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Were the Wright Brothers in Newton's camp?

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Have you ever read the Wright Brothers' Patent for a Flying Machine? On Page 1 from Lines 37 to 43 they tell us that the machine is supported in the air by reason of the contact between the air and the undersurface of one or more aeroplanes (their term for 'wings'), the contact surface being presented at a small angle of incidence to the wind"

Page:Wright-Patent-US-821393.pdf/4 - Wikisource, the free online library

 

That description of how a wing generates lift is proposed by those who say that Lift is an effect of Newton's Laws of Motion.

 

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The other camp - Bernoulli's Boys, propose that Lift is an effect of the relative velocities of air passing under or over a wing.

 

1539238331289.thumb.png.f55f815e77d23252978d00d53c0f73ae.png

 

Given that the Wright Brothers were practical mechanics, and not theoretical physicists, I doubt that they had a clue 'how' an "aeroplane" produces lift. They just knew from their own experiments (and correspondence with Lawrence Hargrave) that a wing, angled slightly above the horizontal and faced into the wind could be used to raise a structure into the air.

 

It is interesting to note that the Wright Bothers' patent was not about the design of and aeroplane's wings and fuselage per se, but about the means to control the position of the wings in the airflow, i.e., turning, rising and descending.

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In other threads this has been discussed in some detail. I am in the Wright camp, lots of aerobatic aircraft fly quite well with symmetrical wings. If strength was not an issue planes could fly with paper thin wings.

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I didn't want to start that Newton -v- Bernoulli thing again. It's just that I saw that description of Lift according to the W B's and thought it would be worth quoting. Also, it was a chance to give people access to the patent application as a matter of interest.

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You can make a brick fly if you apply enough force. A lot more lift is produced for an equal amount of thrust if the wing is cambered. Aerobatic planes are hugely powered for their size, so they will fly quite well (in any orientation) with a fully symmetrical airfoil. Missiles are much the same.

My argument is that's it's not a "Newton vs Bernoulli" thing, it's a combination with any form of wing somewhere on the spectrum.

Edited by Guest

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The thing their plane(s) had over the others initially was the ability to control the plane in the roll axis directly and not as a secondary effect of rudder.. Static plus dynamic pressure is a constant has little meaning to the average pilot except at exam time. If some surface of your plane deflects air, the structure will react to it by being forced in the opposite direction. Air stays still or moving in a straight line unless something acts on it. That' it put simply so the pressure on the inside of a curving airflow will be less than on the outside, or it won't be curving. Pressure always acts "normal" (perpendicular)

to the surface. Air has viscosity too,. But that gets more difficult. A "lifting" airfoil shape will produce positive lift at negative angles of attack .Nev

Edited by Guest

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The angle of incidence has a direct bearing on lift and in my opinion the shape of the wing has more bearing on reduction of drag than on lift.

I could be wrong, or I could just start an argument.

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I don't think any of that statement Yenn is likely to be challenged particularly but the L/D ratio is just about everything to do with how well a plane performs. You couldn't start the design without having some grasp of the capability of the wing to support the aircraft in flight.

Having a suitable powerplant was also the essential element that enabled sustained flight. Their particular engine wasn't that good in the power and power/weight ratio department and was soon improved. Otto Lilienthal's gliders were quite developed so a power plant was the logical progression. Curtiss offered to build one but the Wrights wanted it to be in house.. An employee called TAYLOR was the person who designed and built the engine used. Nev

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I think the technical aspects of how a wing etc works is important to a designer/builder but to the average Pilot it matters little (high performance excepted) - a basic understanding is certainly helpful but detailed debate is really not that relevant on low performance aircraft.

 

I am reminded of an incident many years ago when I fronted up for a CHTR and informed the manager that I had never flown the particular type before (was SE) and was told it is just an aeroplane, push the knobs to the firewall and pull back on the stick and it will fly like the others. I accept it was not desireable, and probably wouldn’t happen these days, but guess what he was right.

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You can make a brick fly if you apply enough force. A lot more lift is produced for an equal amount of thrust if the wing is cambered. Aerobatic planes are hugely powered for their size, so they will fly quite well (in any orientation) with a fully symmetrical airfoil. Missiles are much the same.

My argument is that's it's not a "Newton vs Bernoulli" thing, it's a combination with any form of wing somewhere on the spectrum.

 

I am with you Marty. It has to be a combination of Bernoulli and Newton.

 

The CH701 and Savannah aircraft have fat "high lift wings" and that is Bernoulli at work. But, with leading edge slats (701s) OR vortex generators (Savannahs) a large angle of attack is possible putting Newton to work.

 

Bernoulli and Newton make a great partnership!

Edited by Guest

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The chapter on Lift in the Fly Better books by Noel Kruse describes it well. Effectively, the AoA and chamber of the wing bends the airflow creating a low pressure area above the wing (lift). This area of low pressure causes the airflow to speed up (opposite to what is commonly taught). Engineers used Bernoullis' theorem to measure the increased dynamic pressure of the airflow created from the low static pressure above the wing to test different shapes of wings, and at some point this was used to explain how lift is created rather than a resultant of the creation of lift.

