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(See page 392, March, 1931, Proceedings)
By Lieutenant (J. G.) H. P. McLean Connor, U. S. Naval Reserve.—With reference to the New York-Bermuda and return nonstop flight and answering Lieutenant Commander Fairland’s questions in order:
(a) The drift was determined constantly throughout the voyage (with the exception of the short night period) by the seaman’s eye, i.e., judging the direction and velocity of the wind at the surface from the state of the sea and thereby making due allowance for drift by the solution of a simple problem in trigonometry. (Note: The air speed meter and tachometer had been carefully checked prior to the flight and were accurate. Lieutenant Commander Fairlamb will also note from the navigation log the low altitude which was maintained.)
The only other check on the drift was by “sighting” on the vessels in the New York- Bermuda track as we left them astern. (Note: The drift “sights” obtained on the steamers checked to the degree with the method described above.)
(b) I believe I stated in my article that we carried three magnetic compasses but neglected to state which one was used to steer by. All three were Pioneer compasses. The earth inductor compass dial was used to steer by and worked perfectly for the entire flight thereby enabling the pilots to steer the course to a degree. The other two compasses were of the standard aircraft magnetic card type, (liquid) Pioneer type 56, graduated to every fifth degree. These were used only as stand-by compasses and for checking purposes, the deviation on each compass being known. We did not carry an aperiodic compass.
(c) I believe the plotting sheet reproduced on page 1065, December, 1930, Pro-
ceedings shows five single sun lines. This chart is marked “as used by the navigator” and is only intended as an example of the chart actually used for the purposes of publication, and does not contain all the sun lines taken on the flight, the others being omitted for the sake of clarity, and so that the chart might be easily understood by the layman. .
Actually each single line plotted was the resultant mean of four “sights” taken at intervals within a minute of time for each “sight.”
The term “position by observation” as marked on the plotting sheet is technically incorrect, as the sun lines of position were crossed by dead-reckoning latitude and assumed as “best” positions.
The writer stated in his article that the observations of the sun were calculated by line of position methods and used in conjunction with dead-reckoning navigation.
The octant used was a Willson-type octant with a bubble attachment. This instrument is a right-handed octant and the observations are made similar to those with an ordinary nautical sextant.
After long practice at sea and in the air, I found it convenient to use. My average error for sun observations is from one to three miles under favorable conditions. Some time prior to the Bermuda flight I conferred with Lieutenant Commander Weems, and after comparing notes he concurred in the opinion that it was more advantageous to stick to the instrument I was most familiar with than attempt to change to a different type of bubble octant. This also applied to navigational methods.
It is logical that only after considerable experience, can a navigator have the complete confidence necessary in order to be able to rely on his positions whether by dead reckoning or observation.
Shortly after obtaining an unlimited master mariner’s license in 1925 I became interested, for the purpose of ocean flying, in applying nautical navigation to aircraft in a practical way. A few short flights in which I struggled along with a bubble sextant without any great degree of accuracy soon convinced me that a good deal of practice would be necessary before I could reduce my errors to a minimum.
In 1927 I was anxious to make a Bermuda flight in order to establish a reputation as an aerial navigator. With this thought in mind I made a number of extended overwater flights ranging from 150 to 350 miles off shore, intercepting vessels whose position, true course, and average speed I had obtained by radio prior to taking off. After constant practice at frequent intervals I was finally able to reduce my error in determining drift by the seamen’s eye from 8 per cent to practically zero.
These interception flights were made on straight-away and triangular courses under nearly all weather conditions, with the exception of fog, with winds ranging from force zero to seven (Beaufort scale). Captain Davis and Captain Francis, commanders of the M.S. Bermuda and SS. Fort Victoria, respectively, will doubtless recall that on more than one occasion we intercepted their vessels approximately halfway to Bermuda and according to estimated time after encountering variable winds.
