The Fort MacArthur Museum Association: Sperry Searchlight Project

60" Sperry Searchlight Project
What would you do with a 800-million candlepower flashlight?

The light being restored was purchased in Santa Rosa California. The light and generator had been sitting in a field probably for over 10 years. Putting this unit back in operation has been a rewarding challenge to the restoration crew here at Fort MacArthur.

The light came pretty much intact, but a few very important parts were missing. The burner inside the light needed to be totally rebuilt. The carbon feed mechanism had frozen due to rust. The generator for this light should be a Sperry Searchlight Generator, but what we ended up with was a General Electric Searchlight Generator.

This unit was just as complete as the light, but it too was in need of a few important parts, like the distributor, and the battery charging generator. It was later found that after sitting so long, the generator's Hercules JXD 6 cylinder engine had frozen up, and would not turn over.

After two years of intense work, the Sperry Searchlight

1941 model Sperry Searchlight in use at
Fort MacArthur

was finally brought back to an in-service condition by the skilled work of our volunteers in time for its début at the 2003 Old Fort MacArthur Days event. since that time, the light has been used to announce the various special events at the museum. This has been a great way to promote awareness of the museum.

Here are some before and after pictures of the restoration progress.

Before

This is the burner assembly before restoration

After

This is the burner assembly after restoration

The Control Panel for the 1941 GE Generator

Control Panel restoration completed 2004

The light and generator had been sitting in a field probably for over 10 years.

Museum Director Stephen Nelson at the controls for
the first lighting of the restored light.

Continuing Projects

     General Electric GM-12 Generator Set
     60" General Electric Searchlight Project
     Time-Interval Bell for the Gun Pit
     60" Sperry Searchlight Project
     Battery Window Replacement Project

Carbon Arc Searchlight Facts:

The first 60 inch Searchlight was made by General Electric in 1893

Searchlights were produced for military use from 1932 to 1944 at a cost of $60,000 each!

Lamp Type: Carbon Arc (no light bulb!)

Candle Power: 800 Million

Effective Beam width: 5' plus

Effective Beam length: 5.6 miles

Effective Beam visibility: 28~35 miles

Generator Power: 15 KWV nominal - 16.7 KWV max. (15,000~16,700 watts D.C.)

Powered By: Inline 6 cyl. "Hercules"
Flathead Engine

Generator Engine Fuel: Gasoline (can also be run using Kerosene or Gasohol)

Combined Weight: 6,000 pounds (3 tons, or the weight of 3 Ford Mustangs combined!)

The beam is made by 2 carbon rods, one positive and one negative, arching within the focal point of a 60 inch parabolic mirror. As the rods "burn" they are automatically fed into the light. The rods last approximately 2 hours and are then replaced.

The flame that is visible during the lights operation, is not actually the source of the light, rather, it is a by-product, produced as a result of the electricity arcing between the 2 rods.

The flame is the rod slowly burning away as it is fed into the light. The arc draws 150 amps continuously at 78 volts and burns at over 3,000 degrees Fahrenheit. The power is supplied by the D.C. generator which was designed specifically for this purpose.

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