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 ...


26

Pulseworks makes some full motion sims that are capable of inverted flight and infinite barrel rolls. These sims fall into the entertainment category more than the training category, but they are full motion, in cockpit sims. I have also been in a similar type of sim at a Harris/Boeing sponsored party in Seattle made by a company whose name I cannot ...


19

In the movie Flight (2012), Captain Whittaker (Denzel Washington) does not explain why he deliberately inverted his aircraft, but the obvious inference is: since the horizontal stabilizer has slipped off its jackscrew and become jammed into a descent angle beyond the authority of the elevators to correct, in inverted flight this would push the nose far above ...


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 ...


14

I fly such a plane. My Laser has full inverted systems (oil, gas) and symmetrical airfoils. You're right that when in upright flight the wings are producing lift in the direction away from the wheels and when in inverted flight the lift vector points in the opposite direction. You're also correct that the wings are producing zero lift at 90 degrees of ...


13

When inverted, cut power. As speed bleeds off, gradually move stick forward keep your flight level, the nose will come up quite a bit over the horizon. It is important not to start sinking here as that will prevent the speed coming down low enough. When the stick hits the forward stop, kick in full rudder either way. Enjoy!


12

Any “modern day” piston engine can allow for inverted flight if it has the right equipment on it. The American Champion Citabria with the 7KCAB Inverted Fuel and Oil package along with the American Champion Decathlon are both "Modern Day" aircraft capable of sustained inverted flight. The major differences between the7GCAA and 7KCAB were in the fuel ...


12

Yes they are! Aerobatic aircraft can have symmetrical wing to improve inverted performance. So with these aircraft there is no any problem at all. Other agile aircraft, gliders can fly inverted as well. Of course is far from optimal but possible. Don't forget that lift depends of angle of attack as well. So if you fly inverted angle of attack and drag will ...


11

FedEx 705 underwent extreme maneuvers, even inverted flight. The captain was trying to disorient a hijacker while the first officer fought him hand-to-hand. Here's a dramatization of it. Not sure if it's the best one but there are others. Most of your airfoils are designed to produce lift at 0 angle of attack (a perfectly symmetrical airfoil will not), ...


10

Most aircraft use a cambered airfoil. Such an airfoil only gives you a higher stall speed, otherwise it will just cope fine with prolonged inverted flight. The wing's twist will most likely increase the induced drag since the circulation distribution over span is designed for upright flight, and maybe the airfoil will operate outside of its laminar bucket (...


9

Short answer: Asymmetric airfoils have different positive and negative stall angles, the largest absolute value of the two depends on factors like nose shape and camber. With positive camber (normal and utility aircraft), the negative stall angle can be the largest (in absolute values) but the maximum negative lift available before stall will be smaller than ...


9

Would a plane in 135° roll be using stick-forward to retain altitude? And thus bank in the direction the wheels are pointing? Yes and yes. Let's say you're flying North. You roll inverted, then lift your left wing 45 degrees above the horizon (this is the wing that pointing East, now that you're upside down). You'll experience the usual G forces ...


9

Typically, unless the CG is quite far aft (as is often the case with aircraft designed for aerobatics), lots of forward stick or yoke will be needed to keep the nose high enough for sustained inverted flight. With inadequate forward yoke or stick input, the airspeed may increase very quickly as the flight path curves earthward and altitude is rapidly lost. ...


8

Theoretically ANY airplane can be flown inverted, if you know what you are doing with it and make sure it is loaded properly throughout the maneuver. Boeing test pilot Tex Johnson famously rolled the 707 prototype - twice - during a demo flight for airline executives at the SeaFair hydroplane races on Lake Washington in Seattle. He nearly got fired for the ...


8

I find it hard to make a general answer since the fuel systems could be different between various aircraft, but, according to Jan Roskam's Aircraft Design series (I just had to return the book, but I think it's Part IV in the series) some model of the F/A-18 utilizes the following system which, in sustained inverted flight (or any sustained flight condition ...


5

The easiest way to enter is the same as for an upright spin. Cut engine. Bleed off speed. Keep altitude by pulling gradually. When buffeting indicates approaching stall, push stick decisively forward to mechanical stop and rudder pedals to one side. Same as you would enter a negative snap roll. This is a clean and gentle entry, with a minimum radius, ...