 

Given that the Wright Brothers were practical mechanics, and not theoretical physicists, I doubt that they had a clue 'how' an "aeroplane" produces lift. They just knew from their own experiments (and correspondence with Lawrence Hargrave) that a wing, angled slightly above the horizontal and faced into the wind could be used to raise a structure into the air.

 

I believe that's a bit rough. The Wrights understood lift better than anyone else at the time. That's how they were able to develop an effective method to control their aeroplane (wing warping) as well as understand the requirement for a rudder. They also managed to design a propeller with an efficiency similiar to modern propellers with out any previous data to work with.

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The Wrights understood lift better than anyone else at the time. That's how they were able to develop an effective method to control their aeroplane (wing warping) as well as understand the requirement for a rudder. They also managed to design a propeller with an efficiency similiar to modern propellers with out any previous data to work with.

 

The general design of a propeller had been known for close on 2000 years before the WBs [Propeller (aeronautics) - Wikipedia]. Longer if you want to include the aerofoil shape of a returning boomerang. The twisted (aerofoil) shape of an aircraft propeller was pioneered by the Wright Brothers. While some earlier engineers had attempted to model air propellers on marine propellers, the Wright Brothers realized that a propeller is essentially the same as a wing, and were able to use data from their earlier wind tunnel experiments on wings, introducing a twist along the length of the blades. This was necessary to maintain a more uniform angle of attack of the blade along its length.[17] Their original propeller blades had an efficiency of about 82%,

 

 

The chapter on Lift in the Fly Better books by Noel Kruse describes it well. Effectively, the AoA and chamber of the wing bends the airflow creating a low pressure area above the wing (lift). This area of low pressure causes the airflow to speed up (opposite to what is commonly taught). Engineers used Bernoullis' theorem to measure the increased dynamic pressure of the airflow created from the low static pressure above the wing to test different shapes of wings, and at some point this was used to explain how lift is created rather than a resultant of the creation of lift.

 

That puts you into the Bernoulli camp. Modern writings agree that both Bernoulli's principle and Newton's laws are relevant and either can be used to correctly describe lift . It is not the Bernoulli principle itself that is questioned because this principle is well established (the airflow above the wing is faster, the question is why it is faster).

 

How an an anti-gravity force is produced by an aerofoil is probably one of those questions that does not have an answer that can be expressd in simple terms. It is akin to religious faith. We know an aerofoil works, but we don't know how.

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I wouldn't categorize it as an anti gravity force. Gravity doesn't come into it except to allow the atmosphere to stay there for us to breathe and fly in (amongst other things). Suitable parts of the effect are called LIFT which is ok in level flight to explain why the heavier than air machine stays in the sky. I explained that affecting where air goes requires a pressure differential. to push it there or curving it.. Even the atmosphere 's winds behave the same way.. If it's circulating, partly or completely the low pressure is on the inside of the parcel of air being considered.. AIR always flows from higher to lower pressure In a dynamic situation the density has a direct effect in the lift (and drag) equation.

The equal transit of the upper and lower air is INCORRECT. That was used to explain the lift theory but is easily proven wrong. The airflow also rises ahead of the Lift generating wing and usually separates from the boundary commencing at about the thickest part of the airfoil shape.

The sophisticated aerodynamics of the blades of a Jet engine are a critical to it working at all. Nev

Edited by facthunter
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"Anti-gravity" is often used colloquially to refer to devices that look as if they reverse gravity. An aerofoil (wing) is such a device. If air does not pass over a wing, no lift is produced. If air does flow, a Force with a vector component opposite to the vector component of gravity towards the Earth is produced. The difference in the magnitude of the Lift vector and the Gravity vector allows the aircraft to go up, down, or not change position vertically.

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The twisted (aerofoil) shape of an aircraft propeller was pioneered by the Wright Brothers. While some earlier engineers had attempted to model air propellers on marine propellers, the Wright Brothers realized that a propeller is essentially the same as a wing, and were able to use data from their earlier wind tunnel experiments on wings, introducing a twist along the length of the blades. This was necessary to maintain a more uniform angle of attack of the blade along its length.[17] Their original propeller blades had an efficiency of about 82%

 

Exactly. Pretty good for a bunch of blokes who

I doubt that they had a clue 'how' an "aeroplane" produces lift.

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That puts you into the Bernoulli camp.

 

Then you have misunderstood me.

 

(the airflow above the wing is faster, the question is why it is faster).

 

That is exactly what I tried to explain. The Fly Better books explain it better than I can, or have time to.

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Lift in a steady climb with power is less than weight. In a glide with power off it's still less than weight. Lift is defined as a force at right angles to the flight path generally so I adopt that. Weight is mass acting vertically, under gravitational force. All states are in equilibrium for analysis.

There appears to be so much confusion on this matter perhaps a new post is required. Nev

Edited by Guest

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One of the best books on aerodynamics I have come across is See How it Flies.

