The Ballistics of The Sling - Thom Richardson

This article had its genesis in the production of one of a series of five films made by the Royal Armouries and Yorkshire Television in 1997–8 for the American History Channel. The thrust of this series, as in so much of what the Royal Armouries is trying to achieve in its Leeds Museum, is to examine how arms and armour really work, and to dispel the myths and legends that have grown up around the subject. The film in question tells the story of Slings and spears, two of the earliest and simplest of weapons.

The bibliography of the sling is not extensive. Most of the literature has been produced quite recently, and comes from two very different approaches: the study of braiding (e.g. Cahlander 1980) and the (largely American) interest in survival skills and martial arts (e.g. Dohrenwend 1994). While the literature is thin, the extent of the weapon’s use across the world is remarkable (Korfmann 1973).

My relationship with the sling goes back over 20 years to archaeological excavation on Danebury hill fort under the directorship of Barry Cunliffe. The volume of sling stones excavated from the storage pits of the Celtic fort was such that hundredweights of them were deposited on the spoil heaps, providing an ideal opportunity to manufacture slings from lengths of string and practice using the weapon. It was there that I learned what is now termed in the technical literature on the subject the ‘whip’ technique of slinging, which I still find the most comfortable to use and the most effective.

The sling is formed of a length of cord with a loop at one end, a knot (or sometimes a plain end) at the other and a widened section, usually called a cradle, but not necessarily concave, at the centre. In all the techniques of slinging, the slingshot is placed at the centre of the cradle, the loop placed over the second finger of the right hand and the knot held between the thumb and first finger of the same hand. There are three techniques of casting the slingshot. In one, the ‘vertical whirl’, the sling is whirled anticlockwise (from the slinger’s viewpoint) and the knot released when the slingshot has reached the top of its arc. Alternatively the sling can be whirled clockwise, and the knot released at the bottom of its arc. Neither version of the technique is very effective, as it takes no advantage of the slinger’s arm, and does not generate much power in the cast.

The second technique, the ‘horizontal whirl’, is the most widely practised. The sling is held in the right hand as before, but with the arm raised above the right shoulder. The slingshot is placed in the cradle, and the cords levelled, by the left hand, which is also raised up above head level. The cradle is released by the left hand and the sling allowed to drop backwards over the head, then whirled around the head clockwise (again from the slinger’s viewpoint) a number of timed until sufficient momentum is built up. The knot is then released perpendicular to the body so the slingshot flies out straight ahead. This technique enables the angle of elevation to be varied for range, from an exactly horizontal arc for short range to an arc dipping quite deeply during its travel round the back of the body for long range.

Vegetius has a number of useful observations on the sling. ‘Slingers (funditores) shoot stones from slings made of flax or hair (the latter are said to be better) by whirling the arm around the head’ (Epitome rei militaris III.14). ‘Recruits should be thoroughly trained at throwing stones by hand and with slings. The inhabitants of the Balearic Islands are said to be the first to discover the use of slings, and to have practised with such expertise that their mothers did not let their small sons touch any food unless they had hit it with a sling stone. Often, against soldiers armoured with helmets, scale coats and mail shirts, smooth stones shot from a sling or staff sling are more dangerous than arrows, since while leaving the limbs intact they inflict a lethal wound, and the enemy dies from the blow of the stone without the loss of any blood’ (I.16). ‘They should also be accustomed to rotating the sling only once around the head, when the stone is discharged from it’ (II.23).

The horizontal whirl, then, was the standard release practised in the ancient west. While Vegetius, who had presumably never cast a sling in his life, recommends a single whirl round the head, presumably with a view to economy of time rather than practicality, other passages in classical literature give an idea of the normal release. ‘He drew tight a whistling slingshot on its thong, swung it round his head three times, hit his opponent in mid-temple with the now molten lead, and laid him full-length upon the sand’ (Vergil Aeneid IX.586–9).

