wrote:
On May 20, 6:39 am, Ed Winchester wrote:
nimbusgb wrote:
On May 20, 2:25 am, "Bob Salvo" wrote:
It seems to me that Mylar may only be necessary on the top of the
stab/elevator, since the top surface is the high pressure side. Has anyone
tried this?
The top side is the low pressure side Bob!
I don't think so, as the tail of just about every airplane or glider has
a download. That's how they achieve stability. So it's backward at the
tail, the top surface is indeed the high-pressure side.

Just to add to this "pressure" discussion, my elevator has a shape
similar to the trailing edge of my wing. The top-side is convex, and
the bottom-side is concave. Wouldn't that be a clue as to where the
high and low pressure areas are? I would think the convex side is the
low-pressure side, which is on top.

It's an airworthiness requirement that the glider will tend to pull out
of a dive. So, typically, the concave side is on the bottom to provide
increasing back pressure on the stick as speed increases (sort of like a
trim tab). In his 1989 article on increasing performance, Peter Masak
talked about reducing drag by filling in this bottom concavity. No
mention of the expected drag savings, but lots of words about flutter
concerns.

--
Eric Greenwell - Washington State, USA
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