RC India

General Topics => Beginners Zone => Topic started by: aerodev on October 29, 2013, 11:26:52 AM



Title: Take off distance calculation
Post by: aerodev on October 29, 2013, 11:26:52 AM
How do we calculate the take off distance for a given electric motor powered RC plane??
What all parameters do we need to know and what all assumptions to make?
Please explain in detail..

Thanks in advance


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Title: Re: Take off distance calculation
Post by: saikat on October 29, 2013, 12:35:01 PM
http://www.dmjwilliams.co.uk/gbsep_performance.htm#takeoff_calculator

check out the above link - this is for each individual aircraft so first
you have to specify what aircraft you have in mind and give the full
technical specifications - then only we can tailor make a distance calculator.

- better still talk to an airline or airforce pilot they can give you detailed explanation.

such level of academics is useless for model flying


Title: Re: Take off distance calculation
Post by: anwar on October 29, 2013, 01:32:06 PM
Very hard to give exact figures... taking into account all the factors you need to consider.

1. Wind
2. Direction of aircraft in relation to wind.
3. Speed of take off
4. Lift produced by wing... which means you have to take the design of the aircraft (factors like whether it is a biplane, airfoil shaped wings, whether it has flaps etc etc etc into account).
5. Other things like elevation of airfield... (now we are seriously nitpicking!).

Saikat da said it best... it is a useless academic exercise when it comes to model flying.

One windy days, you can let go of some small planes by just releasing them from your hands ;) (without even have to chuck them!)


Title: Re: Take off distance calculation
Post by: aerodev on October 30, 2013, 12:01:24 AM
Thanks saikat and anwar

Actually I am participating in a competition where my plane has to take off in 12 metres.
So I need to do this exercise of calculating take off distance, before starting construction.
I don't mind doing a trial and error method to find the take off distance.
But after constructing the plane if it doesn't takeoff within the mentioned length it will be all waste.

At this point I can make some aerodynamic assumptions but I need to have some idea of the take off distance..

The link saikat posted asks for ambient conditions and only plane's weight and nothing about the motor and lift.

I think the take off distance would depend on the weight, lift, drag and power of the motor.
Let me know if I am thinking in the right direction.
Just need to find the right link between all these parameters..


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Title: Re: Take off distance calculation
Post by: v2 eagle on October 30, 2013, 07:05:13 AM
Is it enough if it lift of the ground by few inches, say 4-10?
because 12 meters is roughly a tourist bus length and model planes will take off in this given distance normally(as far as ive seen) have a look at nearby field and see what you can do to improve it.

Ashok.