It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Technical problems plague Osprey
JOSEPH NEFF, Staff Writer
The Marines have bet $12 billion and 30 lives on the V-22 Osprey, the revolutionary aircraft that takes off like a helicopter and flies like a plane.
But the Osprey is grounded now, as questions fly about whether the Marines and contractors have pushed the Osprey into production too fast, deleting crucial flight tests and waiving core performance requirements along the way.
Three months ago, the V-22's chronic problems with safety and reliability were thrust into the national spotlight by the crash of yet another Osprey, this time into the woods of Eastern North Carolina.
Four Marines died in the Dec. 11 crash near the Camp Lejeune Marine Base. Of 20 Ospreys built, this was fourth to go down and the second in eight months. The body count now stands at 26 Marines and four civilians.
These are the Osprey's biggest problems, based on a review of crash reports, outside audits, Department of Defense reports, flight manuals, e-mail messages and other documents:
Test pilots have unexpectedly lost control of the Osprey on at least two occasions. One instance of uncontrolled flight, in April 2000, led to a crash in Arizona that killed 19 Marines.
If it loses power, the Osprey cannot land safely in helicopter mode. Conventional helicopters can.
The complex hydraulics system that shifts the engines and rotors from vertical to horizontal is plagued by leaks and requires constant maintenance. A hydraulics failure was the primary cause of the December crash.
Most of the warning signals from the Osprey's diagnostic system -- nearly nine out of 10 -- are false alarms, rendering the warnings all but useless. If a squadron equipped with 12 V-22s had to contend with the current level of false alarms and maintenance problems, five or six craft would be in the repair shop at any one time.
The price per craft has doubled, from $45 million in 1997 to $89.7 million today.
These problems are emerging into public view late in the Osprey's development, but they come as no surprise to those familiar with the craft's history.
For more than a decade, auditors at the Government Accounting Office have warned of the dangers of pushing forward into production before testing was complete.
One correction, it is NOT, dangerous to fly. It simply isn't, and I would expect that half of those problems have been rectified by now.
How about posting some 2007 data, rather than accidents that happened in testing 6yrs ago.
Episode Number: 524
Synopsis: "Osprey, the Marines' New Warplane: Is It Battle-Ready, or Unfit to Fly?" World Report examines the new hybrid aircraft -- half airplane and half helicopter. It's headed to battle in Iraq, but some say it is unsafe and too vulnerable to be deployed.
Also, you're missing out on the advantages it offers- it flies further, faster, and quieter, and at higher altititudes, than the birds it's replacing, with greater payload.
Col. Glenn Walters heads the Marine Corps' aviation plans section in the Pentagon and previously commanded Marine Tiltrotor Operational Test and Evaluation Squadron 22 (VMX-22). He wrote this essay for the North County Times of Escondido, Calif.
Only two V-12 prototypes were built, yet despite its amazing size and lifting power, the design was considered a failure by its manufacturer and Soviet authorities. The V-12 was simply too big and difficult to maneuver to be a practical machine.
First hover 1967 terminated by impact with ground causing severe damage; cause coincidence of primary airframe aeroelastic freq with natural freq of control system, causing uncontrollable vertical oscillations. Second (21142, now at Monino) flown by V.P.Koloshchyenko Aug 1969 to 2255m with payload of 40,204.5kg. NII tests completed and demos at Paris, but abandoned because Mi-26 far superior. ASCC name ‘Homer’.
In June 2003, after a year of extensive testing, program officials held a briefing and flight demonstration to highlight the progress made from mechanical and technical errors revealed by the 2000 crashes. Schultz extolled the extensive testing and provided comprehensive charts of flight-test data.
“We have now solved all the aeromechanical issues. We have solved the logistical issues. … We have solved the engineering issues,” he said.
“The V-22 is much less susceptible to vortex ring state,” Schultz said. “It takes a lot more to get a V-22 into the vortex ring state than any other helicopter.”
The tilt rotor technology even allows for a quicker recovery from this problem by tilting the rotor forward from the helicopter mode and flying out of the vortex ring state, said Lt. Col. Kevin Gross, the chief test pilot from the Marine Corps for the program. To further safeguard against the problem, a device was installed that gives pilots 18 seconds of warning that they might be entering vortex ring state.
The basic aerodynamic mechanisms of the VRS are common to all rotorcraft. However, the probable mechanism that initiates the sudden and potentially catastrophic departure mode in the MV-22 is unique to side-by-side rotor configured aircraft. Qualitatively, this phenomenon is understandable in terms of rotor flow field dynamics, however, other factors may be involved. For example, on the V-22 the proximity of the wing to the rotors means that the airflow state over and above the wing under steep descending flight conditions may have some impact on the rotor flow. Whether this aggravates the already adverse effects in the VRS or otherwise is not yet known because no experiments have been done to study the problem and a completely adequate aerodynamic theory is not yet available to describe the complexities associated with this type of interacting flow.
The V-22 has the potential to enter high rates of descent at high nacelle angles with low airspeed. This condition occurs very rapidly with little to no warning to the pilots. In simulation at 95 degrees nacelle, 39 KCAS, and 0 feet per minute rate of descent (ROD), pulling the thrust control lever (TCL) full aft caused an immediate descent exceeding the 800 feet per minute NATOPS WARNING. If forward TCL is applied at this point, an uncontrolled flight condition is possible. Within 3 seconds, the simulator exhibited in excess of 3,000 fpm ROD.
The consequence of the asymmetrical AoA effect is that if the aircraft is operating near the VRS, the rotor on the side of the yaw direction may enter more deeply into the VRS. By virtue of the lower operating angle of attack on the other rotor, this other rotor will move further away from, or outside of, the VRS conditions. This asymmetrical VRS phenomenon, which is unique to side-by-side rotor configurations, will have the initial resultant effect of inducing a large rolling moment in the yaw direction. If the pilot is able to respond fast enough, the response will probably be a roll control input to counter the initial rolling moment. On the V-22, this requires lateral stick control inputs, increasing collective pitch (power) to the rotor "into the roll" - that is to the rotor operating deeper in the VRS. Because of the high losses associated with rotor operation in the VRS, the excess power available at this rotor is already marginal and so the normal pilot control inputs may be unable to effectively counter the induced rolling moments. Therefore, the roll will continue, and at low altitude the result will be catastrophic.
Furthermore, throughout the maneuver into the VRS, large thrust fluctuations are present on the rotors. Therefore, on the V-22, because of the side-by-side rotor configuration, an additional result of operating in or near to the VRS is out-of-phase fluctuations of thrust on the two rotors. Any unsynchronized rotor thrust fluctuations between the two rotors will always precipitate rolling moments and further compound any asymmetric aerodynamic conditions already induced on the aircraft.