The third technique, the ‘whip’, is largely practised in south east Asia and Oceania. The sling is held in the right hand as before, but with the hand held in front of the chest. The slingshot is placed in the cradle as before, but again with the left hand held low. When the cradle is released, the sling is swung back and down past the right side, until at the rear of the arc the slinger can feel the weight of the slingshot pulling at the second finger (the one holding the loop). It is then swung upwards and forwards, gathering momentum rapidly, until it reaches the perpendicular when the knot is released, often producing a whip-crack in the sling. The action is similar to a side-arm throw, or a baseball pitcher’s action. Lieutenant Baden-Powell of the Scots Guards described the technique in New Guinea in 1890, ‘ another primitive weapon of offence … especially at the east end, is the sling. A few stones are caried often nearly as big as one’s fist, and these are hurled with a twist of the arm very similar to the action of ordinary throwing (without twirling the sling around the head as is done elsewhere). The natives seem to vary a great deal in their ability … some being both marvellously good in both accuracy of aim and in great distance, perhaps 200 to 300 yards; while, on the other hand, many others are very feeble in their efforts (Ellis 1996). It is conceded by those who are aware of the third technique that it ‘imparts a greater acceleration to the projectile than the other two techniques’ (Dohrenwend 1994: 88).

Most of the slingers interested in writing about the subject come from the ‘survival’ school, and are more interested in the practicalities of using the weapon than in its history. Accordingly their slings are made of leather cradles and boot laces (see, for example, Blohm 1997) rather than being of braided construction. The braiders, meanwhile, are interested only in the slings as examples of techniques of braiding, and not as weapons, contemporary or historical.

Figure 1 - Egyptian sling of about 700 BC, excavated from El Lahun. University College, London, no. UC6921

To my knowledge only one sling survives from the ancient world (Burgess 1958). It is preserved in the Petrie Museum in University College London, no. UC.6921, and was excavated from El Lahun in the Fayum in Egypt in 1914 (figure 1, Petrie 1917: 36, V.14, pl. li). It was found alongside the remains of an iron spearhead (Petrie 1917: 32, H.175, pl. xl), and was thought by Petrie to date from about 800 bc. Only the loop end of the cord and the cradle survive, but from these the remainder of the sling can be reconstructed. The whole sling is braided from flax string. The main part of the cords are braided in a square sinnet of ten strands (see King 1960 for the easy way to do this), while the loop is formed of an ‘ear of corn’ braid of nine strands, one end of the loop being formed of a smaller loop of a simple plait of five strands, which is worked into the start of the cord at the other end of the loop. Curiously the braiding is almost identical to that used on type I braids worked downwards found on Peruvian slings of the 19th and 20th centuries (Cahlander 1980: 34–6, fig 4.9). The cradle is woven from the same material, and has a small fabric of a fine-weave fabric adhering to one side, which is probably not original to the sling. The cradle is 125 x 70 mm, and the remains of the single cord 570 mm. The cord is about 6 mm square in section. The original length of the sling, assuming that no parts of the fragmentary cord are missing, would have been 1270 mm.

Burgess reported that his reconstruction (also in the Petrie Museum) was remarkably laborious, but experience shows that the process becomes a great deal easier with practice coupled with taught braiding techniques. Burgess’s (and my) laborious frame-woven cradles were clearly not made the easiest way, either. For the experiments described below, I braided a number of slings copying the Egyptian sling (figure 2). Each weighs 45 g, and is 1450 mm in length.

Experiment shows that there is an optimum weight range of slingshot for a given sling. The minimum weight seems to be just under the weight of the sling itself; too light a projectile and it will drop out of the cradle before it is up to speed, or tend to hang in the cradle on release, before shooting out at random (and usually to the slinger’s left). Too heavy a slingshot will be very painful on the release finger, and tends to be released at rather low velocity.

Very few sling lengths have been published. One published example from Tibet is 2800 mm in length, while another from Yemen is recorded as 1600 mm (Collingwood 1987). A Peruvian sling of alpaca wool, probably 19th-century, is 1697 mm long, while a heavy (14 oz) llama wool example from Bolivia is 2178 mm long (Bailey 1998).

Figure 2 - Reconstruction of the Egyptian sling

The potential range of the sling has been the subject, like the potential range of the longbow, of considerable speculation. To the best of my knowledge no scientific measurement has previously been carried out. Part of the problem is the passage from Xenophon in which the 10,000, in their retreat from the disaster at Cunaxa, needed some light troops to deal with the pursuing Persian army. ‘There are some Rhodians, I hear, in our army, and they say that most of them know how to use a sling. Their weapon, too, has actually twice the range of the Persian sling. Persian slings do not carry far because they use stones as big as one’s fist for firing; but the Rhodians know how to use leaden bullets (molybdisin) as well … Then the Rhodians, who were posted in the Greek ranks, used their slings and the archers shot their arrows, and no one failed to hit a man … and Tissaphernes got out of range with alacrity, as did the rest of his army … The barbarians did no further damage by their old methods of long-range fighting since the Rhodians could sling further than the Persian slingers and their archers.’ (Anabasis III.3–4)

