| A model 75-85 Knight Twister Junior with 15 foot wing. |
There is something about small biplanes that excites the flying man almost as much as a trim feminine ankle. If he happens to be an amateur builder, then for certain, sooner or later, he will be smitten by the urge to build one. The one ship that is likely to fire him with enthusiasm more than any other is the Knight Twister -- for before any builder constructs any other type of biplane, he must first talk himself out of building a Knight Twister.
The first KT was conceived in 1928 in a classroom of the Aviation Service and Transport Company in Chicago, Illinois. Vernon W. Payne was in the middle of a rather dry dissertation, which was succeeding only in putting his students to sleep. In desperation he chose another subject, one that he knew would end the yawning and nodding of heads. He began talking about minimum size sportplanes and he made a few sketches on the blackboard. While not in the school curriculum, the new subject had the desired effect. The students woke up, one by one, and before long were taking part, with enthusiasm, in the ensuing discussion. As Payne talked, he sketched on the blackboard and by the time the class ended he had completed the rough outline of a tiny biplane -- a biplane that was destined to become famous.
Payne and his students quickly recognized that the blackboard sketch had merit, and it was not long before it was designed on paper as a classroom project. A panel of the wing which was built and statically tested to destruction, proved the great strength of the structure. The fuselage followed and this, too, was loaded with sandbags to design limits. The students would have continued and completed the little ship if it had not been for the stock market crash of 1929. Aviation Service and Transport's school folded soon after, and the parts that had been completed disappeared.
Two years were to pass before any further work was done on Payne's little biplane. It was in the rear of a public garage in 1931 that the first Knight Twister began taking shape. Before the plane was finished, Popular Aviation, the leading air magazine of its day, became interested and, as a result, a series of design and construction articles was published. The response to these articles was immediate and highly significant. This was the dream-ship that many had hoped for.
The fuselage was eight feet long from the firewall to tailpost. It was of welded steel tubing, and the longerons were spliced in such a way that the longest piece of tubing was no more than five-and-one-half feet in length. Most amateur constructors could scrounge up enough scrap tubing to build a fuselage of this size for practically nothing. For once, space in which to build the airplane was not a problem. You could very nearly build the fuselage in a clothes closet.
| The first Knight Twister, 1932. |
| A front view of the original KT. The KTS-1 is powered by a 45 h.p. Salmson AD9 seven-cylinder radial engine; its span is 15 feet (13 feet for the lower wing) and length, ten feet, nine inches. The KTD-2 is powered by a 70 h.p. Douglas Bear-Cat inverted four-inline engine. Its dimensions are shown on the following pages (an improved KTD-2 of 1935-36). |
The wing was not quite so simple. Most amateurs of the 1930s avoided such sophisticated design features as cantilever construction, tapered or ply-covered wing. The KT wings employed all these techniques, yet they were comparatively easy to build. The spars were solid and straight in plan view, the wing tips were faired with balsa blocks and the plywood covering was a simple flat-wrap operation. No external bracing was required since the test wing had proved its strength. However, pilots of that period were always suspicious of cantilever construction, so the KT was fitted with interplane struts and a flying wire for good measure.
| An improved KTD-2 of 1935-36. [Top view obscured in our copy of the article - ed] |
Construction was completed in the fall of 1932, and initial test flights were conducted by "Curley" Cushman. It was subsequently flown by many others and all proclaimed it to be an exceptionally stable airplane for one so small. As a rule, ultra-small aircraft tend to be nervous and require constant attention, but this was apparently not the case with the first KT.
Stout fuselages with blunt radial engines, such as the KT had, often reveal directional and longitudinal control problems. They have an annoying tendency to disrupt the airflow and reduce the effectiveness of the empennage. If the elevator and rudder work well [last few words obscured due to poor quality copy - ed] enough to give positive control at low speeds, invariably these surfaces are too sensitive at high speeds. The KT was no exception.
The rudder and elevator were sensitive and efficient at normal flying speeds, but seemed a little inadequate at landing speed. The original horizontal tail, which had a six-foot span, was replaced with one a foot wider. This improved the control at the low end of the scale, but resulted in excessive sensitivity at normal cruising speeds. After a few test flights, the original surfaces were reinstalled and these have remained unchanged in all subsequent models.
Both the fin and the rudder were subject to frequent change. Originally the rudder was balanced aerodynamically; in other words, the rudder tip extended [words obscured due to poor quality copy - ed] portion and adding the area to the fin. Next, a six-inch extension to both fin and rudder was tried, and then twelve-inch extensions. These experiments proved unsatisfactory, so the vertical surfaces were finally reduced to almost the original area, but without the overhanging balance on the rudder.
