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<ProjectThoth>
Question for the aero people - in the case of BFR, what exactly are the stubby delta wings supposed to do?
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<Bornholio>
they are only useful at hypersonic speeds , for roll stabity mostly, but some small cross range ability also, before it goes back to vertical mode
<Bornholio>
you can put them on rockets in KSP and try them out, work best with deployable control surfaces
<ProjectThoth>
Bornholio: Could you achieve the same thing with a boattail and body flaps?
<Bornholio>
they have windows they want to have at a particular facing
<ProjectThoth>
Assuming, well, that there were no windows.
<Bornholio>
so you make a bisymetric wing shape that has greater lift one direction than the other
<ProjectThoth>
Ahh.
<ProjectThoth>
Bornholio: See, I'd imagine that the wings would screw up the center of mass and make landing a pain in the ass.
<Bornholio>
yes, but they are transonic and rear facing at that point, so they are no worst than big floppy landing gear at that point
<ProjectThoth>
So the wings aren't that heavy, then?
<Bornholio>
by volume i'd gues no worse than the rest of the craft. probably tucking a few oddly shaped things in them
<Bornholio>
but none of the cutaways released show anything
<ProjectThoth>
Hmm, I thought it was going to be an issue... I was thinking that a squared-circle shaped boattail would be able to give body flaps a good mounting surface while not being horribly imbalanced in terms of mass.
<Bornholio>
honestly look at any of the lifting body craft and you will see the same
<ProjectThoth>
Yeah, I see what you mean.
<Bornholio>
like the x-38
<Bornholio>
I get to fondle that one every once in a while
<wb99999999>
hey born
<Qboid>
wb99999999: stratochief left a message for you in #RO [29.12.2017 15:18:56]: "a J-2 has a low combustion pressure, so I think it would suck at sea level. I've used the HG-3 as a sea level J-2 version, though. that was the development engine between J-2 and RS-25, I think."
<Bornholio>
hi 9's
<wb99999999>
okay...that's what I am about to talk about
<wb99999999>
do you think we should config J-2-SL?
<ProjectThoth>
Bornholio: Well, if they're not that heavy, and they're not a thermal nightmare on reentry, then I guess there's no need for a square boattail.
<Bornholio>
it was just a proposal, never run tested, but still maybe worth it as a pack
<wb99999999>
we had HG-3 now, you know
<Bornholio>
J-2 aerospike is a better one, it was run tested
<wb99999999>
but it has no TVC...
<wb99999999>
it's a bit blurry now where the line lies
<Bornholio>
I'd say if M-1 is on the list, then so should J-2T-200/250, J-2S and HG-3 plus both SL version
<wb99999999>
this is my problem...then so should STME, which is something I actually wanted to see
<wb99999999>
and we're into full-on notional territories
<wb99999999>
maybe if something hasn't been built, but something courtesy to its idea and/or technology has been, it is okay?
<Bornholio>
I only added NTR Rockets that had real test runs, so i do agree that notionals should be set apart
<Bornholio>
I probably should not have included SNTP since it never had a full assembly test
<Bornholio>
but then again we have NERVA's and BNTR which are just paper designs
<wb99999999>
you see STME is more than just a proposal...if we're going with the same logic of having HG-3 (for it is the basis of the RS-25), then we should totally have STME, which is the basis of RS-68
<Bornholio>
even given that the real Rover engines were better than NERVA's
<wb99999999>
NERVA is... kind of a mascot of KSP now
<Bornholio>
Unfortunaley with stats that are guesses from '62 instead of knowns from '72
<wb99999999>
it is unfortunate
<wb99999999>
out of every tested NTR Squad chose to base their nuke upon the one that is not built...
<wb99999999>
but nowadays that bell-shaped nuke is so ingrained in KSP players
<Bornholio>
well the SNTP looks very like it if you add a ginormous extension
<wb99999999>
the naming scheme tho
<Bornholio>
Pewee is awesome
<wb99999999>
try say that in a lecture room full of senior scholars
<ProjectThoth>
I'm disappointed that the stock NTR is so weak... and also that LANTR isn't a stock part.
