Two unique aircraft now ready to start flight tests are waiting on the ground as crews deal with various glitches. Doc, the B-29 that has been under restoration for years, finally flew last month, but the flight lasted just 15 minutes, shorter than was planned. The flight was cut short after a chip detector device, which monitors the presence of metal debris in the engine, lit up. “The chip detector did its job, but it’s overly sensitive,” said Jim Murphy, Doc’s Friends restoration manager. “The new radial engines on Doc take about 50 hours of flight to break in, and during that time, you’re going to see tiny particles of metal … it’s just the way it is. The biggest particle we found during our inspection was about one-fourth the size of a pinhead.” Murphy said inspections completed since the flight show that all the airplane’s systems and control surfaces are “rock-solid,” and a second flight could happen later this month. Also, the Airlander, the huge lighter-than-air vehicle under development in the UK by Hybrid Air Vehicles, exited its hangar last week, but the first flight, expected on Sunday, was delayed at the last minute.
The company blamed a “technical issue” found during preflight checks for the delay, according to their Twitter account. At the time the glitch was found, not enough daylight remained to complete the required inspections and the test flight. Yesterday, the team said they are “hard at work” on the airship and waiting for a safe “weather window” for another try. The huge aircraft, about 300 feet long, will have a top cruise speed of about 80 knots and can remain aloft for up to two weeks. About 60 percent of the ship’s lift is provided by helium, and the other 40 percent is driven by the ship’s aerodynamic shape and thrust from its rotating engines.