An idea that keeps popping up over the years is the idea of a cyclocopter or cyclogyro. The basic principle is to rotate a set of wings (or rotor blades) in a cylindrical motion. By varying the angle of attack as the airfoils travel around the circle, one can vector thrust in any direction normal to the rotational axis. The mechanics of such a system are more complex than that of a traditional helicopter. However, the forward flight speed would not be subject to the same limitations as that of a helicopter. In addition a properly working model would theoretically be more maneuverable than a helicopter, as the thrust could be vectored horizontally as well as vertically, rather than simply tilting the blade disc.
Prototypes are being built at the University of Maryland and at the Seoul National University, as seen in the youtube links.
The idea, however, is not new having been patented in 1927.
Seen in this photo is the Douglas YC-15. The aircraft was designed to take off in less that 1000 feet while carrying a full load. The really cool thing about this aircraft is that engine exhaust is diverted through the wing and diverted downward over the flaps. This blown flap design allows the the flow to remain attached at very high angles of attack, allowing the wing to produce somewhere between three and five times the maximum lift possible compared to a “standard” wing. The idea behind it was understood for some time before the aircraft was built, but was not that feasible until high-bypass engines were common due to the high temperature of gas produced by lower bypass engines.
Photo Credit: Akradecki via Wikipedia
This was just an old joke, but it’s hard to argue with this refutation. :)
“”If it’s ugly, it’s British; if it’s weird, it’s French; and if it’s ugly and weird, it’s Russian.””
— Anonymous (via fyeahaviation)
sorry what was that?
i can’t hear you
over the engines
of our beautiful
Recently, I have seen a number of PopSci type articles on the generation of lift that claim that Bernoulli’s Theorem is incorrect. For example:
The statement that is called into question is : because the fluid elements travel farther along the top surface of the wing, and must meet with the corresponding fluid element that traveled along the bottom of the airfoil, the fluid along the top travels faster and thus exerts less pressure. This pressure difference is what causes the airfoil to produce lift.
Taken as a whole this statement is incorrect. There is no reason that simply because the fluid elements along the top of the airfoil have traveled farther they must travel more quickly. This is the part of the statement that is incorrect.
However, Bernoulli’s principle which simply states that as fluid particles travel faster, they exert less pressure is correct. Furthermore, the pressure differential caused by the differing speeds does correspond to the amount of lift produced by the airfoil. It is also worth noting that Bernoulli’s Equation as commonly written: [ p + 1/2 rho V^2 = constant ] is valid only for an incompressible, inviscid fluid. It can be proven from basic axiomatic principles of fluid dynamics and has certainly not been refuted since the 60’s as the second link could be interpreted to imply.
Really great blog, love all the quotes. I wanna reblog them all!
Thank you for your kind words.
I set this blog up just as an outlet for some of the better aviation stories and factoids that I have come across.
I am finishing up my PhD in Aerospace Engineering and have logged about 15 hours so far towards my PPL. Unfortunately both the financing and time commitments of these two activities are constantly at odds with one another. This explanation also goes a long way towards explaining the sporadic nature of the posts.
Linear analysis of supersonic wings predicts that increased camber and thickness will provide no benefit in terms of lift, but will only increase drag. While this is not the exact solution, it does provide an insight into supersonic wing design. Namely, that the best performing wings at supersonic speeds tend to basically be flat plates. This phenomenon was known early in the development of high speed aircraft, as evidenced on this photo of the X-1E.
The X-1E was essentially a modified version of the more famous X-1. Changes made include a conventional canopy and an even thinner wing, reaching only 4% thickness.
The exhaust plume of this NASA SR-71 is a beautiful example of shock diamonds (sometimes called Mach disks). This flow phenomena is caused by a mismatch of exhaust pressure to the ambient air. The stream then undergoes a series of alternating Prandtl-Meyer expansions and oblique shocks, causing portions of the flow to be hotter then colder. The hotter sections give off a distinctive glow, leading to the visualization of the shock diamonds.
This famous photograph shoes condensation of the ambient air due to an oblique shock caused by the passing of an F-22 raptor.
Very well put together video, with a number of really interesting clips of the effects of supersonic flow. Also contains commentary.
Radar was invented circa 1940, and like all technological advancements of that period, made leaps and bounds in terms of improvements during the Second World War. Shown in this NOAA photograph is the nose mounted radar unit of the Northrop P-61 Black Widow (an interesting aircraft in its own right). The radar in this aircraft was intended to allow the aircraft to seek out and shoot down enemy aircraft during night time engagements.
"He looked at an airplane in flight and realized it captured the inherent right of every man and woman to fulfill their great hopes and dreams."
- From the EAA biography of Paul Poberezny
Created by the Sonex company, seen here is the JSX-1 SubSonex aircraft. Powered by the PBS TJ-100 turbojet engine mounted just forward of the tail, this aircraft does a lot to address the question of putting affordability back into general aviation. It may not yet be the perfect answer, but something like the SubSonex is currently the most affordable (only affordable ?) way to introduce turbine power to the average pilot.
From the Sonex website: ” The SubSonex extends the Sonex Aircraft ‘Reality Check’ philosophy to become the first truly practical and affordable personal jet for recreational flying.”