<wb99999999>
well better than liquid oxygen right...
<ProjectThoth>
I mean, hydrogen peroxide would be nice, I think it's a criminally underused oxidizer.
<wb99999999>
liquid oxygen is just a fire hazard...
<soundnfury>
peroxide would be my choice, but the rest of CUSF are scared even of that
<ProjectThoth>
Plus, I can make the jetpack nerd happy.
<wb99999999>
peroxide is probably the best thogh
<soundnfury>
I like peroxide, but the question is always what to burn with it.
<soundnfury>
(My suggestion of tetrahydrofuran was not well received ;)
<ProjectThoth>
Well, there's the ARCA nutters, they're trying to use RP-1.
<Bornholio>
getting high enough purity htp is hard, and solids easy, you can even start with candy rockets and still get high enough to need specialized launch venues without silly liquid problems
<soundnfury>
Bornholio: only need htp if you want to drive pumps with it
<wb99999999>
yep
<soundnfury>
otherwise you can make do with something below the critical 70-ish%, which is also less dangerous
<wb99999999>
liquid is just so much harder
<ProjectThoth>
It's somewhat straightforward to concentrate to near-70%, iirc.
<wb99999999>
the amount of math...
<ProjectThoth>
Yeah, the competition we're trying to get involved in has three categories: Off-the-shelf solid, in-house solid, and hybrid.
<ProjectThoth>
I lean very hard in the direction of "hybrid" because I don't see how we can get a leg up with the other two.
<wb99999999>
also I have no idea on how to build an actual liquid rocket even with the engine in place
<wb99999999>
solid rocket is just a tube and propellant stuffed in it
<wb99999999>
but liquid rocket is some other story...
<ProjectThoth>
I currently favor LOX/paraffin, not sure what CUSF was/is using.
<wb99999999>
like, you need to have tanks...
<wb99999999>
in a fuselage that's aerodynamic but also strong enough...
<wb99999999>
just no
<wb99999999>
it's too hard...
<ProjectThoth>
I mean, in the grand scheme of things, solids have the same problem.
<wb99999999>
you don't need tanks, especially not separate ones for a solid
<wb99999999>
no worry about feeding
<ProjectThoth>
It's a worthy challenge.
<wb99999999>
that's why I used the word "fuselage" since it's no longer a simple casing, but a fully fledged container
<wb99999999>
I have a secret fear of propellant tanks in a makeshift liquid rocket just collapse and went up in a fireball due to stress
<wb99999999>
for me personally liquid rocket is just orders of magnitude more complex
<ProjectThoth>
soundnfury: So, let me guess, they went with hybrid because they drank the Kool-Aid on how safe they are?
<soundnfury>
ProjectThoth: to an extent. Also, they'd already started their hybrid when I first met them
<ProjectThoth>
Oh, lame.
<soundnfury>
and they thought it would be easy, and they've made no progress in the two years since I wrote that
<ProjectThoth>
soundnfury: To be fair, I think the only advantage of a hybrid is that it's something the uni would actually let us do.
<soundnfury>
all they've managed to get out of their hybrid is non-choked exhaust full of glowing unburned grains of sugar
<ProjectThoth>
Interesting thing about reciprocating pumps. Isn't that what XCOR was planning on using?
<soundnfury>
(did I mention they're using sugar/N₂O)
<ProjectThoth>
Oh, good god, why?
<wb99999999>
ratio?
<soundnfury>
they think it's safer
<ProjectThoth>
NO NO NO NO NO >__<
<wb99999999>
sugar is not safer
<wb99999999>
it is not...
<soundnfury>
in fairness, they have since switched to some sort of plastic/rubber/thing iirc
<ProjectThoth>
I had to argue against N2O pretty hard.
<ProjectThoth>
My preferred blend is LOX (or H2O2)/paraffin + iron oxide.
<ProjectThoth>
I think that's a decent compromise (and, again, one the uni will actually let us do).
<wb99999999>
wow...
<ProjectThoth>
But liquid would be nice.
<soundnfury>
iron oxide? what/why?
<soundnfury>
s/y?/y‽
<Qboid>
soundnfury meant to say: y‽iron oxide? what/why?
<soundnfury>
damn, regex'd :(
<ProjectThoth>
soundnfury: I might be misremembering from the last time I dealt with motors (about three years ago), but isn't that an additive for increasing thrust?
<ProjectThoth>
And the moment I say that, I realize how retarded I am.
<ProjectThoth>
Aluminum's the fuel, Thoth, not iron oxide.
<soundnfury>
it's already oxidised...
<soundnfury>
Al makes more sense, yeay
<ProjectThoth>
Aluminum burns. >__<
<soundnfury>
ProjectThermite
<wb99999999>
I think if you can get Aluminum working
<ProjectThoth>
But, yeah, additives are something I feel that's worth exploring.
