Popular Science ( May 1945 )
Target Kite Imitates Plane’s Flight
by Arthur Grahame
The Army and Navy have reached back 3000 years into history for something to improve the shooting eye of their air gunners.
It’s a kite --- one that performs maneuvers no kite ever performed before. When the war is over it is going to be the delight of kids from 7 to 70. A quarter of a million of the kites have already been produced for machine gunners to rip apart, and production is still going on.
This kite will dive, loop, and bank sharply. It will plummet like a stricken airplane hurtling earthward with its engine at full power. It will recover with all the ease of a pilot hauling back on his stick, and race for altitude.
The Navy’s kite --- it was developed by the Navy and then adopted by the Army --- is called the best air-gunnery target in the world. It was perfected by Paul Edward Garber, who probably knows more about kites than anyone else and who might be called the champion kite flyer of five continents.
As curator of aviation at the Smithsonian Institution in Washington DC, he was custodian of the museum’s kite collection, which ranged from weird oriental kites representing gods and demons to the box kite capable of carrying a man aloft, invented by Lawrence Hargrave, of England.
Garber knew that kites, notably a type invented by Alexander Graham bell of telephone fame, had exerted a profound influence on early airplane design. He had studied kite shapes and their flying qualities from information covering a period of 30 centuries.
Shortly after the United States entered the war, Garberm bow a lieutenant commander in the Special Services Division of the Navy’s B ureau of Aeronautics, heard Admiral John H Towers remark that one of the things the Navy needed most was an improved moving target to speed up the training of aircraft gunners.
Garber tucked that remark away in his head. At that time, he was helping with the production of millions of model airplanes needed by the armed services for recognition instruction.
Garber kept thinking about targets. A kite might do. It would be cheap, easy to produce. But if it was stationary in the air it would be an easy mark for even a novice with a gun. What was needed was one that could do aerobics and dodge bullets.
Working in hours mostly stolen from his sleep, and assisted by Lloyd Reichert and Stanley Potter, fellow kite enthusiasts, Garber perfected his target kite in a little less than a year.
He used as a basis for his kite --- which is without a tail --- one with a bowed cross spar developed from a Malay kite half a century ago by an American experimenter, William A. Eddy. Garber was after instability; this kite had it.
When the wind presses against the covering fabric, the lower portion of the kite becomes a sort of vertical keel. The bowed spar becomes a weight carrier similar to that of a bird’s wings. Lateral balance can be destroyed and restored simply by altering the air pressure on one side or the other of the face of the kite. Garber added a fin near the lower end of his upright mast to augment the keel surface. To this he attached a rudder, controlled by the kite’s operators by means of twin flying lines.
When he was satisfied with his product, Garber demonstrated it for Captn Luis de Florez, Chief of the Special Devices Division, who in civilian life is a successful inventor and consulting engineer. Captn de Florex watched the kite’s spectacular aerobatics for a few minutes.
‘That’s fine’, he said, with a cheerful disregard for navy red tape. ‘Get 1500 made up’. Demonstrations to other Navy officers and to the Army were enough. The Garber kite was adopted.
The kite must be good. Gunnery officers are elated when their students hit it once in 50 shots.
What the target kite will do to peacetime kite flying is easily imagined. Appropriately, it is being manufactured for the armed forces by A G Spalding and Bros, makers of athletic equipment.
US Patent # 2,388,478
( Cl. 244-153 )
This invention relates to kites, and in particular to those which can maneuver from the ground, together with devices for their control.
Kites have been used for sport as well as for utilitarian purposes for a great many years. Some have been designed for great lifting power and some have been designed more in regard to their beauty or oddity. Several types of maneuvering kites have been known, among those being types which could be controlled from the ground. Among the latter type are those illustrated in the Patents # 1,744,529 and 1-908,325 to DeHaven.
My invention relates to maneuvering kites of the type which may be controlled from the ground by the operator. The kite and control apparatus is specifically designed to provide a maneuvering target for anti=aircraft target practice, and the kite is rapidly and easily maneuverable, making it particularly useful and successful for that purpose, however it is also suitable for signaling purposes or the like and for sport.
