Regarding high temp auto-pressurization: How thick does a layer of epoxy have to be to prevent reaction to LOx? Is a linerless tank simply lined with extra epoxy from the molding process?
My gut tells me that as a grotesque over-reaction to the foam strike on an RCC leading edge loss of a Shuttle, that NASA has baked into their requirements some quite unrealistic assumptions. Are the engineering justifications for that requirement as written available?
Are there any recorded birdstrikes in launch vehicle history?
How many launches have there been?
That said didn't Mercury and Gemini ride inside fairings.
Apollo had the "eyelid" due to concerns about exhaust from the emergency escape system motors cutting visibility after they fired on separation and covered the windows?
or detecting if the birds are flying above the launch pad and only launching if there is a clear path. One of the three has to be possible. I could see drones chasing birds away as one solution.
Quote from: tdperk on 08/15/2017 01:49 pmAre there any recorded birdstrikes in launch vehicle history?
Quote from: Jim on 08/17/2017 10:32 amQuote from: tdperk on 08/15/2017 01:49 pmAre there any recorded birdstrikes in launch vehicle history?[ duplicative video deleted ]Wow, I had not seen that before. I imagine the sound basically disabled them (full on panic), but they were dead anyway... The radiant heat of the SRB's would have fried them even if they tried to fly away at full speed.
Quote from: tdperk on 08/15/2017 01:49 pmAre there any recorded birdstrikes in launch vehicle history?[ duplicative video deleted ]
Still about, what, two seconds from launch it was doing 30mph? No visible change in the foam.
Quote from: tdperk on 08/17/2017 06:48 pmStill about, what, two seconds from launch it was doing 30mph? No visible change in the foam.That is Columbia type thinking.
Quote from: Jim on 08/17/2017 07:03 pmQuote from: tdperk on 08/17/2017 06:48 pmStill about, what, two seconds from launch it was doing 30mph? No visible change in the foam.That is Columbia type thinking.No, the Columbia type thinking is seeing damage and imagining it is not relevant, because it has not been yet.Observing that birdstrikes at that speed cause no damage is the beginning of an engineering assessment as to what is a hazard, putting a lower bound to the issue with respect to a structure which is no longer in use.
Quote from: tdperk on 08/17/2017 07:17 pmQuote from: Jim on 08/17/2017 07:03 pmQuote from: tdperk on 08/17/2017 06:48 pmStill about, what, two seconds from launch it was doing 30mph? No visible change in the foam.That is Columbia type thinking.No, the Columbia type thinking is seeing damage and imagining it is not relevant, because it has not been yet.Observing that birdstrikes at that speed cause no damage is the beginning of an engineering assessment as to what is a hazard, putting a lower bound to the issue with respect to a structure which is no longer in use.Just wrong. Columbia type thinking is seeing an impact and hand waving it away just as you did.
No, you are just wrong. The history of NASA's mismanagement of it's human spaceflight program is of seeing actual damage and ignoring it. Observing no damage is a very different thing.For O-rings to ice to presumably damage to tiles caused by shed foam, NASA ignored actual damage caused by it's piss poor engineering, and carried on as before in spite of that observed damage and the plausibility that the damage could be far worse later.Observing no damage /= observing damage.But imagining "no damage" = "damage"...that is the sort of paralysis by meaningless and endless analysis (and I mean that two ways, endless by being indefinite and endless by way of having no point) which will prevent NASA from getting anything done worthwhile if it is allowed to continue even if it is given twice it's current budget. You can always spend all the money and time you have making something metriclessly "more safe".And it may be "safe" for a government bureaucrat pretending to be an engineer to do just that, the Iron Laws of Bureaucracy being what they are.The fact a material as well characterized as the foam on the ET was, sustains no damage from a birdstrike at about 30mph provides good info as to what kind of hazard a birdstrike poses to a CF structure. Where is the evidence the birdstrike requirement spoken of in this thread is driven by engineering? What is that requirement, exactly?When arriving at it, did they remember to thaw the bird?
Quote from: tdperk on 08/17/2017 08:32 pmNo, you are just wrong. The history of NASA's mismanagement of it's human spaceflight program is of seeing actual damage and ignoring it. Observing no damage is a very different thing.For O-rings to ice to presumably damage to tiles caused by shed foam, NASA ignored actual damage caused by it's piss poor engineering, and carried on as before in spite of that observed damage and the plausibility that the damage could be far worse later.Observing no damage /= observing damage.But imagining "no damage" = "damage"...that is the sort of paralysis by meaningless and endless analysis (and I mean that two ways, endless by being indefinite and endless by way of having no point) which will prevent NASA from getting anything done worthwhile if it is allowed to continue even if it is given twice it's current budget. You can always spend all the money and time you have making something metriclessly "more safe".And it may be "safe" for a government bureaucrat pretending to be an engineer to do just that, the Iron Laws of Bureaucracy being what they are.The fact a material as well characterized as the foam on the ET was, sustains no damage from a birdstrike at about 30mph provides good info as to what kind of hazard a birdstrike poses to a CF structure. Where is the evidence the birdstrike requirement spoken of in this thread is driven by engineering? What is that requirement, exactly?When arriving at it, did they remember to thaw the bird?So you are concluding that bird strikes are safe for all vehicles from a single video where a bird strike did not do visually obvious damage to one vehicle. Right.
Columbia type thinking is seeing potential issues, but just handwaving them away because they happened before without any actual failure.
Quote from: Eric Hedman on 08/17/2017 05:41 am or detecting if the birds are flying above the launch pad and only launching if there is a clear path. One of the three has to be possible. I could see drones chasing birds away as one solution. https://www.nasa.gov/mission_pages/shuttle/behindscenes/avian_radar.html
<snip>The fact a material as well characterized as the foam on the ET was, <snip>
This has wandered away from the point of the tread. Which is how a carbon composite tank affects the payload and operations such as recovery of boosters. Bird strikes is not any more of a concern by a carbon composite tank than for other LV designs.
Most notable surprise-moments from shuttle:- When a seemingly "harmless" suitcase-sized piece of ET foam managed to put an 18" by 18" hole in an RCC panel during one of the CAIB tests. That result quite literally dropped the jaws on a boatload of engineers and management and proved to be the "smoking-gun" evidence for what happened to Columbia.- When the supposedly "fixed" foam-loss problem turned out to be very much NOT fixed on STS-114 (the first Return To Flight mission after Columbia). It initiated a "Take 2" on fixing the ET foam loss problem and yet another stand-down for the space shuttle.- Every monitored shuttle mission since STS-114 observed multiple instances of ET foam loss, despite the problem now supposedly having been fixed... Twice... Fortunately, most of those pieces were very small.
Do I infer correctly that if the radar spots the vultures just before launch that it is scrubbed? Or can the same radar target a focused sonic weapon, shotgun, etc? Do the environmental protections in place prohibit those?