German Bomber Designs & Questions

[Zipper730]

Have a look at this earlier post of mine because it has some nice photos of the StuVi 5 installed in both Ju 87. Note the 'angles' drawn on the side of the Ju 87 which was not just on Ju 87 but all Luftwaffe fighter bombers for determining the dive angle. They did have an artificial horizon but the line was more practical.

While this might sound repetitive: Artificial horizons used a gyro, correct?

The Other illustration is of the complexity of the installation of both a Lotfe 7 and a Stuvi5/BZA simultaneously into a Ju 88A4. The Stuvi 5/BZA combo is by far the most complex computationally.

I never would have that. That said, I'm surprised the Lotfe 7B is so small in appearance -- it seems small compared to the Norden.

I never knew that the SABS Mk.I wasn't gyro-stabilized either.

The Stuvi 5 with the BZA and the Mk XIV both used gyroscopes but they would work by changing the position of the cross hairs to tell the pilot or bombardier as to where the bombs would go so that the aircraft could be reposition. This allowed the bomber to be manoeuvred during the attack.

I'm curious what the gyro limits were for bank/dive.

The Mk. XV allowed the altitude input to be taken directly from a radar altimeter, eliminating these inaccuracies and any instrument lag. The Mk. XVII was a Mk. XV modified for the very high attack speeds of the Naval Mosquito at more than 400 mph (640 km/h). As the Naval Mosquito did not have a bomb aimer's position, an unstabilized version of the sight head was mounted in front of the pilot.

I remember a system used on a variant of the Me 262 like this. I don't know if it ever entered service, of course.

Post war the RAF used the Mk XIV for decades in the V bomber force because now they had cross and headwind information from the inertial navigation system and doppler radar. It was now a completely automatic sight.

I'm impressed that they were able to keep a bombsight updated from the 1940's to the 1960's and still make it work well.

 

[Koopernic]

Artificial horizons used gyroscopes to keep level and compasses to provide a compass heading as well. Devices without gyros would fail in negative g or turn flight. The gyros still needed a pendulum or tilt instrument to find level.

Most of the bomb sights had their own gyros but there is nothing to stop the bombsight using a central reference as was practice on ships and I think this is what the BZA did.

The Norden had the optical sighting head and computing unit separate. The Lofte integrated it into one compact unit which also simplified calibration and alignment.

The RAF settled on the SABS.II (which did have gyros) just as the Germans settled on the 7B/C version which did have gyros.

The essence of sights such as SABS.II, Lofte 7C, Norden etc was that they could determine the drift of the bomber from head winds or cross winds. As soon as inertial navigation and doppler navigation radar was available this feature was no longer needed.

Mechanical computation was in general far more accurate than electronic, at least until the 1960s or so. The Instruments that converted a mechanical position to electrical were a source of error even in digital system. By staying in the mechanical realm this was avoided. Plus its immune to EMP. The ATLAS ICBM used mechanical inertial navigation and the USN considered converting Iowa and Missouri to a digital fire control system but they concluded there would be no improvement. It would be cheaper and more compact if doing it from scratch but that wasn't the issue.

Inventing Accuracy by Donald McKenzie covers the development of inertial naviagation.

 

[Zipper730]

Mechanical computation was in general far more accurate than electronic, at least until the 1960s or so. The Instruments that converted a mechanical position to electrical were a source of error even in digital system. By staying in the mechanical realm this was avoided. Plus its immune to EMP. The ATLAS ICBM used mechanical inertial navigation and the USN considered converting Iowa and Missouri to a digital fire control system but they concluded there would be no improvement. It would be cheaper and more compact if doing it from scratch but that wasn't the issue.

Inventing Accuracy by Donald McKenzie covers the development of inertial naviagation.

I didn't know mechanical computation had such reliability. The immunity to EMP makes sense though.