Jochen Schischka (
History)
November 17, 2008 at 9:27 pm
Dear Mr. Forden,
i think you are definitely wrong in interpreting the fairings and the cable ducts on the sides of the first stage of the Sejil as fuel lines for a liquid-fueled vernier engine. As i wrote in my comment to Mr. Lewis’ article “Iran Claims Solid-Fueled 2 Stage Sejjil”, i think these fairings do bear a striking resemblance to the retro-rockets of russian missiles like the R-14/SS-5/Skean. The “piping” is just a cable duct for the associated wiring. If these ducts would contain fuel lines, wouldn’t you expect the lines for fuel and oxidiser to have different lengths (take a close look at the backside of the missile – both fairings end at the same height!)?
Furthermore, there are no additional flames next to the main-engine exhaust plume visible – compare this to known missiles with vernier-engines like the MR-UR-100/SS-17/Spanker or the R-29RM/SSN-23/Skiff.
And obviously, there is much less of a problem with graphite jet vanes and aluminized composites than we in the west do expect (although i still haven’t figured out how exactly this can work – there must be some kind of trick, maybe a special coating or additive). There are lots of examples for this configuration obviously working pretty well: Tochka/SS-21/Scarab, Iskander/SS-26/Stone, Pionier/SS-20/Saber, Topol/SS-25/Sickle, DF-11/M-11/Ghaznavi/CSS-7, DF-15/CSS-6, M-9/Shaheen-1 and M-18/Shaheen-2, just to name some of them. The only other material that i ever heard of being used in jet vanes was Molybdenum (on the successless german A3-experimental-missile – after that, the material of choice for A5 and A4 was…yup, graphite!), although i guess that modern hi-tech-composite-ceramics like SiC could perhaps also work.
To Pedro:
I completely agree with you!
(except if your intention was to suggest that the jet vanes on chinese solid-boosters were made of aluminum…a material with FAR too insufficient thermal properties; By the way, at certain angles graphite can look metallic shiny.)