While the aforementioned patents to DeHaven disclose kites having some degree of maneuverability, there are differences in structure and control mechanism in my device which provide a much more speedy and maneuverable target. With my apparatus, the kite can be made to describe loops, vertical or horizontal figure 8s, steep dives and climbs, ordinary turns, and combinations of these maneuvers. The operator may stand in one place on the ground if there is sufficient wind to fly the kite, or he may ride a vehicle or other moving platform in order to provide relative wind to fly the kite or in order to tow the target past a long line of guns while maneuvering it. The simplicity, positiveness, and ease of operation of the control means makes it possible to operate the kite from such a moving platform.
It is, accordingly, the major object of my invention to provide a maneuvering aerial target apparatus for anti-aircraft gun practice wherein a maneuvering kite and controls therefore, operated on the ground, cooperate to furnish a rapidly and completely maneuverable aerial target.
Another object of my invention is to provide an improved apparatus for controlling a maneuvering kite from the ground by the kite strings.
It is another object of my invention to provide an improved apparatus for controlling a maneuvering kite from the ground by the kite strings.
It is another object of my invention to provide an improved apparatus for controlling a maneuvering kite from the ground by the kite strings.
Other objects will become apparent as the description proceeds in connection with the attached drawings, wherein:
Figure 1 is a perspective view of the kite in operation and showing the operator using the reel to control the kite.
Figure 2 is an enlarged perspective view of the kite of Figure 1.
Figure 3 is a plan view of the reel shown in Figure 1.
Figure 4 is a side elevation of the reel shown in Figure 1.
Figure 5 is a partial sectional view along the line 5-5 of Figure 3, looking in the direction of the arrows.
Figure 6 is a partial sectional view along the line 6-6 of Figure 5, looking in the direction of the arrows.
Figure 7 is a back or top view of the kite.
Figure 8 is a partial sectional view showing details of the fin and rudder and the method of attaching them to the mast of the kite.
Figure 9 is a view if the structure shown in Figure 8, as seen when viewed from the left of Figure 8.
Figure 1 shows the kite 1 in flight under the control of an operator on the ground. The kite is a two-stick, diamond-shaped Eddy pattern type. Operation is by means of two lines 2 and 3 which extend up to the kite from the ends of a control bar 5 held horizontally by the operator. The control bar is of substantial length so that by moving one of its ends towards or away from the kite a relatively large movement of the line 2 or 3 will occur. A length of 4 feet for the control bar has been found to be effective, bit this figure is not intended by way of limitation. A reel apparatus, shown best in Figures 3 to 6 is combined with this bar for most effective operation.
Near the kite, the lines 2 and 3 are connected to the opposite ends of a horizontal bridle sick 6 as shown best in Figure 2. Control cords 8 and 9 extend from the bridle stick, passing through a pair of screw eyes 10 and 11 and thence to the ends of a tiller bar 12 on a rudder 13 which is pivoted about an axis substantially perpendicular to the mast 17 (Figures 7-9) of the kite. The screw eyes 10 and 11 are screwed through the kite covering 18 into the bottom of the spar 19 (Figure 7), at equal distances from the mast 17, the total distance between the eyes being substantially equal to the length of the bridle stick 6.
A bridle line 20 is fastened at its end to screw eyes 21 and 22 which pass through the cover 18 and screw into the bottom of the mast as shown clearly in Figure 2. With a kite having a mast 17 which is 5 feet 1 inch long the spar 19 is bolted thereto at a distance of 9 inches from the forward or top end of the mast. The screw eye 21 is located 4-1/2 inches on either side of the mast since the bridle stick is 12 inches long. The bridle line 20 is 80 inches long, and fastened at each end to the screw eye 21 and 22. At a point 23, which is 30 inches from where the bridle line is fastened to screw eye 21, it is fastened to a screw eye at the mid-point of the bridle stick as shown in Figure 2. The length of the bridle line 20, the positions of the eyes 21 and 22, and the position of the point 23 are important because they determine the angle of attack of the kite.
Since the lines 2 and 3 are fastened to the ends of the bridle stick and the bridle line 20 is fastened to the middle of the stick, the tension or pull in the bridle line 20 when the kite is flying is evenly distributed to the two lines 2 and 3. The control cords 8 and 9 are not intended to take any of the tension in the lines 2 and 3 under most conditions, and for that reason when the bridle line 20 is under normal tension the control cords 8 and 9 are adjusted with a little slack.