5

I realize you explicitly stated: To clarify: I'm not wondering about engines, fuel systems, air-frame strength etc. Fundamentally there's no reason why those systems cannot be engineered to be robust against inverted flight. But I'm going to answer for part of this because it does seem to be the limiting factor of your question. The main problem ...


5

Level flight (no change in altitude) upside down, with an airfoil with a zero-lift AoA of less than or equal to zero degrees, requires a negative AoA to get upwards lift. This is assuming the AoA is measured in the body frame of the aircraft, aligned with the chord line of the airfoil. Also this assumes there is no thrust/drag or thrust/drag do not ...


4

Yes, based purely on the wing shape an airliner could fly upside down and maintain a straight inverted flight. The lift of the wing is a function of the vertical angle of the airflow, the angle of attack. Image source The picture shows an airfoil pointed upwards, but the same forces apply when the wing nose point downwards. Then turn the picture upside ...


4

It is possible to design one which does but impractical. The PulseWorks simulator, while entertaining, is not realistic and cannot accurately simulate inverted flight. The simulators motion is not made so the sim cabin matches the actual attitude of the real aircraft during maneuvers; rather to induce sensory illusions in the trainee crew which match what ...


4

That depends on how the pilot inverted the aircraft. If they pulled a Tex Johnson and executed a smooth barrel roll everyone would remain in their seats as it is a 1G maneuver. Even the flight attendants pouring drinks wouldn't spill. If the Pilot executed an aileron roll the situation would be quite a bit different...


3

You are basically comparing a situation with positive $\alpha$ (above) with a situation with negative $\alpha$ (below). You could obtain the same situation by pitching down: see how in the second picture your flow direction arrives from above the chord line (in the reference frame of the wing). If your airfoil would have been symmetrical, the critical ...


3

The only case I could find of an airliner flying inverted for any period of time was Alaska Air 261. The jackscrew that set the incidence on the horizontal stabilizer stripped out due to shoddy maintenance, putting the stabilizer in a severe nose down position that elevator and trim input couldn't correct. For a minute or two, the pilots did manage to hold ...


3

Adding on to @Marius's very good answer: Another thing to point out is - there simply isn't a need for a fighter jet to fly around inverted for long periods of time (outside of a Blue Angels show!). It's uncomfortable for the aircrew, and doesn't really do anything tactically. Therefore, it's not worth the extra expense/maintenance. As a side note, the ...


3

I fly competition aerobatics. The only setup I've seen is some flavor of Lycoming engine with extra bits for fuel (flop tube in a header tank) and oil (Christen inverted oil system). Your friend is correct that some (most? all? -- I don't know) radials can handle inverted flight. Make sure there's a way to ensure continuous fuel and oil delivery to all the ...


2

If I look from the end of the right wing in direction of the fuselage, I see the air moving around the wing counterclockwise, while inverted it must spin clockwise. Note you could do the same thing simply by putting the aircraft into a dive. All you need is for the angle of attack to be negative. As it passes through zero angle of attack, the lift falls ...


2

Yes. This video at 0:50 shows a heli climbing into a loop, labeled at the top as 1.4 G and 25 knots, so it's still in forward flight when it reaches inverted flight. The view from inside the cabin at 0:58 confirms pitching without rolling. (At 1:26 the heli does what's labeled as a front flip at low G's, but that includes a lot of roll too.) The pilot is ...


2

A concise way to describe the situation is that during sustained inverted flight, if the aircraft is banked away from wings-level inverted, the flight path will curve toward the wingtip that is closer to the earth. This is a bit odd because the flight path ends up curving AWAY from the direction of the initial roll, i.e. away from the direction that the ...


2

Like it has been said here it is very difficult to simulate g-forces outside of the common civil flight envelope. But it is possible! I have built one, you can watch videos of it on YouTube here, and here. Like Zeus said, even with this 2DOF 360° you will feel "wrong" g's very often, e.g., banking with 90° feels like a 1 g rudder slide. And a loop feels ...


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