Trivia Testers : Unfriendly Skies

Unfriendly Skies

The first aerial combat between two aircraft took place

  1. between an English and a German dirigible over France, in 1912
  2. between two Americans over Mexico in 1913
  3. near the beginning of WWI, in 1914, between two unidentified observation planes
  4. on April 1, 1915, when the Jean Navarre brought down his first enemy aircraft with a rifle (This was also the same date that Roland Garros scored his first victory.)

Answer: B. In late November, 1913, the first known aerial combat took place over Naco, Mexico, between two Americans: Phil Rader, flying for Gen. Victoriano Huerta, and Dean Ivan Lamb, with Venustiano Carranza (two opposing leaders during the Mexican Revolution). Although the exact details are unknown, about a dozen pistol shots were exchanged. Neither pilot was wounded, and neither aircraft sustained damage.

Weird Wings
Which of the following innovations never existed:

  1. wings that folded in flight
  2. wings that changed their angle of incidence in flight
  3. wings that changed their camber or shape in flight
  4. wings that telescoped in flight
  5. wings that inflated, …or
  6. none of the above

We’ve all seen some pretty wacky ideas when it comes to wings, whether that means their shape, configuration, or (especially during the earliest years of aviation’s first century) their number. Earlier Trivia Testers have discussed multiplanes, variable- geometry wings such as those of the Messerschmitt P-1101 jet prototype or the more modern “swing-wings”, forward-swept wings, and even ornithopters. If it was possible, it’s likely that someone, somewhere, has tried it. (Well, it’s likely, but it’s not absolutely certain–hence the question).

There have been wings with anhedral (negative dihedral), inverse taper (wider at their tips than the wing roots), and some designs have even involved so-called “Magnus flow” over wings that would simply consist of rotating cylinders (but that wasn’t one of the choices). In a way, many common aircraft involve using wings with variable camber (choice C); Fowler flaps and leading edge slats already do that. Research aircraft such as the F-111/MAW (mission adaptive wing) have gone a step further, using integrated leading and trailing edge segments of flexible fiberglass which were internally articulated and allowing completely variable camber along the full span of the wings. (Actually, NACA’s H.F. Parker proposed a true variable-camber wing in a 1920 paper.)

There have also been variable angle of incidence wings (choice B). Back in 1931, one George Cornelius tried a variable-incidence wing aircraft and followed it a few years later with his “Mallard,” which had both variable incidence and forward-swept wings. Variable incidence wings of course exist in powered lift aircraft (like some tilt-rotors), and also were involved in early designs such as the Boeing Vertol Model 76 (aka VZ-2A) in 1957, or the Canadair CL-84 in the mid-sixties. The Martin XB-51 also had variable-incidence wings (and in both of these last two, the tail plane tilted to match, as well). The F8U Crusader tried a variable incidence wing. The entire leading edge and ailerons could also be lowered to increase wing camber and reduce approach and landing speeds, and also rotated about its rear spar to raise the whole wing (which improved the pilot’s visibility). The outer wing tips could also fold for carrier storage.

And speaking of folding wings, the short-lived XB-70 Mach 3 bomber had wingtips that would lower in flight by 25 degrees above 300 knots, and down to 65 degrees when above Mach 1.4. One of the most extreme examples of a folding wing was in fact a biplane whose entire lower wing folded in flight, making it into a monoplane! (So much for choice A.) By about 1940, almost every country (except Italy and the Soviet Union) had given up on the production of biplane fighters, as designers couldn’t compensate for the slower speed caused by the drag of a second wing. However, the Soviets had a novel idea: in about 1940, the Nikitin-Sevchenko design bureau (V. Sevchenko & V.V. Nitkin) built a series of aircraft called the IS-1, IS-2, and IS-4 (for Istrebitel Skladnoj, or folding fighter) in which the whole lower wing was designed to retract into the upper wing, in flight, and after the landing gear had retracted into the lower wing! It had a cantilevered gull wing anchored in the top of the fuselage, forward of the cockpit. The lower wing had an inverted gull shape. For takeoffs and landings, the bottom wing was extended and locked, but once airborne the pilot could crank up the hinged lower wing, aided by hydraulics. The inner wing panels, into which the wheels were retracted, fit upright inside wells in the side of the fuselage. The outer panels bent at a right angle to the inner ones and also fit into wells, but in the underside of the upper wings. Thus, it was more than a clever compromise between a biplane and a monoplane fighter: it was both. In a way, it was an early form of variable geometry wing. In its biplane configuration, it had excellent takeoff and landing ability, as well as increased payload, while as a monoplane, it had both a higher speed as well as greater range.