While serving on the 32,000-ton turbo electric liner California during 1928-29 in the Panama-Pacific run, I had ample opportunity to become experienced in the use of the bubble octant, supplemented by the above mentioned practice flights while in port. Referring to my workbook I find an average of five sets of astronomical observations taken per day over 75 per cent of days at sea, i.e., morning stellar, 8:00 a.m. sun, noon position (observations of the planet Venus, when visible), 4:00 p.m. sun, and evening stellar observations.
Referring to the Bermuda flight; taking the 10:39 a.m. sun line for example. This was the result of four “sights” taken at 10:37, 10:38, 10:39, and 10:40, respectively. In this case each sight was worked out separately. I disregarded the 10:37 and 10:40 lines and used the 10:38 and 10:39 sun lines as they worked out within a mile of each other, crossing the sun line with my D.R. latitude run up from my last known position, i.e., time of passing the SS. Fort
St. George. (You will note that I have marked the 10:39 sun line on the chart and gave the 10:38 sight for an example as calculated by H.O. 208.)
Two hours prior to taking off from New York we had received by radio the position, course, and speed of the SS. Fort St. George, and as we had intercepted her within a minute of our estimated time I felt we could rely on that position as being within a mile or so.
Obviously, this case would not always apply as only practical experience could guide the navigator in his judgment of assuming his “best” position or “fix,” and no hard and fast rules should be laid down.
On the recent Atlantic flight of the Columbia, in which I participated, we flew approximately 1,400 miles without obtaining observations. Part of this was “blind” flying and during the remainder of the night, when we were finally above the cloud level, the ship was tossed around in the rough air due to the winds of gale force rendering the bubble octant useless for that period. As there was no way we could check our drift during the night period I naturally had to estimate it by approximation. For almost two and one-half hours after sunrise, observations were useless due to the existing refraction; here again only practical experience could tell the navigator whether or not he could rely on his sights under such conditions. (I did not attempt to take observations during this period.) When I finally obtained a “fix” about 0940 G.C.T., October 10, after the sun’s bearing had changed sufficiently to give a fair angle, we were approximately 130 miles SSW., of our D.R. position, and the course was altered towards Land’s End, England, and Croydon, London. (Note: We had been allowing 40 degrees for drift during the latter part of the night; this was evidently insufficient.)
In this instance I obtained my “fix” by crossing the first sun line with the second, making due allowance for the true course and run between. (We were then maintaining a relatively low altitude and checking drift by my old reliable method.) I continued to obtain sun lines and “fixes” by crossing them until we finally made landfall slightly on our port hand, in clear weather, at 0340 G.C.T. This was the Scilly Islands.
Upon arrival in London the following day it was interesting to note in a London newspaper that the British steamer Virigilia had reported sighting us some 200 miles off Land’s End. They reported our position in latitude 49.08 north, longitude 10.25 west at 14.00 G.C.T., October 10. Upon checking back our own position on the chart for that time it was interesting to note that the difference between the steamer’s calculated position and our own was six miles. (This difference divided by the numbered of miles we had flown gives a very small percentage of error.) With reference to the method of checking drift I most decidedly would not recommend this method for inexperienced navigators, and I go as far as to say it would only be safe in the hands of experienced navigators. It was also my theory that it was necessary for an aerial navigator to obtain his training and background in practical experience as a navigating officer at sea before attempting difficult long overwater flights, and after my own experiences I am still of the same opinion. I believe it quite possible that experienced ocean navigators, after 100 hours flight training in actually navigating aircraft over water, would be able to cope with any problem which might confront them.
To attain accuracy the whole situation summed up is that “practice does make perfect.”
I agree with Lieutenant Commander Fair- lamb that the value of such flights adds little to that already accomplished other than for personal gain or ambitions. But the military value in the proof that such flights can be made without radio, as might be necessary in time of war, and still retain the ability to make perfect landfalls, is not to be ignored.
For instance, flight, without the aid of radio, from the Pacific coast to the Hawaiian Islands, thence to Gaum and the Philippine Islands, connecting up the naval bases, would be of tremendous importance to national defense in time of war.