Details of the rudder 13 and vertical fin 25 to which it is attached are shown in Figures 8 and 9. The vertical fin has a portion 26 which extends through a slot in the mast 17, being fixed therein by a bolt 27 which passes through the portion 26 and the mast.
The rudder 13 is hinged to the rear of the fin 25 by means of a pintle 27 which passes through hinge straps 28 and 29 fastened to the fin and rudder respectively. The tiller bar 12 is suitable fastened to the rudder near the leading edge, projecting from each side of the rudder a substantial distance; in the case of a kite of the dimensions given above, the tiller bar will have a length of 5 inches from end to end. The rudder can be moved through an angle of approximately 90 degrees to either side of its midposition, whereupon it strikes the side of the vertical fin which provides a stop.
The cover may be applied to the kite in any convenient manner. In the embodiment shown the ends of the mast 17 and spar 19 are slotted to receive a boltrope 30 which passes loosely within a hem in the periphery of the cover. At the corners the boltrope is exposed so that it will slip into the aforementioned slots. The boltrope is tensioned by drawing its two free ends through the slot in the forward part of the mast and then fastening them in any suitable manner, as by clamping them under a washer and wingnut 3.
The spar is bowed by tightening the bowing line 32 (Figure 7) which is attached to its ends. The amount of bow is determined by the strength of the wind in which the kite is flown.
In view of the fact that the cords 2, 3, 8, 9, 20 and 32 change in length with weather conditions, age, tension, etc., means should be incorporated in their connections to the kite whereby their length can be easily adjusted.
As indicated in Figure 2 the outline of an airplane is painted n the cover of the kite. Preferably the outline is in black and the rest of the cover is the same color as the sky, by which device the airplane outline makes a more realistic target for anti-aircraft target practice.
While the kite may be controlled with a plain stick for the control bar 5 shown, it is much more convenient to use the combination control bar and reel apparatus to be described below. If a plain stick is used it should be about 4 feet long and the lines 2 and 3 tied to its opposite ends. It will be understood that by manipulating the stick to pull line 2 or 3 towards the operator the rudder 12 is shifted to make the kite turn one way or the other.
The control bar 5 and reel shown generally in Figure 1 is shown in enlarged detail in Figures 3 to 6. Two wooden sticks 34 and 35 of equal length are fastened together in parallel but spaced alignment, there being separators 36, 37, and 38 at their ends and at their mid-point. Intermediate separators 39 and 40, have passages therethrough to permit the lines 2 and 3 to pass through them and whereby these separators also act as guides.
Adjacent each end, between the sticks 34 and 35 are pairs of spaced pulleys 48 and 49. The lines 2 and 3 pass between the pulleys 41, 42, and 45, 46 and into the space between the sticks 34, 35, thence to the pulleys 48 and 49, and thence to the reels 51 and 52, as shown in Figure 3.
The reels are mounted on a shaft 53 which is journalled in the sides 55 and 56 of a frame 57 which is attached to the control bar at its midpoint, straddling the pulley 48 and 49. Each pulley if fixed to an outer shell 58 of a free-wheeling clutch, the shell being rotatably journalled on the shaft 53. Within each shell is a clutch hub 59 having wedge shaped pockets in its periphery, each pocket containing a roller 60. Each clutch hub is fixed to the shaft 53, and when the shaft is rotated clockwise as viewed in Figure 6 it will rotate the reel 51 clockwise. Reel 52 will be simultaneously rotated by its clutch, as will be understood. The two reels 51 and 52 are slightly spaced by separating washers 61. A crank having a handle 63 is fixed to the end of shaft 53. A strap 62, which is fastened to the top of the control bar 5, may be slipped over the handle 63 to hold it when desired.
Brake drums 64 and 65 are fixed to the shaft 53, one on each side of the pair of reels. A brake yoke having side arms 37 and 38 and a connecting handle 69, is mounted for pivotal movement with handle 69, is mounted for pivotal movement with respect to the reel frame 57 by means of the hinged mountings 70 and 71 which are fastened to the frame sides 55 and 56. At their rear ends the brake yoke side arms 67 and 68 are provided with brake linings 72 and 73 which are curved to fit the surface of the brake drums. When the brake handle 69 is raised by the operator the brake linings 72 and 73 which are curved to fit the surface of the brake drums. When the brake handle 69 is raised by the operator the brake linings 72 and 73 will be simultaneously pressed against the drums to stop the rotation of the shaft 53. As the brake is used to stop rotation of the reels when paying out the lines 2 and 3, during which time the reels are rotating counter-clockwise as viewed in Figure 6, it will be apparent that stopping the shaft 53 by the brake will stop the reels due to the wedging action of the rollers 60.