This has inspired remarkable claims for the maximum range of the sling. The more conservative estimates are around the 200 m mark (Ferrill 1985: 25), Connolly suggests 350 m (1981: 49), Korfmann estimates 400 m (1973: 37) while Demmin and Hogg go to 500 m (1893: 876; 1968: 30). The few accurately recorded observations are rather different. Reid records 55 m with a 227 g stone, and 91 m with 85 and 113 g balls (1976: 21). Burgess threw stones with his reconstructed Lahun sling between 50 and 100 yds, but admits to being unskilled at the art (1958: 230). Korfmann observed Turkish shepherds sling ordinary pebbles, ‘in 5 out of 11 trials the pebbles reached 200 m, and the three best casts were between 230 and 240 m (1973), while Dohrenwend has himself thrown beach pebbles over 200 yds (1994: 86).

I set out, therefore, to measure accurately a set of casts from a replica of the Egyptian sling, with a variety of ammunition. The results are recorded in table 1. Casts of lead slingshot tend to be very consistent, while those of stones of the same mass vary widely. Oval stones always travel furthest, and can go very well indeed, at best equalling the performance of lead balls (but not lead slingshot). However, on average lead slingshot outrange stones by about 50 %.

 

Table 1: Sling Ranges

slingshot

average

best

lead slingshot 40 g

145 m

150 m

lead slingshot 85 g

120 m

130 m

lead ball 38 g

114 m

115 m

lead ball 100 g

107 m

120 m

stones 45-75 g

90 m

106 m

stones 80-85 g

84 m

105 m

stones 85-160 g

82 m

115 m

 
 
Hellenistic almond-shaped lead projectile

Lead slingshot are almond-shaped (sometimes called biconical, though this hardly expresses the subtlety of their shape). Two examples obtained by the writer were copied for testing. Both are Hellenistic, and from the Lebanon. The smaller, cast with a thunderbolt in relief, weighs 35 g, and measures 29 x 18 x 13 mm (copies taken from a mould of this and used for testing weighed an average of 40 g). The larger, plain, weighs 86 g, and measures 39 x 22 x 16 mm. Lead slingshot of this type appear in the 5th century bc, and continue throughout the Hellenistic period. The best known find is the group of some 500 from Olynthus excavated in the 1930s. These varied in weight from 18 to 35 g (see Korfmann 1973). Many of the Greek examples are cast with raised symbols or inscriptions, such as the ‘phaine’ example presented by Hawkins to the Society of Antiquaries (1847: 96). The lightness of these slingshot suggest to the author that they may have been designed to be cast in groups or pairs, which produces a shotgun effect. Although this has never been suggested in the scholarly literature on the subject, it works well by experiment, and is well known to the ‘survival’ school of slingers (Blohm 1997). The effectiveness of lead slingshot was well known in the classical world. Celsus includes instructions for extracting lead and stone slingshot from the bodies of wounded soldiers (De Medicina, cited by Korfmann 1973).

In Latin the word glans is used for the slingshot, and funda for the sling. Republican Roman examples are found at Perugia (Griffiths 1989: 267–9), early Imperial examples from St Albans, Antonine examples from Burnswark, and late Imperial examples from Vindolanda (Greep 1987). From the Republic onwards they are joined by baked clay slingshot, the earliest examples coming from Numantia, the latest from the 4th century at Lambaesis. Shaped stone missiles, such as those from Buciumi, and others from Lambaensis, are found from the 3rd century onwards (Bishop & Coulston 1993: 55, 79, 115, 139,165–6). No systematic study of ancient lead slingshot has ever been carried out, however.

My range tests indicate a much shorter range than has been previously asserted. This may because I have not learned to sling within a sling-using culture, or because I am inept at it. Alternately, claims for the range of the sling may have been exaggerated. The difficulties of measuring the range of a sling are not insignificant. Having cast a stone a considerable distance, you then have to find it. One (dangerous) solution to the problem is to post a spotter down the range. This works very well for stones, whose flight can be followed. The problem comes with lead slingshot, whose flight can usually not be followed, and whose arrival can only be heard. It is certain that more controlled testing is needed, and I would be very pleased to hear from slingers who have scientific data on the subject.

