German pilots had to go on until they dropped, but were transferred to elite units if successful (i.e. they had nothing resembling the 'tours' of duty established by the RFC). Maybe they had a period of home leave between transfers? I guess leave would otherwise have been handled in a similar, way with pilots taking their turn in rotation. Maybe they also had some sytem of rewarding success, with periods of leave from the Front in order to be invested with medals or to be promoted to the press, or to 'protect' the highly publicised aces? (I seem to recall that they tried to keep MvR from returning to combat duties for this reason, although I may be wrong about that). I know even less about the French system, but I would guess it would have been more like the German system than the British. Both the French and the Germans appear to have had a culture whereby the 'aces' were promoted to the press and concentrated together in elite units, whereas the British liked to maintain their anonimity (with some exceptions) and spread them around more. The British system of having 'tours' of duty helped to do this, but would probably not have worked so well with the French or German systems. Bletchley

Hello andqui, In the RFC there were usually two pilots away on leave at any one time, in quiet periods (leave was usually cancelled, I think, when an offensive was imminent), and this was managed in rotation (so, about one period of leave every two to three months). The normal leave period was 10-14 days for home leave, to allow for travelling time, but there were also shorter periods of one week or a weekend to allow for breaks in Paris, or just for rest (at the discretion on the CO, I think, and probable only in quiet periods as well). A normal 'tour' of duty for an RFC pilot was 6-9 months, but there was some discretion here also, exercised by the CO and the Medical Officer, and it would depend on how much flying/combat the pilot had experienced and any symptoms of combat fatigue or altitude sickness (often ear or sinus problems, or recurrent headaches) - a pilot arriving in a quiet period, usually in late Autum or Winter, could expect to stay somewhat longer than 6 months, whilst a pilot arriving in the Spring or Summer would most likely be sent back to Home Establishment in the Autumn or early Winter of that year. A pilot sent back to Home Establishment would either join a Training Squadron as a flying instructor, or a Home Defence Squadron. These postings were usually for about 6 months, and the pilot would then be posted back to the Front (usually to a different squadron, and with promotion to Flight Commander). An RFC pilot from Canada, Australia, South Africa, etc. would usually have the option of 'Home Leave' instead of Home Establishment, and this might be followed by a stint as a flying instructor in the home country. After surviving a second 'tour' the pilot would normally be posted to a permanent training or staff post, or in some cases the command of a squadron (but squadron commanders were not expected to fly very often, if at all, on combat patrols). I am not sure if this was ever made official policy, or if it just evolved, and there were probably variations on this from one unit to another, and from the early period through to the late period of the war. Bletchley

If I arrive at the airfield and it is raining or snowing, then I go back to the Mess and advance time - and keep on doing that until the weather improves somewhat. Bletchley

Yes, if remains can be identified then the relatives/descendants can be notified. Like Beanie, my great-uncle died on the Somme in 1916 and is one of those simply named on the Thiepval memorial, with no grave or headstone. My grandmother, his sister, spent a long time after the war trying to gain any definite confirmation, or just more information, of his death. We are lucky, as my father persued this later in his life and we now know roughly where, when and how he died - but for many others, they are still just 'missing, presumed dead'. Bletchley

Great work! Thank you Rabu, Chrispdm1 and OlPaint01 :) The map now looks very similar (and on a similar scale, now that Rabu has enlarged it) to those 1:250,000 scale (aprox. 4 miles to the inch) maps that would have been the main type of map used by the RFC. Other scale maps would also have been used - 1:100,000, 1:40,000, 1:20,000 - but these would have been only available for front-line areas within 30 miles or less either side of the lines, until late 1918 (and Rabu has reproduced some of these as well). The French used a black and white hachured 1:80,000 scale map, the Germans used a 1:100,000 scale map. All of them were based mainly on the original French mid-nineteenth century 1:80,000 mapping of France, often just enlarged and redrawn, and so the originals would also have had plenty of errors - roads and railways that weren't marked on the map, changes to size, shape (and even sometimes location) of many of the urbanised or industrial areas. So don't get too hung up on the differences between the map and the actual lie of the land - such errors and differences were there in 1914-18 as well, as the highly accurate maps we use and take for granted today are a relatively modern invention. Bletchley

