And a fine piece of journalism it is, sir.I doff my hat in your general direction (I would hit your tip jar, if you had one).
Did I understand correctly that they are removing (some of) the brick from the trench or just the old flame deflector?
Still hard to image any rocket engines generating as much blast force as five F-1s.
Quote from: AS_501 on 02/06/2015 05:34 pm Still hard to image any rocket engines generating as much blast force as five F-1s.One 5 segment SRB is more than 2 F-1s and has a more blast force during ignition. Much easier to build flame deflector for F-1s than SRB's
To answer spacenut's and Halidon's queries, as well as follow-on to AS_501 and Jim, the trench and deflector is being fabricated to specs for "advanced boosters"--that is, fiber wound case (FWC) units that have even higher over-pressure than the 5-segs (which are much higher than even the "tuned up" 4-seg boosters used on STS-124). It should be noted that the F-1s ramped up in thrust (and acoustical energy) over a number of seconds, while the SRBs exert a massive amount of OP at ignition (see transient overpressure vs MEOP [Mean Effective Operating Pressure]).One of the coating materials used in lieu of the old bricks to withstand the OP and heat is "fondue fyre". I can't imagine another rocket that will create the same sonic, thermal and OP as the notional FWC, or even the 5 segs, but we'll see (at least from 39B, a-hem). Any other rocket that flies from 39B would only be constrained by orientation, not output.I'm still of a mind the first launch of SLS (should it actually come to pass) will prove to be a learning experience re: pad substrate, structure and MLP/LUT.
Fascinating perspectives, thanks. Probably a silly point here, but I wonder if there would be any value in staging some trench materials behind an SRB test motor in Utah, without compromising SRB test objectives. Also, any indication if they will conduct an FRF on the first SLS?
Interesting, thanks. Do SRBs create a "sand-blasting" effect (from any un-burnt propellent?) on the trench that liquid engines do not?
Not just unburnt but the primary fuel is aluminum, so it is very corrosive.
That would be splitting hairs.
Exhaust will not be split. All to the north.
Quote from: newpylong on 02/06/2015 08:08 pmExhaust will not be split. All to the north.Wasn't Saturn V's exhaust split? I'd assume so as 39A and B were built with both north and south flame duts. If so, why wouldn't SLS's be split too then?
Note newlylong's response was re: SRB exhaust only per the context. I expect the RS-25 exhaust will be directed S (same as it was for STS). The geometry of the RS-25s might mean something different (a split of 2x2 N/S) but expect it to mimic STS.
No, all of the exhaust is going to the north, SRBs and RS-25s. No more wedge.
Quote from: PahTo on 02/09/2015 10:08 pmNote newlylong's response was re: SRB exhaust only per the context. I expect the RS-25 exhaust will be directed S (same as it was for STS). The geometry of the RS-25s might mean something different (a split of 2x2 N/S) but expect it to mimic STS.STS was split because of the sidemount
Following simulations using NASA Ames’ supercomputer, a deflector design – that could withstand the high heat from plume exhaust, that did not result in plume blow-back, and whose surface pressure was within design margin limits – was selected.
Quote from: Jim on 02/10/2015 12:05 amQuote from: PahTo on 02/09/2015 10:08 pmNote newlylong's response was re: SRB exhaust only per the context. I expect the RS-25 exhaust will be directed S (same as it was for STS). The geometry of the RS-25s might mean something different (a split of 2x2 N/S) but expect it to mimic STS.STS was split because of the sidemountTo be accurate, Saturn V used wedge-shaped flame-deflector as well. It was mobile, on rails as it wasn't tied into the pad's water deluge system like the STS flame deflector.
