This is a seven-cylinder Jacobs R-755 radial engine that was built during the Second World War. It’s now been significantly modified, and turned into a clock with one halved propeller becoming an hour hand, and the other becoming the minute hand.
The Jacobs Aircraft Engine Company would build 14,746 examples of the R-755 with the first one successfully running back in 1933. It would power the (Boeing) Stearman Model 75 which was one of the most prolific trainers for pilots entering WWII.
This Jacobs R-755 radial engine has been turned into a clock with one halved propeller becoming an hour hand, and the other becoming the minute hand.
History Speedrun: The Jacobs R-755 Engine
The Jacobs R-755 radial engine, also known by its official designation L-4, was developed and manufactured by the Jacobs Aircraft Engine Company. It was introduced in 1933, it’s a 7-cylinder, air-cooled radial engine displacing 757 cubic inches (12.4 liters).
It was designed primarily for reliability, simplicity, and bullet-proof performance, and as a result it quickly became popular among aircraft manufacturers of the day in both civilian and military aviation applications.
The R-755 was initially rated at 225 bhp and it weighed 505 lbs (229 kgs), by the standards of the time it provided a solid power-to-weight ratio ideal for smaller commercial and private aircraft. The engine gained national recognition when it was selected to power the Beechcraft Model 17 “Staggerwing,” – an aircraft that’s been called the Learjet of its day.
The Jacobs R-755 found extensive use during World War II, powering a number of significant aircraft including the Boeing-Stearman PT-18 Kaydet training biplane and the Cessna AT-17 Bobcat, a twin-engine trainer. During this time period, production increased to meet wartime demand – Jacobs built almost 15,000 examples of the R-755 at their factory in Pottstown, Pennsylvania.
It has now been affixed to a tubular steel stand measuring 48″ x 48″ and fitted with six nylon caster wheels.
After the war the R-755 continued on in its popularity for a time – its lightweight design coupled with its ubiquity saw it to remain relevant well into the 1950s and 1960s. In fact, production and refurbishment of the R-755 continued into the 1970s, and there are many warbird mechanics today who can service and rebuild them.
The Jacobs R-755 Radial Engine Clock
The engine you see here is a Jacobs R-755 that was said to have been originally fitted to a Cessna AT-17 Bobcat “Bamboo Bomber” in 1942 during WWII.
It has now been affixed to a tubular steel stand measuring 48″ x 48″ and fitted with six nylon caster wheels. The engine was stripped and refinished, and it now presents in close-to-new condition throughout.
The clock mechanism was made in Belgium, it sites inside a composite frame and is installed within the crankcase, it’s powered by a 120 Volt, 60 Hz high-torque electric motor with an impulse-type controller at minute intervals. Impressively, it even has an automatic adjustment system for daylight saving time.
The clock mechanism was made in Belgium, it sites inside a composite frame and is installed within the crankcase, it’s powered by a 120 Volt, 60 Hz high-torque electric motor with an impulse-type controller at minute intervals.
Two wooden Sensenich propellers were used, each damaged in a prop strike incident. One side has now been removed from each to allow them to act as the clock’s hour and minute hands. The minute hand has an 86″ diameter swing while running, and the hour hand swings in a 72″ arc.
This highly-unusual clock is now being offered for sale out of Hampshire, Illinois. It’s named “Times Flies” for obvious reasons, and it’s being sold at no reserve.
Images courtesy of Bring a Trailer
Articles that Ben Branch has written have been covered on CNN, Popular Mechanics, Smithsonian Magazine, Road & Track Magazine, the official Pinterest blog, the official eBay Motors blog, BuzzFeed, Autoweek Magazine, Wired Magazine, Autoblog, Gear Patrol, Jalopnik, The Verge, and many more.
Silodrome was founded by Ben back in 2010, in the years since the site has grown to become a world leader in the alternative and vintage motoring sector, with well over a million monthly readers from around the world and many hundreds of thousands of followers on social media.
