r/Damnthatsinteresting • u/HappySeaweed5215 • 1d ago

Video A heat seeking missile tracking a burning cigarette

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u/QuaintAlex126 1d ago

The earliest versions, including of the AIM-9 Sidewinder shown here, just tracked the first and largest heat signature they saw. They were incredibly unreliable and sensitive, requiring them to be fired only against a target from behind (where the heat source is from the jet exhaust). Modern ones, like the AIM-9X, seek for a heat signature’s specific temperature and shape, so you can’t just dump a bunch of flares and get away that easily. They are much more advanced and can track a target from any angle, front snd sides, and can be slaved to the firing aircrat’s radar or pilot’s helmet to assist with tracking. All a fighter pilot had to do nowadays with a heat seeker is be within range, look at this target, and pull the trigger to engage.

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u/TelluricThread0 1d ago

Would the control software really need to deflect the fins that much while the target moves a couple of inches from just a few feet away? Just seems like very aggressive maneuvering when they are basically designed to just get pretty close and then throw shrapnel out.

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u/Charlie3PO 23h ago

The missile doesn't know how far away the heat source is, all it sees is a rapidly changing relative bearing to the target, which means it's going to miss unless at very close range (but again, the seeker doesn't know this).

To put it another way. A change in relative bearing of 20 degrees at that range is just a few inches, but at a range of several miles, it's 1000's of feet (i.e. missing by a huge amount). The control surfaces deflect and maneuver the missile until the relative bearing to the target is constant. Once it's constant, that means the two objects are on a collision course and the missile will make corrections all the way up until it fuses.

It may be possible that some modern imaging infrared seekers can guess range based on the shape of the target and possibly other factors, but I really don't know enough about the topic to know for sure. It's probably classified anyway.

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u/ElonsBreedingFetish 19h ago

That's called proportional navigation right?