Kerbomax Mainsail

[trekkie_]

I think she's almost ready for the party...

now I just gotta work out the config fx definitions (not sure what will look best, suggestions?), the thrust/isp, and the heat animation.

-

Edited October 11, 2013 by trekkie_

[rasheed]

dat engine!

Im making a 1.25m 3 engine block to bridge the gap between 909 and 45.

Pics coming soon

[trekkie_]

hmmm I wonder...are emissives different in the newer unity/ksp? can't seem to get the animation going properly.

[astropapi1]

Do want.

Extra space-filling text to reach the 10 character minimum.

[hoojiwana]

hmmm I wonder...are emissives different in the newer unity/ksp? can't seem to get the animation going properly.

Nope, same way of making them. Are you calling the right animation name in the config?

[trekkie_]

Nope, same way of making them. Are you calling the right animation name in the config?

well I'm just not seeing the emissive option in the animation window. I tried adding it with changing just the main color rgb, but no dice. animation name is just fine.

Edited October 11, 2013 by trekkie_

[trekkie_]

ok anyone have any suggestions for thrust/isp at 1.25 or 2.5m sizing? I also have a 1.25m or 0.6m high vacuum isp variant, and suggestions on that would be welcome as well. basically, something in line with what's out there without being cheaty. I don't play the game much anymore, which makes it difficult to figure out fair configs. I always like for people to be able to have a bit more efficiency than regular stock parts.

I have been pondering high-ish atmo isp, and really low vac isp.....but this causes a problem because the last leg of getting to orbit out of the atmosphere can really eat into fuel. but that might be an interesting mechanic to have to work around, possibly having to jettison the first stage before you've even reached orbit or risk excessive fuel usage, then using service engines to get you the rest of the way there. that's if it was a 2.5m part though.

Edited October 15, 2013 by trekkie_

[Reddragon]

Well for the 'Mainsail' the ISP parameters is 330 in vac. and 280 in atmo. I think the best of thrust would be around 1000-1100 with ISP of 345 vac. and 295 in atmo (if you want higher ISP). For the 1.25m one a 140-150kn would be good with an ISP of 370 in vac.

Edited October 15, 2013 by Reddragon
Corrected vacuum vs.athmospheric values of ISP

[NathanKell]

If you're going for a vacuum optimized engine, can we pretty-please have one with a vacuum-optimized nozzle? Tiny throat, in particular.* Almost all the engines (stock and mod) look optimized for sea level.

*if you make the throat tiny, you won't even have to lengthen the nozzle much.

Sea level nozzle: low area ratio (exit:throat), shorter nozzle, lots of curve, but relatively straight at nozzle end

....==

.../....\

../......\

.|........|

Vac Nozzle: high area ratio (exit:throat), only very slight curve--"stretched bell" rather than "full, wide bell"--but still angled out at end of nozzle

....=

...|.|

..|...|

..|...|

.|.....|

Some vac nozzle examples: http://www.flightglobal.com/blogs/wp-content/uploads/mt/flightglobalweb/blogs//hyperbola/rl10bcompare.JPG

(an RL-10 and some nuclear thermals)

As for thrust and Isp...we could definitely use a 1.25 of around 120-150 thrust. Isp in 909 range but worse at SL, like 180/390. Mass 0.8-1.0t?

For .625, something of thrust 40 and same stats would be nice. Say a mass of .3 tons to stay balanced.

Lastly, as a general rule, you will _never_ get as high Isp in atmo as you do in vacuum, even for a sea-level-optimized nozzle. Air interferes too much, period. Heck, the stock engines get nearly aerospike-level performance as it is (and Squad's Aerospike is just crazy...not even hydrolox engines with vacuum Isps in the 450 range get more than 360-370s at sea level!)

