Engines revamp - Thrust and performance changes discussion

[NoMrBond]

I hope the final revision of the upgrades system allows you to toggle/cycle between the various (clean / boat-tail aero cover / compact base) setups rather than having each one as a separate 'pick' in the SPH/VAB parts lists, that feels like it would get super cluttered super fast.

[regex]

"This design sheet assumes a mesh switching PartModule that allows for multiple sub versions of a part."

So, probably?

[Francois424]

Not keen at first to see every engine rebalanced... mostly because I'm lazy and have long learned what works, with what tanks, and what I need to get wherever I want (well except to Moho apparently).

But the bottom line is that I don't really care.  As long as the options are there to keep my landers efficient, do-able and keep their good looks, I'll be happy.

At the very least, it's going to remake launching rockets exiting for a while, until I figure out what I like and what I don't like anymore... I used to like Mainsails, then switched to Vectors, we'll see what my launchers end-up with next.
(PS: I hope we get a chemical 500 ISP engine to competition the Nerva is time around...  Something that would make sense to use in other situation.  Poodle was good, but ultimately it lacked the LV-N awesome efficiency too quickly.
 

[passinglurker]

Kerbal has never had a total balance overhaul not even in early access (and no the new aero rebalance doesn't count that was just the engines and just a bandaid job to compensate for it taking less dv to reach orbit) that being said I don't expect the asset dump teasers stats to hold up in the face of everything being changed at the same time and personally thats the way things should be one last big shake up to end all shake ups... until they start adding and improving planets but that's a can of worms for another day...

50 minutes ago, Francois424 said:

PS: I hope we get a chemical 500 ISP engine to competition the Nerva is time around...

that is easier said than done. you see max isp even if assuming hydrolox propellants is only roughly mid-400's. Technically lithium-fluorine can break 500 but its extremely toxic and dangerous why it makes hydrazine look like water by comparison. Best you can hope for is a nuclear engine that trades efficiency for thrust like porkjet's atomic-age lantrn engine in which case why wait? you can just mod it now

[Francois424]

Just now, passinglurker said:

Kerbal has never had a total balance overhaul not even in early access (and no the new aero rebalance doesn't count that was just the engines and just a bandaid job to compensate for it taking less dv to reach orbit) that being said I don't expect the asset dump teasers stats to hold up in the face of everything being changed at the same time and personally thats the way things should be one last big shake up to end all shake ups... until they start adding and improving planets but that's a can of worms for another day...

that is easier said than done. you see max isp even if assuming hydrolox propellants is only roughly mid-400's. Technically lithium-fluorine can break 500 but its extremely toxic and dangerous why it makes hydrazine look like water by comparison. Best you can hope for is a nuclear engine that trades efficiency for thrust like porkjet's atomic-age lantrn engine in which case why wait? you can just mod it now

Yeah I know about modding, I've had my own engine parts since 0.23.  But having stock part means auto-updated and correctly balanced for what the devs what them to be.

Given the choice, I like my eggs stock !

[Jonfliesgoats]

10 hours ago, Tweeker said:

I looked at it before I posted my statement, and again after.

The vector is a SSME analogue, hard to argue agaist that,

But the compact version omit much of the machinery

 

The compact version has only about 1/2 of the pumps ect, and none of the mounting strurcture

i was looking at a post regarding upcoming jet parts and they have to be able to fit inside appropriately sized parts, like real engines inside cowlings.  Perhaps something similar would work for these motors?  I imagine that would be a pretty big task, though.

[cfds]

The main problem is that the 909 in this draft has a way to small nozzle for a 80kN vacuum engine.

[Sharpy]

On 15.09.2016 at 4:08 AM, Aegolius13 said:

Like the Whiplash?  I know very little about real life engines, but aren't the SR-71 engines ramjet-ish, and still capable of flying from standstill (albeit not at great performance)?  Ditto for the SABRE, at least as designed.  

