Author Topic: Buran and debris  (Read 5451 times)

Offline gladiator1332

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Buran and debris
« on: 11/03/2005 09:33 PM »
I was thinking about the Energia Buran before and its similarities and differences to the Shuttle, when I wondered, did the Russians ever have the same problems we did?
In the one launch, was their any accounts on how much debris was shed off of the Energia launch vehicle? Are their any estimates whether there was more, less, or about the same as the Shuttle? This really has no technical purpose, I really am just wondering whether the same problems could have come up for the Russians.
The only reason why there might not be too much data, if any at all, on this, is that at the time of the Buran launch, debris shedding from the launch vehicle was not a known problem. No one really concentrated on that until STS-107.

Offline STS Tony

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RE: Buran and debris
« Reply #1 on: 11/03/2005 09:35 PM »
Buran's ET was painted wasn't it?

There's a load (and I mean a load) of images with the big video of Buran's first launch and landing - the last too).

Offline STS Tony

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RE: Buran and debris
« Reply #2 on: 11/03/2005 09:35 PM »
Sorry, here's a link. Damn good question all the same.

http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=636&start=1

Offline Matty Picard

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RE: Buran and debris
« Reply #3 on: 11/03/2005 09:37 PM »
Good one Glad. Wondered about this myself. Also wonder if STS 1 and 2 ever had problems or if they really were more concerned about getting her up more than worrying about anything coming off the ET. If paint stops debris then is it worth the weight saving to take it off in the first place!

Offline Orbiter Obvious

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RE: Buran and debris
« Reply #4 on: 11/03/2005 09:39 PM »
Quote
gladiator1332 - 3/11/2005  4:33 PM

I was thinking about the Energia Buran before and its similarities and differences to the Shuttle, when I wondered, did the Russians ever have the same problems we did?
In the one launch, was their any accounts on how much debris was shed off of the Energia launch vehicle? Are their any estimates whether there was more, less, or about the same as the Shuttle? This really has no technical purpose, I really am just wondering whether the same problems could have come up for the Russians.
The only reason why there might not be too much data, if any at all, on this, is that at the time of the Buran launch, debris shedding from the launch vehicle was not a known problem. No one really concentrated on that until STS-107.

I think everything stayed in place because the Russian tank was painted. Shame our Russian posters are in bed as they'd probably know. But that question about if debris wasn't an issue or not on the first two launches with a white painted ET is a good template to see.

I actually didn't know STS-2 was a painted ET too, I thought it was just STS-1. You learn something all the time.

Offline discovery_fan

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RE: Buran and debris
« Reply #5 on: 11/03/2005 10:17 PM »
As far as I know, but I could be wrong, a painted STS- ET does not behave different regarding foam shedding.
I think the paint was there for cosmetic reasons, and to shield the foam against weather and rain.
From what I know the usual reasons for foam shedding (like the foam beeing ripped off due to aerodynamic effects and turbulence or vibration, or due to boiling of trapped liquid nitrogen (condensated before flight out of air) are not influenced by the paint.
I think the paint was water resistant, and shielded rain etc. from the tank. But microscopic small cracks in the foam where not shielded by it. For that to work the paint must have been completely airtight, and elastic so that it does not get any pores or microcracks. I understand it that the air penetrates the foam through some pores or microcracks, and at the point near the metal surface of the tank where the temprature is below the dewpoint of nitrogen, the nitrogen in the air liquifies, and creates a very cold condensate. When the Shuttle starts, and ascends into the sky, the air pressure decreases along with the gained altitude. When the pressure is low enough for the liquid nitrogen-condensate to boil again, the nitrogen becomes a gas, expands, and blows the foam off. Like water that is trapped under concrete underneath a highway. When winter comes it freezes and expands, causing the concrete to break apart.  
The only way to make the foam less vunerable is to make it as airtight as possible. No microfractures, no trapped holes and bubbles etc. On some parts holes are drilled into the foam in a certain pattern, so that trapped nitrogen can expand out.
As far as I know the ET-foam structure did not benefit from the paint, and therefore it was not used on later missions.

If there was any coat on the Buran Tank, I do not know. Maybe they had some some special coating, but maybe they just painted the foam. If is was just paint than I would guess it was also there to protect against rain and snow and for cosmetics.
After all, 113 STS missions did not experience any critical damage due to foam shedding. One did.
The buran flew one test mission, so it would be very unlikely that this mission would suffer a foamshedding inflicted damage.

Offline Dogsbd

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RE: Buran and debris
« Reply #6 on: 11/03/2005 10:39 PM »
Was the Buran tank, or more correctly the Energia rocket, really coated externally with foam as the STS ET is?



Offline lmike

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RE: Buran and debris
« Reply #7 on: 11/03/2005 11:04 PM »
There were 6 missing tiles, some dents, and a slightly bent airframe in the tail section http://www.buran.ru/htm/flight.htm  http://www.buran.ru/htm/flight.htm * (excellent resource btw, but mostly in Russian)  But, apparently, they were all caused by the re-entry airdynamic, vibrational and thermal stresses.  

All that the memoirs of the lead designer (Gubanov) on the site say is that the second stage (the ET) was covered with “Polyurethane foam and an ablative” which was sprayed on.  Paint wouldn’t hold the (dangerous sized) foam chunks from falling as noted by another poster.  Also, as was noted 1 clean launch cannot be conclusive, although it doesn’t disprove that they may have developed a more capable compound.  Looking at the video the launch does look pretty clean.

*Doh!  The links are wrong, anyway scroll to the bottom and click on the last two text links for some photos of the post flight damage. (for the first flight, it's pretty minor)

Offline darkenfast

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RE: Buran and debris
« Reply #8 on: 11/04/2005 04:32 AM »
The amount and type of insulation might be different because the Buran/Energia, as I recall, used different propellants.  There was no liquid hydrogen, which is far more difficult to handle/store/insulate than LOX/RP-1.  Many rockets with LOX have no external insulation.

Offline lmike

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RE: Buran and debris
« Reply #9 on: 11/04/2005 04:49 PM »
The second stage (in Russian nomenclature) , similar to the STS ET+main engines, ran on liquid hydrogen+LOX.  LOX was in a conical tank at the top, and the LH2 in the cylindrical tank at the bottom.  ( see http://www.buran.ru/htm/rocrt2.htm ) The RD-0120 was the first Soviet high thrust LH2 engine.  In fact, creation of liquid hydrogen industry almost from scratch was one of the huge expenses of this project.  

The designer Gubanov specifically states the need for the foam (similar to the STS ET) "... it added a lot of weight, but that was the only way to prevent hydrogen evaporation during flight..."

From Wade: "Stage Number: 1. 1 x Energia Core Gross Mass: 905,000 kg. Empty Mass: 85,000 kg. Thrust (vac): 800,286 kgf. Isp: 453 sec. Burn time: 480 sec. Isp(sl): 354 sec. Diameter: 7.75 m. Span: 7.75 m. Length: 58.77 m. Propellants: Lox/LH2 No Engines: 4. RD-0120 Status: Out of Production. "

The side boosters were kerosene+LOX, and much lighter insulated.

Offline Rob in KC

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RE: Buran and debris
« Reply #10 on: 11/05/2005 12:42 AM »
Something tells me the Russians got it right with their booster. Looking at the pictures on the Buran thread it makes me wonder why the US didn't use the pause after STS-107 to evaluate using this for the last five years of operations.

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