Side thrust and up/down thrust for pushers

wilerbee · May 16, 2003, 10:08 AM

Hi all,

I am building a Mirage 3 wood kit, it is for a .46 to .61 pusher engine but the plans do not show the amount of side thrust and down thrust. My question is should the the side thrust be left thrust and down thrust be up thrust and how much of it ? Any help on enlightening me will be greatly appreciated.

Willis

cv990 · May 30, 2003, 08:19 AM

The effective direction of rotation of the engine is reversed on a pusher, so the side thrust should be in the opposite direction as usual. You can see this by viewing behind the model - standard rotation is clockwise on a normal model. On the pusher, counter-clockwise as you're now looking at the other end of the engine. So left thrust instead of right.

As for up/down thrust, conventional wisdom usually dictates a thrust line running just above the C.G.'s vertical position to stop excessive climbing when power is applied. By the C.G.'s vertical position I mean the height of the CG above the floor of the Fus/Wing. Low wing planes will have a low vertical C.G. position as there's a lot of weight (the wing) low down - and vice versa for high wing planes. Applying this same theory to pushers - the thrust line (carried forward) should be set to just above the C.G. which will normally mean up thrust (in the aircraft sense).

May 16, 2003, 10:08 AM	#1
wilerbee Registered User Hong Kong Joined Jan 2002 838 Posts	Side thrust and up/down thrust for pushers Hi all, I am building a Mirage 3 wood kit, it is for a .46 to .61 pusher engine but the plans do not show the amount of side thrust and down thrust. My question is should the the side thrust be left thrust and down thrust be up thrust and how much of it ? Any help on enlightening me will be greatly appreciated. Willis

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May 30, 2003, 08:19 AM	#2
cv990 Registered User UK Joined Feb 2003 24 Posts	The effective direction of rotation of the engine is reversed on a pusher, so the side thrust should be in the opposite direction as usual. You can see this by viewing behind the model - standard rotation is clockwise on a normal model. On the pusher, counter-clockwise as you're now looking at the other end of the engine. So left thrust instead of right. As for up/down thrust, conventional wisdom usually dictates a thrust line running just above the C.G.'s vertical position to stop excessive climbing when power is applied. By the C.G.'s vertical position I mean the height of the CG above the floor of the Fus/Wing. Low wing planes will have a low vertical C.G. position as there's a lot of weight (the wing) low down - and vice versa for high wing planes. Applying this same theory to pushers - the thrust line (carried forward) should be set to just above the C.G. which will normally mean up thrust (in the aircraft sense).