<wb99999999>
I'd say the stock NTR is pretty well-balanced
<Bornholio>
yes for kerbal it is
<wb99999999>
it is weak, but it also runs on VERY dense juice
<ProjectThoth>
See: The Duna expedition that I'm in the middle of working on, that requires no fewer than 18 NTRs to actually get a useful TWR.
<Bornholio>
its ISP is a bit high
<ProjectThoth>
wb99999999: Meh, fair point.
<ProjectThoth>
Still, LANTR.
<wb99999999>
at this point you'd as well go for that 3.75m vacuum engine, of which I forgot the name of.
<wb99999999>
that one has one of the highest TWR in the stock parts
<wb99999999>
actually I've been thinking about the lack of a demand for NTRs in RO
<wb99999999>
and came to the conclusion that the reason is the hydrolox engines
<ProjectThoth>
NTRs are only really useful if you're dealing with battleship-sized Mars missions.
<wb99999999>
in 90% of the cases hydrolox is cheaper and less bulky
<Bornholio>
well it turns out if you have no gravity, artifical or other iwse going to mars is bad, also , any hydrolox timed mission will mean that an old male astronaut will be the only person who can go because radiation levels will be too high
<ProjectThoth>
Tumbling pigeon + NTRs.
<wb99999999>
I see your point
<Bornholio>
my one big disagree with BFR is that its not going to be able to take humans for those considerations
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<ProjectThoth>
Bornholio: Oh, I just think BFR is too damn big.
<Bornholio>
nah, real mars missions need big, ithink it will haul the ISRU and other cargo for manned missions
<ProjectThoth>
I'm interested in the aerodynamics because I'm starting to accept the feasibility of a high-altitude/speed flip.
<ProjectThoth>
(for reusable rockets, ofc)
<Bornholio>
Nice thing about nukes for that purpose is that alternate fuels are really easy (unless add oxygen)
<ProjectThoth>
I still don't quite get how DC-X was supposed to survive reentry, going in nose-first and all that.
<Bornholio>
like a nuclear bomb
<Bornholio>
chines for roll stabity
<Bornholio>
low of -21F burr sounds like kerbals will risk life and limb at that time
<ProjectThoth>
Bornholio: TPS must have been a nightmare.
<ProjectThoth>
I cannot conceive of a good solution for something like that. Active cooling, maybe?
<Bornholio>
High G/ Heat Sinking
<Bornholio>
lower total heat load with higher peak
<Bornholio>
opposite of space shuttle
<ProjectThoth>
Would've been interesting.
<wb99999999>
aka the thing you do when you have to emergency return a capsule
<wb99999999>
ballistic reentry and ditch the heatshield before the heat conduct
<wb99999999>
well I am talking about a capsule after all
<ProjectThoth>
wb99999999: DC-X was supposed to come in nose-first.
<wb99999999>
why does wikipedia has a picture of that engine firing?
<wb99999999>
what?
<ProjectThoth>
First time I've seen radiative cooling and active cooling combined into one system... actually reminds me of a thought I had about improving the performance of ablative heat shields with an actively-cooled backplate.
<ProjectThoth>
wb99999999: They might have done a powerhead test?
<ProjectThoth>
Because I don't think the SSME was ever tested horizontally... and I doubt STME would have been, either.
<wb99999999>
it's dense enough, but its chemistry simple enough
<ProjectThoth>
Going off of my memory of Ignition!, methane development in the US was abandoned early because it had about the same performance as RP-1 with a crappier density/all-cryogenic propellants.
<wb99999999>
you know what Born
<wb99999999>
fueling the venture star with metholox might actually made it work
<wb99999999>
less tankage, far less insulation, easier manufacture
<ProjectThoth>
wb99999999: If you can magic your way around the tanks...
<Bornholio>
only reason it didn't fly was stupid demand for composite tanks
<ProjectThoth>
I know that Gary Hudson is a huge methalox advocate, but that's where he and I disagree.
