Airbus Invents Turning By Fuel?
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Cosmo
My point being that on T/O the same upward bending is experienced as in cruise, and at maximum values, why an empty wing? That also presupposes less than full Fuel on T/O. On landing, wheels on can create a serious down moment for the wing, so empty is good, and since some length of time has elapsed in flight, less fuel to stray away from centered mass any way. Not trying to argue, I don't see the logic of empty wings on T/O. Is Airbus concerned about weight in the wings whilst parked? If that's the case, why put tanks in wings in the first place.
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I appreciate your patience. Evidently Airbus values wing stress at cruise, but when on the ground, empty is better, even if a take-off produces the highest upward stress values in the flight. Alas, what do we do when all tanks are full? Also, with Fuel in the wings at take-off there is an inertia induced stability in Roll, Handy when close to the ground.
AF
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The patent is here
Hi folks. Paul Marks at New Scientist here. I wrote the Airbus patent news article to which this thread refers. I'll get the link to the patent put back in the original story (fell out somehow) but here you go anyway:
The US patent application is here: http://www.pat2pdf.org/patents/pat20090088911.pdf
If it has expired from the www.pat2pdf.org cache enter this patent number there: 20090088911
and it'll make you a PDF. What will they think of next?
I think this is a lot more Otto Lilienthal/Percy Pilcher than the Wright Brothers - who abhored leg-swinging/weight shifting as a means to control their gliders.
best
Paul
The US patent application is here: http://www.pat2pdf.org/patents/pat20090088911.pdf
If it has expired from the www.pat2pdf.org cache enter this patent number there: 20090088911
and it'll make you a PDF. What will they think of next?
I think this is a lot more Otto Lilienthal/Percy Pilcher than the Wright Brothers - who abhored leg-swinging/weight shifting as a means to control their gliders.
best
Paul
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Airfoilmod
Airfoilmod, Airbus do what you incredulously talk about on the A380. The outer tanks are filled half full on the ground to reduce wing downward bending. After takeoff one of the first transfers is to fill the outers full from the inners.
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There have been several posts with innovative ideas of what the phugoid is.
It might be useful to revisit the basics of the two pitch oscillatory modes .. both come from the mathematics involved in describing flight but can be understood adequately in a qualitative sense. The characteristics are aircraft design dependent and the motions will vary between Types.
Short Period Oscillation
The short period oscillation (known not very imaginatively as a SPO) is a bit like being on a boat in enclosed waters (ie a short fetch) where the wind waves are close together. If we were to look at the motion of the boat from the side we would see it going up and down comparatively quickly .. the period (time between successive crests) is reasonably short and the motion can be reasonably uncomfortable for the occupants.
For the aeroplane, the SPO is associated with a varying angle of attack and the two main concerns are
(a) the period, typically, is in the order of a second or so. As this is within the normal range of human response time, it is very easy for the pilot to excite the SPO (ie cause the magnitude of the oscillation to increase) by trying to control the initial motion (but getting into phase with it), leading to the phenomenon known as a pilot induced oscillation (PIO)
(b) associated with (a), loss of control or structural integrity are very real concerns
Design- and certification-wise, the SPO must be heavily damped for the aircraft to be acceptable.
Long Period Oscillation
The long period oscillation is a bit like being out in the ocean and looking at the effect of the ocean swell on our boat. From the side, the boat rises and falls with the swell over a comparatively long time.
The period, in this case, may be in the order of a minute or two. Generally, the period will be longer for larger aircraft, and shorter for the small machines.
The long period oscillation is characterised by an approximately constant angle of attack and is associated with a cyclical exchange of airspeed and altitude. If the aircraft is constrained to level flight, the motion will degrade into a cyclical speed oscillation.
Provided the long period oscillation is not divergent (ie the oscillatory motion doesn't get larger as cycles progress) the motion is only a bit of a nuisance for (and easily controlled by) the pilot.
Long period oscillation was the subject of research by Lanchester is the early 20th century and he coined the term "phugoid" for the motion (chaps of his era routinely were schooled in the classics and were much beloved of citing Greek and Latin roots in their naming of things ..)
Further reading
Any of the standard engineering undergrad Flight Mechanics texts will give a detailed mathematically modelled run down of both motions (although such knowledge is probably not overly necessary for the pilot) and I have no doubt that there are numerous useful descriptions on the Web.
It might be useful to revisit the basics of the two pitch oscillatory modes .. both come from the mathematics involved in describing flight but can be understood adequately in a qualitative sense. The characteristics are aircraft design dependent and the motions will vary between Types.
Short Period Oscillation
The short period oscillation (known not very imaginatively as a SPO) is a bit like being on a boat in enclosed waters (ie a short fetch) where the wind waves are close together. If we were to look at the motion of the boat from the side we would see it going up and down comparatively quickly .. the period (time between successive crests) is reasonably short and the motion can be reasonably uncomfortable for the occupants.
For the aeroplane, the SPO is associated with a varying angle of attack and the two main concerns are
(a) the period, typically, is in the order of a second or so. As this is within the normal range of human response time, it is very easy for the pilot to excite the SPO (ie cause the magnitude of the oscillation to increase) by trying to control the initial motion (but getting into phase with it), leading to the phenomenon known as a pilot induced oscillation (PIO)
(b) associated with (a), loss of control or structural integrity are very real concerns
Design- and certification-wise, the SPO must be heavily damped for the aircraft to be acceptable.
