Talk:Ornithopter/Archive 2

Archive 1

Archive 2

In popular culture

A section consisting entirely of entries such as

• In the book Freak the Mighty, Freak owns a ornithopter.

contributes nothing to the article, and ought to be removed. Feezo (send a signal | watch the sky) 04:57, 30 November 2011 (UTC)

Agree with the principle. Many f&sf novels use ornithopters as background elements--need not be listed here. Haven't read Dune recently so don't know how prominent ornithopters are. However, they are a significant plot element in H G Wells' The War in the Air, so I will add it. Maybe the criterion shouid be 'if ornithopters were removed,would the plot suffer?' NB--articles must be notable, content is not so restricted. D Anthony Patriarche (talk) 18:12, 2 March 2019 (UTC)

Contradiction in the article

This paragraph,

In propeller- or jet-driven aircraft, the propeller creates a relatively narrow stream of relatively fast moving air. The energy carried by the air is lost. The same amount of force can be produced by accelerating a larger mass of air to a smaller velocity, for example by using a larger propeller or adding a bypass fan to a jet engine. Use of flapping wings offers even larger displaced air mass, moved at lower velocity, thus improving efficiency.

implies that ornithopters can theoretically be more efficient than fixed-wing aircraft. But a few paragraphs later, the article flatly states that "Flapping wings increase drag and are not as efficient as propeller-powered aircraft."

Hopefully a qualified aerodynamicist can resolve this contradiction. 174.24.92.212 (talk) 14:10, 16 December 2011 (UTC)

Dubious physics - paragraph removed

I removed the following paragraph:

In propeller- or jet-driven aircraft, the propeller creates a relatively narrow stream of relatively fast moving air. The energy carried by the air is lost. The same amount of force can be produced by accelerating a larger mass of air to a smaller velocity, for example by using a larger propeller or adding a bypass fan to a jet engine. Use of flapping wings offers even larger displaced air mass, moved at lower velocity, thus improving efficiency.

I think this explanation fundamentally misunderstands Newton's Third Law. The energy of propeller thrust which is "lost" to friction in the air is absolutely necessary, and is always equal to the thrust produced whether at high or low speed. This paragraph does not say why low-speed air displacement is more efficient than high-speed, and also doesn't address the obvious potential for lower efficiency due to the need for the wing to flap upward while it is not producing thrust. Given that it has been unreferenced for over two years, I think it was time for it to go, unless someone can provide a reliable source to support this. -- Beland (talk) 04:43, 13 September 2013 (UTC)

The physics in the section removed is accurate, although poorly worded. The phrase "energy carried by the air" is ambiguous; it does not refer to momentum (vis a vis Newton3) but rather to the entropy generated in acceleration of the air mass. A small air mass accelerated to high velocity loses a greater share of energy to turbulence, heat, sound, etc, as compared to a large mass accelerated a small amount (but having equal momentum to the former case). I'll see if I can find a source specific to ornithopter physics.--Yeti Hunter (talk) 12:02, 20 February 2016 (UTC)

Lift vs Thrust

"if a static wing is kept at the same angle while moving up and down, it will produce no net lift or thrust."

I disagree. A curved wing displaces a different amount of air, depending on which way it's moving. E.G., a wing that is convex on top and concave on the bottom would generate lift if it were flapping straight up and down. In the same way, it could generate thrust if it were flapping at a fixed angle to the vertical.

"More recent vehicles [...] required the force of another towing vehicle in order to take off, and may not have been capable of generating sufficient thrust for sustained flight."

I'd classify something as "flying" if it's generating enough lift to stay airborne, whether or not it's also generating thrust. So I think the sentence should read "generating enough lift for sustained flight." Steve.Murgaski (talk) 22:00, 29 September 2013 (UTC)

Correct, and fixed. And for an example of a fixed-wing ornithopter, see any insect flight. But your example of using a simple airfoil is also a good illustration of how that can work. SamuelRiv (talk) 02:56, 2 October 2013 (UTC)

Getting Facts Straight in Wing Design Section

I would like to make some changes in the "wing design" section. First off, I don't know why there is a bunch of historical information in a section called "wing design". More importantly, some of the information is known to be false.

