Bearcat in the Chesapeake: Navy’s underwater investigation of a prototype fighter aircraft

Nov. 2, 2021 | By George Schwarz, Underwater Archaeologist, Naval History and Heritage Command
Grumman’s F8F Bearcat was lightweight fighter designed to operate from smaller naval aircraft carriers and had a higher rate of climb than its predecessor, the F6F Hellcat. Prototypes were tested starting in 1944, but they were not ready in time to see action in World War II. Noted for their speed and agility, postwar Bearcats became a significant fighter for the US Navy and Marine Corps, and the French utilized them during the French Indochina War (1946-1954). The Bearcat F8F-1 was fitted with a Pratt and Whitney Double Wasp two row, 18-cylinder radial engine and four .50-caliber guns. The wings were designed to fold upward to reduce its carrier footprint, and it is the first US naval fighter to employ a bubble canopy. A unique feature on the test model (XF8F-1) was the exploding wingtips. Three feet of the outboard wing tips were designed to blow off if the pilot exceeded 8.5 Gs, which would prevent total wing failure. This feature did not make it into production aircraft, however, as engineers were unsuccessful in making the wing tips blow off simultaneously.
XF8F-1 Bearcat wings folded
XF8F-1 Bearcat wings folded
XF8F-1 Bearcat wings folded
XF8F-1 Bearcat wings folded
XF8F-1 Bearcat wings folded
Photo By: National Archives
VIRIN: 210716-N-N0147-0002
 
In July 2021 the Naval History and Heritage Command (NHHC) and the Naval Oceanographic Office (NAVOCEANO) revisited the site of what is believed to be the remains of the original prototype Bearcat fighter aircraft (XF8F-1) in the Chesapeake Bay. The aircraft wreck, which was discovered as part of NHHC’s NAS Patuxent River Historic Aircraft Survey, was first inspected as a candidate for the XF8F by NHHC and Institute for Maritime History (IMH) in 2017. The dimensions and observable features matched those of a prototype Bearcat, one of two manufactured for testing at NAS Patuxent River.

The first of these XF8F’s, Bearcat 90460, was piloted by Lt. (j.g.) David Loyd Mandt during a gunnery test mission over the Chesapeake on March 18, 1945. Mandt was an experienced pilot with over 935 hours of flight time, and on the second flight of the day was test firing the wing machine guns, of which three firing runs were observed by personnel from Armament Test to be without incident. The airplane then passed out of field of view to the south. When Mandt did not return from his mission at 3:45 p.m. a search was initiated but the Navy never found the aircraft. An oil slick in the vicinity of the incident was observed, and a seat cushion, oxygen bottles, and a glove with Mandt’s name on it were recovered. An attempt was made to recover materials with a grapple the following day but only a portion of the engine, which was likely thrown from the aircraft frame during impact, was produced. Mandt was never found and the cause of the crash was never determined. The aircraft was reported demolished and further searches were not successful.

In 2015 and 2016, NHHC conducted archival research into several 1940s and 1950s aircraft that were lost and never recovered by the Navy as part of an effort to locate and identify sunken military aircraft in the Chesapeake Bay. One of these aircraft was XF8F-1 Bearcat 90460; but like other 1940s accident reports, an accurate location for the crash was missing. Remote sensing surveys undertaken by NHHC and IMH in 2016 and 2017, along with review of charted wrecks and obstructions, uncovered several aircraft crash candidates in the Chesapeake Bay. One of these had been charted as part of a NOAA hydrographic survey of the Bay in the 2010s, and roughly matched the general location of the last known sighting of the Bearcat. A side scan survey in 2017 revealed prominent aircraft features consistent with the size of a Bearcat, and IMH diver investigation confirmed the dimensions were accurate, and that the engine appeared to be missing. Other features consistent with the XF8F, including the location of the air intake on the wing’s leading edge, and the size and shape of the cockpit, were recorded. The bubble canopy was missing, and the cockpit was filled with sediment.

In July of 2021, NHHC conducted a focused remote sensing survey of the suspected Bearcat 90460, using side scan sonar, multibeam echosounder, and marine magnetometer. These data will be used as baseline information to assess and monitor its condition, create a map of the wreck site, and determine if ferrous materials (specifically the engine) are present.

