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06.30.05

ER-2 Capabilities and Performance

Summary

The Lockheed ER-2 was developed for the National Aeronautics and Space Administration (NASA), to serve as a high altitude scientific research aircraft. The ER-2 designation was first applied to NASA's version of the U-2C model. NASA has since acquired and used the U2-R or TR-1 model, but has retained the ER-2 descriptor. The newest ER2 (U2-R) was built and delivered in 1989 and represents one of NASA's youngest aircraft. The ER-2 differs from the U.S. Air Force's U-2 in the lack of defensive systems, absence of classified electronics, completely different electrical wiring to support NASA sensors, and, of course, a different paint scheme. Both NASA ER2s were re-engined with new General Electric F-118-101 engines in the late 90's at the same time the U2 fleet was re-engined, providing much-improved range, endurance, altitude, and reliability.

The ER-2 is an extremely versatile aircraft well suited to multiple mission tasks. The ER-2 is thirty percent larger than the original U-2 with a twenty foot longer wingspan and a considerably increased payload over the older airframe. The aircraft has four large pressurized experiment compartments and a high capacity AC/DC electrical system, permitting a variety of payloads to be carried on a single mission. The modular design of the aircraft permits rapid installation or removal of payloads to meet changing mission requirements. The ER-2 has a range beyond 6,000 nautical miles; is capable of flight duration well in excess of 10 hours, and can operate at altitudes above 70,000 feet (21.3 km) if required. Range and duration are normally restricted due to pilot duty time limitations.

Scientific instruments flown aboard the ER-2 can be mounted in various payload areas. On a single flight, the ER-2 can carry over one ton of instruments to altitudes above 65,000 feet and outside 95% of the Earth's atmosphere.

Specifications (per USAF-releasable data)

Crew: One Pilot
Length: 62 feet, 1 inch
Wingspan: 103 feet, 4 inches
Engine: One General Electric F-118-101 engine
Altitude: above 70,000 feet
Range: over 6000 nautical miles, subject to pilot duty time limitations
Duration: over 10 hours
Cruise Speed: ~400 knots above 65,000 feet altitude (~210 meters/sec)

Payload

Nose: 600 lbs
Q-bay: 750 lbs
Wing Pods: 1360 lb


Rate of Climb and Maximum Altitude

A typical ER-2 sortie begins with a short ground roll followed by a very high rate of climb at a high climb angle. Depending upon takeoff gross weight and planned mission endurance, the aircraft will reach the intermediate cruise altitude of 18 km (60,000 feet) within thirty to forty-five minutes of launch. At this point the cruise climb is initiated. While holding mach number and engine exhaust temperature constant, the aircraft will steadily climb as fuel is burned off. The cruise climb segment of a typical mission will begin no lower than 18 km (60,000 feet), and can continue to over 21 km (70,000 feet), depending on the aircraft's total weight and configuration.

During the flight, altitude excursions can also be caused by changes in outside air temperature; these variations can be from 50 to 100 meters. Descent is generally initiated a half hour prior to landing.

For special payload operations, flights below 60,000 feet can be performed. However, aircraft and engine performance suffer at these low altitudes, pilot workload increases, and air traffic control concerns multiply. Any request to operate at altitudes other than the nominal must be coordinated well in advance of actual operations.

Aircraft Speed

At cruise altitude the Mach number is held constant at M = 0.715. This is equivalent to a true airspeed of approximately 210 m/sec (410 knots).

At lower altitudes, as on final approach for landing, the true airspeed is much lower; 90 - 100 knots.

Aircraft Range and Endurance

A normal eight hour mission will cover a range of 3000 nautical miles, and yield approximately seven hours of high altitude operations. Missions of 10 hours or more are possible, but impose additional risks to the pilot, aircraft, and sensors. Every effort is made to minimize these risks, and extended missions require additional justification. Missions of this length will also strongly affect the available crew resources for ensuing flight operations.

Stability

At its cruising altitude, the ER-2 is a very stable aircraft. The automatic flight control system augments stability in the yaw, pitch, and roll axes. Pitch and roll excursions are typically less than one degree over a flight line.

ER-2 navigation recorder flight data graph.

Turn Radius at Altitude

Bank Angle  Turn Diameter
degrees Naut. Mi. km
5 56.2 104
10 27.9 52
15 18.3 34
20 13.5 25
22
(standard)
12.2 23

At constant Mach number, banking the wings to turn the aircraft inevitably imposes a loss of lift, and thus altitude. This altitude loss can be up to a thousand feet, which is gradually recovered over the next straight-and-level flight leg.