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Were the Wright Brothers in Newton's camp?

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Isn't the equation along the lines of.

Total pressure is constant, therefore if dynamic energy goes up pressure energo goes down in proportion.

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I think we are dealing with exactly the same outcomes but expressed more esoterically with Bernoulli. In meteorology when air rises it cools adiabatically as the pressure drops and the "Parcel " expands it will cool. If you compress it, it will heat. Explaining it the way Bernoulli puts it you just have to accept the statement "static plus dynamic pressures are a constant"." I find that less enlightening than looking at it in other ways. I don't believe you lean to Newton or Bernoulli as if one is right and the other not right. It's more like what's fashionable at the moment to pass an exam or win a contest of some kind.. Newtonian Physics are very relevant to flying and understanding aircraft. Nev

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

 

You are entirely correct Octave, I didn't see the % sign and thought it was 0.6 of Earth's. That'd make lift even harder to come by.

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For my money both are exactly the same. An object produces a force equal to the mass change in momentum that it causes to the air, or fluid if we are talking about boat props. But try and work out the lift using the change in flow. To theoretically work out lift use the Dell operator around the wing. Very complex mathematics. However Bernoulli's theorem with a lot of factors to make a single instance of the equation work and you have the most appropriate equations work. There is a website that offers a two dimensional solution using the Dell operator mathematics. But even that is approximate, the three dimensions makes it much more difficult. I did three years of university mathematics and four years of engineering nearly 50 years ago and so the Dell operator is just a faint memory. 20 years ago I got the old books out. I was totally lost in how to do the mathematics. I just use the Bernoulli's equations with correction factors determined by wind tunnel testing.

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Designers have to have something to base a design on at the onset. Various formula's provide such a basis but don't explain a lot to your average Joe. Wind tunnels and smoke provide confirmation that the wing works and also the myths that abound are shown to be false by the visual evidence of particularly the interrupted smoke trails which show velocity. Scale effect and Reynolds number few ever master. It's true a pilot doesn't have to know all this but they are frequently put through various tests that perpetuate misconceptions. and may even act to lose an applicant job. At an interview in 1965 in response to explaining how a wing works I gave essentially what you have above "deflect a mass of air sufficient to cause a reaction equal to the aircraft's weight" and noticed the appalled look in the interviewers face, so said "Oh you want the one where static and dynamic are a constant"? Close call that's probably still happening today. Nev

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Newton's Third Law explains the force (lift) on the aircraft. Bernoulli (a reasonable approximation at low subsonic speeds) explains the distribution of that force on the surfaces of the aircraft. Check your frame of reference. It is very easy to inadvertantly swap to another frame without realising it.

You see an aircraft flying by. You know gravity is pulling it down so there must be a force (lift) opposing gravity. What do you see in the air around the aircraft? It is moving down behind the aircraft. Newton 3.

Now change reference to being in the aircraft. YOU CANNOT DETECT gravity. What you feel is the aerodynamic reaction force on the aircraft distributed according to Bernoulli. Obvious when you think about it as you can vary it at will by moving the stick back and forth.

 

Turbo's post as usual gets things hopelessly wrong.

Look up some pressure distributions over airfoils on the top and bottom surface. Most modern airfoils have reduced pressure on BOTH surfaces. It is the integrated difference that counts. The power to weight of an aircraft matters because if you have high power to weight you usually want the aircraft to go fast. To do that you want a thin small wing with low camber to minimise drag. If you have low power to weight and want to carry a load you want to minimise structure weight. This requires a thick wing with a lot of camber to minimise drag as you don't have much 1/2 rho V^2 to work with.

 

I'm not even going to get into the refrigerator theory. How did Enrico Fermi put it to an aspiring young nuclear physics student? "So bad it is not even wrong."

 

Human powered flight will be quite practical in underground caverns on the Moon if the air pressure is sea level Earth normal (forget the bubbles on the surface - micrometeorites and cosmic rays along with solar protons). The Moon will mainly be useful to strip mine for materials for O'Neill habitats where the solar power is 24/7 instead of being unavailable for two weeks at a time unless at the lunar poles on high peaks. Gravity is also what you want it to be on a space habitat. We simply do not know if anything substantially less than one g for long periods is viable for humans. We do know zero g isn't. This is one of the things that should have been done on the ISS but that experiment was cancelled in favour of high school science experiments and torturing astronauts in zero g.

