With the Leviathans Update introducing Imaging Infrared (IIR) anti-aircraft missiles in the form of IRIS-T and AIM-9X it is time for the Gaijin to revert the ahistorical nerfs that they made to BOL countermeasures and restore their effectiveness to at least pre-nerf levels.
- Yes
- No
Wait what on earth are BOL countermeasures?
BOL is a type of countermeasures (chaff / flare) dispenser which fits into the rear of a missile launch rail, allowing a large number of countermeasures to be carried in space that would otherwise go unused. The countermeasures are stored as flat packets on a belt inside the launcher, allowing 160 countermeasures to be carried per launcher. Imagine a loaf of sliced bread on a conveyor belt and each time the belt moves one slice falls off the end, that’s basically how BOL works, only with chaff / IR decoys instead of slices of bread.
BOL countermeasures are used on many aircraft in game, including the Harrier, Tornado, Gripen, Eurofighter, and some versions of the F-18.
So what did Gaijin do to them?
BOL was originally introduced with the same performance as normal countermeasures but in update 25.01.2024 Gaijin massively reduced the effectiveness of BOL countermeasures (seemingly prompted by how well the Gripen was performing at the time). This graph shows the effectiveness and duration of the different types of flares in game. It can be seen that the luminosity (how attractive the countermeasure is to missiles) of the BOL countermeasures was reduced by ~40% compared to standard countermeasures and the time they remain effective for after being fired was reduced by ~60%. BOL chaff was hit even worse, with it’s RCS reduced by a whopping 75% compared to normal chaff.
This double whammy of nerfs has massively reduced the effectiveness of BOL countermeasures, and made aircraft which rely on them for the bulk of their countermeasures (for example the Tornado F.3) increasingly hard to play as newer and newer missiles have been added over the last year.
What makes the nerf ahistorical?
Gaijin’s stated reason for making this change is that BOL countermeasures are physically lighter than most other countermeasures, so should be less effective. While it is true that BOL countermeasures are lighter than traditional countermeasures it is not at all correct to conclude that this makes them less effective. Let’s look at this in more detail.
BOL Chaff
BOL chaff consists of a lightweight plastic frame with packets of chaff within it, the frame is ejected from the BOL launcher, and the airflow then breaks the packets open dispersing the chaff.
In game standard chaff is based on the Russian 26 mm chaff cartridge, which has a mass of 55 g, meanwhile the BOL packet has a total mass of 45 g.
Spoiler
Chemring BOL Datasheet:
Chemring 26 mm Chaff datasheet (Fit-Form-Function replacement for out of production PPR-26 chaff cartridges)
So it is true that a BOL chaff packet is lighter than a normal chaff cartridge, however the difference in mass is only 18%, which clearly does not justify a 75% decrease in RCS. However this is simply comparing the total mass of the BOL packet and the chaff cartridge, lets see what happens if we compare the actual volume of chaff within each.
A BOL chaff packet is 71.8 mm x 85.5 mm x 11.3 mm, pixel measuring that gives us a block of chaff that is roughly 60.0 x 68.2 x 10.0 mm or 40,920 mm3. By comparison a 26 mm chaff cartridge is 26 mm in diameter and 86 mm long. If we are very generous and assume that 10 mm of that total length is lost to the base plate, the end cap (that stops chaff falling out), and other stuff like the plunger that forces the chaff out then we get a maximum possible chaff cylinder of 26 mm x 76 mm, which equates to 40,350 mm3 of chaff (and that is a generous estimate).
So we can see that a BOL chaff packet likely contains no less chaff than a typical chaff cartridge.
Spoiler
That’s not all though. Due to it’s placement inside a missile launch rail BOL chaff is typically carried in the wing (where traditional chaff is carried in fuselage dispensers on most aircraft). In their brochure SAAB explicitly note that being mounted on the wing, significantly increases BOL’s RCS compared to traditional chaff, due to the vortices near the wing tip helping the chaff rapidly bloom. In addition air scoops on the back of the the launcher further increase this effect. So not only is BOL chaff no smaller than conventional chaff it is more effective too!
Spoiler
BOL IR
BOL IR is a tad more complicated than the chaff. BOL IR is not actually a flare in the traditional sense it is a pyrophoric spatial IR decoy. A pyrophoric material is sealed within a plastic packet, when the packet is ejected it breaks apart and the material is released into a cloud, much like chaff. The material then reacts with the air, rapidly oxidising and producing an intense cloud of infrared radiation. It should be noted that BOL IR is near invisible to the naked eye as nearly all of its energy is concentrated in the IR spectrum (unlike conventional flares which waste some energy producing visible light).
This mechanism actually makes BOL IR more effective than conventional flares against IIR missiles. The Spatial nature of the decoy makes it appear as a similar in size to the aircraft, rather than as a single hot point that the seeker can easily identify and ignore. Here is an example of BOL IR viewed through a thermal camera:
In addition spatial decoys like BOL IR can entirely block an IIR missile’s view of a target in the rear aspect, allowing the target to escape while the missile is blinded. This effect can be seen in these images:
Conclusion
Gaijin’s nerf to BOL countermeasures is not historically accurate and for over a year this change has had a major detrimental impact on a wide range of aircraft which rely primarily on BOL for self-defence. With the arrival of missiles featuring IIR seekers, which BOL IR was specifically designed to defeat, it is time for Gaijin to reverse the nerf they made to BOL. In real life BOL countermeasures are just as effective, if not more so, than traditional countermeasures, so should be returned to being at least as good as normal countermeasures in game.
