In article zUxgb.704095$uu5.115935@sccrnsc04, "George R. Gonzalez"
wrote:

Off-the-shelf stuff is attractive, at first glance, as it tends to be MUCH
cheaper and lighter than mil-spec equipment.

Not in fighter aircraft applications. COTS is neither cheaper nor lighter.
It's a common mistake made by those who are beguiled by falling
prices on commercial computers, and only look at the initial
purchase price.

But if you look at the problem as the amount of resources you need
to solve the problem, i.e. how much processing you need to do to
get the result you need for the mission, you will discover that mil
packaged electronics, being far more densly packed than commercial
stuff, is lighter and takes up less space, and is more reliable.
If you throw in the cost of airframe mods to fit the bulkier and
heavier COTS, and take into account the extra fuel to lift the heavier
system, and the lower reliability across the airframe life, and the
extra maintenance required for a less reliable system and the extra
spares in the pipeline, suddenly COTS doesn't look as attractive.

In those applications where space and weight are less critical, such
as transport aircraft, or converted transport aircraft, or where
high vibration and temperature extremes and condensing water
are not a factor, then COTS becomes a player.
Trouble is, people look at a successful insertion of COTS in an E-2C
(say) and think it can also be done in an F-16. Not likely.
My 2 cents.

--
Harry Andreas
Engineering raconteur