SHANGHAI JIAO TONG UNIVERSITY HALE UAV DESIGN Calculate Wpl Guess Wto_guess Calculate Wf/Wto Calculate WOE/Wto Figure Wto out Compare Wto and Wto guess Error<5%⑦ Yes No END Figure 4-1 Flowchart of primary weight estimation 4.2.1.Calculate WpL From the design requirement,WPL is 700 kg 4.2.2.Initial Wro Referring to RQ-4AA,of which the max take-off load is 11612 kg,we guess WTO GUESS=10000 kg. 4.2.3.Calculate Wr/Wro In order to calculate the mission fuel weight,fuel coefficient method is a reliable option.Then we need a typical mission profile.Considering our designis comparable to general jumbo-jet,we use the typical mission profile of civil airplane. -16-
HALE UAV DESIGN - 16 - Figure 4 - 1 Flowchart of primary weight estimation 4.2.1.Calculate WPL From the design requirement, WPL is 700 kg. 4.2.2.Initial WTO Referring to RQ-4AA, of which the max take-off load is 11612 kg, we guess WTO_GUESS = 10000 kg. 4.2.3.Calculate WF/WTO In order to calculate the mission fuel weight, fuel coefficient method is a reliable option. Then we need a typical mission profile. Considering our designis comparable to general jumbo-jet, we use the typical mission profile of civil airplane
上游夏大学 SHANGHAI JIAO TONG UNIVERSITY HALE UAV DESIGN 5 cruise engine warming up 6 circling groud sliding climbing 7 descending taking off 1 2 8 approaching landing Figure 4-2 Typical mission profile For each mission segment,there is an empirical fuel weight ratio or fuel weight ratio formula,listing below: Table 4-1 Mission segment weight fraction Mission segment Wi+1/Wi 1 engine warming up 0.985 2 ground sliding 0.985 3 taking off 0.985 4 climbing 0.985 5 cruise -RC exp V(LI D)CRUISE 6 circling -EC expL/D」 7 descending 0.99 8 approaching and landing 0.99 In this table W5/W4 is figured by Breguet range equation W:=exp -RC W V(LI D)CRUISE Where voyage R=10000 km cruise speed V=177 m/s, max lift-drag ratio L/D=18, while(L/D)cus=0.866L/D=15.588, sfc is chosen empirically according to high-bypass turbofans: -17-
HALE UAV DESIGN - 17 - Figure 4 - 2 Typical mission profile For each mission segment, there is an empirical fuel weight ratio or fuel weight ratio formula, listing below: Table 4 - 1 Mission segment weight fraction Mission segment Wi+1/Wi 1 engine warming up 0.985 2 ground sliding 0.985 3 taking off 0.985 4 climbing 0.985 5 cruise exp / CRUISE RC V L D 6 circling exp / EC L D 7 descending 0.99 8 approaching and landing 0.99 In this table W5/W4 is figured by Breguet range equation 5 4 exp / CRUISE W RC W V L D Where voyage R = 10000 km cruise speed V = 177 m/s, max lift-drag ratio L D/ = 18, while / CRUISE L D =0.866 L D/ = 15.588, sfc is chosen empirically according to high-bypass turbofans:
上海文夏大学 ANGHAI JIAO TONG UNIVERSITY HALE UAV DESIGN C=0.5kg/(daN.h)=0.000138kg/(kg·s) Then we get m;/形=exp-10000x103x0.000138, 177×15.588 =0.60445 Also we can get W。/W,=exp (L/D) Where circling time E=30min=1800s Then we get W。/W,=0.98629 Then fuel weight ratio is: We/Wo=1.06×(1-W/W) =1.06×(1-0.9854×0.60445×0.98629×0.992) =0.477 In which 1.06 is out of consideration of allowance for reserve and trapped fuel. 4.2.4.Calculate Wor/WTo WoE/Wro is usually fitted by an empirical formula: WoE I WTO=AW6·K Here provides some typical value of parameters(SD needed above of different category of air plane: Table 4-2 Parameters value of aircrafts Airplane type A C Agriculture aircraft 0.72 -0.03 Double turboprop aircraft 0.92 -0.05 Jet trainer 1.47 -0.10 Jet fighter 2.11 -0.13 Military transport 0.88 -0.07 Besides,K=1.04 when using variable swept back wing Or K=0.95~0.85 when using composite material. Considering our design,we choose an eclectic set of value:A=0.95 C=-0.07 -18-