The making of the films by Yorkshire Television also enabled the Museum to use the facilities of Vickers Defence Systems at Ridsdale. The ballistic testing undertaken there forms the subject of the following article, but the sling tests are discussed in more detail here (Table 2). The slingshot speeds recorded were extremely consistent. Stones performed consistently worse than any kind of lead shot, using exactly the same slinging action. Cast lead slingshot performed better than spherical lead balls or stones, but only slightly better; in terms of velocity alone, an improvement in performance of about 3%. Their lower drag is responsible for the far larger differential in ranges noted above.

 

Table 2: Sling Velocity

slingshot type

lowest V (m/s)

average V (m/s)

highest V (m/s)

85 g lead slingshot

29.9

31.2

32.6

40 g lead slingshot

29.3

30.6

32.5

100g lead ball

29.5

30.5

31.4

80-100 g stones

29.1

30.3

32.2

staff sling

29.4

33.1

38.3


It is noteworthy that even using the sophisticated skyscreen at Ridsdale, considerable accuracy was required to enable the slingshot to pass through the 1 m wide arc which was set at 3 m from the release point. This, as other testers have found, tends to a reduction in velocity. A simple calculation (or observation) shows that a slingshot travelling over a range of 90 m at a velocity of 30 m/s takes about 3 seconds to reach its target, while a slingshot travelling over a range of 145 m at the same speed takes 5 seconds. A good cast is usually accompanied by a whirring noise, from all types of projectile, as it spins through the air.

The staff sling or fustibalus is interesting. It is first described by Vegetius in his Epitoma Rei Militaris ‘Staff slingers are those who cast stones from a staff sling. The staff sling is a pole (fustis) four feet (1180 mm) long, attached to the middle of which is a sling of leather, which, operated with both hands, it discharges stones almost like a mangonel (onager)’ (III.14). Vegetius is also responsible for the only mention of the range of a sling in the entire corpus of ancient literature, and although this is often quoted of the sling, it clearly refers to the staff sling: ‘archers and slingers used to put up bundles of straw as targets, and moving back to a range of 600 ft (= 177 m), practise hitting them frequently with arrows and stones shot from staff slings’ (II.23; Millner 1993: 91, 57). For the continued use of the sling and staff sling in the Byzantine period, see Kolias (1988: 254–9).

The staff sling continued to be popular in Spain until the late 14th century, being used to considerable effect at the battle of Aljubarota in 1382. Olaus Magnus illustrates and discusses staff slings throwing red-hot chunks of iron during the siege of King Christian II of Denmark at Vasterås in 1521. From what he says it appears to have been a common weapon of the Dalecarlians (from Dalarna, north west of Stockholm; Foote 1998: 332–3). He also says that ‘pole slings’ were used by the Finns to drive back preliminary assaults, ‘then, when they are about to contend at close quarters they defend themselves with the sling stones they keep knotted at their belts’ (Foote 1998: 536).

Although the staff sling discharges the stone faster than the sling, and consistently outranges it, it has the disadvantage that it can only be used at long range, discharging the stone in a high arc. The sling can be used at short range as well, simply by adjusting the angle of the arm at release, in exactly the same way as throwing. Using the ‘whip’ release rather than the ‘horizontal whirl’, a slinger can match shots almost exactly with an archer, casting five or six a minute at full speed.

Another version of the sling, the kestros or kestrosphendone, was invented at the time of the Third Macedonian war of 168 bc. It is described by Polybius, ‘the missile was like this: it was two palms long, with a socket and head of equal length. Into the former was fitted a wooden haft a span in length and a finger’s breadth in thickness. To the middle of this were attached three flights of wood, quite short. This, its sling having two unequal cords (kolon), was fitted in the centre of the cords in such a way that it was easy to loose. There it remained while the sling was whirled round, but at the moment of discharge, when one of the cords was released, it left the cradle (agkules) like a lead slingshot from a sling and striking with great force severely injured those who were hit by it’ (XXVII.11). Livy’s translation adds little; ‘ In this war a new type of missile was invented. A head two palms long was fixed to a haft half a cubit long and the diameter of a finger; the latter was fitted with three pine flights, as arrows are; the sling had two unequal loops at its centre. When the slinger rotated the cords, it remained poised, and when released flew off like a lead slingshot’ (XLII.65.9). To the best of my knowledge the cestrosphendone has never been reconstructed, and I cannot see quite how the unequal length cords work. Possibly the cradle is divided like those of Peruvian slings, but formed of two unequal loops so that the head of the cestros points forward during rotation, and starts off its flight in a head-forward attitude, rather than tumbling until it finds equilibrium. Or, perhaps, the butt of the cestros is lodged in one loop of an unequal cradle, the side of the head resting against the other. Again, I would be interested to hear from anyone who has experimented with a reconstruction.

