launch.gms : Launch Vehicle Design and Costing

**Description**

This model designs a three stage launch vehicle, taking into account cost-estimation relationships for R&D and production costs for airframe, engines and an instrument unit.

**Reference**

- Bracken, J, and McCormick, G P, Chapter 7. In Selected Applications of Nonlinear Programming. John Wiley and Sons, New York, 1968, pp. 58-82.

**Small Model of Type :** NLP

**Category :** GAMS Model library

**Main file :** launch.gms

```
$title Launch Vehicle Design (LAUNCH,SEQ=161)
$Ontext
This model designs a three stage launch vehicle, taking into
account cost-estimation relationships for R&D and production costs
for airframe, engines and an instrument unit.
Bracken, J, and McCormick, G P, Chapter 7. In Selected Applications
of Nonlinear Programming. John Wiley and Sons, New York, 1968,
pp. 58-82.
$Offtext
sets s stages / stage-1, stage-2, stage-3 /
b bound labels / lower, upper /
alias(s,ss);
sets ge(s,ss) s is greater than ss; ge(s,ss) = yes$(ord(s) >= ord(ss));
scalars pl pay load (thousands of pound) / 20 /
numl number of launches / 10 /
g average gravity (est) / 31.8 /
table pwbound(s,b) propellant weight
lower upper
stage-1 12 16
stage-2 10 12
stage-3 7 9
parameters
iwf(s) weight fraction / stage-1 .5, stage-2 .6, stage-3 .7 /
nume(s) number of engines / (stage-1,stage-2) 5, stage-3 1 /
rde1(s) Engine R&D cost 1 / (stage-1,stage-2) -257.963, stage-3 32.591 /
rde2(s) Engine R&D cost 2 / (stage-1,stage-2) 160.990, stage-3 181.806 /
rde3(s) Engine R&D cost 3 / (stage-1,stage-2) -0.146, stage-3 0.539 /
rde4(s) Engine R&D cost 4 / (stage-1,stage-2) 282.874, stage-3 232.570 /
rde5(s) Engine R&D cost 5 / (stage-1,stage-2) 0.648, stage-3 0.772 /
pre1(s) Engine cost 1 / (stage-1,stage-2) 0.2085, stage-3 0.0705 /
pre2(s) Engine cost 2 / (stage-1,stage-2) 2.509 , stage-3 -0.01807 /
pre3(s) Engine cost 3 / (stage-1,stage-2) 0.736 , stage-3 -1.33 /
pre4(s) Engine cost 4 / (stage-1,stage-2) 0.9744, stage-3 16.687 /
pre5(s) Engine cost 5 / (stage-1,stage-2) -0.229 , stage-3 0.498 / ;
* adjust from c*(x/100)**b to (c*10**b)*(x/1000)**b for stage-3
pre2('stage-3') = pre2('stage-3')*10**pre3('stage-3');
pre4('stage-3') = pre4('stage-3')*10**pre5('stage-3');
variables aweight(s) airframe weight (thousands of pounds)
iweight(s) inert weight (thousands of pounds)
pweight(s) propellant weight (thousands of pounds)
instweight instrument unit weight (thousands of pounds)
weight(s) total initial weight (thousands of pounds)
length(s) length of stage (feet)
thrust(s) thrust (thousands of pounds)
ethrust(s) single engine thrust (thousands of pounds)
ms(s) mass fraction
t2w(s) thrust to weight ratio
t(s) operating time
vfac(s) velocity factor
v(s) incremental velocity
vt total velocity
cost total cost;
equations diweight(s) definition of inert weight
dweight(s) definition of weight
dthrust(s) definition of thrust
t2wr(s) thrust to initial weight ratio definition
