I think there is a certain amount of apples to oranges when comparing thick to thin airfoils. Dont think the WW1 guys would not have wanted a Pitts Special they would have been unstoppable against any of the WW1 planes. When we replicate a scale plane we replicate the problems too taking the out of scale is just turning it into Twilight Zone physics wise. A Cub is about the same size as a N11 which one performs better? The next advancement would be the M-6 which is faster still and does better upside down stuff with a good stall, and then you go symmetrical. The nails dont change size only the person.Ĭlark Y and its competition USA35B( Cub) were the first step away from the WW1 style undercamber which have a very narrow control range the stall is ugly and the top speed is limited on how much down trim you can add. When their body is large they get to distribute their weight over more points. Think of it like one of those guru people who sleep on the nail beds. 1/4, 1/3, 1,2 scale planes get large enough where the numbers start becoming more reasonable. We talk about it in reverse the air tunnel guys build small and dream big we get stuck making big to small. Reynold's Numbers are the conversion factor for air molecules. But what sort of a factor is this in reality? Is it a significant factor on the larger 1/4 and 1/3 scale WWI models which are quickly becoming the norm?Īnd most importantly what other airfoils ofter a good compromise between scale appearance and reasonable performance? In my opinion, the Mick Reeve's WWI models have proven that a completely scale airfoil is a viable option on larger models. A lot is made of the problem caused on "smaller models" by the effects of the Reynold's Number ( ). But most other WWI aircraft had a much thinner airfoil, sometimes razor thin. These generally don't look too bad with a Clark-Y. But just how much easier to build and how much easier to fly? For most WWI aircraft the Clark-Y airfoil is painfully, obviously out of scale, the exception being the "fat" airfoils of the cantilever Fokkers, for example, the DVI, DrI, DVII, and DVIII. In short, using the Clark-Y can make a wing easier for a novice to build and make the model easier for a novice to fly. In addition, the Clark Y section's depth also permits the flush installation of what are considered "standard" sized R/C servo motors within a wing for actuation of ailerons, flaps etc., without an excessive reduction in performance." The depth of the section lends itself to easier wing repair, as the modeller will often then have better access to balsa structural elements. The benign stalling characteristics of the airfoil are another aid, as this allows an inexperienced radio-control model hobbyist a better possibility of recovering from a stall in flight, to the benefit of the model. Young and inexperienced modellers are thus able to build model aircraft which provide a good flight performance due entirely to its aerofoil shape. The Clark Y is appealing thanks to its high camber, which produces a very good lift-to-drag ratio on comparatively lightweight balsa models, and for its near-horizontal lower surface, which aids in the accurate construction of wings on plans mounted on a flat construction board. Application on model aircraft is very wide, ranging from free-flight gliders through to multi-engined radio control scale models. "The Clark Y has found tremendous favour for the construction of model aircraft, thanks to the flight performance that the section offers at medium Reynolds number airflows. Wikipedia has this to say about the prevalence of the Clark-Y airfoil in model airplanes: