Do Bombs Ever 'Overtake' the Aircraft that Dropped Them?

hi,
as you say most are ricochets, but a search produced this from Aerofiles-

On Sep 21, 1956 Grumman test pilot Tom Attridge shot himself down in a graphic demonstration of two objects occupying the wrong place at the same time—one being a Grumman F11F-1 Tiger [138260], the other a gaggle of its own bullets..

It happened on the second run of test-firing four 20mm cannon at Mach 1.0 speeds. At 20,000′ Attridge entered a shallow dive of 20°, accelerating in afterburner, and at 13,000′ pulled the trigger for a four-second burst, then another to empty the belts. During the firing run the F11F continued its descent, and upon arriving at 7,000′, the armor-glass windshield was struck, but not penetrated, by an object..

Attridge throttled back to slow down and prevent cave-in of the windshield, flying back to Grumman’s Long Island field at 230 mph. He radioed that a gash in the outboard side of the right engine’s intake lip was the only apparent sign of damage other than for the glass, but that 78 percent was maximum available power without engine roughness occurring..

Two miles from base, at 1,200′ with flaps and wheels down, it became evident from the sink rate that the runway could not be gained on 78 percent power. Attridge applied power and said “the engine sounded like it was tearing up.” It then lost power completely. He pulled up the gear and settled into trees less than a mile short of the runway, traveling 300 feet and losing a right wing and stabilizer in the process. Fire broke out, but, despite injuries, Attridge managed to exit the plane and get away safely, to be picked up by Grumman’s rescue helicopter.

Examination of the F11F established there were three hits—in the windshield, the right engine intake, and the nose cone. The engine’s inlet guide vanes were struck, and a battered 20mm projectile was found in the first compressor stage..

How did this happen? The combination of conditions reponsible for the event was (1) the decay in projectile velocity and trajectory drop; (2) the approximate 0.5-G descent of the F11F, due in part to its nose pitching down from firing low-mounted guns; (3) alignment of the boresight line of 0° to the line of flight. With that 0.5-G dive, Attridge had flown below the trajectory of his bullets and, 11 seconds later, flew through them as their flight paths met..

regards,
jack…

hi,
apologies for a little thread drift, but I’m sure a USAF fighter in the 50/60’s shot itself down…by firing its guns, diving and then pulling up into the stream of shells…

regards,
jack…

Ricochets from the ground targets are the “usual” cause. It has happened much more recently than WW2 – I remember a Jaguar receiving a hole (and 30mm projectile) in the Stbd wing next to the OB pylon at Decimomannu in 83/84.
😎

From 3/4 above and ahead anything dropped would appear to emerge from under the nose of the aircraft and then move ahead of it, but the brain would normally, with instinctive understanding of perspective, correctly interpret this as objects dropping essentially downwards.

However, the effect of ‘foreshortening’ by a long lens would probably mean that their rapid decent would be less visible in terms of reduction in relative size than the apparent (not real) relative movement in the horizontal plane – creating something of an illusion of forward motion relative to the aircraft.

Is this what is called ‘parallax error’, or is that something else?

I reverted back to my Aeronautical Engineering degree knowledge there on mechanics/dynamics/fluids, it was a few years ago!

An interesting comment there and you highlight all the forces acting on the bomb. If lift was generated, and it could well be, this would also be a vertical component, acting upwards and against gravity, but it wouldn’t be a horizontal force. In affect you have 4 forces (Thrust/Drag/Lift/Gravity) acting in effect forwards, backwards, up and down and the forces can be resolved into these 4 planes.

A glider shouldn’t be able to overtake a towing aircraft unless that aircraft reduced speed rapidly for some reason (suddenly lost power for example).

Interesting stuff and I’ve seen numerous films day and night USAF and RAF that “appear” to show bombs overtaking, but I think it’s a factor of being taken from above in a moving aircraft and angles and such.

…gravity will only work in the vertical, giving a vertical vector to the trajectory, there is no gravitational horizontal component.

Yes, this is what I couldn’t quite get my head round last night but the only way I could imagine a horizontal ‘gravitational’ component was if there was some form of significant lift generated by the bomb, and I couldn’t see that from an ordinary ‘dumb’ bomb.

Put it this way, as an extreme example, after release, can a glider ever overtake the towing aircraft? I’m going to say yes, powered only by gravity, but then a bomb is not a glider is it.

Read something about a WWII pilot too
Cees

hi,
apologies for a little thread drift, but I’m sure a USAF fighter in the 50/60’s shot itself down…by firing its guns, diving and then pulling up into the stream of shells…

regards,
jack…

Gravity will have an affect clearly (which is why the bomb falls) but to understand the forces and dynamics at play will help understand in that gravity will only work in the vertical, giving a vertical vector to the trajectory, there is no gravitational horizontal component. The only horizontal components giving a horizontal vector will be from the aircraft and bombs speed (and drag/air pressure on release) so adding these forces onto the trajectory will see the bomb loose horizontal speed and gain vertical speed, but the horizontal speed will never exceed that of the carrier aircraft.

Yes, the toss-bombing diagrams always seem to show the bomb way ahead of the aircraft but that’s not possible; it’s just a diagrammatic convention because the aircraft is further away from the target but by virtue of the turn and change of direction.

Low level bombing presents a problem because the bomb doesn’t have enough time in the air to slow down so it detonates too close to the aircraft (if a retarding tail is not fitted); you can’t change the rate the bomb falls so, as you say, you have to increase the rate it slows down.

It depends on what you are doing, the Jag used to toss bomb, i.e. Pull up from low level, throw it off in a fwd arc as it turned and descended, so in that case it would be out front for a time. Also remember a retard was designed to slow a bomb at low level to prevent detonation under the aircraft damaging it..
I suppose if you are doing 500kts a bomb dropped will be doing 500kts and accelerating due to gravity initially.

My thinking last night was that because gravity was acting on the bomb, and yet the bomb was ‘flying’ forwards with (initially) the speed of the aircraft, that the extra energy from gravity would accelerate the bomb forward past the aircraft, however, the bomb can’t (shouldn’t be able to) generate any lift from its forward speed so will fall at exactly the same speed as an identical, but stationary, bomb.

Therefore the bomb must always slow down from the moment it is released, relative to the aircraft (assuming that the aircraft is flying straight and level and is not dive-bombing with dive brakes extended).

This was also the reason for the Stuka to have the “swing bracket” under the fuselage to prevent the bomb from hitting the propeller.
Cees

With dive bombing the answer is yes, if the aircraft has dive brakes deployed it could soon be overtaken by the bomb(s) it has just released, if it doesn’t get hit by it/them and reduced to falling confetti. Level bombing, I don’t see how that could happen. Initially the bomb has no vertical speed, only forward speed (which is the same as the aircraft), as soon as it is clear of the bomb bay (and really a little before then) and into some meaningful airflow the forward speed begins to decay while gravity is pulling it remorselessly to the deck. If the forward speed of the aircraft was below the terminal velocity of the bomb then the bomb will not slow down, but will accelerate due to gravity until it reaches that terminal velocity, but when it does it will have virtually no forward speed and a very high vertical speed (if left to fall for long enough it should fall perpendicular to the gravitational field of the earth).

The only way I can see a bomb dropped in level flight overtaking the release aircraft is if the release aircraft slows down quite quickly. I know that the heavy bombers of WW2 tended to gain a bit of altitude when they lost a few tons in weight in one go. The change in pitch could cause a drop in airspeed which I guess could allow the bombs to briefly nudge ahead. Also if the aircraft’s attitude changes the perspective of the camera will have changed which could also give an odd impression.