Back in WW I, the aeroplane had only been newly invented, and was not yet well understood from an aerodynamic point of view, or lightweight structures, or power-packs. To lift much more than a man with some machine guns you needed some serious power, and some serious wing area. The wing area issue had been addressed earlier by tri-plane designs, but this limited the maximum speed at which planes could travel. A shift to bi-plane design required a longer span or aerofoil section width, both enabled by the LUSAC-11 with a large 415.5 sq.ft wing area. Power was provided by a 425 Packard-developed V12 Liberty engine. Original orders stood at 3,525 units to be assembled by the body-builders at Packard, Brewster and Fisher-Body (later part of General Motors), however WW I ended earlier than the expected production schedule, and in the end, only 30 planes were produced, in total, including prototypes.
The link between the aeroplane and the car is the V12 engine.
As the USA entered WW I against Germany the Aircraft Production Board summoned representatives from the Auto industry to develop a lightweight, high power engine for aircraft. To cut a long story short, the Liberty V12, designed by the Packard motor company was the outcome. The engine was produced by multiple engine suppliers, including Packard, Marmon and Lincoln motor companies. The engine was or 27 litre swept capacity (1649 CID). Though not used in automobiles, the production technologies, tooling and engineering development expertise allowed these luxury marques, and additionally Cadillac, to produce V12 designs capable for automobile use.
The 1922 Packard Twin-Six 3-35 Roadster shown here was a development of the first automobile production V12 produced. First produced in 1916, this first series ran until 1923.
In three series between 1916 and 1923, Packard built slightly more than 35,000 Twins, including numerous chassis for custom bodies. The Twin Six was the chief reason why, when the wealthy ordered a custom-bodied car, they tended to choose a Packard chassis.
Jesse Vincent, Packard's chief engineer, liked the 12-cylinder layout for three reasons: performance, smoothness, and silence. "A six-cylinder motor is theoretically in absolutely perfect balance," he wrote. "This is because the vibratory forces due to the rise and fall of one piston are neutralized by equal and opposite forces due to another...Now it is only possible to cancel out forces in this way if they are tied together strongly."
This meant a heavy crankcase and crankshaft and a rigid flywheel. But a Twelve or "Twin Six," Vincent continued, would provide the same rigidity and smoothness with less piston, crankcase, flywheel, and crankshaft weight -- and provide more horsepower and torque, to boot. He preferred a V-12 to a V-8 because a V-8 would require a wider frame, larger turning radius, and more complicated steering gear.
The Twin Six engine duly embodied the above principles, with two banks of L-head cylinders set at a 60-degree angle (versus 90 degrees in Cadillac's V-8). This allowed accessories to be bolted just below the frame, where they were protected from road hazards, while keeping the valves accessible.
Delivering 85 horsepower at 3,000 rpm, a bore and stroke at 3.00 × 5.00 inches resulted in a displacement of 424 cubic inches. Rockers were eliminated, with a separate cam for each valve, and all valves were located inboard of the cylinder blocks. A short, light crankshaft ran in three main bearings.
The car shown here is a 1922 Series-3 car, bodied as a Roadster.
The Packard-Le Père LUSAC-11 (1917) and Packard Twin-Six 3-35 Roadster (1922) have both been modelled in Lego miniland-scale for Flickr LUGNuts 79th Build Challenge, - "LUGNuts goes Wingnuts", - featuring automotive creations inspired by, named after, or with some connection to aviation.