As for inflatable wings (choice E), that’s nothing. Would you believe an entire inflatable airplane? In 1956, Goodyear designed and built several (a dozen, actually) prototype inflatable aircraft. It was called the XAO-3 “Inflataplane”. The single-seat version had a wingspan of 22 feet, cruised at about 60 mph, and it had a range of about 390 miles. The two-seat version was a bit bigger and slower. (Of course, powered parachutes and paragliders can be said to have “inflatable” wings, too…)

Then there’s the telescoping wing idea: This was another contender for an early type of “variable-geometry” aircraft; it was built in France and made its first flight in August of 1931. It was designed by Mikhail Makhonine, a Russian engineer. The MAK-10’s outer wing panels actually retracted into the inboard panels. A low wing monoplane, its wings were each made up of three sections. The first one was made of metal and was built into the slim fuselage. The second and third were made from wood, and could be moved on rollers to telescope inside the metal section. With wings fully extended (from 43 to 69 feet and with a surface area increase from 226 to 335 square feet), although its top speed did drop by about 30 mph (from about 155), its range increased from 6220 to 7480 miles. The concept of variable-span or retractable wing airplanes has also since been further explored by the military, individual entrepreneurs in other countries including the US (e.g., the Gevers “Genesis” aircraft), academia (Virginia Tech for example), and other organizations (such as the AIAA), whether for improved tactical versatility or simply “roadable” aircraft. The advantages of such versatility are, at least in theory, alluring. With its shorter span, along with reduced drag and higher speed would come greater wing strength, an improved ride in turbulence, lighter stick forces at high speed, natural protection from icing on the outboard wing sections until needed for landing, it could simulate higher performance jet aircraft for advanced pilot training… and it could fit in smaller hangars! With its wings stretched, in addition to greater endurance and range, it would also have an improved climb rate, better handling and control at low speeds, a higher ceiling, better glide ratio, lower takeoff and landing speeds as well as ground run…so what’s the catch? As usual, probably a combination of developmental inertia, sparse infrastructure, the economy, demographics, and engineering complexity that isn’t obvious to anyone but engineers. But scratch duck “D” in this line-up.

So the answer is: choice F. (Yes, it was intended as a double negative; none of the above never existed.)

Retractable WHAT?!
True or false: There have also been retractable hull aircraft.

Answer: True. There are retractable landing gear, someone tried retractable (telescoping) wings, some motor-gliders have retractable propellers, so why not try a retractable hull? Britain’s Blackburn Aircraft Company built an aircraft (a seaplane) with such a so-called retractable hull. Cumbersome “stepped” hulls, necessary to allow the hull to overcome surface tension during takeoff before it could climb up “on the step” (as well as keeping the prop above the spray), or clumsy flat-sided hulls were inefficient once airborne. Their top speeds didn’t get much over 200 mph. The twin-engine B-20 had a water-tight hull section attached to the fuselage by folding struts. Upon looking at this picture, one might conceivably be tempted to think this was nothing more than one big retractable pontoon and an overblown topological non-sequitur, but since it was in fact a section of the lower hull, it qualifies (sorta). Once airborne, the pilot retracted this extended hull segment snugly against the bottom the fuselage. Speeds in excess of 300 mph were expected, but sadly, the prototype crashed in 1940, and then the project was abandoned in favor of higher priority war efforts