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Aeronautical Engineering Blunder #1 THE REST OF THE STORY OF HOW AN AIRPLANE FLIES Aeronautical Engineering made 4 fatal errors early on that have produced the Blunders of the 20th century. The first of these was to accept the so-called Bernoulli Principle as the basis for evaluating air flow. These two simple illustrations should have alerted them to the problem of applying Bernoulli's principle to solving Aero Engineering's problem of how an airplane flies presents.
The second was in agreeing that Aero Engineering was a sub science of Fluid Dynamics and thus came under their jurisdiction as far a principles go. Quoting from the Fluid Dynamics reference material; “Fluid Dynamics is the study of the motion of matter in the gas, fluid, liquid or plasma state. When restricted to the flow of incompressible fluids, the term Hydrodynamics is used. When dealing with electrical conducting fluids with the magnetic fields present, the term megnetofluid dynamics is used. When dealing with practical problems of air flow past airplane wings, through ventilating equipment, etc. the term Aerodynamics is used”.
“A great simplification of the fluid calculations can be effected by assuming that the fluid is perfect, homogeneous, totally incompressible, inviscid, and that therefore its properties are not affected by changes in temperature, or pressure. While such an ideal fluid does not exist, its properties are often approached closely enough by real fluids so that calculations based upon it are often useful in practice”.
Fortunately, a perfect fluid really does exist! It is the fine sand in an hour glass!. The fluid is perfect (whatever that implies) homogeneous, totally incompressible, inviscid (at least the viscosity i sperfectly stable and not affected by temperature or pressure)! It would be difficult for me to comprehend that sand and air can come under the same classification for any purpose! "Thus elementary hydraulics always includes Bernoulli's law, and it is being repeated here as being of great importance to the subject of fluid flow" (Statement from Fluid Dynamics materials) First; Bernoulli's Principle is not a law for it has never been proven to be so, and, in the "Optimization of Lift" we have proved Aeronautical Engineering's analysis of how an airplane flies based on the Bernoulli Principle as totally indefensible. Fluid Dynamics is the study of directed or conducted fluids; water through pipes, electrical through insulated conduits, air through conducting tubes etc. We will do a brief analysis of each of these fluid flows.
Water, Hydrodynamics. ( Bernoulli titled his report of his water experiment Hydrodynamica)
Aerodynamics
Magneto-fluid dynamics
It is foggy thinking such as this that allows water and air to be considered fluids under the same laws.
The third was considering objects such as airfoils being tested in wind tunnels as the same as testing the airfoils when moving through the undisturbed atmosphere. There is no local force generator in the atmosphere to initiate airflow. There is no airflow; there is no reduction in pressure above or below the airfoil (from airflow) to produce pressure differentials to produce lift. There is no streamline, linear momentum, directed or ordered motion in the undisturbed atmosphere. Since the air molecules are not flowing, there is no velocity to determine so to figure out how much the pressure is lowered due to the velocity of the air.
The fourth: water and air being fluids are both incompressible and inviscid, which is obviously not true! Water is definitely incompressible, while air is almost infinitely compressible at the pressures Aeronautics is usually dealing with, and both water and air have viscosity, which increases decreases with changes in pressures and temperature.
We will be conducting experiments to determine the validity and invalidity of many of Fluid Dynamics stated relationships, laws and premises. Watch for these coming up on our website shortly.
The effort to produce lift by cambered airfoils The Acronym FOTAP (Fallacy Of The Assumed Premise) describes the aero engineering's problem: assuming Bernoulli's Principle to be true. The field of aero engineering has been built on false premises. Mathematical models and computer generated proofs of the accuracy of engineering's design and projects are only as valid as the premise on which they are based. Coefficients (corrections from computer generated capabilities versus actual tested performance) abound. When designing an airfoil to produce lift a knowledge of how lift is achieved is of vital importance (Lockheed took a graphic artist's drawing of an airfoil profile for the design of the P-38 wing. This was proportionally enlarged to provide the engineering basics for the Constellation wing, from the book "Shape and Flow".) If the design engineer believes that higher velocity above the upper surface from the highly cambered airfoil and the lower velocity along the lower surface from the lack of lower camber, and designs an airfoil accordingly, the Roof Top airfoil as reported in the Journal of Aircraft, Sept-October 1970 may be an obvious solution.
