Help Stuck On Sandtraps

[source29]

Im have just exited the pipes and have to fight two combines in this area.
I have tried several times and can not get by this area. (I can only kill the 1)

I read on the net that the is a crack in a wall Open it up with a grenade or
rocket, and go in.
Spin the wheels to turn of the gas, and continue down the
path. This then leads to chapter 9 Nova Prospekt.

Any info would be appriciated.

 

[CrazyJeepDriver]

If your fighting the gunships, there should be a large green crate of rockets as you move along. Take down the gunships with them, the second gunships crash should open up the hole in the wall for you to go through.