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Rudder Offset Empty Rudder Offset

Post  Cribbs74 Wed Apr 10, 2013 9:13 am

For quite some time I have been confused about rudder offset. I finally have some first hand experience on how it affects the plane.

I recently built a baby Ringmaster that flew like a dead fish through the manouvers. Loss of tension and lazy stunts etc. I had previously asked a seasoned flyer and was told that you should build for no offset, but if you are having tension problems then dial some rudder offset until the problem goes away.

I decided to try this on the BRM and it was a different plane afterwards. Pulled much harder in level flight and I was able to loop without loss of tension.

So to sum things up........ Rudder offset is not needed unless you have a lack of line tension. Keep in mind you should ensure you have adequate engine offset and yoir leadouts are in the correct spot first. If all that is good and you still have problems try some rudder!!!!

Hope that helps someone. It sure helped me.

Ron
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Rudder Offset Empty Re: Rudder Offset

Post  SuperDave Wed Apr 10, 2013 10:25 am

Too much offset, either engine or rudder, can lead to the "crabbing effect" where the plane appears to fly slightly sideways which is not desireable for several reasons not the least of which is too much of the planes "flyability" is being detracted.

Seeingly each plane and engine combo has it's own "sweet spot" which can only be found through experimentation. But that's the task of "tuning" and when you get it right
you'll achieve optimal fly performance.

Ain't it fun?

SD
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Post  pkrankow Wed Apr 10, 2013 5:38 pm

I just hate cutting rudders off to re-do them...

Phil
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Post  Cribbs74 Wed Apr 10, 2013 6:05 pm

pkrankow wrote:I just hate cutting rudders off to re-do them...

Phil

Me too, especially when they are ultracoted and have decals on them. I guess the best bet would be to add some to begin with. I am beginning to think the old plans were drawn that way for a reason.

Ron
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Post  SuperDave Wed Apr 10, 2013 6:16 pm

Ron:

"I am beginning to think the old plans were drawn that way for a reason."

I have hope for you yet. Laughing

SD

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Post  Cribbs74 Wed Apr 10, 2013 7:01 pm

SuperDave wrote:Ron:

"I am beginning to think the old plans were drawn that way for a reason."

I have hope for you yet. Laughing

SD


I am learning Dave! I have to redo the rudder on the Ringmaster as well. I see no reason for it to come in on a rich run. When the Fox is on song it pulls like crazy.
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Rudder Offset Empty Re: Rudder Offset

Post  gcb Wed Apr 10, 2013 7:31 pm

IMHO build the plane to fly straight. Since you are tethering it with lines you are altering its course to make it fly in a circle. Rather than rudder or engine offset, make the lead-out position adjustable so you can keep it tangent to the circle by compensating for various amounts of line drag.

The old plans had excessive engine and rudder offset "just in case" the laws of physics did not work. Some designers said also that "back in the day" they would cut out lead-outs and move them to the best position. Those lead-out positions were for a specific line diameter and length.

BTW, if you use engine offset to maintain line tension you will be in for a surprise when the engine quits.

Just one opinion, individual results may vary.

George
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Rudder Offset Empty Re: Rudder Offset

Post  Ken Cook Wed Apr 10, 2013 8:11 pm

Why your Ring came in is still a mystery. I can say that it sometimes happens and I'm sure it's happened to all of us in control line at one point. Does it do this all the time? If you launched rich it's quite possible the wind possibly grabbed and lifted the outboard wing high. Keep in mind that the Ring flies better on actual eyelet to eyelet length lines which are approx 58' long. If your using any prefabricated lines they're possibly oversized. I've seen manufacturers claim 60' and the eyelet to eyelet length was 62'+. You now add the inboard wing of the Ring which is an additional 21" and you really have an excessive amount of line your dragging around. When flying planes like your Ring and others like the Shoestring, a custom set of lines like I suggested which would be 58' eyelet to eyelet would certainly be in order.

I don't subscribe to the rudder offset theory and I don't feel it has any beneficial benefits as it creates more negatives than positives. If the plane is yawing outboard, this also has an affect on your fuel pickup in your tank. This now requires the rear of the tank to be shimmed outboard. Rudder offset slows the plane and seeing that all my racing planes and combat planes have no rudders, it only leads me to believe that the commonality between all of them would be speed.

Is the Ringmaster flying tip high in level flight? Is it flying tip low in inverted flight? If the wing does indeed have a warp within it, it could certainly create this problem. When in doubt, I keep small pieces of aluminum with me and clear packing tape. The aluminum is tin enough it can be bent by hand and this can be used as a area tab or a trim tab. If you suspect the wing is flying tip high this can be installed until you can twist the wing as needed. Here is one on my Ring. This is a foam winged Ringmaster and during the covering process you can easily twist this wing. Ken
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Post  Cribbs74 Wed Apr 10, 2013 8:49 pm

Ken,

I don't know how long the lines are to be honest. They are SIG lines I grabbed from a LHS in Kansas so I could fly. I crimped the ends on and flew them. When Dan sends me the proper set I will be using those exclusively.

Tip high level and inverted. That's what I was told. When the Fox is tunes right it flies fine though. Maybe the power compensates. I used 3/4 oz (I think) of tip weight.

No warps in the wing. There was but I fixed it after the first time I flew. The guy I was flying with told me not to go inverted until I fixed it so I did. The coming in happened after about 12 flights.

I will keep the rudder as is for now. Thanks as always Ken.





