Would planes be better if they were more like birds?

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REVAN

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Why does everyone seem to think coordinated flight is the only type of flight that matters? There are times when you want or need un-coordinated flight, just like there are times you need to over- or under- steer a car, just like there are times you need your snow skiis to not be parallel, just like there are times you need your sailboat to be listing to one side, just like there are times you allow your phone bill to be a month past due because you really need the air conditioning not shut off in a hot summer, etc. etc. etc.

Even in a sailplane, where the overall goal is maintaining maximum efficiency, there are a hundred times when you need to throw something out of coordination for one reason or an other. Not just during landing either!
What's the advantage of having de-coordinated controls? What's the handicap?
 

Victor Bravo

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The advantage of de-coordinated controls is that the pilot can adapt to any unusual or non-textbook factors that happen.

For one rather extreme (but often used) example, flying close to mountains or steep terrain in gusty conditions. You want to have a small to moderate bank angle away from the terrain, even when flying "straight", because if a gust tries to push you toward the terrain you can get the aircraft away with one quick pull on the stick. By flying un-coordinated, you have pre-positioned the wings at an angle where their lift can be used instantly to prevent being slammed into the mountainside.

If you were flying "level", you would first have to roll the aircraft away from the mountain and then you can convert the wing's lift into escape. But on most aircraft, the roll response is far slower than the pitch response, i.e. the one or two seconds you waited for the aircraft to roll into a bank is one or two seconds too long to survive the gust.

Cross-controlled landings, slips, etc. are of course a far more common (and less extreme) use of un-coordinated flight.
 

jedi

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-the REAL methode (simple,energy efficient) of man powered flying device,
not ornithopter but weavy flying=
And not just a theory. The Tramopfoil and AquaSkipper demonstrate the theory if only in water rather than the air.

I have limited experience with this on the hydrofoil, as well as paragliders and hang gliders. Water is a better medium because of the greater density and human power is too limited for level flight in typical flying machines.

IMHO conventional bird like powered flapping is more promising in aircraft and that is where present development is needed. The problems (and solutions) are much more complex than commonly recognized as demonstrated by the relatively poor efficiency of the currently flying flapping wing devices, Festo robotic seagull included. That said, Festo's work is fantastic! I hope that you all will charge on.
 
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OrVNstabilize

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Real flapping wing propulsion is so mind-numbingly complex and difficult to emulate/replicate that even if breakthroughs and technologies in artificial muscles, tissues, joints, feathers, etc. were available, it still wouldn't be solved. IMO it has to start with the understanding of the fundamental principles and mechanisms of how birds generate lift and thrust. Many attempts at replicating the flapping motion by simplifying it into the familiar oscillating up and down motion or some type of figure 8 motion with wing articulation aren't helping to make progress and actually hurting it because people see how crude, clumsy and inefficient it is compared to propellers and just dismiss the idea of flapping propulsion altogether.
 

Aesquire

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But since I did not originally come from the hang glider world, I have zero flying experience in the prone position like Revan's renderings. It might be tiring, it might be uncomfortable, it might be... wait for it... a pain in the neck.
True. It can be. I've got prone and supine harnesses, and while I learned prone, I switched to supine for the bulk of my flying. I never really had the need to look straight down, and if I want to , I just lean to one side. The new sitting/supine harnesses developed for paragliding are quite comfortable.
 

jedi

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Real flapping wing propulsion is so mind-numbingly complex and difficult to emulate/replicate that even if breakthroughs and technologies in artificial muscles, tissues, joints, feathers, etc. were available, it still wouldn't be solved. IMO it has to start with the understanding of the fundamental principles and mechanisms of how birds generate lift and thrust. Many attempts at replicating the flapping motion by simplifying it into the familiar oscillating up and down motion or some type of figure 8 motion with wing articulation aren't helping to make progress and actually hurting it because people see how crude, clumsy and inefficient it is compared to propellers and just dismiss the idea of flapping propulsion altogether.
Yes but, like many ideas, concepts or products, once you truly understand them, the concept is not as complicated as you once thought it was.

