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History of Compound Bows
The Compound Bow
Twenty-five years after Allen's patent of December 1969.
by W.E. Flewett
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This article was first published in the Journal of the Society of Archer-Antiquaries, volume 37, 1994.
Reproduced with permission. Please read the copyright notice.
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'Here was I, preparing to unfold the pageant of the past, and the present quietly put it's hand through the printed page of history and said: - 'it is here, it is now'. (Prof. J. Bronowski)
The scene is a plain in Mesopotamia 4500 years ago - a line of archers clad in homespun, woven from the hair of their goats, holding wooden self bows; they are gazing with astonished resentment at a newcomer whose arrow, loosed from a strange-looking bow with angled limbs, has just swept far past their shafts on the field of flight.
`Do you think he's a sorcerer? -There must be a demon in that bow!`-
'I did hear him tell the chief that his bow contained horns from an Ibex and tendon from a bull '...
Well, I think his bow - if you could call it a bow- is disgusting, an ugly monstrosity, - but what else could you expect from a Sumerian?'
How fascinating it would be, if we could travel back in time and observe at first hand, episodes such as this in the history of the bow, noting as the centuries slipped by how, despite initial opposition, the 'ugly monstrosity' with recurved limbs, rigid 'siyah' and composite construction became acknowledged as effective in hunting, deadly in war, eventually even being recognised as a thing of beauty, decorated and proudly signed by the makers, whose advertisements might truthfully have claimed:- 'As used by the Sultan himself!'
But wait! Substitute 'Compound' for 'composite' and 'American' for 'Sumerian', and some of us, even in this present decade, have heard muttered comments remarkably like those of our imaginary scene of ancient times!
In 1967, after six years development in the garage of its inventor in Missouri, a strange looking device, described as a 'compound' bow was born. Many a new-born infant appears unattractive - except, of course, to its mother!- And a photograph showed this to be no exception.
Twenty-five years have gone by, and this extraordinary bow is now of age, and despite the serious drawback (to the antiquarian) that it has not yet had a chance to grow old, it would be a pity not to avail ourselves of the opportunity to look at the development of this most interesting weapon, while appreciating our good fortune that its evolution is still continuing.
Archers have always cherished their traditions ever resistant to and (rightly) wary of changes threatening to disrupt the nature of their ancient sport. Some of us recall the appearance on the target line of steel bows. Though their Indian ancestors look magnificent in a museum of oriental weapons, the modern equivalents (made by the makers of golf-club shafts: need one say more?) were not exactly welcomed by all.
In the late 1930's, after the war, and even as late as 1960, despite the interest in new 'gadgets' by the average American, recurved bows of composite construction were still regarded with doubtful suspicion by bow-hunters in America, notably the physically powerful and supremely skilful Howard Hill. However few bowhunters had as good a physique as he, and even with the latest composite recurve, many archers lacked the capability to send a heavy broadhead arrow on its way with sufficient speed to ensure a clean kill of a wary deer. (In Olympic years we have seen how quickly a human can react to a starting pistol.) In 1960, bowhunters were complaining that, even at a range of only twenty yards a deer could react so quickly to the twang of bow string that the arrow missed or -much worse- only wounded.
When the need arises, and the technology is available, it often happens (as with the motor car) that several individuals become interested quite independently of each other in trying to improve or develop a machine or weapon. This was probably the case in various parts of Asia four or five thousand years ago, when a recipe for a good fish glue might perhaps have been the technology needed to initiate experiments by bowyers in different tribes.
So it was in the USA, in the early 1960's, an enormous surge of interest in bowhunting creating the need, modern glues and fibreglass the technology. With a multitude of bowhunters, many of whom were engineers, it was perhaps inevitable that a number of them would experiment with devices to improve the efficiency of the bow.
One such was a keen bowhunter, Holless Wilbur Allen: he was also a very able mechanic.