Quote from: DaveS on 02/10/2015 03:26 pmQuote from: Jim on 02/10/2015 12:05 amQuote from: PahTo on 02/09/2015 10:08 pmNote newlylong's response was re: SRB exhaust only per the context. I expect the RS-25 exhaust will be directed S (same as it was for STS). The geometry of the RS-25s might mean something different (a split of 2x2 N/S) but expect it to mimic STS.STS was split because of the sidemountTo be accurate, Saturn V used wedge-shaped flame-deflector as well. It was mobile, on rails as it wasn't tied into the pad's water deluge system like the STS flame deflector.But was Saturn's flame divided? It sure looks like it was in this picture. And if so, why won't SLS's be divided? It has all of it's exhaust in one central area like Saturn V, not offset like STS. And it will be about 1Mlbs more thrust at liftoff that Saturn V I'd always assumed 39A and 39B were set up the way they were because Saturn V had too much thrust to direct out just one flame port. N-1's pad was built with 3 flame ducts...I assumed for the same reason. But if SLS's thrust can all go out the north side, seems like that was an incorrect assumption. Why build the pad with two flame ducts then rather than just one if one can do the job?
I'm no engineer, but there is something inherently unsettling about deflecting all that energy in one direction (asymmetrically). Perhaps this could damage the launch platform?
Stop the nonsense. Nothing is going to be damaged and there is nothing inherently bad with a unidirectional flame.Simulations and testing to aid in design for things like this did not exist when Saturn and even STS were developed. The single trench is less complex, allows for easier inspection and will be cheaper to build.
Thanks all for the feedback. While we're in the general area of the trench, it will be interesting to see how the SLS sound suppression water system will be configured, given that:- SLS will be generating more acoustic energy that STS (I assume)- The spacecraft is at the top of the stack and inside a shroud, not down on the side and exposed
Quote from: newpylong on 02/11/2015 04:42 pmStop the nonsense. Nothing is going to be damaged and there is nothing inherently bad with a unidirectional flame.Simulations and testing to aid in design for things like this did not exist when Saturn and even STS were developed. The single trench is less complex, allows for easier inspection and will be cheaper to build.Yes, but we're talking a pad that's already built, not a new one they are going to build. And the way it's built is to allow for exhaust out two sides especially with use of the Saturn type MLP's as SLS will. Is it just today they are able to to in depth analysis of construction and determine that 39B was so over built that it can handle almost 9Mlbs of thrust out either side? Something they'd couldn't be certain of in the 60's so they just added a lot of margin? Or something else?I'm still trying to get the "why" of only using one side of an existing pad that already has two flame ports. I understand the "why" of a new pad to only have one port with cost and simplicity.
Quote from: Lobo on 02/11/2015 05:02 pmQuote from: newpylong on 02/11/2015 04:42 pmStop the nonsense. Nothing is going to be damaged and there is nothing inherently bad with a unidirectional flame.Simulations and testing to aid in design for things like this did not exist when Saturn and even STS were developed. The single trench is less complex, allows for easier inspection and will be cheaper to build.Yes, but we're talking a pad that's already built, not a new one they are going to build. And the way it's built is to allow for exhaust out two sides especially with use of the Saturn type MLP's as SLS will. Is it just today they are able to to in depth analysis of construction and determine that 39B was so over built that it can handle almost 9Mlbs of thrust out either side? Something they'd couldn't be certain of in the 60's so they just added a lot of margin? Or something else?I'm still trying to get the "why" of only using one side of an existing pad that already has two flame ports. I understand the "why" of a new pad to only have one port with cost and simplicity.I answered your questions already as to why. Just because there are two it doesn't mean you need to use both.If you need further information I am sure it's out there direct from GSDO.
