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F-4 Phantom news

Treetop Flyer said:
I'm not an engineer but I'm not sure how taking off with 42,000 pounds of water is supposed to help you go fast, or fly at all.
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If it's anything like automobile systems they would inject the water into the intake air to cool it and increase the efficiency of the combustion cycle.
 
Hopeful Hoya said:
If it's anything like automobile systems they would inject the water into the intake air to cool it and increase the efficiency of the combustion cycle.
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Yeah the harrier uses water injection. It carries up to 500 pounds.

5000 gallons of water weighs over 42,000 pounds. The max takeoff weight of an F-4 is a little over 60,000 pounds.
 
I recall reading a remarkable oral history by a USN F4U Corsair pilot about how the water injection system saved his ass during a low altitude concept is interesting and clearly works.
 
Randy Daytona said:
Anybody of the fast movers want to speculate if the water injection really would get the Rhino up to Mach 3?
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I could write a white paper on the reasons why not. Short(ish) answer:

Not with the current engines. Even if water injection enabled them to develop the necessary power without grenading (unlikely), the aircraft structure and inlet design is all wrong for that speed. Above Mach 2 or so, you'd have shock wave impingement issues, leading to loss of power and probable structural damage to the engine. The aerodynamic heating and loads would cause their share of structural damage too. New engines, ablative materials, structural upgrades, fuel system, ECS, and possibly FCS changes would be needed to even attempt a Mach 3 run. It would honestly be cheaper to build something from the ground up if your goal is a Mach 3 fighter. Or steal a MiG-25 or better yet, a YF-12. The Rhino is designed for maneuverability, taking iron downrange, and landing on the Boat. She can sprint some (depending on loadout) but just isn't built for the incredible demands of flight above Mach 2. I wish it were that easy- we could all be cruising around in sub-orbital flight on a regular basis.

tl;dr version: Water injection yields a small boost in power for transient needs (e.g. takeoff or hovering in the harrier). It's not going to give you twice the speed without a slew of other extreme modifications. It's a fun thought, though.
 
Water injection was for transient high-power situations with old straight-can jets, especially takeoffs. The -52s could only sit at takeoff power for a limited time before they'd have to taxi back and refill the water tanks.
 
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