Early in 1961, at his home in Missouri, he would have been excited at the unveiling, by the nearby Hoyt Archer Company, of the 'Pro-Medalist', the first bow to be fitted with torque stabilisers (an innovation which was to have as profound an effect on the appearance of the target bow as the invention of television to the outline of chimneys of the family home).
Perhaps stimulated by the new Hoyt bow, and with vague memories of school blackboard chalk drawings such as this:-
Wilbur Allen had an idea: what about attaching a pulley to each bow limb, to create a block-and-tackle effect? Using limbs sawn off a recurve bow and ordinary pulleys with a central axle, he built an experimental bow; but, disappointingly, the draw length was very limited owing to the short distance travelled by the limb tips.
However, during a further four years' experiments, he tried cam-shaped pulleys, and also circular pulleys with the axle off centre ('eccentrics') and found that as the string unwound, a draw length sufficient for normal length arrows was obtained. But also, there was an astonishing bonus! The draw weight reached it's maximum half-way through the draw, with a much reduced pull required to hold the string at full draw! This was exciting, but even more so was the astonishing cast of the new bow !
From January to June, 1966, he refined his design, and on June 23rd. 1966 he filed an application for a U.S. patent. It was accepted, and eventually granted in December 1969. Several other archers had been experimenting with similar devices, but apparently with less advanced results: The patent application was for 'An archery bow with drawforce multiplying attachment'. It should be said that the two sheets of drawings showed a bow that was to all intents and purposes an 'archery bow', but with the bow limbs attached to the handle riser with adjustable bolts. The bow limbs were also unusually thick, and each had a V-shaped slot at the tip. So, what were the 'attachments'?
Two alternatives were shown on the patent drawings: a cam-shaped pulley was featured on the bow which appeared on both sheets, fixed in the V-shaped slot at each limb-tip, the second sheet depicting the cam at various stages of the draw; but also on the second sheet was a detailed drawing of an eccentric wheel as an alternative to the cam. The sectional drawings showed both cam and eccentric wheels to be quite narrow. The string was led around the cam or eccentric, to be attached to the opposite wheel axle, therefore three times as long as an ordinary string.
Very few innovation are met with immediate enthusiasm, and at first, it seemed that Wilbur Allen's years of work had been wasted: when he tried to find a manufacturer for his new bow, nobody was interested; so he decided to 'go it alone', and make the bows himself. The eccentric wheels of his original patent were more stable than the cams, so were chosen for the early production bow, but the crossing strings or cables near the centre line of the bow tended to be struck by the advancing arrow, so the 1967 model was modified by the addition of 'idler' wheels attached near the middle of each bow limb; these wheels had the advantage of leading the crossing cables a little to one side of the centre line of the bow, thus avoiding arrow-cable collisions.
At first, there was some sporadic interest from one or two astute individuals who recognised the bow's potential, but of officially, nobody wanted them: "ugly", "mechanical", "a monstrosity" were a few of the epithets used. Though in essence this was a bow which was held, drawn, and released like any other, it certainly looked odd. American State laws banned the use of "Mechanical Devices" for bow-hunting, and the rules of the Archery associations were likewise prohibitive of its use for target and field shooting.
However, Wilbur Allen sent a sample bow to Tom Jennings, the technical editor of 'Archery World' magazine (and also a bow-hunter himself). Jennings field-tested the new bow, using a 'trajectocaster' to eliminate human error, and published the results in the May 1967 edition of 'Archery World', using the name by which the bow would always be known:
BOW WITH COMPOUND INTEREST
Summarised below are the results of the tests:
Allen's claims :
50% increased speed.
The bow reaches its peak draw weight at and relaxes at full draw to 15% less than peak draw weight.
5% to 10% lighter arrows can be used.
Jenning's results
Compound reaches its peak at 22ins., and lets of 121bs. at full draw.
This is the first bow i have ever tested that actually lets down in the latter stages of the draw . I believe this is the most important feature of the bow.
