power calculations of multirotors uav

Calculation of Multirotor UAV Required Power

to calculate the power required for an uav rotor craft or multirotor uav you have to define your flight conditions and design requirements

Input Data:

a)     Flight Conditions:

Temperature, T

  Density, ρ

Specific Heat, Ɣ 

Gas Constant, Ru

b)    Design Requirement:

Gross Weight, W

Tip Mach number, M_t

Forward Velocity, V_f

 Climb Velocity, V_c  

Procedure of calculation:

1.   Tip speed, Ω_R

2.   Thrust Coefficient C_T

3.   Induced Velocity V_i

4.   inflow ratio ג

5.   Solidity σ

6.     Advance ratio μ

7.     Parasite Area 

8.     Power required

9.     Total Power

Power Calculations Matlab code:

a)     Code

clc

closeall

clearall

% INPUT DATA

%% 1- Flight Condition

T=288; rou=1.225; Ru=287; gama=1.4;

%% 2- Design Requirment

w=3*9.81; Mtip=0.2; Vc=2; Vf=0;

%% 3- Geometry available

C=0.03;  R=0.24; A=pi*R^2 ;

%% other Givens

K=1.15;  N=2; CDo=0.01;

% CALCULATIONS

% Tip speed

Vtip=Mtip*sqrt(gama*Ru*T)-Vf;

% Thrust Coefficint

Ct=(w)/(rou*A*Vtip^2);

% Induced Velocity

Vi=sqrt((w)/(2*rou*A));

%Inflow Ratio

lamdai=Vi/Vtip;

% inflow ratio >> climb

lamdac=Vc/Vtip;

% Solidity

S=(N*C)/(pi*R);

% Advance Ratio

mu=Vf/Vtip;

% Parasite area

f=0.1*A;

% Power Required

Pt=((K*lamdai*Ct)+(0.5*CDo*(1+K*mu^2))+(0.5*mu^3*(f/A))+(lamdac*Ct))*rou*A*Vtip^3

% total power included losses

P=1.1*Pt

% RPM

cp=(Pt/(rou*A*Vtip^3));

Q=cp*rou*A*Vtip^2*R;

omega=(Pt/Q)*(60/(2*pi))

b)    Results

P_T=  683watt

P=752watt

Ω=  2707  RPM

Variation of power with forward velocity:

a)     MatLab code

clc

closeall

clearall

T=288; rou=1.225; Ru=287; gama=1.4;

w=3*9.8; Mtip=0.2;

C=0.03;  R=0.24; A=pi*R^2 ;

K=1.15;  N=2; CDo=0.01; Vc=2;

Vf=0:0.01:30;

for i=1:length(Vf)

Vtip(i)=Mtip*sqrt(gama*Ru*T)-Vf(i);

Ct(i)=(w)/(rou*A*Vtip(i)^2);

Vi=sqrt((w)/(2*rou*A));

lamdai(i)=Vi/Vtip(i);

lamdac(i)=Vc/Vtip(i);

S=(N*C)/(pi*R);

mu(i)=Vf(i)/Vtip(i);

f=0.1*A;

Pt(i)=((K*lamdai(i)*Ct(i))+(0.5*CDo*(1+K*mu(i)^2))+(0.5*mu(i)^3*(f/A))+(lamdac(i)*Ct(i)))*rou*A*Vtip(i)^3;

P(i)=1.1*Pt(i);

end

figure(1)

plot(Vf,P/3,'linewidth',1.5)

gridon

xlabel('Forword Velocity (m/s)','fontsize',14)

ylabel('Power Required (watt) ','fontsize',14)

title('Power of one Rotor','fontsize',18)

figure(2)

plot(Vf,P,'linewidth',1.5)

gridon

xlabel('Forword Velocity (m/s)','fontsize',14)

ylabel('Power (watt) ','fontsize',14)

title('Performnce','fontsize',18)

b)    Results