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This article and video discuss the effects of Chaff against the APQ-120. If you are not new to DCS, you probably know that the countermeasures in the game are quite poorly represented, behaving more like a random dice roll than actual physical objects with properties and characteristics apt to divert the attention of hostile missiles. Hopefully, at some point, the countermeasures in DCS, Chaff especially, will be overhauled and improved.
What are chaff?
Chaff are one of the most primitive countermeasures, even pre-dating the Second World War. Their task is to disrupt radars by creating clouds representing false contacts or saturating the observing radars.
“When activated, “chaffing” would send thousands of tiny metallic fibres – 60 per cent glass, 40 per cent aluminium, and the thickness of a human hair – into the air. They were designed to reflect and interfere with enemy radar signals, confusing both the systems and their operations.”
The next quote is from Bruce Gordon’s “The Spirit of Attack: Fighter Pilot Stories”, and discusses a curious event that occurred during a training exercise between his F-106 Delta Dart and F-104 Starfighters.
“We had started the inbound attack covering the F-101’s and I was looking hard for any radar targets above and ahead of us, where the F-104’s would be coming from. I saw a target, quickly locked on it, lit my afterburner and attacked. In less than ten seconds I noticed that I was closing on the target at about 700 knots — which was my own airspeed! My target was not moving — it must be chaff! Impossible! F-104’s don’t carry chaff! By the time I admitted to myself that I had been suckered off on a bundle of chaff, the air battle had moved on and I had missed the fight.”
Chaff in DCS
As mentioned, Chaff in DCS do not behave realistically. They are very short-lived elements incapable of saturating radars. Nevertheless, Heatblur has implemented what they could, and the effect on the radar screen is very interesting.
In this scenario, the F-4E is sitting as a spectator of a fight between a Tomcat armed with AIM-7s versus a Mirage 2000. The latter is not defending, just flying around and popping Chaff occasionally. Tacview helps to better understand the situation.
The chaff expelled by the Mirage whilst trying to shake the Sparrows are clearly visible both in Long and Short pulse. However, they dissipate after a few seconds.
Locking Chaff
What if the WSO tries to lock the chaff expelled by the Mirage? The video above clearly shows how the WSO can lock the Chaff, but a glance at the closure indication should immediately reveal that something is off. However, attempting to capture the target again often results in a solid and good lockon because the Chaff in DCS dissipates so quickly. Moreover, depending on the aspect and heading, the disappearing Chaff will inadvertently push the radar to lock on the actual target’s echo.
Conclusions
As we have seen, the Chaff effects are clearly displayed, but they dissipate after a few short seconds. The situation is quite different from reality, as Bruce Gordon’s passage clearly explains. In DCS, in fact, his target would have vanished almost immediately, revealing the mise-en-scène even before his training and experience made him notice the closure rate.
I hope I will have to update this article and video soon as new countermeasure mechanics are implemented. Before leaving, here is how the Starfighters managed to trick Bruce. I highly recommend his book and YouTube channel. Check them out!
“I waited for the F-104 pilots to tell their stories, and none of them mentioned chaff. I could stand it no longer, so I stood up and asked: “OK, which one of you dropped CHAFF”? They all broke out laughing! One of them put a couple of bundles of chaff inside his speed brakes. He kept his speed brakes closed until the moment he thought we’d be in radar range, then briefly popped his speed brakes open and closed. The chaff bundles broke open as they hit the high-speed air, making a cloud of metal-coated fiber needles which I had locked onto. A simple trick, but it worked.”
FlyAndWire 