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Art is now a volunteer Ambassodor at Boeing’s Future of Flight Gallery at Everett’s Paine Field and is submitting these articles for the volunteer newsletter. They are meant to explain flight in the simplest way. Visit www.futureofflight.org for more information.
The first “What is Flight” article introduced the concept of a liquid, such as air, when moving faster over the curved top of a wing generate less pressure or a vacuum, theBernoulli Principal. In this article we discuss the parts of a very simple fixed wing aircraft. The physics of a simple aircraft apply to the most advanced 747 but, in a smaller scale.
So far, we have a fuselage with wings that pull or lift the aircraft up, a propeller to pull the aircraft forward and, stabilizers at the back or tail of the aircraft to keep our aircraft flying straight like feathers do for an arrow.
Now, how does the aircraft turn, climb and descend? Each wing has an aileron that is controlled by the pilot. For a left turn the pilot moves the yoke or stick toward the left and the left aileron moves up into the airflow, disrupting the flow and reducing the lift while the right aileron moves down, increasing the curvature of the wing top and increasing the lift. Right wing moves up and left wing moves down, and the aircraft turns left. Simple enough except, another law of physics from Isaac Newton complicates the maneuver. “For every action there is an equal and opposite reaction”, so as the right wing generates more lift it also generates more drag on that wing resulting in a yaw or sideways force. The nose of the aircraft moves up and to the right. The pilot then uses a panel attached to the vertical stabilizer to move the nose left to coordinate the turn. His rudder pedals at his feet move the rudder disrupting the flow of air, in this case toward the left counteracting the right yaw from the aileron movements. What happened to “Flight-Simply Speaking? “
The opposition force of drag causes the aircraft to slow and descent unless the pilot uses another control by pulling back on his yoke or stick which activates another panel attached to the horizontal stabilizer called the elevator. It raises up into the airflow, forcing a downward force on the tail and an upward movement for the nose. Finally, a coordinated turn to the left has been accomplished but with the increased drag the aircraft will slow and eventually ‘stall’ or quit flying unless the pilot increases an opposite force to the drag called thrust.
An aircraft deals with three axes; vertical or yaw, longitudinal or roll, and lateral or pitch. Our wing has ailerons to generate a turn and the vertical and horizontal stabilizers have a rudder and an elevator to coordinate the turn.
Our next article will discuss the several forms of thrust, without which we could never get airborne and wing flaps that increase the lift of a wing to allow shorter take offs and slower landings. The pilot is much like a conductor of an orchestra. His players are thrust, ailerons, elevator, rudder and a few other players that we will discuss in future articles.
FoF Volunteer Ambassador
We will start with a definition which is often debatable, but I will use the following for a starting point:
Flight is the process by which an object moves through an atmosphere (or beyond it, as in the case of spaceflight) without contact with earth’s surface. It needs enough upward force to counteract gravity.
A hot air balloon traps the raising hot air and lifts the basket up exceeding the pull of gravity. For horizontal flight, the object uses propulsion from a propeller or jet engine generating enough lift from the airfoil to counteract gravity.
Today we will discuss the force generated by an airfoil. This is explained by the Bernoulli Principal: the pressure in a stream of fluid is reduced as the speed of the flow is increased
Air is considered to be a fluid. An airfoil or wing typically has a flat bottom and curved top. As the air passes over the top of the airfoil, the speed increases and the pressure decreases thus generating a vacuum that pulls the wing upward. This is the same effect from a propeller that has the shape of an airfoil. The propeller has a lower pressure on the front thus pulling the aircraft forward or upward as in a helicopter.
A hot air balloon simply uses trapped hot air to ascend and has little or no control of direction. A rocket uses an engine that produces upward thrust to ascend with some limited directional control. A baseball pitcher uses his strength to propel the ball and can change its direction by inducing a spin allowing the Bernoulli effect to curve the ball. A knuckle ball has little or no spin thus causing an uncontrolled flight path. These forces can be easily demonstrated by spinning a beach ball in various directions.
The wing generates upward force on the fuselage but provides no directional control. The directional stability is provided by the appropriately named stabilizers. A horizontal and vertical stabilizer are typically at the back of the fuselage.
Entering our gallery, at the bottom of the ramp, is an exhibit showing the Bernoulli Principal. The ball spins and stays levitated because of the pressure differentials. Just across from the exhibit is a huge vertical stabilizer. This is equally curved on both sides stabilizing the aircraft direction but not generating any forces to either side. This is an actual vertical stabilizer taken from 747 and an excellent example of how large the 747 is.
There are many aerodynamic forces affecting flight especially as noted in Isaac Newton’s Laws of Motion. Newton’s Third Law; For every action there is an equal and opposite reaction, generates a problem. This article introduced the useful element of lift. Future articles will explain how to deal with ‘the opposite and equal reaction’ often called drag and how, by modifying the shape of airfoils and stabilizes in flight, the aircrafts can climb, turn and descent.