Liebeck and Ormsbee Rooftop Airfoil Profile FOTAP #1 To correct this error and clarify the true principles in the production of lift is the purpose of this research. Proof Cambered airfoils do not produce lift a la Bernoulli. |
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We constructed an airfoil as illustrated above and balanced it at the mid-point of the airfoil. We then placed pivot pins on both sides of the airfoil so that it could rotate clockwise and counter clockwise freely on these pins. The Center of Pressure (maximum camber point) is quarter chord leading to trailing edge of our airfoil, the center of gravity being midpoint of the airfoil, and about 1 inch to the rear of the center of pressure. We then placed the airfoil in the wind tunnel airflow, locked the pivot pins so that the airfoil would not be moved from its position by the airflow, and turned on the blower to our wind tunnel. With the Center of Pressure (C.L.) point 1 inch forward of the center of gravity (C.G.), lift generated by the air flowing over our airfoil should cause the airfoil to rotate in a counter clockwise direction and the leading quarter of the wing should rise. The greater the air flow, the more lift would be produced, and the greater the upward force exerted through the center of pressure on this mono element airfoil. Increased velocity-reduced pressure a la Bernoulli, right? See video by clicking here Unfortunately, the test didn't turn out that way. With the airfoil set at 0 degrees angle of attack, and the blower to the wind tunnel turned on, the airfoil would invariably and immediately rotate the leading 1/4 chord of the airfoil down! When we set the airfoil initially at 5 degrees angle of attack, the result was the same. We inverted the airfoil in the wind tunnel and the airfoil now rotated the leading 1/4 of the airfoil up! With the airfoil set as initially, we measured the down force at the leading edge at maximum air flow, at 1/ 3/4 oz. When we set the angle of attack just above 5 degrees the airfoil would remain where we had set it as the force diverting the air upward was the same as the force diverting the air downward. See the video by clicking here . When Burt Rutan's Voyager aircraft was being prepared for take-off, Dick Rutan (pilot) stated when he added the last extra fuel to the Voyager the outer wing panels drooped so that the wingtips were only about 18 inches above the ground. As the Voyager was accelerating down the runway for take-off and just before Rutan rotated the Voyager to take-off angle of attack, the cambered wings, instead of providing lift as the velocity of the Voyager increased, actually forced the outer wing panels down even farther so that the wing tips were touching the ground! After rotation of the Voyager to take-off attitude, the outer wing panels (now that they were producing lift) rose up so that the wingtips were probably 10 ft. above the ground. Burt Rutan had the wings of the Voyager on backwards and upside down! See video here: MPEG Movie Clip Real Media movie Windows Media Our aircraft would perform better if the trailing edge and the leading edge of wings were reversed and the camber was on the bottom at the rear of the wing. As usual Aero Engineering has the wings on aircraft upside down and backwards.
FOTAP #2 Fluid flow (air) in the wind tunnel is the same as fluid flow in the atmosphere- that is, testing an airfoil in the wind tunnel is the same as testing an airfoil in the atmosphere. This is simply not true and we will prove it! We checked the Overpressure (Head Pressure), Siphon Pressure, Dynamic Pressure and Air Pressure in our wind tunnel at 73.3 feet/sec airflow. Then we moved our test equipment into our vehicle and again checked for the same values by moving our pressure taps (ports) through the still atmosphere at the same 73.3 feet/sec Velocity. Since our Manometer was zeroed to atmospheric pressure, if we were indicating the actual air pressure the Manometer would show no change for the atmospheric pressure hadn't changed just because we were moving our pressure tap (port) through the air. Of course, our test equipment showed the same indications we had received in the wind tunnel. This has led Aero Engineering to postulate testing an airfoil in a wind tunnel is the same as moving the airfoil through the air, which is just not true! There is no local force generator in the atmosphere to initiate airflow, there is no airflow, there is no reduction of pressure above or below the airfoil to produce pressure differentials which can produce lift. There is no streamline, linear momentum, directed or ordered motion in the undisturbed atmosphere. Since the air molecules are not flowing, there is no velocity to determine so as to figure out how much the pressure is lowered due to the velocity of the air.
