All Thumbs

I've just picked up a set of Ernst rudders and noticed they can be made to retract. That's kind of cool and I'm thinking about setting them up to do that.

In the meantime, I know nothing about the proper retract procedures. My current (and first) setup simply has the water rudder swinging freely.

So....when do you retract them and when do you put them down? What is the proper way to do this? Obviously they are down when taxiing and surely up when flying. But at what point in the takeoff do you raise them? At the beginning? Shortly after liftoff? Once you are on the step? (that would make for a busy takeoff). And then obviously I'd like to know the reverse when it comes to landing.

I don't know if there's any difference in procedures between full scale and R/C models, but if there's a discrepency I'd love to know that too.

Thanks for any info...

seaplane

All Thumbs, the water rudders should be raised just before your take off run......Seaplane

All Thumbs

And since that's the case...they should be up for landing. From what you say then, I suppose the simplest way to put this is: The water rudders are used, and therefore down, only for taxiing...at all other times they're retracted. Simple enough, thanks for the info.

JimCasey

My Feedback: (1)

If you pull the throttle back to idle and retract the water rudder(s) and don't do anything else, the plane will weathervane directly into the wind.

Get a copy of "Wonderful World of FLoats" from the EAA. (VHS, about 2 hours) They go through getting a full-scale seaplane cert, and water rudder procedures are emphasized.

All Thumbs

I think that video is a great suggestion. I've just ordered it from the EAA site (luckily I still have a player). It will arrive too late to help with this season but it doesn't matter. It should add to the fun of this whole thing. I've got enough info to practice with until the November winds start ripping through Northeast Ohio.

Now...all I've got to do is figure out how I'm going to do the whole retractable thing anyway. I've installed the new rudders since starting this thread and started thinking how best to do this. It's not exactly roomy in my Superstar's fuselage, but I'll come up with something. I probably won't retract right away but I'd like to have it for the spring (the more scale I can fly the better I like it). For the near term I'm going to let them hang freely.

Of course the best scale flying comes with a scale plane, but I'm patient. This one is fun to modify and learn from. By the time I start on a better plane I'll have a real good handle on everything.

Thanks again guys.

BillHarris

And I'd suppose that you need to be very careful about not using the rudder(s) during the takeoff or landing runs if you do not have retractible rudders...

--Bill

All Thumbs

Actually, from a previous thread, I was given the answer by several people not to worry so much about using the rudder. I was afraid to use it due to some stuff I'd read, but my takeoffs have improved tremendously once I threw that notion out (I've never flown with retractibles yet). If you're correctly pointing into the wind you won't need much correction anyway, but if correction is needed...use that rudder control. When I was unsure at the start, I ended up with a few "S" shaped takeoff runs. It seems to me that the water rudders complicate things a bit but so far it doesn't seem "too overly" critical that they're there...as long as you maintain control of your model.

For the most part, I only wanted to retract to do this a little better and more scale-like. Keep in mind I'm new (~30 flights with about 60 takeoffs and landings) and I'm only flying a 7 lb plane, so I'm not the last word. But I was originally being "very careful not to use rudder" in my takeoffs and I came very close to wiping my plane out (which prompted my previous thread). I'm now very sure to keep control of the rudder to keep the takeoff run straight the same as a land run. With the rudders retracted I probably won't have to worry about that as much since I won't transition from having water rudders...to not having them...halfway through the takeoff run (at least that's what I'm taking away from the answers above).

Unless somebody corrects me here, my limited experience says that it's actually more important to use rudder control when you don't have retracts.

JimCasey

My Feedback: (1)

You've pretty much got it. Just like everybody who is paying attention will build in a low rate to his nose wheel (or tailwheel), you don't want the water rudders to have too much authority. Your mod posted earlier where you reduced the size of the rudders and left them free-swinging so they will self-retract was demonstrated to be beneficial. Even if your rudders are not retractible, they should not be in the water after you advance the throttle for the takeoff run. That's why I tell people to limit them to 1/2" lower than the transom of the float.

All Thumbs

I think I've slowly begun to learn the wisdom of this advice. I'm doing quite fine with my "self-retracting" rudders as you put it, but half-inchers would definitely take them out of play completely when up on step.

Just for grins, a friend of mine took an excellant fast sequence of pictures of one of my takeoffs. I think they do a good job of illustrating some of the points you guys have made amongst the threads I've been involved in.

The first one shows the plane up on step. Keep in mind my transoms are 2" high in the middle and 1 1/2" high on the ends...for reference. These pics are cropped and zoomed in so they're just a little fuzzy.

The rudder in this picture is pushed up well out of the water. Still, just a little bit remains. I'm sure it doesn't steer as much as it causes a little drag in the water (these pics are pre-Ernst). At any rate, the effect isn't major and I can very easily keep control with rudder as I normally do on land.

But I think you can see that if the rudder were only 1/2" below the transom, it would be fully out of the water and then there would be no drag issue at all.

The second picture shows the plane just after it leaves the water. Everything is airborne...except the water rudder. It's still not causing a major problem, but it's there. You can see it swinging down just enough to maintain contact. The water's doing a good job of pushing it away to not cause steering problems...but there's still that tiny bit of off-center drag. With experience now, I'm controlling that pretty easily. Having two rudders should eliminate the offset drag (I have more than enough power to get airborne).

The last picture shows the plane well up in the air, and you can see that the water rudder is now fully down (I put this in mostly to compare rudder position with the first pic). You can see that the rudder rests almostly completely below the transom.

One issue I think I've noticed with a swinging rudder, is that a fast taxi seems to turn less effectively. For now, I'm guessing that the water pressure pushes the rudder up a little bit...but that's unconfirmed. Most of my taxiing is slow, but sometimes I get a little impatient . Still, I can "run" off to my takeoff position then cut the power to turn into the wind (and no, I'm never going real fast...I learned the hard way not to taxi on step). None of the issues I'm having are show stoppers anymore but I'll definitely be looking to experiment and do this better and better. Fun stuff.

If I don't come up with a clean, worthwhile installation idea for retracts on this small trainer, I'll do one of two things. Either I'll leave the rudders free swinging, or else I'll cut them down to the 1/2" and attach the rubberbands to hold the rudders in place (for full taxiing use).

Anyhow, sorry bout the long post...but I really liked the pictures my buddy took!