Bow is more stable than ordinary recurve.
Bow will handle arrows of much lighter weight than equivalent recurve.
The bow was also given its 'baptism' when Jennings allowed over 100 archers to try it on a Field course. Every single archer was highly impressed with the speed and performance of the compound bow.
The sequel to this was that Jennings took out a licence under the Allen patent, gave up making recurves, and concentrated solely on producing compound bows. Subsequent events proved him right, but it was years before the bans by State licensing authorities and Archery associations were lifted. Both Allen and Jennings worked hard to this end, trying to persuade the 'powers that be' that there was nothing basically unethical about the bow, and throughout the United States individual archers who had tried the bow brought pressure to bear on the authorities to change the rules.
Meanwhile, there was nothing to prevent the owners of compound bows bringing them along to flight shooting competitions, where they were greeted with interest, and allowed to compete in the bow hunting division.
For propelling a broadhead arrow, no other bow could touch them, and, in the autumn of 1967, standard Jennings 'compound' bows swept the 65lb. and unlimited divisions in the National (Bowhunters) Flight shoot.
Advertisements soon began appearing in Archery magazines:- "Do you want 50% more speed, super accuracy, and relaxation at full draw?" (Allen, in 'Bow and Arrow' 1968).
"The JENNINGS compound bow is the first really new concept in a bow in 2000 years" ('Archery World' May 1969: this seems a bit unfair, as the said bow was a replica of the Allen design!)
Meanwhile, on the previous page of 'Archery World ', the Hoyt Archery Company were advertising: 'New Torque Flight Compensators'.
By 1970, only one or two other manufacturers apart from Jennings were starting to build what were virtually Allen bows under the Allen licence, but in February of that year, the compound bow was ruled to be legal for National Field archery competitions and bow hunting awards. By 1974, eight firms had begun competing for the now rapidly expanding compound bow market.
Bowhunters all over the United States had come to realise that a bow was now available with a maximum peak draw weight of 60 or 70lbs. which could be held comfortably at a full draw weight of 35 to 40 lbs. Archers of average strength could loose a broadhead arrow with sufficient velocity to ensure, in the event of a hit, adequate penetration of a big-game animal such as a deer.
A survey, by Allen Archery, of experienced bowhunters showed the recovery rate of big game hit using compounds to be substantially higher than with recurves.
(It might be mentioned here that probably the majority of archers in the U.K. view bowhunting with distaste, irrespective of the fact that it is illegal in this country to shoot deer with an arrow. Nevertheless a survey carried out in Pennsylvania in 1975 showed nearly 25% of hunters used a bow, yet they took only 3% of the number of deer taken by gun hunters. On these figures, even allowing for some wounding, were there two equivalent deer forests allocated respectively to bowhunters and gun-hunters, the prudent deer might display better judgment if he chose to take his chance with the former. In this connection, the Missouri Department of Conservation, in collaboration with the family of the late Wilbur Allen, in 1988 established the Wilbur Allen Memorial Wildlife Area, a 380 acre semi-forested tract near Hartville, to provide a deer reserve where only bowhunters are permitted.)
By 1976, the compound bow was legal in every state except Georgia, and 18 companies were producing 39 different models. They could be classified into three groups:
1. Tip-to-tip cable system, with only two pulleys.
2. Limb-to-handle cable system, with four or six pulleys. Some of these, notably the aptly named 'Cable bow' made by the Robin Hood Archery Co., had a bewildering array of strings and cables resembling a 'cats' cradle' of our childhood days.
3. The Martin 'Kam-Act'.
The last-named was introduced in 1974 under a separate patent application by the Martin Archery Co. of Washington. Described as having been under development for 12 years, ( i.e. since 1962) a heavy bowshaped rigid frame entirely of metal had a system of cams in the ends around which the string was led, emerging at right angles to the tips of a pair of powerful laminated bow limbs. This odd-looking contraption, more like a 'siege engine' than bow, was heavy, around six pounds; and possibly because of this and its bizarre appearance, it doesn't seem to have survived the process of evolution.