1. The first point I would like to revise is that Alphonse Penaud introduced the idea of a powered ornithopter in 1874. We know that Penaud flew a rubber-powered ornithopter in 1874, and this was "powered" in the sense that it was not using the muscles of the operator. However, Penaud was not the FIRST to achieve this. According to Octave Chanute's Progress in Flying Machines, Jobert already flew a similar rubber-powered ornithopter in 1871. Also, Gustav Trouve built a powered ornithopter in 1870, which was not rubber-powered. Therefore I would like to delete the claim that Penaud introduced the idea of a powered ornithopter. It could be expained better as follows: "The idea of a powered ornithopter (not using the muscles of the operator) was introduced c. 1870, with the work of Gustave Trouve, Jobert, and others. [2]" I don't think the statement about toys for children is important. It can be deleted. However, if someone wants to preserve this, it should be said "Some of these models were powered by rubber band, and found use as toys for children since the rubber band power source could not effectively scale up to the size of a manned aircraft."

2. Similarly, it is claimed that DeLaurier in 1991 made the first flight of a remotely piloted ornithopter. We know that Spencer flew a remotely-piloted ornithopter in 1961. We have videos and other references documenting this fact. So I want to delete the false statement, or replace it with a correct statement. — Preceding unsigned comment added by Nathanchronister (talk • contribs) 16:01, 15 February 2014 (UTC)

Phoenix

Can the Agile Flight Project Phoenix be mentioned in article ? See http://groups.csail.mit.edu/locomotion/flight.html

KVDP (talk) 09:39, 22 May 2014 (UTC)

Aircraft with propellers mounted in tiltable wings

In the Sci-Fi channel production of Dune, Frank Herbert's original ornithopter transportation was replaced with aircraft that had directionally tiltable wings in which were fixed propellers, used for VTOL, then for forward thrust as the short wings were tilted a bit. This same design appeared in the recent Showcase TV adaptation of Childhood's End. Do we have an article on this? I don't even know if such a vehicle is viable, but since the Dune show referred to them as ornithopters, it seems likely that some readers will come to this article looking for information on them, fictional or not.  — SMcCandlish ☺ ☏ ¢ ≽^ʌⱷ҅_ᴥⱷ^ʌ≼  07:20, 20 February 2016 (UTC)

The wings flapped? Or just changed their angle of attack for forward flight mode? If the former, it could be included as an example of ornithopters in fiction (could also include Kim Stanley Robinson's Mars trilogy). This article used to have such a section (2011 diff); not sure when or why it was removed - perhaps by User:Feezo who voiced his disapproval above? I don't mind such sections, as long as they are kept to a reasonable length and only include "notable" examples - while this is somewhat subjective and debatable, I think it's preferable to outright exclusion. --Yeti Hunter (talk) 12:22, 20 February 2016 (UTC)

Yes, I removed the section—I'm not against "in fiction/culture" sections in general, but I don't feel that the "X appeared in Y" list format contributes substantively to articles. I think the cut-off point where fiction/culture sections become "encyclopedic" is when we can cite secondary sources discussing, in this case, the use of ornithopters in such works. Feezo (send a signal | watch the sky) 18:04, 21 February 2016 (UTC)

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Plagiarism?

Bat wings are fundamentally different from bird wings, and it’s not just because birds have feathers and bats don’t. Generally, when roboticists design bird-inspired or insect-inspired robots, they use rigid approximations of the wings, or perhaps a few different rigid parts flexibly interconnected. Bat wings don’t work like this at all: The underlying structure of a bat’s wing is made up of “a metamorphic musculoskeletal system that has more than 40 degrees of freedom” and includes bones that actively deform during every wing beat. The wing surface itself is an “anisotropic wing membrane skin with adjustable stiffness.” This level of complexity is what gives bats their unrivaled level of agility, according to the researchers, but it also makes bats wicked hard to turn into robots. The dominant degrees of freedom (DOFs) in the bat flight mechanism are identified and incorporated in B2’s design by means of a series of mechanical constraints. These biologically meaningful DOFs include asynchronous and mediolateral movements of the armwings and dorsoventral movements of the legs. Also, he continuous surface and elastic properties of bat skin under wing morphing are realized by an ultrathin (56 micrometers) membranous skin that covers the skeleton of the morphing wings. We have successfully achieved autonomous flight of B2 using a series of virtual constraints to control the articulated, morphing wings .

Copies directly from this site. Granted, it has a citation, but wicked hard isn't an encyclopediac tone. I don't know if I should change this, reword this, delete it? Assistance required for a newbie, please.

References

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Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 13:07, 19 April 2022 (UTC)