Side thrust which way and 'simple' why, quickly before maiden!!!!

[nickf]

Hi,

I have been putting together a mini mustang and built the power pod with the side thrust that gives it a good 'point' to the right, it you were sitting in the cockpit'. I understand that this is to counter the effects of the rotating prop - but in which direction?

My logic would say that a prop swinging CCW (when sitting in the cockpit') would create a wash/airflow that would tend to lift the right wing, pressure the left down and perhaps hit the fin on its RHS, all of which would cause the plane to roll to the left. Therefore you need a right thrust from the motor to induce a slight raw to the right to compensate. Reading around on this I'm even more confused, with claims and counter claims about p-thrust, torque roll and advanced aero dynamics!

But overall it seems that the opposite is true, you need a thrust angle to the right, for a CW rotating prop - can someone explain this simply please so I know what to do

The plane is a Christmas present for my son! So do I need to put together a motor pop with the offset in the other direction?

Many thanks

nick

 

[rockyboy]

There's good write ups on this over here:

https://www.flitetest.com/articles/Thrust_Angle

http://oldsite.electricrcaircraftguy.com/motor-thrust-angles

Usually the CW or CCW designation is based on looking at the front of the plane, not from the in the cockpit point of view. The standard in puller/tractor type RC configurations is CCW - counter clock wise facing the front of the plane, or clock wise if you're in the cockpit.

But when you're buying props, look for CCW, and on small foamies add some right thrust

 

[Geeto67]

BTW, don't let the shape of the prop fool you. Sometimes people look at the straight edge of the prop and think of it as the leading edge, not the trailing edge, and look at the curved edge and think it is trailing when it is leading. This can make someone think the airplane's prop is spinning opposite of what it is doing. The edge of the prop that is furtherest from the nose of the airplane is the leading edge, regardless as to whether it is round or straight.

As for the P factor - the best demonstration I can think of is to get a power drill with a screw bit, a screw and a board. As you screw the screw into the board the drill is going to torques the handle, take note as to the direction the torque the drill is applying to the handle. The same thing applies to airplanes - your prop is a giant diameter screw with one thread, the air is the board, and the airplane is the drill.

 

[nickf]

OK many thanks.

nick

 

[Grifflyer]

Good luck with the maiden!