Discussion in 'Air War in Western Europe 1939 - 1945' started by Martin Bull, Mar 18, 2003.
Avro Lancaster Mk.I LM.257 HA-P
Comments on the bomb sights, Martin? I have a feeling you had the best??
Bomber Harris and his aircrews were not slow in voicing their strong dislike of both the Mk lX and the ABS. and called for their early replacement. Their strong views were registered with the Tizard Committee and a founder member of that committee Prof. Blackett volunteered to design a new sight to meet the needs of Bomber Command. He was given facilities at Farnborough and the services of a small team of engineers. The bombsight that resulted was the Mk XlV regarded then as the wonder sight of the day. It was designed to enable the run up to the target flying straight and level to be restricted to a mere ten seconds and enable the pilot to carry out evasive manoeuvres on his approach to the target. It could be used to bomb both on the climb and the glide. The bombsight consisted of a computer cabinet mounted to the left of the Air Bomber and a stabilised sighting head with optical graticule. The sight was one of the first practical uses for a mechanical computer and Babbage would have been proud of it.
This was the bombsight of choice for Bomber Command until the end of the war and beyond. Shortly after its entry into service, its manufacture was subcontracted to the Sperry Gyroscope Company in America who after re-engineering it to meet American standards, arranged for A.C. Spark Plug , Division of General Motors to manufacture in quantity. Known as the ‘T1’ version a total of 23,000 were made for use in the RAF and Commonwealth. airforces. In some respects, it was a mechanical improvement on the British manufactured sight but was fully compatible with it in every way.
The principal source of inaccuracy was the need to set on the computer the wind speed and direction which under operational conditions, could be often in error.
A T1A version was produced for use with the faster Mosquito and to allow for the greater operating height.
For a time the USAAF considered using the T1 on their medium sized bombers but declared it to have a fault and rejected it. The reason remains unknown it was probably unsuitable for the tactics used and the Norden was predominately used.
The ABS continued its development at Farnborough and emerged in August 1943 as the SABS Mk llA tachometric precision bombsight precision sight. The SABS provided an even more complex mechanical computer being able to calculate its own ‘wind’ and to automatically release bombs. These were qualities it shared with the Norden and probably the German Lotfe sight.
Starting in 1941 Barnes Wallis had designed a range of very large bombs,namely the ‘Tallboy’ of 12,000lbs‘ and ‘Grand Slam’ of 22,000lbs. These bombs to be effective, had to be dropped within 150 yards of the target from 20,000feet and the SABS MkllA proved to be the ideal sight for this purpose. A direct hit was not required as it was anticipated that the bomb if landed just short of the target would travel forward under the target before detonating. The resulting explosion would destroy the foundations of the target causing a degree of damage that would take many months to repair.
This sight was mainly fitted to the Lancasters of 617 squadron and used in their precision bombing of tunnels, V1 and V2 ;launch sites. In company with 9 squadron using ‘Tall boy’ and ‘Grand Slam’ earthquake bombs the German battleship ‘Tirpitz was sunk in 9 minutes of commencement of attack. To achieve such a high level of accuracy required a considerable amount of bombing practice on the bombing range. These attacks were carried out by day or by night.
The accuracy of 617 squadron improved greatly with an average radial error of 170 yards being recorded over the period of June to August 1944 and improved to 125 yards in the period of February 1945 to March 1945. Two other precision bombing squadrons were formed based upon the MkXlV bombsight and in the period of February to March 1945 their average error was 195 yards. It is not surprising that when the Norden was offered to the RAF later in the war it was rejected.
Less than 1,000 SABS bombsights were manufactured and after the war great difficulty was experienced in finding sufficient sights to equip two Lincoln squadrons for precision bombing against Japan. Compare this with the 23,000 T1 sights manufactured in America.
There was in Bomber Command at the time much discussion on the comparative merits of the two bombsights. The SABS although potentially more accurate lacked the degree of tactical freedom afforded by the MkXlV/T1. As a result the MkXlV/T1 was known to Bomber Command as the ‘area’ bombsight of the RAF and the SABS as the ‘precision sight.’
It was a much more complex sight to use and to maintain than the MkXlV/T1 and required more man-hours in manufacture. For the majority of the squadrons in Bomber Command the MkXlV/T1 was still the preferred sight.
