British Bomb Sights

[Greyman]

A small book could be written on the subject, but yeah, basically there were special 'wind-finding' aircraft in the raid that got the information out to the crews.

 

[Koopernic]

A small book could be written on the subject, but yeah, basically there were special 'wind-finding' aircraft in the raid that got the information out to the crews.

Berlin: The Sixteenth Raid by Bomber Command III
Undoubtedly the major factor in the night's saga had been the wind. On the 25th March, the Meteorological Section of Bomber Command HQ was visited by the Director of the Met Office of the Air Ministry, Doctor Petterssen, to discuss the difficulties in forecasting winds from available data over enemy territory. It was agreed, particularly in the light of winds forecast, and the actual winds found on the night of the 24th/25th, that more upper air data from Sweden would be of assistance on these occasions. An analysis of navigation for this Berlin raid was undertaken to discover reasons for the wide scatter of the force and its displacements to the south of the ordered track. The southerly displacement obviously resulted from a systematic error in the broadcast winds, both past and forecast, the strength being in all cases too low. This under-estimate of the strength was due in about equal proportions to:

1. Lack of belief in the unusual wind strength on the part of the many wind finders.
2. The time delay between the transmissions, by wind finders,and their reception at Bomber Command HQ.

The wind finders transmitted less than half the winds that they found, 40% used the recommended period from 15 to 30 minutes for wind determination. The main reason for the scatter was that only about 55% of the winds used by navigators was the correct broadcast winds. Very simply this meant that the wind finders just could not believe the winds speeds they were reading and reduced them by anything from 5 to 15 mph. In turn, the Met boys in England could not believe even these reduced figures. So winds of 115 mph were reduced to around 110 by the wind finders and down to around 95 mph by the Met people at Bomber Command. The estimated true winds coming from the north and the use of the slower wind estimations when calculated to courses to fly, caused the aircraft to drift more and more to the south off track and into the flak defences of towns they should have not flown near – hence the heavy losses. It really was a case of a war with the elements – and the elements won.

 

[fastmongrel]

Interesting to note, that even in the post war period, with access to the Norden and the SABS, the RAF decided to stick with the Mk.XIV on the V Bomber program

The optical bomb sight was only a back, up the main bomb sight was the Navigation and Bombing System an automatic analogue computer blind bombing auto pilot that used data from a variety of sources H2s radars, Green Satin Doppler Radar, Radar altimeter, true airspeed unit, air temperature and weather data from recce aircraft. The crew would never see the target and usually flew with all windows covered by anti flash blinds.

 

[Koopernic]

The StuVi 5B with BZA computer attachment was a dive/slide bombing sight used by the Luftwaffe. It continuously computed the impact point and present the cross hair to the pilot. In a way it was like the MK.14 in that regard. The two sight crossed over in function in the forward facing Mk.16 version used on the Mosquito for attacking shipping and U-boats at low level. The BZA working through a periscopic sight replacing the StuVi 5B was used on the Arado Ar 234. (StuVi could be used without the BZA and was so on the Ju 87)

Aircraft such as the Ju 88 could carry both the Stuvi 5B and the Lotfe 7 level bombing computing sight. To get a good dive bombing result the Lotfe 7 was used in the run up to target to ensure not only that the wind was estimated accurately but that the run up to the target and commencement of the dive was precise and optimal before switching to the StuVi 5B.