By 1977 an even more unusual bow had appeared on the American market. John H. Graham II had founded "Graham's Custom Bows" in 1969, later buying an Allen licence to build compound bows. In 1972, Len Subber had interested Graham in a gadget he called the "Zipbow"; by 1974, Subber had come up with a modified design:- an upper recurve limb of fibre-glass and wood laminations with a double "nock" attachment from which two strings descended past a handle riser. Here the resemblance to a bow virtually disappeared, as bolted to the lower part of the handle riser was a pair of rigid metal plates only two-thirds of the length of the upper limb; between the plates were the axles for twin cams, around which the strings were led and secured. Given the title of the "Dynabo", the cast of this weapon was excellent and with a let-off of draw weight adjustable from 20% to 50%, the user soon became accustomed to the rather strange 'rocking' sensation of the draw, not to speak of the very peculiar appearance of the 'bow' - vaguely reminiscent of a man standing on his knees.
This tolerance was not shared by the authorities, who promptly banned it. It had only one working limb and was therefore "not a bow". The restrictions were only lifted when a later version was produced with a lower limb of composite construction, equally short and massive, but having a token degree of flex to bring it within the rules.
(Graham sold his Allen licence in 1981, since when he continued to produce the "Dynabo", available in three models and quite popular with bow-hunters during the 1980's.
The 1977 "Archers Digest" lists 100 different models of compound bow - but fewer than 50 recurves. After only eight years in production, two thirds of the market had been taken by the compound - a remarkable phenomenon.
Parallel with the evolution of the compound bow was the development of various accessories, including release aids, with a bewildering number of types of hook, trigger, cable and strap releases the latter recalling the Turkish "flipper". If all these were not sufficient to produce a perfect loose, the deviation of the arrow as it passed the new varieties of arrow rest was minimised by the new adjustable "cushion plunger".
Coming into the 1980's. three categories of compound bow are still discernible. the tip-to-tip cable system, with an eccentric wheel at each limb tip, the limb-to-handle cable system with four or six wheels, and the "Dynabo", which by this time had displaced the "Kam-Act" from the scene: but by the 1990's 'Dynabos' had disappeared from advertisements in Archery magazines.
By 1988, compounds were remarkably uniform, surprisingly like the original Allen patent drawing. many having cams; but there were two problems: the wheels or cams were narrower in order to try and minimise the recurring problem of bow limb torque; narrower wheels brought the string (and, hence, the arrow) closer to the cables near the centre line of the bow: inevitably, the arrow collided with the cables. One or two manufactures widened the wheels; all others added a "cable guard", an angled bar extending from the back of the handle riser to beyond the cables, nudging the cables off centre, out of the arrow path. This ugly addition now disfigures almost every compound bow on the market. But, as we shall see later, there is one notable exception.
For compound bows with a cam or eccentric wheel at each limb-tip (the majority of models) careful adjustments have to be made to the cable lengths and the bolt at the base of the bow limb which adjusts the tension in the limb. Spanners, pliers, screwdrivers are used: the bow must be Tuned, so that both bow-limb tips move in precisely the same path as the bow is drawn and loosed. Much fuss, effort and hard work has been expended in the past twenty-five years in efforts to iron out this problem.
For the Romans, faced with the same problem two thousand and twenty-five years ago when the bow limbs of their arrow-shooting catapults needed to be synchronised, the solution was simple: Vitruvius, writing in twenty-five B.C., stated that the competent artilleryman in charge should have an ear for music. (Presumably he adjusted the tension in each spring, tapping either side with the lever till the musical note emitted was at exactly the same pitch.) Now, that WAS tuning !
