Angier,
Benefits of concave:
1. Potentail for more pressure recovery = less drag
2. Airflow on the upper and lower surfaces at the trailing edge is closer to parallel when they meet = less drag
Drawbacks of concave:
1. Easier to get flow separation = more drag (similar to separation bubble that can form on the the lower concave surface of laminar airfoil sections)
2. Earlier seperation with control surface deflection = more drag (generally only a concern if it occurs due to trimming in a cruise condition)
In the big picture, ensuring the flow remains attached transitioning from the stabilizer to the control surface is much more critical.
FWIW, I have the MKII tail. My surfaces were nearly flat after assembly, perhaps off by ~1 mm. I finished them flat with micro.
Chris Zavatson
N91CZ
360std
From: "Greenbacks, UnLtd." <N4ZQ@VERIZON.NET>
To: lml@lancaironline.net
Sent: Tue, March 29, 2011 7:14:58 AM
Subject: [LML] Re: Finishing Elevator Question
According to Stan, the Legacy manual specifies a concave shape for the elevator surface. The 320/360 calls for straight.
For those of us who may be aerodynamically challenged, what is the benefit of one shape vs the other? Are all the Legacy control surfaces concave? What about the IV and Evolution?
Angier Ames
N4ZQ
ps..had to perform a much needed upgrade to my cockpit yesterday, an accessory power source for my iPad!
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