I believe Whiplash is a kind of hybrid. J58 is a turboramjet, "bleeding air from the compressor to the afterburner".

Pure ramjet has no moving parts whatsoever, just a cleverly shaped combustion chamber.

[Sharpy]

15 hours ago, Tweeker said:

The problem with the compact design is it turns rockets into "magic nozzels" by omitting the turbo machinery and the support structure that hides under the boat-tail. The vector is a prime example of this.  

Let me remind you:

 

[Temeter]

Btw, in case someone is still confused about how what's engines and what's the tankbutt, this pictures shows it quite nicely:

[Tweeker]

4 hours ago, Sharpy said:

Let me remind you:

 

I am well aware of the problem with jets, And they need to be fixed too,

However  I rarely build planes, so it concerns me less .

But using one wrong to justify another is,... wrong

   

 

[Sharpy]

13 minutes ago, Tweeker said:

I am well aware of the problem with jets, And they need to be fixed too,

However  I rarely build planes, so it concerns me less .

But using one wrong to justify another is,... wrong 

At least it's consistently wrong!

[passinglurker]

1 hour ago, Sharpy said:

At least it's consistently wrong!

I'd take mild consistency over hyper realism any day! 

[Tweeker]

2 hours ago, Sharpy said:

At least it's consistently wrong!

No, it is inconsistent

Rockets are 1 way, and jets another. Because I don't fly aircraft I can ignore the way the jet engine are.

Most of the rocket engine where fine as they were, and they were consistent, But now the vector, and now some of the new "compact" engines are changing this, for the worse.   You are getting some rockets that have the thrust structure on them ,and some that don't..

Quote

1 hour ago, passinglurker said:

I'd take mild consistency over hyper realism any day! 

 

The thing is the engines where consistent before the vector came along; they all had a thrust structure at the top Then because the space plane people wanted a real looking space shuttle we got the vector. So instead of consistency we get something that looks real, in one instance, (on the shuttle) and wrong in others, (when put on a rocket)

[Ultimate Steve]

I'm okay* with most of this. Just, PLEASE don't make the Vector 2.5m.

EDIT: Oh, hey. The compact version is 1.25m.

Edited September 16, 2016 by Ultimate Steve

[passinglurker]

56 minutes ago, Tweeker said:

No, it is inconsistent

Rockets are 1 way, and jets another. Because I don't fly aircraft I can ignore the way the jet engine are.

Most of the rocket engine where fine as they were, and they were consistent, But now the vector, and now some of the new "compact" engines are changing this, for the worse.   You are getting some rockets that have the thrust structure on them ,and some that don't..

The thing is the engines where consistent before the vector came along; they all had a thrust structure at the top Then because the space plane people wanted a real looking space shuttle we got the vector. So instead of consistency we get something that looks real, in one instance, (on the shuttle) and wrong in others, (when put on a rocket)

First you are wrong the power train will still be modeled and visually represented after the revamp it's been proven to you over and over and you are way out of line to keep bringing this up.

Second unless you are a legitimate aerospace engineer I don't think you are qualified to judge these parts for how their mechanical complements are represented,

and Third (and I can't emphasize this enough.) If you don't like the compact engines then don't use them!

[IronCretin]

3 hours ago, Temeter said:

Btw, in case someone is still confused about how what's engines and what's the tankbutt, this pictures shows it quite nicely:

I loved those books when I was a kid!

[septemberWaves]

I love the new changes to the engines, partly because of the appearances, partly because of the upgrade system that compensates for what initially appears to be a huge all-round nerf, and partly because of the new engines. The Boar in particular I think will be incredibly useful to me, since I have several vehicles that require a mid-range thruster between the Skipper and Mainsail, and now that's doable in stock.

[NathanKell]

20 hours ago, Tweeker said:

Just because it is simplified, doesn't mean it is inaccurate. There is enough space under the tankbutt for the powerhead to exist, that is enough, just the suggestion that it is there. The compact version doesn't give that impression, and that is what makes it inaccurate.

