[jp10]

Might do better checking the combat record of Blowpipes in real life. They were not very effective with a minimum range of .5Km (10 hexes in game) and a MCLOS guidance system.
The Falklands War saw 95 missiles fired by the British. A later report determined that only two kills could be attributed to Blowpipe: A British Harrier attacked by the Argentine Army and an Argentine Aermacchi.

The Blowpipe was found to be particularly ineffective when used to engage a crossing target or to chase a target moving rapidly away from the operator.