The sling and the bow have much in common, and it is remarkable that in the West archery has continued to become the popular sport that it is, while slinging is the preserve of a few strange enthusiasts. It is to be hoped that the articles that have appeared over the last few years are the beginning of a revival in the study of the sling and its use. A cautionary note, however, to end on; slinging is not an occupation which can be undertaken safely, especially by a beginner, as the missile must be heavy enough to extend the sling, and can go almost anywhere on release. The job of sling instructor must have been one of the most dangerous in history.

- Thom Richardson

Copied with permission from:
Thom Richardson, "The ballistics of the sling," Royal Armouries Yearbook, 3, 1998, p. 44.

Royal Armouries, Leeds, UK

 

Acknowledgements

I am indebted to various people for help with the research that went into this article. Thanks to Peter Smithurst of the Royal Armouries for casting the slingshot used in the testing; Graeme Rimer, Mark Murray-Flutter and Martin Pegler, all of the Royal Armouries, for bravery beyond the call of duty during the range testing; Paula Turner, for helping with months of sling braiding; Guy Wilson, for consultation on matters Scandinavian; and to Michael Elliot and Phil Breckons of Royal Ordnance for the ballistic data.


References

  • Bailey, T. 1998 The sling. www.crl.com/~mjr/tbailey/sling.htm
  • Blohm, B. 1997 Slings as hunting weapons. Primitive-skills-group, www.uqac.uquebec.ca/PleinAir/huntisl1.htm
  • Burgess, E. M. 1958 An ancient Egyptian sling reconstructed. Journal of the Arms and Armour Society 2.10 June: 226–30
  • Cahlander, A. 1980 Sling braiding of the Andes. Colorado Fiber Center, Boulder
  • Collingwood, P. 1987 The maker’s hand. Lark Books and Interweave Press
  • Connolly, P. 1981 Greece and Rome at war.
  • Demmin, A. 1893 Die Kriegswaffen im ihren Geschichtlichen Entwickelungen von den Ältesten Zeiten bis auf den Gegenwart. Leipzig, P Friesenhahn
  • Dohrenwend, R. E. 1994 The sling: forgotten firepower of antiquity. Canadian Journal of Arms Collecting. 32.3 August: 85–91
  • Ferrill, A. 1985 The origins of war. London, Thames and Hudson
  • Foote, P. G. (ed.) 1998 Olaus magnus, a description of the Northern peoples 1555. The Hakluyt Society, second series no. 187, vol. 2
  • Greep, S. J. 1987 Lead sling shot from Windridge farm, St Albans and the use of the sling by the Roman army in Britain. Britannia 18: 183–200
  • Griffiths, W. B. 1989 The sling and its place in the Roman Imperial army. In C van Driel-Murray, Roman military equipment: the sources of evidence. Proceedings of the fifth • • Roman Military Equipment Conference, BAR International Series 476, Oxford:255–79
  • Hawkins, W. 1847 Observations on the use of the sling, as a warlike weapon, among the ancients.
  • Archaeologia 32: 96–107
  • Hogg, O. F. 1968 Clubs to cannon. London
  • King, F. H. 1960 A note on the square sinnet. Journal of the Arms and Armour Society 3.7 September: 187
  • Knight, E. H. 1880 A study of savage weapons at the Centennial Exhibition, Philadelphia, 1876. Smithsonian Institute Report 1879: 213–97
  • Korfmann, M. 1973 The sling as a weapon. Scientific American 229.4 October: 34–42
  • Millner, N. P. 1993 Vegetius: Epitome of Military Science. Liverpool University Press
  • O’Leary, S. 1975 More about the sling. Slingshot 57 January: 23–8
  • Petrie, W. M. F. 1917 Tools and weapons. London, British School of Archaeology in Egypt
  • Reid. W. 1976 Arms through the ages. Harper & Row, New York & London
  • Willis, B. F. 1996 Military sling-shot in 1890. Canadian Journal of Arms Collecting 34.4 November: 127

 

Captions

  1. Egyptian sling of about 700 bc, excavated from El Lahun. University College, London, no. UC.6921.
  2. Reconstruction of the Egyptian sling, by the author.
  3. Hellenistic lead slingshot, weighing 35 and 86 g, in the possession of the author. 
  4. Sling stone weighing 112 g.
  5. The ‘horizontal whirl’ technique.
  6. The ‘whip’ technique.
  7. The staff sling technique.