You're aware the turquoise bit is the throat, right? Not the purple bit?

 

Also, regarding Isps. I goofed badly with the T30's Isp and have been rueing it ever since. I cannot imagine how tiny a nozzle a 280-300s Isp spread would imply. And on that note generally, it's worth pointing out that the current hallowed, storied engines stats are...some interim values I proposed during 1.0 QA that never got refined further. So don't put too much stock in them.

[Temeter]

1 hour ago, IronCretin said:

I loved those books when I was a kid!

Me too, it's crazy how much detail you get just by drawings, isn't it?

Edited September 16, 2016 by Temeter

[NoMrBond]

3 hours ago, NathanKell said:

Also, regarding Isps. I goofed badly with the T30's Isp and have been rueing it ever since. I cannot imagine how tiny a nozzle a 280-300s Isp spread would imply. And on that note generally, it's worth pointing out that the current hallowed, storied engines stats are...some interim values I proposed during 1.0 QA that never got refined further. So don't put too much stock in them.

Ungoof it, carpe jugulum!

I suggest 256-290, for... uhh, no reason in particular. /cough

[Tweeker]

5 hours ago, NathanKell said:

You're aware the turquoise bit is the throat, right? Not the purple bit?

 

Also, regarding Isps. I goofed badly with the T30's Isp and have been rueing it ever since. I cannot imagine how tiny a nozzle a 280-300s Isp spread would imply. And on that note generally, it's worth pointing out that the current hallowed, storied engines stats are...some interim values I proposed during 1.0 QA that never got refined further. So don't put too much stock in them.

I understand where the throat is, thank you.

The problem is in the term "tankbutt" I haven't ever seen that  outside of KSP. I think it is more accurate to call the area above the powerhead, and the thrust structure. By call it "tankbutt" instead many people try to make the case that it is part of the tank, and therefore ok to remove.

Quote

There's no larger machinery under that cone, it's tankage. The compact and full-size Rhino are exactly the same engine, it's just that one has the bottom of a tank on it.

  That is, however not the case, for a couple of reasons,  First, In KSP the tanks do not protrude  out of the ends of the second even on the Saturn's upper stage this isn't the case

,

The fuel tank ends about where the helium tanks are, Between the  top of the engine and the bottom of the tank is the thrust structure (I apologize if I am being patronizing here , but people repeatedly insist that this are is fuel tank butt of the fuel tank.)  If the skirt of the tank above extended to cover the end of the tank and the current  Rhino,  where a 2.5m engine it would approximate this stage very well.

  

The  new Rhino  is taller, and might be even better, but the compact version is the cutoff at the powerhead, and does not include any provision for the thrust structure. or interconnects which would take up space above the engine. such as in the 2nd stage of the Saturn, The power head does not mount directly to the bottom of the tank.

 

The vector, even the new one is even worse, the powerhead in the compact model is too short;

The power head needs to be at least 33% taller, or It needs to be wider, or the power head needs to be offset to one side.  

 

As far as the rest of the engines rest of the engines go,  I don't think a new art pass is needed, and I don't like the art I have seen. Some of the new engines seem a bit redundant, the 303 for example is almost exactly on top of the spark, thrust wise, It seems like the Isp will make it more space tuned, But still it is too close to the spark's niche.

For a longtime this was my main complaint about the LV-T 30 & T 45. They where essentially snow clones of each other I am glad you are pushing the farther apart, and very glad that one of them is is being pushed up to the 300 kN range. I am not entirely sold on the LV-T 15, It makes sense that it is  a fractional size of the other 2 engines, but the ISP wise the quoted stats are extremely bad.     

I am glad you are nerfing the Vector, it still needs to be nerfed more more, but it's getting closer to where it needs to be. 

I wish you would ditch the  Twin Boar and Mammoth entirely, and replace them with a bi- and quad- adapter, and add more adapters as well, maybe a 5 way for Apollo type applications, I think having adapters that you could mount whichever engine you choose, would be much more versatile than having dedicated dual and quad engines.