A more controversial aspect was how the American, British and German sights compared. The Norden, the SABS and the German Lotfe 7D or H were all tachometric sights used in the sitting position Norden and Lotfe 7D/H both had direct connections into the automatic pilot systems. so that in the run up to the target the bomb-aimer effectively flew the aircraft without the intervention of the pilot. Work on a SABS Mk lll was cancelled in 1943 which may have had this facility.
The SABS Mk llA uses a simpler system in that was connected to an instrument called the Bombing Direction Indicator(BDI) which was mounted on the pilot’s instrument panel. The BDI indicated to the pilot the amount of turn required left or right to bring the sight on to the target..
Using the Norden bombsight, USAAF bombardiers rarely matched the accuracy of those of 617 squadron, or even those of 9 Squadron when using their MkXlV. It could have been the greater proportion of time spent by 617 squadron practicing over the bombing ranges, and a higher standard of Air bomber..
Using tactics devised from pre-war experiments it was standard USAAF practice to fly over hostile territory in large tight formations relying upon the massed machine guns of the formation for defense. Only the bombing leader or his deputy would use their Norden bombsights with the remainder of the formation, dropping their bombs upon sight of the leader’s weapons leaving the aircraft..
It was therefore not surprising that only 31% of American bombs would fall within a radius of 1000ft of the target. Further factors were thought to be due to inaccurate settings on their bombsights and higher than specified manufacturing tolerances.
RAF Aircrew veterans will recall the claims of the time that an American Bombardier using the Norden could drop a bomb into a ‘pickle barrel from six miles up’. This was a myth but is still attached in some measure today, to the Norden bombsight; although oddly enough, not to the equivalent Sperry sight..
Fortunately the Luftwaffe lacked an effective bomber force to demonstrate the effectiveness of their Lotfe sight. Our German friends may be gratified to know that at one time earlier in the war the German Lotfe 7D sight was found to be so good, the suggestion was made to equip a RAF squadron with sights gathered from crashed aircraft. RAE Farnborough strongly objected to the suggestion and nothing more was heard of the proposal.
In contrast to the Americans many RAF aircrew and the British public remain unaware of the existence of the SABS bombsight. No articles dedicated to the sight appeared to have been published and it is rarely mentioned in books.
The Mk II Stabilizing Automatic Bomb Sight ( or SABS ), despite being a very primitive computer by todays' standards, could, in the hands of a skilled crew, produce an average error of less than 100 yards from a height of 20,000 ft.
One big snag ; conditions had to be very clear allowing a clear view of the target. The bomb was released two miles from the target and the aircraft had to fly an even, precise course for a considerable length of time prior to release to enable the various air temperature, wind, drift, speed, humidity etc factors to be calculated and input to the SABS.
So, in short, clouds, predicted flak or the Luftwaffe could really ruin the RAF's day !
These limitations resulted in 617 Squadron being the only one to use this highly specialised weapon for selected targets.
The only other viable alternative for really accurate bombing was to go in very low indeed ( Dams Raid, Ploesti, Gnome-Rhone, etc ).
The trade-off was always accuracy against unsustainable losses.
I'm posting this especially for Ta152...
did you see that Nicholas painted a Ju 88G-6 coming up from below and astern, it's placement so well concealed in the land mass.......
anyway, Ta and Martin does the upper fuselage turret look to high and too big in your opinion(s) ? Also was this a 4 or two barrel .303 installation ?
Treading carefully - as the Halifax is not my strong point - I think the aircraft depicted is a B MkII Series 1.
This featured the rather obtrusive and bulky Boulton Paul C Mk II mid-upper turret which gave this Mark of Halifax a distinctive 'look' ( although I think Nicholas T may have exagerrated this just a little ).
This was a two-gun .303 turret.
OK funny person, after looking for a JU-88 for 20 mins. and getting a headache, I figured out there is no Ju-88 ! I hope there is a skud attack in your area soon !
I think the picture is a B Mk II series I Halifax but the way they numbered the Halifax I could be wrong. It did have a huge top turret with 2 x 303 and a tail turret with 4 x 303.
H. Page did not want any turrets on the plane except for a tail turret but in 1941 they still had the notion that bombers could operate in day light and Air Marshal Freeman wanted the plane to have turrets.