Aviation Maps and The Small-Scale Mapping of the Western Front If you mention "World War One" and "Maps" the mind is instantly drawn to the prodigious number of large-scale (1:10,000 or less) 'trench maps' of the opposing trench systems that were the result of the gradual and painstaking survey and re-survey of the front-line areas by the field survey units of both sides, from the Spring of 1915 onwards. These maps were drawn and printed in their thousands, and were frequently revised and overprinted, with millions of individual map sheets being distributed to the armies on the ground: a total of 34 million sheets by the British, 33 million by the French and a staggering 775 million by the Germans (Chasseaud). There is a good deal of information out there on these trench maps, which were often carried home by demobilised soldiers and, although fragile, have survived in enough numbers to become collectors' items. McMaster have a wide selection of these that can be viewed online here: http://library.mcmaster.ca/maps/ww1/home.htm and for those who would like their own digital copies a large number of those held in the British National Archives collection are available for purchase on CD-ROMs here: http://www.naval-military-press.com/cd-rom-c-250.html But this is not going to be about these large-scale trench maps. For the aviators of both sides these maps, although they certainly used them in their army-cooperation, art.obs. and photo recon. roles to precisely mark the position of enemy batteries, strongpoints, supply dumps or troop concentrations, their use as a tool for navigation was strictly limited by their scale (1:10,000 being just over 6" to the mile, so a map at this scale would be overflown in a matter of minutes). You will find little indication on these maps that they were designed with aerial naviagation in mind, and there is no concession to the aviator in the colouring or the features identified on the map. For this you have to turn to some of the larger-scale maps, at a scale of 1:20,000 and above, which were printed and distributed in smaller numbers as 'special' sheets for the artillery, cavalry, tanks, aviators and General Staff. It is also of some interest to note that although 'corps' maps were produced for the various arms, 'administration' maps for the General Staff, and various 'special' maps showing road and rail networks, telephone and telegraph lines, the water suppy and potential 'inundation' areas...very few maps have survived that were made primarily for the air services, or for their use in navigation. For most of the war the airmen of both sides appear to have used whatever suitable maps that they could find for air navigation, taking whatever was available in scales ranging from 1:40,000 (approx, 1.5" to the mile), through 1:100,000 (approx. 1.5 miles to the inch), to 1:250,000 (approx. 4 miles to the inch). But as the war progressed there was some concession to this use, at least in the British maps, as over-printing a standardised map colouring and features of use to air navigation were added to some of these otherwise general purpose maps. See examples here: http://lt1.mcmaster.ca/ww1/wrz4mp.php?grid...id=304&view http://lt1.mcmaster.ca/ww1/wrz4mp.php?grid...id=322&view http://lt1.mcmaster.ca/ww1/wrz4mp.php?grid...ophoto&view http://lt1.mcmaster.ca/ww1/wrz4mp.php?grid...ophoto&view The French air service, although they experimented with the use of a small-scale map of the Chalons manouevre area before the war, remained largely dependent on a somewhat innaccurate pre-war 1:80,000 scale series black and white hachured map, and the Germans used a 1:100,000 map series based largely on the French 1:80,000 map. As the war progressed, like the British, their Field Survey units compiled larger-scale maps of the trench systems and operations areas. French 1:80,000: http://library.mcmaster.ca/maps/ww1/French1889.htm German 1:100,000: http://209.85.229.132/search?q=cache:l74aR...lient=firefox-a The first known aviation map predates the First World War by several years, although in 1910 'Flight' magazine commended the Ordnance Survey's layered half-inch (2 miles to the inch, or approximately 1:125,000) scale map as the best compromise for "motorists and aviators", as its layering of colour was useful in showing elevations at a glance to the pilot. The issue was discussed at a meeting of the British Association in 1911, but this standard OS half-inch map was criticised for being on too large a scale, a smaller scale being necessary to the pilot to keep the map sheet down to a manageable size. It was also pointed out that the map should be as free of unneccessary ground 'clutter' as possible, but with features of use to aviators identified prominently (roads, railways, towns, airfields). Following on from this meeting a map for military aviators, a coloured map at the standard quarter-inch scale (4 miles to the inch, or approx. 1:250,000) was drawn up by the Geographical Section of the General Staff (GSGS) for the British Army manoeuvres of 1911, and although the British manoeuvres were cancelled that year it was used in the subsequent manoeuvres held in 1912. Normal topographical detail was almost entirely absent, and the map was reduced to emphasising what a pilot would be able to pick out from the air - roads were depicted as white lines on an olive-green base, towns were red, woods were green, whilst water courses and railways were in heavy blue and black respectively. Landmarks such as church spires, and even individual trees, were emphasised in heavy black. The Ordnance Survey then produced its own aviation map between 1911 and 1914, on this quarter-inch scale with hillshading, red roads, red outlines to towns, heavy blue rivers and black rail lines - but otherwise identical to their standard 2nd edition quarter-inch map of the period. But there is no evidence that the Army adopted the