An overview of the Hindenburg’s flight instruments and flight controls.[To learn how the ship was flown, visit the Flight Operations page.]
The Control Car
Hindenburg was navigated and conned from the ship’s control car (“Fuhrergondel”), which was located toward the bow of the airship, at Ring 203.
The control car was divided into three sections; a control room or “bridge” at the front, a navigation room at the center, and a observation room or lounge used for relaxation and conferences.
(The rear portion of the gondola is sometimes incorrectly referred to as a radio room, but the ship’s radio room was actually located just above the gondola, inside the hull, along the keel.)
Flight Instruments and Flight Controls
- Flight controls
- Engine telegraph
- Rudder wheel
- Elevator wheel
- Elevator panel
- Automatic pilot
- Ballast control
- Hydrogen control (gas board)
- Echolot (sonar altimeter)
- Navigation instruments
The Hindenburg’s principal flight controls were the rudder and elevator wheels for controlling heading and pitch, the gas board for valving hydrogen, and the ballast board for releasing water ballast. An engine telegraph transmitted orders to mechanics stationed in each of the four engine cars.
Orders regarding engine speed and direction were transmitted to the engineering room along the keel and to the four power cars from an engine telegraph located at the starboard side of the control car; the telegraph had toggles to alert mechanics in each of the four engine cars and the engineer’s room of changes in power settings, and could transmit orders for four forward speeds (idle, slow, half, and cruise), two reverse speeds (idle and full), and stop.
Adjacent to the engine telegraph was a tachometer, an altimeter, and a variometer (or vertical speed indicator).
There was also a speaking tube to communicate with riggers along the axial catwalk. (Communication throughout the ship was normally by telephone, but to avoid the risk of sparks, no electrical equipment was placed along the axial catwalk.)
Hindenburg’s heading was controlled by the ship’s rudders. The helmsman, or rudderman, stood at the front of the control room, facing forward, and steered by reference to a gyro compass repeater in front of the wheel. (The repeater, or “daughter compass” as it was called by the Germans, was controlled by the master gyroscopic compass located on the ship’s electrical room.) The rudderman also had a magnetic compass and pointers indicating the angles of the upper and lower rudders.
The rudder wheel was considered an easier position to master than the elevator wheel, and airshipmen began their training on the helm, and only advanced to the elevators after gaining sufficient experience on the rudders.
Hindenburg’s pitch was controlled by the ship’s elevators. Operating the elevators was much more challenging than operating the rudders, and the position was assigned only to the more experienced crew members.
The elevatorman stood “sideways,” facing port, with the elevator wheel and control panel in front of him. While he could watch the horizon from the side windows of the control car, the elevatorman was expected to control the elevators primarily by reference to the instruments on the panel in front of him, combined with a feel of the ship that could only be acquired through experience.
The elevator panel contained various instruments to keep the elevatorman constantly aware of the position of the elevators, the pitch of the ship, and the factors which could influence pitch and altitude. The panel’s equipment included:
- Pointers, indicating the angle of deflection of the port and starboard elevators, and both elevators together (graduated up to 20 degrees deflection)
- Two inclinometers (curved tubes similar to a carpenter’s spirit level), one with a rough scale showing plus or minus 20 degrees of pitch, and the other with a fine scale showing plus or minus 5 degrees of pitch
- Thermometers, indicating ambient air temperature and the temperature in gas cells 5 and 13
- Thermohygrometer, indicating air temperature, relative humidity, and absolute humidity
- Statoscope, indicating changes in barometric pressure (and thus altitude)
- Variometer (or vertical speed indicator) indicating the ship’s rate of climb or descent
- Stop watch
An automatic pilot made by the Anschutz Company of Kiel utilized servo motors to control the rudder and elevators. The auto-pilot was used only in calm conditions, and if rough or bumpy weather were encountered, the system was disengaged and the elevators and rudders were shifted back to hand control.
The ballast board, located just to the right of the elevator panel, allowed officers to reduce the static weight of the ship by using toggles to release water ballast.
