How they Fly?

Principles of Rotary Flight

helicopter main rotor

The Main Rotor

The lifting force is produced by the rotors.
As they spin they cut into the air and produce lift.
Each blade produces an equal share of the lifting force.

Spinning the rotor against the air causes lift, allowing the helicopter to rise vertically or hover.

Tilting the spinning rotor will cause flight in the direction of the tilt.

helicopter tail rotor

The Tail Rotor

The tail rotor is very important. If you spin a rotor using an engine, the rotor will rotate, but the engine and the helicopter will try to rotate in the opposite direction.

helicopter torque
This is called


The tail rotor is used like a small propeller, to pull against torque reaction and hold the helicopter straight.

By applying more or less pitch (angle) to the tail rotor blades it can be used to make the helicopter turn left or right, becoming a rudder. The tail rotor is connected to the main rotor through a gearbox.

When using the tail rotor trying to compensate the torque, the result is an excess of force in the direction for which the tail rotor is meant to compensate, which will tend to make the helicopter drift sideways. Pilots tend to compensate by applying a little cyclic pitch, but designers also help the situation by setting up the control rigging to compensate.

The result is that many helicopters tend to lean to one side in the hover and often touch down consistently on one wheel first. On the other hand if you observe a hovering helicopter head-on you will often note that the rotor is slightly tilted. All this is a manifestation of the drift phenomenon.

The engine(s) simply drive the rotors and did not assist directly with forward flight (like they would with a plane). There is a very small amount of thrust that comes from engine exhaust, but it is so small that it does not effect flight performance.

User Contributed Notes

james pratt ( gardner mass )
My idea of how things work was correct this comfirms this and made me alot calmer i am really into this now.This realy is helpfull thankyou

suraj ( india )
that was a wonderful theory ,good phrases & very easy to understand about the helicopters

mario Maldonado ( Incline Village Nv )
Flying an helicopter is my dream! I want to express my appreciation to all of you who make possible this priceless teachings. Gracias mil, Mario

Martin Daniels ( Zambia )
Excellent explications keep it up guys

Sunday Oghenemaga Famous ( Nigeria )
This is a detailed and comprehensive theory. I have learnt alot from it

saugat sigdel ( nepal )
i was very curious know how helicopter and i was trying to find it in net but i was unsucessful . Now i have find that in this site. Thank you.

shahnoor ( India )
something was missing when i use other site .but this is a perfect theory and sufficient.

shanavas ( india )
simlple language easy to understand

Daeinstein ( Darlawn )
Whew... At last!! I got it... thanx this site is GREAT

ramesh khadson ( jabalpur(M.P) )
Hello I think this is the most easiest way to tell the principle of flying of Helocopter in so short with the help of Video. I think other would also learn from the above Ramesh Khadson

emmanuel absalom mwakasumi ( tanzania )
thanks,its more than answer to my question.

zeeshan asghar ( pakistan )
I learned a lot specially about forward flight....

Longwe Richard ( Malawi )
Thanks for this website, the issue on how helicopter flys has been well described and i have full knowledge on the matter. Once more thanks

Fakorede Solomon Oguns ( Nigeria )
Thank you so much .I got a very good answer to my question but would want u to assist me in building one.....

Oliver ( UK )
This may have of just saved me from failing a test in physics worth 25% of the total GCSE, Thanks :D

J.Chiaga ( Starlite Aviation )
just doing my cpl on helicopter and have to acknowledge that u guys have made me digest the rotorcraft concepts through ur contributions. Keep it up.

Joji ( Oman )
the way of detailing is very nice.

David Alec Materu ( Tanzania )
Bravo..I got a very good answer. Was just a more than answer to my question.

Elvis daniel ( Nigeria )
Your explaination was excellent i am impressed

taufiq ( indonesia )
simple phrase explanation is really help me, since this is the first time I get the reason why the helicopter can fly.

prakash sahoo ( odisha )
This is really a fantastic theory about helicopter. I think it will help many persons a lot,thaks .

tunde mobayo ( nigeria )
Thanks, your explanation is simple and educative

Kimutai Kirui G. ( Bomet, Kenya. )
You added a nice taste to my personal study on helicopters. Thanks a lot!B-)

Abdullahi Ahmed ( Beledweyne, Somalia )
Thank you for the easy explanation, this pushes forward my flying dreams.

Ogbeta Francis A. ( Lagos Nigeria )
Thanks, you hit the nail right on the head,easy to understand, thanks a million.

caleb ( g-burg )
very interesting I am interested in the flying machine, particularly in the vertical lift category

suraj godase ( India )
Thank u for clearing the idea of torque reaction

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