Antique aviators altimeter with 5” silvered, engraved brass, dual concentric dial: the upper portion of the centre marked “Compensirt,” with Lufft logo, as dividers astride “GL” in an oval cartouche, signed by the maker “G. Lufft, Stuttgart;” the lower with the legend “Höhenmesser für Flugzeuge,” (Altimeter for Aircraft) “No 1743,” the outer rotating dial actuated from the bezel, marked “Meter” and calibrated from 0 to 3,000 metres, with 10 metre divisions and stations incrementally at 500 metres, dual-marked for day and low light observation, the larger numbers luminised, each 100 metre station with corresponding luminised marker. Blued-steel pointer set beneath a heavy deep bevelled ¼” gauge glass. High quality conventional single 2½” capsule-driven movement, with temperature compensation, constructed in lacquered brass upon a steel chassis, blued-steel set screws. All contained within a spun aluminium case having articulating side-mounted suspension rings set at 12, 4 and 8 o’clock. The case rear with compensation port at 4 o’clock.
A very rare and most interesting early production instrument, with aspects of the design of the case derived from the earlier Negretti & Zambra aviators altimeter listed elsewhere on this site. It will be appreciated that the maximum indicated altitude rose markedly in the pre-WWI years, and rapidly through the war. We have observed three other similar instruments: serial no. 1965 scaled to 5,000 metres; no. 7687 scaled to 6,000 metres; and no. 20794 scaled to 8,000 metres. This instrument, no. 1743, is the earliest with a maximum indicated altitude of 3,000 metres. It is known that Lufft added aviation altimeters to its catalogue just a very few years before the outbreak of WWI, before switching to the production of aviation altimeters only during the war.
These early aviation instruments were not designed for mounting within a control panel but were suspended on springs picked up on the rings on the case and affixed to the structure of the aircraft. This minimised vibration and shock to the delicate movement during operation. With reference to the photographs below, the case and bezel are serially numbered together “13,” the rear of the movement chassis is stamped with the Lufft logo. It will be noted that, unlike the early Negretti & Zambra aviation altimeter, this instrument lacks any means of locking the field height and preventing accidental change in the value originally set.
The image of the inner dial showing the peripheral area usually covered by the outer dial is important. Here, the calibration sector showing a range of 720-800 millibars can be seen. The zero marker, set at 760 millibars, is visible with the instrument fully assembled. During manufacture, the altimeter would be set to read 760 millibars and tested in a chamber for that reading. The pressure in the chamber would then have been altered to the next known value, either 750 or 770 millibars and checked for error, this process repeated over the range shown.
This aviators altimeter is fully operational, and has both good sensitivity and progression. The bezel rotates smoothly through 360 degrees in both directions. The aluminium case with small dent to bottom rear edge, the instrument remains original in all respects.
A very desirable collector’s piece from this earliest period in aviation history.
Dimensions: 5½” diameter excluding suspension rings x 2¼” deep
Stock No: BA0324
FOR MORE INFORMATION ABOUT THIS ITEM, PLEASE CALL +44 (0)1584 841210 OR COMPLETE AND RETURN THE FORM BELOW