Throt/ Rud

[John Pavlick]

Ed,
 Don't think about inverted / upright / right / left like that. It's all the
same to the airplane. Upright the slip stream hits the left side of the fin
causing Left yaw. For sake of argument: Right thrust will be used to
counteract this. Inverted, the SAME THING happens. Don't think right / left
in reference to YOU, think left / right in reference to the AIRPLANE. When
inverted the slip stream hits the left side (still) of the fin - unless the
motor suddenly starts turning the opposite way. Same thrust offset ("Right")
required unless the slip stream goes away in a push. Now if there's right
thrust, you need left rudder to offset the right thrust which is trying to
make the airplane yaw right in the absence of the slip stream air on the
fin. If you still want to think about it the "other" way, remember "left"
rudder when inverted will make the plane yaw to the "right" (in reference to
YOU standing there watching the plane). Now I'm getting confused.
 If you think about what Chip described: Trim for straight flight at full
throttle, mix left at idle. Another way would be trim straight at idle, mix
right at full throttle. That's what I've been doing. Same difference.
John Pavlick
http://www.idseng.com


  -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Edward Skorepa
  Sent: Wednesday, January 26, 2005 8:15 PM
  To: discussion at nsrca.org
  Subject: Re: Throt/ Rud


  I'm confused too. I know, I know I shouldn't argue with someone like chip
but I believe the main reason we're putting right thrust is an asymmetric
vertical fin. On most conventional airplanes the area above thrust line is
much greater then area below. So, the spiraling slip stream  will hit the
top portion of the vertical fin from the left pushing tail to the right thus
right thrust. When inverted, the spiraling slip stream will hit vertical fin
from the right because fin is now on the opposite side and  pushes tail to
the left. To straighten the flight path, we need now the left thrust which
is already there. During inverted push ups, why do we need to use left
rudder? The spiraling slip stream misses completely vertical fin and the
right (left when inverted) thrust is causing airplane to yaw left. If you
have a big gasser, turn on smoke, do inverted push up and watch where the
smoke goes. However, Chip's approach of fixing the inverted push ups problem
is quite interesting and I'll try it on my new bird I'm working on right
now.
  ed
    ----- Original Message -----
    From: Nat Penton
    To: discussion at nsrca.org
    Sent: Wednesday, January 26, 2005 11:32 AM
    Subject: Throt/ Rud


    Cameron Smith relayed comments from Chip ( from RCU ) relating to how he
uses a mix to eliminate the need for right thrust. I know Chip knows but he
left me confused. Could someone clarify what he said?


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