If you have never rowed a boat getting those darn oars to work right is downright frustrating. Once you have the proper equipment and have developed the skill you can row all day without thinking about it. Understanding and explaining the operation of a sculling ore (Sculling - Wikipedia) can be made as complex or as simple as you like but in the end, with the proper equipment and instruction, it can be done without a detailed understanding of the entire process and is a very efficient method of marine propulsion.
 
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henryk

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once you truly understand them,
=for flapping wing propulsion we need know UNSTEADY (much complicated) aerodynamic,
with NONLINEAR "coefficients"...

-on the base of STATIONAR or quasi unsteady aerodynamic we got small effects
(see FESTO works...)

BTW=simple dr Wolfs methode of man powered oscillating wing propulsion=horisontal fly on hang glider (ZETA 77)
 
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jedi

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I actually can't say, because both have equal appeal to me, albeit on opposite sides of the spectrum. The concept of a little jet powered pocket rocket that lets you zoom around like a character in the Marvel Comics movies... that's !(#&*$& cool. But since I did not originally come from the hang glider world, I have zero flying experience in the prone position like Revan's renderings. It might be tiring, it might be uncomfortable, it might be... wait for it... a pain in the neck.

The seagull thingie would definitely interest me as a soaring pilot, and as you well know there were plenty of gull-winged gliders. But if a soaring seagull contraption gave me the same aching painful sore neck from the prone position... maybe I'd get tired of that too?

What I would inject into the conversation is to remind everyone that birds were designed with their neck and head attached that way because almost all birds' primary activity while flying is looking down to find their lunch (with greatest respects to Jonathan L. Seagull, whose primary reason for flying was enjoyment and aerobatics). My reason for flying around like a bird (whether in the jet owl or the soaring gull) would not be trying to find field mice or fish down below me.

So comfort and orthopaedic alignment might be higher on the list for this spoiled, well-fed human :)

The "mission profile" and recreational goal of the "Jet-Owl" category of flying machine would be very well met by a jet powered derivative of the (original, monowheel retractable) Janowski J-5 Marco. Great visibility, great maneuverability, but sailplane-level comfort. The "Seagull" experience, ridge soaring on the beach cliffs and such, could be done with a cleaner version of an open cockpit glider, maybe redesigned for better visibility, but still a supine seat. Maybe an open cockpit derivative of the Monnett Monerai with its seat sling, but perhaps without the upper canopy.

The seagull experience just wouldn't be complete without a small opening in the bottom of the seat sling, so I could !*#& on the cars in the beach parking lot.
Good answer VB, and thanks for taking the time to respond.

Sore neck muscles from supporting the head and helmet during a long flight are a common complaint among hang glider pilots. Like in any seated position good ergonomics is an important part of the design. I have seen a wartime report from the WW II military flying wing days on prone seating development and comfort. It concluded that with proper design some pilots found the prone position to be as comfortable or more comfortable than the seated position particularly for long duration flights. Unfortunately, I have not been able to find that report recently for reference or review.

IMHO - Most hang gliders harnesses lay the pilot too flat in order to present the least frontal area to minimize drag caused by the poor aerodynamics of the harness. The most comfortable prone position approimates the body profile of the supine seating position with the pilot rotated about 120 degrees head up and forward so as to be nominally looking about 50 degrees forward of the vertical. This can have a better visual range than the extreme supine position where the pilot is nominally looking about 40 degrees forward of the vertical up position with the instrument pannel and pilot's body blocking much of the forward view and the head rotated chin towards the chest. In the semi-prone position the hips, thigh and knees support much of the pilot's weight and the feet are able to press against a foot rest.
 

REVAN

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The advantage of de-coordinated controls is that the pilot can adapt to any unusual or non-textbook factors that happen.

