Titan IVB question

Hello All,

I have a question about something I saw in the photos of this week's Titan
IVB launch. It is a phenomenon I've also seen in pictures of Titan III
launches going back to the first Titan IIIC in 1965.

In this week's launch the two liquid propellant core stage engines were not
firing at liftoff (they ignited at about T+2 minutes), yet they were lit up
white inside the nozzle bells and some kind of vapor was falling from their
nozzles. Was it a low-pressure flow of only fuel or oxidizer through the
engines to serve as a coolant against the radiant heat from the adjacent
solid rocket motor plumes?

Many thanks in advance to anyone who can help. -- J. Jason Wentworth

In article ,
James Wentworth wrote:
In this week's launch the two liquid propellant core stage engines were not
firing at liftoff (they ignited at about T+2 minutes), yet they were lit up
white inside the nozzle bells and some kind of vapor was falling from their
nozzles.

The vapor may just be condensation, in the low-pressure zone in the wake
of the nozzles. You can see this above airliner wings when landing in
humid air.

Similarly, the apparent illumination may be light from the SRB plumes
lighting up either the condensation or a protective nozzle plug.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

We have discussed this matter some time ago in one of the sci.space.*
groups.
Finaly, i got this mail from LockMart to clarify:

Betreff: Titan-4 core engines questions
Datum: Tue, 10 Sep 2002 17:49:47 -0600
Von: "McCollum, Evan D"
An: '"

The Stg I engines are protected from the Solids gasses by a boattail, a
heat
shield and the nozzles have exit closures that come off when they start as
the solids burn down. The image just shows gasses from the solids
swirling
around the stg I engines.

Evan McCollum

Gunter Krebs
www.skyrocket.de/space

"James Wentworth" schrieb im Newsbeitrag
...
Hello All,

I have a question about something I saw in the photos of this week's Titan
IVB launch. It is a phenomenon I've also seen in pictures of Titan III
launches going back to the first Titan IIIC in 1965.

In this week's launch the two liquid propellant core stage engines were
not
firing at liftoff (they ignited at about T+2 minutes), yet they were lit
up
white inside the nozzle bells and some kind of vapor was falling from
their
nozzles. Was it a low-pressure flow of only fuel or oxidizer through the
engines to serve as a coolant against the radiant heat from the adjacent
solid rocket motor plumes?

Many thanks in advance to anyone who can help. -- J. Jason Wentworth