Is a dedicated helicopter-destroyer a feasible idea?

MwRYum said:

Against helicopters, fast movers have very small attack window to make an effective attack run, though would usually be enough to scare off the formation, force them to abort the mission.
Just like forcing bombers to eject their bombs before they reach their targets, it's not always about taking physical kills, make them fail to perform their missions already so.
in the last 20 years USAF have been more than once want to ditch the A-10 but in the end keeping it, because A-10 is fast enough to get to the scene, yet slow enough to effectively engage ground and low-flying targets.
And if you want to engage transport helicopters, UAVs with laser beam-riding Hellfire can do as well, "paint" them when at hover, perfect ambush...of course for the foreseeable future only US can do such thing, China's aviation companies showcased something like that in Zhuhai this month, but UAV still new to PLA overall, adopt UAV as attack platform takes time.

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Eh, semi active laser homing is not very good against something like a helo. Too much glint from the rotors disrupts the return energy.
RBS-70 uses an encrypted laser to send guidance commands to receivers on the tail fins but the operator must keep the target bore sighted for the duration of the engagement, with the flight control computer on the launch unit calculating commands for the missile based on where the operator aims the sights. There is no seeker on the missile itself.

A2A Jets with IRST and IR AA missiles are hell for choppers. Jets flying high leave the choppers almost no option to hide themselves and modern AA missiles (like AIM 9-X or IRIS-T) are not easily fooled by flares. And the choppers moves by far too slow to evade such a missile.

Alienfreak said:

A2A Jets with IRST and IR AA missiles are hell for choppers. Jets flying high leave the choppers almost no option to hide themselves and modern AA missiles (like AIM 9-X or IRIS-T) are not easily fooled by flares. And the choppers moves by far too slow to evade such a missile.

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Not necessarily, jets flying high and fast will miss a helo using nap of the earth techniques and/or terrain masking. If you stay below a certain altitude most IR systems will not see your helo. It's lost in the IR emissions from the ground. We used this to our advantage, always staying below a certain altitude so threat IR systems could not acquire or lock on us.
Flares aren't the only countermeasure to IR missiles, and out of the total population of IR missiles in the world's militaries, flares can still be an effective countermeasure for most. Find out what AN/ALQ-144 is, what we called the "disco light" or it's BAE equivalent. There are additional IR countermeasures besides these two such as AN/AAQ-24 DIRCM and a number of analogous systems.
Finally, military helos cool their engine exhausts and use IR absorbing paints to reduce their IR signature.
Btw, I'm an old military rotorhead. The one thing we feared most wasn't any jet fighter, an IR missile or even a MANPAD, but stumbling across a ZSU-23/4. That thing will ruin your day faster than the best fighter or any IR missile ever will.

There's something I don't understand. With 4/5 generation fighter jets we're concerned about showing a little of the compressor blades. A helicopter with a whacking big rotor with a tip speed of about 1000 km/h must be visible surely?

delft said:

There's something I don't understand. With 4/5 generation fighter jets we're concerned about showing a little of the compressor blades. A helicopter with a whacking big rotor with a tip speed of about 1000 km/h must be visible surely?

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Doppler radars can be adjusted for sensitivity. Adjust the sensitivity to a level necessary to pick out a slow moving helicopter employing nap of the earth tactics and you also pick out fast moving ground vehicles. I learned this from an F-15 pilot who mentioned that if he set the sensitivity of his radar low enough to pick up US Army helos down in the weeds, he would pick up highway traffic too and clutter his radar with junk. Low and slow is the helo pilots friend. I know, I was one of them once.

But radar should still pick up the rotor tips.

I guess that if the aircraft is looking down at the helicopter, and if the heli is flying low enough the rotor tip would be close to the ground anyway. So the difference between radar reflected off the rotor and the radar wave reflected off the ground would not be that much. Whereas aircrafts trying to detect each other usually flies against the clear sky.

Also doppler effect works when there is movement directly towards or away from the radar source, and in the above case most of the rotor motion would be perpendicular to the direction of radar wave travel anyway.

Doppler is entirely dependent on the frequency shift it can measure. A problem encountered with the Sgt. York anti-aircraft gun was the doppler radar used in it didn't acquire helicopters. The doppler shift from the advancing and retreating blades cancelled each other out!
There could be a doppler shift from the rotor system when observed from above, but the frequency of the rotor, it's rpm, will be so low the doppler radar doesn't acquire it.

They shouldn't cancel each other out if they are at different frequencies. The advancing blade would increase the frequency of the return wave and the retreating blade would reduce it, giving two slightly different frequencies range to the one sent out.

The radar would have to be quite sensitive to freq shift because the mechanical turn rate of the rotor is still low by electromagnetic frequency sense.

So the best bet against helicopter is IR sensor and heat-seeker missiles, then?
But what about radiation detection? Radome like those carried by Longbow Apache?