Harris Despatch on War Operations, in Appendix D, paragraph 82, talks about receiving the intelligence about upward firing guns in August 1944 and an examination ordered of previous damage suggested first use in January 1944, being used in about 10% of non lethal fighter attacks. There was a considerable increase in damage from upward firing guns in late 1944 and early 1945.
If you shoot straight in front of plane bullets curve down, if you shoot directly up the bullets curve back due to plane speed. There is an angle degree where bullet path goes in straight line! Where gravity of bullet is balanced by speed of plane. Apparently ace Albert Ball (SE5a in WW1) was expert at this.
Trouble is the diagram is a bit out of scale. The principle is correct but the time of flight and the movement of the aircraft involved make the practical application a lot harder to pull off. The practical difference in using no allowance shooting and "allowance shooting" is not going to be all that great. At least until your bullets are over 45 degrees to the wind and you are shooting fairly long range.
And since the bullet changes speed due to drag as it travels the "straight" line is only going to last a short period of time. It may be all you need for short range combat but it will leave a lot to be desired for long range shooting.
And let's think about it. The only way that gravity can balance the speed of the plane is by going down, not up.
The bullet will never going as fast as it was when it left the muzzle.
Assuming the bullet leaves the muzzle at 750m/s you can add the speed of the plane if the gun is pointed along the axis of the plane and start taking away speed as the gun swings closer to 90 degrees to the axis and then keep taking away velocity as the gun swings through the rear arc until minimum speed is reached in the direct opposite of the direction of travel that plane is going.
Now even gravity is not going to make up for the aerodynamic drag of the projectile as it slows down after leaving the muzzle. The higher velocity of the bullet when fired into the forward arc means a higher of velocity decay due to higher drag. Bullets can slow by several hundred meters per second in the first 200-300 meters of flight.
I think somebody had one or two extra G & T's at the officers mess when coming up with this therory.
Wasn't the counter to being attacked from below Fishpond?
The wireless operator could detect aircraft below and instruct the pilot to change course. If the spot followed you, you knew it was likely unfriendly.
No guarantee of escape, but at least you knew what was coming...
Wasn't the counter to being attacked from below Fishpond?
The wireless operator could detect aircraft below and instruct the pilot to change course. If the spot followed you, you knew it was likely unfriendly.
No guarantee of escape, but at least you knew what was coming...
Then there was Fishpond. That was an attachment to the H2S ground mapping radar. But not all aircraft received H2S. And the Germans also had a detector for those signals, Naxos, but don't seem to have used it as a "homer", but just as a warning system.
Naxos was indeed a homer on H2S but Fishpond required much less power
To quote from your wiki article on H2S
One problem was that the returns from closer objects were much stronger than more distant objects, due to the radar equation.
It could also be used independently of H2S and I believe the instructions were to not keep H2S on permanently, but wish Fishpond the benefits outweighed the risk.