War emergency power
War emergency power (WEP) is a
WEP in World War II aircraft
Maximum normal power would be limited by a mechanical stop, for instance a wire across the throttle lever slot. A more forceful push would break the wire, allowing extra power. In normal service, the
British and Commonwealth aircraft could increase power by increasing the supercharger boost pressure.[5] This modification was common by the summer of 1940, with the widespread availability of 100 octane fuel. Raising supercharger boost pressure from 6 to 12 psi (41 to 83 kPa)[5] increased the Merlin III engine rating to 1,310 hp (980 kW), an increase of over 250 horsepower (190 kW). Pilots had to log the use of emergency boost and were advised not to use it for more than 5 minutes continuously.
The German
Modern times
MiG-21
This section needs additional citations for verification. (May 2024) |
Perhaps the most dramatic WEP feature was found in the
The MiG-21bis received the upgraded Tumansky R-25 engine, which retained the standard 9,400 / 14,600 lbf (42 / 65 kN) normal and afterburner power settings of earlier R-13 powerplants, but with emergency thrust boost from an overspeed to 106% and increased afterburner fuel from a second afterburner fuel pump.[7] Use of this boost feature provided 21,900 lbf (97.4 kN) of thrust for 2 minutes maximum in wartime. It gave the MiG-21bis slightly better than 1:1 thrust-to-weight ratio and a climb rate of 50,000 ft/min (254 m/s), equalling F-16 capabilities in a dogfight.
In air combat practice with the MiG-21bis, use of WEP thrust was limited to one minute, to reduce the impact on the engine 800 hours time between overhaul, since every second of WEP was equivalent to several minutes of running without it. When WEP was selected, the R-25 produced a 16 feet (5 m) long blowtorch exhaust - the six or seven brightly glowing rhomboid "shock diamonds" visible inside the flames gave the emergency-power setting its "diamond regime" name.
F-15C
The Vmax switch on the
WEP in surface vehicles
Some modern military surface vehicles also employ WEP features. The US Marine Corps Expeditionary Fighting Vehicle (cancelled in 2011) sported a 12-cylinder 1,200 bhp (890 kW) diesel engine developed by the German company MTU. When the EFV is swimming the powerplant can be boosted to 2,700 hp (2,000 kW) via the use of open circuit seawater-cooling.[10] Such extreme war power setting allows the MTU engine to drive four massive water-jet exhausts which propel the surface-effect riding EFV vehicle at sea speeds reaching 35 knots (65 km/h).
Although the EFV prototypes demonstrated revolutionary performance on water and land, the reliability of their extremely boosted powerplants never met stringent military standards and the vehicle failed to enter Marine Corps service.
Boost systems
- Water injection
- MW50(German, methanol/water mixture)
- GM 1 (German, nitrous oxideinjection)
- Forsazh (Russian)
- Propane injection
See also
- Index of aviation articles
- List of aviation, avionics, aerospace and aeronautical abbreviations
- Battleshort
- Afterburner
- Supercruise
- Flank speed
- Wartime reserve mode
References
- ^ "Flight of the Mustang". Archived from the original on December 8, 2004. Retrieved 2006-03-28.
- ^ a b "Vought F4U Corsair". Historic Aircraft.
- ^ Baugher, Joe (1999-09-06). "North American P-51H Mustang". North American P-51 Mustang. Archived from the original on August 29, 2005. Retrieved 2006-03-28.
- ^ a b AAF Manual 51-127-3, Pilot Training Manual for the P-51 Mustang, USAAF, August 1945, p.14.
- ^ a b "Hurricane Mk1 Performance". WWII Aircraft Performance. Retrieved 9 November 2015.
- ^ a b "The Daimler-Benz DB 605". The Luftwaffe Page. Archived from the original on February 2, 2006. Retrieved 2006-03-04.
- ^ http://www.leteckemotory.cz/motory/r-25/
- ^ Themely, Andrea. "Fighter Pilot Breaks Down Every Button in an F-15C Cockpit". Ars Technica. Retrieved 5 December 2022.
Out of all of these controls here, there's actually one that we are prohibited from using and that is the VMAX switch down here on the left console. So it is actually safety wired shut and it is guarded closed, and it's a switch that we're not actually allowed to use. But if you were to use it, if you were to rip that safety wire off and unguard it, and turn that on, what it's gonna do is allow the engine to burn 22 degrees hotter, and it gives you about 2% more revolutions per minute. So it really just gives you a little bit of extra thrust if you need it in a combat situation.
- ^ Newdick, Thomas (Feb 26, 2024). "Just How Fast Is The F-15EX Really?". The War Zone. Retrieved 31 May 2024.
- ^ https://apps.dtic.mil/sti/tr/pdf/ADA524830.pdf