 

The analyses of airflow over a wing are very detailed and sometimes get into some complex formulae - but the basics are fairly easy to grasp with the aid of clear "wind tunnel" diagrams.

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Low pressure above the wing can only be 14.7329334 pounds per square inch.

I have no idea what max pressure below the wing could be. but suspect more than my work-shop compressor, 200psi.

spacesailor

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...Gravity doesn't come into it except to allow the atmosphere to stay there for us to breathe and fly in (amongst other things).

Which raises another interesting question - what would aircraft look like in lower gravity? It seems likely that mankind will colonise both the Moon and Mars within the next century, barring nuclear accidents and unmitigated climate change.

Mars gravity is 38% of Earth's, and the atmospheric pressure at surface is about 60% of Earth's at MSL. So with lower weight but also lower "air" density, I'd think that aircraft could have less wing area and fly a hell of a lot faster... depending on power source. Electric-driven props with more pitch and broader blades to handle the thinner atmosphere? No point having jets, there's not much oxygen.

The moon might be even more interesting. With gravity only 1/6th of Earth's, but air pressure within habitat domes being roughly the same, very small hang gliders could be used to scoot from one side to the other. Maybe something even resembling the fins of fish.

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In other threads this has been discussed in some detail. I am in the Wright camp, lots of aerobatic aircraft fly quite well with symmetrical wings. If strength was not an issue planes could fly with paper thin wings.

Yes, the Newton camp argue that a symmetrical wing flies so the Bernoulli theory is wrong. The airflow though, is not symmetrical.

My understanding is that it is more complex than just one or the other, but both apply.

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Which raises another interesting question - what would aircraft look like in lower gravity? It seems likely that mankind will colonise both the Moon and Mars within the next century, barring nuclear accidents and unmitigated climate change.

Mars gravity is 38% of Earth's, and the atmospheric pressure at surface is about 60% of Earth's at MSL. So with lower weight but also lower "air" density, I'd think that aircraft could have less wing area and fly a hell of a lot faster... depending on power source. Electric-driven props with more pitch and broader blades to handle the thinner atmosphere? No point having jets, there's not much oxygen.

The moon might be even more interesting. With gravity only 1/6th of Earth's, but air pressure within habitat domes being roughly the same, very small hang gliders could be used to scoot from one side to the other. Maybe something even resembling the fins of fish.

I think the atmospheric pressure on Mars is actually 0.6% of the pressure on Earth.

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The "reduction" of the ambient pressure above the wing can never be total (ie a vacuum) and the pressure below can be very high but only at crazy speeds. Above supersonic the air behaves differently to below. U/L's don't look like going there for a while, so generally we can regard the lift available from the curved section on the top to be greater than the "compression" effect on the lower surfaces at incidences that are positive,.. Manometer tubes will show local pressure but will be in a direction "normal, ((right angle)" to the surface where it's measured which is the way all pressure acts on a surface. Nev

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The "reduction" of the ambient pressure above the wing can never be total (ie a vacuum) and the pressure below can be very high but only at crazy speeds. Above supersonic the air behaves differently to below. U/L's don't look like going there for a while, so generally we can regard the lift available from the curved section on the top to be greater than the "compression" effect on the lower surfaces at incidences that are positive,.. Manometer tubes will show local pressure but will be in a direction "normal, ((right angle)" to the surface where it's measured which is the way all pressure acts on a surface. Nev

I' agree with this; supersonic, I have 400 page US Navy theory book that would make your eyeballs spin. Sub sonic, wing section design needed varies with the power to weight ratio of the aircraft.

 

In the Pipers and Cessnas of the 1950s two thirds of the lift was derived from the upper surface due to the Bernoulli effect and one third from the lower surface due to the force.

 

WW2 british bombers, which had low power to weight ratio had upper surfaces much more deeply curved than aircraft which only carried a few passengers. This was to maximise the Bernoulli effect.

 

Model aircraft have a huge power to weight ratio, and you could fly most of them if you replaced the aerofoil with a flat profile because at anything above about one third throttle the engine is providing enough power to make them fly on the bottom surface only. They can be quite unrealistic compared to a full size aircraft until to pull the throttle back to about 1/3, then they are quite realistic in how they need to be flown. Aerobatic aircraft are approaching this level of power to weight ratio, so Bernoulli effect is almost irrelevant.

 

Other areas where the Bernoulli effect is used are:

 

Refrigerators

A gas under compression is forced through a venturi where it has to go faster, lowering the pressure; lowering the pressure reduces the temperature, and each time the gas recycles through the venturi the temperature drops again until the desired temperature is reached.

 

I found my old BAK notes with a very good explanation of Bernoulli including the relationship between Kinetic Energy and Pressure Energy; I'll rewrite/draw them here of anyone wants.

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Your last reference is to a bootstrap machine where expanding air is repeatedly cycled P1V1/T1 is a constant is the universal gas equation. Very handy in these matters... Volume increases Temperature drops. and the converse is true. That's how a diesel engine ignites the fuel. Nev

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