Hello All,

Well, I have attached my pushrods to both the elevator and the rudder. The elevator looks pretty good. However, it appears as though the rudder doesn't have enough room to move when the servo extends its arm fully in either direction. I placed the rudder too close to the fin and now the fin is partially in the way.

Thoughts?? I am of the mindset that I will need to "trim" the corners of the fin in order to give the rudder the room it needs to move. This appears as though it will be a pain (since it is already covered). Has anybody encountered this situation before?? Anything that you could share would be graciously accepted.

Thanks in advance!!!

Dan

You really want to get the rudder as close to the fin as possible to eliminate any gap on the hinge line. However you also need to bevel the leading edge of rudder (and the other control surfaces) anywhere from 30 to 45 degrees. This provides the room needed for the control surface to move.

This is normally done before the surface is covered and is usually done with a sanding block held at the correct angle on the leading edge of the surface. Ideally you mark the centerline (the little cheap plastic hinge line marking tools work well for this - just mark the whole leading edge instead of just where the hinge will go) and then sand at a 30 to 45 degree angle until you reach the center line.

Some kits such as some of the Goldberg kits, also supply a handy little plywood jigs with the proper angles for the bevels. You glue the three parts of the jig together, attach sandpaper to the face of it and then run it along the leading edge of the surface. It gives a very accurate angle and a very straight edge and the little jigs are worth throwing in the tool box for other models.

In your case you will need to remove the covering first. You can either recovere the whole rudder or you can trim the covering off to about 1/4" aft of the leading edge, sand the proper angle and then add a single strip of covering over the leading edge. You will want a 1/4 inch overlap on each side so the strip will need to be an inch or so wide. If the edges are cut straight it will not be that noticeable.

On the other hand, you normally do not need full rudder travel and an inch of movement (measured at the trailing edge) is usually more than enough. Your aircraft may call for less travel as well. I have seen rudder travels specified as low as 3/8 of an inch on some aircraft so your problem may not really be a problem at all.

Hhhmmm ... I wish I knew about sanding the rear corners of the fin beforehand!! Ah well, gotta learn somewhere!! Thanks for the info ... it appears as though "2 paths diverge ..." ...

1) strip of the skin and sand away

-or-

2) leave things well enough alone

What I do from here depends on the answer to the next question:

When I move the rudder to either side, I see the fin flex (aka - from the rudder pushing on it). Is that a problem?? Or is that something that I can "live with".

I will most likely go the way of option #1.

Thanks!!!

- Dan

That is a problem. It will either break the hinges, the control horn or the rudder. You just need to reduce the
throw one of three ways. 1) move the linkage closer to the center of the servo arm. 2) move the linkage
farther out on the control horn. 3) some radios allow you to adjust the amount of travel. Or do a combo of all
three. Please dont fly it that way. The drain on your battery is very high when the servo is flexing the
rudder. if you decide not to bevel the edge be sure to seal the air gap with a piece of monocoat.
later daveo

OK ...

I agree with you on not flying my plane with a flexing tail fin.

I appreciate your advice. Would it be wiser, or better stated -- the best option, to either:

a) Trim the corners off of the tail fin

b) reduce the throw (utilizing a combo of all 3 methods stated)

- or -

c) a combination of a) AND b)

-------------------

Personally, I like the idea of simply reducing the throw. However, how much travel do I actually need?? Further, being a beginner, what is the best way to measure the travel??

Thanks much!

- Dan

Dan , let's start with how much throw. You plane should have a recomondation on the plans
or in the instruction book. If you can get enough throw without it binding leave it. But , keep in mind the
nose gear also runs off the same servo. To keep enough travel to steer you should start trying to reduce
it mechanically. That is by moving your linkedge.Start on the servo by moving inward. Then go to the control
horn and move out. If that dosn't fix it go into your radio programing. And remember that you can increase
your stearing by moving the linkedge the oposite way you reduced the rudder. The throw is always
measured at the biggest part of the surface. If you cant get the enough throw then worry about triming the
front of the rudder or back of the fin. I think it would be best to unhook the clevis from the rudder control horn
and then move it with your hand to see if there is enough throw. If there is then do what I said at the top
of this answer. I mesure the throw with a triange on the rudder. Just push the rudder till it starts to bind.
stand up the triange were it touches the rudder, then center the rudder and mesure the gap between the
triangle and the rudder.
I hope I have answered all your questions, if not post back.
later daveo

Thanks once again!!!

I really appreciate your feedback. I'll check that out this weekend. Take care!

if you get the required amount of rudder 'throw' out of it then all you need to do is ajust the rod closer to the center of the servo arm or vice 'a' versa (as noted above).. if you dont get enough throw out of it then you need to work on it more... its balsa wood man, the stuff is light weight.. when I first started building I ran into that problem too... and instead of wondering forever how to fix my 30 dollar airplane, I took a straight edge and laid it in the hinge line and folded the rudder over a little bit then switched sides and did the same thing... Doing that a few times on both sides should smash the light wood down enough to move more than you got now... TYhere are a number of things you can do to fix this problem, but one thing you DO NOT want to do is try and fly an airplane in a poor condition... who knows what might happen... the servo buzz at all?? That will drain the battery down faster (again, noted above) or if you have servos with plastic gears in them, you might strip a gear... I saw that happen once... that guy didnt land his 500 dollar plane that day [img]i/expressions/face-icon-small-happy.gif[/img]

What you really need is to take the model to the local flying field, and get an experienced modeler to LOOK at it, inspecting the rudder problem especially, but also looking for other problems (which almost certainly will be there...)

When a beginner brings a model to our club's field and I am present, 99% of the time he is sent to ME! I find an average of 4 MAJOR errors on any model built by a beginner with no assistance... Often, I can assist n the corrections at the field, and have the plane flyng the same day.

Then comes the problem of learning to fly it. A beginner (strike 1) starts with an untrimmed airplane (strike 2) then, when he gets the engine started (strike 3) ... he very soon has a bag of toothpicks.

Get help. Visit http://modelaircraft.org/templates/a...36F5937164E082 That's the AMA club locator page for Massechusetts. I expect there's several clubs fairly close to you... Do a search on the first 3 digits of your zip code. (Edit, Find {or ctrl+F} in Internet Explorer) The first 3 digits should get you within appx 50 mi. (the first 4 usually gets within your city) Repeat the find... there may be a few fairly close. [img]i/expressions/face-icon-small-wink.gif[/img]