CHIGOE ASW TESTS AT NORFOLK, USN BRIEFING

• Document Type: FOIA
• Collection: FOIA Collection
• Document Number (FOIA) /ESDN (CREST): 05752609
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 3
• Document Creation Date: March 9, 2023
• Document Release Date: February 10, 2021
• Case Number: F-2011-01575
• Publication Date: November 15, 1966

Approved for Release: 2021/01/11 C05752609
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ORD-4912-66
15 NOV I9k6
MEMORANDUM FOR: Director of Research and Development
SUBJECT: CHIGOE ASW Tests at Norfolk, USN Briefing
1. On 7 and 8 November the CHIGOE Active Magnetics
and SD5 Infrared Systems were tested against the SS272,
"Redfin," a conventional fleet submarine. The purpose
of the test was to evaluate their potential for ASW,
with emphasis on the Active Magnetics approach which
had, heretofore, only been used over land. The prelim-
inary results are most encouraging, in that real-time
detections were made with the target submerged, under
realistic operating conditions. Final test results will
require two to three weeks for data reduction and IR cor-
relation. USN was briefed on the preliminary results.
2. The CHIGOE systems were installed in the ORD
P2 test aircraft and brought to Norfolk NAS on Sunday,
Nov 6. On the 7th, an early morning coordination session
was conducted on board the Redfin, which then departed
for its operating area off the coast. At approximately
1130 we overflew the Redfin on the surface, near Chesa-
peake Light, at the entrance to the Bay ship channel.
Enough runs were made at different altitudes and cross-
ing angles to record characteristic Active Magnetic
responses for later 'analysis, and to confirm that the
real-time readout was reasonably effective. Because
this is the largest (328 ft.) target we have attempted
so far, there was and still is some doubt that the spa-
tial filtering we employed was optimal.
SE RET
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3. At about 0100 on the 8th, we located the Redfin
on the surface about 200 miles east of Chesapeake Light,
in 1500 fathoms of water. Weather was clear, sea normal
with large swells, water temperature 72�F. Runs were
made at altitudes from 300 to 3000 ft. above the sur-
face, while the �Redfin went through a series of planned
maneuvers at periscope depth, 100, 200, and 300 ft.
Visual contact was kept through the use of air-dropped
and underwater-launched floating flares, and through the
employment of running lights and the Grimes lamp while
submerged. Visual contact was lost at the 300 ft. depth,
but a flare was dropped on the basis of the Active Mag-
netics alone, which proved to have been accurate when
the target surfaced.
4. The detection correlation appeared generally
good at slant ranges of well over 1000 ft. (target at
300 ft., altitude 700 to 750 ft.). Data reduction alone
will tell us how good it really was, as there were known
spurious signals in the record from a newly installed
digital clock and from aircraft UHF transmissions.
5. On 10 November Mr. and I briefed Admirals
Gaylor, Michaelis, and Dobie and �their staffs on the
preliminary test results, and on the system operating
principles. This briefing was very well received,
Admiral Dobie in particular being most anxious that we
should continue to feed information as the ASW work
develops. The consensus of the ASW people there present
was that present MAD gear is limited to 600-1000 ft.
slant ranges, and that it has no real search potential
for the future. The latest MAD system (ASW-81) will be
a 1000 ft. system at best, in operations.
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6. We made it clear that there was real danger in
extrapolating from our present crude prototype to a com-
plete new ASW technique better than MAD, and that we
still have a tremendous amount of R&D to accomplish.
This was accepted, but full USN cooperation in future
tests was guaranteed on the basis of apparent good
results in this first trial and on the previously demon-
strated success in our over-land tests.
DC/O/ORD/DD/S&T
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