SpaceX Tuesday...
Discussion
There was a leak in one of the Russian sections a few weeks ago, but they fixed that. Apparently they released some tea leaves into the section, then came back a few hours later. The leaking air had pulled the drifting tea towards it, giving itself away. Pretty ghetto, but it worked.
Elon expanded on the reasons for losing the Raptor engine on Starship SN8 the other day:
"About 2 secs after starting engines, martyte covering concrete below shattered, sending blades of hardened rock into engine bay. One rock blade severed avionics cable, causing bad shutdown of Raptor."
"Avionics cables moving to steel pipe shields & adding water-cooled steel pipes to test pad"
Martyte seems to be an epoxy / ceramic compound used to protect construction steel, concrete, water deluge systems in flame trenches etc. It was originally developed by Martin Marietta (now Lockheed Martin).
Sounds like they need a taller launch stand as well.
"About 2 secs after starting engines, martyte covering concrete below shattered, sending blades of hardened rock into engine bay. One rock blade severed avionics cable, causing bad shutdown of Raptor."
"Avionics cables moving to steel pipe shields & adding water-cooled steel pipes to test pad"
Martyte seems to be an epoxy / ceramic compound used to protect construction steel, concrete, water deluge systems in flame trenches etc. It was originally developed by Martin Marietta (now Lockheed Martin).
Sounds like they need a taller launch stand as well.
CraigyMc said:
Do rockets get any helpful thrust out of backpressure in ground effect?
It may not be as simple as lifting the base of the rocket off the deck.
I doubt it’s of much if any benefit. The Russians suspend their rockets over a deep flame pit after all. It’s the rocket’s engines rapidly throwing out hot gasses that thrust it forward, as per Newton’s laws. It’s not pushing against the ground as such. It may not be as simple as lifting the base of the rocket off the deck.
The blast & noise of launch must be directed away from the source, or as we’ve seen, it can cause physical damage to the rocket and the infrastructure. Hence the huge flame diverters and powerful water deluge systems at other sites. Neither of which the current set up at Boca Chica uses to any great extent as yet. A deep flame pit is not really practical at coastal locations like Cape Canaveral or Boca Chica, due to the high water table. At least in Florida they’re not very far from the limestone bedrock, so they were able to build up. At Boca Chica the bedrock is a long way down.
Rocket exhaust is brutal and will find any weakness. I recall that one of the Shuttle launches dislodged a large panel of fire bricks from the flame trench and flung them as far as the perimeter fence once. All the Apollo era firebricks have since been replaced at pad 39b in readiness for SLS operations from there.
Even with single-engine Raptor flights, they were tearing up the concrete. With 3 of them going full whack they’re really going to have to have everything nailed down. Let alone with Superheavy and its 28+ engines. They’re working on a new stand for that though, but it doesn’t look that impressive when you compare it with what even the French have done for their forthcoming Ariane 6 rocket.
https://youtu.be/4EWDpkEVNSg
CraigyMc said:
Beati Dogu said:
Sounds like they need a taller launch stand as well.
Do rockets get any helpful thrust out of backpressure in ground effect?It may not be as simple as lifting the base of the rocket off the deck.
Hence why Vacuum ISPs are more efficient, greater expansion.
Beati Dogu said:
Elon expanded on the reasons for losing the Raptor engine on Starship SN8 the other day:
"About 2 secs after starting engines, martyte covering concrete below shattered, sending blades of hardened rock into engine bay. One rock blade severed avionics cable, causing bad shutdown of Raptor."
"Avionics cables moving to steel pipe shields & adding water-cooled steel pipes to test pad"
Martyte seems to be an epoxy / ceramic compound used to protect construction steel, concrete, water deluge systems in flame trenches etc. It was originally developed by Martin Marietta (now Lockheed Martin).
Sounds like they need a taller launch stand as well.
Better to find this issue now with concrete rather than in a few years time with lunar regolith... "About 2 secs after starting engines, martyte covering concrete below shattered, sending blades of hardened rock into engine bay. One rock blade severed avionics cable, causing bad shutdown of Raptor."
"Avionics cables moving to steel pipe shields & adding water-cooled steel pipes to test pad"
Martyte seems to be an epoxy / ceramic compound used to protect construction steel, concrete, water deluge systems in flame trenches etc. It was originally developed by Martin Marietta (now Lockheed Martin).
Sounds like they need a taller launch stand as well.
There's a couple more Falcon 9 launches coming up soon:
Saturday, Nov. 21st Falcon 9 at 5.17 pm UK time from Vandenberg Air Force Base, California. The first launch from there for well over a year.
This will carry the Sentinel 6A satellite. The booster will attempt to land back at the launch site.
The other one, Starlink-15 is on Monday morning 3.17 am UK time (Sunday at 10:17 pm local time).
This will be from SLC-40, Cape Canaveral Air Force Station, Florida
Saturday, Nov. 21st Falcon 9 at 5.17 pm UK time from Vandenberg Air Force Base, California. The first launch from there for well over a year.
This will carry the Sentinel 6A satellite. The booster will attempt to land back at the launch site.
The other one, Starlink-15 is on Monday morning 3.17 am UK time (Sunday at 10:17 pm local time).
This will be from SLC-40, Cape Canaveral Air Force Station, Florida
Flooble said:
Probably a stupid question, but if you dug a hole that filled with water (because of the high water table) would that actually be a bad thing? You want a water deluge anyway ...
You want water in the form of airborne spray as an acoustic absorber, not in the form of a pond under the vehicle
AJLintern said:
Yes why don't they launch rockets from tubes much like the barrel of a gun? Wouldn't it increase the efficiency of the launch...? 
Consider the pressure differential between the open end of the tube, and the closed end being violently filled with rocket exhaust, and then consider the stresses that would impose on the body of the rocket in the middle. Then envisage a hail of burning, crushed debris that used to be your rocket come flying out of the launch tube.
Well, they DO when it comes to ICBMs. However, they have to take massive precautions to make sure exhaust gases are vented as the rocket climbs up the tube.
The only reason they are in "tubes" (usually called "silos") is to hide them from spy satellites.
https://www.youtube.com/watch?v=xO-CE6SW7eo
The only reason they are in "tubes" (usually called "silos") is to hide them from spy satellites.
https://www.youtube.com/watch?v=xO-CE6SW7eo
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