Practical shooting

Execution with external catapult system

The clamping action

The stretching action  with the double-armed crank is without problems. With steep angles of incidence the shaft must be brought however into a suitable, almost horizontal position and then be shot back into the preselected elevator position.

The firing procedure

At first it occurred again and again when releasing the shot, since the chord was lifted by the clamping claw over the arrow. Therefore two compressor rods were attached which prevented, thus the firing procedure runs reproducibly without a problem.
Range of fire

Since  the beginning too much tension was chosen, the catapult was very difficult to stretch. As the safety aspect could not be neglected with the arising forces, we decided to use to that time a covering  reduced by the half. This resulted in one of the cases of later attempt ranges of fire to 200m, for demonstrations more than the appropriate range. The first firing attempts were accomplished on 10 m against polystyrene plates. In the case of the first free attempt ranges of fire to 100 m resulted in the case of angles of departure of 30°. With angles of 40° 200 m could be achieved. The range of fire adjustment  had proved itself ideally to the selected slot mechanism. Thus the range of fire without change of the firing angle lets itself adjust easily. The gun commander counts the rest procedures of the handle mechanism, which are to be noticed well acoustically while simple stretching. With the same slot number per shot same ranges are obtained. More slots adjusted increases the width. With fewer rest procedures it comes to a reduction. This particularly itself proved with the fast rate of fire as extremely favourable. The gun commander counts for example to slot No. 8 and gives the man at the clamping crank then the instruction „stop “.


Illustration 1

Interior catapult system. Shooting distance: 70m.
Target: round-clench of straw
With an angle of depature of 45° up behind the visible group of
shrubs shot, approx. 160m.

Accuracy of fire

So far the catapult was tested at a number of demonstrations. Usually one shot at 100m, usually without a target wall. With the same angle of departure and same pre-loading the arrows in the periphery came down for a of 2 - 3m radius. Man disks hit on to 50m of approx. 70% of the projectile pins. A 3x3m large target wall was hit always surely thereby. At a shooting demonstration on straw round bundles, all projectiles could be surely placed in the bundle after shooting on 70m.

Illustration 2
Doublette with outliers left.

A fundamental problem of double-armed torsion catapults is to be bring the two torsion systems into synchronous effect. This might have been also and just - because of the organic material of the clamping bundles (hair hurry or animal chords) a challenge for the ancient catapult operators. During shooting is recognized again and again that it comes to the shift of the chord from the catapult centre, since one of the chord bundles behaves differently like the second. This naturally leads to different energy releases from shot to shot, which then affects aiming the accuracy. Then the washer bolt must be pulled and readjusted by means of a stretching key.

In addition over to be able to shoot exactly reproducibly aerodynamic and weight-related as identical a projectile pins as possible are necessary.

Whether „the mass consumption commodity “projectile pin in ancient warfare of  this requirement were always fair is strongly doubted. External influences like changing counter or cross-wind substantially affect the accuracy of fire . Here - like also when readjusting the torsion bundles - only being able to and the experience help the catapult operation.


Striking power

The arrows with square point pierced 15 pieces of polystyrene plates of 20mm strength on 10m. 15mm fire wood will pierce distance up to the half of the arrow length on approx. 50m. With free attempts the arrows penetrated with impact up to a half in soft grass ground.

Note: By geometry of the projectile pins, slim easily con-like form, the wood shaft wedges itself with the penetration into the target.

Illustartion 3
Tangetial hit in clench.
Projectile 35 cm penetrated.  

Illustartion 4
The target misses. The grass is high. Luck had, the projectiles
are to be however recognized in the grass.

Problem of the catapult demonstration

Problematic always is the first shooting of the catapult. Arbitrarily free field of fire is never present. Always adjacent garden area is to be counted on land development. The organizers of Roman days usually have an unsatisfactory imaginative power of the firing performance of such a catapult. We use thereby only light exercise projectiles without point and do not provoke the achievement of the catapult. On short distances an "Oha" effect lets itself be obtained if a man disk moves or to fall down is also brought during low pre-loading. Also a flying range of 100m already makes a good impression. Nevertheless the shooting course and the condition range of the catapult should be generously closed off.



Illustration 5

Demonstartion of an external catapultsystem.


General statement

We state again and again that the catapult arouses the interest of the visitors also at static demonstration without a sharp shot. A certain optical elegance cannot be denied to the Trajan' Catapult. The concept of the torsional stress also excites astonishment, because it strongly deviates from the usual conception of an arrow- firer. The construction contains a certain growth potential concerning the possible firing power can still in attempts be determined can. Also in the future some smaller improvements are still made. Fortunately the construction proved itself as correct, necessary re machining of the measure which can be expected in principle did not exceed.


Change to an internal catapult system

Since one in the meantime assumes  that the catapult models of the Trajans Column had inward swivelling catapult arms,  the existing catapult No. 2 was converted into a variant with interior catapult system. Which first like appeared a short campaign developed to a consequence of in such a way not before seen problems. The change of the clamping frame, enlargement of the distance of the torsion sockets and the adjustment of the torsion stands (front prop now mirror-image) run without problems.
Since the fibre now stood however for approx. 40 cm before the clamping frame, the stock and the clamping carriage also had to be adapted and the hauling cable had to be extended. With the first firing tests already completely different characteristic of the new configuration came.
If the torsion bundles were linked up as usual, the clamping behaviour was in such a manner progressive that up to half of clamping stroke nothing more was possible. That was because of the possible clamping angle that had doubled itself now nearly and the normally usual stress was already reached after half clamping stroke.
One could ease the two torsion bundles almost completely and then nevertheless the complete clamping stroke, because of  the hard use of the necessary stress.

The substantially higher forces became also apparent thereby the catapult arms out off pure wood already broke after 5-6 shots. Only as the thicker wood (ash) and the break range with iron staffs were strengthened solved this problem. Further the catapult arms flew forward with the shot from the torsion bundles. An effect with the conventional catapult did not arise, since the catapult arms were pulled by the chord-power into the torsion bundles. Regarding range convincingly good results were obtained 150-200m with 350g heavy projectiles were loosely attainable. With light arrows of 250-300m were reached. A very pleasant effect was that one did not have to ease the torsion bundles after shooting for the indulgence of the clamping material. One knew the relatively small pre-loading was simply maintained. This has to do with the fact that thereby this version of the firing energy must bring in only then - under the large clamping angle - by shooting, while this must be kept ready by a higher pre-loading with the external system in the high measure from the front.

Text and pictures: Author