OS map, or produced any plans to print a series to the GSGS format, although an amended version of the OS map was issued by the Admiralty in 'Air Packets' for use by the RNAS in 1916. Hillshading was omitted from this series of coastal maps, a compass rose was added, and marine lights and other seamarks were added in the form of useful little engravings of the actual lighthouse, headland, etc (Nicholson). The first RFC squadrons therefore went to war with no maps of their own, and also remained largely dependent on adapting those available from Army and other sources. The British Expeditionary Force itself was equiped with maps of the French and Belgian frontier, on a map scale suitable for a war of maoeuvre. A small-scale layered map at 1:380,000, or about 6 miles to the inch (GSGS 2517), named 'Belgium and the North East of France', was issued to the BEF and would have been available to the RFC as a map for air navigation. There was also a General Staff map at 1:100,000 (GSGS 2364) of the Belgian frontier, adapted from the Belgian 1:100,000 series - and it would have been of value to RFC pilots, as it was contoured in brown and coloured with roads depicted by red lines, water in blue and woods picked out in green. There were also quantities of the 1:40,000 scale Belgian 'tactical' maps for units in the field. For the French border areas, however, the British had to rely upon the outdated and 'miserable' black and white hachured 1:80,000 scale French 'Carte de l'Etat Major' that was issued to their own Army: http://library.mcmaster.ca/maps/ww1/French1889.htm (the French also had an excellent series of fortress 'Plan Directeurs' at a scale of 1:20,000 for the frontier areas, but these were kept secret even from their allies and were not made available to the British until October 1914, by which time they had mostly been overrun by the German Army). This was photographically enlarged to 1:40,000 scale and redrawn in colour, with contour lines added, by the British GSGS - but this had the unfortunate effect of merely amplifying the errors contained in the original: http://library.mcmaster.ca/maps/ww1/ContourOverlay.htm . The French 1:80,000 scale map series was seriously out of date by the outbreak of war in 1914 - the original survey for northern and eastern France had been done between 1818 and 1835, and although periodically revised since then it failed to adequately reflect changes such as new railways, roads, urban and industrial development. It was at a scale that was unfamiliar to the British Army, it was in black and white with elevations depicted in hachuring with only spot hights marked, and was often several hundred yards in error which made it of very limited use to the artillery. It must have been very difficult to read from the air, although it was also issued to pilots in the series GSGS 2526. With the rapid advance of the German Army into Belgium and North Eastern France, much of these pre-war GSGS maps of the frontier areas turned out to be largely useless. In the retreat from Mons thousands of them were discarded as the Army retreated back into areas that were covered by the French 1:80,000 series map only. These were in short supply, however, so small-scale motoring maps were ordered from the French firm of Taride to supplement them - and cycling maps, even Michelin guides in some cases. On 11th September a series of 1:250,000 scale maps (GSGS 2733 and 2738) arrived from the OS in Southampton to replace the dated 1:380,000 GSGS 2517, and this 'administrative' scale map series appears to have subsequently become the main map series for air navigation in WWI. Chasseaud notes a map in this scale (GSGS 2823) from August 1916, which shows the location of airfields, and there is another one on the same scale from 1917/1918 and retained in the British National Archives that has been overprinted with German airfields. This 1:250,000 (4 miles to the inch) map series had been prepared from the French 1:80,000 series, but had been redrawn in full colour with red roads, blue water, green woods, towns and the railway network marked in black - but without contours, layering or hachuring. With the British line stabilised on the Aisne, the French 1:80,000 maps were gradually replaced by fully coloured and redrawn maps at 1:100,000 and 1:40,000 based on a combination of the French map, local cadastral maps and field surveys (cadastral maps being the often very old larger-scale mapping of land ownership, showing property and field boundaries, held by local government). Although useful, these contained many errors and were therefore of limited use to artillery units firing by map coordinates, which led to the decision to start surveying the Front down to 1:20,000 scale or below for the preparation of barrage maps. It is likely that the RFC found them to be useful and were involved in their preparation, however, as they were coloured and marked in the same way as the 1:250,000 series maps and, by the end of 1915 covered the operational area from North to South "extending from the heaviest and furthest back English gun to its German 'opposite number'"" (Winterbotham) either side of the line but as far as St. Omer in the west. This series was eventually extended further west and south-west, but not until after the German Spring Offensive in 1918. It is likely that it it these maps that are referred to by the No.66 Squadron pilot Gordon Taylor, in his memoirs, when he comments that "For quick and easy reference I had pasted maps of the region for about 30 miles each side of the lines on pieces of plywood, and had made a holder for them which I had fitted beside my seat" (Taylor). With the lines stabilised, the Field Survey Companies switched their focus to the production of accurate barrage maps at 1:20,000 scale, and trench maps at 1:10,000 scale and below. These were clearly of little use to pilots, and coloured