25 September 19455. Prototype completed:
Development engineering: The first tests conducted by the project engineer in maneuvering experimental controllable kites by means of two lines were made with a simple reel much like that illustrated in the drawing, Supplement #1. This sufficed for letting out and winding in the lines but it lacked any means for braking, steering or adjusting. In the experiments made by Mr. Lloyd Reichard, the civilian kite enthusiast who worked on this idea in 1942 and whose contributions are detailed in Device Jacket 3C-29, he used separate reels, each handled by a separate operator, but much of his kites' erraticism could be traced to lack of coordination between the two handlers. When the project engineer resumed tests late in 1942, with the assistance of Mr. Stanley Potter, civilian assistant on contract, simple box reel, illustrated in Supplement #2 was first used. Although the two flying lines were wound together they were divided at their egress by a vertical wire, and a strap brake served to slow down the run-out of the kite. This was but a temporary utility and a special reel was made to incorporate the requirements of this unique kite.
The photograph, Supplement #3, shows its several advantages over the simple reels. The lines instead of being on one spool were divided on a spoked drum turned by a crank. This winding assembly was turned by a crank and surrounded by a frame which provided bearings for the crank; metal strap-angles were screwed to the rear (bottom in photo) for hanging the reel on the operator's belt and screweyes at the front were connected by straps to the operator's shoulders for supporting the reel at a proper angle. The let-out of the lines was controlled by a brake, the arm of which appears at the left-inside of the frame. This was pulled up by the fingers of the left hand; it had a hinged fulcrum near the center of the frame-side and its lower end bore on the hub of the winding assembly to effect a braking pressure. The lines went forward from the drum to central pulleys at the front of the frame and thence outward to pulleys at the end of the spreader bar, then forward to the kite. This bar separated the lines and gave a wider leverage when controlling the kite.
This reel didn't carry enough line, so a second one was constructed with larger drums, using drum-discs instead of spoke separations. Minor structural changes were made but the principal features of the previous reel, including supporting angles and screweyes, brake, and spreader bar were retained, as shown in Supplement #4. The larger central discs of the winding drums provided quicker winding of the lines (more line handled per rotation of the crank) and enabled the kite to fly at a more realistic range, -- about 200 yards.
It should be understood that the quality of the line is an important factor in handling controllable kites at long range. It was learned that cotton line, even when strong enough, was liable to stretch as much as a yard or even more in the 200 yard length so that a pull of either line to maneuver the kite was largely dissipated by the stretch and the kite would not respond in accord with the amount of control given. Moreover, the other line would stretch as the one line was pulled, and permit the kite to turn over further than the operator intended. In addition, the large diameter of cotton line which corresponded to the required tensile strengths presented a windage drag which caused the lines to sag and required additional pull to overcome. Nylon lines were tried and although the greater tensile strength permitted a reduction in diameter, there was even a greater stretch than cotton, and therefore unsuitable. Linen was found to be the best. An 11 ply line has strength of 70 pounds for a diameter of less than 1/16 inch and the stretch is not apparent. The linen line as supplied for wing airplane fabric is satisfactory in every way, and readily available, being kept in most Navy supply houses.
25 September 19455, continued,
The experiments with longer lines brought out an additional factor, namely that as the lines fed out or were wound on to their drums, each would vary in length according to the manner in which they would be reeled. The lines would feed from side to side of their drums, at one time piling to a high side, or at other times filling in a low side. These differences in circumference would vary the amount of line fed per revolution, and because these would be different drum for drum, the length of lines extended would become different. With a short extension of lines the differences could be absorbed by swinging the spreader bar, but with longer lines the variation would become more than the arc of the bar-swing could compensate for. Moreover, if the bar became out of parallelism with the bridle stick of the kite, the control of the kite would be awkward because the pivoting of the bar would be off center.
Another condition served to accentuate the need for some method of adjusting the lengths of each line. The two reels illustrated in Supplements 3 and 4 were used for the test of the kite under fire at Dam Neck, Va., 22023 January 1943, described in Device Jacket 3C-29. The two lines of each reel had been made of equal lengths so that when fully extended the bar and bridle stick would be parallel, - the preferred condition for best control. However, during the course of firing, bullets would shorten that line, putting the bar and stick out of parallel. Thus it was realized that under actual service there should be some means, readily available to the operator, of making the lines even without having to measure and cut the lines at their outer ends, obviously an awkward and impractical method.
