F-Yeah Aviation!

[fyeahaviation]

This at first seems to be a (relatively) unremarkable picture. However, this was taken during a program by Nasa Dryden to develop a system for aircraft control in the event of control surface failure. The concept is to use differential engine thrust to maneuver the aircraft, known appropriately as the Propulsion-Controlled Aircraft (PCA) system. This feat is made more impressive given the testbed. 

 The aircraft itself is the McDonnell Douglas MD-11, which has an interesting history itself. The design is a modified DC-10, note the center landing gear which was added to the design as part of range-increasing modifications implemented during later manufacturing blocks. The MD-11 is also reportedly difficult to land, as the CG was moved backward (making the aircraft less stable) and the tail area decreased as compared to the DC-10. This combination has perhaps contributed to the three incidents of flip-over during hard landings of MD-11 aircraft, a black mark not matched by any other type. 

[fyeahaviation]

This is the USAF Museum of the Air Force aircraft of the month, the Beech QU-22B. This is essentially a Beech Bonanza with the addition of tip tanks, and a large electric generator, which is visible as the large hump in the cowling. The aircraft can be flown both as a piloted aircraft and also unmanned. 

[fyeahaviation]

Augustine's 16th Law: In the year 2054, the entire defense budget will purchase just one aircraft. This aircraft will have to be shared by the Air Force and Navy 3-1/2 days each per week except for leap year, when it will be made available to the Marines for the extra day.

It is very important to notice that the plot shown is a semi-log plot. 

Photo Credit : Autopilot (Own work) via Wikipedia

[fyeahaviation]

Pictured here is the Douglas X-3 being towed to the lakebed at Edwards AFB for flight testing. The aircraft was designed for a number of research goals, including sustained flight at Mach 2, low aspect ratio wings (meaning the wingspan to chord length ratio was very low) and the use of titanium in aircraft construction. Due to way mass was concentrated in the fuselage, the X-3 was subject to large amounts of roll coupling, meaning that a roll input resulted in large movements around the pitch and yaw axes. The knowledge gained from the tests paved the way for high speed aircraft like the F-104 to be successfully designed and flown.

The aircraft can now be seen in the X-Plane hangar at Wright-Patterson AFB in Dayton, Ohio. 

[fyeahaviation]

The nature of an aircraft design is compromise. That is, the goal is to balance the different aspects of the total performance while trying to optimize a few (or one) based on well-defined mission requirements

Thomas Corke

[fyeahaviation]

During the space shuttle program, the idea came about that fitting a drag chute could reduce the loads and wear on the brakes of the shuttle. However, for obvious reasons, flight testing on the shuttle itself was not possible. The solution was to outfit NASA's B-52 mother ship with the chute and use that to validate the expected loading from the chute. The chute was finally deployed on Endeavour in 1992.

[fyeahaviation]

Aeronautics really might be called the "other NASA," distinct in its charge, methodologies, and scale. [...] The contrast with the space program is telling: where NASA has gone to considerable lengths to justify the space program and explain how space innovations feed into the country's more terrestrial needs, aeronautics research has had a direct and undeniable impact on commercial and military technology development. Its positive economic effects are generally accepted.

Robert G. Ferguson

[fyeahaviation]

"Bernoulli's Theorem doesn't help you the least in flying. While it is no doubt true, it usually merely serves to obscure to the pilot certain simpler, much more important, much more helpful facts."

Wolfgang Langeweische on the application of Bernoulli's Theorem to the cockpit.

[fyeahaviation]

One of the most interesting groups in aviation history must be the founders of the Jet Propulsion Laboratory. The group invented the concept of JATO, and was instrumental in the development of rocketry in the United States.  Headed by Theodore von Karman (center), a pioneering scientist in fluid dynamics (and a student of Ludwig Prandtl) the group also included figures such as Frank Malina (center-right), who would go on to be a famous artist in his own right. However, the oddest figure is likely Jack Parsons (not pictured) who, after his work in rockets, became involved with Aleister Crowley and L. Ron Hubbard.

[fyeahaviation]

Sean D. Tucker, flying the Oracle Challenger III, clips a ribbon (seen right) at Oshkosh 2013. 

[fyeahaviation]

In the early days of World War II, the US Army Air Corps felt that there would be a need for an interceptor type aircraft to provide defense from air attacks on the United States. As many "civilian" companies were being awarded military production contracts during the war, Fisher Body (the body panel manufacturer for General Motors) submitted a proposal known as the P-75 Eagle (pictured.) To facilitate a quick turnaround, the aircraft heavily leaned on developed components, such as the landing gear from the Vought F4U Corsair. As the war progressed, it became apparent that the real need in the Air Corps would be for a long range escort fighter. The design was adapted to fit the new role, but after a number of failures the project was eventually canceled in late 1944.

[fyeahaviation]

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.

[fyeahaviation]

"The principle is most important, not the detail."

Theodore von Kármán

[fyeahaviation]

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

[fyeahaviation]

"If nothing else you don't want to look stupid in the NTSB report"

-Rick Durden on reasons to err on the side of caution

[fyeahaviation]

Redacted

[burtuppercut]

“”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)

[helpdeanwinchester]

sorry what was that?

i can’t hear you

over the engines

of our beautiful

fucking

aircraft

[fyeahaviation]

This was just an old joke, but it's hard to argue with this refutation. :)

[fyeahaviation]

The Bernoulli "Fallacy"

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:

http://www.cracked.com/article_20669_6-ridiculous-science-myths-you-learned-in-kindergarten_p2.html

http://physicsfocus.org/colin-white-physics-myths/

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.