marking of roads, rivers and woods disappeared to be replaced by the use of colour over-printing to mark German trench systems and the British front-line trench. On these early maps, the British trench system was depicted in full only on the 'secret' maps held at Corps and Army HQ (and similarly, only 'secret' editions of the small-scale maps at 1:250,000 scale had the locations of British airfields marked on them). The introduction of over-printed grid-squares for referencing that became a common feature of maps at this scale is attributed to an RFC officer at the Aisne, D.S. Lewis, who squared two copies of a 1:80,000 map in pencil, giving one to the battery commander that he was spotting for. Another officer, Lt. C.C. Darley of No.3 Squadron RFC, clearly regarded the French and GSGS series maps to be inadequate - and over the winter of 1914/15 made his own map of the squadron's front by taking photographs from above the lines, developing these plates in a makeshift darkroom in the stables of his chateau billet, and fitting them together until he had enough prints to produce a map of his own. Shortly after that, in the Spring of 1915, the army cooperation units of the RFC were issued with the first purpose-built cameras and started the sytematic photo recon. of the German trench system that was to have such a huge impact on survey and map making along the whole front. One type of map that was peculiar to the RFC in this period was a series of large-scale reconnaisance plans on card. 'Railway Sidings - Card for Airmen' GSGS 3076, covering the main railway centres that lay behind the German lines. These were double-sided, and some were double-length and hinged with linen. They were clearly designed for pilots' and observers' use in the air. Maps for use by aviators made a re-appearance in a new series of 'breakthrough' maps at 1:40,000 scale prepared by the 3rd FSC for the Cavalry and the Flying Corps in the build-up to the Battle of Arras in the Spring of 1917. The map sheet GSGS 3488 'The Scarpe Valley' was sheet 51b of the regular 1:40,000 series, but with a strip added from sheet 57c to the south. There were two versions of this, the second one showing woodland and village perimeters in green, railways in red, and the roads in yellow. It omitted contours, which were regarded as unnecessary as the ground appeared to be flat from the air. After this, it became standard practice in 3rd FSC (Field Survey Compnay) to overprint the woods and the village perimeters in green on the 1:20,000 scale 'position' maps as well (the 'hostile battery position maps' with enemy batteries included as black dots). In the Messines operation 'special' sheets of this type were issued to No.53 Squadron RE8s flying contact patrols - they were to mark up the maps in the air and drop them on IX Corps 'dropping ground' at Scherpenberg. At Third Ypres two 'special' sheets were once again printed at 1:20,000 scale by 5th FSC with the woods overprinted in green for use in the air, and some large-scale plans of communications centres behind the German lines which were also probably intended for RFC use in identifying important targets for heavy artillery. At 3rd Ypres the 2nd FSC produced a special series of 1:20,000 scale maps for artillery/air cooperation, with the woods overprinted in green. At the Battle of Cambrai 3rd FSC again made 'special' maps at 1:20,000 scale with green woods and village boundaries, and also a new type of 'going' map for the cavalry and tanks at 1:40,000 scale that was clearly also intended for the RFC to use, as it included the now familiar green overprinting to the woods and village boundaries. Shortly after this a series of 'corps squadron' maps for army cooperation units were printed at 1:20,000 scale, with the now familiar green woods and village outlines, and with water courses marked in blue. These also included the zone-call over-print for use from the air, to bring down an immediate artillery barrage on targets of opportunity identified by RFC pilots or observers. Later, the hostile battery 'position' maps were produced with tree-lined roads identified by green borders. After the German Spring offensive on the Lys in April 1918, the back-area mapping was extended to the west and south west as a priority, and there was some attempt to coordinate survey and mapping with the French Service Geographique on a metric scale using the 'Lambert' projection. It appears that nothing much came of this before the Armistice, and both British and French armies regularly mapped and re-surveyed the others sector as they moved in or out. The Independent Air Force, created on 6th June, also experimented with a special 'aeronautical map' of its own, on ten sheets 19x25 inches square, at 1:250,000 scale in both a night version (GSGS 2861) and possibly a day version. These are said to be similar to the manoeuvres map of 1911, with white roads on a grey background, blue rivers and black railway lines, dark green woods, red towns and metric spot heights in white, with large expanses of water depicted in white hatched by thin blue lines. There are some examples of these sheets in the Salmon Collection in the Royal Geographical Society's map room. But it wasn't until 1919 that the GSGS took overall responsibility for service aviation mapping and produced the first sheet of a new series, the British Isles Aeronautical Series (Provisional ed.), a quarter inch (approx. 1:250,000 scale) in 1921. Bletchley Sources Chasseaud, Peter. Artillery's astrologers: a history of British survey and mapping on the Western Front, 1914-1918. Mapbooks, 1999. Nicholson, Tim. 'An introduction to the Ordnance Survey aviation maps of Britain, 1925-39' in Sheetlines, vol.23 pp.5-18, 1988. Winterbotham, H. 'Geographical work with the Army in France', in The Geographical Journal, vol.54 pp.12-28, 1919 Taylor, Gordon. Sopwith Scout 7309. Cassell, 1968.