The ballast board indicated how much water was present in each of the ship’s seven main 2,000 kg (4,400 lbs) ballast tanks, and had red and green indicators for the eight 500 kg (1,100 lbs) emergency ballast bags (four located at Ring 47 toward the tail, and four located at Ring 218 toward the bow). The ballast board also had weigh off indicators for the bow or stern, indicating up to 2000 kg (4,400 lbs) heavy or light.
The gas board controlled the ship’s lifting gas, and allowed officers to release hydrogen to increase the static weight of the ship.
Toggles controlled the ship’s 14 maneuvering valves, and could be used to release gas from individual cells. (Hindenburg had 16 gas cells, but the two cells at the stern of the ship, Cells 1 and 2, were interconnected and shared one maneuvering valve, as did the two cells at the bow, Cells 15 and 16.) A large wheel could also be turned, valving 11 of the large cells simultaneously (Cells 3-11, 13, and 14).
To indicate the inflation of the gas cells, the board had a diagram of the ship’s cells, each containing a red light which was illuminated when the cell (or pair of cells) was at 100% fullness. Beneath the diagram were indicators showing the pressure within each cell.
Hindenburg was equiped with a sonic altimeter known as an Echolot (sometimes referred to as an echolade by U.S. Navy observers) which used the principle of active sonar to measure the ship’s height above the ground. The Echolot consisted of a compressed air siren located near the bow, which gave off a whistling sound that bounced off the ground and was picked up by a receiver located behind the control car; the time it took for the signal to hit the ground and return was measured and indicated the distance above the ground.
The Echolot had a clock-style indicator with a pointer to indicate the ship’s actual height over the ground, up to 500 meters. It was observed to operate with high a high level of accuracy at various altitudes and airspeeds.
The Echolot was used at least once per watch to calibrate the ship’s aneroid altimeters, which became inaccurate as the ship passed through areas of varying barometric pressure. The Echolot system itself was calibrated when the ship was over an object of known height, such as the hangar at Frankfurt.
Hindenburg was navigated from the navigation room, which contained work tables for the officers, cases for charts and maps, and navigation equipment including gyro compass repeaters, an optical drift indicator, radio direction finding equipment, an altimeter, and a clock and stop watches.
Hindenburg was primarily navigated by dead reckoning during trans-oceanic passenger flights, and the officers’ ability to accurately measure the ship’s angle of drift was the key to their precise navigation.
Hindenburg’s primary drift indicator was a Carl Zeiss instrument located in the Navigation room (visible in this photo, below Ernst Lehmann’s shoulder), which featured a large telescope extending through the floor of the control car. The telescope provided a view of the surface below and the lens had a series of black parallel lines etched upon it; at the appropriate level of magnification for the ship’s altitude, ripples on the ocean or objects on land would pass through the field of view so rapidly as to appear as a series of parallel streaks, which were aligned with the etched lines to indicate the ship’s angle of drift. The eyepiece was located slightly above the navigator’s desk, and the telescope could be adjusted for magnification between four and twenty power. A gyro compass repeater (or “daughter compass”), controlled by the ship’s master compass, was placed next to the optical drift meter, allowing drift measurements to be taken with one eye on the compass so that accurate course headings could be determined and relayed to the helmsman.
Hindenburg had another optical drift indicator in the control room (visible to the right of this photo), but it was not considered satisfactory by the ship’s officers and the Zeiss drift indicator in the navigation room was much preferred.
At night, the ship’s 5.7 million candlepower Hefner searchlight, located in the electrical room aft of the control car, illuminated the surface and made drift measurements as simple and as accurate as observations made during the day.
When visibility conditions prevented continuous observation of the ground, and allowed only momentary sightings of the land or water, less accurate but still usable drift measurements could be taken taken with a simple device consisting of several wires mounted in a V-shape through which glimpses of the surface could be observed.
The navigation room also contained radio direction-finding equipment, which used loop antennas (seen in the photo the top of this page) to could take bearings on radio stations on land or aboard ships at sea.
In addition to equipment relating strictly to navigation, the navigation room also housed a 14-station telephone with connections to various stations around the ship; controls and indicators for the control car landing wheel and spider lines; and a pneumatic tube to convey messages between the control car and the radio room along the keel.