The frame sides 55 and 56 are joined at their rear end portions by an end wall 74 to which is fastened a hook 75 adapted to be hooked behind the belt of the operator. At their forward end the sides 55 and 56 are fastened at their bottom to the control bar 5, there being a connecting brace 76 connecting their forward and upper portions. Screw eyes 77 and 78, fastened to the frame sides at their forward and upper end, provide fastenings to which are attached the ends of a shoulder harness 78 which passes over the shoulders of the operator. By means of the hook 75 and the shoulder harness 79 the whole reel and control bar are suspended on the front of the operator and his hands are free to manipulate the reels, brake, crank handle, and the control bar 5. Normally, the operator can rest his right hand on the crank handle, and his left hand on the brace 76 at the front of the frame 57. He can easily reach the fingers of his left hand down to grasp the brake handle 69 to that he can raise the handle to apply the brake. The brake is useful not only in slowing the running out of the flying lines as the kite ascends, but can be often used to hold the lines taut to test their evenness while wither drum is being compensated to take up slack in the lines 2 or 3. The brake should always be used to arrest the revolving reels after paying out line. Grabbing of the rotating handle for that purpose pits a strain on the reel and kite.
The necessity for the differential action of the two reels becomes apparent when the kite is flown. Then it is seen that although the reel is designed with narrow drums, and some lateral play while cranking, so that the incoming and outgoing lines will shuttle back and forth to avoid piling up on one side or the other of the reels, even so, there will be unevenness, often too great to be compensated by yawing the control bar 5. Moreover, the yawing action should be used only for maneuvering of the kite by moving the bridle stick and consequently the rudder. Therefore when the kite is being flown the length of the lines 2 and 3 should be adjusted by manipulating the individual reels 51 and 52 until the lines 2 and 3 are of the same length, with the bridle stick 6 and the control bar 5 both parallel to the kite.
There are two methods of using the free wheeling clutches to adjust the length of the lines. First: If the crank handle 63 has been secured in the crank handle strap 62, push forward on the top of the winding drum of whichever line is slack. Second: If the crank handle is being held in the hand, use the other hand to hold the drum of the line that is slack, and back off on the handle for a portion of a turn, then free the drum and wind both with a forward motion of the crank.
In flying the kite, as mentioned above, a yawing motion of the control bar 5 causes a yawing of the rudder. The relative proportions of the control bar 5, the bridle stick 6 and the tiller bar 12 are therefore important because with the elongated control bar a relatively small yawing motion thereof results in a much larger or magnified motion of the bridle stick.
One of the additional advantages of the control mechanism used with the described kite is an effect which results when the control bar 5 has been yawed to such an extent that the rudder 13 has moved to an extreme position, where it is stopped by the engagement of the tiller bar with the vertical fin 25. When this occurs, the control cord 8 or 9, as the case may be, is placed under tension. Since the screw eyes 10 and 11 are spaced a distance from the mast it will be seen that the application of the above described tension to the cord 8 or 9 will apply a force to the kite to the side of the mast and on the same side thereof as that towards which the rudder is turned. The direction of this force is such as to incline the kite surface toward the direction of pull so that it reacts like the sail of a boat.
The form of kite shown is inherently stable. The wind pressing the fabric of the cover on each side of the mast forms the cover along that line into a vertical keel. The vertical fin 25 augments this keel surface and, being at the bottom, adds to the steadiness. The addition of the rudder provides a means of variable pressure against the air stream flowing along the keel and steer the kite. The recover of the kite from each maneuver is facilitated by its stableness and its natural tendency to climb. It is to be understood that the specific dimensions for the kite, as given in the preceding part of the description, are by way of example only, and are not meant as limitations.
It will be understood that the above description and accompanying drawings comprehend only the general and preferred embodiment of the invention and that various changes in details of the construction, proportion and arrangement of parts may be made within the scope of the appended claims and without sacrificing any of the advantages of the inventions.
[ Claims not included here ]