History of Spins
Parke
A test pilot, Wilfred Parke, was in a Roe Avro while making a spiraling descent. He inadvertently entered a spin when he failed to remove bank while applying backpressure. Parke made several power and control changes without effect. Parke finally applied and held opposite rudder. The aircraft recovered from the spin and entered a dive. An aviation first.
A few months later he was killed, after engine failure, while turning back to the runway. Apparently, knowing how to recover from a spin is of no avail if you are not aware of the conditions and initiating factors for spins.
Without altitude a recovery in time may not be possible.
Lindemann
SPINS WERE A ONE TIME THING IN 1914
An unheralded aviation pioneer is British scientist, F. A. Lindemann. "The Prof", as he was known, led a very checkered scientific and social career from early "idea man" and advisor to Churchill for thirty years. He was a social butterfly and a scientific gadfly to more capable scientists. However, his place in history could well lie in aviation. You never heard of him?
Born of German/American parents, he spoke heavily accented mumbled English. He knew all the "right" British nobility and used their influence to gain both position and prestige. In 1914 he attempted, but failed because of eyesight, to join the Royal Flying Corps. He then used influence to join the scientific staff of the Royal Aircraft Factory.
Lindemann initiated a study of the instrument readings and pilot procedures that seemed to cause the stall/spins occurring during turns. A letter to his father stated, "Nobody can make out quite what happened." Lindemann could find no apparent pattern as to when a stall or a resulting spin might occur. Once an aircraft was in a spin there was no way out of it. The spin turns would increase in speed until the ultimate crash. All flight instructors warned, "Get into a spin; get killed".
The "spin" was the most dreaded unintentional flight occurrence, which resulted in accidents. More to be feared than the more frequent landing accidents. At least, landing accidents could be explained. Lindemann now had an explanation, a theory, about spins.
While never publishing his study results, Lindemann gave many oral accounts of his findings. The spin frequently occurred when the aircraft stalled in other than an absolutely level condition. If one wing dropped any effort to raise it would cause the other wing to flip over the other direction uncontrollably. Even at high speeds, a tight turn might cause one wing to flip over and cause a spin. He insisted that further study to prove the theory required that scientists fly.
Without any flight skills, Lindemann had worked out in theory the probable forces, which caused and existed in a spin. He also figured out, in theory, the control movements required to counteract these forces. His study showed that any instinctive response would not work. The rudder must be held fully against the spin while the nose was kept pointed toward the ground. You could not pull back on the stick until the spin stopped and flying speed was gained. His theory also seemed to indicate that during the recovery the wings of the plane could be pulled off. The way Lindemann used to test his theories was somewhat akin to a medical researcher doing a self-inoculation for a deadly disease. He worked through and around the bureaucracy, used influence, memorized the eye chart for his "blind" eye and learned to fly "poorly". One flight of uncertain date in 1914 justifies Lindemann's place in history.
On this Fall day, he discussed his theories on spin recovery and the planned experiment with selected observers at Farnborough aerodrome. He told them he would deliberately do a stall spin. He certainly must have said his good-byes. He would be using a B.E.2 aircraft of most uncertain flight characteristics. He departed and climbed for many minutes. Far below, the observers saw him reach what must have been the B.E 2's service ceiling of 14,000 feet. They saw the spin well before they heard the cessation of engine noise.
Lindemann now began to test his theory. He pulled the power, slowed the plane and entered into a stall. He held the stall until the left wing dipped and the right wing flipped up for the spin entry. A deliberate entry into a maneuver from which no one had previously recovered and few had survived. A maximum test of accountability and courage.
The fragile airframe was held together by a maze of wires and struts that maximized a power off vertical speed of about 90 mph. Lindemann held the spin, intentionally or otherwise, until it was fully established and then he initiated his unique recovery. A planned application of control forces never before applied. He put in full opposite rudder. Nothing happened. He waited. Still nothing happened. He applied forward control pressure.
He had already fallen thousands of feet with no control effect discernible. Was his theory going to fail at this critical moment? But the rudder was starting to have an effect. The spin was slowing and finally stopped. From the vertical, but without the spin Lindemann now had to complete a recovery. Survival demanded that the pull out would not remove the wings from the fuselage. Slowly, carefully the nose rose and as it rose the aircraft slowed thus easing the stress on its components. The first intentional spin and recovery. All that and survival. Enough?
One such experiment and proof would have satisfied most people, but not Lindemann. He climbed back up to altitude and did the spin and recovery in the other direction. A theory twice applied and proven to be a life saver. From that day on, a pilot's education has not been deemed complete without spin training. (Except, of course, in the U.S. by the FAA)
The British had a military secret. It combined two of the very best qualities of military combat. Deception and kill'. Imagine their chagrin when the British plane would level out close to the ground and scoot to safety. Indeed, the spin was often used in
Most great aircraft flights recorded in aviation history are about distances, speeds and kills. Why not a special "save" category for Lindemann along with Immelman? But again, wouldn't your entering his name into your memory and applying his theory and practice to your own "Lindemann" spin recovery be sufficient.
The Airplanes
Normal category aircraft that are placarded against spins must be considered as being non-recoverable from spins. Certification today does not include ability to recover from a fully developed stabilized spin. The required one turn recovery is only the incipient stage of the spin. Aerobatic aircraft have not been tested beyond six turns.
There are legitimate concerns as to just how effective having an aircraft placarded against spins will be in preventing distraction caused spins. Aircraft design, pilot knowledge, enforced training standards, and pilot proficiency are historic causes and corrective factors.
The design of an aircraft rudder section that remains clear of the shielded air that occurs over the horizontal stabilizer and elevator makes for positive spin recoveries. If the empenage extends below the tail if gives a preferred nose down spin. The intent of the T-tail was to provide this desirable clearance but it sacrificed pre-stall buffet. Horizontal stabilizer fillets and a long dorsal fin improve recovery characteristics. One two-place trainer may not recover if loaded over over-maximum gross weight.
Some four-place aircraft rotate so rapidly that the rudder cannot stop it. Requires a parachute. Other aircraft the recovery is too quick when the ailerons are turned into the yaw direction. The resulting secondary stall precipitates a spin in the other direction. The full, abrupt forward elevator control can create an inverted flat spin. There is no place where a pilot can find the names of the aircraft involved.
The normal category of aircraft is certified for a one-turn spin followed by normal recovery. One turn is still in the incipient phase with weak rotational forces and unstabilized condition. Spinning an aircraft placarded against spins means the pilot is aware that any spin may be uncontrollable and unrecoverable. There are those who would blame the stall/spin accident prior to 1949 on aircraft design. There are those who would say the problem is lack of training, since in that 1949 period solo in less than ten hours was very common.
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