AviationBanter - View Single Post - Tandem-wing Airplanes

**Bertie the Bunyip[_25_]** · February 4th 08, 02:12 AM posted to rec.aviation.piloting,rec.aviation.student

wrote in news:f886c681-9425-48a9-831d-
:

Here are two conflicting statements you made:

They arent conflicting. They're the same statement made two different ways.

In a conventional tailed aircraft, the tail may
have a downforce, no force at all, or an upforce, depending upon the
design of the aircraft, the relationship of the aerodynamic center to
the CG, and the flight regime. There is no intrinsic reason why a
lifting tail (or a tail that in a given situation is producing no
lift) would cause the aircraft to do what you state.

The pitch stability of an aircraft is not determined by
whether or not the tail lifts - it's determined by the relative
position of the aerodynamic center and the CG (CG always ahead of AC),
and the relative angles of the front and rear wings.

I was talking about airplanes that appear conventional, like
the lightplanes we have now. With a lifting tail the CG must be behind
the AC, not ahead of it, and stability would be negative.

Nope, because th estab is part of the AC and the stab on a lifting stab
arrangement is significantly larger thna it's conventional counterpart.

Bertie