Out of the blue

A bonus! That’s what the sight of a reconstructed model of the World War 1 biplane, the De Haviland DH9, sitting in Bikaner’s Junagarh palace museum is. This shell of the war’s most widely produced, but problematically under-powered, bombers is said to have been put together from parts of two planes shot down in combat (but they could have been unused war surplus). The information board in front of this exhibit does not mention the reconstruction as ever having flown; nor is there any record that the aircraft bodies that were shipped here came with engines or armament. These disabled planes were what was called the Imperial Gift of 1920, in return for the 500 Bikaneri troops who served Britain on the western front in the World War 1.

Even so, it was an instructive display. The planes of that era had very little thrust. The DH9 engine developed only 170 kW of power. As a result, stable flight required a relatively large wing surface. The wingspan was almost 13 meters, giving a total wing area of for an empty weight of just over 1000 Kgs. Half a century later, the popular Cessna 210 had a wing surface which was about two and a half times smaller for almost the same weight, flying on an engine which gave 230 kW of power. Unlike the model on display, the real DH9 had wings covered in fabric, and the rigging required a special wire with an aerodynamic profile.

It is interesting that the Imperial War Museum and the Historic Aircraft Collection in UK own two working models of the DH9 which have links to this war gift. The full story is told at the website of the HAC by Guy Black, the person who did the restoration. In brief, the remnants of the aircrafts were found in a dump yard behind Junagarh, and several rarer parts of the aircraft could be salvaged for use in the two models. I learnt that flight-worthy reconstructions of historical planes have tremendous amount of replacements due to flight safety concerns. So the amount of salvageable material from the Bikaneri relics is considered substantial. I am well aware of the problem that museums of computers and information technology face in sourcing important historical equipment, since we all treat old equipment as disposable. It was fascinating to see this same story play out in another domain of engineering.