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Building Tips and technical articles. => Building techniques => Topic started by: Gary Anderson on October 19, 2007, 01:07:50 PM
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Hi guys, I was looking at the Magnum Kit Manual and noticed that it shows the flaps and the elevator at a 45 degree deflection. Does this mean it is a one to one ratio? The control horn hook up, doesn't seem to be that ratio. To old to go back to school, just looks like it isn't a one to one ratio. Would appreciate any input, thank you Gary
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Gary,
45°-45° was popular for a long time. It may have been the intended proportions. Have a Magnum manual around here somewhere... Don't worry about the 45° angles shown - you'll never get them that far. It IS a good idea to make the controls free and equal past where you'll ever need to go. It won't bind up on you, that way.
Quick check: The flap and elevator control horns should show on the plans side-view. If the radius from hinge to pushrod hole is the same at the flap horn and elevator horn, the flap and elevator angles are the same. I'm talking about the rear pushrod, not the one from bellcrank to flap.
Magnums flew well, and far as I know, most were built per kit instructions, unless the builder had some special ideas.
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Hi guys, I was looking at the Magnum Kit Manual and noticed that it shows the flaps and the elevator at a 45 degree deflection. Does this mean it is a one to one ratio? The control horn hook up, doesn't seem to be that ratio. To old to go back to school, just looks like it isn't a one to one ratio. Would appreciate any input, thank you Gary
Gary,
That is the old school way of doing it and yes it is 1 to 1 ratio. 45° deflection is too much. Should be more like 30° but the most important part is how fast (or slow) the controls are. Best method is to use a 4" bellcrank and at least a 1-1/4" flap horn with an adjustable (slider) elevator horn. The 1 to 1 control ratio is best for models that weigh more than 58 ounces or so. If lighter than 58 ounces, there is a substantial increase in the turn rate by increasing the elevator throw.
Later,
Mike Pratt
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Gary,
That is the old school way of doing it and yes it is 1 to 1 ratio. 45° deflection is too much. Should be more like 30° but the most important part is how fast (or slow) the controls are. Best method is to use a 4" bellcrank and at least a 1-1/4" flap horn with an adjustable (slider) elevator horn. The 1 to 1 control ratio is best for models that weigh more than 58 ounces or so. If lighter than 58 ounces, there is a substantial increase in the turn rate by increasing the elevator throw.
Later,
Mike Pratt
Thank you Mike, I appreciate your input and I'll stop the four inch bellcrank before in gets to a critical point. The most I got out of my other magnum was around 33 degrees and she flew great, Gary