FOTAP #3 P1V1 = P2V2 = a Constant Our
research took us back to Bernoulli and Aeronautical Engineering's
application of the Bernoulli Principle. In Aero thinking, the
cambered upper surface of the airfoil produces higher airflow
velocity than the lower airfoil surface. (See Russ Cummings
answer to our paper on The Optimization of Lift) According to
their application of the Bernoulli Principle (P1V1=P2V2) lower
air pressure above the airfoil and higher air pressure below the
airfoil produces lift directly! THIS CONCEPT IS FALSE! Air
(fluid) flows from higher pressure to lower pressure. The
pressure gradient determines the velocity of the airflow; the
greater the pressure gradient, the greater the airflow. The air
velocity is caused by the pressure gradient and is not the cause
of the lowered pressure! Once the fluid (water) was moving
Bernoulli's standpipe also indicated the negative siphon pressure
as the connection of his standpipe to his flow pipe extended well
into the water flow instead of how he had pictured it in his
report of his experiment (Hydrodynamica). See our Bernoulli's
Experiment with Variations in the Optimization of Lift. In the
formula P1V1=P2V2, when P1=P2 the velocity would be zero at any
pressure!
FOTAP #4 Aero
engineers also state that the pressure of the supersonic flow of
exhaust gases from a jet engine at maximum power approaches
absolute zero, when they are really measuring the siphon pressure
created in their pressure tap by the supersonic and extremely
high dense flow.
FOTAP #5 Water (liquid) and air (gas) are both fluids and their flow patterns are controlled by the same laws. Aero
Engineering: Aero
Engineering says that fluid flow is inviscid and incompressible
(unable to be squeezed). This was postulated to ensure in the
Aero mind that the airflow at the stagnation point which flows
over and the airflow which flows under the airfoil would reach
the trailing edge at the same time. Actually liquids are
basically incompressible with varying viscosity and air has very
little viscosity and is almost infinitely compressible at the
very low pressures encountered in velocities below Mach one.
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The design for best L/D for the #2 accelerating airfoil was 15°. Using a higher rate of acceleration could have given a higher L/D only increased testing will determine this. Even at negative angles of attack, this airfoil produced lift with no detectable drag. The airstream velocity measurements were made at best L/D (lift over drag) at 15° angle of attack. HOW AN AIRFOIL PRODUCES LIFT Aero Engineering formulas: In 1939 L=Co. of lift X Area of wing X velocity squared in mph. In the 50's L=1/2 density of air X area of wing X velocity squared in mph X coefficient of lift. As an Aero Engineering designer, how do these formulas guide one as to optimize the lifting potential of an airfoil? To get more lift,
We know how to increase the velocity and the area of the wing, but how to increase the coefficient of lift? (The coefficient of lift is merely a measure of how much the estimated lift the wing will develop v/s the experimentally tested lift as measured. Since this is how far off the computations are as to the real lift produced an increase in the coefficient only indicates more error in the guesstimate!) Secondly, adding power to increase the velocity increases lift to the square of the velocity but why? The pilot can also increase the angle of attack and produce more lift but this factor is no where in the formula! Thirdly, increase in wing area will sometimes produce more lift but the question is which way are we to increase the wing area? For instance a wing with 40 ft. wingtip to wingtip (wingspan) and 8 ft. average leading edge to trailing edge of the wing (chord) will produce an airfoil area of 320 sq. ft. but an average wingtip to wingtip (wingspan) airfoil of 8 ft. and a 40 ft. (average) chord will also produce an airfoil of 320 sq. ft. but produce practically 0 lift! This
is the way a wing is generally designed: The
average chord of the wing X the wingspan = the area of the wing.
