# Tag Info

62

It depends. As always. If thrust is high enough, why not? Knife edge flight is a regular part of aerobatic performances, and the fuselage is producing almost* all the needed lift. This requires Enough speed, A low ratio of aircraft mass to fuselage side area, and Enough rudder deflection to trim the aircraft in a sufficiently high sidelip angle. For ...

61

There are a lot of good reasons not to roll such an airplane. If the plane has gyroscopic instruments, you might tumble them (cause the spinning gyro to hit the inside of the instrument). This can be expensive. You might easily over-stress the air frame. Normal category light aircraft are rated to -1.5 to +3.8Gs. (That's for a new aircraft) A botched ...

48

They're called aerobatic sights. Most attitude indicators (AI) that tell the plane's attitude with reference to the horizon don't have the full range of motion that aerobatic planes go through. If left alone, the AI would tumble out of control and become useless. That's why aerobatic pilots cage the AI—lock it in position before flying extreme maneuvers. ...

47

They are external attitude references. They're aligned with the aircraft's axes and positioned along the pilot's line of sight to give a quick visual guide to the aircraft's attitude during aerobatic maneuvres. You can see the alignment more clearly on this photograph

40

You can get negative load factors (g forces) in different ways than just flying upside down: Change in pitch: When you push on the control column, the pitch will start to decrease. Depending on how fast you do this, the load factor can even become negative from this. Some aircraft do this intentionally to reduce the g force to exactly zero: (image source: ...

38

It's a safety rule to protect the limits of the airframe and the pilot. See the video (also on youtube) from this Red Bull Air Race page which explains the rules. The G-limit is discussed from 3:30. The following is a quote from the relevant section of the video. Maximum load factor, that is how much G's is the pilot pulling. That has issues [...] the ...

34

The difference between an aileron roll and a barrel roll is that an aileron roll's centre of rotation is very close to or on the aircraft. A barrel roll has its centre of rotation around a point further away from the aircraft itself. The difference can be appreciated in this image: Image Source You can find out about the difference in feeling that these ...

34

There is no real helicopter capable of sustained inverted flight and certainly not of hovering inverted. The simple reason is that there is no operational need to do so. Is it theoretically possible? Yes, but you have a lot of engineering problems to overcome. In addition to inverted fuel and oil systems, the rotor head will be much more complex than ...

33

As you mentioned, drag is one of the reasons why retractable landing gears are used in the first place. But in order to use it, there are way more considerations than just drag. Scale: Size of the aircraft plays a big role here. Big aircraft have more room to keep the retracted landing gear. This is an issue as planes get smaller. Weight: Retractable ...

29

Yes, it has been done before in an even larger aircraft, the Boeing 367-80, very famously by "Tex" Johnston on August 7, 1955. This aircraft was the prototype for the Model 707. When a barrel roll maneuver is properly performed the aircraft remains in a positive-G state, so no "inverted flight" is experienced by the aircraft. According to the International ...

27

It doesn't only use biplanes, searching "wingwalking monoplane" provides these examples, of some low wing monoplane and high wing monoplane. Whatever the aircraft, it has to be able to fly slowly. (source) (not 100% about this one but it looks like one Klemm aircraft) (source) (Here one quite rare danish SAI KZ III equipped with a hatch behind the wing, ...

24

Design The key point is that these vehicles are not designed to perform such maneuvers. A coast-guard lifeboat is designed to self-recover from a capsize and can roll through 360 degrees without significant structural damage. A cruise-liner would not survive being rolled over completely. If a vehicle is not designed to perform a high stress maneuver it ...

24

Evolution has created this wonderful thing called stress. We tend to think of stress as something negative that is to be avoided, and that is certainly true: prolonged periods of stress will do all sorts of damage to your body and mind. However, for short periods of time, stress is a wonderful invention that lets us survive situations we otherwise wouldn't: ...

24

You are absolutely right, a load factor of greater than 1 is impossible to avoid in a proper barrel roll. The barrel part of its name comes from the spiral path the aircraft needs to perform in order to add a centrifugal acceleration which is greater than gravitational acceleration at the top of the roll. This is the condition to ensure a still positive ...

23

Markus Voelter interviewed Matt Hall for an episode of his omega tau podcast. They discuss this incident in more detail at 1:13:00. The aircraft experienced a high speed g stall, also called an accelerated stall. Stall is determined by the angle of attack, which is the angle of the airflow hitting the wing. Stall is most often thought of at low speed, ...

