% Analysis of Cessna 402b
clear all
echo on
% Start here
% Basic data
W=   6300  % maximum takeoff weight, lbf (pounds)
S=255.8    % Wing area square feet
rho=.002378  % air density, slugs/cubic foot
% Stall velocity is in the range between 73 and 83 knots.
% the aircraft that killed Aaliya was believed to have been overloaded
% by between 700 and 1500 pounds(lbf).


% Case 1: Assume stall speed is 83 knots and find CLmax
% This case is probably for flaps up stall speed.
Vstallknots=    83 % stall velocity, knots (nautical miles per hour)
Vstallfps=Vstallknots*1.687808   % ft/sec
CLmax=W/(.5*rho*Vstallfps*Vstallfps*S)

% Case 2: Assume stall speed is 73 knots and find CLmax
% This case is probably for flaps full down stall speed.
Vstallknots=    73 % stall velocity, knots (nautical miles per hour)
Vstallfps=Vstallknots*1.687808   % ft/sec
CLmax=W/(.5*rho*Vstallfps*Vstallfps*S)

% Case 3: Assume stall speed is 78 knots and find CLmax
% This case is probably a good representation for takeoff stall speed since takeoff
% is typically done with about half flaps.
Vstallknots=    78 % stall velocity, knots (nautical miles per hour)
Vstallfps=Vstallknots*1.687808   % ft/sec
CLmax=W/(.5*rho*Vstallfps*Vstallfps*S)
% This is the most likely value for CLmax for the takeoff configuration.
% Now we know a range of possible values for CLmax

% Case 4: Assume weight overload of 700 pounds and liftoff speed of 87 knots
% Find CLmax for this case and see how close it is to CLmax.
Woverload= 700  % lbf (pounds)
Vlofknots=  87   % liftoff velocity, knots (nautical miles per hour)
Vloffps=Vlofknots*1.687808   % liftoff speed, ft/sec
CLoverload=(W+Woverload)/(.5*rho*Vloffps*Vloffps*S)

% Case 5: Assume weight overload of 1500 pounds and liftoff speed of 87 knots
% Find CLmax for this case and see how close it is to CLmax.
Woverload2= 1500  % lbf (pounds)
Vlofknots=  87   % liftoff velocity, knots (nautical miles per hour)
Vloffps=Vlofknots*1.687808   % liftoff speed, ft/sec
CLoverload2=(W+Woverload2)/(.5*rho*Vloffps*Vloffps*S)
% This is very close to CLmax we computed for the half flap configuration (Case 3).
% This is probably what happened. The aircraft stalled because the pilot demanded 
% more lift then the wings could produce.

