The next day, some dude by the name of "LaPook" asks whether anyone knows whether, in fact, the L10E had a locking tail wheel.
Hey, that LaPook guy seems pretty sharp, he wrote:
"Date: Tue, 4 Oct 2005 15:56:44
From: Gary LaPook
Subject: Re: Asymmetrical thrust
Let's think this thing through.
Why would one use asymmetric power on takeoff?
Some basic flying discussion is in order. Tail dragger aircraft have the center of gravity located aft of the main wheels so there must be a tail wheel to support the tail of the aircraft. That arrangement was known as "conventional gear" in the past. Now it is much more common to have the main wheels located further aft so the COG is forward of the main wheels and a nose wheel is then needed to keep the airplane in a level attitude Ground loops result from having the COG behind the main wheels. If something causes the plane to start to swerve then the momentum of the COG rotating around the resistance from the wheels will cause the swerve to get more and more extreme and results in a loss of control on the ground. You can try this experiment when at the grocery store. Take a normal shopping cart which has castering wheels in front and fixed wheels in back Push it forward in the normal way and then give it a little turn and let go, the cart will straighten out and go straight ahead. Now turn the cart around and push it backwards and try the same experiment and you will see a ground loop and the cart might spin completely around if you had it going fast enough at the start.
If you look at any aircraft you will notice that there is much more of the aircraft fuselage aft of the main wheels than forward and this was even more pronounced in taildraggers since the main wheels are mounted further forward. Because of this, all airplanes have a weathervaning tendency which means that it will attempt to turn into the wind when in contact with the ground just like a weathervane. This is more pronounced with taildraggers but is still a problem with nosewheel airplanes. In order to keep the nose of the plane aimed down the runway when there is a cross wind you line up on the runway using differential braking to point the nose, taxi a little forward to straighten out the tailwheel, lock it in place, (in aircraft that have such locking capability, does the Electra?) hold rudder away from the wind, hold the stick all of the way back to hold the tailwheel in solid contact with the runway, add full power to accelerate. After you reach a speed where the rudder will give you sufficient directional control to hold the nose straight in spite of the weathervaning tendency you push the stick forward to raise the tail while applying rudder away from the wind to keep the nose going straight. You complete the acceleration to takeoff speed in this attitude and then raise the nose slightly and climb out. In airplanes that can't lock the tailwheel you must use taps of the brake on the downwind side to keep it going straight which delays the takeoff.
Asymmetric thrust will also cause the nose to yaw (swing) just like using the rudder and can be used to steer the plane on the ground. It is quite common to bring up the power on only one side to make a sharp turn while taxiing, it is like rowing a boat with only one oar in the water.
So, back to the question, why would you use asymmetric power on takeoff? The only reason would be to keep the plane from weathervaning into an extremely strong crosswind, a wind too strong to deal with by use of the rudder alone. This would require using full power on the upwind side and something less on the downwind side for less than full power in total which would lengthen the takeoff run which doesn't seem like a good idea. A better way would be to simply hold the tail down until a higher speed is obtained where the rudder would have more authority to maintain directional control.
And another basic question, is there any reason to think that there was an extremely strong crosswind for the takeoff from Hawaii?
Gary LaPook"
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