1. September 26-28,1995
2. Thisfactormaybeusedtoimposethree differentboundaryconditionsonavery lowcost launchsystem: (a)payloadcostbasedon "fractionalexpendability"(definedbelow), (b)the "expectationvalue"of vehiclehardwarecost basedontheprobabilityof losingthe vehicle in anaccident,or (c)theamortizedcostof the vehicle, spreadacrossallof the payload-pounds thatthevehiclewill launchduringits"effective lifetime"(alsodefinedbelow). (Theselimitsare 95-4085
3. discussedingreater detail inMankins:AIAA-95-3138a).
4. Lastly,the costof the vehicleitselfcanonly be amortizedover the "effectivelifetime"of the highly reusablevehicle (HRV),which isdefined to bethe numberof flights madeduringthe term of thefinancing of the investment. Forexample, if the termof thefinancingis 10(ten)years,for the samecostas inthefirstexample,the "effective lifetime" mustbegreaterthan 2000 flights (200flights peryearfor 10years) if the relatedcostcontributionisto be lessthan $50 per payload-pound. Figure 3 providesa simplifiedgraphicaldepictionof the concept of how`Yractionalexpendability" providesa lower boundonthe achievablecost per payloadpound.