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Mar 04, 2012, 09:32 PM
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steps: the beginning


credit where it's due. who began using steps on model airplanes? i see that there are many users that call them 'kline fogleman airfoils' and credit Dick Kline with their invention ( see thread https://www.rcgroups.com/forums/show....php?t=1117276 ). still i remember seeing them on model airplanes long before. their more recent use and popularity is due to the tests that tony65x55 did with a flying wing based on the zagnut wing. his thread is here:https://www.rcgroups.com/forums/showthread.php?t=558321 and was started on august 2006. there are some posts in that blog that are worth reading: 1,5,27,29,79,83 and 84. he stresses the point that the step creates lots of drag. after Tony's introduction of the step to successful flight on small models, came the snowball effect and many (including me) have been building models with the step in several configurations.
but the 1st use of the step on models that i ever saw, was on a small model airplane that flew remarkably well using a step, although at the time it was not called so. it was the Dakota, a bipe designed by Joe Wagner, and kitted by Veco in 1949. see plans here: https://www.rcgroups.com/forums/show...a#post15506144 post 123. the step is a big 1, at the bottom. of course, where the step started was with paper planes long before. in 1939, when i began using it, was with paper planes that my uncle taught me to make with a fold (step) when i was 5, and this means that by then it was common knowledge to make paper planes with a step (fold) and has been used for who knows how long, and so the name of the guy who developed it is lost. by 1967 there was so much interest that there was published a book about paper planes, called 'the great international paper airplane book', (copyright in 1967)-of which i have a copy-that shows the step on some of them.
but the 1st use for models, as far as i know, was with the Dakota.
now, if someone knows of something done before, and can substantiate it, i will be happy to add it here.
but i forgot to mention that the reason why i use it is because adds stability-a lot!(in spite of adding drag)-just in case you wonder.
Last edited by phil alvirez; Apr 04, 2012 at 06:11 PM.
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Mar 09, 2012, 01:14 AM
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the Dakota "step"


What you are calling a step appears to be just a way of strengthening the leading edge. The wing still has a definite airfoil, if the bottom is covered it would appear to be flat, however in the balsa kit it seems that the ribs remained exposed, creating some undercamber. The step is also at around 25% of chord, most of the KFm steps are at 40-50% of chord with a flat bottom. Other than strengthening the leading edge, I don't think the step was intended as part of the airfoil design.

DaveL
Mar 09, 2012, 06:29 AM
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a step is a step


Quote:
Originally Posted by Crash&Bounce
What you are calling a step appears to be just a way of strengthening the leading edge. The wing still has a definite airfoil, if the bottom is covered it would appear to be flat, however in the balsa kit it seems that the ribs remained exposed, creating some undercamber. The step is also at around 25% of chord, most of the KFm steps are at 40-50% of chord with a flat bottom. Other than strengthening the leading edge, I don't think the step was intended as part of the airfoil design.

DaveL
a step is a sudden change in the airfoil shape. like a step in a stairways. that's why it is called a step. and a step is a device intended to alter the performance of an airfoil. it is not an airfoil. it's like flaps, slats, slots, turbulators. if the designer of the dak did it with the intention of strenghtening we don't know, but the results show that it changes the performance. some covered the under surface and the plane was very unstable; then removed the covering and it flew fine, that proves that steps improve stability. that i know, for i have added it to some of my planes and they are more stable. and the results of placing steps at certain % still have to be evaluated. i have used them at several % and all do about the same: they improve stability. also placing them on top or bottom improves stability.
Last edited by phil alvirez; Mar 09, 2012 at 06:39 AM.


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