## Moments & couples 2D (for now)

Hey guys and girls, im new to this forum but been looking at it for a while, its a great read and always a challenge here or there, but for now i was hoping to get a little help

:)
1. The problem statement, all variables and given/known data

The direction of the two thrust vectors of an experimental aircraft can be independently changed from the conventional forward direction within limits. For the thrust configuration shown, determine the equivalent forces-couple system at point O. then replace this force-couple system by a single force and specify the point on the x-axis through which the line of action of this resultant passes. These results are vital to assessing the design performance.

2. Relevant equations

any help would be really really helpful cheers!!
 of the middle of the plane is Point O giving me a moment i can rotate on lol now i can get somewhere :)
 Recognitions: Homework Help Science Advisor I hope you are getting it, because as you say, the diagram is not too clear.

## Moments & couples 2D (for now)

yeah i have got a much better diagram now

should find Mx but yeah im really not too sure how to go about it
 Recognitions: Gold Member Homework Help Science Advisor As noted, your image wasn't too clear, and now I don't see it at all. It appears though that you should find the resultant of the 2 thrust force vectors (magnitude and direction), and the torque of those 2 vectors about point O (break the lower thrust vector into components for simplicity in calculating its torque), then place that resultant force and couple at O. To find the equivalent force through the x axis, I'd divide the couple by the y component of the resultant force.
 yeah thats what i have been attempting, ill give it another good shot when i get home :) thanks :)
 im not to sure what i can do with that angle of thrust at 15degrees
 Attached Thumbnails
 mm i think i have gone down the wrong road with this question should i be looking at it as a torsional question? that might make life easier
 bump?
 Recognitions: Gold Member Homework Help Science Advisor Nice pic. As I mentioned earlier, the resultant force is the sum of the 2 thrust vectors, and the resultant moment about O (couple, or torque, if you wish), is the sum of the moments of those vectors about O. Try breaking each vector into its x and y components. The upper force has an x component only. The lower one has an x component of Tcos15 and a y component of T sin 15. Sum torques of those componnents about O, watch plus and minus signs. Show your work so that we may be of further assistance. Your result will be a function of T, which is not given.
 is the answer 2.69T Mo = 0: T3+tsin15x10 - Tcos15x3

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 Quote by random101 is the answer 2.69T Mo = 0: T3+tsin15x10 - Tcos15x3
EDIT: Oops sorry! You're right. I was wrong. I'm still confused by the Mo=0.

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