We wrap up the week with a fun little printable prop- a blueprint for the Dornier Wal Do-J flying boat used by the Miskatonic University Antarctic Expedition in Lovecraft's "At the Mountains of Madness". You can click through on the picture below for a higher resolution graphic, or download an 11 X 14 PDF over here.
In the upper left you'll find the rundown of the plane's electrical system. That information is based on the stock Wal's 24 volt configuration, modified by the addition of two heavy duty batteries and a backup two-stroke gasoline generator. In flight the craft can function perfectly well with the current from the airstream generator on the top deck. The secondary generator is used primarily to power the engine warming gear when the plane is on the ground.
The engine specs in the middle left are based on the ones used by Wolfgang von Gronau on his around the world flight. This is the one place where I engage in a bit of handwaving. Although the engines are close to stock I've assumed that the Miskatonic expedition used aviation gas with an octane rating of 93 or above. Fuel of that quality was available within the time frame of the story and would be commonplace by World War II, powering the high compression engines of cutting edge fighters.
There are a few modifications to the stock airframe that aren't noticeable on casual examination. I've shortened the body and assumed that some of the steel frame has been replaced by machined aluminum, cutting the weight of the plane. Extending the lifting surface of the main wing helped generate more lift and significantly dropped the overall wing loading.
I combined some details of the radio sets carried by the first Byrd Antarctic expedition of 1928-1930 with the ones used by Charles Lindbergh and his wife during their Pacific survey flight in 1932. Although the Lindbergh flight occurred later in the timeline it's equipment (the Pan-American 10C) was first available in 1929. The 50 watt telegraphic transmitter on board the Miskatonic Wals would have given them a communications range of over 2000 km, while the emergency transceiver would have been limited to around 650 km.
Finally, the blueprint mentions the "fuel-warming and quick-starting devices worked out by Pabodie". This material was based on the modifications made to aircraft used by both arctic and antarctic expeditions throughout the twenties. It includes a rubberized canvas shroud for insulating the engine pod during warmup, electrical heating elements for the engine oil, and a backup system of kerosene heaters and an ether injector.
