Return Springs on Rudder Pedals

[ToddP]

As mentioned in another thread, the late Chuck Irby suffered an accident because of an improperly swaged cable and that fact that he had return springs on his rudder pedals. Now the same thing has happened to Paul Bruty.

On my dominator, even though my cables are properly swaged, I have never put return springs on my pedals because of the accident Chuck Irby had. I've gone back and forth on this at least once with Ron and would like to know others opinions. The spring returns are a convenience, however if there is any kind of malfunction with a cable, the rudder will fully deflect the opposite direction. Ron argued that a person should have enough sense to lift the pedal with their foot. I personally don't think there are many people that would realize the problem quick enough to act accordingly.

What are your thoughts?

[mcbirdman]

I think that a rudder return spring on both pedals but adjusted for no tension at straight up pedal should not be a problem. A stiff enough spring should be enough to self center the rudder pedal with no additional bias and should be just fine.

In normal use a left rudder input will stretch the right spring providing force that will try to return the left rudder. In the case of a failure there is no bias on either sides......

This seems like a logical way to do things without setting yourself up for the situation you mentioned above..... and I am going to recheck the exact same thing with my setup.

[birdy]

Ron has a point, if the pilot is relaxed and experianced enough to think of do'n it, not to mention have enough alt.
I'v got a different setup from everybody[wot else] but I do also have springs returning me pedals,.......... but only as far as neutral, or streight ahead.
If I blew a cable the springs will only pull on the remaining one till the rudder is back to streight, not opposite lock.The fin would do a good enough job of keep'n me nose point'n the way I'm go'n for an emergency drop in.[Because of my setup, if I pulled back the other peddal, nothn would happen, broken cable or not.]

[mceagle]

Rudder pedal springs are only supposed to be light springs, just strong enough to take the slack out of the cable to stop it fouling or catching on airframe bolts etc. when the gyro is unattended. It would have to be a very strong spring to activate the rudder against the slipstream, especially with a fixed fin. The pressure gradient on the rudder increases with deflection and the spring pressure decreases, making it almost impossible for a correctly set up spring to deflect the rudder enough to be unflyable.
If you dont like to take the chance of a spring pulling on a cable after failure, then instead of mounting the springs on the airframe, mount them on each end of a bellcrank, pivoted in the middle. A cable failure then would release the spring on the other pedal.

[Mike Hook]

I have seen what I guess is called a anti-servo tab on the rudder on the Sparrow Hawk would this not also help to return the rudder to a straight line as well as what every one else suggested , a light spring tension.

Mike

[mcbirdman]

It wouldn't matter if the spring was strong or not if it is adjusted so that at zero tension it would be straight up pedal as I suggested. I meant strong enough to help center it so that you could instantly return back to nuetral and have a positive feeling of such. Too soft and you won't feel anything and just the weight of your foot resting on the pedals could overcome the springs unintentionally. Not stiff enough to tire you out or make you have to stand on it or anything either......

To me it is similiar to a tactile keyboard and a cheap one that you can't tell if you actually pushed a key. Not having to push it hard but you know when you did......

[BUD ONEAL]

A properly built dominator tall tail will have a anti servo tab to keep the nose straight ahead should this happen. I did not install mine because it would hit the dirt and bend the wayI set mine up. {my keel is to short and I set the rudder way back to get all the leverage that I could} so the anti servo had to come off.The dominator tall sets so that the prop blast will keep it straight behind also. This could be a worry though. We all arn't as young and as quick to think as Ron. He is a great pilot!

[Harry_S.]

I don't mean to step on anyones toes here but...I've never used *rudder return springs* on any of my gyros, nor do I see a need or purpose for using them. :confused:

Can someone explain to this old codger why you would install them and for what purpose?! Is this considered a safety of flight item?


Cheers :)

[Brent_Brown]

My springs are for the nose wheel and not the rudder. If a cable would brake on my gyro I would just try my best to land right into the wind. My rudder would be free to swing back to center.

[Doug Riley]

I think of the springs in the same way as Tim McClure -- as a device to keep the cables from sagging and fouling other parts of the craft. Light springs are enough for this purpose. The rudder should be designed so that it is aerodynamically self-centering, without the help of the springs. Bensen-style rudders naturally have this quality in abundance, while an all-flying vertical stab pivoted at its aerodynamic center (such as the Dominator's) will require an anti-servo tab to do the same job.

One way to tension the cables without running into Paul's problem is to connect the pedals together with a length of cable a couple feet long, run forward from the top of one pedal, and then looped back to the other. Put a pulley in the middle (bight) of this cable where it doubles back. Attach the pulley to the frame with a tension spring. This way, if one cable breaks, the spring-pulley assembly will pull that pedal forward until the spring goes slack. The spring then won't be able to deflect the other pedal.

[mcbirdman]

Yea, you could do all that or even simpler.....

Install the rudder springs so that the springs are under no load at pedal straight up as I mentioned before.


The spring size has nothing to do with it. As far as stiffness, I am just thinking about how just resting the weight of your feet on pedals can introduce movement. A little stiffer spring is less sensitive to slightly different pressures you might be placing on the pedals. I am thinking about the fact that one heel might be a little closer or farther from the pedal and such....

But for whatever preference, a stiff or lighter weight spring properly adjusted will NOT cause a control problem during a cable failure.

[jos]

Hello,

The rudder should return to neutral position by airflow not by springs.
All the machines I had turned to zero rudder without springs.
No springs less complex, less heavy, safer and lighter.


JOS

[mcbirdman]

The springs keep the cables tight and not slack without trying to pull the rudder past nuetral. Kind of like keeping your line tight when fishing. Don't want your lines hanging slack to get all knotted up if they are long when it is time to take action. On a tail dragger you have at least 13' of cable down both sides. The spring keeps the slack out so when you push the pedal at any speed the cable is already taught.

On landing with a stronger spring the pedals will center to nuetral a bit better than almost center..... On tail draggers we want the tail wheel to be straight and this subtle increased tendency to nuetral seems like it would help assure a straighter, easier track when taxing at slow speeds while helping make sure the wheel is straight on landing. These are just some other things worth thinking about. These things are all obtainable with simply adjusting the springs to nuetral.