Solidified concrete glass is typically black or dark green.
On Mon, Sep 12, 2016 at 2:03 PM, Robert Watzlavick
<rocket@xxxxxxxxxxxxxx> wrote:
What is the black surface over the bricks? It looks like a 1/2 inch coating
of sorts.
-Bob
On Sep 12, 2016, at 12:39, Carl Tedesco <ctedesco@xxxxxxxxxxxxxx> wrote:
Here's an exhaust deflector I made...
https://www.youtube.com/watch?v=irJEIJ3OVZY
It used a special concrete additive made for fireplaces. Like the pavers and
bricks, it too has a finite life under these conditions. The end of the
deflector is angled upward by 5 degrees to get the exhaust off the ground
which is good for video/photography when testing on a dirt surface.
--- Carl
On Mon, Sep 12, 2016 at 10:05 AM, Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Mon, 12 Sep 2016, Robert Watzlavick wrote:
...Or maybe an aluminum one with tubing welded on the back with water
running through it.
The main question would be how hot the surface would get. An impinging
rocket exhaust is the mother of all convective heat transfer systems, so
even with water right behind the surface, there'll be a serious temperature
gradient from front to back. You have to keep that low enough that the
surface layer doesn't melt, despite a thin and surely turbulent boundary
layer. Could be quite a challenge.
Henry