For one rather extreme (but often used) example, flying close to mountains or steep terrain in gusty conditions. You want to have a small to moderate bank angle away from the terrain, even when flying "straight", because if a gust tries to push you toward the terrain you can get the aircraft away with one quick pull on the stick. By flying un-coordinated, you have pre-positioned the wings at an angle where their lift can be used instantly to prevent being slammed into the mountainside.

If you were flying "level", you would first have to roll the aircraft away from the mountain and then you can convert the wing's lift into escape. But on most aircraft, the roll response is far slower than the pitch response, i.e. the one or two seconds you waited for the aircraft to roll into a bank is one or two seconds too long to survive the gust.

Cross-controlled landings, slips, etc. are of course a far more common (and less extreme) use of un-coordinated flight.
The question was, "What is the advantage to having de-coordinated controls?", not what is the advantage to executing de-coordinated flight under certain conditions. What are the pros and cons to an aircraft with a wing that exhibits adverse-yaw to one with pro-verse yaw? Keep in mind that the pilot can still purposefully de-coordinate roll and yaw if they choose to do so.

As far as I can tell, a wing that exhibits adverse-yaw only brings problems that need to be solved by the pilot in real time. An advantage is that you can make a plane that looks traditional. To me that is not an advantage, but others may want a look that is familiar. Another advantage/disadvantage is that it will spin "quicker". IMO: that is a disadvantage unless you are doing aerobatics and need to snap it.
 
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speedracer

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Good answer VB, and thanks for taking the time to respond.

Sore neck muscles from supporting the head and helmet during a long flight are a common complaint among hang glider pilots. Like in any seated position good ergonomics is an important part of the design. I have seen a wartime report from the WW II military flying wing days on prone seating development and comfort. It concluded that with proper design some pilots found the prone position to be as comfortable or more comfortable than the seated position particularly for long duration flights. Unfortunately, I have not been able to find that report recently for reference or review.

IMHO - Most hang gliders harnesses lay the pilot too flat in order to present the least frontal area to minimize drag caused by the poor aerodynamics of the harness. The most comfortable prone position approimates the body profile of the supine seating position with the pilot rotated about 120 degrees head up and forward so as to be nominally looking about 50 degrees forward of the vertical. This can have a better visual range than the extreme supine position where the pilot is nominally looking about 40 degrees forward of the vertical up position with the instrument pannel and pilot's body blocking much of the forward view and the head rotated chin towards the chest. In the semi-prone position the hips, thigh and knees support much of the pilot's weight and the feet are able to press against a foot rest.
I flew hang gliders for many years in the prone position and was never uncomfortable during flights of up to 3 hours. During the current distance world record of 474.7 miles the pilot was prone for over 10 hours IIRC. Then there was the Honolulu jeweler who set the duration record at Makapuu, Oahu (my favorite flying site) of 48 hours flying prone.
 

REVAN

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I have seen a wartime report from the WW II military flying wing days on prone seating development and comfort. It concluded that with proper design some pilots found the prone position to be as comfortable or more comfortable than the seated position particularly for long duration flights.
A head support could be developed for long flights. A massage table comes to mind, which is known for being very comfortable. Keep in mind that a regular chair without a head rest, especially one that is reclined, is not comfortable for long durations either.
 

jedi

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True. It can be. I've got prone and supine harnesses, and while I learned prone, I switched to supine for the bulk of my flying. I never really had the need to look straight down, and if I want to , I just lean to one side. The new sitting/supine harnesses developed for paragliding are quite comfortable.
Yes! Paraglider pilots need to keep a good eye on the wing to make sure it is still there and inflated. I would not want to fly a paraglider prone much as I would like to fly Super Man style while hanging from a sky hook.
 

wsimpso1

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People have been mimicking birds for airplanes since the 1920's. It has never made a more efficient airplane.

On top of that, most feathered wings, while really adaptable to a huge speed range, do not lend themselves to high enough speeds. The fastest birds get their speed in a dive with wings folded or pulled way in, and they only get to about the Vne of my Archer. Now imagine trying to get to the Vne of Cirrus with fake feathers trying to flutter in the breeze.