 

"It seems likely that mankind will colonise both the Moon and Mars within the next century, barring nuclear accidents and unmitigated climate change."

The risk is more like regressing to a pre techological civilisation (horrible) because of people like Marty. Want to mitigate CO2 emissions? (pointless anyway). Build lots of nukes. Any else is hypocrisy.

BTW Marty the air pressure at the average ground level on Mars is 0.6% (6hPa) that of Earth sea level. There is also at least 20 times as much CO2 (95% of atmosphere) over every square meter of Martian surface as there is on Earth. It is very cold.

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Mike, none of my references are recent but some recent "surfing " of popular discussion of these matters shows me the hopeless lack of Basic Physics out there. I just cannot get over how wide of the mark some of the supposed educated responses that are offered can be.. Not just in the words but in the conceptual sense. In the subsonic (and significantly so) area not much new has been about since WW2. when the popularized Laminar flow concept was widely applied. Probably a bit inappropriately at times. My first reference was probably Kermodes "Principles of Flight" I think it was called. It's probably out there A C Kermode is the author from recollection . It's not in front of me. so I'm not sure. Nev

Edited by facthunter

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A very interesting and facinating topic to read on the forum, and I suspect, like all of us i have my own opinion of the wright brothers moterized box kite R&D development such as the VERY slight wing curvature being the result of forward air speed and angle of attack on an extremly flimsily supported steched fabric which once observed was replicated in design. Its just a shame that their interest in commercializing the concept almost completly ignored any credit of all of the R&D from around the world that they combined to get powered flight started. good reading on a wet sunday morning though, cheers Hargraves

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I wouldn't refer to it as a "motorized box kite" as it's a three axis controlled free flying, powered machine, with all balance, control and stability issues addressed which is a quantum leap from a tethered kite. They also self taught them selves to fly. It's not much of a jump from a glider though. Their inclination to indulge in extensive Patents and wait for the millions to roll in didn't help Aviation progress for a while, or their reputation .

France was probably one of the most "air travel" focused countries and eventually built the Wright Flyer under licence.. When it was exhibited and demonstrated eventually in France, they WERE in full acknowledgement of its superior control and maneuvering capabilities.. THAT is all about 120 years ago. Not long when you see what we have today. Nev

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I would agree on a two axis control system but alteratly bending either side of a very flimsy box kite wing design, would only Just qualify as a third axis control measure and was quickly realized as a major design fault and again I suspect was the R&D result of obseving the structure flexing of its own accord in earlier development, all good but, they did it, and thank Darwin they did eh. Cheers Hargraves

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I doubt that the WBs would ever deny that they "invented" the flying machine. They used all the prior knowledge of aeronautics to construct firstly an airframe, then a motive system. Their breakthrough was the development of a method to control the diversions of the flying machine from its intended path, ie roll, pitch and yaw control. Look again at the relevant lines (from about Line 45 on page One of the application). That clearly states that the patent is for a method of controlling these movements. The rest of the guff 'n' stuff relates to how they built the airframe to include their control method.

 

The concept of ailerons was an old one in aeronautical research. The modern aileron was invented and patented by the British scientist Matthew Piers Watt Boulton in 1868, based on his 1864 paper On Aërial Locomotion. I imagine that the WBs may have looked for a different method from ailerons on the basis of the weight such a system might add to a flimsy construction. As aircraft became faster, and the military need for maneuverability became a high priority, it was soon clear that wing warping did not work for those aircraft. Form follows function.

 

Here's a link to Boulton and his patent application: Matthew Piers Watt Boulton - Wikipedia

Edited by Guest

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The Wright brothers knew of the work of George Cayley, an Englishman who built a glider which was flown, long before the Wright brothers got airborne. I believe the pilot was his coachman, who gave up his job after the first flight, but i have also heard that it was Georges son who did the first flight. Whoever it was, his glider was controllable and he knew it needed a good engine and that is what the Wrights really made.