I welcomed the low visibility and rain which was encountered within 100 miles of Bermuda, as it gave no opportunities for skeptics to believe that the island could have been seen had we been a few miles off our course.
Lieutenant Commander Fairlamb shows an expert knowledge of aerial navigation from the way in which he discusses the problems that confront navigators on difficult over-water flights, and I hope that the above comments may clarify some of the points he discussed.
Elements Contributing to Aerial Superiority
(See page 437, April, 1931, Proceedings)
By Commander R. K. Turner, U. S. Navy.—The award of the annual Naval Institute prize to an essay concerned with the importance and effectiveness of aircraft in warfare at sea is stimulating evidence of the position held by aviation in the American Navy. The author’s contention that vigorous defensive measures are necessary to permit the fleet to continue effective operations within its usual sphere will find ready response among the many officers who are familiar through daily routine with present conditions, so greatly changed in a decade.
We may agree with the central theme of the essay that it is desirable to evolve an efficient gun defense against bombing aircraft, since it is particularly in the case of first attacks that our defense in the air will be least effective. Time and altitude factors may easily permit enemy formations to deliver their first blows before being broken up by our fighter patrols. However, though the activities of such patrols cannot prevent initial thrusts, a vigorous air defensive will diminish the power of successive attacks, and therefore must not be neglected in prolonged and general sea actions. Perhaps the author emphasizes too strongly the importance of antiaircraft gunfire, as he fails to mention the most effective measure for diminishing the accuracy of aircraft bombing. This is a heavy smoke cloud, which, laid by the leading destroyers of a group steaming into the wind will hide the larger vessels from eyes in the air and thus gain valuable time for active work by our own fighting planes.
The essay gives in detail a program that may seem ambitious to those naval officers who have had to cope with the problem of obtaining the “enormous resources of the Navy Department” from governmental dispensers of revenue. They will scarcely accept as negligible their success in obtaining many millions for the installation of deck protection and great numbers of new antiaircraft guns and control apparatus. Moreover, it would seem that not much more can be accomplished to improve the antiaircraft gun defense of the fleet for many years in view of the following prohibition in Part 3, Sec. 1 (d), of the Washington treaty:
“No alterations in side armor, in caliber, number, or general type of mountitig of main armament shall be permitted—” (in retained capital ships and aircraft carriers).
But there is one idea expressed in the essay that calls for vigorous disagreement, and especially so because this idea is the natural reaction of officers who have not carefully studied the problem. I refer to the discussion of the flying-deck cruiser, inaptly called the “hybrid” cruiser. Others have misnamed it “hermaphrodite.” So once was termed “a cheese box on a raft,” the immortal monitor! _
As the author suggests, it is entirely feasible to convert large, fast merchant vessels for use as aircraft carriers. But since their material preparation in peace would contravene Art. XIV of the Washington treaty, many months after the outbreak of war must be consumed in conversion and training before they are fit for service. Therefore the proposal to employ a merchant vessel carrier and a small cruiser in company instead of their equivalent, one flying-deck cruiser, can scarcely be accomplished during the first year after the outbreak of hostilities.
Before discussing the wide field of usefulness of flying-deck cruisers, we should first realize their cost in treaty cruiser tonnage:
(1) Under the London treaty, a maximum of 83,000 tons (say 80,000) may have flying decks.
(2) This will build eight 10,000-ton flying deck cruisers, each carrying about nine 6-inch guns and twenty-four planes.
(3) None of these 80,000 tons can be used in 8-inch cruisers.
(4) A 10,000-ton 6-inch cruiser will mount twelve guns and carry four planes. (Many officers would prefer eleven cruisers carrying nine 6-inch guns and two planes each; such construction, however, would not change the essentials of this comparison.)
(5) Therefore by building eight flying deck cruisers instead of eight 6-inch cruisers:
We lose: twenty-four 6-inch guns.
