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Building Tips and technical articles. => Building techniques => Topic started by: Steve Hines on September 14, 2010, 07:03:07 PM
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should I put offset in the rudder like the plans say, or like the Flite Streak I just got done with, that Bret said to leave it out. It flys great. Is offset something thats just not done anymore. Thanks Steve
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Rudder offset is not needed if there is sufficient line rake (3 to 6 degrees). A bit of engine offset is not a bad idea (1 degree) or just enough to assure there is no inset. Build straight, check and double check. hope this helps.
Bob
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One of the experts commented that he uses just enough rudder and engine offset to be sure that there is no "inset". I have a new Twister that was giving me fits and on closer inspection it seemed to have a very small amount of left rudder. I tried to make it straight but failed.
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You could try just adding a tab for starters. use some hard plastic. Thin enough to hold an angle when bent and a small bit of clear plastic tape to hold it to your present rudder.
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Thanks I will give it a try
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The Akromaster was my first plane bigger than a 1/2A model, way, waaay back. It's a great little airplane. I went through two of them using the same 'ol Fox .19 on the first one until is was no longer rebuildable, then built another one and wore it out too. The Akromaster(s) were all I flew for about three summers, lots of good memories with 'em. I can't begin to guess how much fuel went through that old .19.
I'd recommend just building yours with little or no engine offset. Place the leadouts as shown on the plans. Then finish it with the rudder fixed at about 1/4" offset measured at it's trailing edge, but no more than that. Just take your time during your construction, you will learn that in most cases trim tabs are for those who don't build straight. y1 ;D
Have fun!
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I'd recommend building in all the adjustable stuff you can...leadouts, rudder, control ratios, etc. That way, you can adjust one thing at a time and learn a lot more from that one model. The latest discovery for me was that since the lines would go slightly slack during a few of overhead maneuvers, that a wee bit of right thrust in the engine would make them tighten up quicker. I knew this from my teens...on combat models, but had not tried it on a stunter. A little bit is a good thing. The leadouts will then be slightly forward, to return the plane to tangency.
Basic rule is that you want the model flying tangent to the circle, so it is not draggier than needed. That leaves more thrust for accelerating the model back to cruising speed, and speed = line tension. Lack of line tension causes, uh, you know...crashes. Maybe even most of them. Get your model trimmed before you push it too hard! You should not have to compensate (handle wiggling, whipping, etc.) for your model. Trim the model! That includes: line size, type, and length, handle adjustments, propeller brand, and size, fuel tank height, muffler pressure or no, nitro content, etc. It all matters. The better it flies, the better you fly, and the longer it will last! y1 Steve
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Hi Steve Hines (just as to differentiate between Hines and Helmick! LOL!!),
The accepted practice is to not use rudder offset, but be real sure the rudder is not *inset*. A small amount will be ok on an Akromaster, but just enough to make sure it isn't turned in. In the past (long, long ago in a Galaxie far, far away....) a good bit of rudder AND engine offset was thought to really help line tension. All the OTS and Classic era planes I have seen used both, originally. It can help line tension (I guess) in level flight, but things can really go bad during maneuvers, and up top, if very much is used since excessive yaw will be encountered and line tension is lost due to the model slowing down too much. This is really evident when too much offset is used on the overhead maneuvers.
I will still add just a touch of engine offset, since it is easy (for me) to build it in the wrong way, it seems! I flew my Tomahawk with the OS 20FP (BBTU) the first time and after several flights my son measured the prop on both sides and it had about 1* inset. I had flown three or four patterns with it and it just felt slightly light on the lines, but I always had control. I put one washer under the front of the engine and haven't messed with that part again.
Mongo