I think XP is due to loose support around 2011, so there might be security issues after that if you have it connected to the Internet - but if it is 'stand alone' then this shouldn't be a problem. And I guess you can upgrade to Vista or Win 7 later if you need to. But as a gaming machine Vista might have even more backward-compatability problems than XP? So it depends on what other games you want to play on it, and how old they are...I wouldn't like to loose the ability, for example, to play RB3D by moving to Vista (like you, I am puzzling over this issue right now). I can't see any other advantage right now, other than more memory (which probably won't be used by OFF, but probably will be by future releases such as RoF). Bletchley

I can remember coming across a comment by one of the British aces - McCudden, I think, although I can't find the reference - that he got so close to one two-seater that, on landing, he had to wipe the blood from the Observer off his aircraft (actually, it was probably a rigger who had to do that job. But they appear to have been generally a ghoulish lot, liking nothing better than counting the number of holes in 'their' machine and pointing out to the pilot those hits that were only inches away from killing him). Bletchley

See this discussion at The Aerodrome: http://www.theaerodrome.com/forum/aircraft...g-distance.html It looks as it 2-4 nautical miles might be a reasonable distance for AI pilots to pick up an aircraft visiually. Much les than the current 8 nautical miles (if that is the current OFF standard inherited from CFS3). Bletchley

I voted OK, but I agree with Creaghorn over the AI's ability to spot enemy aircraft - if it is technically possible to reduce this in a scaleable way (as there is, inevitably, disagreement on what the WWI airman could/could not see and at what range) then this would be great :) Bletchley

If it could be done, then I like the idea as well - particularly if it could be made scaleable, so those that still wanted a lot of action could keep things as they are. Bletchley