Quote from: newpylong on 02/11/2015 06:51 pmQuote from: Lobo on 02/11/2015 05:02 pmQuote from: newpylong on 02/11/2015 04:42 pmStop the nonsense. Nothing is going to be damaged and there is nothing inherently bad with a unidirectional flame.Simulations and testing to aid in design for things like this did not exist when Saturn and even STS were developed. The single trench is less complex, allows for easier inspection and will be cheaper to build.Yes, but we're talking a pad that's already built, not a new one they are going to build. And the way it's built is to allow for exhaust out two sides especially with use of the Saturn type MLP's as SLS will. Is it just today they are able to to in depth analysis of construction and determine that 39B was so over built that it can handle almost 9Mlbs of thrust out either side? Something they'd couldn't be certain of in the 60's so they just added a lot of margin? Or something else?I'm still trying to get the "why" of only using one side of an existing pad that already has two flame ports. I understand the "why" of a new pad to only have one port with cost and simplicity.I answered your questions already as to why. Just because there are two it doesn't mean you need to use both.If you need further information I am sure it's out there direct from GSDO.Having a single side flame deflector means that there is no leading edge that has to take the brunt of the exhaust.
Quote from: Jim on 02/11/2015 07:04 pmQuote from: newpylong on 02/11/2015 06:51 pmQuote from: Lobo on 02/11/2015 05:02 pmQuote from: newpylong on 02/11/2015 04:42 pmStop the nonsense. Nothing is going to be damaged and there is nothing inherently bad with a unidirectional flame.Simulations and testing to aid in design for things like this did not exist when Saturn and even STS were developed. The single trench is less complex, allows for easier inspection and will be cheaper to build.Yes, but we're talking a pad that's already built, not a new one they are going to build. And the way it's built is to allow for exhaust out two sides especially with use of the Saturn type MLP's as SLS will. Is it just today they are able to to in depth analysis of construction and determine that 39B was so over built that it can handle almost 9Mlbs of thrust out either side? Something they'd couldn't be certain of in the 60's so they just added a lot of margin? Or something else?I'm still trying to get the "why" of only using one side of an existing pad that already has two flame ports. I understand the "why" of a new pad to only have one port with cost and simplicity.I answered your questions already as to why. Just because there are two it doesn't mean you need to use both.If you need further information I am sure it's out there direct from GSDO.Having a single side flame deflector means that there is no leading edge that has to take the brunt of the exhaust.And that certainly makes sense as well.Why did Saturn V divide it's thrust then rather than just have it all go out the north as well?
That's my guess, but I was hoping for someone who knew the real reason Saturn V was divided while SLS will not be, even thought Saturn V had less thrust than SLS will, could explain fully.
Quote from: Lobo on 02/16/2015 05:05 pmThat's my guess, but I was hoping for someone who knew the real reason Saturn V was divided while SLS will not be, even thought Saturn V had less thrust than SLS will, could explain fully.According to:http://www.hq.nasa.gov/pao/History/SP-4204/ch11-7.htmla two-sided deflector was selected for LC 39 because that was what had been used at LC 34 and LC 37.According to:http://www.hq.nasa.gov/pao/History/SP-4204/ch2-4.htmla two-sided deflector was chosen for LC 34 because the four-sided deflector design previously used by ABMA/MSFC for Redstone and Jupiter would have created plumes that would have blocked views from the blockhouse. This was an uncooled design. Single-direction deflectors were used on Saturn test stands at MSFC and MTF, but they needed to be water-cooled and also required the pedestal to be taller, raising costs.Presumably, flame trench science has advanced since the early 1960s, especially as it relates to the use of acoustic suppression deluge systems. - Ed Kyle
Upgrades and modifications continue to the flame trench at Launch Pad 39B at NASA’s Kennedy Space Center in Florida. Pad B is being refurbished to support the launch of NASA’s Space Launch System rocket. The Ground Systems Development and Operations (GSDO) Program at Kennedy is helping transform the space center into a multi-user spaceport and prepare for Exploration Mission-1, deep-space missions, and the journey to Mars. For more information about GSDO, visit: www.nasa.gov/groundsystems. Photo credit: NASA/Kim Shiflett
I thought they were done with the flame trench wall upgrades, but in the last image we see a closeup of the south end, which looks in pretty bad condition. (Wall cracks, weeds, etc) Are they only doing the northern end?