The impact of launch vehicle type and size on development cost

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  • Acta Astrmmutica Vol. 8, No. 11-12, pp. 1195--1205, 1961 Printed in Great Britain

    0094-5765/8 I/I I 1195--I 1502.00/0 Pergamon Press Ltd.

    The impact of launch vehicle type and size on development costt

    DIETRICH E. KOELLE~: MBB Space Division, Ottobrunn, F.R.G.

    (Received 5 May 1981)

    Abst~ct--The technical development trend of future launch vehicle systems is towards fully reusable systems, in order to reduce space transportation cost. However, different types of launch vehicles are feasible, as there are

    --winged two-stage systems (WTS) --ballistic single-stage vehicles (BSS) --ballistic two-stage vehicles (BTS)

    The performance of those systems is compared according to the present state of the art as well as the development cost, based on the "TRANSCOST-ModeI". The development costs are shown versus launch mass (GLOW) and pay-load for the three types of reusable systems mentioned above.

    It is shown that performance optimization and cost minimization lead to different results. It is more economic to increase the vehicle size for achieving higher performance, instead of increasing technical complexity.

    Finally it is described that due to the essentially lower launch cost of reusable vehicles it will be feasible to recover the development cost by an amortization charge on the launch cost. This possibility, however, would allow commercial funding of future launch vehicle developments.

    1. Intreduction THE TECHNICAL development trend of future launch vehicle systems is towards fully reusable systems, in order to reduce the presently very high cost of space transportation with expendable vehicles.

    However, different types of launch vehicles concepts are being considered as future candidates for Earth to LEO transportation as there are

    WINGED TWO-STAGE SYSTEMS (WTS) BALLISTIC SINGLE-STAGE SYSTEMS (BSS) BALLISTIC TWO-STAGE VEHICLES (BTS).

    These systems have different performance, different flight operations cost and different development cost.

    tPaper presented at the XXXlst Congress of the International Astronautical Federation, Tokyo, Japan, 22-27 September 1980 (Paper No. 80-IAA'35).

    ~;Dr.-lng., Head of Advanced Space Systems and Technology Development, Messerschmitt- BOlkow-Blohm GmbH (MBB) Space Division; Academy Member (Section 2).

    1195

  • 1196 D.E. Koelle

    Development cost are important because they represent the hurdle to be overcome for any new vehicle development.

    It is important to realize the magnitude and sensitivit~ of development cost with respect to size, respectively performance. This will be analyzed by a cost model based on statistical reference points.

    2. The cost model structure The development cost analysis is based on the "TRANSCOST"-Model,

    developed by MBB for ESA [1]. Figure 1 shows the structure of the model which is using specific CERs (Cost

    estimation relationships) for vehicle stages and propulsion elements. The development cost are defined as such without the flight (test) vehicles and operations cost which are taken from special sub-models.

    The complete program development cost are expressed as follows:

    with Hs = development efort for one stage system, HB = development effort for one engine type, CF =total fabrication cost of n flight test vehicles, and Co = total operations cost for n flight tests.

    The factor 1.1 takes into account 10% additional cost for system engineering, integration and test of the complete vehicle.

    The CERs are derived statistically by using realistic reference points. Figure 2 shows as an example the stage system specific development cost. The cost relationship for expendable stages H~--3140-M -~ (MY) is based on the SATURN 5 stages, all developed at the same time with the same technology (M = net mass).

    The cost unit used in this model is MY = Man Year, the equivalent to the total cost divided by productive manhours. The reason for using this unit is that it remains constant over time, independent from inflation and currency exchange factors. The cost of 1 MY 1981 are about 100,000 US$ or 72,000 AU.

    For manned winged vehicles the only realistic reference point is the Shuttle Orbiter (without SSME development cost). The relevant CER has been defined such that it has the same trend vs size like the CER for the expendable stages, defined by a reference point 25% lower than the Orbiter cost. As the first of its kind the development costs are about 25% higher than consecutive systems. The resulting CER for the development cost is

    Hu = 6500. M '21 (MY)

    indicating that the development costs for manned winged systems are higher by a factor 2 compared to expendable stages. This is confirmed by relevant cost estimates by Boeing for their HLLV concepts (see Fig. 2).

    For unmanned ballistic reusable stages no reference point exists yet, there- fore the assumption has been taken that it will be between the values for

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  • The impact of launch vehicle type and size on development cost 1199

    expendable stages and manned winged systems, or about a factor 1.3 more expensive than expendable stages. In fact the costs will be higher than factor 1.3 or 2.0 for reusable systems of the same performance because of their higher net mass.

    The net mass of the systems is highly important since all CERs are using the mass (in kg) as reference. Therefore, the CERs are related to the same and similar technology (neither very advanced nor intentionally simple or crude technology).

    The complete CER is defined by

    H=a .M x "fl "f2

    with H = development effort in MY, a, x = specific values for each type of equipment or system (defining slope and level of the reference curve), M = the reference system mass in kg, f~ = influence of the technical development stan- dard, and f2 = technical quality factor, defined differently for each type of system.

    The f~ influence factor is defined as follows:

    --first generation system --second generation, but new

    team/company --technology already proven --same system as already built

    by the same team/company

    fl = 1.25

    fl = 1.0 fl = 0.8--0.9

    fl = 0 .5 -0 .8 .

    3. Launch vehicle performance characteristics The cost model is using the net mass for reference, therefore, in a general

    comparison the net ma~s for different types of stage systems and sizes is required.

    Figure 3 shows the result of the analysis based on