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HeliTorque :: View topic - Lift = weight?
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HeliTorque Forum Index » Flight Dynamics

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Lift = weight?
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Ascend_Charlie
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PostPosted: Fri Mar 05, 2010 3:34 am    Post subject: Lift = weight? Reply with quote

Here's a couple of questions for you aerodynamics whizzes.

1. In a steady climb, the vertical component of Total Rotor Thrust is:
a. greater than the vertical components of weight plus drag
b. equal to the components
c. less than the components

2. In a steady descent, the vertical component of Total Rotor Thrust is:
a. greater than the vertical components of weight plus drag
b. equal to the components
c. less than the components

On what occasions is drag helping to oppose the weight?

Discuss.
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LoachBoy
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PostPosted: Fri Mar 05, 2010 11:48 am    Post subject: Reply with quote

Blimey...... got to dredge my brain (what's left of it) back to my theory exams last year.......

1. = "Equals" - the rate is steady, i.e. not accelerating therefore forces are balanced?

2. As above...... I think.

(Unless I've mis-read the questions).

Can weight oppose drag if they act at right-angles to one another? Good questions and I shall now shut-up before I expose any more of my inadequacies!!! Embarassed
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paddywak
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PostPosted: Mon Mar 22, 2010 9:13 pm    Post subject: Reply with quote

Yep, I think youre right

When decending the induced flow is reduced because of the resultant airflow so the inflow angles decrease and the angle of attack increases, so the total rotor thrust increases.
Looking back in the books it says that there is a point where the helicopter comes into a state of eqilibrium and the TRT= gross weight and the rate of descent will stabilize at a given value of ...x...ft per min.
TRT and gross weight are equal and opposite but the power in use is less than the power required to sustain a hover at a given altitude so further descent is inevitable.

scratch
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