A-60 and YAL-1 airborne laser versus F-35.

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ABL will be the world's first boost-phase defense against theater ballistic missiles similar to those used against U.S. troops during the Gulf War.

The first shipset of six ABL Infrared Search and Track (IRST) sensors, a derivative of the proven F-14 IRST sensor, were delivered to Boeing by Lockheed Martin Missiles & Fire Control of Orlando, Fla. Four of the six sensors were sent to Wichita, Kan., where Boeing is extensively modifying a 747-400 Freighter into the ABL weapon-system platform. Two sensors were delivered to Boeing in Seattle for integrated testing with missile-tracking software now under development.

The IRST sensors together comprise the ABL's wide-area surveillance subsystem and are to maintain 360-degree surveillance over hundreds of miles from the aircraft while on mission. Once the sensors make an initial detection of a boosting theater ballistic missile, the detection information is sent to the battle management command, control, communication, computers and intelligence (BMC4I) tracker. It will use that information to track the missile's trajectory, and send commands to another surveillance component, the active ranging system (ARS). ARS provides mission personnel with a highly accurate 3D track of its missile target.

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Forum is a bit dead lately so let stir things up.
Imagine you are the pilot of an F-35, tasked with the job to shot down an unknown airborne laser weapon ( based on either A-60 or YAL-1) in your country airspace, you do this alone, no other support for you or them
How will you do it? What tactic
What weapon will you choose to equip your fighter with?
let discuss

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A-60 has no radar or rwr and the targeting control LIDAR only cover forward sector, I don't know the exact range of Lidar but presumably, it is shorter than the distance that APG-81 can track a target as big as A-60.
Tactic: after initial detection, reduce altitude and re-approach from A-60's beam or tail.
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F-35 launch CHAMP (JASSM-ER) from extended range, minimal IR and RF signature of JASSM-ER will hide it from sensors of YAL-1, when close enough, we zap them with EMP beam.

https://www.youtube.com/watch?v=zsQWWQFQWkA

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Laser in atmosphere has very limited range. About 10km for 1MW. That's useless against Meteors and AMRAAMs, or even ASRAAMs and Sidewinders.

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I read a study on using them as a CIWS and for a 10km range, an estimated 1MW was required, but I guess that does focus on sea level engagements where the air is denser. I guess if we multiply by 4 to allow for the change in air density and assume that beam divergence is not a factor then 40km could be possible. But the problem is that with beam divergence the power density at twice the range is quartered, so you need 4x the power for twice the range and an A-60 is no small aircraft. Then you have the problem of one large aircraft vs 4, 6 or 8 smaller fighters who will all be firing missiles, while this laser is taking many seconds to cook its way through one aircraft. I'm also not sure how to interpret those results. 39kW across say 5m^2 isn't that much per square cm, in fact it's less than 1W per cm^2 or less than a laser pointer. Is that really effective at much besides annoying the pilot?

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No difference than engaging AEW or other large aircraft. Both YAL and A-60 are large aircraft with large RCS and potentially large heat signature too due to need of exhaust for cooling their laser assembly.

The laser makes no difference. You will need about 25MW, 3 m mirror assembly to engage aircraft target (25 Kj/sqm hardness) at 250 Km in 1 second engagement. If you desire capability against typical aircraft we have. 100 KW of same laser will do the same but at 1 Minute, meaning you have to aim for a full 1 minute against that target and there could be another one launching missile at you. Smaller mirror assembly will obviously doing less, meaning you have to illuminate the target much longer to obtain the necessary fluence. 1m diameter mirror with 100 KW laser will need 10 Minutes to get enough fluence to do the same job.

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How about 1 m diameter mirror with 2 Mw output such as YAL-1 and A-60
anyway, If it takes 1 minute for 100 kW laser to destroy an aircraft from 250 km, that is a very short amount of time, for comparison, you need a missile constantly moving at Mach 12 to do the same thing, and missile can be evaded but you can't evade a laser beam. Furthermore, that beam will blind the pilot immediately.

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yeah, but that assume the aircraft is not maneuvering and your tracking system and whatever actuator controls the mirror assembly can follow if it maneuver.

and remember. You may face multiple aircrafts and multiple missiles. 1 minute may just not be practical and remember that missile can also come from the side not covered by the laser.