<Bornholio>
FeOx is a good ISP adder for sugar rockets as is FeOx and Al mix
<ProjectThoth>
soundnfury: Yup, tried to make that once, too. :P
<wb99999999>
why just get some very powerful oxdizer and make a VERY powerful solid?
<ProjectThoth>
I only failed because I didn't have a ball mill.
<wb99999999>
aluminum as a fuel is quite a punch
<ProjectThoth>
I mean, I have to sell this somehow.
<ProjectThoth>
I kinda like peroxide/kerosene, if we had the option to do liquids.
<wb99999999>
I am worried about clogging with kerosene
<wb99999999>
would diesel or gasoline work? I mean I know gasoline is kinda dangerous
<ProjectThoth>
If only we could do propane!
<wb99999999>
isn't propane technically a cryogen?
<soundnfury>
straight CHn is often ill-behaved past the lowest molecular weights. Propane could work, but not octane
<soundnfury>
wb99999999: you can cool it for density / lower vapour pressure, but for a ground test you don't have too
<ProjectThoth>
Pintle injectors, yes or no?
<soundnfury>
hell yes
<wb99999999>
wait, so you can keep it liquid without pressurizing it?
<wb99999999>
or you just pressurize it anyway?
<soundnfury>
wb99999999: needs pressure for liquid at RT
<wb99999999>
it seems to me a propane tank isn't going to fly very well...
<ProjectThoth>
Is nitrogen a bad pressuring gas? Assuming a heat exchanger.
<soundnfury>
wb99999999: sure, not flight-weight
<wb99999999>
that's what I mean by "technically cryogen"
<soundnfury>
but you can worry about liquefying the fuel once you've got the basics working on ground tests
<soundnfury>
well, maybe "very soft cryogen"
<wb99999999>
for it to fly you kinda need to cool it down
<soundnfury>
it's not gonna cause e.g. liquid air to drip off your pipes
<wb99999999>
liquid air sounds very scary for some reason
<wb99999999>
maybe it is
<soundnfury>
liquid air is a good way to cause accidental kabooms :(
<wb99999999>
yep, my fear was rational after all lol
<soundnfury>
btw, beware: commercial "Propane" is usually a mixture of alkanes depending on local climate, blended to have a suitable vapour pressure at typical temperatures
<soundnfury>
e.g. in warm climates it may be mostly butane
<ProjectThoth>
Is helium better?
<ProjectThoth>
soundnfury: Noted.
<wb99999999>
isn't helium expensive?
<ProjectThoth>
Right, which is why I was wondering if nitrogen was an OK option.
<soundnfury>
ProjectThoth: I think nitrogen is fine for pressurisation, though it depends what it's in the tank with (i.e. temperature)
<soundnfury>
but self-pressurisation is much nicer if you can do it
<ProjectThoth>
Pressurizing the peroxide tank.
<wb99999999>
so I checked propane
<soundnfury>
ProjectThoth: ah, right
<ProjectThoth>
Unless it's possible to self-pressurize.
<ProjectThoth>
But no HTP, so.
<wb99999999>
it supposedly have a lighter molecular weight than kerosene and the like?
<wb99999999>
correct me if I got it wrong
<soundnfury>
ProjectThoth: nah, the only thing perox could self-pressurise under is the O₂ from decomposition, and that's a hairy proposition
<ProjectThoth>
soundnfury: Yeah, that could be hairy.
<soundnfury>
wb99999999: yeah, propane is C₃H₈
<ProjectThoth>
I'm thinking of a graphite nozzle and using graphite steering vanes.
<wb99999999>
so it in theory should have a better Isp...except we don't know our oxidizer yet
<wb99999999>
I have a crude idea
<wb99999999>
if you're launching your liquid through the atmosphere
<wb99999999>
why not make the nozzle air-cooled?
<ProjectThoth>
soundnfury: Oh, what'd you consider for ignition? I'm, stupidly, partial to the Russian method.
<wb99999999>
don't know if this will work or not
<soundnfury>
ProjectThoth: my baseline idea was e-match to light off some Mg under a slow-flow of oxidiser
<ProjectThoth>
That is exactly what I was thinking.
<ProjectThoth>
(the Russians use a remote-controlled match, basically)
<wb99999999>
what if we have an air ram or something and we vent the air through the nozzle to cool it
<ProjectThoth>
Well, considering the nitrogen exchanger...
<wb99999999>
oh, okay
<wb99999999>
then this is redundant
<ProjectThoth>
But I prefer graphite and ablative, generally speaking.
<wb99999999>
if you can get ablative going that'd be perfect
<wb99999999>
it's the preferred method after all
<ProjectThoth>
Fortunately, I have a trick up my sleeve that won a science fair...
<ProjectThoth>
I think with some adaptation, I could probably get it to handle the temps we're talking about here.
<ProjectThoth>
Or, well, wood. :P
<wb99999999>
it's the Chinese wooden heat shield all over again \o/
<wb99999999>
but yes, I've heard about wood charring and ablating away under heat
<soundnfury>
ProjectThoth: umm, did you see the design study at the end of my paper?
