Conflict episode

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>I was just watching the episode Conflict and was wondering if the references
>to reentry angle are bloopers. Freeman mentions the spacecraft's reentry
>angle is too shallow. At this point, I think the entry angle was something
>like 7 degrees, Colonel Freeman tells Foster to cut back to 5 degrees.
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>I assume the lower the value, the shallower the reentry angle is. To me it
>is like the grade percentage of a road. If the grade is 5%, it isn't as
>steep as a road with a 7% grade.
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>Does anybody know if this is a blooper, or if the terminology used in the
>episode was correct?
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>Ron
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>I've been thinking a bit more about about this flight path angle
>thing in CONFLICT. It's quite possible that what they are calling
>"flight path" in UFO is actually what the aerospace industry calls
>"angle of attack". If this is true, then what we see in UFO makes a
>lot more sense.
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>The angle of attack is the angle between the direction you are
>travelling and the direction of the longitudinal axis of your
>vehicle. So if you are travelling at an angle of -45 degrees and
>your vehicle is pointed at -35 degrees, then your vehicle's angle of
>attack is +10 degrees. In an airplane, the angle of attack is used
>to generate lift, an upwards force which keeps it up in the air.
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>In UFO, the angle of attack of the lunar module is a critical factor
>in slowing it down from "space speeds" to "earth speeds". The
>shallower you fly, the higher the angle of attack (like the 8 degrees
>we saw on the gauge), and the flat surface of the bottom of the lunar
>module would generate more lift, which *could* cause the lunar
>modules to "skip" like a rock thrown into the water at a shallow
>angle. A steeper reentry would cause a lower angle of attack (like
>the 3 degrees we saw on the gauge), and the flat surface on the
>bottom would not generate as much lift, which means the lunar module
>would not slow down enough during reentry, and the high speeds and
>would cause the vehicle to overheat and burn up in the Earth's
>atmosphere.
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>I should stress again, that although the lunar module could indeed
>"skip" like a rock thrown in the water, it would never be flung back
>into space due to this lift, just like a rock would never get flung
>high into the air by skipping on the water.
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>Pam writes:
>>This info seemed esp important to the
>>astronauts of Apollo 13 when they were trying to get back home with limited
>>power source and limited computer ability.
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>Yes, but on Apollo 13, I think that critical angle was indeed the
>"flight path angle", which determined whether their trajectory would
>successfully make it into the Earth's atmosphere, or whether they
>would miss the atmosphere entirely and be stuck in space. Such a
>thing is determined when you're still far out in space, not when
>you're a minute from reentry. On Apollo 13, the concern was with the
>direction the vehicle was travelling. On UFO, the concern was with
>the direction the vehicle was pointing. Two different things.
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>So, I guess the gauge really *does* make sense if you think of these
>angles as "angles of attack", and not "flight path angles".
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>Ron, are you sorry that you brought this subject up? :-)
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>--
>Marc Martin, [hidden email]
>(who once had a job calculating reentry trajectories of future space vehicles)
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