Time delay effects can be used to establish the penalty for performing assembly remotely from the ground. The range of time delays considered in Ref 24 was between zero and two seconds. If it is assumed that a manned manipulator will perform with time delay near zero and remote controlled manipulators will perform with time delays near two seconds, little difference in total time to perform the assembly tasks can be identified. Figure 3.4-15 presents the variation in complexity factor (time in dynamic environment/ time in static environment) for variations in target limit cycle deadband, manipulator characteristic frequency and the distance between the target eg and manipulator attach point for a system with a two second time delay. A similar plot for a system with zero time delay shows little variation in complexity factor for target limit cycle amplitudes of less than 1° and low manipulator characteristic frequencies. Manned free flyer module propellant consumption will vary between 14 and 16 lb (6.3 to 7.2 Kg) for the minimum and maximum time case, respectively. This quantity per trip includes limit cycle control and translational propellants. These estimates assume a 3000 lb (1359 Kg) vehicle with inertia and jet geometries similar to the Lunar Module (LM) ascent stage at docking. The ECS consumables required for life support will be approximately 0.2 to 0.3 lb (0.1 Kg) per trip. This estimate is based on the LM configured for one man. An unmanned manipulator module could be configured at 400 lb (181 Kg). This lower weight reduces propellant consumption to reasonable levels, 1. 8 to 2.1 lb (0.9 Kg) per trip. The order of magnitude difference in propellant consumption for the unmanned, relative to a manned free flyer, is a strong factor in favor of remote controlled assembly approaches. Figure 3.4-16 presents assembly cost factors which utilize the operations time line analysis results. The overall structure can be assembled at a rate of 13 to 26 Ib/m-hr (6 to 12 Kg/m-hr). This range of cost was established by determining the number of joints in a typical 108m x 108m primary/secondary structural bay (394) and the time to assemble, established in Fig. 3. 4-14, for each joint. The rate in units of Ib/m-hr is established by dividing the weight of a typical structural bay by the total time. These assembly rates are in line with that assumed during Task 1, 11 Ib/m-hr. This is the rate at which steel workers can construct a major building on the ground assuming aluminum girders. 3.4. 2.1.4 Assembly Using EVA Operations - Little or no data exist concerning large scale EVA assembly operations from which an extrapolation of task and time estimates can be made. This was determined after a survey of the literature and conversations with NASA personnel. However, actual EVA performance on Skylab equaled or exceeded expectations
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