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8 October 1945

Device number, name, and classification:

3 C - 2 9 1.





  Not classified.

8 October 1945

2. Request for authorization:

  Herewith as Supplement #1.

3. Approval:

  Endorsed on original of Supplement #1.

4. Assignment of Project Engineer in cognizant section.

  Official approval of Lt. Comdr. Garber endorsed on Supplement #1.

5. Prototype completed:

Supplement #1 recounts the reason for originating this project, namely, to provide a device of controlling the kite which would weigh less and have fewer parts than the Mark 1 reel. The first reel came into being by starting with a simple winder, and adding parts as each additional feature was found to be required. The final form embraced all of the requirements but was rather heavy. This weight was distributed to the operator's body by the harness but nevertheless the reel is cumbersome. In the interests of getting into production the design was frozen, but later, the Project Engineer returned to the basic problem, and this time started with the fundamentals, which are:

  1. A means for winding and unwinding the lines.
  2. A means for slowing down and stopping the kite when let out of range
  3. A means for evening the lines at any range.
  4. A means for spreading the lines to facilitate control.
  5. A means for supporting the weight of the assembly.

  1. If we start with the premise that the simplest reel should be gradually operated, the obvious means for rotating the reel would be by a hand crank. Experience with the box-frame reel (Mark 1) showed that if both hands could be used the effort was easier. Therefore a double crank-arm become a fundamental method for rotation.
  2. The brake should be applied by some means of bearing on the rotating member. Experience with the simple drum bar, described in the 2nd edition Manual, Page 16, had taught that the pressure of squeezing the hands on the bar was usually enough to slow down the rotation, but the effort of squeezing made the hands hot, therefore a shoe to insulate the hand and distribute the breaking pressure becomes an improvement over the simple hand grip. The obvious point for the letting out of lines to terminate is when the kite is at its effective range, about 250 yards and the simplest means of attaining that range is to provide lines of that length and run them all the way out. To prevent a terminating jerk on the end of the lines which might break the root connection, a simple indicator would be a ribbon tied about 50 feet from the root and which, as it ran out would inform the operator that he should apply the brake to reduce the final jerk, which could be

    8 October 1945

  3. The lines become uneven as they pay out from either the high or the low side of their respective drums. This is unavoidable on a random-wound drum. The easiest method of making the lines more even is to lengthen the tighter line, rather than trying to shorten the looser one. It was found with the simple drum bar that adjustments could be made by simply using the hand to pay off an extra turn of the lines from the drum on the tight side. This could not be done if the drums were enclosed in a frame. but was feasible if they were exposed.
  4. The simplest way to spread the lines is to have the drums themselves at the ends of an extended shaft.
  5. If the assembly could be made light enough the need for support was minimised, and the reel could be hand held, or, if necessary, hung on a simple strap harness, of loop-fitting on the operator's belt.

The photograph, Supplement #2 shows how these fundamentals were incorporated into a crank bar reel, in which function (a) is accomplished by letting the pull of the kite unwind the lines, and the rotation of the hands on the double crank can reel them in; (b) the brake is a squeezing action over a rubber hose grip at the ends of the bar; (c) lines are evened by a movement of either hand to unreel an extra turn; (d) lines are spread by separating the drums about 3 feet apart which was proven with the Mark 1 reel to be a practical division; (e) the reel was intended to be light enough to obviate the need for any harness.

6. Delivery of prototype for test:

The reel as pictured was made in the Special Services Division shop, and delivered to the Project Engineer 8 March 1945.

7. Report of test of prototype:

Two lengths of flying line were measured evenly to a range of 200 yards, and wound on the crank bar reel. In the test with the kite, our faults were disclosed: (1) The reel was so heavy as to tire the operator. It had been made of steel tubing in an endeavor to secure strength with lightness but the wall-thickness of the tube embodied more weight than expected. Gross weight, (including 4/5 pounds of line) 8½ pounds. (2) When winding in the line they would occasionally get off the drums and coil about the bar. (3) Hand pressure was inadequate to slow down the kite in a strong wind, and (4) the sudden jerk as the lines were let out to the limit and the tension came abruptly on the knot on the drum, broke the lines so that the kite veered off out of control.

After this test the project was set aside during the instruction of a class of students, who were taught with the standard equipment, but when opportunity permitted another reel of the crank bar type was requisitioned, to incorporate the following

8 October 1945

improvements; numbered to conform to the previous listing of faults:

  1. Lighter construction. Substituting ½" bar for 1" tube, and using wood for the handle and brake hubs.
  2. Adding a line guide to direct the lines onto the drums. It was believed this would facilitate the act of adjusting lines in that this guide might be flipped around to extend the shorter line.
  3. Increasing the diameter of the brake hub and substituting wood for metal; slippage could be reduced by applying resin to the hub.
  4. Instead of fastening the root of the line with a slip knot around the drum, an eye bolt was to be screwed to the flange of the drum, and the line tied thereto by a four-strand "fisherman's bend", which is a superior knot for this kind of connection. In addition, fifty feet from the root a short (10") length of red ribbon was to be tied into the flying line from the right drum, so this, as it paid out, would indicate to the operator that the end of the line was near, and he should brake down to a stop and pay out slowly until the end was reached.

8. Approval of quantity for production:

At the time of devising this reel the supply of Mark 1 reels was adequate to fill existing requests, and it was preferred to use up that supply instead of offering substitutions. To date of writing this device jacket this same condition prevails, but it is hoped to bring this reel to such state that all faults will be eliminated.

9. Memorandum on negotiation of contracts.

  No contracts processed.

10. Copy of procurement directive.

  No contracts processed.

11. Photograph of production models

Upon completion of the model incorporating the corrections outlined in section 7, its photograph will be added to this report as Supplement #3.

12. If the corrected crank-bar reel fulfills its purpose a training bulletin or manual insert will be written to describe its operation and maintenance.