<ProjectThoth>
(and composite tanks, too)
<wb99999999>
yes, and that dumb tank can be simplified if you need less of it and less complex construction at the same time
<Bornholio>
hydrolox dreams and PBAN nightmares have a good night
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<ProjectThoth>
wb99999999: I guess. I don't like funky tank shapes.
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<ProjectThoth>
See: why my favorite solution for stage recovery is currently something like BFR/Constellation's Mars landers.
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<ProjectThoth>
Sadly, I pitched the Constellation aeroshell data I used to have because I abandoned my original investigations of it about a year ago.
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<ProjectThoth>
I really don't like the winglets.
<stewartx_>
what did they do to you?
<ProjectThoth>
stewartx_: Killed my family.
<ProjectThoth>
stewartx_: More seriously, I'm talking about BFR's little wing nubbins and wondering if they could be replaced with a boattail.
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<Starwaster>
projectthoth split body flap
<ProjectThoth>
Starwaster: Yeah, that's what I'm thinking of.
<ProjectThoth>
Square boattail + flaps.
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<ProjectThoth>
What's the technical shape of Falcon 9's payload fairing?
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<wb99999999>
!tell ProjectThoth the shape of falcon 9's fairing is called a cone-egg, according to what the same shape is called in the fairing mod
<Qboid>
wb99999999: I'll redirect this as soon as they are around.
<ProjectThoth>
wb99999999: Too late, I died.
<Qboid>
ProjectThoth: wb99999999 left a message for you in #RO [30.12.2017 08:52:22]: "the shape of falcon 9's fairing is called a cone-egg, according to what the same shape is called in the fairing mod"
<wb99999999>
what
<wb99999999>
hmm, I have a gravity loss of about 1.4 km/s
<wb99999999>
is this a good launch or a bad one?
<ProjectThoth>
I dunno, did you make it?
<wb99999999>
yeah of course
<wb99999999>
I meant when I finished insertion
<wb99999999>
when I reached orbit I had a total of about 1.43 km/s of gravity loss
<wb99999999>
launched by manual piloting so I want to see if my skill still hold up
<wb99999999>
okay, I guess this is a pretty good number then
<wb99999999>
I launched it again, and get a very similar number
<wb99999999>
consistency is good
<ProjectThoth>
\o/
<wb99999999>
actually I am very proud of having the useless skill of manually launching rocket in RO
<soundnfury>
:)
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<Probus>
If you make the same rocket over and over, isn't KCT supposed to decrease the build time?
<Probus>
IRL, the first 3 or so of a project are the real time consumers.
<Probus>
Well, at least for the designs I work on.
<soundnfury>
Probus: only in stock I think, not with rp0's KCT config
<soundnfury>
also it might do it by parts and we're proc part heavy :/
<Probus>
Ah, that's true.
<Probus>
We probably shouldn't have the option for Kevlar parachutes right from the start.
<Probus>
I wonder what material was used back then for heavy duty chutes.
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<ProjectThoth>
I would guess silk or nylon.
<ProjectThoth>
Possibly canvas?
<Probus>
I wonder if they even had nylon.
<Probus>
I bet you're right ProjectThoth. I bet it was canvas.
<soundnfury>
nylon was used for parachutes in WWII
<ProjectThoth>
Yeah, canvas sounds about right.
<ProjectThoth>
Yup, that's why there was a stocking shortage.
<soundnfury>
so by 1951 they _totally_ have it.
<ProjectThoth>
I think Dacron was invented as an artificial silk.
<Probus>
Spot on ProjectThoth and by 1951 they had it for sure
<Probus>
1965 for Kevlar
<ProjectThoth>
Useless trivia of the day: Kevlar is bulletproof, but not stab-proof in the slightest.
<ProjectThoth>
Reason is that bullets are blunt, so when they hit a Kevlar sheet, the force of impact is spread out across many fibers. Knives go straight through the weave.
<Probus>
I've also heard that police officers are taught not to stand sideways in a gun fight so that their vests have a better chance of catching the bullet.
