Tapio
My models fly with CG at 80 - 85% but the optimum position will depend on tailplane area, wing area and tailplane location relative to the wing. I suggest you proceed on the lines I've given and compare with other published information to confirm your judgement. If you change the design, reexamine model stability.
Bob
----- Original Message -----
From: Tapio Linkosalo
To: Indoor_Construction_at_yahoogroups.com
Sent: Friday, December 14, 2007 7:12 AM
Subject: Re: [Indoor_Construction] Re: F1D CG poll
The wing flies at some positive incidence to the incoming airflow. Thus,
if wing is rigged at 0 degrees relative to the fuselage, also the latter
flies at the same positive incidence, and the motor thrust is not parallel
to the flow, but upwards. Now, if the wing incidence is about 5 degrees,
only less than 0.5% of the thrust is _not_ parallel to the flight path. I
do not think that makes any difference. I do not think that the fuselage
would produce any usefula mount of lift, either, it has extremely poor
aerodynamic properties to that (very low aspect ratio), and I think the
drag produced by angled fuselage overcomes the lift by a large margin.
Why is it then good to fly with a drooping tail? My guess is that the
banefit comes from larger vertical separation of tailplane and wing. With
zero incidence in the wing, the plane flys tail low, which will put the
tailplane lower relative to the wing, and most of all, away from
thedownwash caused by the wing. Thus the tailplane operates in a "cleaner"
air, in a more efficient manner. And probably also with lower drag, as the
airflow is less turbulent.
But now, are there no comments on the CG location? Is this classified
information?
-tapio-
[Non-text portions of this message have been removed]
Received on Sat Dec 15 2007 - 03:27:40 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:45 CET