Edited October 15, 2013 by NathanKell

[trekkie_]

Well for the 'Mainsail' the ISP parameters is 330 in vac. and 280 in atmo. I think the best of thrust would be around 1000-1100 with ISP of 345 vac. and 295 in atmo (if you want higher ISP). For the 1.25m one a 140-150kn would be good with an ISP of 370 in vac.

see, that sounds good....but it's soo much larger than the mainsail at the 2.5m sizing, it just doesn't seem realistic for it to put out less thrust unless it had an ISP to make up for it. then you've got to consider weight of the engine itself into thrust/isp, otherwise you could end up with something that either guzzles fuel to the point of no incentive to use it, or makes it too cheaty.

the only reason why I'm shying away from the 1.25m sizing is because there's soo much detail, it gets a bit of shimmer from all the small geometry when viewed at a distance. but 1.25m probably will be the final sizing. that way people can use it for landers

the thing about thrust, is I can always increase the weight with thrust so it's a bit more realistic. for example, say I make it 300 thrust...but with a relative weight to match compared to the 200 thrust engines, but with some efficiency that allows you some extra fuel to play around with.

as for the high isp version....perhaps 100 thrust at a 1.25m level or 50 thrust at a 0.6m level (clustered for greater effect)

Edited October 15, 2013 by trekkie_

[Reddragon]

see, that sounds good....but it's soo much larger than the mainsail at the 2.5m sizing, it just doesn't seem realistic for it to put out less thrust unless it had an ISP to make up for it. then you've got to consider weight of the engine itself into thrust/isp, otherwise you could end up with something that either guzzles fuel to the point of no incentive to use it, or makes it too cheaty.

You're right about that. Sorry, I made a mistake by not paying attention to the size of the engine. The only reason I thought about a bit less thrust is that way we had an engine somewhere halfway between 'Mainsail' and the 'Skipper' 2.5m engines. In my opinion it shouldn't really have to go higher than 2300-2500. ~2100 sounds be the best for the stock parts I guess keeping in mind the constant unsability of the rockets at high thrust/normal gimbal range. Bobcat's Ares 1, Ares V and N1 are the best examle of unstability this way scince if the heavy payload starts to wobble even the new ASAS is struggling to keep it on track and as that it's going to be a heavy lifter engine it's recommended to keep an eye of the large payloads.

Edited October 15, 2013 by Reddragon

[BahamutoD]

I can't tell if you're already doing this but the ridges on the nozzle are perfect for using Normal mapping. Looks like it will save you alot of tri's.

[trekkie_]

here is what the vacuum variant currently looks like.

[trekkie_]

I can't tell if you're already doing this but the ridges on the nozzle are perfect for using Normal mapping. Looks like it will save you alot of tri's.

they are aren't they? I mean, I could probably just bump map them lol. I could play with the idea, but the triangles really aren't a problem unless you're putting tons of these on a single ship. I'm not sure if it would look as detailed being bump mapped, especially on the lighting side. there's a lot of good angles where the specular catches it just right and gives it depth.

Edited October 15, 2013 by trekkie_

[NathanKell]

As long as you lower the gimbal, you should get pretty good stability at 2500 thrust, I'd think?

Regarding vac version--sorry, I'd forgotten you'd already created a vac version; the curvature looks right at the exit, the only thing I'd suggest would be the throat shrinkage. By a _lot_.

For the "regular" 1.25m version--I'd love one in the 300-350 range! The T45 just isn't strong enough for tall 1.25m stacks. _Especially_ if you play with lowered Isp, as I do!

EDIT: Ninja'd by repost of vac version. But I stand by my area ratio comment: that's still got the area ratio of a sea level-optimized rocket. Just a somewhat more efficient one, because of the longer nozzle. Does have the right curvature though. Try a throat of 1/2 to 1/4 the diameter.

[trekkie_]

the issue is that it's hard to make look right, especially since the base is more wide than long. shrinking the neck doesn't look right, but neither does enlarging the base (because then it just looks like a high thrust payload to orbit deliverer)

you could always imagine that maybe there's some cone on the inside that attached to the neck, so that the neck doesn't have to be that small visually. or I'm sure it'd be useful as a sea level optimized rocket with the correct settings, perhaps for medium thrust landings or winged flight, especially if it was 0.6m

here's an example of what I mean. it kind of look like the base is just teetering on the skirt.