FoF Volunteer Ambassador
As juniors, we had AFROTC classes on Tuesdays and Thursdays on the second floor of OregonStateUniversity’s Gill Coliseum. Before class began the seniors inspected us in an open ranks inspection. These were nose-to-nose, one-on-one events where the seniors shouted their questions and we roared our answers because, “I CAN’T HEAR YOU!” The events soon turned into mind games where the seniors tried to baffle us and we were intent on using mental judo to best them while complying. Had you been a bystander, you would have heard a lot of humor on both sides, but no one would laugh. My “chosen” inspector was Hank.
The battle of wits continued through the fall term and winter term, but by the spring term, we were tiring of it and the exchanges were becoming repetitious. We needed a change mechanism.
As a counter measure, I called some of my classmates the night before the next class and asked them to meet me at the southeast corner of Gill Coliseum a half hour before class. At the meeting, I passed out cloves of garlic and asked them to spread out to each of the entrances. They were to intercept the juniors and give them a bit of garlic to chew on before the inspection.
As Hank inspected me and we exchanged the usual at the top of our lungs, he had a quizzical look on his face. It was all I could do not to laugh. The other seniors weren’t amused. It was a short inspection.
We left the hallway for the classroom and waited for Major Paige to begin the class. As one might suspect, the room reeked. Normally prompt, Major Paige was late.
When he arrived, he waved the air in front of his nose, acknowledging the smell. But he had a small smile. He told us the seniors had gone to the cadre after the inspection and demanded the entire junior class be kicked out of AFROTC for the stunt.
Major Paige told us the cadre’s response was, “Well, at least they were organized.” When he asked us who had organized the event, I got fingered.
It was the end of the open ranks inspections.
Later, I asked Hank why he had been looking quizzical during the inspection. All though he had known something was going on, he couldn’t figure out what it was. Turns out that Hank had no sense of smell. What a waste.
This is an excerpt from “Hijacked, A Critical Change of Plans” A true story!
I entered primary jet training at Laughlin AFB, Del Rio Texas in September of 1967. I made it through the T-41 ‘Wash Out’ program but was still not sure I was meant to be a pilot. I was then and still am afraid of heights.
On October 21, 1967 a graduation ceremony of 60 lieutenants was conducted and all the current students were in dress blues to be inspected by Jimmy Stewart. He was in the area filming the movie “Bandolero” along with Raquel Welch, Dean Martin and George Kennedy. James Stewart was a USAF Reserve brigadier general and it was an honor to have him there plus the Thunderbirds were there with their F-100Ds.
The formalities were over and the T Birds were about to complete their famous ‘bomb burst’ when the solo pilot, Captain Merrill A. McPeak positioned his F-100 to climb up through the other four jets that had just orchestrated the bomb burst. At .99 mach he pulled the normal 6.5 G’s and his plane disentigrated. The wings had separated from the fuselage and as fire and smoke entered the cockpit he ejected. His winglesss flaming fuselage traveled over the ramp with parked and fully fueled T-37s and T-38s crashing harmlessly in the desert. Captain McPeak’s ejection was at such a speed that his helmet and oxygen mask was ripped from his head and a panel of his parachute was shreaded. He landed safely on base property with his ground crew and base ambulence waiting for him. He was taken to the hospital and soon released with just bruises and a few minor cuts.
That evening , the Officers Club was packed and I had the honor of speaking with one of the T-bird pilots. I asked him what Captain McPeak saw and did. He smiled and said its all part of aviation and our training. He reacted quickly when he saw the smoke and flames and all the systems worked. That short visit convinced me that I was meant to fly and anxious to be a part of such a professional group.
My job was to demonstrate some incorrect recovery techniques that the new instructor might encounter from his students. The normal recovery from a T-37 spin was;
-Rudder and aileron neutral
-Stick abruptly full aft (elevator) and hold (if inverted this will result in a recovery if not help too long)
-Determine the direction of spin (use outside references or the turn and slip indicator)
-Abruptly apply full rudder opposite the direction of spin and hold (note the ground reference)
-After one complete turn using the ground reference abruptly apply full forward or down elevator
-As the aircraft approaches a vertical attitude slowly apply up elevator and power as the aircraft recovers.
Some of the demonstration spins recoveries were:
-Wrong rudder-resulted in an abrupt bounce or opposite motion when the stick is applied forward
-Relax all controls (this was the normal recovery of a small propeller driver aircraft but did nothing for a jet)
-Stick only, no rudder applied. Worked sometimes but not guaranteed
-Accelerated spin-slow movement forward with the elevator resulting in a very fast continuous rotation blurring all ground references as the aircraft accelerated towards earth.