Supplement #5 shows the next reel constructed, which incorporated a line-adjusting feature. Whereas in the previous reels the two drums of each reel had been integral with the shaft, in this reel the drums were separate. The hub, for the space occupied by the drums, was square. The left hand drum was secured to the hub, but the right hand one was free to slide laterally to the right. While on the squared section, snug to the other drum, both rotated together, but when any inequality in the lines was observed, the right hand drum could be slid off of the squared section on to a round section by means of the operator's left hand, which held this drum secure while his right hand rotated the crank forward or backward as required to lengthen or shorten the line from the left hand drum and thus make the lines equal. This worked rather well, but the tension in the lines caused by the pull of the kite made it somewhat difficult to slide the drum on and off. Two other improvements were added in this reel, namely the addition of an outer pulley in the spreader bar which eliminated the friction of the line against the end spacer; and a loop of strap metal in the right hand arm of the bar which could be swung inward to hold the crank-handle after the kite had been let out to range and the lines adjusted evenly. Whereas the two previous reels had been "home-made" by Mr. Potter, this squared-hub reel was made in the Special Devices Shop, plus a number of copies which were sent out in answer to requests for kite equipment before the Comet-manufactured reels were available.
At this stage of development, the project engineer and his assistant were working also on the construction of several large kites, 7 feet, and 10 feet in size, in accord with the suggestion of Lt. Comdr. Gardner who had shown much interest in the demonstration under fire at Dam Neck, Va.. It was foreseen that these would have more pull than an operator could hold unassisted. A power reel was therefore constructed, and bolted to the back of the jeep, which, with its brake on, provided a good anchor, against the strongest pull to be expected. The main unit of this reel was a lawnmower, chosen because the outer surfaces of its two wheels provided
Betty- ? - Lawnmower, one word or two or hyphenated?
26 September 19455, continued,
A foot-operated brake was provided
a surface for attaching each drum, its cutter-shaft provided a geared-down ratio for the drive pulley, and the ratchet mechanism could be used for adjusting the lines evenly. In order to control the kite by pulling either flying line, levers were arranged behind each drum and each line ran through a pulley system so that the movement of each lever would be augmented. It was foreseen that the pull of the kite would run the lines out. For pulling them in an electric motor was used, this being a Ford starter motor energised by the jeep's battery and controlled by a switch, pressed by the operator's foot. The same pressure contacted the switch and tightened the belt. Thus when the switch was not closed the belt was loose and permitted free running out of the lines. This device is illustrated in photograph Supplements 6, 7 & 8. It was used at Dam Neck, Va., for the tests of the large kites under fire and functioned very well. Following the decision of the Director to concentrate on the five foot kites, this reel was set aside for experimental use only, but in addition to its own good qualities and the experience gained in its use, it contributed one very useful item to the hand reels, namely the lawn mower ratchet.
Lawn mowers employ ratchets which engage when during a forward push and ride free when the mower is backed up. They also operate with a differential action as the mower is steered. They may be of either a sliding pin, sliding flat pawl, or roller type. The decision to incorporate the ratchet in the hubs of the hand reel was a definite advance. The first reel in which it was used is shown in Supplement #9. It functioned excellently from the very beginning, and the method of operation, -- to hold with the left hand the drum whose line is too long, and back up the handle with the right hand to let out the shorter line to even length, -- becomes instinctive after short practice. The photograph shows an additional improvement and also a modification. The improvement was the two-lever brake yoke which doubled the pressure and reduced the manual effort. This idea was contributed by the contractor, -- the Comet Model Airplane & Supply Co., of Chicago, with whom the manufacturer was by this time being discussed. They, and the other contractors showed a very cooperative attitude throughout all of the negotiations for Target Kite equipment. The modification illustrated was the double crank. This was a good idea, enabling the pull-in of kites with less effort, but it was not carried into the production reel because it was not absolutely necessary, adds weight to a reel already quite heavy, and is liable, when the kite is running out rapidly, to knock the left arm of the operator. (Present opinion of the project engineer, however, is that could be added to future production, and despite the disadvantages listed, its advantage offset its weight and hazard.)
The development engineering on the reel was completed by the middle of June, 1943.