Aero Telemetry: Motor Testing

Showing posts with label Motor Testing. Show all posts

Thursday, December 21, 2017

Lawrance L-5 Restoration

The Lawrance L-5, 5-cylinder radial engine. A very rare and relatively unknown radial engine developed by Charles Lawrance, whose company Lawrance Aero Engines Ltd. was purchased by Wright Aeronautical in 1923. Lawrance then went on to develop the extremely successful Wright Whirlwind for which was used by Charles Lindbergh and Amelia Earhart on their record setting long distance flights.
This specific engine is unique in that it was designed to operate mounted vertical as a auxiliary power unit on airplanes designed to operate from remote locations or over the ocean. A Martin PBM Mariner used during World War Two may have used this engine to provide enough 28VDC power to start one of the main engines while at some remote South Pacific island. Incredibly compact and smooth running, the L-5 produces about 35 HP.
After the War, airplane enthusiasts obtained a few L-5 engines as surplus and attempted to convert them for use on small ultralight airplanes. There were several issues that made the conversion problematic. The oiling system and sump were setup for vertical operation and there was no provision for mounting and driving a propeller (as in thrust bearings or splined prop shaft)
These issues added some complexity to the rebuild, however using a pusher type propeller in an "airplane-style" mount and some modification to the oiling system allowed the Aero Telemetry team to complete this rare radial restoration in less than a month...it is most likely the only reliable running example in the world.

Thursday, February 6, 2014

Designing the XF-11

Completing the XF-11 airplane in less than 3 months proved to be one of the biggest challenges for the Aero Telemetry team. Joe and his team had to design, build, and test a custom set of hydraulic, retractable landing gear, fabricate an ultra-strong airframe, coordinate a complex airborne flight control system, and integrate all of these systems seamlessly to overcome the aerodynamic stresses of high speed and heavy payload.

The primary scale models for The Aviator were the Aero Telemetry XF-11 and the H-4 Hercules or Spruce Goose. Both of these airplanes would be designed and fabricated over a period of 3 months by Joe Bok and his Aero Telemetry team. At the time, they were the worlds largest (unmanned) flyable scale aircraft ever flown for a big budget Hollywood movie.

The aerodynamic profile of the wing, engine thrust-lines, CG location, main airfoil angle of attack, incidence angles (between wing and horizontal stabilizer), counter-rotating propellers, and vertical stabilizer offset angles were just a few of the critical design criteria addressed and implemented correctly by the Aero Telemetry engineering design team. All these specific details contributed directly to the success and margin of safety exemplified in all the flights of the Aero Telemetry XF-11.