Wright Bros question

Discussion in 'Hangar Flying' started by jgnunn, Feb 5, 2007.

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  1. Feb 5, 2007 #1

    jgnunn

    jgnunn

    jgnunn

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    I am sure someone knows the answer to this:

    why is it that they ended up with a biplane, when their only comparison at the time were monoplane birds?

    and how'd they end up with the canard design?
     
  2. Feb 5, 2007 #2

    orion

    orion

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    As there were very few aero design technical references in their day (and most of those questionable) the Wrights undertook an extensive database development program through which they determined the constraints for many of the critical design points they were working to achieve. One of those was sort of a back door approach to determining the achievable speeds through available horsepower. The drawback of the day of course was that the available power was very low (12 hp) but the power plant weight was quite high (~400 lbs). Their glider tests (some of which were of monoplane design) provided them with a goal for wing loading but structural and size requirements proved that the only way to meet all the variables was to utilize two wings.

    As one might guess, the process was quite inexact, especially as performance and structure were concerned. Given the number of recent unsuccessful attempts at recreating the Wright Flier, it must be concluded that a certain amount of luck was involved in getting to their achievement.. For instance, one thing that was discovered a few years ago was that if they were able to get as little as three more horsepower out of their engine, the airframe would have most likely twisted and collapsed in upon itself during take-off or shortly thereafter.

    Regarding the canard, I have heard several theories about this, usually from folks who have never read the Wright's notes. The actual reason for the canard however was very simple - they wanted structure in front of the occupant just in case the craft came in nose first - in other words, the canard was a sacrificial bumper.
     
  3. Feb 5, 2007 #3

    Norman

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    There are other reasons too. It's important to remember that although many of the analytical methods that underlie modern structural engineering were known by the late 1800s but there was still a lot missing and what was available was quite cumbersome. The result was that shortcuts were taken and compensated for with huge safety margins (for instance the Brooklyn bridge is 5 or 6 times heavier than it needs to be). Before the '20s designing light, high aspect ratio, cantilever beams was a risky business. Many of the early monoplanes collapsed from beam-column failure and nobody could explain why so before W.W.I some countries actually passed laws against selling them. The Australian aviation researcher, Lawrence Hargrave, had invented the box kite in the early 1890s. By the time the Wrights got into it several years later everybody in aviation knew about the structural advantages of biplanes and several were building multiplanes (although without much success). In May of 1900 they contacted Octave Chanute to praise him for an article he had written (a geek fan letter?). Chanute was a civil engineer and is credited with inventing strut and wire interplane bracing. Although his own gliders were never very successful his encouragement of the Wrights was probably very important to the development of powered flight. Or at least that's what they told him.
     
  4. Feb 5, 2007 #4

    Topaz

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    I've got a couple of really nice books on the Wrights' development program, one written by one of the brothers as part of a lawsuit.

    I can't recall the specific reasons for a biplane, other than what Orion and Norman say sounds familiar, but one of the stated reasons for a canard was simply to allow the pilot to see the position of the surface, which they thought would aid in control of the aircraft.

    That stemmed from their early testing in smaller gliders, and since the Wrights were actually quite conservative in their development program, they stuck with the basic configuration and simply scaled it larger for their powered aircraft.
     
  5. Feb 6, 2007 #5

    Norman

    Norman

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    Chanute's writings

    Oops :p: this is the link I meant to give for Octave Chanute. Of particular relevance to this thread is the picture of the 1896 Chanute-Herring glider. It's also amusing that this site appears to be hosted on the Mississippi State University Psychology department server:ponder:
     
  6. Feb 9, 2007 #6

    wsimpso1

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    In their notes, they said that they also liked having the elevator out front so that they could see it in flight, in order to learn how to fly the machine. They were concerned about intuitive learning right from the beginning...

    I actually heard someone postulate that they were trying to get lift out of the canard too, but that appears to be false. Their original gliders and airplane had symmetric uncambered elevators but the wings were cambered. They configured their original gliders and then the first powered airplanes with the cg about where they figured the center of lift was, and all that they intended the elevator to do was provide pitching moment. Aero loads on the elevator would have been small no matter whether the elevator was forward or aft. That meant that the 1902 glider and 1903 Flyer were unstable in pitch. They actually figured out later that shifting the CG forward allowed the airplane to become stable in pitch and be flown without those very many control inputs they had been using.

    Billski
     

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