Re: MMRCA - FX Indiano
Enviado: Qui Fev 02, 2012 11:11 am
AIRCRAFT OPERATIONS FROM RUNWAYS WITH INCLINED RAMPS (SKI-JUMP) by Elijah W. Turner
Fonte: http://www.f-16.net/index.php?name=PNph ... ight=nalls
http://handle.dtic.mil/100.2/ADA237265
This effort was begun in 1982 to investigate the use of inclined ramps (Ski-Jumps) to launch aircraft from short runways as a possible solution to the runway denial problem in Europe. In 1983, Ski-Jump was briefed to the Airbase Survivability Steering Group and "Phase 1 - Analytical Study" was authorized. This report covers work done from January 1982 through July 1986.
ABSTRACT
The use of inclined ramps to launch aircraft from short runways is proposed as a possible solution to the runway denial problem in Europe. Past efforts to launch aircraft in this manner, including a very successful program conducted by the US Navy to launch the T-2C, F-14, and F-18 aircraft, are reviewed.
An analytical study was conducted for the launch of the F-16, F-15, A-10, A-7D and F-4E from inclined ramps. The takeoff ground roll, stabilizer trim setting, landing gear loads and flight trajectory are reported. The F-15 was selected as a candidate aircraft for a USAF flight test program to be patterned after the Navy program and additional studies were performed. Perturbations in center of gravity, thrust, and ramp exit angle were investigated.
A ramp contour was designed for launch of the F-15, F-16, A-7D and A-10 which minimized the length and height of the ramp while maintaining the landing gear loads below 90 percent of their design limit.
BACKGROUND
1.1 Runway Denial Problem
It has been recognized that the bombing of airbases in Europe could effectively close them to fighter operations for several days. Photographs of airbases that were bombed during the Pakastani war indicate that undamaged segments of the runway will not be large enough for conventional fighter aircraft to takeoff or land. Fighter aircraft require an undamaged strip 50 feet wide and from 2000 to 5000 feet long, depending on the aircraft. The probability that a 5000 foot strip will remain undamaged after an attack is near zero. However, the probability that a 1000 foot strip of undamaged pavement can be located somewhere on the airfield is near a certainty. Therefore, a method of launching aircraft with a ground roll under 1000 feet is a possible solution to the runway denial problem.
The operational concept is to have a moderate number of ramps distributed about the airbase at the ends of taxiways and runways. The number should be large enough so that there is a high probability that several will survive. A post attack damage survey would identify the usable ramps and paths for each aircraft to reach the closest usable ramp. A counter attack could be launched as soon as unexploded ordinance and other debris is cleared from the ramps and selected taxiways.
The ramps could also be used to evacuate an air base in a short period of time in the event of an impending attack. The ramps would provide additional launch sites, many of which would be located closer to the aircraft storage area than the operational runway. This would allow a large number of aircraft to be launched in a short period of time. It would also avoid the vulnerability to attack associated with queuing a large number of aircraft on one or two runways.
Ski-Jump Launch
The use of inclined ramps for launching aircraft has been recognized for some time. A NACA report in 1952 proposed the use of an inclined ramp on aircraft carrier decks to improve the takeoff performance of aircraft (Ref. 1). The ramp proposed in the 1952 report had a radius of curvature of 50 feet and a rise of 1.73 feet. Whereas fighter aircraft launched from a flat deck normally sink as much as 9 feet below the deck, analysis indicated that the addition of a ramp would eliminate the altitude loss.
In 1974 a British Commander wrote his masters thesis on launching the Harrier aircraft from inclined ramps (Ref. 2). This report started an effort that resulted in launch test of the Harrier from enclined ramps in 1977.
About the same time, the US Navy was considering a smaller class of aircraft carriers that would not use steam catapults to launch aircraft. This program generated an analytical effort in 1979 followed by a flight test program to launch the T2C, F-14, and F-18 aircraft from inclined ramps. A metal ramp was constructed that could be modified to give ramp exit angles of 3, 6, and 9 degrees. The ramp was 112.1 feet long and 8.58 feet high at the exit when configured for the 9 degree exit angle, measured from the horizontal. A total of 112 launches of the T-2C, 28 of the F-14, and 91 of the F/A-18 were made. The minimum ground roll for the F/A-18 was 385 feet at a gross weight of 32,800 lbs. This ramp effectively reduced the takeoff roll of the F-18 by more than 50 percent.
Flight Dynamics Directorate Effort
Knowledge of the Navy success in ski-jump launch prompted the Flight Dynamics Directorate to propose the same method of launch for ground based aircraft as a possible solution to the runway denial problem in Europe. Studies were performed to estimate the ski-jump performance of a number of Air Force aircraft.
CONCLUSIONS
1. The F-16 and F-15 are candidate aircraft for ski-jump launch of Air Force aircraft. Reductions in the ground roll of more than 50 percent can be expected.
3. A ski-jump ramp with a 9 degree exit angle, contoured so that the F-16, F-15, and A-7D aircraft at combat gross weights can be launched without exceeding 90 percent of design limit landing-gear loads, will be approximately 180 feet long and 14.4 feet high at the exit.
