Navaleye
3rd Sep 2004, 15:19
This cropped up on another board, so I am posting it here for comment.
JSF Program Alters Layout To Meet Performance Parameters (Posted: Wednesday, September 01, 2004)
[Defense Daily, Sept. 1, 2004]
By Lorenzo Cortes
Apart from tackling weight and propulsion issues to meet key performance parameters (KPP) for the short takeoff, vertical landing (STOVL) variant of Lockheed Martin's [LMT] F-35 Joint Strike Fighter (JSF), the JSF program executive officer also said that the program reconfigured the weapons layout for STOVL.
"It was clear to us that with the weight overages that we have seen that we weren't going to get there just by reducing weight in the airplane," Rear Adm. Steven Enewold said yesterday in a interview with Defense Daily. The government/industry steering group for the JSF program thus looked at weight, the propulsion performance, the ways the aircraft would be used in combat and also explored the possibility relaxing some of the requirements for the aircraft.
KPPs for the STOVL JSF include a combat radius of 490 nautical miles and the ability to take off from a 550-foot flight deck for U.S. aircraft and 450 feet for the British version. Earlier this year the Pentagon said it was restructuring the JSF, adding about $5 billion and one year to the development program. The problems were largely associated with weight growth in the STOVL variant of the aircraft.
In June, the Pentagon's Defense Acquisition Board (DAB) signed off on a two-year delay to fielding the planned multirole fighter (Defense Daily, June 29). In addition to the STOVL variant, Lockheed Martin is also building a conventional takeoff and landing (CTOL) aircraft for the Air Force and a carrier variant (CV) for the Navy.
Relaxing requirements in this case center on the way the STOVL version of JSF stores weapons for combat operations. "Specifically, we've asked to move away from a common internal weapons bay and go back to a weapons bay that is smaller," Enewold explained. "We had a unique STOVL weapons bay when we started. It was a smaller weapons bay to carry two 1,000-pound JDAMs (Joint Direct Attack Munitions) and two AMRAAMs (Advanced Medium Range Air-to-Air Missiles) as the KPP load out. Because we thought we could reduce the amount of flight testing and certification and a whole bunch of other good things in the STOVL airplane, we decided to go to a common weapons bay that was common with the conventional and the CV airplanes and we found out we couldn't."
Other modifications include reducing the number of dual-carriage weapons the STOVL could mount externally. "The airplane doesn't look like it has the ability go real fast, real low," Enewold noted. "And so we backed off on the max airspeed of the airplane to match what we think the airplane aerodynamically will do."
The Air Force recently had considered developing an internal configuration of the 25mm cannon for the STOVL JSF. Presently, the program plans to equip STOVL aircraft with a missionized gun on the centerline. In 2002, Lockheed Martin decided to change the cannon for JSF, dropping the longstanding BK 27 27mm gun offered by Alliant Techsystems [ATK] and the Mauser subsidiary of Germany's Rheinmetall and going instead with General Dynamics' [GD] GAU-12 25mm gatling cannon (Defense Daily, Nov. 18, 2002).
"The Air Force is interested in integrating the internal gun into the airplane, predominantly to preserve the signature," Enewold said. "We did some initial looks at it. It looks possible, but not easy. It would add weight and drag to the airplane, we think. So right now we have recommended we not do that in the STOVL design right now."
The steering group, which includes government and industry personnel and is co-chaired by Air Force acquisiton chief Marvin Sambur and his Navy counterpart John Young, approved the STOVL modifications earlier this month.
The next big step for the JSF program is a meeting of the DAB in mid-October. During this meeting, the DAB will ascertain the program's progress.
JSF Program Alters Layout To Meet Performance Parameters (Posted: Wednesday, September 01, 2004)
[Defense Daily, Sept. 1, 2004]
By Lorenzo Cortes
Apart from tackling weight and propulsion issues to meet key performance parameters (KPP) for the short takeoff, vertical landing (STOVL) variant of Lockheed Martin's [LMT] F-35 Joint Strike Fighter (JSF), the JSF program executive officer also said that the program reconfigured the weapons layout for STOVL.
"It was clear to us that with the weight overages that we have seen that we weren't going to get there just by reducing weight in the airplane," Rear Adm. Steven Enewold said yesterday in a interview with Defense Daily. The government/industry steering group for the JSF program thus looked at weight, the propulsion performance, the ways the aircraft would be used in combat and also explored the possibility relaxing some of the requirements for the aircraft.
KPPs for the STOVL JSF include a combat radius of 490 nautical miles and the ability to take off from a 550-foot flight deck for U.S. aircraft and 450 feet for the British version. Earlier this year the Pentagon said it was restructuring the JSF, adding about $5 billion and one year to the development program. The problems were largely associated with weight growth in the STOVL variant of the aircraft.
In June, the Pentagon's Defense Acquisition Board (DAB) signed off on a two-year delay to fielding the planned multirole fighter (Defense Daily, June 29). In addition to the STOVL variant, Lockheed Martin is also building a conventional takeoff and landing (CTOL) aircraft for the Air Force and a carrier variant (CV) for the Navy.
Relaxing requirements in this case center on the way the STOVL version of JSF stores weapons for combat operations. "Specifically, we've asked to move away from a common internal weapons bay and go back to a weapons bay that is smaller," Enewold explained. "We had a unique STOVL weapons bay when we started. It was a smaller weapons bay to carry two 1,000-pound JDAMs (Joint Direct Attack Munitions) and two AMRAAMs (Advanced Medium Range Air-to-Air Missiles) as the KPP load out. Because we thought we could reduce the amount of flight testing and certification and a whole bunch of other good things in the STOVL airplane, we decided to go to a common weapons bay that was common with the conventional and the CV airplanes and we found out we couldn't."
Other modifications include reducing the number of dual-carriage weapons the STOVL could mount externally. "The airplane doesn't look like it has the ability go real fast, real low," Enewold noted. "And so we backed off on the max airspeed of the airplane to match what we think the airplane aerodynamically will do."
The Air Force recently had considered developing an internal configuration of the 25mm cannon for the STOVL JSF. Presently, the program plans to equip STOVL aircraft with a missionized gun on the centerline. In 2002, Lockheed Martin decided to change the cannon for JSF, dropping the longstanding BK 27 27mm gun offered by Alliant Techsystems [ATK] and the Mauser subsidiary of Germany's Rheinmetall and going instead with General Dynamics' [GD] GAU-12 25mm gatling cannon (Defense Daily, Nov. 18, 2002).
"The Air Force is interested in integrating the internal gun into the airplane, predominantly to preserve the signature," Enewold said. "We did some initial looks at it. It looks possible, but not easy. It would add weight and drag to the airplane, we think. So right now we have recommended we not do that in the STOVL design right now."
The steering group, which includes government and industry personnel and is co-chaired by Air Force acquisiton chief Marvin Sambur and his Navy counterpart John Young, approved the STOVL modifications earlier this month.
The next big step for the JSF program is a meeting of the DAB in mid-October. During this meeting, the DAB will ascertain the program's progress.