Douglas A/B-26 Invader

Flying the A-26 Invader














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"Starting the two engines is easy when they're cool.

Standing behind them is not recommended, unless you want oil-speckled clothes. Starting warm or hot engines is a bit more challenging, but checklist procedures work.

Next we have to wait for the 39 U.S. gallons (148 litres) of oil in each engine to warm up before we can apply any significant power-big radial engines refuse to be rushed.

Nose-wheel steering is not available, but once we’re rolling directional control with the throttles and gentle braking is all that's needed. The run-up is pretty standard; both engines are checked simultaneously to avoid undue stress on the nose gear.

With the run-up complete the pre-takeoff check is performed. At the top of the list is "CANOPY - Closed and Locked". There are two locking handles-fail to properly secure the canopy, and just after liftoff one or both halves will fling open with a heart-stopping "thump" followed by lots of noise, cold air and your maps! They can't be closed in flight, so it's worth the extra few seconds to confirm that both sides are actually locked.

With checks complete, transmit on the radio, ensure the approach and runway are free of conflicting traffic, roll onto the runway and smoothly advance the throttles. The Low supercharger gives us an impressive 52 inches of manifold pressure at 2,700 rpm; acceleration is brisk and necessary - even with takeoff flaps, those laminar flow wings require a lot of speed to get us airborne. Apply light backpressure at 85 K to raise the nose wheel, and the aircraft will fly off at 95 K to 110K, depending on the load carried.

We're still well below minimum control speed (vmc) of 122 K (140 K fully loaded) in the event of an engine failure. This is no time to relax. Landing gears up, flaps up at 120 K, METO (Maximum Except TakeOff) power (42 inches, 2,400 rpm) when the gear is fully retracted, disarm the bomb doors at 140 K, climb power (36 inches, 2,300 rpm) at 148 K and up we go at 1,500 to 2,000 feet per minute (fpm). At maximum weight a climb speed of 160 K to 180 K to take advantage of extra cooling of 800 fpm on a warm day. Full throttle altitude is 9,000 feet (2,745 m) because the High supercharger is inoperative, but flights above this height are rare except in the mountainous areas.

Once level at our selected altitude we accelerate to cruise speed and come back to cruise power (30 inches,2,050 rpm; 31 inches, 2,100 rpm when loaded) and enjoy the contented purr of those big Pratt & Whitneys as they churn us along at a respectable 225K; almost four nautical miles every minute. Even on a single engine, with a propeller feathered, the same cruise power will give us 145 K, which incidentally, is the normal cruising speed of the Douglas DC-3 with both engines running!

The aircraft trims up nicely and has light and responsive flight controls. A 60 bank turn is as simple as rolling on the bank, giving a bit of rudder to co-ordinate the turn and pulling it around. However, control forces increase considerably between 250 K indicated airspeed (KIAS) and the maximum allowable speed (Vne) of 310 KIAS.

You'll be glad you ate your spinach as you wrestle with the controls at these speeds! Power-on and power-off stalls are preceded by mild buffeting, albeit at slightly higher speeds than might be expected, but there's a lot of warning and recovery is straightforward. Spins? Aerobatics? Nope, they're prohibited.

Back at the airport the Invader lends itself nicely to an overhead break, similar to the jet fighter circuit, at 180 K or to the more conventional traffic pattern. Regardless, the aim is to be downwind at 139 K, 20 degrees of flap, 2,400 rpm-setting the throttles at 25 inches should work just fine. Turning base: landing gear down, flaps 20 to 38 degrees as required, speed 130 K. Turning final: three greenlights for the gear, brakes checked and hydraulic pressure up, flaps 38 degrees, speed 120 K. Short final: full flaps, fence speed 110 K, threshold speed 100 K. Touchdown at 90 K. We hold the nose up as long as possible to take advantage of aerodynamic braking.

Once the nose wheel is down we'll momentarily check the brakes, easy does it, and avoid using them again until we're below 60 K. It's easier on the brakes and avoids excessive heat build-up, heat which can lead to brake-fading as the end of the runway looms in the windscreen-guaranteed to raise your adrenaline level! Once we're clear of the runway and the postlanding check list is performed, we taxi slowly to the ramp, park and shut down".

Taken from Captain W.M. (Turbo) Tarling's site
















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