With 'AI Gun Fire (Range)' set to "Realistic" both Anti-Aircraft Artillery and ground fire from MG guns is certainly very fierce in OFF, and especially so in the late period of the war when there is a lot more of it. My earlier suggestion was to set it to "Realistic" only for 1918, but even this is perhaps a bit too fierce (and in particular, like many others, I don't like the AI pilots' tendency to open fire accurately at what appears to be an 'unrealistic' range). Pilot attrition from both AAA and ground MGs, as a proportion of total combat losses (discounting losses from accidents and 'unknowns', which actually account for far more) was between 15% and 20% for 1917/18 for both German and British pilots (sources vary slight, but remain consistently within this range - my own figures set it at around 17% for both). Aircraft losses for the war as a whole also appear to fall within the same range, perhaps slightly more (using the figures suupplied by Henshaw at the back of 'The sky their battlefield', Allied losses were 20% in 1917, 25% in 1918). If you just look at specific months during 1917 and 1918 there are some dramatic peaks, however - 40% in November 1917 (Battle of Cambrai) and 44% in March 1918 (German Spring Offensive), with lesser peaks in December 1917 (27%, Battle of Cambrai again), August/November 1918 (29% and 28%, dropping slightly to 22%-25% in September-October). Pilot losses, however, remain consistent at 17% for both months - suggesting that the bulk of these AA shoot-downs were at low level, with pilots managing to walk away from crash landings on their own side of the lines (something supported by the anecdotal evidence). OFF appears to be rather severe on crash landings though - most of mine seem to end in pilot loss at the 'DiD' setting - so I have moved on now to flying at "realistic" just for balloon missions, and reducing the setting to "normal" for all other missions in 1916/17/18, and 'easy' for 1915 (although flying as a German pilot I would set it to 'normal' for 1917/18 and 'easy' for 1915/16, to reflect accounts of poor Allied AAA effectivness up to late in 1916). Bletchley

Don't feel bad about cancelling a mission if it looks cloudy, Siggi, I do it routinely now :) If the chaps from "Meteor" give me a bad weather warning, then I cancell immediately if it is raining/snowing at the start of a mission (just hit Esc, and take it as a mission washed-out), and if it is murky or piled up with clouds then I abandon the mission and fly it as a lone wolf mission flying well away from any cloud masses. The only change I make is if the sector is indicated as 'active' (flying in support of an offensive): in that case I will try and fly the set mission, but will turn it into a lone wolf mission if I have to follow the AI Flight Leader into or near cloud. Approximately one third of the days were regarded as 'unflyable' on the Western Front (at least in Flanders), and although in extreme cases missions were flown in bad weather these were mainly vital recon. or art obs. missions by two seaters in direct support of something critical going on at ground level, and only rarely offensive patrols by scouts. Most flying activity was in the summer months (or late spring through to early autumn), when scout pilots typically racked up the bulk of their victories. Flying in winter, even in good weather, was known to be particularly debilitating - I had a quote that I have now lost from Parks (of Battle of Britain fame) saying that pilots were good for only a few months of winter flying, after which they had to be sent back to England to 'rest' due to the physical effects. Bletchley

Hey Dej, Have you been to the Shopping Centre at Farnborough? There is a full-size SE5A replica hanging from the ceiling... Bletchley :)

Forgot one: Franks, Norman; Bailey, Frank; Duiven, Rick. Casualties of the German Air Service. Grub Street, 1999. Incomplete, but with a translation on p.8 of loss figures from 'Statistisches Jahrbuch fur das Deutsche Reich 1924-25' p.50 Table 9 listing 'The losses of the Aviation units of the German Army between 2 August 1914 and 11 November 1918' from data provided by the German Reichsarchiv. Contains a breakdown for losses, including 'shelling and ground fire' as a category. Not broken down by year or month, though. Bletchley

If anyone wants to look more deeply into this (my post really only scratched the surface), here are some of the sources I used and would recommend: Westermann, Edward B. Flak: German anti-aircraft defenses 1914-1945. University Press of Kansas, 2001. The first chapter covers WWI and early developments. A good academic look at German flak development and effectivness, although I think he probably overplayed the effectiveness a bit. Routledge, N.W. Anti-aircraft artillery, 1914-55. Brassey's, 1994 (History of the Royal Regiment of Artillery series). Another good academic text, best on British AAA. Very knowledgeable on artillery pieces, muzzle velocities etc. and sceptical about many of the figures previously published on effectiveness. Hogg, Ian V. Anti-aircraft: a history of air defene. Macdonald & Jane's, 1978. Hogg, Ian V.Anti-aircraft artillery. Crowood Press, 2002. I found both this, and the earlier volume above, to be a bit leightweight compared to Westermann and Routledge (not so much based on primary sources), but with plenty of good photographs and detail on artillery pieces. Just one chapter in each on WWI. Hide, David. 'The flying shot: the development of anti-aircraft defence', published in two parts Cross & Cockade International (vol.36, Pt.1, pp.3-22; vol.36, Pt.2, pp.71-96) 2005. This is a very good detailed examination of WWI AAA, but with little information on effectiveness. In order to get more information on effectiveness, I also examined aircraft and pilot loss figures in: Henshaw, Trevor. The sky their battlefield: air fighting and the complete list of Allied air casualties in the First World War. Grub Street, 1995 (only covers combat losses - still waiting for the promised companion volume to cover training/accident losses). Franks, Norman; Bailey, Frank; Duiven, Rick. The Jasta war chronology: a complete listing of claims and losses, August 1916-November 1918. Grub Street, 1998 (only lists scout losses, not two-seaters). Bailey, Frank W; Cony, Christophe. The French Air Service war chronology, 1914-1918. Grub Street, 2001. Jones, H.A. The war in the air: being the story of the part played by the Royal Air Force in the Great War. Clarendon Press, 1937 (Appendix volume has a month-by-month listing of British aircrew losses and hours flown, although only up to mid July 1918) Pieters, Walter M. Above Flanders Fields: a complete record of the Belgian fighter pilots and their units during the Great War, 1914-1918. Grub Street, 1998. A very complete compendium of the Belgian contribution in the air, and one that deserved to be better known. Shores, Christopher; Franks, Norman; Guest, Russell. Above the trenches: a complete record of the fighter aces and units of the British Empire air forces, 1914-1918. Grub Street, 1990 (only aces, so the loss data is a limited sample). Fedders, Peter A. 'German air losses and victories in 1917-1918' in Over the Front, vol.19 no.4, Winter 2004. A controversial article, but with a wealth of tabulated data. Sometime agao I also looked briefly at the casualty cards held in the archives at the RAF Museum, Hendon. An old article of mine on the German AA effectiveness can be found in the Reference section at the Aerodrome forum, 'Some observations on German anti-aircraft fire over the Western Front, 1914-1918' (a bit dated now), and there are several good threads on AA in the Aerodrome forum itself. Bletchley