The weight of the plane divided by the area gives the wing
loading. Two 20 ft. wings (one 20 ft. on one side and one 20 ft.
wing on the other) may only have a 20 ft. wingspan in a highly
swept wing plan. Other problems Aero formulas fail to provide answers for. Inverted
flight. The
helicopter The
answer: The camber built into the helicopter rotor blades
provides much drag but no lift! In fact until the angle of attack
is increased the rotating blades produce only down loads! So how does an Aero Engineer handle all these variables in the formulas for lift? They don't! Design for airfoils is a "guess and test" program! Since their ideas of how lift is produced by increased velocity/lower pressure through the throat of the venturi a la Bernoulli, etc. this is the best they can do, and trying to optimize lift by their formulas produces the Top Hat airfoil fiasco promulgated by the two Aero Genuises referred to in Aero Blunder #2. So how does an airfoil produce lift as described in mathematical terms? The force the airplane exerts on the still air is the result of its accelerating the air downward. The equal and opposite reaction to the downward force we call lift. Using Sir Isaac Newton's laws of motion- F=MA force in lbs = Mass of air in Slugs X acceleration in ft./second To determine the mass we must determine the volume of air accelerated in one second X the density of the air. Volume equals height X width X length For height we use the air above and below the wing that is accelerated downward. (air accelerated forward produces induced drag) For width we use wingspan in ft. endplated. Without endplating wingtip losses must be subtracted from total width to determine air accelerated. For length we use the velocity of the airfoil in ft/second. Multiplying the volume by the air density, .002378 slugs per cu. ft. gives us the mass accelerated/second. Determining the Acceleration The rate of acceleration (like gravity - 32ft./sec/sec) is controlled by the length of the wing chord, the angle of attack, and the velocity of the airfoil through the air. The longer the wing chord the more the air will be either accelerated or displaced downward at any given angle of attack. (Increasing the Chord also increases the area of the wing) Doubling the velocity doubles the rate of acceleration (and mass of air accelerated) so the lift increases to the square of the velocity.
Running the numbers on the F4U Corsair. This is an example of how lift is determined. Numbers when quantified experimentally will be close to those used. Wingspan
41 ft. Empty wt. 8,942 lbs. T.O. & Climb sp. 75 kts. / 90 mph
/ 135 ft./sec. Taking
off at Max wt. numbers. Angle of attack 15 degrees, Flaps down 45
degrees, 75 kts. velocity Cruising
at max wt. Cruising speed 180 mph Angle of attack 7 degrees
positive There are two types of wings, the "Barn Door" displacing or diverting wing and the Accelerating wing. The
Barn Door displacing or diverting wing. (also referred to as the
"planing wing") With the diverting /displacing Barn Door airfoil, the air, instead of being accelerated downward, becomes a planing surface for the barndoor airfoil to ride on, and the air moves spanwise around the wingtips causing wake turbulence, upward around the trailing edge causing an upflow of compressed air (yes, air is compressed) and is carried forward along the under surface causing much drag, especially when flaps are lowered. With 10 degree flaps extended the displacing or diverting wing is similar to the accelerating wing. THE ACCELERATING AIRFOIL The leading edge is sharp with no stagnation point or leading edge radius to provide drag. The rate of acceleration is very low - 1 ft. per 12 ft. of Chord length but continuously accelerating the air downward at the same rate to the formula Dy=1/2 Ay X velocity squared. As the wing continues moving through the air, since the rate of acceleration is gentle but continuous, no detectable drag develops, and since the air is being continuously accelerated downward after the wing passes no upward movement of the air occurs behind and above the Trailing Edge. Wing tip plates preventing the spanwise flow of the accelerated air below and above the wing completes the efficiency of design of the accelerating airfoil. For high speed flight the accelerating portion of the airfoil is retracted (like flaps) and a very low accelerating airfoil results. At slow speeds, a relatively small volume of air is given a very large acceleration, and at high speeds a very large volume (the length factor in the volume equation equaling the high velocity) is given a very low acceleration to keep the airplane flying. CONCLUSIONS:
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