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MiG-31 I'm going by your own image which plots the power on target at specified ranges with specified laser powers. E.g. at 20km range with a 1000kW laser, the power on target is 39kW.

Ah okay, page 54 last para gives specifics. At 5km the spot size is 75cm^2, so at 20km it will be 16x75cm2 = 1200cm^2. With a 100kW laser Figure 28 shows 39kW on that target area at 10,000m altitude and 20km range. So that is 32.5W/cm^2. After many minutes that could probably cook a turkey. To get a useful 1kW/cm^2, you would need approximately 3MW and 20km would hardly keep you safe from MRAAMs or LRAAMs.

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The thing is that. As long as we still using mechanically steered laser. You would want the biggest power and mirror assembly you can get.

We are not yet in era where laser is electronically steered. Maybe then we can actually engage multiple targets and "time share" the laser so the beam will always point at hopefully same spot.

Anyway. I put my calculations in an excel spreadsheet long time ago :

http://www.mediafire.com/file/r25cdq2f6xkokra/LaserCalc.xlsx/file

It based on "Physics of Societal Issue"

You can trade off various parameters namely power, engagement time, target hardness and mirror assembly size. Wavelengths and radiation absorbed by target too.
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For radiation absorbed by target, you can use following chart

http://www.eepw.com.cn/article/201604/289592.htm

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Phased array lasers have been invented but that doesn't solve the problem of atmospheric attenuation or beam divergence.

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You dont solve natural factor. can only have partial remedy. or constrain the operational scenario of the laser.

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[USER="70376"]stealthflanker[/USER] : I think it is very easy for the lens/beam to follow a maneuver aircraft at long distance, because the angular velocity is very small. If the aircraft was moving at 2000 km/h (0.55 km/s) tangent to the optics and the distance is 250 km, the angular velocity is only 0.13 degrees/second

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Okay, that's interesting but can they vary the focal point? Can they put the focal point at any range? The other point which I think stealthflanker is getting at is how to aim your laser at fighters 20+km away. +/- 1 millirad gives +/- 20m left, right, up and down, could you usefully aim at an F-35/F-22 at 100km?

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You can move the focal point by moving the lens, it is similar to how you zoom in and out

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[USER="58228"]mig-31bm[/USER] can't assure that the laser will point at the same area. Remember Ballistic missile can spin as means to resist Laser, letting the area being exposed cool down. Same as Aircraft, and aircraft can do it more freely without fearing of being miss. And no, unless the cockpit is exposed, you wont instantly blind pilot. Thus why you want the engagement time as short as possible. Aside from multiple target engagement. Once laser weapon become common i would expect LWR to be more common to warn pilot that he's being exposed.

Maybe we can take this study to estimate how many aircrafts needed to saturate the laser based on its engagement time.

https://www.scribd.com/document/390262651/Cruise-missile-Defense

We assume the aircraft need to cover 100 Km of range for launch point. mach 0.9. 1 min engagement time. The laser will be saturated by 5 aircrafts. If we have faster aircraft like Mach 1.3, 4 aircrafts will saturate the laser. and so on. If longer ranging missile can be deployed, there could be no aircraft downed and the laser will need to deal with missiles. 1 F-35 can carry or expected to carry Meteor with some 160 km range and may carry as many as 4. and meteor might sustain up to M-3. surviving aircraft can deploy 4 missiles, the laser may have to deal with it and given that M3 missile will cover 150 Km range in just 2 minutes. The laser will be saturated by just 2 missiles, the third might get through.

[USER="71228"]garryA[/USER] I'm already put the spreadsheet. start pulling the numbers. and you seem to have good source too.

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Nice :D

and yes. that's why we have laser safety.

I wish i could improve on providing some form of atmospheric consideration. as the original book Dave Hafemeister's Physics of Societal Issues does not go in depth for it.
and thanks for the book. Now we can expand our target hardness data.

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A naked human eye, but don't pilot visors have inbuilt protection? And I should also point out that using lasers for such purposes would be a breach of the Geneva Convention.

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It might be accidental instead of deliberate.

British however were having a concept for protecting the pilot tho. In their P-125 concept.

https://c1.staticflickr.com/3/2905/14493023699_203e9e4ba5_b.jpg