# How would you determine the Lift(thrust) force of a Helicopter in hover

• fujifilm6502002
In summary, you can measure the lift force by weighting the helicopter and measuring the change in pressure.

#### fujifilm6502002

I know the lift force equation is .5*rho*V^2*Area*Coefficient. But I was wondering in the real world how would you measure the lift force? I hope they don't just plug the values for the equations.

The easiest way is to weigh the helicopter. If it's hovering, the lift force equals the weight.

I was wondering like if you are building your own helicopter what would someone use to test the amount of thrust produced by the rotor?

i wonder if bernouilli's equation can be put to use in this case. i know that it can be used when there is wind driving a wind turbine. it should work here

I guess you can use Bernoulli to calculate the change in pressure helicopter.

i think u can find the maximum power yield by zeroing the velocity at the exit

yeah we can find the maximum power yield by zeroing the velocity at the exit

if smbody interested , i caN upload a book on the aerodynamic of the helicopter.
tel me if interested
regards

That would be great.
Thanks

I will try tmrow , i willl send u a link on rapidshare or mhid.net;
ur welcome and hope that will be helpful

definitely interested in that:)

fujifilm6502002 said:
I was wondering like if you are building your own helicopter what would someone use to test the amount of thrust produced by the rotor?
You could do this simply with a spring scale and something to constrain the rotor group to the scale and something to drive it. It is even easier if you have a strain gauge based force transducer because then there would be no axial movement due to the thrust.

In regards to the original question, the airfoils and rotors are well known throughout the flight envelope from wind tunnel testing. The calculations involve effects of trailing blades, etc... Of course, the calculations are always compared to actual testing.

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fujifilm6502002 said:
I was wondering like if you are building your own helicopter what would someone use to test the amount of thrust produced by the rotor?
To test it, you mount it on a test rig and measure the forces.

scale down models and wind tunnels are to measure the force.

this si the link uploaded in the rapidshare

Hope that it is helpful

#### Attachments

• Seddon_J._-_Basic_Helicopter_Aerodynamics__BSP_Prof._Books_1990_.pdf
4.9 KB · Views: 483
another book

#### Attachments

• US_Navy_-_Introduction_to_Helicopter_Aerodynamics_Workbook_CNATRA_P-401__US_Navy_2000_.pdf
4.9 KB · Views: 365
http://rapidshare.de/files/22495932/US_Navy_-_Introduction_to_Helicopter_Aerodynamics_Workbook_CNATRA_P-401__US_Navy_2000_.pdf

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http://rapidshare.de/files/22495355/Seddon_J._-_Basic_Helicopter_Aerodynamics__BSP_Prof._Books_1990_.pdf

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Thanks a lot

heyy there can u pls re-upload the file for me pls? i couldn't download the file. actually I am new here. so pls help to guide me :) thanks in advance eh

hazhand said:
actually I am new here. so pls help to guide me :)

Look at the dates on the posts. This thread has been dead for more than 4 years. It's not surprising the links don't work any more.

Oh. Thanks a bunch ;-) what a shame. Haishhhh now i hardly find the info.

## 1. What is the lift force of a helicopter in hover?

The lift force of a helicopter in hover refers to the vertical force that is generated by the rotor blades. This force is responsible for keeping the helicopter airborne and counteracting the force of gravity.

## 2. How is the lift force of a helicopter in hover determined?

The lift force of a helicopter in hover can be determined by calculating the amount of air that is being moved by the rotor blades and the force it produces. This is known as the lift equation and takes into account factors such as the air density, rotor blade area, and blade pitch.

## 3. What instruments are used to measure the lift force of a helicopter in hover?

In order to accurately measure the lift force of a helicopter in hover, instruments such as a dynamometer, a load cell, and a force sensor are commonly used. These instruments are capable of measuring the force produced by the rotor blades in real time.

## 4. How does the lift force of a helicopter in hover vary with different rotor blade designs?

The lift force of a helicopter in hover can vary depending on the design of the rotor blades. Factors such as the shape, size, and angle of the blades can affect the amount of lift force they can generate. Generally, larger and more angled blades can produce more lift force.

## 5. Are there any external factors that can affect the lift force of a helicopter in hover?

Yes, there are external factors that can affect the lift force of a helicopter in hover. These include changes in air density due to altitude, temperature, and humidity, as well as wind speed and direction. These factors can impact the performance of the rotor blades and ultimately affect the lift force of the helicopter.