Water Rudders

[SeanMountainous]

Hey everyone,

I've noticed recently a few floats have water rudders that seem to hang really far down into the water even when they're retracted... Is there any reason for this? Are they set up wrong? Seems like it would make beaching impossible without bending them.

Thanks

SeanMountainous

[Heliian]

I've seen that before with amphibs from a manufacturer. Other setups I've seen look like they intentionally want you to damage them. Sometimes its lazy rigging or bent linkages.

Just man up and take them off. Jk unless it's a twin.

[Rowdy]

Some of the beavers on 4930's have bigger rudders.. also, some droop (not rigged right)

[seasonaldriver]

I fly on the 8000's which have water rudders that don't retract up very far by design. Backing into a beach you have to be very careful to straighten them before impact with the sand. Otherwise the AME's get really annoyed at you for bending "their" plane.

[SeanMountainous]

Any idea why they wouldn't just design it to retract a little bit further? Seems like a silly thing to have to deal with everyday...

[ragbagflyer]

Different aircraft have different systems but when the water rudders are retracted the droop is typically a factor of how the pull up cable is adjusted. There's usually a turnbuckle that allows you to tweak the tension but beyond that I think you'll have to lengthen or shorten the cable. On a beaver you can just shorten or lengthen the cord attached to the handle in the cockpit. Also, depending on how the pulleys are set up you may have to always have a slight amount of tension on the pull up cables to keep them seated on the pulleys. This is key on the Otter I fly; not enough tension and the cable comes off the pulleys, too much tension and the clutch that connects the water rudders to the rudder pedals/air rudder won't engage when you drop the water rudders.

What's just as important then where they sit when they're retracted is where they sit when they are extended because you want the water rudder to sit against the stop when it's down. If it isn't against the stop you'll end up with less of the water rudder forward of the pivot point of the rudder which makes it harder to keep the aircraft in a turn on the water. The stops can be shimmed to control exactly how much of the rudder is forward of the pivot point in the down position.

So what if the rudders are where you want them when they are down, but not high enough when they are up? To create more travel in the water rudder retraction with a given amount of cable travel you can redrill the hole on the water rudder and reattach the pull up cable closer to the water rudder post.

I worked for one fellow who kept a lot of droop in the rudders on the beavers because he thought it kept them more out of the slip stream in cruise so that they were working less against the air rudder. There's certainly a bit of truth to that but how much of a difference it actually makes is debatable. We didn't do a lot of beaching so it wasn't really a big deal.

At my primary summer job I do as many beachings as dockings and I wouldn't want the rudders hanging extra low, but even in a relatively higher position they will still contact the beach at the same time as the float with any kind of load so you still want to pull the aircraft against the shore with the water rudders as parallel to the float as possible, or if reversing against the shore, contact the beach as gingerly as possible.

So to make a long story short, it's a bit of an art and that's without even touching on the steering adjustments. The best water rudder tuning tends to come from the old time engineers who maintain many of a given aircraft type for a given company so you get more feedback on the fine tuning and a larger sample size to compare against. It helps if the AMO is internal to the operation so that the owner of the OC isn't paying 100 backs an hour for somebody to make adjustments that may or may not work.

[SeanMountainous]

Ok perfect, thanks for the wisdom guys!


Sean