View Full Version : Parachute & Cable air defence at Hawkinge

Jun-30-2012, 01:26
Many innovative stategies were used to defend allied airfields during WW2, Some more effective than others. In addition to AA batteries, Kenley, Biggin Hill & Hawkinge airfields (& others) used a parachute & cable (PAC) system.

PAC consisted of a small rocket trailing a steel cable, which shot vertically 300-400ft into the air and then descended on parachute. The rockets were grouped in batteries of nine, to be launched simultaneously in a curtain pattern. The idea was that of creating a web of steel cables across the path of a low-flying aircraft, causing it to catch the wires and stall to the ground.

The parachute had a dual function. Once the rocket burned out, the canopy slowed the cable’s fall, allowing the “curtain” to stay up in the air for a longer time. Secondly, if the cable caught a bomber’s wing, the added drag from the parachute was hoped to be sufficient to foul its flight. There was also a smaller parachute at the lower end of the cable designed to balance the drag of the first one and thus prevent the cable from it from sliding off the wing of the aircraft. Later versions had an additional explosive charge hung at the bottom of the cable, intended to detonate on contact with the aircraft. The PAC system was effective deployed to defend Kenly airfield on 18th August 1940 ("the hardest day"), downing 2 of 9 low flying Do17s over the airfield.

I know the ATAG guys like hovering over Hawkinge (& other airfields) & strafing enemy planes either on the ground or as they takeoff. I'm OK with that, but Hawkinge did have the "parachute & cable" anti-air defence system (see http://www.airfieldinformationexchange.org/community/showthread.php?108-Hawkinge/page9 ).

Would ATAG consider 'installing' a PAC air defence at Hawkinge by incorporating the following script in their missions?

Code removed by the author

Jun-30-2012, 02:03
It would just be a visual effect till Maddox Games give those cables a collision model.
Seem to remember ATAG even started out with spotter Balloons around the airfields, but since they only had a visual function they were probably deleted to improve framerates.

So while I agree it would be cool, it might not be the best idea while people still suffer from lowish framerates and the cables serve no real function.

Jun-30-2012, 02:18
Salmo -

If I'm reading this right, the script will give about a 10% chance of "catching" an enemy plane if they are extremely low buzzing Hawkinge. Does that sound correct?

Very nicely done mate. I'll do some testing, but I don't see why not. :thumbsup:

@Warhound I don't think this is a physical/object based action - I think the script is a workaround for if there actually was a cable. Well at least I think so anyways. :S

Jun-30-2012, 02:40
Yes, Bliss. I'm aiming for about a 1:10 chance of PAC success if an enemy aircraft is in the danger zone over the airfield. The PAC success rate is influenced by several factors that can/will need to be adjusted in the script based on experience.
1. OnTick() -> Frequency of looking for blue aircraft over Hawkinge. This is set at each 60s at the moment. I'd be reluctant to make it any more frequent due to system resource use.
2. Area of PAC operations -> At the moment the script looks for blue aircraft in a cylinder that is 1500m diameter & 300m high over the centre of Hawkinge. The cyclinder size can be adjusted as desired. The smaller the cyclinder volume the less the chance that a blue aircraft will be inside the cylinder when the OnTick() check is made & vice-versa. This is a trade-off since you don't want the cylinder to be "too big" because PAC has only limited range/effectiveness.
3. Probability of PAC success -> You can further refine PAC success by adjusting the if (m_random.Next(1, 100) < 81) // guess the chance is 80 times 1:10 = 0.80 line. NB- edited this line in 1st post to make it an abstracted variable.

Jun-30-2012, 03:21
Nice and neat code! You even add external references. Neat! :thumbsup:

Jun-30-2012, 03:45
Help me out here guys becuase I don't fly the 109. I'm using a reference speed of 250mph (402kph) to estimate how long an aircraft will be in the PAC danger zone. eg: An aircraft traveling at 402kph is inside a 1400m diameter circle for 12.52 seconds (at most), which is 12.52/60 chance of triggering a PAC event = 20.9%. Then, using the PAC_success adjustment factor of 0.45, 20.9% * 0.45 = 9.4% chance of hitting a PAC. This is close to my target PAC success rate, but is 402kph a realistic reference speed for a straffing 109?

Jun-30-2012, 05:25
Disregard what I said above then, figured it used physical objects.

As for the speed of a strafing Bf-109. Guess 400KPH is not too far off, if anything it's probably a bit slow.
New pilots seem to putter about over the airfield, turning circles at slow speeds of ~300kph.
While the vets seem to dive in at ~600kph, make a pass and climb back up, then turn and dive down again.

Some comments though:
-Is it possible to display a message only to the player who got hit by it, or to players in the direct vicinity of Hawkinge?
Otherwise all of blue will be spammed by it every X minutes as there is almost always blue activity low over Hawkinge.

-10% sounds very high to me, all your links mention how hard it was to hit a low flying aircraft and how most bombers evaded the cables.
Over the entire BOB there is only a single(?) report that suggests 2 bombers might have been taken out with this system, as those 2 were also hit by AAA.
So it's debatable if the cables were even responsible for taking those 2 planes down.

-Did Germany have anything similar that could be used over Pihen?...because that's regularly visited by Reds aswell. :D

-Real pity CLOD doesn't have collidable cables and the system can't be coded in a realistic way.
Right now it's an arbitrary hit or miss which I personally don't like very much in a sim, and I think lots of guys will complain when their plane gets sawed in half out of the blue.
The base attackers don't last very long anyhow as they are eagerly hunted by pilots and AAA alike, most often they end up damaged or destroyed within minutes.

Jul-03-2012, 01:44
I know it is childish... But I really want this Co pilot in next patch. I like the Uniform. Besides I think it would really bump up the number of people conducting Bomber missions.....that is if they ever get off the ground.