The Burnelli Controversy
Was this designer a genius or his own worst enemy?
- By David Noland
- Air & Space magazine, November 1989
(Page 4 of 5)
Since there are no Burnelli airplanes in flying condition, it’s difficult to evaluate Goodlin’s claims of superior performance. According to contemporary editions of Jane’s All the World’s Aircraft, performance of the early Burnelli CB-16 and UB-14 was comparable to similar aircraft of the day. The most modern Burnelli, the CBY-3, though close in power and payload to the Douglas Super DC-3, was a good 40 mph slower.
On the other hand, Goodlin points out with glee that Boeing’s own spec sheet shows that the 754 Husky would have had greater payload capacity than the 767. But the Husky had 31 percent more wing area and a higher aspect ratio—the ratio of span to average chord, a measure of the “skinniness” of the wing—than the 767, two factors that, entirely aside from its Burnelli-style fuselage, would give it a big weight-lifting advantage. Moreover, the Husky would have cruised at just Mach 0.74, compared with the 767’s Mach 0.80.
According to standard aerodynamic theory, the “extra lift” provided by a Burnelli fuselage is, under most conditions, beside the point. A Boeing 767 cruising at 41,000 feet doesn’t need extra lift from the fuselage. Its wing easily provides all the lift necessary to balance its weight. (In engineering terms, the aircraft cruises at well below the wing’s maximum lift coefficient.) The designer’s task is to get that lift with the least drag. It happens that a high-aspect-ratio wing (long and skinny) has inherently less induced drag than a low-aspect-ratio lifting surface (short and fat, like a Burnelli fuselage). In cruising flight, the less the fuselage lifts, the lower the inducted drag.
Conventional wisdom also dictates that a Burnelli jetliner would suffer drag penalties because of its larger frontal area, larger wetted area (the area over which air flows), and the discontinuity between the lifting fuselage and the wings. NASA aerodynamicist Jerry Hefner comments: “I would think the induced drag would be horrendous. And your skin friction drag is going to go up because of the larger wetted area.” An engineer from a major aerospace firm who asked to remain anonymous (to avoid angry letters from Goodlin) estimates the drag penalty of a Burnelli-style jet transport at about 20 percent more than that of an airplane like a 767. That may be a reasonable compromise for a bulky cargo carrier like the Husky, but not for a passenger jet.
Slick Goodlin, of course, has never let conventional wisdom get in his way. “Boeing and Douglas and all the rest of them are simply wrong,” he declares flatly. “The aerodynamics textbooks have been misinterpreted for 50 years.”
Goodlin and established aeronautical theory do agree on one thing, however: the extra lift of a broad, flat, airfoil-shaped fuselage can theoretically reduce landing speed. Goodlin correctly cites the takeoff and landing speeds of current jetliners—typically 140 to 180 mph—as potentially dangerous. All of Burnelli’s airplanes, by contrast, had low landing speeds.
But an airplane’s landing speed is essentially a market decision, one of the tradeoffs in aircraft design. If Boeing had wanted the 747 to take off at 100 mph in 3,000 feet, it could have simply enlarged the wing and limited the weight. But since the major cities of the world all have 10,000-foot runways and since there is no great public clamor for slower, safer landing speeds, Boeing saw no reason to pay the speed, payload, and cost penalties of a short-takeoff-and-landing 747, Burnelli or otherwise.
Goodlin may not win many converts to his aerodynamic theories, but he’s on much firmer ground when he criticizes the modern jetliner’s crashworthiness. Goodlin says the Burnelli’s rigid box-like fuselage would protect passengers in a crash, pointing proudly to the 1935 crash of the UB-14. The airplane hit the ground, wingtip down, at 130 mph and cartwheeled. Engines, wings, and tail were ripped off, but the boxy fuselage remained intact and the crew walked away. One vocal Burnelli proponent, Edmund J. Cantilli, professor of transportation planning and engineering at the Polytechnic Institute of New York, has decried the poor crashworthiness of the modern jetliner and proposed a Burnelli-style craft it its stead.