The Wikipedia entry is not very helpful for World War I AA, as it is mostly innaccurate. The predominant AAA gun used by the German forces was the 77mm, supplemented by captured 76.2mm Russian guns (these were favoured by German AAA crews as it had a higher muzzle velocity, but once catured stocks of shells ran out they had to manufacture their own). Towards the end of the war these were supplemented by an 88mm gun, with an even higher muzzle velocity, but these were in short supply up to the end of the war. The French used a 75mm gun, with a muzzle velocity similar to that of the German 77mm. The British used a 13lb gun with the lowest muzzle velocity in 1915/16, switching to an 18lb gun that took 13lb shells (also, confusingly, referred to as a 13lb gun, but with a higher muzzle velocity than the original 13lb gun): this remained the predominant AAA gun deployed by the British on the Western Front, supplemented later by a small number of the higher muzzle velocity 3 inch gun (on a par with the German 88mm for muzzle velocity and accuracy). Both the German 88mm and British 3 inch were converted naval guns, and neither of them were as mobile as the 75/77/76.2/13lb guns which were all converted field pieces, and were therefore used primarily in fixed locations to defend strategic location in rear areas or for home defence. At the start of the war both sides had only quick firing 'pom pom' type weapons of around 20mm-37mm (1lb or 2lb for the British), firing solid shot, tracer or incendiary and designed not to shoot down aircraft but as anti-balloon weapons (it is thought that the 'flaming onions' often referred to by Allied pilots was in fact the German quick-firing 37mm firing tracer rounds). The shell of choice to begin with was shrapnel, but it was soon found to be an inneffective round against aircraft - the shrapnel rounds were shot out along the trajectory of flight when the shell burst, having little lateral spread, and even when the ball contents of a shell hit an aircraft then the spread was such that often nothing vital was hit. The Germans and French quickly switched to firing the HE round, which was far more effective as a near miss could crumple the relatively weak structure of a WWI aircraft, thus bringing it down. The British, on the other hand, had problems developing a fuse that would work reliably with the 13lb gun, and were forced to continue firing shrapnel rounds until well into 1916. These rounds burst with a characteristic white smoke from the black powder charge, and enabled Allied flyers to distinguish between those and the German HE rounds (bursting with a dirty grey or black smoke). It is possible that the smoke from British HE rounds was subsequently coloured in order to maintain this distinction, although I have seen no evidence for this, or (more likely, I think) that British AAA continued to use a small number of shrapnel rounds as 'markers'. At the start of the war both sides were essentially firing over open sights, and individually targetting or laying each individual gun in an AAA battery. As the war progressed, however, sighting, ranging, and fuse technology (along with muzzle velocity) increased in leaps and bounds so that, by the final year of the war, both sides were using very sophisticated technology (including the use of simple electrical computers) and use of centralised command centres for each battery or group of guns, with a consequent increase in overall accuracy. From early 1917 onwards the Germans introduced into flak units a new type of advanced stereoscopic binocular that used trigonometric principles to obtain the slant range distance to the target, and a new type of mechanical fuze that was more accurate at heights over 15,000 feet (over that altitude the standard powder fuzes of both sides worked less well in the thinner air at altitude, causing significant innaccuracy and a greater number of duds). All fuses in this period were timed, not activated by pressure. The British and French both introduced ranging and sighting instruments based on tachymetric methods, which measured the rate of movement required to track the target in order to calculate speed from which deflections could be arrived at: the French Brocq system converted the movements into proportional electrical currents used to calculate fuse range, and automatically computed deflections were then sent electrically to dials attached to the guns. Height finders such as the British Barr and Stroud UB2 were also employed - this used two sets of lenses and prisms at either end of a 7 foot baseline, reflecting two images that were brought together to a central point (vis Uncleal). Height was obtained from range and angle of sight, using trigonometric calculations. By the end of WWI, the AAA was probably better than that deployed at the beginning of WWII. It is difficult to find reliable figures for AAA effectiveness. The best figures are those for the German flak forces which demonstrate a significant increase in accuracy and effectiveness from 1915 through to 1918, with an expenditure of 11,500 rounds per aircraft shot down in 1915 to 5,040 rounds per aircraft shot down in 1918. The figures for French and British forces vary widely, and appear to be generally lower but it is almost impossible to make useful comparisons on the figures available as there is no indication of what the figures are based on - the best that can be said is that they are likely to follow a similar pattern. When we look at pilot and aircraft loss figures, the ratio of pilot/aircaft losses to AA fire and air-to-air combat is almost identical between British and German forces, when looked at over the whole period of the war. If we remove accident figures, the ratio between air combat and AA is 17% to AA losses and 83% air-to-air combat losses for both aircraft and pilots on both sides (so for every 100 aircraft or pilots lost, 17 of them would be lost to AA). This figure includes ground fire from MG and rifle fire. If we look just at losses to AA the figure drops to about 8% to 9%. This varied greatly from month to month, and should not be taken as a per mission frequency in OFF. Personally, having played with the settings, I now use the "Realistic" setting now only for 1918, "Normal" for 1917, and "Easy" for 1915/16. This setting also changes the distance from which AI pilots start shooting at you, so some personal compromise has to be made here. Easy, as I undestand it, means the AI has to get in close before opening fire, and Realistic means that they will fire accurately from further out. I also never except ground-attack missions, or balloon-busting missions, unless the sector that I am flying in is indicated as 'active' (i.e. I am flying in support of an offensive). I think this is historically acceptable, and helps to keep me above 3000 ft where the AA is less lethal :) Bletchley