22

Acrobatic is being incorrectly used, although it is slightly more complicated than that. "Aerobatic" refers specifically to flight, and "acrobatic" refers specifically to feats of the human body, so referring to an aircraft as performing acrobatics is wrong. That said, the word "aerobatic" is derived from "aero-acrobatics" and sounds nearly identical, so ...

22

In a barrel roll, the aircraft rotates both in its longitudinal and lateral axes, while in case of aileron roll, the rotation is only about the longitudinal axis. A barrel roll, image from flightsimbooks.com If properly executed, there is no change in alttitude in case of an aileron roll, while during barrel roll, the aircraft follows a helical path. An ...

21

That is an enclosure for a counterweight, either made from steel or lead to balance the aileron and/or reduce control flutter in various flight regimes. The extension provides an additional lever arm to alter the moment of inertia about the aileron’s axis of rotation. These are usually added or refined during flight testing to remove undesirable flutter or ...

20

No. This would require a docile pitch behavior of the airframe up to approx. 110° angle of attack. The design of both the Su-27 and the MiG-29 is based on a geometry that has been carefully optimized by TsAGI to behave nicely over its full AoA range, a care that has not been spent by General Dynamics while designing the F-16. The specifications did not call ...

19

Aerobatic pilots typically use "aerobatic practice areas" when they practice. Many of the Part 91 rules which would need to be broken in order to practice aerobatics are waived within these aerobatic practice areas (such as the 1,500 ft. "floor" for normal aerobatics in 91.303(e)). The FAA has to approve them, and their guidance includes a good description:...

19

A long time ago aerobatic aircraft had just a single tank with a flop tube inside it. This works "OK", but when you're doing something complicated with a half-empty or mostly-empty tank, it's too easy for the flop tube to ingest air instead of fuel. This leads to performance problems with both the engine and the pilot. The solution is to have a very small ...

19

3 reasons: The really obvious one; biplanes had the interplane structural network to hang on to when doing the wing walking. It's a heck of a lot safer for the wing walker. Even today, most of the wing walker acts use Stearman or Waco biplanes. They generally have lower wing loadings than comparable monoplanes so could fly slower. They were readily ...

17

The tailwheel is much lighter and smaller than a nose wheel. That means reducing airplane overall weight and drag (because the landing gear is usually fixed). And it's probably cheaper, too.

17

I'm not sure if you're asking about flying such an aircraft (e.g. renting one) or owning one. But either way the answer is yes. I've flown a Hawker Hunter at a (now-defunct) location in Cape Town on a mixed low-level/acrobatic flight along the coast. There were no restrictions on who could fly in the aircraft apart from the obvious ones (no kids; must have ...

17

Essentially a flyby over the runway is nothing more than a planned and prepared go-around from a low altitude. If you say it is a stunt then it probably is not allowed under most legislations. And because of noise regulations airports aren't too happy with the manoeuvre either. However, nobody will stop you from going around if you "forget" to put ...

17

This is a case of divergent design, and you can't know the answer without asking why current aircraft are designed they way they are. Following the work of Col. John Boyd in the 1960's in developing the 'Energy-Maneuverability Theory', the U.S. and allies primarily designed combat aircraft and tactics around the idea that an aircraft's specific energy state ...

17

A typical GA airplane will draw fuel from at or near the bottom of the tank. An aerobatic airplane will have a hose from the engine to the middle of the tank, then on the inside of the tank there will be another flexible hose with a weight on the end. This inside hose is called a "flop tube". When the plane is in upright flight, the "clunk weight" on the ...

17

An aerobatic aircraft (as well as any aircraft) can sustain 0g until the pilot pulls up, the aircraft hits the ground, or reaches terminal velocity. In order to sustain 0g the aircraft must be accelerating towards earth at $9.8 m/s^2$ (meters per second squared). That means there isn't much time before the aircraft reaches its maximum speed. Once the ...

16

The aircraft in the video is a remote-controlled (rc) airplane. Why it can "hover" is simply: The thrust generated by a big fan / rc-jet-engine is much higher than the weight of the plane. If the force generated by the turbine is the same as the downward-force of weight of the airplane, it hovers. By very carefully adjusting the thrust and placing ...

16

Strictly speaking, a 'pure' aerobatic aircraft doesn't need a retractable landing gear. For such an aircraft maneuverability is much more important than speed. In fact, the aircraft can't fly too fast or the spectators are going to miss the show. In case of air races, the weight penalty of having a retractable landing gear is huge- in addition to the ...

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