COMMENTS RELATIVE TO INFRARED RADIATION THERMOMETER WORKSHOP 



by John \V. Reintjes, U.S. Bureau of Commercial Fisheries, 

 Beaufort, North Carolina 



Determination of sea surface temperatures with an airborne infrared radiation 

 thermometer was initiated at the U. S. Bureau of Commercial Fisheries Biological Labora- 

 tory, Beaufort, N. C, in August 1963. The area between Cape Hatteras and Cape Fear, 

 North Carolina, out to the edge of the Continental Shelf, was the accepted responsibility of 

 the laboratory as part of a cooperative program. 



An infrared radiation thermometer (Barnes Engineering IT-2), a strip recorder 

 (Varian G-llA), and an inverter (ATR, Model RSF) were purchased. A test flight in a U.S. 

 Marine Corps Fairchild C-119 was unsatisfactory because of excessive fluctuation of the 

 read-out directly from the dial or by the recording stylus. The sensing head was mounted 

 vertically in the flare tube with a sponge rubber adapter or hand -held out the rear observa- 

 tion hatch. Neither location gave acceptable results. Test operations on the ground indica- 

 ted sonic interference from the aircraft. 



A test flight was made in a U. S. Coast Guard Grumman "Albatross" (UF2G) on 

 October 14, 1963 to compare the results of our instrument (IT-2) with an IT-1 from Sandy 

 Hook Marine Laboratory. Side by side operation showed the IT-2 unable to cope with air 

 stream conditions that permitted satisfactory operation of the IT-1. The instrument was 

 bench checked and then ground checked in a Douglas DC -3 aircraft. These checks demon- 

 strated the fluctuations were due to air stream interference in the sensing head. Apparently 

 this is an intrinsic condition in the earlier models of the IT-2 with an unsealed cavity. 

 Successful in-flight operation required installation free of e.xcessive turbulence or air stream 

 interference. 



Successful operational flights were completed on November 27, December 20, 1963; 

 January 20, March 17, and April 17, 1964 in U. S. Coast Guard UF2G "Albatross". On all 

 flights the sensing head was mounted on a bracket on the frame of the rear left hatch inside 

 the fuselage. The detector was directed at the sea surface from 30° to 45'' from normal. 

 Needle and recording stylus fluctuated less than l"C. during normal flight attitudes. Occasion- 

 ally, during skidding turns, variations, apparently due to turbulence, would exceed 2°. A tem- 

 porary baffle along the leading edge of the hatch opening shielded the head from air stream 

 interference and improved the trace. Although this installation is not wholly satisfactory, it 

 is expedient unless structural modification and a permanent mounting are made in the air- 

 craft. We have considered a contoured hatch or shield with a small opening for sighting the 

 detector. At the present time, drift bottles and seabed drifters are thrown overboard from 

 the hatchway and as yet we have not met the requirements for an open but sheltered port. 



Radio communication with Diamond Shoals and Frying Pan Shoals Lightships was 

 established during all flights for surface water temperatures while the aircraft was flying 

 over or in sight [range] of the vessels. In general the temperatures reported by the vessels 



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