We gain: one hundred sixty airplanes in the fleet (more than carried by the Lexington and Saratoga). Eight mobile landing fields.
In condemning the flying-deck cruiser the author quoted Mahan’s words:
In the design of the individual ship of war— exclusiveness of purpose—is the secret of great military success.
The italics are mine. It is in considering the purpose of cruisers that many of us are led astray.
Because the cruiser mounts guns, many assume her purpose is fighting. It is true that every naval vessel should be as well armed as possible, since severe opposition may be encountered in accomplishing a mission, and in this respect a flying-deck cruiser with nine 6-inch guns and twenty-four planes, half of which carry heavy bombs, will, I believe, be the superior of even an 8-inch cruiser. Fighting ability is of great importance in cruisers, but their actual purposes are the following:
Escort for convoys Long-range search for raiders Trade destruction Blockade patrol Raiding
Long-range scouting Fleet tactical scouting Distant screening Close screening
Support and denial of destroyer attack.
Fighting is always a possible result of any of these cruiser operations, but only a probable result of the last two. The purpose is one of the above missions; fighting is incidental to its accomplishment. The steady pressure of the fleet may continue for years with only minor actions; on every day of those years cruiser work is important. Does any reader know of an important naval general action decided as a result of the fighting ability of cruisers? Can any reader visualize an important naval war where subsidiary cruiser activities are not essential to the final winning dispositions of the victorious fleet?
For most of these purposes the flying-deck cruiser’s planes will make her far superior to ordinary cruisers, and under nearly all weather conditions give her greater fighting ability.
The flying-deck cruiser is the ideal escort for convoys. Her scouting planes can insure a route being chosen each day that will be clear of casual enemies, while her bombers can engage successfully any hostile surface or submarine vessel except a carrier or similar cruiser and at a distance that will keep the convoy safe.
In an ocean-wide search for enemy raiders, in a patrol to blockade hostile ports, and in operations against enemy trade routes a flying-deck cruiser’s planes will not only extend the radius of vision from fifteen miles to two hundred miles but themselves can halt a suspicious vessel and conduct it to their floating base. While for raids on convoys, advance bases, submarine patrols, and scouting lines nothing could be better except an aircraft carrier, of which we may have such a precious few.
The great advantages possessed by a flying-deck cruiser for distant and tactical scouting are disproportionate to her number of planes, because these can operate over any sea, however rough, while the planes of an ordinary cruiser cannot be launched except when the sea is smooth enough for landing. And yet her landing deck will actually increase the usefulness of other cruisers, whose planes can there find haven in stormy weather. On the other hand, her bombers can attack the vessels of a protective screen, and so allow our cruiser to penetrate areas usually closed to light craft. Attached to a distant screen her fighting power will permit her to displace even battle cruisers, and in a close screen she is at least as good defensively as any 6-inch cruiser.
In low visibility when surprised with planes on deck, the flying-deck cruiser still will have all the power of her nine 6-inch guns; vulnerability from gasoline fires is not so great as is generally supposed and projected improvements in fire fighting apparatus will remove present objections. But gun defense would only be a last resort, even in assisting or resisting destroyers, because the bombing and strafing abilities of her twenty- four planes are especially effective against unarmored vessels.
In rendering two services a flying-deck cruiser will be the equivalent of a small carrier: attack with heavy bombs on capital ships, and providing an additional emergency and servicing landing deck for the airplanes of the battleships, cruisers, and carriers.
At first sight, this new type appears fantastic. However, after continued study and a stern repression of preconceived notions one is convinced here is a vessel that may well be revolutionary in its effect on sea warfare.
But we must admit the sad truth of the Mahan excerpt chosen as the motto of the prize essay. The seaman not only observes that changes in tactics are unduly prolonged after the introduction of changed weapons, but the unfortunate fellow himself resists the change through persistent conservatism!
The changed weapon is the airplane; where are the changed tactics?