HALE UAV DESIGN - 18 - C kg daN h kg kg s 0.5 / ( ) 0.000138 / ( ) Then we get 3 5 4 10000 10 0.000138 / exp( ) 177 15.588 W W 0.60445 Also we can get 6 5 / exp[ ] ( / ) EC W W L D , Where circling time E s 30min 1800 Then we get 6 5 W W/ 0.98629 Then fuel weight ratio is: 1 / 1.06 (1 / ) F TO i i i W W W W 4 2 1.06 (1 0.985 0.60445 0.98629 0.99 ) 0.477 In which 1.06 is out of consideration of allowance for reserve and trapped fuel. 4.2.4.Calculate WOE/WTO WOE/WTO is usually fitted by an empirical formula: / C W W A W K OE TO TO Here provides some typical value of parameters (SI) needed above of different category of air plane: Table 4 - 2 Parameters value of aircrafts Airplane type A C Agriculture aircraft 0.72 -0.03 Double turboprop aircraft 0.92 -0.05 Jet trainer 1.47 -0.10 Jet fighter 2.11 -0.13 Military transport 0.88 -0.07 Besides, K 1.04 when using variable swept back wing Or K 0.95 ~ 0.85 when using composite material. Considering our design, we choose an eclectic set of value: A=0.95 C=-0.07
上海文夏大学 SHANGHAI JIAO TONG UNIVERSITY HALE UAV DESIGN k=0.9,Then we get WE/Wo=0.95xW7×0.9 4.2.5.Iteration progress Using MatLab,we can easily get the value of Wro=9851 kg And here is the MatLab code: %%Primary weight estimation %2015/5/5 3 - V=640/3.6: 5- sfc=0.000138: 6- E=1800: LD=18: %max lift-drag ratio 8- R=10000e3: %voyage 9- mff=0.985"4*0.989*0.992*exp(-E*sfc/LD)*exp(-R*sfc/V/0.866/LD): 10- Wto_gus=10000: 11 Wp1=700: 12- Wf_to=1.06*(1-mff): 13- A=0.95:C=-0.07:k=0.9: 14- Wto=Wpl/(1-Wf_to-A*k*Wto_gus C) 15- while (abs ((Wto-Wto_gus)/Wto)>0.05) 16- Wto_gus=Wto: 17- Wto=Wpl/(1-Wf_to-A*k*Wto_gus'C) 18- end 19- disp(['Wto='num2str(Wto)]) 20- disp(['error='num2str(abs((Wto-Wto_gus)/Wto))]) 21- disp(['Wf/Wto='num2str(Wf_to)]) 马 disp (['Wf='num2str (Wf_to*Wto)]) 23 disp (['Woe/Wto=num2str (A*k*Wto_gus'C)] 24- disp (['Woe=num2str(Wto*A*k*Wto_gus'C)] Figure 4-3 MATLAB code And the convergent result is: >W estimation Wto=9851.0974 error=0.015115 Wf/Wto=0.48023 Wf=4730.8078 Woe/Wto=0.44871 Woe=4420.2897 MATLAB code for this calculation is in Zip file. 4.3.Estimation result In conclusion,we get an estimated Wro and several significative parameters for subsequent using. Here is our initial parameter design results: -19-
HALE UAV DESIGN - 19 - k=0.9, Then we get 0.07 W W W OE TO TO / 0.95 0.9 4.2.5.Iteration progress Using MatLab, we can easily get the value of WTO=9851 kg And here is the MatLab code: Figure 4 - 3 MATLAB code And the convergent result is: MATLAB code for this calculation is in Zip file. 4.3. Estimation result In conclusion, we get an estimated WTO and several significative parameters for subsequent using. Here is our initial parameter design results:
国 上游夏大学 SHANGHAI JAO TONG UNIVERSITY HALE UAV DESIGN Table 4-3 Initial parameter design results Wro 9851kg WElWio 0.48 Wr 4731kg WoE IWTo 0.449 WOE 4420kg -20-
HALE UAV DESIGN - 20 - Table 4 - 3 Initial parameter design results WTO 9851 kg / W W F TO 0.48 WF 4731 kg / W W OE TO 0.449 WOE 4420 kg