Re: They said the APU fire is normal?

On Mar 29, 6:23 pm, Who Needs Fenders? <yea.ri...@xxxxxxxxx> wrote:
max...@xxxxxxxxxxxxxx wrote:
I'm not even so sure about the idea that one can "see the [APU] heat
being exhausted in the infrared for every night landing."

See: <http://tinyurl.com/2lr94x>

You must remember, in that shot, Discovery is still traveling at well
over 100 knots--the exhaust is being dissipated by the slipstream
between the vertical stabilizer and the OMS/RCS pods

In my own linked image, I don't believe the orbiter has touched down
yet. (Also, I'm not altogether certain that's an Edwards runway. I'm
going by the caption.)

(if you view the visible light version of the "on fire" landing,
even during rollout, the flames are dragged back along the body).

Are you now referring to STS-123, rather than STS-114? If you are
referring to STS-123, were APU flames visible prior to touchdown (in
either IR or color)?

But, that being said, if you look at video of that same landing (STS- 114http://tinyurl.com/25sg39), you can start to see the APU exhaust
"strobing" at the about the 1:16 mark.  And it looks like the still
image was taken just between "puffs" of exhaust some where around the
1:46-1:50 range of the video...  by that time, the puffs are quite
clearly visible (in IR).

I'm still a bit handicapped here, with no YouTube access. In the range
of time you mention above, has the STS-114 orbiter touched down yet?

Now, changing gears here: I'm wondering if we're all "arguing" about
this just because the commentator used the word "normal" to describe the
fire.  I wonder if he should have said the phrase "not unexpected".  As
described elsewhere, the exhaust is flammable... maybe this is the first
time it stayed alight all the way to the ground--every other time, the
slipstream was able to put it out well before going sub-sonic...

After looking again at a fairly old IR landing video, I'm developing
an airflow theory of my own that offers a different explanation. If
there's enough cooperative interest here, I might be willing to
capture that video and upload it to my website. After that, I would be
happy to offer you my theory and explain how I came up with it. I find
your comments constructive, thanks.

JTM
.

Relevant Pages

  • Re: They said the APU fire is normal?
    ... visible light version of the "on fire" landing, even during rollout, the ... But, that being said, if you look at video of that same landing, you can start to see the APU exhaust ...
    (sci.space.shuttle)
  • Re: They said the APU fire is normal?
    ... You must remember, in that shot, Discovery is still traveling at well over 100 knots--the exhaust is being dissipated by the slipstream between the vertical stabilizer and the OMS/RCS pods (if you view the visible light version of the "on fire" landing, even during rollout, the flames are dragged back along the body). ... And it looks like the still image was taken just between "puffs" of exhaust some where around the 1:46-1:50 range of the video... ...
    (sci.space.shuttle)
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