View Single Post
  #59  
Old November 1st 08, 05:54 AM posted to rec.aviation.homebuilt
Steve Hix
external usenet poster
 
Posts: 340
Default Lancair Legacy Design Flaw?

In article
,
Alan Baker wrote:

In article ,
Steve Hix wrote:

In article
,
Alan Baker wrote:

In article ,
Steve Hix wrote:

In article
,
Alan Baker wrote:

In article ,
Steve Hix wrote:

In article
,
Alan Baker wrote:

Pusher or puller doesn't affect pitch forces. What affects pitch
forces
is the length of the moment arm between the centre of mass and
the
thrust line.

Or center of drag vs thrust line?

The problem with that is "centre of drag" changes.

And, as it does, so would pitch resultants.

Better to take all the separate moments for the various components
about
the centre of mass.

Which will change as airspeed/AOA/etc. change, right?

No. The centre of mass *never* changes (in the context of this
discussion.

No, mass (other than fuel onboard) doesn't. But drag components can
change with changes in speed, AOA, flap positions, landing gear, cooling
flaps, etc.


Right. So take moments about the thing that doesn't change.


Looks to me that we're in something resembling violent agreement.

The center of mass doesn't change (ignoring fuel burn).

The drag components measured from that center certainly do, however.