Towed Decoys

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steve2267

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Unread post10 Jun 2019, 16:07

<deleted> for now...
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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marauder2048

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Unread post12 Jun 2019, 21:57

wrightwing wrote:Towed decoys are far enough away, that a large warhead isn't going to be a threat. The decoys are generating EA waveforms, to keep seekers spoofed. Lastly, by the time the missile realizes that it's a decoy, it's geometries are not going to be close to ideal, to re-engage the aircraft.


Normally, the bigger warhead is accompanied by some trajectory shaping and late seeker turn-on.
The average miss-distance goes up which you compensate for with a large warhead.

Keep in mind that if the platform needs to maneuver aggressively, the tow line length isn't all that great
and there's a real tradeoff between tow line length and decoy power though the latter isn't so prominent
with fiber optics and solid state amplifiers.

And then there are some deliberate proximity fuze designs that are intended to be less sensitive to the returns
from the decoy on the assumption that say in a tail chase, the missile's trajectory will bring it beyond the
decoy and on to the platform.

But I agree that there is no generalized counter-countermeasure that's going to work without
some annoying tradeoffs or be cheap enough to implement widely.
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wrightwing

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Unread post12 Jun 2019, 22:25

https://i2.wp.com/theaviationist.com/wp ... ight-1.jpg

At that distance, the decoy should be outside of a lethal blast radius, and the incoming missile likely won't have the energy to change course (assuming, the ruse is recognized.)
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marauder2048

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Unread post12 Jun 2019, 23:37

wrightwing wrote:https://i2.wp.com/theaviationist.com/wp-content/uploads/2012/04/decoy-highlight-1.jpg

At that distance, the decoy should be outside of a lethal blast radius, and the incoming missile likely won't have the energy to change course (assuming, the ruse is recognized.)


Do you mean that the platform would be outside of the lethal radius with say a missile coming in broadside?

Some of the S-300 missile variants have lethal radii in the 100 ft range.
That is uncomfortably close for some of the shorter tow line lengths.
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Dragon029

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Unread post14 Jun 2019, 00:53

marauder2048 wrote:Keep in mind that if the platform needs to maneuver aggressively, the tow line length isn't all that great
and there's a real tradeoff between tow line length and decoy power though the latter isn't so prominent
with fiber optics and solid state amplifiers.


On that, it's my understanding that towed decoys (at least those using fiber optic cables) are powered exclusively by a battery - I saw online (accuracy unknown) that the ALE-55 for example has an 8 hour stand-by time. If systems like BriteCloud (which are smaller, but probably not by an order of magnitude) have a battery life of around 10 seconds (of transmitting), I wonder how long something like the ALE-70 can transmit for until it runs out of power.

Ultimately it'll be able to save power by being able to offload most of its processing to the ASQ-239 computers on the jet, plus it doesn't need to be as powerful as an ALE-50, ALE-55, etc due to the stealth of the F-35, plus towed decoys are only emitting when they need to / when the ASQ-239 tells them, plus the F-35 can carry 4 of these decoys to use one-after-the-other, but I still wonder if we're talking (eg) 20 seconds of transmitting time, or multiple minutes, or whether the ALE-70 has some method of getting power from the F-35 (conductive material between the fiber optic and kevlar braiding for example).
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wrightwing

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Unread post14 Jun 2019, 02:09

marauder2048 wrote:
wrightwing wrote:https://i2.wp.com/theaviationist.com/wp-content/uploads/2012/04/decoy-highlight-1.jpg

At that distance, the decoy should be outside of a lethal blast radius, and the incoming missile likely won't have the energy to change course (assuming, the ruse is recognized.)


Do you mean that the platform would be outside of the lethal radius with say a missile coming in broadside?

Some of the S-300 missile variants have lethal radii in the 100 ft range.
That is uncomfortably close for some of the shorter tow line lengths.


If you look at how far that decoy is behind the Typhoon, you'll see it's well over 100' (and possibly >100m.)
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marauder2048

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Unread post14 Jun 2019, 03:50

The FOTDs I'm familiar with are externally powered; the TWT based amplifiers have 5000 V power lines.
You're right that MMICs, operating at much lower voltages, could be battery powered and that might
help reduce the complexity of the tow line.
Attachments
fotd-towline.png
https://www.nrl.navy.mil/content_images/Electronics_2010.pdf
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marauder2048

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Unread post14 Jun 2019, 04:13

wrightwing wrote:
marauder2048 wrote:
wrightwing wrote:https://i2.wp.com/theaviationist.com/wp-content/uploads/2012/04/decoy-highlight-1.jpg

At that distance, the decoy should be outside of a lethal blast radius, and the incoming missile likely won't have the energy to change course (assuming, the ruse is recognized.)


Do you mean that the platform would be outside of the lethal radius with say a missile coming in broadside?

Some of the S-300 missile variants have lethal radii in the 100 ft range.
That is uncomfortably close for some of the shorter tow line lengths.


If you look at how far that decoy is behind the Typhoon, you'll see it's well over 100' (and possibly >100m.)


From memory, for aggressive maneuvering tow line lengths are around 150 feet but the rule of thumb
is that the tow line length needs to be at least twice the lethal radius of the missile's warhead.
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wrightwing

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Unread post14 Jun 2019, 07:57

marauder2048 wrote:

From memory, for aggressive maneuvering tow line lengths are around 150 feet but the rule of thumb
is that the tow line length needs to be at least twice the lethal radius of the missile's warhead.

That decoy is more than 3 plane lengths behind the Typhoon, which is 52.4' long.
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marauder2048

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Unread post14 Jun 2019, 09:46

[YouTube][/YouTube]
wrightwing wrote:
marauder2048 wrote:

From memory, for aggressive maneuvering tow line lengths are around 150 feet but the rule of thumb
is that the tow line length needs to be at least twice the lethal radius of the missile's warhead.

That decoy is more than 3 plane lengths behind the Typhoon, which is 52.4' long.



Could be the braking point. But they also look like that when they are still untethering.

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aussiebloke

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Unread post14 Jun 2019, 10:28

In 2003 over Iraq Dan Hampton repeatedly deployed towed arrays. At one point in the book Viper Pilot he gives a length for the tow line:

Flipping the Viper on its back, I deployed one of my towed decoys. This little thing would stream out 300 feet behind me on a cable and generate a nice fat signal for missiles to track instead of my jet.


From the section of the book dated April 7, 2003 http://abramtsevo.msk.ru/rlib/utf8/480601.html

Presumably this decoy was the ALE-50.
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marauder2048

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Unread post15 Jun 2019, 22:06

aussiebloke wrote:In 2003 over Iraq Dan Hampton repeatedly deployed towed arrays. At one point in the book Viper Pilot he gives a length for the tow line:

Flipping the Viper on its back, I deployed one of my towed decoys. This little thing would stream out 300 feet behind me on a cable and generate a nice fat signal for missiles to track instead of my jet.


From the section of the book dated April 7, 2003 http://abramtsevo.msk.ru/rlib/utf8/480601.html

Presumably this decoy was the ALE-50.



Given that they can actively brake the tow line length based on threat how is this relevant?
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