A Wing And A Prayer
True or false: It is possible to maintain control of (as well as land) an airplane that is missing part of a wing.
Answer: True. In March 1945, a pilot was flying the military version of the DC-3, a C-47, when his left wing was severed in a mid-air collision. The wing, from just past its left engine out to its wingtip, was completely gone (or as the FAA might say, it had departed the aircraft). He managed to maintain control and land (sort of). In another case, a North American B-25 Mitchell bomber, from the 77th Bomb Squadron in the western Aleutians, was making bomb runs on the northern Japanese islands during the end of World War II (also 1945) when ground fire took out a large portion of the left outboard wing panel, including the aileron. They also managed to limp back to their base on Attu Island, in the Aleutians. Other similar incidents have occurred, some not quite as severe, such as when a commercial DC-3 pilot took his passengers sight seeing near Phoenix, AZ in 1957. He got too close to a mountain and took a few feet off of the left wing tip, but he made a normal landing. In another instance, a mid-air collision clipped 5 feet from one wing of a Capital Airlines DC-3, but its pilot also landed safely. There was also the Pan Am Boeing 707 that departed SFO in June of 1965: The number four engine disintegrated, taking 25 feet of the right wing with it. An emergency landing was safely made at Travis Air Force Base, with no casualties. According to Barry Schiff, all you need is “enough wing on the mishap side to prevent a roll.” In the case of the B707, it had manually operated flight controls (except for the rudder, which was hydraulically controlled). But the biggest difference between transport category aircraft like the 707 and light airplanes is that the cables to the ailerons (and in the case of the 707, the spoilers) were independent of one another, so losing the cables to the outboard aileron wouldn’t affect everything else.
So how does that translate down the food chain to the pilots flying those smaller general aviation airplanes? On almost any airplane, the pilot’s control inputs are transferred out to the ailerons either by a system of pushrods or via cables and pulleys. On a Cessna, the cables for each respective wing are not all on one “clothesline” type arrangement between two pulleys on either end, and there is some independence between the two. However, on almost any airplane, there are articulated mechanisms, such as bellcranks, usually located on the inboard end of each aileron, for transferring control inputs directly to these very crucial surfaces. If one were to become jammed by torn or bent metal however, that could conceivably lock up the controls for both ailerons. This would apply to the pushrod type systems, as well as those with cables.
I’ll just fly between the raindrops…
What popular airplane had control problems when flying in rain?
- the Wright Flyer
- the Vari-EZ
- the Spruce Goose
- the popular Reno racer “Rare Bear”
Answer: B. Actually, both the Vari-EZ and the Long-EZ, which have laminar flow canards, experience aerodynamic changes and exhibit some significantly adverse changes in control characteristics when flown in rain. This is because they are laminar-flow wings, and when it rains, the raindrops trigger boundary-layer turbulence. Likewise, deciding to paint decorative stripes on the leading edge of a canard can–and has–also caused difficulty in maintaining pitch. So might flying through a swarm of bugs. (yuck!) Laminar flow wings actually stall at a lower angle of attack, as the air does not stay “attached” to the wing as long as when the boundary layer air is churned up, which is one reason that some pilots install vortex generators to delay the onset of a stall!
Good help doesn’t come cheap
The cost of producing one Boeing 777 is approximately the same as that of building
- an entire shopping mall
- a mid-size high school
- a 40-room mansion in Beverly Hills
- a B-2 bomber
Answer: A. No, it’s considerably more than a school, or a mansion (though not quite as much as the B-2, which is over one billion dollars a copy). The going price for a B777 is about 135 million dollars. Something approaching half of that is for the computer systems and flight instrumentation alone. The number may seem staggering, but costs such as this are not that much more, in an order-of-magnitude sense at least, than for most large commercial transport category airplanes, and even such huge investments are more than amortized over their expected lifetimes. (For example, if you assumed a 300 seat configuration, that would come to $450,000 per seat. Assuming a per-seat cost of $200 per flight, that would require 2,250 flights, and assuming just two flights per day, the airplane could pay for itself in just three years…that is, if you ignored overhead costs like payroll, fuel, ground support, maintenance, landing fees, insurance, etc.