Going to state this now but I will be changing a lot of the HP for helicopters soon and their speed.

Tier 1- will be Helicopter From 1940- 1954 will have an based hp of 1000
Tier 2 Will be Mid to 1955-1975 will have a base of 1500
Tier 3 Will be 1976-20XX which will have a Base of 2000

Recon Helicopter will lose 500hp but be faster to fly.
Attack Helicopter Will stay at base and have a normal flying speed
Transport Helicopter will Get an extra 500hp but fly slower then the rest.

Rotor Hp changes:

Attack Helicopter will have 150HP top || 100HP tail
Transport Helicopter will have 100 top || 100 top
Scout Helicopter will have 100 top || 50 tail