WEP

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War Emergency Power (WEP) is an American term for the throttle setting on some World War II military aircraft engines. For use in emergency situations, it produced more than 100% of the engine's normal rated power for a limited amount of time, often about five minutes. Similar systems used by non-US forces are now often referred to as WEP as well, although they may not have been at the time.

WEP in WWII Aircraft

Maximum normal power would be limited by a mechanical stop, for instance a wire across the throttle lever slot, but a more forceful push would break the wire allowing extra power. Several methods were used to boost engine power by manufacturers, including water injection and methanol-water injection. Some earlier engines simply allowed the throttle to open wider than normal, allowing more air to flow through the intake. All WEP methods result in greater-than-usual stresses on the engine, and correspond to a reduced engine lifetime. For some airplanes, such as the P-51, use of WEP required the plane to be grounded after landing and the engine torn down and inspected for damage before returning to the air.

The German MW50 system required additional piping, as well as a storage tank, increasing the aircraft's overall weight. Like other boost techniques, MW50 was restricted by capacity and engine temperatures and could only be used for a limited time. The GM 1 nitrous oxide injection system, also used by the Luftwaffe, provided extreme power benefits of 25 to 30 percent but required cooling on the ground and added significant weight.

WEP in Aces High II

While some real life WEP systems might have had a finite resource that would limit the duration of use during a flight, the Aces High model universally limits WEP usage via engine tempature. All aircraft with WEP capibility have a duration limit, but can be reused after a "cool down" period allowing WEP to effectively recharge.

WEP duration/Recharge time at MIL power
1.5/0.75 minutes 5/10 minutes 5/15 minutes 10/10 minutes 10/5 minutes 10/20 minutes
Ki-84-la
Ki-43-II
Bf 109E-4
Bf 110C-4b
C.202
F4U-1
F4U-1A
F4U-1C
F4U-1D
F4U-4
F6F-5
FM2
Ki-61-I-KAIc
N1K2-J
P-39Q
P-40E
P-47D-11
P-47D-25
P-47D-40
P-47M
P-47N
P-51B
P-51D
A-20G
B-29
C.205
Hurricane Mk I
Hurricane Mk IIC
Hurricane Mk IID
Lancaster III
Mosquito Mk VI
P-38J
P-38L
Seafire Mk II
Spitfire Mk I
Spitfire Mk V
Spitfire Mk VIII
Spitfire Mk IX
Spitfire Mk XIV
Spitfire Mk XVI
Bf 109F-4
Bf 109G-2
Bf 109G-6
Bf 109G-14
Bf 109K-4
Bf 110G-2
La-5FN
La-7
Me 410
Fw 190D-9
Ta 152H
Fw 190A-5
Fw 190A-8
Fw 190F-8