Dreieckrechner DR 3 Tp

This is a navigator’s wind-triangle calculator (Dreieckrechner), dated March 1944. A navigator lined up the aircraft’s course, airspeed and the reported wind on rotating discs. He then read off the drift angle and the heading needed to stay on track, without pencil or chart. When flying at night over a blacked-out Reich, often in cloud, this was how a crew found its way to the target and home again.

The construction is layered. There is an outer compass ring with cardinal points and a degree scale, then a rotating yellow disc carrying a black and red course scale. On top is a grid of drift lines from +16 to −16, with rings for wind strength as a percentage of airspeed, from 5% to 30%. A clear cursor with a red hairline and a blue heading arrow turns on a polished aluminium hub.

The data ring is fully marked: Dreieckrechner, Baumuster: DR 3 Tp, Anforderz. Fl. 23825, Geräte-Nr. 127-107 D-1, Fertigstellung: März 1944 and the maker code gwr. It is a complete set of markings, clearly legible, with the production month.

The printing is crisp and the colours are still strong. The clear plastic has toned to a soft ivory with age, as these instruments do. All discs turn. A real instrument from the last full year of the air war, where the yellow of the disc still reads as it did in the cockpit light.

Details:

Type: Dreieckrechner, Baumuster DR 3 Tp
Requisition no.: Fl. 23825
Equipment no.: 127-107 D-1
Completed: März 1944
Maker code: gwr
Condition: very good, age toning to the clear plastic, all scales legible, discs rotate