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Old 12-18-2003, 02:06 PM
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tiggerinmk
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Join Date: Dec 2002
Location: Milton Keynes, UNITED KINGDOM
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Default RE: Tricycle gear question.

1. The nose gear is usually mounted straight onto the firewall. As the firewall usually has some downthrust built in, the nose gear end up being raked back slightly. Also, the coil spring should face to the rear as that is the direction that the spring is designed to flex. It shouldn't matter if the nose gear is straight down just as long as it's not raked forward. The backward rake helps the plane ride over bumps on the ground.

An example: push the tip of your finger along the table / desk top angled forward. Then put an obstruction in front of it such as a coffee stirrer or paper clip. What happens when your finger hits the obstruction? Now do the same thing dragging your finger along raked backward...

2.
Plane level: This should give the plane a neutral attitude and will take off readily with a little up elevator when you reach flying speed.

Nose down: This will reduce the incedence of the wing in relation to the ground and may actually keep the plane on the ground during the take off run. This may also make it more difficult to 'rotate' the plane for a smooth take off. It will also reduce the prop to ground clearance.

Nose High: This will increase the wing incedence and may cause the plane to try and take off before it has gained sufficient speed. This also means that the nose wheel will be lower than the mains when you are attempting to land. You will have to land in a nose high atttitude to prevent the nose gear from hitting first. You do not want the nose gear to strike the ground first when landing.


Correction: The incedence of the wing should be measure in relation to the oncoming airflow. If the wing is set at 2 deg positive incedence, then the wing will start to generate lift near flying speed. With the plane set level you'll see it 'get light' and more bouncy (if you are on grass). If the nose gear is set nose down so that the wing has a negative incedence is relation to the oncoming airflow, this will make it more difficult to lift off. You may see it suggested that the plane is set slightly nose down, but keep an eye on the wing incedence.