The poodle really needs a buff, it's main problem is the way it relates to the 2.5m parts,  While the poodle can be viewed as basically a 4X version of the LV-909, the other the equivilant parts don't follow this trend,. The small fuel tank in the 2.5m range is 9X heavier,  The capsule is  5X heavier, The lander can is  the best of the bunch at being just over 4X heavier than the 1.25m version. The result of this is that it's TWR in a stack moves in a very granular way. If it was 50% -60% larger it would give you a lot finer adjustment.  Buffing the LV-909s thrust will make the poodle shortcomings that much more obvious. Consider tweaking the poodle instead.  

One last thought I had while writing this, It would be fantastic if the engines could serve as size adapters like the J-2 in between  the Saturn II and the Saturn IV-B stages. I would like that WAY more than having boattail/bare vesions of engines.

And finally sorry for going on so much.

 

 

 

[Temeter]

1 hour ago, Tweeker said:

The vector, even the new one is even worse, the powerhead in the compact model is too short;

The power head needs to be at least 33% taller, or It needs to be wider, or the power head needs to be offset to one side. 

How often do we need to tell you that the engines aren't supposed to be accurate representations of the real engines? It's the same with the Rhino, which is also about 66% size for evertything above the throat.

Edited September 17, 2016 by Temeter

[Red Iron Crown]

12 hours ago, NathanKell said:

...So don't put too much stock in them.

You put the stock in them, they're stock.  

[Araym]

I like the change on the Vector: 1.1.3 one is pretty heavy (considering Squad balance the thrust directly making the engine heavier).

For Shuttle replicas (a single, long, Mk3 cargo, as Inigma's one), I always found them making the back too heavy at 4 tons (x3= 12 tons), ending my shuttle always dragged "tail first" by the sheer weight of them. Casually, I always "edited" an engine (duplicating the part as new one) as "Light Vector" at 3/4 of its stats, casually at 750kn of thrust (like the above), 3 tons engine, as it was pretty good as "shuttle engine" with the appropriate stack of SRBs to cope with the diminished thrust at launch.
I'm not worried by making it (in the "standard" and "boattail" version) a 2.5m engine, as there will be always the "surface mounted" one like now (and, differently like now, it is no more considered a 1.25m engine, as weight and performance are NOT of that class)

For the TwinBoar, up to now (aside from aestetic point of view) I always found him pretty overshadowed by other engines, counting it has a tank already joined toit, diminishing the use as a "pure engine": a "buff" of its characteristics stay well with this downside (used as a booster or in very specific designs, when any other engine could used in many different combinations).

I like the Mammoth to be more like a 4xVector (more or less) engine block, making it a good comparison with the future STS rocket that will use Shuttle engines in real life

Overall, even if some engine will loose some of their actual performances, if the plans are to give us  for all of them a "surface mounted" version, I think we could gain a lot more of engineering possibilities: like said, it will be possible to stack in "smaller places" more engine than now (just considering how difficoult was, for example, to stack side by side actual Mainsail eben in a 3.75m stack, having that big base as mounting point).

Obviously, we need more infos about their weights: will a "boat-tail" version (less draggy) weight as a "standard" one, or it will weight slightly more (as it has more structural part to shield it)? Will a "surface attaccable" one weight less compared to the other two version, even if probably more draggy to compensate? Will have weight based on "structural construction of an engine", rather (like now) simply tonnage numbers based on the pure thrust value of them? As pointed above, I "edited" a copy of the Vector just to have a visual shuttle-alike engine, rather, as like the Inigma's Shuttle that teached me how to balance it, a 3x Skipper, visually "bigger" and "bulkier", but way less heavy and powerfull enough to do a "shuttle engine job", as Thrust/mass proportion were more convenient and gives better balance (during gliding reentry) on any "standard" shuttle I build.