Exactly. Depends on the airfoil in question.
Got the books.
Can download said profiles for free to anyone who is interested. Do a search for Selig and Illinois Urbana champagne university and you will find his site with the ability to download the data files. In zip form by the way.
As to a5BY why on stunt you can get away with it. Even in a stall you are generating lift. It does not matter in a control line if one wing tip stalls as centrifugal force from the line holds the model in the air and therefore you can tip stall all you want. Likewise said models are so overpowered it does not matter if you are flying in a 100% stall all the time. In fact for stunt you want the tip to stall quite often as it will make a snappier performer.
Last time I was at control line combat, no one was using a wing such as you guys describe. Everyone was using constant taper, constant airfoil properties.
Thanks for the informative post Speedy. It really helps further the discussion. PS. wing loading has nothing to do with a stall, just means you can get out of said stall very quickly and easily.
ORIGINAL: alasdair
It can also go against you.
When a wing section has more percentage thickness, or more percentage camber (or both) then its critical Reynolds Number increases. By that I mean the Reynolds Number (Re) below which the section has a big jump in drag coefficient and sometimes an early stall.
Check out various sections in Selig's books of wind tunnel tests and you will see what I mean. He tests at a range of Re, and you will clearly see the effect of reducing Re.
I have tried to attach a scan of Selig's test of the Eppler 374 section, from which you can see that changing Re from 300k to 200k makes little difference, but consider what happens if the root section re is 200k and the tip is 100k or 60k. Buy Selig's books (Soartech Publications), well worth while.
It is often best on models to reduce the section's thickness and camber when Reynolds Number is reduced.
On a tapered wing, the tip is obviously operating at a lower Re than the root, so this idea of keeping the top to bottom measurement the same while reducing chord will work SOME of the time, but at other times is asking for trouble. You need to check the performance of the section at the reduced Re (and who among you bothers?) or you could have problems.