PhotosbyKev

Images taken with a high speed flash system based on the Mumford Time Machine to observe the rifling on a lead pellet fired from an air rifle.

The rifle is a Daystate Mk4 kindly modified by Daystate to give me a large level of control over the pellet velocity. The pellets are 0.177 Air Arms Diabolo Field.

The flashgun is being triggered by an IR beam across the muzzle of the rifle.

The following image is a crop from the previous photograph showing the rifling marks left on the pellet

These images are taken after a pellet was retrieved and shows the rifling on the pellet skirt and dome

Power and Pellet Deformation

The following image is of two pellets fired at differing power levels and velocities.
The left hand pellet was shot at 85 fps and the right hand pellet was at 780 fps.

The depth of the rifling has been significantly increased on the right hand pellet due to the skirt being expanded further into the barrel rifling. There is also a hint of deformation in the flat side of the skirt due to the increase in power or from the landing impact? In order to take the second shot at full power and retrieve an undamaged pellet I was shooting at a fluffy cushion over 250 yards away, eventually I managed to land a pellet on it it would of been a lot easier with ballistic gel. My thanks goes to a friend who was prepared to trudge up and down the field to check if I’d hit it because I didn’t have a clue!

Using a Mumford Time machine and a ballistic sensor it is relatively easy to capture the flight of a 0.177 air gun pellet going through objects.

The timing on this was planned to make sure the pellet was completely out of the image so a multipler of 8 was used on the Time machine so the pellet was long gone. The internal pressure in the Red Bull can has caused the top to fail.

A light bulb captured just as an air gun pellet exits the bulb on the left hand side. Two Canon 580Ex flashguns were used to illuminate the event and they were set at 1/128 of full power.

A 5 second exposure was taken which allowed me time to manually fire a flashgun behind the cigarette to get the smoke trail and then fire an air gun pellet through the cigarette, this event was captured by a flashgun on 1/128 full power which was triggered by a Mumford time machine.

A playing card being struck by an air gun pellet. In order to get the spray on this image I taped a small teabag to the rear of the card that I had filled with talcum powder.

Two 580Ex flashguns were used both on the right hand side of the camera about 150mm from the playing card. They were manually set to 1/128 of full power to get the very short flash duration required. To trigger the flashguns at the right time the ballistic sensor attached to a Mumford time machine was used.

1 second exposure @ f22 iso 200 using a Canon 40D and 100mm macro lens.

This image is taken with two Canon 580Ex flashguns placed about 100mm from the candle. The main flashgun is triggered directly from the Time Machine and the second gun triggered wirelessly from the first gun.

Both guns were set to 1/128 of full power and a multiplier of 2 was used to trigger the flashguns when the pellet was 200mm (8″) from the end of the sensor tube. The candle was positioned about 7″ from the sensor so the event would be captured after the pellet had passed through the candle.

The ballistic sensor also measures the velocity of the pellet and in this instance it was travelling at 433 feet/sec, that’s approximately 130m/sec. During the flash duration of 1/35,000sec the pellet will have travelled almost 4 millimetres and is just visible at the edge of the spray.

An exposure of 1 second @ f22 iso 100 was used in a darkened room. The camera shutter was manually triggered just before firing the air gun. The 1 second exposure has captured the flame as it was dragged away from the candle wick by the pressure wave from the pellet and the initial impact.

This image is of a small cherry tomato being struck by a 0.177 air gun pellet travelling at 433 fps.

Again two Canon 580Ex flashguns were used to capture the event. One in front of the tomato and one behind to backlight the spray of the juice. Both guns were set on 1/64 of full power and zoomed to 70mm to increase the light on the subject.

Exposure was 1 second @ f11 iso 200 taken in a darkened room. Taken on a Canon EOS 40D and 100mm macro lens. Interesting to see the spray travelling backwards from the entry point of the pellet.