Gwynnes, Clerget & Bentley It has long been assumed (see, for example, Mottram, but also my own posts here) that the long stroke Gwynnes Clerget 9BF engine was developed by Bentley during his time at Gwynnes - and that it was indeed a direct ancestor to the AR1 (later BR1) later developed by Bentley at Humber. But after re-examining some of the available French and English sources I now think that this is probably wrong, that the Clerget 9BF was a collaboration between Clerget et Blin and Gwynnes with very little, if any, direct involvement by Bentley (although the engineers at Gwynnes certainly seem to have incorporated much of what he had passed on to them whilst working there to improve production and reliability of the Gwynnes licence built Clerget engines - in particular, his use of aluminium alloy pistons). Bentley himself was adamant that the AR1/BR1/BR2 design had very little in common with the Clerget, with the exception of the cam. mechanism (Bentley). We know that Gwynnes was the contractor to the Admiralty for the Clerget engines used to power RNAS Nieuport and Sopwith Strutter two-seaters, having obtained a licence from Clerget et Blin & Cie just before war broke out in 1914 (Mottram; Bentley; Gwynnes; Hartmann). Before the war Gwynnes already had a long history of making marine pumps, but there was serious production and quality-control issues with the Clerget rotary engines that they were then supplying to the RNAS by early 1915. Mottram comments that "It is likely that Gwynnes were trying to apply fairly coarse marine pump quality standards to high precision aero-engines, and in cutting corners were running into serious problems" (Mottram). This led directly to poor performance and reliability from these British-built Clerget engines, when compared to those engines being obtained directly from the French manufacturers. W. O. Bentley had been recruited into the Admiralty 'E' Section responsible for supply, production and inspection of aero engines bought under contract for the RNAS. Early in 1915 he was despatched by Commander Briggs to Gwynnes at Chiswick, with the instruction "They're to do what you tell 'em to do". Bentley records in his memoirs that his main task was to "put in hand experimental work that would lead to the substitution of aluminium for iron pistons in the Clerget", but it is clear that before he could do this he first had to bring the quality of production and manufacture of Clerget engines at Gwynnes up to an acceptable standard - a task that appears to have been achieved with some difficulty, due to resistance from the Chairman, Neville Gwynne. He was to remain at Gwynnes for over a year, when not engaged in visits to front-line RNAS squadrons to assess the problems with Gwynnes built Clerget engines, and comments that "The routine at Chiswick was ceaseless and gruelling", whilst "In spite of the position of authority I occupied, I was soon neck-deep in the politics, manoeuvrings and jealousies that arise when an outsider is let into the design department" (Bentley). Although Bentley managed to diagnose and correct the immediate problems with the engines coming out of Gwynnes, he also diagnosed a more fundamental problem with the Clerget design - the 'obturator ring' common to all of the Clerget rotary engines. The rotary engine had a problem with unequal cooling of the alloy steel cylinders, which have poor thermal conductivity. The air cooling of the cylinders led to an unequal operating temperature at the leading and trailing edges of the cylinders, and eventual distortion of the cylinder into an oval shape. The obturator ring was an L-shaped ring of copper-silver alloy that was designed to conform to this distortion of the cylinder to maintain compression within it. Any wear to the obturator ring would lead to a gradual loss of compression (and therefore loss of engine power), and cracking or failure of the ring would lead directly to engine failure. Bentley comments that "It was very thin, very fragile and very unreliable; and when it broke the piston seized at once. They were given a life of around fifteen hours in France, and this was an expensive way to try to gain air supremacy over the Western Front" (Bentley). Bentley recalls that he "managed to persuade Gwynnes to raise the compression, and, because they were ordered to, they accepted the aluminium pistons", but he met "a series of carefully contrived obstructions" when he tried to "improve the obturator ring and incorporate a cylinder with good conductivity formed of aluminium with a cast-iron liner shrunk into it which would equalize the temperature". He was convinced that this would solve the problem, but he recollects that Gwynnes "thought they were being led into an entirely new design to my specifications, which would mean dropping the French Clerget rotary" and that "they were also occupied with a new rotary of their own, for which they had brought over a designer from France" (Bentley). I think this 'new rotary of their own' was probably another Clerget (I have found no evidence that Gwynnes produced any other engines at this time other than, later, the rotary BR2 and a small number of Wasp radials), and that Gwynnes had seen an opportunity to work together with Clerget et Blin to incorporate some, but not all, of Bentley's ideas into an upgraded version of the existing Clerget 9B: the long-stroke, high compression, aluminium-alloy pistoned Clerget 9BF. It is also clear that Gwynnes wanted to get rid of Bentley, as Bentley recalls that they would "rather drop me than their Clerget, and they made this so amply clear that I was forced to put my case to Briggs". Bentley left Gwynnes at this point, some time in the early summer of 1915, but was persuaded by Briggs to "return to Chiswick, work on one piston and cylinder to my specification and fit it to a Clerget to prove my case". But it is clear that Gwynnes were not thrilled to have him back, as "the results were as satisfactory to me as they were disturbing to Gwynnes", and after some "tiresome consequences" Bentley was "soon back at the Admiralty" and requesting his own removal from Chiswick "to be allowed to develop my own aero engine design elsewhere". He was then re-asigned to Humber, sometime in the summer or early autumn of 1916, who were apparently very glad to see him, having been engaged in "churning out Army bicycles - thousands and thousands of them - and terrible things like travelling kitchens" (Bentley). Back at Chiswick, it appears that Gwynnes continued to make Clerget 9B engines under contract to the Admiralty, but were now also working on the development of their new Clerget 9BF. At some point Ruston & Proctor also obtained a licence from Clerget et Blin to build the Clerget 9B rotary engine, although I can find no evidence that they were involved in development or manufacture of the 9BF. Between the two of them, these two companies produced 1300 Clerget 9B engines under licence, and Gwynnes built a further 1750 Clerget 9BF (Hartmann) - although Ruston and Proctor appear to have been contracted to make Clerget 9B engines for the Clerget Camels that they were building for the RFC from 1917 onwards, whilst Gwynnes were still contracted to supply their Clerget 9B engines to the RNAS. From March 1917 the separate supply organisations for the War Office and Admiralty were combined into a single organisation under the Ministry of Munitions, although the legacy of separate organisation continued to shape supply of aero engines to RFC and RNAS squadrons until they were themselves combined into the new RAF in April 1918 (Bentley, Meekcoms). Note on Aluminium Alloy The references often made to 'aluminium' pistons and cylinders are not quite accurate, as the metal that was actually used by Bentley is reported to have been an aluminium alloy 'L.8' that contained 12 per cent copper (Morse). Later, however, it may have been another aluminium alloy altogether, one named 'Y' alloy that was then under development by the National Physical Laboratory. The development of this alloy was itself stimulated by the pre-war development in Germany of Duralumin, and before the war had been coordinated in Britain by the Alloys Research Committee of the Institution of Mechanical Engineers. It seems likely that Bentley would have known of of this. It contained 4 per cent copper, 2 per cent Nickel and 1.5 percent magnesium, retaining its strength to moderately high temperatures and, by 1921 at least, was being used extensively "for pistons and cylinder heads" in cast form (McNeil). It was also an alloy known to Peter Hooker Ltd. of Walthamstow, which built Le Rhone engines under licence during the war (Nahum), whilst Air Board data sheets for August 1917 list a Le Rhone 9J engine with the entry 'aluminium pistons'. It is likely therefore that the otherwise rather strange 'y' designation in the Le Rhone 9Jby is an early reference to the use of this 'y' alloy. Sources Mottram, Graham. W.O. Bentley's aero-engines. W.O. Bentley Memorial Foundation (Publication no.3), 2003. Bentley, W.O. W.O.: the autobiography of W.O. Bentley. Hutchinson, 1958 Gwynnes Ltd. Clerget patent aero engines (9B & 9BF): instructions and list of parts. Gwynnes Ltd, c.1917 (facsimile reprint by Camden Miniature Steam Services, 2001). Hartmann, G. Moteurs de legende: le Clerget 130 ch. Meekcoms, K. The birth of aeronautical inspection. 198. Morse, William. Rotary engines of World War One. Nelson and Saunders Aviation Collection, 1987. McNeil, Ian. An encyclopaedia of engine technology. Taylor & Francis, 1990. Nahum, Andrew. The rotary aero engine. HMSO, 1987. Air Board. Data for structure and stability calculation of aircraft. August 1917. DSIR 36/4828 Bletchley

Or just 'E' :) Bletchley

The blip switch can be modelled with the magneto on/off commands: SHIFT +M to switch off (first time it will take 3 pokes), CTRL + M to switch back on. If you are too slow switching back on the engine will die, and you will have to restart it (historically, holding the blip switch down for too long would allow fuel to accumulate in the engine, and risk a fire as unburnt fuel caught fire as it was ejected under the cowling via the exhaust valves). If you are diving or you are coming in to land you could switch off the fuel supply instead - once switched back on (there was an on/off fuel stopcock, modelled in OFF but I forget which command it is) the windmilling of the prop would start the engine again. I have the magneto mapped to a pair of buttons on my stick. Bletchley