Hello, I am a new member and pleased to have found this discussion.
I agree with ‘bf109emil’s responses on this thread.
There seems to be little doubt the pilot(s) made a major operational error at the August 15th Neuhammer demonstration. It appears they did not establish the minimum recovery altitude and were not referring to their altimeters in their terminal dives. The surprise for this highly trained (arrogant?) squadron is, this error was contrary to operational procedures.
My family owns the Ju-87 Stuka Dive Recovery Unit (DRU, which is our own unofficial monicker for the instrument/device or alternatively called "junk/sewing machine"
) of which ‘Furyman’ posted photos.
Referring to the markings visible in the first photo: The implication of "nicht fur Horizontalflug" ought to be clear. I believe “760km/h” is the max airspeed to which the instrument is calibrated to be accurate. I believe “250” is the moment arm the unit’s mass imposes around the aircraft’s CG for weight & balance purposes.
The Stuka's DRU is an electro-mechanical device that contains an internal altimeter, a device to measure G-load, various potentiometers, rheostats, plus power & signal wiring. Input is mechanical. All signal output is electrical. The unit has a few inputs which I have not fully explored yet. But I know one is the setting for barometric pressure on the internal altimeter, and another is setting for pull-out altitude. The electrical output signal of the unit controls servosoperating the Stuka’s control surfaces to bring about or maintain the recovery from a dive within safe limits. I haven’t confirmed whether the unit was truly automatic in that it INITIATES the recovery INDEPENDENT of pilot action. Or if bomb release or a pilot’s toggling of a switch was necessary to activate the unit’s dive recovery assist functions. Perhaps the DRU could be set to be triggered by any of these 3 or more options?
The DRU’s purpose is to prevent the aircrew and aircraft from destruction caused by impact with terrain or excessive G-force. It achieved this by affecting pull-out by movement of the controls while assisting to limit the G’s placed on the airframe.
Thus, it is very likely a DRU could be operated without bomb-release. But recovery from a dive WITHOUT dropping the bombload would have different flight dynamics - and require a higher minimum recovery altitude. This would need to be anticipated by a Stuka pilot and gunner and might be the reason different sources quote different minimum operational altitudes. [Sources vary between 900m and 450m AGL]. Or these may be the difference between operational realities and a theoretical minimum.
Sources also vary in their descriptions of how DRU’s were set up and operated during a mission. However the DRU undoubtedly needs to be fed two critical pieces of information: barometric pressure allowing the internal altimeter to be accurate, and the minimum “pull-up” altitude from which the aircraft needs to recover to avoid impacting terrain. According to one source it was Luftwaffe procedure to establish the minimum altitude before a mission. One source stated the altitude information was input into the unit in flight by the rear gunner, minutes before the dive commenced. This would offer mission flexibility, so an alternate target could be selected by the pilot with the gunner verifying the ground elevation on his charts and set the new minimum altitude in the DRU accordingly.
All my assumptions and statements are open for discussion.
Best,
- Art