Control Wheel Movement

This video reminded me of flying the Boeing 247. It took a lot of wheel but the response was very slow. I got the feeling that the airplane didn't like being disturbed from a stabile locked in course and it took a lot of urging to get it off its track. The Douglas DC-8 was a cable airplane ,too. I couldn't believe it when I saw the flight engineer's panel. All the levers were cable connected and there were lots of cables going through his control stand. Then the 727, with full hydraulic power to everything, was very quick and had very fast roll response, faster than a P-51.

 

I think my arms move less riding motocross.....

I'm surprised they don't get arm pump..

 

The flight controls on the 8,9,and I'm pretty sure the MD80 are cables to hydraulic actuators.

Bob

 

I remember when the spoilers were up in the 727 the roll rate was intensified. You had to be really smooth. But then you almost never used the speed brakes in flight because it sank like a brick at idle.

 

Not on the 9/MD80 at least. It is strange when you taxi behind one in gusty winds, the elevators move up and down independent of each other while at taxi speed. It looks like something is seriously wrong.

This video sort of shows what I'm talking about. Notice one elevator is all the way up and the other just slightly. On the take-off roll they fair as the airspeed increases

https://www.youtube.com/watch?v=UhDsNbUmby8

 

From Boeing:
General
Primary flight controls consist of aileron, rudder, and elevator control systems.
Secondary flight controls consist of lift augmenting leading edge slats, flight and
ground spoilers, inboard and outboard flaps, and the horizontal stabilizer. Warning
systems are provided for stall and adverse takeoff, slats, and maximum speed
conditions.
Lateral Control (Ailerons)
Control column wheels are used for lateral control.
Control wheels are cable-connected to an aileron control tab, and linked together
by a torque tube arrangement that causes both control wheels to move together.
Should any part of the system between the torque tube and the control tab become
jammed, either wheel can drive the unjammed aileron tab cable system with
application of approximately 50 pounds of pressure at wheel rim.
Aerodynamic forces on the control tabs move the ailerons. The ailerons are
cable-connected in a manner that each aileron must respond to movement of the
opposite aileron. Each aileron contains a trim tab that is cable-connected to the
pedestal trim knob. Aileron lateral control is augmented by flight spoilers
operating in proportion to control wheel displacement and/or speed brake input.
Longitudinal Control (Elevators)
The longitudinal control system is a pair of elevators attached to the horizontal
stabilizer. Elevator control is, for all normal flying, an aerodynamic boost system
that operates a single control tab on each elevator. Each control tab is driven by an
independent two-way cable system from the corresponding control column in the
cockpit. The only interconnection between the two control systems is a bus torque
tube that connects the control columns. Movement of the control column moves
the control tab, and aerodynamic force generated by the tab moves the elevator.
As each elevator moves, an additional tab, geared to elevator movement, moves
to assist the control tab. An anti-float tab, geared to horizontal stabilizer
movement, is installed on each elevator outboard of the geared tab to improve
longitudinal trim in a forward center-of-gravity (beyond ten degrees airplane nose
up) landing configuration.
Engine strakes on the engine nacelles enhance longitudinal control for post stall
recovery.

 

This pertains to MD 80, -90 doesn't it? Maybe I missed previous statements.

 

Lou, Bob- That video reminds me of flying formation, where you put in a control or throttle input and then immediately take half of it out nearly continuously to maintain position.

 

Some racers drive like that.

 

Yes.

 

My old friend, Jack leffler flew 727's for a while and was very careful about the roll rate of the airplane and he said that when he was giving landings to a copilot he always placed his hands on his knees, palms up, just below the wheel to make certain that he could catch it if the copilot over controlled it near the ground.