World's worst planes

The BBC has an article (with photos) by Stephen Dowling about planes that didn't make it:

The history of aviation is littered with aircraft that failed to live up to expectations. Here are some of the most serious aviation failures: from nine-winged monstrosities to a plane with flapping wings.
It's more than a hundred and ten years since mankind first took to the air in a powered aircraft. During that time, certain designs have become lauded for their far-sighted strengths: the Supermarine Spitfire; the Douglas DC-3 Dakota; or the Anglo-French Concorde supersonic airliner, to name a few.
But then there are planes like the Christmas Bullet. Designed by Dr. William Whitney Christmas, who was described by one aviation historian as the "greatest charlatan to ever see his name associated with an airplane", this ”revolutionary”prototype biplane fighter had no struts supporting the wings; instead, they were supposed to flap like a bird’s. Both prototypes were destroyed during their first flights, basically, because Christmas' "breakthrough" design was so incapable of flight that the wings would twist off the airframe at the first opportunity.
Just many of the world's most enduring designs share certain characteristics, the history of aviation is littered with disappointing designs. Failures like Christmas' uniquely unflyable aircraft often overlooked some fairly simple rules.
Britain’s now defunct aircraft maker Blackburn scored a double design-failure whammy in the 1940s. Their Roc was intended to be a fleet defense fighter, protecting bombers and strike planes from enemy fighters, and keeping a watchful eye over friendly ships. To that end, Blackburn decided to stick a four-machine-gun turret behind the pilot (the kind usually seen on multi-engined bombers) and take out any front-firing guns. The weight of the turret meant the Roc was far too slow; what’s more, the guns wouldn’t fire properly unless the aircraft was flying in a straight line (try that in a dogfight). The Royal Navy refused to allow the Roc to fly off its carriers, and the aircraft only managed to shoot down one aircraft, a German Junkers bomber, in the entire war.
Blackburn’s Botha, meanwhile, was a two-engined torpedo bomber and reconnaissance aircraft, which first flew in 1938. The first problem? The view from the crew compartment was so appalling that the aircraft was deemed useless as a recon plane. Next, it turned out it was dangerously underpowered; the extra weight from suddenly having to carry an extra crew member meant the plane would have struggled to carry its intended torpedo armament. When they were phased out of frontline service in 1941 they passed onto training squadrons, but the Botha was so tricky to fly that there were many accidents. The Botha ended up being a failure, never fulfilling the roles it was designed for.
World War One provided the impetus for a great deal of successful aviation experimentation: from monoplane to biplanes to triplanes, and aircraft with the engine and propeller mounted behind the aircraft. The Royal Aircraft factory BE9 tried to go one step further: separating the front gunner and the pilot with the plane’s engine and propeller. This was meant to give the gunner an unimpeded field of fire, but also meant he could be crushed by the engine during a crash, or sliced by the whirling propeller blades. Hugh Dowding, who later commanded RAF defenses in the Battle of Britain, took one look at it and declared it “an extremely dangerous machine from the passenger's point of view”.
In the 1920s, Italian plane–maker Caproni designed the Ca 60 Noviplano to fly a hundred passengers across the Atlantic. It must rank as one of the ugliest things to ever take to the air: it had no less than nine wings, in three sets of three, and eight engines. The cumbersome beast flew only once, from Italy’s Lake Maggiori, and reached the dizzying height of sixty feet before crashing back down into the water (the pilot escaped unhurt, though the wrecked aircraft was destroyed in a fire after being dragged ashore). Nine-wing planes have been conspicuously absent from aviation record books ever since.
The Fairey Albacore was a carrier-based torpedo bomber designed to replace the venerable Fairey Swordfish, a canvas-covered biplane with open cockpits that served on the front line at the beginning of World War Two. The two-wing Albacore had a modern, more battle-friendly enclosed cockpit and was more aerodynamically streamlined, and it began replacing Swordfish units in 1940. But crews didn’t take to it; the Albacore wasn’t pleasant to fly, and pilots insisted on flying the Swordfish instead. Albacores were retired in 1943; the last Swordfish didn’t come off the production line until a year later.
The Soviet MiG-23 was the backbone of Warsaw Pact fighter fleets in the 1970s and 1980s, and equipped many other air forces around the world. It was designed to replace the delta-winged MiG-21, which had been serving since the late 1950s. The MiG-23 was much faster and had a modern, swing-wing design, but the pilot sat in a narrow, cramped cockpit with poor rear view. Furthermore, the lighter, more nimble MiG-21 was a much better dogfighter. When the Cold War ended, many air forces ditched their MiG-23s, whereas hundreds of MiG-21s are still in service two decades later, and production of Chinese-built versions only recently stopped.
Two aircraft from the final days of the Third Reich show desperate times shouldn't always call for desperate measures. The Messerschmitt Me 163 Komet was a rocket-powered interceptor developed to shoot down the heavy bombers raiding Germany. The Komet could fly a hundred miles per hour faster than any Allied fighter plane, but it had only three minutes worth of fuel, then the aircraft had to glide back to base under its own power. One problem was the fuel; an oxidising agent called T-Stoff helped power the plane, but it was so volatile it would combust on contact with clothing or leather. Even fuelling the aircraft was a hazard.
The Heinkel He-162 was another last-ditch design for the Nazi regime. The advanced He-162 went from first drawings to production in ninety days; the Germans drew up plans to build three thousand of them a month. The wooden He-162 was designed to be flown by teenage pilots with only rudimentary training, but the He-162, though an excellent design, needed careful handling. Things weren’t helped by the location of the engine, right above the cockpit, meaning escaping pilots ran the risk of being sucked into the engine. Also a major design flaw was that the glue used to stick the plane together actually corroded the airframe.
In the years after World War Two, Britain’s aircraft industry was in rude health, creating many advanced designs. The first jet airliner in the world was British, the de Havilland Comet, which entered service in 1952, long before Boeing’s 707. But there were flaws in the Comet design, chiefly with the square cabin windows, which added more stress on the airframe than rounded windows. Three Comets broke-up in mid-air soon after entering service and the accidents made global headlines, and Britain’s pioneering jet airliner industry never fully recovered.
Not all flawed designs end their days on the scrapheap. The Douglas DC-10 medium and long-haul airliner ended its flying days with a good safety record, but only after a series of serious issues were discovered back in the 1970s. Chief of these was the design of the plane’s cargo door. Instead of opening inwards, they opened out; Douglas’ designers figuring this left more room to load cargo. The doors needed to be closed with heavy bolts and then locked with pins on the outside of the aircraft. But the pins would be “locked” without the bolts having been properly fastened, meaning there was no way to be sure the cargo doors were locked. At least two aircraft were destroyed in such crashes, including a Turkish Airways DC-10 which crashed in France, killing nearly 350 people. The DC-10 was briefly grounded by US aviation chiefs, and while the flaw was fixed, the DC-10 struggled to rid itself of this bad reputation.

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