<ProjectThoth>
And getting shot still sucks, you'll either get a big ol' bruise or you'll break a rib.
<ProjectThoth>
But, hey, I'll take broken rib over dead.
<Probus>
Yessir
<ProjectThoth>
I did a project in school that involved making Kevlar stab-proof.
<Probus>
That sounds interesting
<ProjectThoth>
We - I worked with a couple people - actually were pretty successful on that front.
<ProjectThoth>
But I decided to develop heat shields after that.
<Probus>
How did you do it?
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<ProjectThoth>
Drop tower and different materials... I think honey was the most successful.
<ProjectThoth>
Oh, or the heat shields?
<Probus>
Kevlar
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<BadRocketsCo>
*sigh*
<BadRocketsCo>
Corrupted save file
<wb99999999>
why it is not stab-proof...I mean at least somewhat resistant to a blade?
<wb99999999>
even plain clothing can stop a blade if it comes in at a bad angle
<ProjectThoth>
wb99999999: Goes right between the weave of the fabric.
<wb99999999>
oh I see
<Probus>
"the slow blade penetrates the shield"
<ProjectThoth>
Probus: Yeah, honey and a few springy p o l y m e r b o i s were the most successful.
<wb99999999>
you're essentially making a composite body armor then
<Probus>
Why honey?
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<Probus>
silk is supposed to be good against arrows. I wonder if it would be any good against knives.
<ProjectThoth>
Probus: Partner's idea.
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<Bornholio>
what module sets control tonnage for avioics/
<Bornholio>
?
<Bornholio>
eh nm its ModuleAvionics
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<Bornholio>
5 attempts, fixed pressurized tank problem on 3rd stage, hot start center a-4 just before booster sep, needs just a tad more nitrogen for ullage, target 170x170, final 166x158km
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<stratochief>
noice. nitrogen ullage seems sad, though. I'm usually a hot stager :P
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<Bornholio>
needed some coast
egg|anbo|egg is now known as egg
<stratochief>
fair enough. I'm an irrational fan of solids for ullage
<Bornholio>
too many tiny rockets and asymetrical thrust losses adding up. Def a couple of techs later and after i've got full data on them
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<lamont_>
bornholio: only 8000 dV?
<Bornholio>
nope had to push it up
<Bornholio>
how do i know early that i'm not gonna make it?
<lamont_>
kinda don’t
<lamont_>
if phi never falls below 45.0 you’re not going to space
<lamont_>
which should happen booster-sep-ish
<Bornholio>
no phi till booster phase end?
<Bornholio>
or plastered at 45
<lamont_>
clipped to 45.0
<lamont_>
the thrust integral expansion is only valid around +/- 45 degrees, so there’s a cutoff that clips it so it always converges — but when it clips then the predicted cutoff position will not equal the desired cutoff prediction
<lamont_>
the two debug lines downrange of you which are tangent to your desired orbit are at rp (predicted location) and rd (desired location)
<lamont_>
if phi is clipping at 45.0 then those will not be on top of each other, and rp may be below sea level, and the difference between them is the rbias term
<Bornholio>
hmm
<lamont_>
once it stops clipping rp = rd and rbias = 0,0,0
<lamont_>
also at tgo < 40 seconds it actually sets rd = rp and rbias goes to zero and it releases the position constraint (or else it all goes wobbly)
<lamont_>
if you havent seen phi < 45 before tgo < 40 then it’ll be wildly off
<lamont_>
and yeah i don’t know how to translate that into actually useful feedback to the user
<Bornholio>
so its not simple like Vg0<total dV remaining
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<wb99999999>
aye
<Bornholio>
I broke my million dolar solar cell. :( Comsat one down the toilet
<wb99999999>
I discovered that you can potentially use and vernier engine with any main engine
<wb99999999>
just have a separate tank and fill it with the right juice
<wb99999999>
and adjust the burn time so it matches the main engine
<Bornholio>
what i'm not spose to use lr101's are main thrid stage engines?