STS Problem 0803A
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The Problem with the Space Shuttle and the Space Program Ali F. AbuTaha Fairfax, VA 1992, 2000, 2003 Table of Contents 1. Introduction ................................................................................................................................ 3 2. “I am not A Rocket Scientist, will I get it? .................................................................................... 5 3. The Space Shuttle ....................................................................................................................... 7 4. What Causes Dynamic Overshoot? .............................................................................................. 8 5. The Space Shuttle Designed to Static Loads Only ....................................................................... 12 5.1. Initial SSME’s Lift-off Specifications .................................................................................. 13 5.2. Initial SRB’s Lift-off Specifications ..................................................................................... 15 5.3. How was the Dynamic Overshoot Overlooked? .................................................................... 18 6. Dynamic Overshoot and the “$64,000 Question” ........................................................................ 23 7. Measurement of the Dynamic Overshoot in the Shuttle ............................................................... 25 8. Confusion Over the Dynamic Overshoot Measurements .............................................................. 29 8.1. Is SSME Thrust 1g? Engineers Ask the “$64,000 Question” .................................................. 31 8.2. Is the Base Bending Moment 700 MIP (million-inch-pounds)? .............................................. 33 8.3. Compounding the Dynamic Overshoot Error ........................................................................ 35 8.4. Erroneous Transient Illustrations ......................................................................................... 38 8.5. Flawed Transient Analysis .................................................................................................. 46 9. The Rampant Dynamic Overshoot Error ..................................................................................... 50 9.1. The Static Axial Force ........................................................................................................ 51 9.2. The Static O-Ring Seals Joint Rotation Parade ...................................................................... 56 10. Consequences of the Dynamic Overshoot ................................................................................... 63 10.1. Did the Tiles Fail at “Half” the Strength or “Twice” the Force? ........................................... 64 10.2. Number of Joint Pins Recklessly Doubled .......................................................................... 66 10.3. The BSM Design Thrust Doubled Outright ........................................................................ 69 10.4. Widespread Damage Due to Dynamic Overshoot ............................................................... 73 10.5. Massive Cracks in Launch Platform (MLP) ........................................................................ 78 10.6. Hubble Troubles and Dynamic Overshoot .......................................................................... 80 10.7. A Challenger-like Failure Happened Before? ...................................................................... 85 11. Dynamic Overshoot, the Space Program and Me ........................................................................ 88 12. Conclusion and Recommendations ........................................................................................... 104 Epilogue (2000) ...................................................................................................................... 111 References ............................................................................................................................. 127 Appendix ............................................................................................................................... 130 The Author ............................................................................................................................. 137 2 © 1992, 2000, 2003 Postscript – February 2003 It is time to fix the space program. The Columbia tragedy has again plunged NASA into a period of uncertainty, investigations and recovery. National leaders are calling to learn from past experiences, particularly, the Challenger investigations. My extensive investigation of the Challenger accident revealed a very serious error in the design of the Space Shuttle and other space hardware. This Report describes how, when, and why the mistake happened; and how one major design mistake by a few engineers has needlessly undermined the whole space program. The mistake may sound far-fetched. One engineer sent me an e-mail asking, “Is this Report a joke?” The major error is real. This Report is written so as to make the design blunder crystal clear to the student, teacher, professor, politician, lawyer, artist, scientist, engineer, reporter and others. Actually, the lengthy Report can be summarized in one plain paragraph: If you release a bag of potatoes suddenly on a weight-scale in a supermarket from zero height, you will see the dial overshoot the weight of the potatoes, oscillate and then settle down on the actual weight. The momentary overshoot is called the “dynamic overshoot.” Generally, the faster you release a force, the greater is the overshoot. The faster a rocket engine reaches its maximum thrust, the greater the dynamic overshoot and its adverse effects. The most important advances in the Shuttle program were the SSME (Space Shuttle Main Engine) and the SRB (Solid Rocket Booster). The SSMEs and SRBs packed more power that is released faster than anything we had before, and faster than any rocket engine used by the former Soviets or others. By neglecting the “dynamic overshoot” in Shuttle design in the 1970s, we shot ourselves in the foot. Ironically, everyone overlooked the dynamic overshoot effect in the design of his or her space hardware. Nonetheless, the former Soviets continued to launch 90 space missions annually in the 1970s and 80s primarily because their engines lumber to full thrust (hence, smaller dynamic overshoot), while we were reduced from 90 missions to a handful launches annually over the same period, primarily because our superior rockets jump to full thrust nearly instantly (hence, greater dynamic overshoot). In the meantime, great effort and resources were expended to pin down the “mysterious loads” that have been striking our space hardware with destructive effects. Have you ever read about the Shuttle “mysterious forces” in a newspaper or a magazine? The mysterious forces are caused by the dynamic overshoot that you will read about extensively in this Report. Our superior rockets of the 1970s became the invisible adversary of our space program. In this Report, I will discuss the scientific, technical, historical, psychological, philosophical and political elements of the dynamic overshoot problem. The reader will see that the issue is more a psychological problem than a complex engineering problem, which exposes a flawed thinking process on the part of otherwise generally competent 20th century rocket engineers. © 1992, 2000, 2003 3 1. Introduction You are about to plunge into a technical controversy that surrounds a massive engineering error, which has plagued the Space Shuttle, satellites, space probes and observatories. A serious error in the initial 1972 design of the Space Shuttle has undermined the effective operation and performance of the system. A first-order effect, known as the “dynamic overshoot,” was completely overlooked by the aerospace engineers since the beginning of the space program. The mistake went unnoticed even after the extensive Challenger Accident Investigations. The “dynamic overshoot” design error is described at length in this Report. The nature and the magnitude of the error are easy to perceive and there is plenty of supporting evidence. You will see why rockets built during the early stages of the space program had the bad habit of exploding on the launch pad and why every launch vehicle that was built experienced failures or outright explosions during development. You will see why many missions to Mars, Venus, Jupiter and elsewhere have either experienced serious malfunctions or were lost altogether. The same mistake explains why the Shuttle has averaged less than 5 problematic missions per year, instead of the originally planned 60 flawless annual flights. This Report describes how, when, and why the mistake happened. The consequential “dynamic overshoot” mistake was made in the design of almost all space vehicles and missions and almost all parts of the Shuttle and other hardware. This one error has undermined the whole space enterprise. I am an aerospace mechanical-structural-dynamics engineer. I began my aerospace career with COMSAT Labs in 1969. In the 1970s, I discovered that my co-workers had the proclivity to repeatedly make a specific serious design error, which is the same “dynamic overshoot” subject of this Report. Specifically, I eliminated the random explosion of spacecraft fuel tanks during tests in 1970, and I recorded the mistake and the fixes in technical memos (see Fig. 64). I left my aerospace job in 1978 because the Space Shuttle, which