Many odd designs have appeared briefly on the compound bow scene over the years, and faded out again. First introduced in 1982, one that has survived the evolutionary test was designed by an American, John Islas. The appearance of the bow is bizarre, and the action grotesque: as it is being drawn, the limbs appear to be breaking apart: but the archer experiences (to his astonishment) a smooth and recoil-free shot. The bow is the 'Oneida Eagle', made by Oneida Labs, of New York State.
The cast of the bow is excellent, comparable with that of the best compounds: but how is it achieved?
At either end of the weapon is a short recurved bow limb, with a string attached to each nock, and in the centre is a handle riser; but there ends the similarity with a normal bow. If carrying such a bow into the headquarters of the Royal Toxophilite Society, the working parts (as on certain Classical statues) should be discreetly veiled! But we live in permissive times, so, with a warning that the explicit description hereunder may offend some readers, here is the secret of the 'Oneida Eagle'...
Between handle riser and bow limb is a short, solid fibreglass spring, which exerts a powerful leverage on the heel of the bow limb... Now, where have we heard a similar description before?
'At either side of the weapon is a frame: over each frame is stretched a skein of sinew-rope: in the centre of the skein is embedded the heel of a recurved bow limb. When fully tensioned, the spring of twisted sinew exerts a powerful leverage on the heel of the bow limb: the tips of the limbs are connected by a cord . '
Invented by the Greeks, (who called them 'Katapeltes Ozubeles') and copied by the Romans, the description is of an arrow-shooting catapult of the third century B.C. a good representation of one of these is carved on a frieze set up in about 228 B.C. by King Attalus I on a terrace of the temple to Athena in Pergamum. The carvings, representing captured weapons, were commissioned to commemorate victories by Pergamum over the forces of Antiochus Hierax and his allies the Tectosages and Tolistoagii (two tribes from Galacia).
The proportions and detail showed that the sculptor (perhaps Eumenes himself) knew his weaponry: comparing the size of the Ionian type of round shield depicted, with the visible bow limb, the latter must have been quite short, not more than 30cm. or so in fact, not unlike the bow limbs of the 'Oneida Eagle'; and it is clear from the outline that this catapult bow limb was of composite construction. This weapon, with its stock, frames, and supply of war arrows, would have needed two men, perhaps with a mule, to transport it. Yet the principle -applying leverage to the base of a short recurved bow limb- is very like that of the 'Oneida Eagle'. The modern weapon has one advantage: the user does not need an ear for music! The 'Oneida Eagle' has its own built-in 'tuner'; a timing wheel is attached to the cam which boosts the spring. A cable runs from the timing wheel through the handle riser to the equivalent timing wheel at the other end of the weapon, ensuring that both cam assemblies and bow limbs move in synchronisation as the bow is drawn and shot.
For ordinary compound bows, Tom Jennings, who first spotted their potential back in 1967, now claims to have solved the problem of tuning (timing) with the 'one-cam system': "the one-cam, un-cam bow that never goes out of time", claim the advertisements for Jennings' latest design, the 'Uniforce'. (It was in fact one Matt McPherson who invented the one-cam system; and the patent rights were purchased by Bear Archery). How did Tom Jennings get involved?
By an extraordinary twist of fate, Jennings Compound Bows became involved in a bitter legal dispute with the Allen Corporation, and in 1983 was 'taken over' by the Bear Archery Company: Wisely, they also 'took over' Tom Jennings as their chief designer. He had long recognised that the action of cams at each limb-tip must be exactly synchronised. The Jennings 'Unistar' was one of the first attempts to prevent the problem; twin cams were attached together, back-to-back on a pylon just below the centre of the handle riser, while the wheels at the limb-tips were plain pulley-wheels, (idler wheels), which had no multiplying effect, merely changing the direction of the string.