I strongly suspect that feathered wings are much more appropriate at Mach numbers around 0.1 than they are at 0.3-0.6. Have fun guys.

Billski
 

jedi

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People have been mimicking birds for airplanes since the 1920's. It has never made a more efficient airplane.

On top of that, most feathered wings, while really adaptable to a huge speed range, do not lend themselves to high enough speeds. The fastest birds get their speed in a dive with wings folded or pulled way in, and they only get to about the Vne of my Archer. Now imagine trying to get to the Vne of Cirrus with fake feathers trying to flutter in the breeze.

I strongly suspect that feathered wings are much more appropriate at Mach numbers around 0.1 than they are at 0.3-0.6. Have fun guys.

Billski
I am not sure I believe it but a recent PBS program on bats reporting measuring a flight speed of 100 mph (160 kph).

In general, the larger the aircraft the higher the speed due to the square/cube effect.

Apply the scale speed adjustment to a mallard duck and it would do ok at the Reno races.

I do not think an ornithopter will ever compete with a jet transport for high speed but I don't think a jet transport will ever land in a tree either. (Airbus flown in France is the exception to the rule!)
 

DennisK

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No successful “landing gear” has been found. The “Festo Bird” and other projects are hand launched and “belly” land. The need for additional landing gear development was pointed out in prior post page 2 post # 21.
Aside from foot launching (which is my interest), "wheels on long legs" seems like the obvious solution. Perhaps with a multi-jointed leg design to fold up more compactly. Running/jumping legs would certainly be cool, but high torque actuators are heavy. And the feet of a goose essentially trace out the shape of a rolling wheel as they run and flap to build up speed, so an actual wheel would likely work just as well. The jump-flap vertical takeoff of small birds will probably not be possible for any manned ornithopter due to actuator weight (both leg and wing actuators). But hopefully we can get STOL performance, along with the high efficiency, low noise, greater control in gusty/turbulent air, folding up into convenient size when landed, and plain old beauty of feathered wings.

The folding mechanism design has not been addressed. In my opinion this is the most important parameter to develop for the large man carrying version. It is even more significant for an estimated 32 foot span sea gull than the proposed 26 foot span owl. In my opinion it is also the problem that is most easily solved as the bio-folding is easily studied and understood. Three D modeling is available and straight forward. Furthermore, wing folding for storage and transport is one of the most requested optional design parameters of the EAB design process.
If it were easy, someone would have done it by now :) But I do agree with your other posts that it won't seem so difficult in hindsight. In the process of writing about my difficulties with the feathers around the wrist joint, I think I realized something dumb I've been doing (rubber duck debugging really works :) ). Time to rework the 3D model again and print out some new bones.

On top of that, most feathered wings, while really adaptable to a huge speed range, do not lend themselves to high enough speeds. The fastest birds get their speed in a dive with wings folded or pulled way in, and they only get to about the Vne of my Archer. Now imagine trying to get to the Vne of Cirrus with fake feathers trying to flutter in the breeze.
Yep, I do expect flutter to be a major problem with fake feathered wings. Real feathers have near-magical vibration damping properties that I don't think will be possible to mimic.
 

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OrVNstabilize

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Yes but, like many ideas, concepts or products, once you truly understand them, the concept is not as complicated as you once thought it was.

If you have never rowed a boat getting those darn oars to work right is downright frustrating. Once you have the proper equipment and have developed the skill you can row all day without thinking about it. Understanding and explaining the operation of a sculling ore (Sculling - Wikipedia) can be made as complex or as simple as you like but in the end, with the proper equipment and instruction, it can be done without a detailed understanding of the entire process and is a very efficient method of marine propulsion.
Yep that's essentially what I was trying to get at, it's only less complex once you figured it out. Just wanted to hi-light the importance of actually understanding the fundamental principles of flapping wings because far too many have built or tried to build one(the many failed ornithopters and ones like this for example) without first having the knowledge of how birds actually generate lift/thrust. So you end up with these oversimplified mechanisms and contraptions that just looks ridiculous and would never work.
 
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