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Well other comparable aircraft did not have any roll capability other than rudder secondary effect and maneuvered much less satisfactorily than the Wrights demonstrated. That's clearly on the record. Wing warping works and structures coped with single fabric surface. I presume that system is what the Wright's patented. Curtis had to avoid copying it (stated in records) so used the later more used hinged ailerons. Some early ailerons only had down movement, so plenty of adverse aileron effect there. The wing warping would be an improvement on that.. They tended to do what birds did so that's actually not too stupid.

Wings not strong enough in twist will respond to aileron forces by giving an effect contrary to the aileron direction.. That undesirable effect has occurred with some modern U/L's that aren't stiff enough in the wing. The early motor was credited with only 16 HP. It was quite an odd design Fuel combusted in an anti chamber and prone to overheat. Engine on it's side, fuel dripping into the intake ports and hardly enough power to keep it in the air. Built and designed by an employee called Taylor . Curtis offered to supply an engine, but his offer was rejected. A more conventional all new upright 4 cyl but bigger engine was built in house soon after and the power was about 25 HP . A fair % increase..Nev

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facthunter, you are right about widespread ignorance of basic physics. Not confined to aviators unfortunately. Our politicians and bureaucrats wouldn't know the difference between a kilowatt and a kilowatt hour which will have disastrous consequences for Australia's electrical power system.

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I think the book FH refers to in post #34 may be A.C.Kermode's excellent "Flight without Formulae". I lent mine many years ago & never got it back, but as I recall it did an excellent job of explaining the principles of flight without complex mathematics.

 

Bruce

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The most interesting story that I was told about aviation mathematics was told in 1970 when I was at Uni. Early in the 20th Century (around 1915) aeronautical were working on the mathematics of fluid flow around a solid body, they were so proud of themselves determining all the mathematics using first principles and then published their research only to be informed by naval architects that they had developed the mathematics 20 years before. L ack of communications!

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The Wright brothers were pretty good scientists and engineers. They did experiments and tests and they corresponded freely with their peers. Hargave in Australia was one.

They were better scientists than Professor Langley, one of their many competitors.

I reckon the main test of scientific ability is whether you do tests and learn from the evidence so collected.

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I reckon the main test of scientific ability is whether you do tests and learn from the evidence so collected.

 

The scientific method involves:

 

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The problem with the WBs was their refusal to enter into communication with other aviation pioneers after 1903, and their dogged insistence on enforcing their patent, although we have seen in this discussion that there was much knowledge available from the work of mid-19th Century experimenters.

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OME, you are right as usual, but I still say that the Wrights were good scientists and better than their competitors. Not perfect, as you point out.

Their work on propellers shows a good example. Their propeller was way better at the time because of scientific testing.

Alas for lawyers and money and patents huh. This stuff was the bane of America and they lost their lead over it.

Universities today are being ruined by the same thing, so don't be too hard on the Wrights.

AND it is noticeable from your chart that a university degree is not necessary to be a scientist... bravo!

Edited by Bruce Tuncks

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Isn't the application of "Scientific Method" begun in infancy?

  1. Do I want a bicky?
  2. Where does Mummy keep the bickies?
  3. If I can open the bicky tin, I can get one for me.
  4. I just have to open the cupboard, grab the bicky tin and open it.
  5. I can open the cupboard, but the bicky tin is too high to reach. No bicky.
  6. Further refinement of the plan. If I climb up the shelves I can reach the bicky tin.
  7. Climbing up the shelves gets me to the bicky tin.
  8. If I want to get a bicky, I just have to open the cupboard and climb up the shelves to reach it.
  9. I won't tell Mummy that I can reach the bicky tin. She'll only go and hide it.

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That seems more like "RAT" cunning. The scientific method is a progressive series of checks and disciplines. You look for being wrong as you go. You don't assume you are right, and just press on. The result has to be completely repeatable. The experiment has to have controls so external factors outside of the consideration don't distort the outcome.

Getting back to the Flyer. It was not easy to fly being underpowered and had the usual canard oversensitive in pitch problem Also it had no keel surface, so if the wing got displaced by a gust or such it could sideslip rapidly and fall out of control if you didn't respond quickly with rudder. Nev

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