Long Period Oscillation
The long period oscillation is a bit like being out in the ocean and looking at the effect of the ocean swell on our boat. From the side, the boat rises and falls with the swell over a comparatively long time.
The period, in this case, may be in the order of a minute or two. Generally, the period will be longer for larger aircraft, and shorter for the small machines.
The long period oscillation is characterised by an approximately constant angle of attack and is associated with a cyclical exchange of airspeed and altitude. If the aircraft is constrained to level flight, the motion will degrade into a cyclical speed oscillation.
Provided the long period oscillation is not divergent (ie the oscillatory motion doesn't get larger as cycles progress) the motion is only a bit of a nuisance for (and easily controlled by) the pilot.
Long period oscillation was the subject of research by Lanchester is the early 20th century and he coined the term "phugoid" for the motion (chaps of his era routinely were schooled in the classics and were much beloved of citing Greek and Latin roots in their naming of things ..)
Further reading
Any of the standard engineering undergrad Flight Mechanics texts will give a detailed mathematically modelled run down of both motions (although such knowledge is probably not overly necessary for the pilot) and I have no doubt that there are numerous useful descriptions on the Web.
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I dont know about all the maths jargon but how about this.
Would you choose to burn off fuel thus reducing aeroplane controllability but decreasing the chances of a large fire or explosion on landing OR land quickly with large amounts of fuel to control roll but risking a fireball if you get the landing wrong??
Would you choose to burn off fuel thus reducing aeroplane controllability but decreasing the chances of a large fire or explosion on landing OR land quickly with large amounts of fuel to control roll but risking a fireball if you get the landing wrong??
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Cosmos2 wrote:
Patents are about protecting ideas and also the concepts and ideas surrounding those through specific embodiments of those ideas. Whether the example used is "sensible" or "practical" or not is to a degree irrelevant.
While a patent might be entitled "a system and method for the vertical lifting of airplanes" the key idea that it is covered will be found in the claims of the patent which also cover all the potential ways in which that idea might be implemented.
What Airbus did here was to make sure that the idea of controlling an aircraft via these means has been recorded as being Airbus' idea.
Now, whether given current technology this idea or the described implementation is practical or not is irrelevant. Firstly this patent might be part of a much larger family of patents - too big a idea can not be patented, or is very hard to anyway. Secondly in patent litigation the number of patents the the total amount of claims needs to be taken in to account - claims are often settled on the tit-for-tat basis.
Now a hypothetical example here might be that someone in Seattle might introduce a device onto the 787 that moves fuel around the aircraft to reduce stress on various components - a kg of fuel saved is still a kg of fuel. Now Airbus, might challenge that and state that such device is covered by one of the claims in this patent, eg: claims 1 to 4. Now if a court decides that the claims are broken by Boeing then they can either remove the device from their aircraft, pay Airbus a license fee or design a work-around (this is the basis of innovation!). Given the claims above such an innovation might be a mechanical linkage rather than one by computer (claims 2 and 3, and figure 1). Of course, maybe, Embraer have a patent for this and they sue Boeing.
Hopefully you get the idea...
Many many many companies have similar "strange" looking patents, even Boeing!
plugnik - thanks for posting the links, much appreciated,
fc101
E145 Driver
I'm not sure we can take all of the Airbus patents seriously. They also have this one for vertical lifting of airplanes...
While a patent might be entitled "a system and method for the vertical lifting of airplanes" the key idea that it is covered will be found in the claims of the patent which also cover all the potential ways in which that idea might be implemented.
What Airbus did here was to make sure that the idea of controlling an aircraft via these means has been recorded as being Airbus' idea.
Now, whether given current technology this idea or the described implementation is practical or not is irrelevant. Firstly this patent might be part of a much larger family of patents - too big a idea can not be patented, or is very hard to anyway. Secondly in patent litigation the number of patents the the total amount of claims needs to be taken in to account - claims are often settled on the tit-for-tat basis.
Now a hypothetical example here might be that someone in Seattle might introduce a device onto the 787 that moves fuel around the aircraft to reduce stress on various components - a kg of fuel saved is still a kg of fuel. Now Airbus, might challenge that and state that such device is covered by one of the claims in this patent, eg: claims 1 to 4. Now if a court decides that the claims are broken by Boeing then they can either remove the device from their aircraft, pay Airbus a license fee or design a work-around (this is the basis of innovation!). Given the claims above such an innovation might be a mechanical linkage rather than one by computer (claims 2 and 3, and figure 1). Of course, maybe, Embraer have a patent for this and they sue Boeing.
Hopefully you get the idea...
Many many many companies have similar "strange" looking patents, even Boeing!
plugnik - thanks for posting the links, much appreciated,
fc101
E145 Driver
Pedant head on again.
But earlier you said
Surely there would be no freefall. 
But earlier you said
At that point the jet would start its engines and begin moving forward, dragging the ferry along with it. Upon reaching stall speed, the jet would cut loose from the ferry.
