Explain the difference between limit load factors and

Question

Questions -

Part A -

Q1. Explain the difference between limit load factors and factors of safety.

Q2. Looking at example 15.3 in the text, your manager has asked you to see if titanium would be a better material than aluminum. Repeat the sizing of the face sheets using titanium and compare the results to aluminum and then also with quasi-isotropic graphite/epoxy face sheets ([0,+/-45,90]sym). Which material do you recommend and why?

Q3. You have conducted both testing and analysis of your spacecraft's structure and the following two matrices represent the test and model key mode shapes. How well does the model represent the actual structure? Justify your answer mathematically.

[modes](test): [1.02, 0.98, 0.99; 1.1, -0.379, -1.23; 1.11, -2.59, 3.21]

[modes](model): [1, 1, 1; 1, -0.382, -2.62; 1, -1.24, 3.24]

[mass]:[1, 0, 0; 0, 1,0; 0, 0, 0.5]

Q4. Determine the stiffness for a launch vehicle adapter for a satellite with center of mass 1.45 meters from launch vehicle and with a mass of 500 kg. Assume launch vehicle is a Delta II and the adapter length is 15 cm.

Part B -

Q1. A robot arm has two links, the 1st of 5 meters and the 2nd of 3 meters. If X hand is 4 meters, and Y hand is 1 meter, and θ hand is 350 degrees, use inverse kinematics to find θ₁, θ₂, θ₃.

Q2. Given an imaging system with 640x480 resolution and 24 bits/pixel, which would require less bits/second to transmit video: (a) a system with 30 frames per second and compression of 25%, or (b) a system transmitting 10 frames per second? For teleoperation of a robot arm, which system would you recommend and why?

Q3. Using what you know about radiative transfer, which location is best for a ground-based optical telescope, Florida or Arizona? Why? Would you then pick Florida or Los Angeles as a second choice? Why? If you were flying a spy satellite and wanted to see where a pavement runway was located in a smoggy location would you use 0.6μ or 1.2μ as your sensor wavelength? Why?

Q4. Are typical CCD sensors useful in the far IR? If you were offered the job of calibrating either a CCD sensor or a film camera system for intensity response, which job would you volunteer for and why?

Q5. What can be said about the relative temperature of yellow, red, and blue stars?

Q6. Does the moon or Mars provide a better location for the use of in-situ resources? Why do you feel this way? How do we get oxygen on the moon? On Mars? What is more beneficial in a site: (a) material to make oxygen, or (b) silicon for solar cells (for power, computer chips)?

Q7. Why did NASA decide that we were not ready (or it was not cost effective) to do a robotic servicing mission to HST, and instead decide that humans must do it? Do you think we could be ready in 10 years for robots to do such a job?

Q8. We learned that perigee drift is given by: = J_{2 2} (5cos2i - 1), where Re is the Earth's radius, a is the orbital semimajor axis, J2 is the flattening of the Earth's gravity field, and i is the orbital inclination. Find the critical inclination where the perigee drift goes to zero.

Q9. The space elevator is envisioned to be a rigid structure that moves around the Earth once in a day. Below the geostationary point, an object released would have less orbital energy. Above the geostationary point, an object released would have more orbital energy. Find the lowest radial distance (from the center of the Earth) where an object released would have escape velocity. Hint(s): escape velocity, ve, is ve = , and the velocity at release is proportional to the radial distance, v = rΩ, where Ω is the Earth's rotation, 1 revolution per day.

Q10. SMAD chapter 28.3 summarizes several mission design drivers that influence ground system design. Discuss any three of the following drivers: (a) Orbit/Trajectory, (b) Latency, (c) On-board Storage Capability, (d) Required Data Recovery Percentage, (e) Level of Automation.