View Full Version : Attack Helicopters on Channel 5
Right Stuff
9th Feb 2004, 06:23
Just noticed there is a programme called 'Ultimate Attack Helicopters' going out on channel 5 monday at 9pm. Should prove to be half decent seeing as it was given critics choice by the Times
Just had a look and its on just before 8pm not 9pm.
MD900 Explorer
10th Feb 2004, 04:15
Quality programme. :ok:
I want a Commanche Now please, and any helo with 3 engines gets my vote. :E
Though i thought the Commanche program was Top Secret (Obviously not now :E )
Digitisation, now what will they think of next? :8
MD
Mr. Lappos, you're needed on stage...
Shawn Coyle
10th Feb 2004, 22:52
Heat seeking missles home on hot metal, not exhaust gases. The shielding provided by the interesting arrangement in the Commanche is supposed to be damn good that way.
(The idea that IR missiles home in on hot gases is a common, but mistaken one - hot metal is what they're looking for)
In answer to your concerns and simply speaking…
1) There is a difference between heat and temperature. A solid object has a higher ‘specific heat constant’ than a gas. As such, the solid has more heat, or energy, in it, for the missile to track. If you look at exhaust through IR, the exhaust vent glows A LOT more than the gas.
2) This is to do with heat transfer. Put simplistically, for a given amount of heat, which has to pass through metal to vent, passing it through a larger duct will ‘spread’ that energy out. Also, the metal duct itself is being likely being cooled by the external airflow, therefore helping the heat to be transferred to the atmosphere.
Hope it helps, if only a bit!
My understanding is that different heat souces on an aircraft emit different wavelengths of IR energy. Older seeker types tracked wavelengths in the 1.5 to 2.5 micrometre band which are created by the hot metal of the jet pipe and are easily decoyed by the sun etc. Newer seekers use the 2.5 to 5 micrometre band created by the exhaust gas plume and also by kinetically heated surfaces giving them a much better all aspect capability.
Hope that helps.