March 13, 2013 9:30 AM
1. NAGGING NUISANCE WARNINGS
The friction of air seeping into the guts of an aircraft leads to overheating. But the F-35B's sensors are triggering faulty cockpit alarms at temperatures more than 100 degrees Fahrenheit lower than intended. New detectors are being installed.
2. WEIGHED-DOWN WEAPONS DOORS
The doors of the internal weapons bay on the F-35B* are bearing too much of the 5200-pound munition load, leading to testing delays. The warplane can fly with weapons mounted on its wings, but exposed missiles and bombs compromise the airplane's stealth profile.
3. HOT HORIZONTAL TAILS
The tails of all F-35 variants are getting too hot during high-speed flight, scorching the coatings that help them defeat radar. Last September the F-35 program's engineers modified the tails, but the fix delaminated and burned away during flight.
4. BROKEN NOZZLE COVERS
When the F-35B hovers, exhaust is routed through ports in its wings to maintain stability, but the doors covering these nozzles can snap off during flight. Engineers devised an interim fix to close the doors more tightly. Planes delivered after 2014 will have a full repair.
5. PERFORMANCE ANXIETIES
The F-35B may have battlefield shortcomings. The Pentagon has eased its requirement for the craft's tight turns, trimming its sustained g's from 5 to 4.5. Also, testers found excess oxygen in the fuel tanks, increasing risk of explosion if struck by lightning. A redesign is under way.
GLOSSARY: FUELDRAULICS
The F-35B's lift-fan engine uses highly pressurized fuel, rather than hydraulic fluid, to move actuators in the exhaust port. Engineers invented a new word, fueldraulics, to describe the system. The F-35B's original design included shutoff valves that would prevent fires if the F-35B were damaged by enemy weapons, but engineers removed the safety system during a 2008 weight-reduction effort. The result, according to the 2012 Pentagon analysis: "a 25 percent increase in aircraft vulnerability."
* Lockheed Martin is building three F-35 variants: one each for the Marines, the Navy, and the Air Force.
wisconsin recall election april 4 santa monica college wisconsin primary dallas fort worth airport texas tornados seattle seahawks new uniforms
No comments:
Post a Comment