
ESA ExoMars launch - leowinterde
http://livestream.com/ESA/exomars
======
kartikkumar
In case you missed the launch:
[https://twitter.com/esa/status/709312126356201474](https://twitter.com/esa/status/709312126356201474)

------
sathackr
It seems to me that they launched that with a much higher TWR than
normal...the rocket seems like it accelerated much faster than I'm used to
seeing. Is that just the Russian way?

~~~
mikeash
The Proton-M's initial thrust-to-weight ratio is about 1.5, which is somewhat
high. Falcon 9 is about 1.2, and Delta IV Heavy is about 1.25, for comparison.
And of course since the Earth subtracts a constant 1, that means the
Proton-M's initial vertical acceleration is 2-2.5 times higher than those
examples.

I'm not sure why it's different. Higher TWR is more efficient (to a point),
but it also means there's potentially additional capacity to be had by
carrying more fuel. Maybe it has something to do with Proton's origins as a
gigantic ICBM, although that was a long time ago.

On a tangent, reading the Wikipedia entry for Proton-M, there have been 117
total launches and 11 failures. That's a mildly terrifying failure rate!

It occurred to me that with the Russians launching out of central Asia, there
must be some chunk of land to the east of there with a ton of rockets falling
on it, since even with a successful launch the first stages are just dropped.
I couldn't find much info on that, but there are some really cool pictures
here:

[http://www.eurasianet.org/departments/culture/articles/eav04...](http://www.eurasianet.org/departments/culture/articles/eav041902.shtml)

And some history here, but no rocket pictures:

[http://www.russianspaceweb.com/baikonur_downrange.html](http://www.russianspaceweb.com/baikonur_downrange.html)

~~~
sathackr
Thank you...I had googled exomars twr and came up empty.

~~~
mikeash
I don't think the payload matters much. Certainly its own weight is
insignificant compared to the rocket as a whole. I'm not sure if they might
load less fuel if the payload doesn't need full performance, but if so I think
that would be a relatively small effect as well.

I didn't find actual TWRs listed even just for the launchers, but you can find
the liftoff mass and thrust pretty easily, and just divide.