Edited October 15, 2013 by trekkie_

[trekkie_]

ok, I think I came up with a compromise...

[NathanKell]

Um, sorry to further trouble you, but I meant to keep the curvature as it was, i.e. smooth, continuous bell. If you also scale inward the next edge loop by almost as much, and the next by some less...

And yeah, vacuum rocket engines do look like that, teetering on a tiny throat. The RL-10 isn't as bad as some Russian ones, but:

But I take your point on not making it too skinny--I think the throat width on your last pic is fine. I'd just make the curve of the nozzle much more continuous to match. Other than that, looks super!

[trekkie_]

what I'm saying is, that the nozzle you see externally, may look like it would have a wider neck than what it actually could be. the nozzle itself doesn't necessarily have to start from where it begins to protrude externally. also while the neck may look wide in relation to the base, that doesn't necessarily mean that the neck itself is large in relation to other things. for example, if I shrunk down everything above the nozzle on the stock atomic engine, the nozzle would look a lot wider at the neck. also you've gotta leave some room for creativity for a unique look if you think about it, the internal shape could easily be different from the external shape.

Edited October 15, 2013 by trekkie_

[Kommitz]

they are aren't they? I mean, I could probably just bump map them lol. I could play with the idea, but the triangles really aren't a problem unless you're putting tons of these on a single ship. I'm not sure if it would look as detailed being bump mapped, especially on the lighting side. there's a lot of good angles where the specular catches it just right and gives it depth.

Good texture work can do loads to add the illusion of depth to something, and often the illusion is enough to fool you. Bac9 is brilliant at this with most of his textures (and KOSMOS is good too and personally I like some of my work tbh ). You don't necessarily even need to use a normal map.

As it is I think people might be glad that detail is done in geometry rather than textures for KSP though, due to the damn memory limitations. And really there's hardly ever that much on screen that would worry anyone about polycounts.

[NathanKell]

Oh I take your point about the throat being hidden, that's why I said the last pic you posted had a fine throat width. I was just talking about the very discontinuous outer curve that makes it look both wrong for a nozzle, and low-poly--quite unworthy of the very pretty engine you have there!

[trekkie_]

is it that far fetched that it could be a nozzle though? I could see it as possibly something like a feasible load bearing design measure. or if you look closely at the angles, it could even be something like a shock absorber where it retracts into the base, either from landings or sudden max thrust. not functionally in-game though of course lol.

also I think with this minor change, they could be a color coded set..

and I still have no clue what to name them either heh.

Edited October 15, 2013 by trekkie_

[NathanKell]

I'm not saying it can't be a nozzle, just that it looks really weird and low-poly with that sharp edge there. If you really want that kind of drastic curvature on the outside (and a smoother one on the inside), at least chamfer the edge loop.

IMO if you followed the curvature of the inner side of the nozzle on the outer side, it'd be perfect.

And as to the inside not tracking the outside--why do that? It just adds unnecessary mass and uneven heating to the nozzle. (And higher drag, but this is a vacuum engine that will presumably be hidden inside a fairing in atmo).

All that said, it is your model of course. I'm just offering opinion and suggestions.

[trekkie_]

I always welcome suggestions.....It's just with the base itself, it doesn't look right and I;m not sure what to do to make it look right yet...

basically, it's a struggle between the size/shape of the base, vs the skirt. you balance out one, and it throws off the balance of the other. after all, this model is sleek, but simplistic. there's not a bunch of little equipment and tubes protruding from the body to help balance things out or shift focus.

this shaping balance kind of feels better though, but still not sure.

maybe even better...

but remember, you've gotta consider the angles people will be viewing them from.

Edited October 15, 2013 by trekkie_

[MinerEdgar]

I like the last one.