Posted by Maxthrottle |
Jan 03, 2012 @ 05:12 PM | 3,056 Views
Again in reference to jets and their sensitive nature especially with Tailerons or Stabilators, the servo linkage needs precision setups no different than found on precision fliers.
Many argue TX resolutions but this not only needs a precision servo but also proper linkage setup.
e.g. Deflect the surface to its maximum range. The control horn of the surface should still clear the pivot point or where the fixed surface is connected to the moving surface. From the horn you then want to connect the link rod to the inner most hole of the servo arm that will swing the servo through its full movement.
The advantage is you get the maximum mechanical advantage with the highest torque from the servo making even a light servo strong.
A quote from Troy Newman
Geometry of Pattern Plane Linkage
Geometry is a huge part of linkage setup. We're now dealing with precision setups not 3D. We're talking about using the servo to its maximum efficiency and using the best mechanical advantage possible on our linkages.
First step: You want to choose surface control horns and servo arms that give you only as much throw as you need. If you're only going to fly on 10 degs of aileron travel why set up the linkage for 20 degrees maximum? I never run my flying rates less than about 80%. Yes that means D/R values are around 80% this gives me some wiggle room to get a little more aileron travel, if needed, but still maintain the resolution of my servos. You want to run the longest control horn...Continue Reading
Posted by Maxthrottle |
Jan 03, 2012 @ 04:40 PM | 2,837 Views
I've found for many jet configurations from manufacturers to be off particularly for jets and their flight envelope that differs from standard prop jobs. So here's a quote directly from a JR manual.
Source JR TX manual on Flight modes, D/R and Expo.
For example, let’s consider a jet aircraft and how Flight
Modes might be used to make the pilot’s job easier. The
jet will utilize 3 Flight Modes - 1 for takeoffs, 1 for flying
at high speed and 1 for landing.
During takeoff, full control deflections are desired, with a
moderate amount of Exponential to assist in rotation and
control of the aircraft at takeoff speed. Steering should
have a lot of Exponential to avoid over-steering during
the takeoff roll. So for the 1st Flight Mode (FM0), Dual
Rates and Exponential curves are set for Ailerons and
Elevator to allow adequate control for rotation and control
at takeoff speed, while a high percentage of Exponential
is set for the rudder/steering to help prevent over-steering
during take off. If the aircraft is equipped with 3 position
Flaps (Retracted, Take-off position and Landing position),
the Take-off flap position can be assigned to only the 1st
Flight Mode to assist in takeoff. There may also be a Gyro
attached to the steering/rudder and the Gyro gain can be
turned-on and associated with the Take-Off Flight Mode
to assist in keeping the aircraft straight during the takeoff
For normal flight at higher speeds, the 2nd Flight Mode
(FM1) would be...Continue Reading