msd(s) mass fraction definition
pwlower(s) lower bound of propellant weight
pwupper(s) upper bound of propellant weight
defvfac(s) velocity factor definition
defv(s) definition of velocity
defvt definition of total velocity
costdef cost definition ;
diweight(s).. iwf(s)*iweight(s) =e= aweight(s);
dweight(s).. weight(s) =e= sum(ss$ge(ss,s), iweight(ss) + pweight(ss))
+ instweight + pl;
dthrust(s).. thrust(s) =e= nume(s)*ethrust(s);
t2wr(s).. t2w(s)*weight(s) =e= thrust(s);
msd(s).. (1-ms(s))*weight(s) =e= pweight(s);
pwlower(s).. pwbound(s,'lower')*iweight(s) =l= pweight(s);
pwupper(s).. pweight(s) =l= pwbound(s,'upper')*iweight(s);
defvfac(s).. vfac(s)*pweight(s) =e= thrust(s)*t(s);
defv(s).. v(s) =e= vfac(s)*g*log(1/ms(s));
defvt.. vt =e= sum(s, v(s));
costdef.. cost =e=
* airframe R&D cost
+ 5272.77*sum(s, aweight(s)**1.2781*iweight(s)**(-0.1959)*
ms(s)**2.4242*thrust(s)**0.38745*pweight(s)**(-0.9904))
* airframe production cost
+ .185214*sum(s, aweight(s)**0.3322*ms(s)**(-1.5935)*pweight(s)**0.2362*
length(s)**0.1079*nume(s)**0.1616*numl**0.9)
* engine R&D cost
+ sum(s, rde1(s) + rde2(s)*(ethrust(s)/1000)**rde3(s) + rde4(s)*(ethrust(s)/1000)**rde5(s))
* engine production cost
+ sum(s, ( pre1(s)*(ethrust(s)/1000) + pre2(s)*(ethrust(s)/1000)**pre3(s)
+ pre4(s)*(ethrust(s)/1000)**pre5(s))*(nume(s)*numl)**0.93)
* instrument unit
+ 10.35*(15822e-6*(instweight*1000)**0.786 - 35.5)
+ numl**0.9*15822e-6*(instweight*1000)**0.786
* launch operations
+ 8.5*numl*(3*sum(s, pweight(s))/1000)**0.460;
model launch / all /;
t2w.lo('stage-1') = 1.2; t2w.up('stage-1') = 1.4 ;
t2w.lo('stage-2') = .6; t2w.up('stage-2') = .75;
t2w.lo('stage-3') = .7; t2w.up('stage-3') = .9 ;
ms.lo('stage-1') = .25; ms.up('stage-1') = .30;
ms.lo('stage-2') = .24; ms.up('stage-2') = .29;
ms.lo('stage-3') = .16; ms.up('stage-3') = .21;
length.lo('stage-1') = 125; length.up('stage-1') = 150;
length.lo('stage-2') = 75; length.up('stage-2') = 100;
length.lo('stage-3') = 50; length.up('stage-3') = 70;
vfac.lo('stage-1') = 240; vfac.up('stage-1') = 290;
vfac.lo('stage-2') = 240; vfac.up('stage-2') = 290;
vfac.lo('stage-3') = 340; vfac.up('stage-3') = 375;
vt.lo = 35000; vt.up = 50000;
instweight.lo = 2.5; instweight.up = 4.0;
v.lo(s) = 1000;
t.lo(s) = 100;
thrust.lo(s) = 1;
aweight.lo(s) = 1;
iweight.lo(s) = 5;
pweight.lo(s) = 50;
ethrust.lo(s) = 20;
* this are the solution values the book
t.l ('stage-1') = 155;
t.l ('stage-2') = 314;
t.l ('stage-3') = 403;
iweight.l ('stage-1') = 136;
iweight.l ('stage-2') = 47;
iweight.l ('stage-3') = 16;
pweight.l ('stage-1') = 2176;
pweight.l ('stage-2') = 564;
pweight.l ('stage-3') = 144;
ethrust.l('stage-1') = 746;
ethrust.l('stage-2') = 96;
ethrust.l('stage-3') = 129;
length.l('stage-1') = 125;
length.l('stage-2') = 75;
length.l('stage-3') = 50;
ms.l('stage-1') = .3;
ms.l('stage-2') = .29;
ms.l('stage-3') = .21;
instweight.l = 2.5;
vt.l = 38632;
solve launch using nlp minmizing cost;
```