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General control line discussion => Open Forum => Topic started by: Marty Hammersmith on October 24, 2023, 08:45:16 PM
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I am plans building a Ringmaster S-1. I read a comment in a thread that suggested the engine and rudder offset is not effective on this model. What do you think? Do I build in rudder offset? What about shimming the engine?
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Rudder off set is a 50's myth. It is NOT needed..When it works, it's not needed, when its needed, it does not work..How ever. about 2 degrees of outside engine off set is a good thing just to make sure it is not inset. H^^
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I am plans building a Ringmaster S-1. I read a comment in a thread that suggested the engine and rudder offset is not effective on this model. What do you think? Do I build in rudder offset? What about shimming the engine?
To echo Ty, rudder offset is completely unnecessary, and its actually counterproductive. It causes additional drag which limits speed, and this kills the line tension it is supposed to help create. As to engine offset, since this is easily adjusted with shims, Id suggest flying it with the engine at 0 deg offset. See how it flies like this, then it can be adjusted if needed. But do yourself a favor, if you havent already, and build in an adjustable leadout guide and tip weight box. These are things you will never regret adding.
Gary
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Rudder off set is a 50's myth. It is NOT needed..When it works, it's not needed, when its needed, it does not work..How ever. about 2 degrees of outside engine off set is a good thing just to make sure it is not inset. H^^
With today's power you are absolutely correct but in the 50's we didn't have that much power. I had my first Ringmaster in 1959 and it had plenty of rudder offset. Power was a McCoy 29. I know now that it probably needed tip weight more than it needed rudder offset and the leadouts were all wrong. We have learned a lot since then. Build it straight.
Ken
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I'm glad I asked! I made adjustable leadouts and when I cut out the rudder and vertical stab I just cut that out as one flat piece. I didn't get to the weight box yet.
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I am plans building a Ringmaster S-1. I read a comment in a thread that suggested the engine and rudder offset is not effective on this model. What do you think? Do I build in rudder offset? What about shimming the engine?
Tip weight is THE KING of line tension. The other gimmicks generally work at the wrong time create excess line pull when you don't need it.
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Marty, I have built several S1's, for the most part engine offset is a good thing as Ty said. I have used ~3 deg. Brodak has some machined mounts that set the offset (https://brodak.com/profile-engine-mounting-plate-3.html). Don't know what you are planning for power but if it is an older engine (Fox, McCoy, K&B, OS Max's baffled) add a 1/32" plywood strip between the mount and engine lugs to be a crush pad (these engines don't have machined flat mount lugs), this prevents distorting the case as you tighten it down on hard Aluminum mount pads.
As to the rudder, I like again about 3 degs to keep it from fighting any minor alignment issues.
Best, DennisT
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Marty,
All good information here but if you have come away unsure or mixed you can easily install an adjustable rudder. This can be done using thin brass strips as hinges and a light duty clevis. After arriving at the best prop pitch and diameter for the engine selection and with say 2 degrees engine offset try starting with 0 degrees rudder offset. Strive for good line tension in an overhead eight. Remember too much rudder offset results in the "slipping" and increased drag just slowing the plane down. Most model designs today do not recommend rudder offset.
Steve
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On the old models the offset thing was over done. We have learned that airplanes don't fly as well when flying sideways!! One to two degrees engine offset and make the rudder adjustable but start off straight. All of my rescued Ringmasters have the rudder cut off and glued back on straight. Adjustable lead outs come in handy but one of my best flying Ringmasters has the lead outs in a "stock" position and unless something happens I won't take them out. Adjustments a great, but only make one at a time and fly the model several times before the next change. The hard part is getting to know and recognize what changes are need and why, developing that feel for it. That only comes with practice and lots of flying. Because no matter what change you make to an airplane, you can't tell what it did until you fly it! The airplane can't fly by itself!!
Type at you later,
Dan McEntee
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I am a convert to having no rudder or engine offset on my models. Being somewhat of a rookie builder I originally just followed the plans on my early models and put in the offsets. But my most recent build is a SIG Skyray 35 where I followed the recommendations of many expert builders and eliminated the offsets. But I did install an adjustable lead out guide and adjustable wing tip weight box. The Skyray is probably one of my best flying models to date.
I am also even removing the rudder offset on some of my early models in an effort to have them fly better.
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All great input guys. Thank you!
I vacuum bagged 5.7oz carbon fiber with West 105 epoxy to the fuselage on my flat glass layup panel so I’m satisfied I didn’t build a banana of a fuselage. Its 3/8 balsa core instead of 1/2 inch and no plywood sandwich from the front of the engine mount to a bit past the leading edge of the engine. A 2nd layer of carbon was added instead of plywood. The engine mount rails and landing gear strap hard points of Douglas Fir are inset in the balsa and captured by the carbon. So, as long as I center the vertical fin/rudder I should be neutral. I might bias it slightly just to make sure.
Power is a Blue Bird 28 converted to CL with Delrin venturi. It is 9 oz including an R/C style muffler. Blue Bird is the same engine as the World Engines Brat. I have a fleet of these engines in R/C planes and on the shelf. I haven’t worn one out yet starting in the mid 1990’s. I have the nylon engine mount shims in 1,2 and 3 degrees. I’ll probably start with 1.
How do I make an educated guess about wing weight for the first flight(s).
Let me explain that the carbon, epoxy and ability to vacuum bag this project are all no cost to me. I have all of this on hand from a racing hydroplane I used to drive. The Ringmaster seemed a great place to experiment a little.
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This is how I was taught to set the initial wing tip weight..Set the model so it is resting on the rudder and hold the spinner or prop so the model can tip either way.. Place your line reel, sans handle, in the middle of the inboard wing.. Add weights into the weight box until the out board wing slowly drops to the table. H^^
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Great tip Ty, I gonna try that! I just finished building another S-1 and didn't have it ready in time for the fly a thon.
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Great tip Ty, I gonna try that! I just finished building another S-1 and didn't have it ready in time for the fly a thon.
The main thing is to build a tip weight box or have a system where you can add or remove weight as needed. For a Ringmaster, 3/4 ounce is in the neighborhood, 1 ounce for first flights if you want a safety buffer. Ty's method will het you in the ball park also, just be able to adjust it.
Nice boat!! Bill Seebold used to have a small shop near where I used to live years ago when he was starting out, and if we were driving by at night I always asked whoever was driving to slow down so we could see inside if he had the big door open. I like watching hydroplane racers, especially unlimiteds. I'm not much for riding in them or driving them, though!! I'm sure you have noticed that they don't have brake pedals in them!!
Type at you later,
Dan McEntee
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Lots of good advice!