function SimplifiedSizing
%---------------------------------------------------------------------%
% Takeoff Weight Buildup: Mission Profile: %
% Simple Cruise %
% W0 = Wpayload + Wfuel + Wempty %
% W0 = Wpayload + W0(Wf/W0) + W0(We/W0) Crz %
% 2-----3 %
% W0 - W0(Wf/W0) - W0(We/W0) = Wpayload Clb / \ %
% / 4 Ltr %
% Wpayload / \ %
% W0 = ----------------- 0----1 5 %
% 1-(Wf/W0)-(We/W0) TO Lnd %
% %
% (Raymer, pg. 16) (Raymer, pg. 19) %
%---------------------------------------------------------------------%
hrTOs = 3600; %hours to seconds
ktsTOfps = 1.6878; %knots to feet per second
miTOft = 5280; %miles to feet
mphTOfps = 1.4667; %miles per hour to feet per second
%---------------------------------------------------------------------%
W1overW0 = 0.970; %estimated warmup and takeoff weight fraction
W2overW1 = 0.985; %estimated climb weight fraction (Raymer, pg. 20)
Rmi = 450; %design range in miles
%3 hr flight time
Rft = Rmi * miTOft; %range in feet
CbhpCRZ = 0.4; %typical piston-prop (variable
%pitch) SFC crz, lb/hr/bhp
%(Raymer, pg. 23)
VCRZmph = 150; %design cruise speed in mph
%faster than driving
VCRZfps = VCRZmph * mphTOfps; %crz spd in feet per second
np = 0.8; %assumed prop efficiency
%(Raymer, pg. 23)
CCRZperhr = CbhpCRZ * VCRZfps/(550*np); %equivalent-thrust SFC
%crz, 1/hr (Raymer, pg. 23)
CCRZpers = CCRZperhr * (1/hrTOs); %1/s
A = 8; %statistical aspect ratio (Raymer, pg. 59)
SwetSref = 5; %estimated wetted area ratio (Raymer, pg. 25)
WettedA = A/SwetSref; %wetted aspect ratio (Raymer, pg. 26)
LDmax = 14; %estimated max lift/drag (Raymer, pg. 26)
LDCRZ = 1 * LDmax; %lift/drag crz (Raymer, pg. 27)
W3overW2 = exp( -Rft*CCRZpers / ... %estimated crz weight fraction
(VCRZfps*LDCRZ) ); %(Raymer, pg. 21)
Ehr = 3/4; %hrs, design ltr time to meet
%FAA IFR req (Raymer, pg. 18)
Es = Ehr * hrTOs; %loiter time in seconds
CbhpLTR = 0.5; %SFC in loiter, lb/hr/bhp
%(Raymer, pg. 23)
VLTRkts = 100; %assumed loiter speed
%(Raymer, pg. 105)
VLTRfps = VLTRkts * ktsTOfps; %fps
CLTRperhr = CbhpLTR * VLTRfps/(550*np); %equivalent-thrust SFC
%in ltr, 1/hr (Raymer, pg. 23)
CLTRpers = CLTRperhr * (1/hrTOs); %1/s
LDLTR = 0.866 * LDmax; %lift/drag ltr (Raymer, pg. 27)
W4overW3 = exp( -Es*CLTRpers / LDLTR ); %estimated loiter weight
%fraction (Raymer, pg. 21)
W5overW4 = 0.995; %estimated landing weight
%fraction (Raymer, pg. 20)
W5overW0 = W1overW0 * W2overW1 * ... %total mission weight
W3overW2 * W4overW3 * W5overW4; %fraction (Raymer, pg. 27)
WfoverW0 = 1.06 * (1-W5overW0); %total fuel fraction with
%reserve/trapped fuel
%(Raymer, pg. 27)
W0guess = 8000; %takeoff weight guess in pounds
W0calc = 0; %initialized calculated takeoff weight
WeW0vsW0A = 1.09; %statistical empty weight fraction vs TO weight
WeW0vsW0C = -0.05; %(Raymer, pg. 18)
WeW0vsW0Kvs = 1; %fixed sweep
Wpayload = 2000; %design payload weight in lbs
count = 0; %number of iterations
while abs(W0guess-W0calc) > 1
WeoverW0 = WeW0vsW0A * W0guess^WeW0vsW0C * ... %empty weight
WeW0vsW0Kvs; %fraction
W0calc = Wpayload / (1-WfoverW0-WeoverW0); %takeoff weight, lb
%(Raymer, pg. 16)
W0guess = 0.9 * (W0calc-W0guess) + W0guess; %new W0guess
count = count + 1; %increment count
end
W0 = W0calc; %takeoff weight
Wempty = W0calc * WeoverW0; %empty weight
Wfuel = W0calc * WfoverW0; %total fuel weight
Wfueluse = W0calc * (1-W5overW0); %usable fuel weight
%---------------------------------------------------------------------%
disp(' ');
disp('SIMPLIFIED SIZING:');
disp(' ');
disp(['Range = ',num2str(Rmi),' miles']);
disp(['Cruise Speed = ',num2str(VCRZmph),' mph']);
disp(['Loiter Time = ',num2str(Ehr),' hrs']);
disp(' ');
disp(['Wetted Aspect Ratio = ',num2str(WettedA)]);
disp(['Aspect Ratio = ',num2str(A)]);
disp(['Max L/D = ',num2str(LDmax)]);
disp(' ');
disp(['Takeoff Weight = ',num2str(W0),' lbs']);
disp(['Empty Weight = ',num2str(Wempty),' lbs']);
disp(['Payload Weight = ',num2str(Wpayload),' lbs']);
disp(['Fuel Weight = ',num2str(Wfuel),' lbs']);
disp(['Usable Fuel = ',num2str(Wfueluse),' lbs']);
disp(' ');
disp(' ');
%---------------------------------------------------------------------%