Fonte: http://www.f-16.net/index.php?name=PNph ... ight=nalls
http://handle.dtic.mil/100.2/ADA237265
This effort was begun in 1982 to investigate the use of inclined ramps (Ski-Jumps) to launch aircraft from short runways as a possible solution to the runway denial problem in Europe. In 1983, Ski-Jump was briefed to the Airbase Survivability Steering Group and "Phase 1 - Analytical Study" was authorized. This report covers work done from January 1982 through July 1986.
ABSTRACT
The use of inclined ramps to launch aircraft from short runways is proposed as a possible solution to the runway denial problem in Europe. Past efforts to launch aircraft in this manner, including a very successful program conducted by the US Navy to launch the T-2C, F-14, and F-18 aircraft, are reviewed.
An analytical study was conducted for the launch of the F-16, F-15, A-10, A-7D and F-4E from inclined ramps. The takeoff ground roll, stabilizer trim setting, landing gear loads and flight trajectory are reported. The F-15 was selected as a candidate aircraft for a USAF flight test program to be patterned after the Navy program and additional studies were performed. Perturbations in center of gravity, thrust, and ramp exit angle were investigated.
A ramp contour was designed for launch of the F-15, F-16, A-7D and A-10 which minimized the length and height of the ramp while maintaining the landing gear loads below 90 percent of their design limit.
BACKGROUND
1.1 Runway Denial Problem
It has been recognized that the bombing of airbases in Europe could effectively close them to fighter operations for several days. Photographs of airbases that were bombed during the Pakastani war indicate that undamaged segments of the runway will not be large enough for conventional fighter aircraft to takeoff or land. Fighter aircraft require an undamaged strip 50 feet wide and from 2000 to 5000 feet long, depending on the aircraft. The probability that a 5000 foot strip will remain undamaged after an attack is near zero. However, the probability that a 1000 foot strip of undamaged pavement can be located somewhere on the airfield is near a certainty. Therefore, a method of launching aircraft with a ground roll under 1000 feet is a possible solution to the runway denial problem.
The operational concept is to have a moderate number of ramps distributed about the airbase at the ends of taxiways and runways. The number should be large enough so that there is a high probability that several will survive. A post attack damage survey would identify the usable ramps and paths for each aircraft to reach the closest usable ramp. A counter attack could be launched as soon as unexploded ordinance and other debris is cleared from the ramps and selected taxiways.
The ramps could also be used to evacuate an air base in a short period of time in the event of an impending attack. The ramps would provide additional launch sites, many of which would be located closer to the aircraft storage area than the operational runway. This would allow a large number of aircraft to be launched in a short period of time. It would also avoid the vulnerability to attack associated with queuing a large number of aircraft on one or two runways.
Ski-Jump Launch
The use of inclined ramps for launching aircraft has been recognized for some time. A NACA report in 1952 proposed the use of an inclined ramp on aircraft carrier decks to improve the takeoff performance of aircraft (Ref. 1). The ramp proposed in the 1952 report had a radius of curvature of 50 feet and a rise of 1.73 feet. Whereas fighter aircraft launched from a flat deck normally sink as much as 9 feet below the deck, analysis indicated that the addition of a ramp would eliminate the altitude loss.
In 1974 a British Commander wrote his masters thesis on launching the Harrier aircraft from inclined ramps (Ref. 2). This report started an effort that resulted in launch test of the Harrier from enclined ramps in 1977.
About the same time, the US Navy was considering a smaller class of aircraft carriers that would not use steam catapults to launch aircraft. This program generated an analytical effort in 1979 followed by a flight test program to launch the T2C, F-14, and F-18 aircraft from inclined ramps. A metal ramp was constructed that could be modified to give ramp exit angles of 3, 6, and 9 degrees. The ramp was 112.1 feet long and 8.58 feet high at the exit when configured for the 9 degree exit angle, measured from the horizontal. A total of 112 launches of the T-2C, 28 of the F-14, and 91 of the F/A-18 were made. The minimum ground roll for the F/A-18 was 385 feet at a gross weight of 32,800 lbs. This ramp effectively reduced the takeoff roll of the F-18 by more than 50 percent.
Flight Dynamics Directorate Effort
Knowledge of the Navy success in ski-jump launch prompted the Flight Dynamics Directorate to propose the same method of launch for ground based aircraft as a possible solution to the runway denial problem in Europe. Studies were performed to estimate the ski-jump performance of a number of Air Force aircraft.
CONCLUSIONS
1. The F-16 and F-15 are candidate aircraft for ski-jump launch of Air Force aircraft. Reductions in the ground roll of more than 50 percent can be expected.
3. A ski-jump ramp with a 9 degree exit angle, contoured so that the F-16, F-15, and A-7D aircraft at combat gross weights can be launched without exceeding 90 percent of design limit landing-gear loads, will be approximately 180 feet long and 14.4 feet high at the exit.
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