Thanks for finding the picture,if you need to find me a Christmas present this year, look no further !
A skud attack........holy S***, no thnaks, not here in my neck of the woods of survivalists ! The thing would probably land in one of our cesspool lagoons.
sorry for the confusion as I was only joking....
OK Martin/Ta, another odd ball question from the inexperienced ......
The painting depcits a Hali Pathfinder correct ? When were the Pathfinders in operation with the below radom exquipped in the fuselage ? Lancs only and what was this device. Need to be educated as I have a big 0 on RAF radar Equipment.
From the wierd way you wrote that last post, I think you are smashed over the birth of you Grandaughter !
I will check on the pathfinder mission tonight.
Perhaps skud missles are too inaccurate, how about a nice US Navy launched Tomahawk missle ? They seem to be landing all over the place.
The painting is of a 35 squadron Halifax and a nice site on 35 squadron is at http://mysite.freeserve.com/archie_bombercommand/35squadron.html
It has some operations information and a nice group photograph. They also flew B-29s and the beautiful Vulcan.
I just found a photograph of Halifax TL P and yes the painting of the plane has the base of the mid upper turret just alittle too big. In the photo it sat down in the fuselage more than in the painting. If I knew how to post pictures I would post it.
Charlie don't Surf is on the board, send him a private as he has done so. My understanding is that you have to do it from a link on a web-site ? doesn't make sense to me but maybe that is how you do it.....
Is this what you want me to do or is it another picture?
Best regards/ Daniel
Erich, the radome is H2S but I'm really tired just now...have to wait for the morning to get more info...ZZZzzzz
Impressive shot Daniel !
Martin, as you look things up tomorrow, was the H2S radome retractable ?
Man, there is still so much elctronic gizmo's from both sides of the conflict that have not been covered in detail....
Firstly, the 'dome' wasn't retractable, it was just a perspex 'blister' beneath the fuselage.
H2S was a ground-tracking radar which could be used as a navigational aid and as a blind-bombing device. Unfortunately, mechanical failure was frequent, reception of the reflected impulses was difficult and interpretation of exactly what the navigator saw in his screen was very 'hit and miss'. Water features showed up best which was what made, for instance, Hamburg just about the 'best' H2S target and Berlin the worst.
Funnily enough, H2S was first fitted to a Halifax ( V9977 ) for trial in March 1942 ; this aircraft crashed in Wales three months later killing all on board, including some valuable scientists.
H2S was first used operationally by Pathfinder Stirlings ( 7 Sqn ) and Halifaxes ( 35 Sqn ) on 30/31 January 1943. On the very next raid, February 2nd, an H2S-equipped Stirling was shot down near Rotterdam giving the secret away to the Germans, who produced countermeasures ( including NAXOS ) which could home onto the H2S impulses.
The book to have on this subject ( and I haven't yet found a copy ) is 'Instruments Of Darkness' by Alfred Price.
Now, here's an 'academic' website which explains H2S quite well, BUT - and I really hesitated before linking this site in - you'll see a photo of a Lancaster proudly captioned as 'A Halifax Bomber '. Doh!!
Anyhow, ignore the photo and read ; -
Unusual picture of a Stirling in German markings. http://homepages.tesco.net/~stirling.project/n3705.htm
This site is trying to restore a Stirling nose section.
And two really nice colour photos of Stirlings can be seen at : -
more PC problems again /! printing words out of cyber space on some of the other threads.....very strange.
instuments of Darkness by price is a keeper if you can find a copy. i am still looking for a copy even if it used. wrote Price a year ago and no response. didn;t seem eager to communicate.
Naxos was developed to counter the H2S threat and was created into a series of odd ball looking boxes and domes for the German night fighters. Naxos ZC was probably the most widely used and was very much dependent by the bordfünkers to aim their Bf 110G's and Ju 88G-6's towards the RAF bomber pulks when the Fug 220d sets were starting to be countered. I think somewhere in the vent of 6 Naxos types were fitted. the last to be developed for the futureistic Me 262B-2a a/c. Out of the German nf crews I have interviewed, the Flensburg was done away with in early 45 and the Naxos seemed standard and kept till war's end.
Great pic links guys !
E c'mon pc hang in there.......it's ready for the a/c junk pile soon...