Up to this point the little biplane was nameless. Payne, who held a teaching job during the day, wrote technical articles and built airplanes at night. Most of his students were in the same boat, working at odd jobs during the evenings to supplement their meager finances. During bull sessions they often had occasion to complain about the night work. In an effort to pacify them, Payne once pointed out that even the knights of old had to take on spare-time work slaying dragons and assorted ogres to make ends meet -- and it was often highly rewarding to rescue fair damsels in distress at night. This kind of spare-time employment was referred to as "knight's work." Before long everyone was calling the airplane the "Knight Work."
During a session following a test hop, the youngest member of the group expressed great concern over a tendency of the airplane to wobble and cavort curiously as it passed over the field. It seemed that the pilot, identified only as "Frenchy," was afflicted with a head cold and on each sneeze the airplane would porpoise ina most alarming fashion. The lad remarked "If they all fly it like Frenchy, it's going to get all twisted." Immediately someone tagged the plane "Knight's Twister." It was the late Mr. Rathbun of Popular Aviation who finalized the name to "Knight Twister."
[Note: For most of the remaining text, the first word of each line on the original copy was cut off. There may be minor errors in the text due to this. - ed.]
It never seems to fail -- the day the press is invited to view a new airplane, something goes wrong. The Knight Twister's debut was no exception.
The day was cool and bright, and Curley Cushman's passes across the field was spectacular. In fact they were almost as spectacular as the dead-stick landing he tried when the gasoline supply gave out. In the hustle and bustle to clean up the ship and ready it for the press photographers, no one remembered to fill the gas tank.
Flying low and circling the field in full view of the spectators, Cushman clearly had only one choice of direction in which to go when the engine quit -- down. Down happened to be a golf course which, on a normal day, would have been just fine. On this particular occasion the golf course was no better than a peat bog. It had been raining steadily for days and the surface had turned to mud a foot deep. The temperature during the previous night had been below freezing, so the ground had a thin frozen crust on the surface. It was so thin it would not support the weight of a man, much less that of an airplane.
As soon as the wheels touched they broke through the crust, buried themselves in the soft soil beneath and stopped dead. The rest of the airplane was not ready to stop, however. Quickly parting company with the landing gear, it cartwheeled down the fairway, apparently bent on smashing itself and its contents to very small pieces. Miraculously, when it did stop, both the Knight Twister and Cushman were more or less intact. The ship should have been a total wreck, but only the tail and fuselage, where the gear was shed, were damaged. Outside of a few holes, the wings were in perfect shape, a further testimony to the strength of the structure.
By 1935, the second version of the Knight Twister was ready to fly. Built for a South American playboy, it utilized the wings from the first airplane and also its registration numbers. This time power was supplied by a neat air-cooled 70 h.p. conversion of the Model A Ford automobile engine called the Douglas Bear-Cat. Whereas the forward half of the fuselage of the original KT was circular in cross-section, the formers of the Douglas-powered version were elliptical. The overall length was also increased, thus greatly improving the efficiency of the tail group. The controls were still sensitive at high speeds and remained effective down to the stall.
Redesignated the KTD-2, the aircraft was tested at the Curtiss-Reynolds Airport in Glenview, Illinois. Upon completion of the test flights, it was stored in a hangar to await its new owner. Months passed and finally the Latin sportsman put in an appearance. The KTD-2 was a beautiful little airplane and would have delighted the most querulous of pilots, but for some unexplained reason the gentleman refused to take delivery and departed for the place whence he came.
[text obscured on original copy - ed] airport manager **** auctioned the plane for hangar rent and subsequently became the new owner by sheriff's sale.
[end all obscured text - ed]
The Knight Twister passed through many hands and finally turned up in Columbus, Ohio, after the war. Payne bought it and hauled it to St. Louis by trailer, where it was completely rebuilt. A straight two-and-one-half-foot center section was added to both the upper and lower wings. This increased the gross wing area to seventy-three square feet. Leading-edge slots were built into the lower panels, which gave better aileron control at high angles of attack. A 75 h.p. Continental was installed and the overall length of the fuselage was increased to fourteen feet. In this form the airplane became known as the Model 75-85 Knight Twister Junior.
After completing the initial test flights, a small change in the carburetor heat system required one more test hop. The engine turned up on the ground satisfactorily, but started missing as soon as it was airborne, finally quitting altogether. The pilot panicked and, as so many have done, tried to turn back to the runway. There was neither enough altitude nor enough speed and the aircraft stalled in the turn, crashed and burned. The pilot, Richard Payne, the designer's son, was killed on impact.
The ended tragically the career of the original Knight Twister. While nearly a third of a century has passed since it first took to the air, the effect has been lasting. The Knight Twister is still a great favorite and will likely remain so for many years to come.
Webmaster Note: We do not know the original source or date of this article. Can anyone out there tell us what magazine used this symbol at the end of articles?