 
 
Dr. George Schwarz and Agustin Ortiz deploy the side scan sonar from NHHC research vessel.
Dr. George Schwarz and Agustin Ortiz deploy the side scan sonar from NHHC research vessel.
Dr. George Schwarz and Agustin Ortiz deploy the side scan sonar from NHHC research vessel.
Dr. George Schwarz and Agustin Ortiz deploy the side scan sonar from NHHC research vessel.
Dr. George Schwarz and Agustin Ortiz deploy the side scan sonar from NHHC research vessel.
Photo By: Blair Atcheson
VIRIN: 210716-N-N0147-0003
Multibeam surveying over the suspected XF8F Bearcat
Multibeam surveying over the suspected XF8F Bearcat
Multibeam surveying over the suspected XF8F Bearcat
Multibeam surveying over the suspected XF8F Bearcat
Multibeam surveying over the suspected XF8F Bearcat
Photo By: Blair Atcheson
VIRIN: 210716-N-N0147-0004
NHHC side scan sonar image of the aircraft on the seafloor.
NHHC side scan sonar image of the aircraft on the seafloor.
NHHC side scan sonar image of the aircraft on the seafloor.
NHHC side scan sonar image of the aircraft on the seafloor.
NHHC side scan sonar image of the aircraft on the seafloor.
Photo By: Blair Atcheson
VIRIN: 210716-N-N0147-0005
In addition, NHHC and NAVOCEANO divers visited the site to inspect and record additional features present on the wreckage. Although fairly intact given its violent crash into the Bay, portions of both wings are missing, wing framing is exposed, one tail stabilizer is crushed, and the wreck is partially ensnared by fishing nets and cloth. The aircraft skin is covered with marine growth in most places, but the Bearcat sits upright on the seafloor. Although the cockpit is open and full of sediment, the windshield is remarkably intact. The Pratt and Whitney engine appears to have separated from the aircraft during impact, and was likely found in the sonar data approximately 60 ft. from the fuselage. Additional debris was found in the vicinity, but has not yet been inspected or verified whether it belongs to the fighter. Further site recording during this ongoing investigation will help researchers develop a better understanding of the aircraft condition and nearby components in the debris field.
 
NHHC vessel positioning divers over wreck site.
NHHC vessel positioning divers over wreck site.
NHHC vessel positioning divers over wreck site.
NHHC vessel positioning divers over wreck site.
NHHC vessel positioning divers over wreck site.
Photo By: Blair Atcheson
VIRIN: 210716-N-N0147-0006
George Schwarz prepares to enter the water with video equipment while NHHC Reservist diver Joe Harvey gives an okay signal to topside.
George Schwarz prepares to enter the water with video equipment while NHHC Reservist diver Joe Harvey gives an okay signal to topside.
George Schwarz prepares to enter the water with video equipment while NHHC Reservist diver Joe Harvey gives an okay signal to topside.
George Schwarz prepares to enter the water with video equipment while NHHC Reservist diver Joe Harvey gives an okay signal to topside.
George Schwarz prepares to enter the water with video equipment while NHHC Reservist diver Joe Harvey gives an okay signal to topside.
Photo By: Blair Atcheson
VIRIN: 210716-N-N0147-0007

Appreciation goes to Point Lookout State Park for hosting NHHC’s vessel during the two weeks of survey and diver investigation; IMH for volunteering considerable dive, survey, and boat time; and NAVOCEANO for supporting the 2021 Navy diving mission.
 
NAVOCEANO hydrographer Billy Hauer enters the water with survey gear.
NAVOCEANO hydrographer Billy Hauer enters the water with survey gear..
NAVOCEANO hydrographer Billy Hauer enters the water with survey gear.
NAVOCEANO hydrographer Billy Hauer enters the water with survey gear.
NAVOCEANO hydrographer Billy Hauer enters the water with survey gear..
Photo By: George Schwarz
VIRIN: 210716-N-N0147-0008
Divers inspect the after end of the aircraft’s cockpit
Divers inspect the after end of the aircraft’s cockpit
Divers inspect the after end of the aircraft’s cockpit
Divers inspect the after end of the aircraft’s cockpit
Divers inspect the after end of the aircraft’s cockpit
Photo By: George Schwarz
VIRIN: 210716-N-N0147-0009
Exposed wing frame elements on the wreck
Exposed wing frame elements on the wreck
Exposed wing frame elements on the wreck
Exposed wing frame elements on the wreck
Exposed wing frame elements on the wreck
Photo By: George Schwarz
VIRIN: 210716-N-N0147-0010
Beneath the marine growth, the aircraft’s windshield is intact.
Beneath the marine growth, the aircraft’s windshield is intact.
Beneath the marine growth, the aircraft’s windshield is intact.
Beneath the marine growth, the aircraft’s windshield is intact.
Beneath the marine growth, the aircraft’s windshield is intact.
Photo By: George Schwarz
VIRIN: 210716-N-N0147-0011