How does water factor into rocket launches?

Submitted by teryret t3_10vu07s in space

I was just watching a video (namely: https://youtu.be/Ax6yV8ZC_bc?t=117) and the presenter mentioned that SpaceX has three basic options to keep from having to rip up all the concrete after each booster static fire: Come up with better concrete, dig a big trench, or to use a water deluge system. But then he goes on to say that "dig a big trench" isn't viable because it would be below the water table and thus flood.

... But who cares if it floods given that "water deluge" is one of the other options you're considering?

15

Comments

You must log in or register to comment.

croninsiglos t1_j7jg7ul wrote

Have you seen this?

https://youtube.com/shorts/Jzhmgw4FwW8?feature=share

Flooding 24/7 is different than water when you need it

13

teryret OP t1_j7jgtwf wrote

Huh. I hadn't thought about the airborne water as a sound suppression thing. That's super interesting. But I still don't quite see how that helps with the concrete.

4

croninsiglos t1_j7jh13n wrote

If you can minimize the damage to the concrete then you don’t have to repair it as often.

5

teryret OP t1_j7jh8rg wrote

...... right.....? And in what way does moving water do that better than always there water?

1

croninsiglos t1_j7jhibg wrote

You’re spraying it around the rocket it’s not just sitting in a large puddle underneath. The goal is to be between the source of the sound/vibrations and the concrete.

3

teryret OP t1_j7jibud wrote

Oh, I see what you're saying, you're saying the damage would be to the concrete around the periphery rather than immediately beneath the rocket. That makes sense, thanks!

2

Thorazine88 t1_j7ltmx5 wrote

I believe the issue is “Which is better: 1. A water deluge system which pours a huge amount of water between the rocket exhaust and the concrete pad. 2. A pool of water underneath the rocket exhaust.” I’m guessing a pool of water wouldn’t be as good because the rocket exhaust would blow hot water and steam everywhere in an uncontrolled manner.

2

Xeglor-The-Destroyer t1_j7mqqa9 wrote

A flat water surface might as well be concrete. It will reflect sound waves. The goal is to dampen the sound so you spray it through the air to disrupt the sound waves instead of reflect them.

3

Chork3983 t1_j7o2n91 wrote

I'd think it would just push the water out of the way right? Like if you have a puddle and you turn a leaf blower on it you'll blow the water away to expose the ground underneath. I'm thinking the same thing would happen in this case.

1

komatiitic t1_j7jjuel wrote

In addition to everything else because they're basically on the ocean the water that would flood the big hole would be salty, and salt water is bad for pretty much everything. Corrodes and degrades, so you probably don't want to be spraying it all over your very expensive rockets.

5

MrZorg58 t1_j7jh2dp wrote

The water serves two purposes. One to help keep the tower and such cooled. The other use is for sound suppression. Rockets are loud, and water dampens that sound pretty well.

4

Nydcn77 t1_j7jqhky wrote

Deluge systems have been used for a long time. At least as far back as Apollo. It absorbs the shock waves from all that thrust. It does some cooling but mostly absorbing shock by flashing to steam and cushioning the pressure waves. It's still basically a massive controlled explosion. You can see it really well in the Shuttle launches but not so much Apollo. What you also see is that the pad is pretty much incinerated. One of the reasons for long turn around times. As far as ditching the pads are raised and there is a large pit there to direct the thrust away from the pad. Search for launch pad videos on you tube.

4

abcxyztpgv2 t1_j7jh1kn wrote

Water is best sound suppression method. Concrete won't last long. Walls won't last. Not extensible. Not reusable for multiple launches. Can get cracks. Can blast and hurt rocket. Remember Colombia incident of 1 tiny tiny thing led to disaster. Water is best option.

1