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Rudder Offset Empty Re: Rudder Offset

Post  pkrankow Wed Apr 10, 2013 10:11 pm

Sounds like you need to stretch those lines out and measure.

http://www.harborfreight.com/1-2-half-inch-x-330-ft-open-reel-measuring-tape-36819.html
worth every penny.

http://www.lowes.com/ProductDisplay?partNumber=70424-273-L1706N&langId=-1&storeId=10151&productId=3400152&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1
or this.

I use it for doing my landscaping, and anything else I need that is longer than my 35 ft tape. I have found it short before, but used some giant nails to stake out my line.

For control line it just makes life easy. Put a nail in your mailbox, or the back corner of the garage and stretch everything out together. You can make new spectra lines easy this way too.

Phil
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Post  Cribbs74 Wed Apr 10, 2013 10:20 pm

Thanks Phil,

I have a 100ft tape measure and 1.5 acres of property so I will see how long they are. What I don't have is extra .027 sized thimbles and crimp sleeves if I have to cut!!!

Ron
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Post  RknRusty Wed Apr 10, 2013 10:36 pm

Do you have a proper crimping tool, or do you make do with some sort of pliers? I've been using a set of really dull large wire cutters, but that's probably not the best idea. You can get most sizes of crimp tubes at a hunting and fishing outfitter store. That's where I get my crimp tubes, as well as plastic coated steel leader wire for leadouts. WalMart doesn't sell stuff for making your own tackle. When I go get a spool of thicker wire for the SS leadouts I'm going to pick up some crimping pliers. I'd feel like a real moron if that was the death of my plane.

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Post  Cribbs74 Wed Apr 10, 2013 11:06 pm

I use a pair of wire strippers that have a crimp cutout. I will check the fishing section at Bass Pro sometime.

Ron
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Post  pkrankow Thu Apr 11, 2013 7:15 am

With wire you can wrap and solder quite easily. Use some copper bell wire and wrap a layer over the wire, then fold the tag end back and wrap that in the second layer. Finally paste flux and solder. Takes longer than a crimp connection though.

You can also tie the wire wrap ends together and use heat shrink tube instead of solder.

Phil
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Post  Cribbs74 Thu Apr 11, 2013 2:30 pm

pkrankow wrote:With wire you can wrap and solder quite easily. Use some copper bell wire and wrap a layer over the wire, then fold the tag end back and wrap that in the second layer. Finally paste flux and solder. Takes longer than a crimp connection though.

You can also tie the wire wrap ends together and use heat shrink tube instead of solder.

Phil

I just may do that Phil. Measured my lines.......61' eyelet to eyelet. Rolling Eyes
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Rudder Offset Empty Re: Rudder Offset

Post  Ken Cook Thu Apr 11, 2013 5:14 pm

Soldering your terminations is a unacceptable method as it will provide quick failure of the line end. One very important aspect is to not create a hard point. Soldering your termination will do just that. Many of the crimp tubes like the style that Sig uses is aluminum . Solder and aluminum are incompatible. The other problem you create is that the flux gets into the windings of the cable which will inherently cause the line to corrode and it's next to impossible to remove it completely.

Line ends that are wrapped with fine copper wire act as a moving joint which doesn't cause a stress riser in the lines. While crimp tubes are widely accepted, they can also be a source of termination end failure. You just can't see inside the crimp tube as to whether or not your damaging the cable during the swaging process. Crimpt tubes can also provide a hard point at the line end and one can remedy this by using the proper shrink tubing approx 1" long adhering onto the crimp sleeve and back onto the lines. This stops the flexing right at the tube. Chamfering the inside of the crimp tube is also a good practice prior to swaging. Soldering once was an accepted way to secure but that has changed a long time ago due to the above. AMA clearly defines the proper termination practices. Understanding many don't belong to AMA the correct methods or guidelines have been created by them to insure that failures are limited. In my honest opinion, even though one may have had success doing it in the past it's not recommended. MBS model supply can provide you with the eyelets and crimp tubes for a very low cost. The .015" cable should pass through the crimp tube 3 times.
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Post  ebeneezer Mon Apr 15, 2013 2:21 am

Hi guys, this has been an eye opening and instructional thread. I just thought. if some offset is is good, more must be better.
There's a lot more to controline flying than I thought. I think I better join a dedicated club to get the most out of it. I'm getting bitten by the 1/2A controline bug.

Cheers Rudder Offset 3918962684 Rudder Offset 4201307885
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Post  ian1954 Mon Apr 15, 2013 5:53 am

Rudder Offset Cl_eye10

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Post  jhaye Thu Apr 18, 2013 4:53 pm

Hey Ron,

3/4's of and oz. is not much, I have 1.5 ozs. of tip weight in my Ring. My buddy the 40 year old veteran thats been helping me trim my plane has had me add weight twice to get where were at with it. The last time was only 1/4 of an oz. It will make a huge difference on line tension. Just a thought, I think you might be a smidge light on the tip weight. Also if you want a good tutorial on how to properly terminate line ends the AMA approved way go to the Tulsa Gluedobber's website (the control line club of course) and they have a great tutorial on making lines the correct way.

Jim Hayes
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Post  pkrankow Thu Apr 18, 2013 6:10 pm

and some days I cut rudders off because I did the repair wrong...

I had about 3/4 inch offset in my Super Ringmaster. I noticed that I glued the crack in the tail crooked. When I clamped it and glued against a table it now has 3/8 inch offset.

Phil
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