Now, in 1994, the 'Uniforce' compound bow features a cam on the lower limb-tip, with an 'idler' wheel on the upper - a system operated by a string made of non-stretch modern fibre, no cables being required. The advertisements claim, not only that this bow never 'goes out of time', but also that bow torque (which has been a problem affecting every bow with wheels cams or eccentrics at both limb-tips) is entirely eliminated. Yet a cable guard is necessary, so the strings must approach the cam at a slight angle: It would seem that further research is needed in the search for the ultimate compound bow. (We recall that the 'Dynabo' also featured a single cam and dispensed with a wheel on the upper limb...)
So, what does the future hold? The Turks used a horn groove to support the ends of their short flight arrows: with the realisation that a short light, faster broadhead arrow is more efficient than a long heavy slower one, overdraw shelves are now an almost universal option on compound bows for hunting. For anticipation of the future, perhaps we should look to the past... what happened to the arrow-shooting catapult?
The earliest types may have used sinew-rope for the springs, but King Attalus' arsenal at Pergamum, which specialised in the construction of catapults in the second half of the third century B.C. had probably discovered by then that horsehair rope was cheaper and easier to make, and could provide a lighter and more efficient spring.
About the same time as Attalus was setting up the victory frieze at Pergamum, an engineer named Philo was writing a treatise on artillery, in which he described experiments by one Ctesibus, who designed a catapult using two bronze springs in a vertical frame to provide the powerful pressure against the heel of each bow limb. An even more interesting concept was the use by Ctesibus of compressed-air springs: the heel of each bow limb, when the string was drawn back, would press against a bronze piston, which in turn would be pushed into a bronze cylinder, thus storing energy as compressed air. Though the standard of metal working must have been remarkably high for this to be tried, it doesn't appear to have proved a practical success, for no further records of its use have been found. But will history repeat itself? There seems no reason why, using modern materials, a compound bow powered by compressed air pressure on the heels of each short bow limb, on the lines of the Oneida Eagle, shouldn't be a practical proposition. Though the compound bow is now potentially more accurate than recurves (in the indoor F.I.T.A. round at 18 metres, the 40cm. target face has been modified with a smaller 10-ring for compound archers), easier to hold at full draw, and can shoot a lighter, faster arrow, it is still very far from perfection: much remains to be improved, and faults to be eliminated.
However, where bow-hunting is legal, it is widely accepted that the compound bow offers the bowhunter of moderate physique the best chance of success: commercial pressures will therefore ensure that its development will continue þ a fortunate and unparalleled opportunity for the student of archery history to follow, at first hand, the intensely interesting evolution of a new type of bow, bearing in mind the proposition that: "History in not just remembering, it is people acting and living their past in the present." (Prof. Bronowski)
Postscript:
The Hoyt-Easton Company was said some years ago to be still hoping to develop the perfect compound bow - all cables concealed in the handle riser and a single string attached to each nock- and this the very company that introduced the STABILISER (There may well be many a youngster this Christmas tinsel in hand turned sharply away by his mother. "No dear the tree is in the other room; THAT thing is your father's target bow!")
Stabilisers torque flight compensators and similar protrubelances are permitted by F.l.T.A. without limit to length or number provided that they are clear of the string the ground and nearby archers. The purpose of a gentle theme repeated in italics through this potted history of the compound bow is to put forward the suggestion that the forests of stabilisers on target lines are a greater affront to the traditions of archery than the "Force-draw multiplying attachments of Wilbur Allen's patent bow. "
Acknowledgement:
Having completed the main substance of this present article in the autumn of 1988, too late for publication in the journal, which was then going to press, the writer read and studied with the greatest interest and admiration the short history of the compound by the late George Jackson, which summarised in a concise and masterly way the progress of the bow up to its twenty-first birthday. The closing sentence of his article is just as relevant today as in 1988: despite all the research, the typical modern compound bow bears a striking resemblance to Allen's first prototype.
Bugger Bugger Bugger I forgot to check the Copyright before I posted, We dont have permission to post this unles the Copyright has expired !!
SD or MOD please delete this article I totally missed the Copyright bit on it .
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