The dart was attached to 300 meters of float- 

 able polypropylene line with a small section of 

 cable to reduce chafing. For a drop from 60 to 

 90 meters altitude, with this length the line is 

 still leaving the aircraft after the dart has hit. 

 This results in the line laying smoothly on the 

 surface and with little or no pull on the instru- 

 ment package. The instruments can then be al- 

 lowed to free-fall or be lowered by parachute. 



The line was originally placed on a faking 

 board similar to those used with a Lyle lifesaving 

 gun in the late 19th and early 20th centuries 

 (Figure A-5) (Lyle, 1878). The board was 

 mounted vertically on the lowered rear ramp of 

 a C-130 aircraft in flight. Over 300 meters of 

 bne feed off the board in less than five seconds. 

 Stress problems developed with the board con- 

 cept when the bottom layers were reached. A 

 much improved method of deploying the line was 

 developed by Farmer (1977) (Figure A-6). 

 The line was packed in bundles secured by rubber 

 bands. All of the bundles were then placed in a 

 parachute pack which was opened when the dart 

 was thrown from the rear ramp of the C-130, 

 thereby allowing the bundles to smoothly unravel 

 one at a time. The instruments can then be 

 launched just before the last of the bundles un- 

 ravel. 



A final instrument package has not been devel- 

 oped for the tagging system. In tests, we have 

 used a modified sonobuoy as an expendable 

 transmitter. 



In addition to ten test drops on icebergs in 

 1975 and 1977, several tests of the system have 

 been conducted over land at the Coast Guard 

 Elizabeth City Air Station. Drops were made 

 from 61 meters at an airspeed of 130 knots (67 

 m/s) and ice was assumed to have an index of 

 penetrability of 2.5. The 1975 test gave a pene- 

 tration of 1.1 meters and the 1977 test (Figure 

 A-7) had a penetration of 0.76 meters. Other 

 penetrations of the iceberg were not accessible 

 from a small boat or were under water. Results 

 are as follows : 



(a) Accuracy — After several practice runs, 

 pilots can hit an iceberg as small as 20 

 meters on a side 75 percent of the time 

 from 61 or 91 meters altitude. 



(b) Line Handling — The parachute pack line 

 handling system developed by Farmer 

 does a superior job of deploying large 

 quantities of line without kinks or tangles. 



(c) Penetration — The dart which was used in 

 the tests on icebergs in 1975 and 1977 had 

 a predicted penetration characteristic as 

 given in Table 1 (Young, 1972). 



(d) Holding Strength — The holding power of 

 the 1977 test with 0.76 meter penetration 

 exceeded the strength of a 1.25 cm poly- 

 propylene line which is approximately 

 5,000 pounds. 



Further development of an expendable instru- 

 ment package is planned, permitting the tracking 

 of icebergs both from the surface and from 

 satellite. 



REFERENCES 



Brooks, L. D., 1977 : Iceberg and current drift using the 

 NIMBUS-6 satellite. Proceedings, The 9th Annual 

 Offshore Technology Conference, Houston, Texas, 2-5 

 May 1977. 



Cheney, L. A. and Soule, F. M., 1951 : International Ice 

 Observation and Ice Patrol Service in the North 

 Atlantic Ocean (Season of 1950), Coast Guard Bulle- 

 tin No. 36. 



Farmer, L., 1977 : Personal communication. 



Hayes, R. M., Robe, R. Q. and Scobie, R. W., 1975: 

 Iceberg tagging and tracking project, IIP 1974, un- 

 published Coast Guard report. 



Kollmeyer, R. C, 1966: Oceanography of the Grand 

 Banks Region of Newfoundland in 1965, U.S. Coast 

 Guard Oceanographic Report No. 11, CG-373. 



Lenczyk, R. E., 1965: Report of the International Ice 

 Patrol Service in the North Atlantic Ocean (Season 

 of 1964), Coast Guard Bulletin No. 50. 



Lyle, D. A., 1878 : Report on Life-Saving Ordnance and 

 Appurtenances, Ordnance Department, U.S. Army, 

 Government Printing Office, Washington, D.C. 



Redfield, W. O, 1845 : On the drift ice and currents of 

 the North Atlantic, extracted from the American 

 Journal of Science, Vol. 48, B. L. Hamlen, New Haven, 

 CT. 



Young, C. W., 1972 : A parametric study of an ice pene- 

 tratine sono-buoy vehicle, Sandia Laboratories Report 

 SC-DR-72 0379. 



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