Originally posted by lennyk
Can anyone give a layman's explaination of Reynald's number
especially with respect to the relation with bigger planes
flying better than smaller planes of equivalent wing loading.
Thanks,
L
There have been some excellent answers to this already in this thread. However, here's my little bit!...
Reynolds number is the degree of 'stickiness' of a fluid. It becomes important when considering scale factors; hence its pertinence to model aircraft.
Scale factors happen because halving the size of something doesn't result in a halving of the other factors. For instance, halving the size results in a reduction of the weight by 8 (2x2x2). This has effects like, the legs of an elephant are proportionally bigger than a mouse due to the fact that the weight difference is 8 times bigger than the height difference.
This effect happens to surface tension as well, which is why an insect can walk on water, when a man can't.
Air has the same surface tension, density etc etc whether it's passing over a full scale aircraft wing or a model's wing, so the scale factors make it react differently from each other.
The Reynolds number is one of the ratios that can be used to predict this.
There's more info, related to scale factors in aerofoils here:-
http://www.desktopaero.com/appliedae...esections.html
David C.