Instances of reversed controls

[corethatthermal]

When in aviation does one experience reversed controls? Using a non-aviation example ( but related to helicopters and prop planes ) is when you want to turn your motorcycle at speed around a RH corner, you initially turn the handlebar to the Left ! One aviation example coming to my mind is the Concorde when a pitch up is commanded on landing and the plane initially descends!

[waterdog]

I think in your example of the motorcycle it's not so much an example of control reversal but something that seems counterintuitive. The bike turns right at high speed because it "falls" into the corner when you slightly turn the wheel the opposite way. But the physics make sense.
The only true examples of control reversal that I know of is when planes hit extreme speeds...I have read reports when they were testing mach speeds at high altitude and planes would experience control reversal if you pitched up to slow down the dive would worsen, but if you pushed forward the plane would pitch up and you could ease out of the dive. I think it was first experienced when they were trying to set the altitude record in a spitfire and got somewhere close to FL 470 before things came undone, the pilot managed to get the plane under control but there was a true flight reversal. There are lots of other times where things just feel counterintuitive tho, like when you are in a 45 degree banked turn and have to add opposite aileron to maintain a constant bank and prevent going past 45 degrees. I've never read about a true control reversal when it comes to the ailerons or rudder, just the elevator.

[photofly]

The Fokker D8 had a tendency at speed to roll left when the stick was moved to the right; the two wing spars were such that the load applied by the aileron would cause the wing twist leading to a decrease in lift on the side where the aileron was depressed. Eventually there was a divergent situation and the wing was twisted completely off.

[Big Pistons Forever]

Control reversal is unlikely to be experienced in a modern airplane. However performance reversal occurs in the slow flight regime and has bitten many unprepared pilots.

Sadly there have been many accidents caused by flight controls reinstalled backwards. I had a significant emotional event when the elevator trim on a high performance single engine was hooked up backwards. Shame on me for not finding this on the DI.

If any significant maintenance work was performed on any flight control, it is very important that you verify the correct movement

[corethatthermal]

The bike turns right at high speed because it "falls" into the corner when you slightly turn the wheel the opposite way.

This is happening, but what is also happening is this : In a RH turn, you steer Left, Gyroscopic precession acting on the back of the tire pushing it right and on the front of the tire pushing it left reacts 90 degrees from the force input, therefore the force is acting on the top of the tire pushing it to the right and on the bottom of the tire pushing it to the left making the motorcycle bank to the right. Try this in practice with a bicycle tire moving and holding it by the axle, then try to turn it left. If too much turn force is fed into the handlebar, the rider will need to turn the handlebar to the right ( counterintuitive) and this action causes the bike to upright itself by the same gyroscopic law of nature. Of course, the same thing you described above is happening in the reverse but I believe Gyro effect forces are much more than inertial effects causing tilt.

[corethatthermal]

Raising the tail of a taildragger causes the nose to turn to the left in a right turning prop due to the same effect.Abruptly trying to stop this Left turning causes the a/c, you guessed it, to nose down more!

[PilotDAR]

Generally, modern planes have control mechanisms which are designed to make backward connection simply impossible (opposing tunbuckle threads or uneven cable lengths being the most common). So backward primary flight controls are happily now rare. The pilot should still check though. What I have found a few times, are controls which are limited, and should not be:

I've had a Cessna 150 nosewheel steering systems "maintained" so as to be misinstalled, resulting in rudder travel in one direction (I forget which way) being greatly reduced. I've had a bent aileron pushrod on a Cessna 182, which resulted in an aileron neutral position lower down than should have been (poor man's Roberston STOL aileron droop, which I should have noticed on the DI). I once picked up a Cessna 150, which had been parked for eight months. Sure the control lock had been installed. What I failed to notice was that a burr had formed on the control wheel tube at the control lock hole, which was not a problem in normal flight, but with full flaps selected then passed into the control wheel bearing, and jammed, so I had trouble applying up elevator to flare. 'Wrong time to find that problem! I've had the elevator trim tab limits of a Cessna 206 reversed, such that where I should have had 25 degrees of tab movement, I only had 5 (you really need those other 20 degrees in a 206!), to then find that the angle of incidence of the H stab was 1 degree wrong, and it's not adjustable! I test flew the very first Zenith 701 STOL back in the mid '80's to find that extension of the flaperons used up aileron travel, which was much more needed at the slower speeds achieved with the flaps extended! I had to vigorously rudder a few turns to get it around, while I returned it to Kleinburg to report to Chris what I had found. I've had the flaps of a Cessna 180 jam at 20 during a water touch and go, having to fly home with 20, 'cause they would not move, and I did not want to induce asymmetry by fighting them! And, I found during flight testing, that at certain flap settings, the Siai Marchetti 1019 (an Italian turbine version of the Cessna Bid Dog) will run out of nose down elevator travel, while the nose continues to pitch up.

So, yes check full and free controls, paying extra attention to the "full" part of that check! If in doubt, and I have done it for maintenance check flights) ask to see the AME do a control limit check for you. All control travel limits are specified on the type certificate date sheet foe every aircraft.

[Heliian]

Check your brakes individually after service, saw one with Hydraulic lines reversed. Pilots never noticed as they mostly double braked. Could have caused a ground accident though.

[Ki-ll]

http://avherald.com/h?article=4c04438e

[pelmet]

Based on the initial posters description of a vehicle that had no faults......

I think it is typically high speed where this can be expected in certain aircraft where the force of air pushing on aileron deflection is high enough to twist the wing(which one could do on the ground as well by providing a force in a similar manner). Apparently the B-47 with its long wings had some sort of issue with this along with the Spitfire.

I talked to a test pilot who got a ride on a B-52(which is similar to the B-52). Perhaps it was the earlier model with ailerons instead of spoilers. The pilot flying said to watch the wing as he put in roll control and there was significant reactive movement of the wing. Of course, they are long, flexiblw wings.

[North Shore]

The bike turns right at high speed because it "falls" into the corner when you slightly turn the wheel the opposite way.

This is happening, but what is also happening is this : In a RH turn, you steer Left, Gyroscopic precession acting on the back of the tire pushing it right and on the front of the tire pushing it left reacts 90 degrees from the force input, therefore the force is acting on the top of the tire pushing it to the right and on the bottom of the tire pushing it to the left making the motorcycle bank to the right. Try this in practice with a bicycle tire moving and holding it by the axle, then try to turn it left. If too much turn force is fed into the handlebar, the rider will need to turn the handlebar to the right ( counterintuitive) and this action causes the bike to upright itself by the same gyroscopic law of nature. Of course, the same thing you described above is happening in the reverse but I believe Gyro effect forces are much more than inertial effects causing tilt.

Is that 'control reversal' though? I see it as an un-intuitive way to get your bike to do what you want it to do....'control reversal' to my mind would be pushing left, and then going left...

[corethatthermal]

Is that 'control reversal' though? I see it as an un-intuitive way to get your bike to do what you want it to do....'control reversal' to my mind would be pushing left, and then going left...

On a bicycle, you turn the handlebar to the left to make a left turn, on a motorcycle you do the same at walking pace. At highway speed, you do the opposite ( reversed? )

[corethatthermal]

Ok, Here is another bird brained idea by the Core! What if one were to reverse the aileron controls ( intentionally and safely and legally ) and then become proficient. This A/C could be used for reverse control training ! Also, have the elevator controls reversed in the same manner !

[corethatthermal]

No one ever plans to fly a control reversed plane just like no one ever plans to flip a floatplane and crawl out upside down !

[photofly]

Ok, Here is another bird brained idea by the Core! What if one were to reverse the aileron controls ( intentionally and safely and legally ) and then become proficient. This A/C could be used for reverse control training ! Also, have the elevator controls reversed in the same manner !

I'm tempted to say, go and try it, and come back and tell us how it went, but I quite like your posts and I'd be said if they stopped.

[Conflicting Traffic]

Ok, Here is another bird brained idea by the Core! What if one were to reverse the aileron controls ( intentionally and safely and legally ) and then become proficient. This A/C could be used for reverse control training ! Also, have the elevator controls reversed in the same manner !

This has been done for a bicycle: https://www.youtube.com/watch?v=MFzDaBzBlL0. It might be a neat little training/education/psychology experiment (assuming it could be done safely, maybe in a sim?). But in the context of aviation, it doesn't seem very useful.

As for actually reversed control on an aircraft, control reversal is a high-speed phenomenon, and is one of the criteria that Vne is based on.

[North Shore]

Is that 'control reversal' though? I see it as an un-intuitive way to get your bike to do what you want it to do....'control reversal' to my mind would be pushing left, and then going left...

On a bicycle, you turn the handlebar to the left to make a left turn, on a motorcycle you do the same at walking pace. At highway speed, you do the opposite ( reversed? )

Try pedalling your bike a little faster the physics are the same as a motorcycle...

[PilotDAR]

control reversal is a high-speed phenomenon, and is one of the criteria that Vne is based on.

It is true that any tendency for control reversal is not permitted up to Vne, but its not really what Vne is based on, it just may not occur up to Vne, as a number of other things. The control reversal mentioned in that design requirement is a stability or thin wing twisting situation, rather than a maintenance error. Any situation where control reversal occurred at high speed would be preceded by instability which was disqualifying for certification. The same design requirement also mentions control force reversal, which is a different thing.

In GA airplanes, a tendency toward control force reversal at high speed could be a slight concern, and is certainly evaluated during certification testing. The standard allows for a little. I have experienced it during high speed testing, and slight trimming was all that was required. Think of it as a center of pressure shift, like someone walking in the cabin. Remember though, what when you're approaching high speed, you're not really putting a lot of force into the controls, you're being very gentle! Control reversal itself at high speed is not even a remote risk for a certified plane. Vne is primarily predicated on flutter, vibration and buffet margin. Bear in mind that every certified plane has been tested to at least 110% of it's Vne, and found to be safe and sound at that speed.

The closest a pilot is likely to ever get to a control reversal (faulty maintenance excluded) would be when you're fooling around at the point of the stall, and find that the ailerons are completely ineffective ('cause they're stalled), or, for helicopter pilots, when you experience loss of tail rotor effect, because tail rotor blades have stalled.

[TG]

Part of the CAF pilot selection test in the late 80's (not sure if they still do it) Was to put you in a very basic link trainer and then ask you, while sitting in it, to pinpoint such and such targets painted on a wall.
Your first go was with one control at the time. Second, pitch, roll, yaw all together.

Except that to put everybody on par, they had the ailerons reversed
It surprised me initially but I got the hand of it relatively quickly, probably like everyone else with zero flying time experience and a little bit of hands and feet coordinations.

Which brings me to this guy who was boasting is 1000TT before that test, saying that he would "Ace it" no problem.



He stepped out of the room crying.

[corethatthermal]

Doin the dunkin would approximate being upside down in a floatplane,,, there is some risk there but very little , same as my scenario with reversed controls . Doin the mcas "runaway trim" scenario in a sim would NOT incur any additional risk but would actually reduce risk in flight!