Earhart Arm Length: Mathematical Analysis

Earhart Project Research Bulletin #87
Artifact Research Update #2
May 26, 2020

A bi-weekly report to major TIGHAR supporters and contributors to the 2020 Artifact Research Fund.

Introduction

It is early March, 1937. The Electra is being prepared for Earhart’s first world flight attempt. Amelia and navigator Harry Manning are sitting on a plywood navigator’s table installed above the transmitter on the floor. To install the table, the transmitter has been temporarily removed. The unplugged end of the internal feed line is visible by Earhart’s left hand. It has a stranded center conductor covered with a rubber jacket. Artifact 2-2-V-1a is a single tinned copper filament in cloth insulation, possibly originally covered in a rubber jacket.

Special thanks to sharp-eyed TIGHAR Researchers Dan Brown and Bill Davenport who spotted this important detail, and to radio historian Norm Chipps who identified the type of cable.

As reported in Artifact Research Update #1, we have confirmed that Artifact 2-2-V-1a is the type of wire used as internal radio feed-line on aircraft circa 1937, and is unlike wire used during World War II. Further research has now determined that if the wire is from NR16020 it is not the internal feed line from the aircraft’s dorsal vee antenna to the transmitter. A photograph that luckily caught the transmitter feed line at a moment when it was unattached shows it to have been unlike Artifact 2-2-V-1a.

If Artifact 2-2-V-1a is from NR16020 it is probably internal feed line from the receiver under the copilot seat. Such wire would typically be identical to the artifact. If the wire is not from NR16020 there must be a rational explanation for where it came from and how it became entangled on a piece of airplane debris.

We’re testing three hypotheses:

Hypothesis #1: The wire and the sheet of aluminum in which it was entangled are debris from Earhart’s Electra.

Hypothesis #2: The wire and the sheet of aluminum in which it was entangled are debris from some other aircraft.

Hypothesis #3: The wire and the sheet of aluminum in which it was entangled are unrelated and their entanglement is pure coincidence.

Our best clues to determine which hypothesis is correct are:

The history of the area where the artifacts were found.
The condition of the artifacts when found.

Location

TIGHAR has found more than a dozen aircraft-related artifacts on Nikumaroro. With the sole exception of 2-2-V-1 and 2-2-V-1a, all were discovered in the abandoned government station and village.

This 1953 aerial photo shows the village on Nikumaroro at its peak development. The landing channel was blasted through the reef in 1963 when the island was evacuated due to severe drought.

All of the aircraft-related artifacts found in the abandoned village were in locations undisturbed since the island was evacuated in 1963, and all had been re-purposed for local use (combs, fishing lures, etc.) or are scraps from such activity. The only electrical wire we’ve found was in or near the island radio shack and is of WWII or later vintage.

Artifacts 2-2-V-1 and 2-2-V-1a were found near the Co-op Store, 25 meters (82 feet) inland from the normal high tide line. During TIGHAR’s first expedition to Nikumaroro in 1989, we did a visual and metal-detector search of the entire beachfront near the landing channel. Two metal artifacts were found, a broken table knife and a Ronson cigarette lighter, both far smaller metal-detector targets than a sheet of aluminum and 34 inches of copper wire. It appears safe to conclude 2-2-V-1 and 2-2-V-1a were not present when the beachfront was searched in 1989.

In 1989, dense vegetation lined the beachfront and the head of the landing channel was marked with a 20 foot tall concrete beacon.

Nearby, behind the vegetation, the Gardner Co-Op Store stood intact.

The 1991 storm surge had knocked down the Co-Op Store.

In 1991, the beachfront vegetation was gone and all that remained of the landing beacon was its base and a few bent pieces of re-bar.

The aluminum sheet and entangled wire were on the surface amidst the wash-up from the storm about 2 meters (6.5 feet) from the collapsed roof of the Gardner Co-op Store and 25 meters (82 feet) inland from the normal high tide line.

The artifacts could not have come from the village via back-wash from a wave because they would be blocked by the store, and they did not come from the interior of the store because it was inspected in 1989 and contained nothing but a bed frame and a mummified cat.

Conclusion

The history of the specific location where 2-2-V-1 and 2-2-V-1a were found strongly suggests the artifacts washed ashore in February 1990 during tropical cyclone “Ofa.”

Condition of the Artifacts

An examination of 2-2-V-1 by metallurgists at Massachusetts Materials Research found the edges of the sheet “were extensively damaged by post-fracture mechanical rubbing and corrosion. This is expected of aluminum and its alloys when exposed to seawater and wave action, especially if that exposure has been prolonged, as would be the case for an aircraft fragment pre-dating World War II. Coral growth on this artifact is consistent with prolonged exposure.”

These features set the artifact apart from pieces of aircraft aluminum found in the abandoned village, none of which exhibit evidence of mechanical rubbing or coral growth.

Both sides of the aluminum sheet exhibit corrosion and numerous patches of coral growth indicating prolonged submersion in sunlit seawater.

The wire found entangled in the metal sheet is missing any rubber jacketing and most of the insulation, suggesting long exposure to an abrasive environment.

Conclusion

Artifact 2-2-V-1 was submerged in sunlit seawater and mobile in an abrasive environment long enough for coral to grow on its surface and its edges to be worn smooth. Artifact 2-2-V-1a was mobile in an abrasive environment long enough to lose most of its insulation. How long the two objects had been joined together is unknown, but one or both must have been mobile in the same environment to become entangled.

Returning to the Three Hypotheses

Hypothesis #1. The wire and the sheet of aluminum in which it was entangled are debris from Earhart’s Electra.

Hypothesis #1 has the advantage of being in agreement with Occam’s Razor: “Entities should not be multiplied without necessity.” The simplest explanation is that both artifacts are debris from the same source – a 1930s-vintage aircraft. Their condition is consistent with them having made the journey southward along the reef flat from where Earhart’s Electra broke up to where the artifacts were found. The known facts support Hypothesis #1.

Hypothesis #2. The wire and the sheet of aluminum in which it was entangled are debris from some other aircraft.

The artifacts came from the ocean, not the village. Aluminum and wire do not float, so they did not come from an aircraft wreck on another island. Hypothesis #2 is not supported by the available evidence and can be dismissed.

Hypothesis #3. The wire and the sheet of aluminum in which it was entangled are unrelated and their entanglement is pure coincidence.

For Hypothesis #3 to be correct the wire must have a non-aviation source. That type of single-filament wire was used in other radio applications in the 1930s, so it is possible that obsolete feed line was used somewhere in the U.S. Coast Guard LORAN station built at the island’s southeastern tip in 1944 and shut down in 1946. After WWII, island residents salvaged material from the Coast Guard facility. Radio wire recovered by TIGHAR from the island’s radio shack is WWII-vintage shielded coaxial cable possibly taken from the abandoned Coast Guard facility. We’ve found no wire like 2-2-V-1a in the ruins of the LORAN station nor in the village, but that doesn’t mean such wire did not exist and was not salvaged.

However, for the wire to become entangled on 2-2-V-1 it must be in the same place as the aluminum sheet and one or both objects must be in motion. We know 2-2-V-1 was in the ocean or on the reef flat until shortly before we found it in 1991, so the wire must have somehow also been in the water. There are no facts to support Hypothesis #3 but it cannot be categorically dismissed.

At this point in our investigation, there appears to be a high probability Artifacts 2-2-V-1 and 2-2-V-1a are debris from NR16020. We’ll next consider what that tells us about the aircraft’s fate.

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