Direction of flare ejection?

[Waylander]

As my knowledge about aircrafts is someways limited I always wondered how designers decide into which direction an aircraft ejects it's flares.

For example the US fighters tend to eject them downwards while the B-1B does it upwards. May first idea was that the original mission profile of the B-1B makes it much more likely that an enemy fighter attacks from above.

But that doesn't explain why the Su-27s and MiG-29s also direct them upwards.

I assume Helicopters direct them downwards because of the rotor.

So I would be gratefull if the assembled air force crowd could shed some light onto that.

 

[Scorpion82]

As my knowledge about aircrafts is someways limited I always wondered how designers decide into which direction an aircraft ejects it's flares.

For example the US fighters tend to eject them downwards while the B-1B does it upwards. May first idea was that the original mission profile of the B-1B makes it much more likely that an enemy fighter attacks from above.

But that doesn't explain why the Su-27s and MiG-29s also direct them upwards.

I assume Helicopters direct them downwards because of the rotor.

So I would be gratefull if the assembled air force crowd could shed some light onto that.

Better ask the industries designer crowd. I think it is dependent on two factors 1.) mission profile and 2.) Airframe design. In some cases the locations are likely to be selected on base of the intended mission profile. In other cases the location is more dictated by a viable position on a given airframe.

 

[Waylander]

Thanks for that first insight. At least a fellow German tries to shed some light onto this

Normally our air force forum is active with the most weird discussions one can imagine.
But now...

 

[kato]

There's the line of thought that upward-firing flare ejectors are more useful when the primary opponent are surface-launched heatseeking missiles, especially for lo-lo attack paths.

There's a lot more aircraft, e.g. Rafale, Su-23, OV-1, MiG-27 and Su-24 that all also fire upwards btw.

 

[Waylander]

I would have thought that it is the other way around.

Why are upward firing ones more effective against IR-SAMs? My first thought would be that downward ones are more effective because they are more between the aircraft and the launcher.

 

[Onkel]

I would have thought that it is the other way around.

Why are upward firing ones more effective against IR-SAMs? My first thought would be that downward ones are more effective because they are more between the aircraft and the launcher.

Perhaps because the upward fired flares cross the engine-signatures when going down? May be the onlocked seekers are easier to redirect that way?

 

[Kilo 2-3]

It seems to me that the direction of the flare ejection is contingent on engine placement and the direction the designers anticipated most threats to come from.

For example, the AC-130s operated by the USAF have a distinctive "angel fire" flare ejection pattern. The "wings" of the "angel" form an infrared barrier/distraction between rearward and sideward threats and the exhausts of the turboprops on the AC-130's wings. Meanwhile, the "body" of the angel protects against threats from below and behind.

(I don't know if the guns on the left side of the aircraft produced sufficient thermal signature for a missile to home in on, but the "wing" flares may also distract IR missiles from homing in on any heat the guns produce when fired).

(http://upload.wikimedia.org/wikipedia/commons/4/4f/C-130_Hercules_10.jpg)

On the other hand, fighters like the F-22 eject their flares downwards and slightly to one side, a pattern which presumably provides a flare barrier/line of flares covering and luring IR missiles away from each exhaust.

(http://www.strangemilitary.com/images/content/160978.jpg)

However, this doesn't entirely explain why some aircraft fire their flares upwards. It might be due to differing design philosophies, flare trajectories/ballistics, or as kato said, due to lo-lo mission profiles.

 

[Waylander]

Interestingly helicopters like the CH-53 fire their flares in the same angel pattern a AC-130 does. But they don't have wings with engines on them. So the angel pattern might be especially usefull against MANPADs, unrelated to the type of aircraft. Afterall MANPADs are a much bigger threat to a AC-130 or CH-54 than they are to fighter jets or a bomber like the B-1B.

 

[Bonza]

Interestingly helicopters like the CH-53 fire their flares in the same angel pattern a AC-130 does. But they don't have wings with engines on them. So the angel pattern might be especially usefull against MANPADs, unrelated to the type of aircraft. Afterall MANPADs are a much bigger threat to a AC-130 or CH-54 than they are to fighter jets or a bomber like the B-1B.

Might it also have something to do with the speed of the platform? I'm just guessing, but I wonder if flare patterns could be arranged to allow a longer window for slow moving platforms to get distance on a threat. As I said though I'm really not sure, just speculating.

 

[Kilo 2-3]

Interestingly helicopters like the CH-53 fire their flares in the same angel pattern a AC-130 does. But they don't have wings with engines on them. So the angel pattern might be especially usefull against MANPADs, unrelated to the type of aircraft. Afterall MANPADs are a much bigger threat to a AC-130 or CH-54 than they are to fighter jets or a bomber like the B-1B.

Hmm... That certainly is a possibility, since CH-47s also follow a similar flare ejection pattern. (https://lrc3.monmouth.army.mil/cecomlrc/images/CCS/ch-47flares.jpg).

However, A-10 Warthogs, which face a similar MANPADS threat, eject their flares only in a downward column. This may be due to the placement of the A-10s engines and the fact that the Warthog's rudders and tailplane partially hide the engine's exhausts.

At this point, it seems to me that there isn't really an easy answer to the question, since it's probable numerous factors play a role in determining flare configurations.

On a related note, this article (GTRI Engineers Test New Flare Decoys on Military Aircraft | Georgia Tech Research Institute) alluded to some of the methods and processes used in determining optimal flare patterns.

 

[Toptob]

Hey guys awesome discussion! I hope some of the aeropro's will enlighten us on this.

Until then what I think is they just put the stuff on willy nilly, or wherever there is room. At least on Helicopters, when I see pics of helo's in Afghanistan the flareboxes look like they're just slapped on!

On the trajectory, I imagine that the upwards firing flares make something of a rounded heatprofile that should shield the top and the bottom of the planes heat signature. Furthermore, I can understand that this makes a difference on helo's and transports etc. but on fighters? I figure they twist and turn and loop and dive when they are trying to shake off a heat seaker, so when the flares fire upwards, they will fire downwards when flying inverted. When flares fire to the side they would go both up and down when the aircraft is flying on its side..

I dont know if this helps, maybe I'm stupid or something .

 

[Kilo 2-3]

Until then what I think is they just put the stuff on willy nilly, or wherever there is room. At least on Helicopters, when I see pics of helo's in Afghanistan the flareboxes look like they're just slapped on!

There's actually a degree of truth to that. Based off of what I've heard, a good number of the CH-47s and other medium transport helicopters initially used in Afghanistan and Iraq were not initially fitted with flare countermeasure systems.

However, due to the growing MANPADs threat in these regions, flares were fitted during scheduled overhauls/upgrades or in the field, which would account for the slapdash appearance of the fit.

 

[Wahuuga]

Another possibility might be the doctrine of the particular aircraft in regards to evasion of these threats.

Large aircraft (C-130 etc) cannot change their vector as readily as a smaller aircraft, hence the dispersion of flares directly behind the exhausts.

As far as I know, US aircraft try to change their vector in 3 dimensions, heading, altitude and speed. So if they rapidly bank in one direction, and the flares eject downwards, they would be in the opposite direction to the aircrafts new heading.

Several years ago I read some material which said missiles at the time (90's) could adapt fairly easily to 2 dimensional changes, but adding a 3rd dimension made it much harder for the missile to adapt. Flares ejected upwards would follow roughly the same flight path for a while, making it easier for the missile to choose the flare over the aircraft. Also, most SAM's are very fast as far as I know, once they're close enough to detect between the flares and the plane, they probably cannot maneuverer much.

This is just what make sense to me, I don't really know much about it.