Author Topic: Wing stress  (Read 6106 times)

Offline nrshida

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Re: Wing stress
« Reply #75 on: August 25, 2013, 03:44:36 PM »
Because the Spitfire is taking 6 Gs of force in a 3 G turn due to its wings flexing and the Fw190A is taking 3 Gs of force in a 3 G turn due to its wings not flexing.

Ah. Pure genuis. I'm totally convinced.

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Offline Gaston

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Re: Wing stress
« Reply #76 on: August 28, 2013, 02:12:29 PM »
 

   If the wingtips are raised fast, or slow, this will affect the amount of energy present: This is irrelevant to the discussion of sustained turns...


  Gaston

  P.S. Hitech did not address what he meant about me not taking into account the direction of the forces.

  

  I should have said "Power" instead of "Energy" in the above sentence, since time is involved...

  Also in a turn, I suggested all the forces are equal to zero, which is true, but I forgot to add that if there is no Power "into" the turn, then there is no turn... I was wrong to say it this way, and there is of course Energy and Time involved in a sustained turn, not just Force: Force is holding the wings bent, but Power moves the aircraft up into the turn continuously while turning...

  I think I have figured out what Badboy and all the others fail to understand: You guys assume that for a heavy small wing aircraft to have more "Power" available to turn, vs a light big wing aircraft, it requires "added Power"...

  There is no "added Power" in my theory: To think that is to show you haven't read much of what I said...

  In my theory, all the nose-driven prop types lose turning Power compared to what is theoretically available. They are all losers, so there is no excess turning Power...

  This is why, despite a lesser climb rate and acceleration, and a minuscule 5% wingloading advantage (at 33.1lbs per sq. ft., compared with the Spitfire XIV's 35.1 lbs per sq. ft), the Vampire Mk I gains 25% in turn time per turn vs the Spitfire Mk XIV... (It reverses a tailing Spitfire XIV in four 360° turns)

  Let me re-iterate this: An aircraft with less Power-to weight (thus with less acceleration and climb rate) and a 5% wingloading advantage, will display a 25% advantage in turn time in low-speed sustained turns over a Spitfire XIV... How does that square with your calculations?

  The reason for the above is that all the low-wing nose-driven prop types (of some weight and power at least) lose turning Power compared to what is available to similar straight-wing jets. My contention is that some of the prop types lose less, some of the prop types lose more. There is nothing that involves "extra" turning Power here...

  The real problem, with my idea, is that there is a requirement for an extra lift Force to compensate for the huge lift Force loss needed to stabilize the nose thrust location higher vs the trajectory. Once the nose is lifted to the new AoA, there is no movement to keep it there: Just Forces.

  The problem of this extra lift Force is that it seems to mean there is more lift Force available in turning flight than what is seen in wind tunnels: This extra Force can't come from nowhere: For a wing to maintain easily a powered nose at a more upward angle, there is apparently extra Force to be found in curved airflow, just like your arm will find extra Force pulling on a pulley... How it does that is the real problem...

  If the object is too heavy and the pulley doesn't lift it, your effort remains just Force, but that doesn't mean you don't lose your available physical Power pulling on it... Or that you would not lose more available "Power" for applying the same Force with a smaller pulley... Well the Spitfire has a smaller pulley, so it loses more lifting Power than the FW-190A, which doesn't mean the FW-190A ever "gained" anything...

  The "curved airflow pulley" is here to help hold the nose up into the turn, which contributes no Power to pulling the aircraft up into the turn: On the contrary it subtracts from it... I don't think there is any physical law that says that a Force cannot reduce the effective motion of a given Power...

  The Fw-190A certainly doesn't gain 25% per turn on a Spitfire Mk XIV, so it would still get creamed by the Vampire... Its turn Power potential is way below the Spitfire Mk XIV, but it just doesn't lose turn Power potential, to waste it on Force, as much as the Spitfire does.

  Gaston

  

  
« Last Edit: August 28, 2013, 02:23:58 PM by Gaston »

Offline hyzer

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Re: Wing stress
« Reply #77 on: August 28, 2013, 02:35:59 PM »
I think the answer to how the theoretical structure known as a skyhook has finally been discovered. It is now obvious to me it must work on the "curved airflow pulley" principal.
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Offline Karnak

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Re: Wing stress
« Reply #78 on: August 28, 2013, 02:53:01 PM »
DH Vampire is a jet, Spit XIV is a piston engined fighter.  How are you calculating power to weight ratio for each and at what speed are we talking about?
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Offline hitech

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Re: Wing stress
« Reply #79 on: August 28, 2013, 03:31:59 PM »
 
  Also in a turn, I suggested all the forces are equal to zero, which is true, but I forgot to add that if there is no Power "into" the turn, then there is no turn... I was wrong to say it this way, and there is of course Energy and Time involved in a sustained turn, not just Force: Force is holding the wings bent, but Power moves the aircraft up into the turn continuously while turning...
  Gaston

 

You may wish to tell glider pilots about this theory so they make sure to never try and turn.

HiTech
« Last Edit: August 28, 2013, 05:58:18 PM by hitech »

Offline morfiend

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Re: Wing stress
« Reply #80 on: August 28, 2013, 05:54:23 PM »
You man wish to tell glider pilots about this theory so they make sure to never try and turn.

HiTech


  :rofl :rofl :rofl

  But what about the tow rope?  It has to input some power to the glider.....


   When I was a youngster my Dad would say "you cant shoot pool with a rope"   I think I finally understand what he meant.


     :salute

Offline Jabberwock

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Re: Wing stress
« Reply #81 on: August 28, 2013, 06:00:52 PM »
Hey Gaston, I see that your grasp of the mechanics of flight are as solid as they've ever been.

For those interested, here are a few extracts from the tests, via a post here a couple of years back

Quote
Turning Circles: The Vampire I is superior to the Spitfire XIV at all heights. The two aircraft were flown in line astern formation. The Spitfire was positioned on the Vampire's tail. Both aircraft tightened up to the minimum turning circle with maximum power. It became apparent that the Vampire was able to keep inside the Spitfire's turning circles. After four or five turns the Vampire was able to position itself on the Spitfire's tail so that the deflection shot was possible. The wing loading of the Vampire is 33.1lbs per sq. ft. compared with Spitfire XIV's 35.1 lbs per sq. ft.
...The Vampire will outmanoeuvre the Spitfire type of aircraft at all heights, except for initial acceleration at low speeds and in rolling.
... The Spifire XIV used in the comparison trial was a fully operational aircraft fitted with a Griffon 65, giving 2,015 h.p. at 7,500 ft. Vampire I had an operational take-off weight of 8,800 pounds, powered by a de Havilland Goblin 2 turbojet, developing 3,000 pounds static thrust."
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