We climbed to 20,000 feet before starting the demonstrations and usually a ride that most new instructors were glad to have over.
A true life story form our friend Glenn H.
In April 1968 I pulled my Stinson 108, with a 150 horsepower Franklin engine, out of the hangar and did a preflight inspection. Prior to my solo flight I did a ground run-up checking the magneto’s for appropriate mag drop and temporarily applied carburetor heat to assure I had no carb ice. My fuel tanks were full of 37 cent a gallon 80 octane aviation fuel, I had no predetermined destination in mind, the day was clear and the air was smooth. Life was great! To escape boredom I climbed to 4,000 feet applied carburetor heat, reduced power and practiced some stalls. After the last stall I applied power and pushed the carburetor heat button in. To my surprise the engine ran very rough and produced only 1,700 RMP, which resulted in insufficient power to hold altitude. I again applied carburetor heat to no avail. I switched fuel tanks and experienced no improvement. I now realized I had a problem that I hadn’t previously encountered and didn’t have a solution. I surmised that I had a valve or cylinder problem. At this point I assessed my location and ascertained I was too far from any airport and my option was to land in a boggy field. Although a little panicky, I didn’t have any fear for my life, but knew an off-airport landing would probably total my plane and all the resulting problems of aircraft retrieval.
An in-flight magneto problem had never been a topic of conversation among my friends or in written format. To me, magneto’s were something that either worked or didn’t work. For some Devine reason I turned the magneto switch one click to the left and the engine immediately smoothed out. With a sigh of relieve I headed back to my home airport.
My A&P technician removed the offending Bendix magneto and replaced the coil. He ascertained that the offending magneto set up a crossfire which prevented the “good” mag from allowing the engine to perform properly. Magneto’s seldom fail, but when they do, they can do more than just go off line.
Reminiscing about USAF T-37 basic training brings back many memories but one has stuck with me my whole life.
I was doing well and knew I would make it as a young confident Air Force pilot. We broke for the Holidays and, my wife and I, returned to Seattle and my father-in-law mentioned that his neighbor, Mr Craig, had flown in the Royal Canadian Air Corp in WW I and he would like to meet me. I was thrilled and we hurried over to meet him.
He was well up in his years then but as I introduced myself I could see the excitement in his eyes to again talk aviation. He had found his leather flying cap and let me handle it as he talked about how they had to dress for the cold open air cockpits. I asked about their instrumentations and he smiled and said maybe a compass.
“But how did you know your speeds” I asked and he replied
” The sound of the wires cutting through the air was what we used”
I was amazed at the very basics of flight back then but when I began telling him about the spins and other maneuvers we practiced he understood and said they used stalls and spins as escape maneuvers. I told him how we performed barrel rolls and loops but when I mentioned Immelmann’s, a half loop with an aileron roll at the top, his eyes lite up and he proudly announced
” Oh yes. I knew Max Immelmann, he was a great pilot.”
A moment i will never forget.
The alarm sounded early to start my second day of a four day rotation. I was in Atlanta Georgia and scheduled to fly to Hartford Connecticut, back to Atlanta then to LaGuardia Airport in New York to spend my second night but those plans would soon change.
The date was September 11, 2001, the infamous nine eleven, that changed everyone’s life. My Co-pilot and I reported to Hartsfield Airport on a gorgeous day to fly, one of those days that makes flying the best job in the world.
The flight was uneventful up to just south of Washington DC when we heard Air Traffic Control mention that an aircraft had hit a tower and crashed. I first thought it might be a small aircraft having clipped a tower flying into a close by airport so I contacted our flight dispatcher who had heard similar chatter but knew nothing more. The visibility was unlimited as we approached New York City but that beautiful view changed quickly. A large plum of black smoke had just emerged from one of the Twin Towers and, I knew then, what the chatter was all about.
I thought there must have been a major mechanical or even a medical reason for such a large aircraft to collide into such a large visible tower. Air Traffic then gave us a change of heading and a new identification code as they began their emergency procedures for a terrorist attack.
We were given an order to descend directly to the Hartford Airport and after landing we taxied to our assigned gate The agent opened the entry door telling everyone to deplane quickly including the crew since the aircraft would be locked and the jet way removed.
“America has been attacked”
I told my crew to call their loved ones to say they are ok but to keep the conversations short since there would be a lot of calling.
We were told that a United and American Airlines aircraft had crashed but nothing more so, as I talked to my wife, I asked where Chris, our son, was. He was a new pilot for American and she too had almost no new information.
The crew was taken to our layover hotel and assigned to our rooms by a very worried and confused hotel staff. There had been four hijackings today, all of which had ended tragically. As I sat in my room and tried to gather my thoughts I couldn’t help but think of January 26, 1980 when I too was being hijacked.