<ProjectThoth>
It's not the worst of ideas, I would trust my life to an oak heat shield.
<ProjectThoth>
soundnfury: Still reading it.
<soundnfury>
*cough* wood.
<ProjectThoth>
soundnfury: THE POWA OF COPPA
* soundnfury
raises an eyebrow
<ProjectThoth>
Shitty reference to a stupid joke, I'll get the link.
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<schnobs>
o/
<Maxsimal|Work>
Pap: Sorry I was afk in a long-ass meeting anyway, glad to hear from you. I feel like we need to get momentum back. Did you get many replies on that form you created for mission costs? I got sick of failing at contracts so I'm gonna look at cost balance a bit this weekend.
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<Maxsimal>
Anyone know which mod(s) might contain a gemini capsule compatible with RP0?
<schnobs>
FASA used to have a very fine one. If it's no longer compatile, though....
<schnobs>
(I honestly don't know)
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<wb99999999>
morning
<awang>
!tell riocrokite You're a lifesaver!
<Qboid>
awang: I'll redirect this as soon as they are around.
<awang>
Does anyone know of any parts that have a "proper" airfoil shape?
<awang>
Realized a bit ago that pretty much all the wings I've seen are flat slabs, so all the lift has to come from AoA
<awang>
Unless that's where the majority of lift comes from anyways
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<awang>
Did I miss anything?
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<wb99999999>
no sir
<wb99999999>
no one said anything yet
<Maxsimal>
thanks schnobs, I'll check that out.
<Maxsimal>
awang: In supersonic flight, afaik, it's all AOA, slim symetrical wing shapes are typical, but I don't know of any good wings for subsonic flight. You could ask Ferram if wing profile shape matters for lift, but I kinda doubt it does.
<ferram4>
FAR abstracts away all the wing profile effects. Fundamentally they're not useful except for subsonic flight, which very few people are doing.
<ferram4>
The results that FAR uses are approximately equialvent to a NACA 6A-series airfoil with no camber.
<Maxsimal>
I shouldn't have even answered, just should have made ferram's name highlight :P
<wb99999999>
when FERRAM tells you about how FAR works
<awang>
That's quite enlightening
<awang>
Thanks!
<awang>
Didn't know profile wasn't important for supersonic flight, either
<ferram4>
Well, at least for lift.
<ferram4>
It'll affect drag, certainly.
<ferram4>
But really, the ideal wing profiles for supersonic flight are sections of 2 ciruclar arcs (top and bottom of the airfoil), a diamond, or a squashed hexagon.
<ferram4>
They all suck donkey balls for subsonic flight, which is where the engineering comes in: how to make a wing that isn't draggy as fuck for supersonic flight but actually lets the plane take off without needing F-104 amounts of speed on the runway
<awang>
So what wing profiles actually end up being used?
<ferram4>
NACA 6A-series, or similar shapes.
<ferram4>
They weren't designed for it originally, but they're a decent compromise.
<ferram4>
Not the least draggy at supersonic speeds, but to make them less draggy would make them stall at lower AoAs.
<wb99999999>
but also the design of the plane as whole helps too right?
<wb99999999>
LERX, body-lift etc.?
<ferram4>
Yes, but that gets much more complicated.
<awang>
Any advice for proper area ruling when designing a plane in KSP? Seems like it'd be pretty hard to get the kinds of subtle variation in fuselage diameter that real-life aircraft have
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<awang>
What tank utilization should be used for B9 proc wings?
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<awang>
Uh
<awang>
Apparently the B-52 wing root is 2 meters thick?
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<awang>
Seems... big
<awang>
B-9 proc wings only go up to 1 meter thick
<awang>
So much for a realistic-ish recreation
<awang>
Wait no
<awang>
I'm dumb
<awang>
Never mind
<awang>
ferram4: If FAR abstracts away wing profile effects, does that mean that the size/shape of the leading/trailing edges for wings doesn't matter much?
<ferram4>
It does not matter, but you may want to make it not look stupid for aesthetic reasons.
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<awang>
I guess a better question might be what *does* matter when messing with B9 proc wings?
<awang>
Besides the things that fall into the "base" category in the GUI
<awang>
i.e. length, width, offset, thickness?
<ferram4>
Increasing the length of the edges does affect the aero, just the same as if you increased the equivalent base parameters.
<ferram4>
Thickness tends to be more sueful in handling area ruling
<awang>
Makes sense
<awang>
Is there a way to tell how "good"/"bad" your area ruling is in the editor?
<awang>
Some kind of qualitative thing that indicates whether you should spend the time optimizing that
<awang>
Like I know about the yellow area curve thing
<awang>
But I'm not sure whether to interpret a particular curve as "eh, it's good enough" or "oh crap that's going to be causing a lot of issues later on"
<awang>
Does distance from the plane axis give a hint?
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<Probus>
I asked this before, but I was having connection problems. Does anyone know of a good mod(s) that go with ion type propulsion?