# Programatic equation for helicopter lift power gravity weight

having to build an app which is basically a helicopter

i need a formula to calculate the altitude gain working against gravity, weight of helicopter, lift and power of engin

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Commented:
well asking good old Newton should help you .. he made the "Newton's laws of motion". you dont have to implement it yourself, there are some physics-rigid-body-simulation-librarys out there. here is one:

http://www.ode.org/

ike
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Commented:
basically it is:

F = m * A

where:

m = mass (matrix)
A = acceleration  (vector)
F = force  (vector)

ike
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Commented:
if you want the helicopter to have a velocity of 5m/s after 2 seconds here is the formula for the acceleration needed:

A = delta-velocity  /  delta-time

A = 5m/s  /  2s

A = 2.5m/s²
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Author Commented:
ok im a bit of a dumb person when it comes to math (:-)

i have the following variables

gravity = 9.8
weight =  9,300 Lbs
Power = 1 - 100 this is created by a slider

i need to calculate what the lift will be to calculate what the altitude gain will be.

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Commented:
>> Power = 1 - 100 this is created by a slider

What does power mean ? How is power translated to acceleration ? Is the acceleration a linear function of the power ? (for a realistic engine that's not the case)
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Author Commented:

please eplain A = delta-velocity  /  delta-time

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Commented:
well power is work/time and work is force·distance

but how efficiently engine power is translated into lift power involves many factors beyond the scope of this question.

by the way, gravilty = 9.8 looks like your units are m/s^2
so if your units of mass are pounds, your units of power would be lb m^2/s^3
which is a strange mix of SI and Avoirdupois
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Commented:
>> but how efficiently engine power is translated into lift power involves many factors beyond the scope of this question.

I know ozo - I just want to know what Robinsonx6 wants to use. Power has a value between 1 and 100. What acceleration does a power of 1 mean ? And a power of 100 ? And a power of 50 ?
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Commented:
as infinity pointed out, ask yourself how realistic the simulation has to be.
what excactly are you trying to do? only lifting up the helicopter or moving it through a 3d-world

well about the formula: if you want to calculate the velocity of your object, in order to calculate the new position every frame, you need the following (for a simple euler-integration):

r -> current position
v -> current velocity
F -> force to apply to the object (the power of the engine)
m -> mass of the object
delta-t -> time elapsed since last calculation

(delta means change/difference to last known value, so if last frame was at
1.23 s and the currentframe is at 1.24 s, then delta-t is 0.01s)

(1) calculate the change of velocity:

F = m*A
A = F/m

delta-veloctiy = delta-t * A
velocity = velocity_last_frame + delta-veloctiy

(2)  calculate change of position using the velocity
delta-r = velocity * delta-t
r = r_last_frame + delta-r

r is the new position of your helicopter

ike
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Commented:
In one sense it seems to take no power to hover since the force is not being applied over a distance.
Just the ground does no work to hold up a helicopter sitting on it, since the force does not move the helicopter.
But what this overlooks, is that in order in applying the force to hover, air gets pushed down
and when you consider the movement of the air, there is a force over a distance.

If we assume that the air flows past a hovering helicopter at a velocity V, then the power necessary to hover is V*gravity*weight
If the helicopter wants an additional accelaration of a, the lift force needed would be gravity+a so the power needed would be V*(gravity+a)*9,300
(in practice, increasing the lift force to gravity+a may also increase V, but I don't know how to calculate how that so I'm ignoring it)
When the helicopter is rising a steady rate of v the power might be (V+v)*gravity*weight
Again, V+v is probably an oversimplification.
In addition, V may change with altitude, and weight may change as fuel is consumed.
g also changes with altitude, but you probably want to ignore that.
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Author Commented:
thanks i will be reviewing all this info later tonight thanks
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Commented:
If you are trying to design a model you need much more information than you have given
If you are trying to program a simulation , you must decide how much approximation you want to accept and exactly what variables you want to input. Make that number small.
To say power is between 1 and 100 is completely inadequate for anything but a simple programmed game.
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Author Commented:
reallly not sure how to close this question i hope im being fare
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