Engines revamp - Thrust and performance changes discussion

[Gaarst]

So there is a file included in PorkJet's revamped parts showing the changes to engine models to be made in the future:

Besides the engines redesigns (that I personally like, but let's not discuss this here) there are some pretty heavy changes made to existing engines thrusts, especially for the "heavy" engines which were mostly nerfed.

The changes:

• LV-T30 (Reliant) boosted from 215kN to 300kN, asl Isp nerfed from 280s to 270s, vac Isp nerfed from 300s to 295s
• LV-T45 (Swivel) : asl Isp nerfed from 270s to 250s, vac Isp nerfed from 320s to 315s, gimbal boosted from 3° to 6°
• Twin Boar boosted from 2000kN to 2200kN
• Vector nerfed from 1000kN to 750kN, and extended to size 2 (2.5m)
• Mammoth nerfed to 4000kN to 3000kN (to equal 4 Vectors)
• 909 (Terrier) boosted from 60kN to 80kN 75kN, asl Isp increased to 90s (was 85s), vac Isp decreased to 340s (was 345s)
• Rhino nerfed from 2000kN to 1200kN

Also note the addition of:

• the LV-T15 Valiant, a 100kN 1.25m engine (nice numbering here: 15 = 100kN, 30 = 200kN, 45 = 300kN), dry mass 0.750t, Isps of 240s (asl) and 270s (vac), alternator and 5° gimbal
• the KR-1 Boar, a 900kN 2.5m engine (with quite a few similarities with the F-1) to fit in the gap between the Mainsail and Skipper (note how the Twin Boar is 2.4 times as powerful as a single Boar )
• the 303 Pug, a 20kN 25kN 1.25m vacuum engine (then again, 20kN is one quarter of 80kN while 303 is one third of 909) with Isps of 150s (asl) and 320s (vac), dry mass 0.175t

So discuss here. (Please don't talk about the redesigns, but focus on the thrust changes)

My opinion: at first I was against this as nerfing the most powerful engines will restrict the possibilities for very heavy rockets (also note that we are still missing 2.5m SRBs to give some kick to rockets); but on second thought, I realised that the different versions (especially the compact) will allow surface attachments, and therefore easier clustering to achieve higher thrusts. Still don't really know what to think at this point. I also don't really see what to do of all these 2.5m engines we are suddenly given since they have similar thrusts (maybe atm performance and Isp will make the difference).

 

Edit: corrected some information for 1.25m engines thanks to @Armisael's screenshots. 

Edited September 14, 2016 by Gaarst

[Sharpy]

Will there be any considerable reason to use the non-compact versions?

 

[Red Iron Crown]

27 minutes ago, Sharpy said:

Will there be any considerable reason to use the non-compact versions?

The details of the three types at the top say the boat tailed versions should be less draggy. Aside from that it seems to be mostly aesthetic to use the larger versions.

[Sharpy]

Personally, I wouldn't mind if the current versions remained as they are, while compact got the nerfed values.

Four compact rhinos on a quad-adapter, for 4800kN of thrust? Sign me in. Even if they cost the same as big.

[Frozen_Heart]

I like most of the new thrust changes.

The Reliant needed a buff to make 1.25m stacks viable, so I like that one.

Vector and Mammoth thrust nerf I agree with. They were OP as is and now act more like a sustainer engine which is what they are.

I also like the massive nerf of the Rhino. A single one could give entire capital ships a huge TWR, while it is meant to be an efficient vacuum engine and so doesn't need that thrust at all.

The Terrier however... that thing was op for a 1.25m upper stage, and they're buffing it more?! With 80kn it would work on a 1.875m upper stage though quite nicely. Add a cluster of 9 LV-T15s on the lower stage as well...

 

As for the new engines, I like all of them and they seem to fill some gaps quite well. A proper 3.75m launch engine and a greater selection of Nuke engines would be nice.

[Wjolcz]

Twin Boar got boosted? I remember making an accidental SSTO with it and 3 long 1.25m tanks on top of it. It was pretty ridiculous.

[Frozen_Heart]

49 minutes ago, Sharpy said:

Will there be any considerable reason to use the non-compact versions?

 

Maybe they will cost a bit more or something?

[Sharpy]

20 minutes ago, Frozen_Heart said:

I also like the massive nerf of the Rhino. A single one could give entire capital ships a huge TWR, while it is meant to be an efficient vacuum engine and so doesn't need that thrust at all.

I disagree. Yes, a single one could give entire capital ships decent (not huge) TWR, but did you really see the size of that thing? It's really not meant for anything smaller than capital ships.

I would be perfectly okay with nerfing its atmospheric efficiency to hell and back. It shouldn't be a viable engine for the launch stage. But there are ships that NEED that kind of thrust.
 

Spoiler

Supertanker. The vectors are an overkill, but the two rhinos are absolutely adequate for its size - it's reasonably agile, reasonably responsive, burns last reasonable time. And the engines don't burn up all the fuel it carries.

Two rhinos of current thrust are the perfect match for this craft.

Or this:

Class E Asteroid wrangler. Rhinos are exactly what it needs. It can bring a Class E into LKO depleting maybe 30% of its resources. Since asteroid hauling is a work on a schedule, the five ISRUs are fully justified; it has five longest MK3 tanks and needs to be refueled from empty to full 3-4 times per one asteroid. Still, the work takes about 3-5 hours of gameplay. I did bring a class E asteroid into LKO using nukes. 8 of them. It took me a week.

 

[Armisael]

I'm thrilled with these changes - not just because they indicate that SQUAD is willing to change well-established parts - but because they're mostly pretty good. The reliant and the twin-boar were totally overshadowed by their brethren (the reliant a little more so). The vector was definitely ridiculous. I'm also excited for the new parts; there was always a bit of a gap between the skipper and the mainsail - hopefully the boar does an adequate job of filling that.

I'm not as clear on the reasons for the terrier buff (!?) and a little concerned that the pug will squeeze the spark a little too much - it's effectively a 0.175t engine with more thrust and better Isp - since that isn't really an effective size class for lifter engines.

I may have to make an updated version of my command pod rejigger thread if they're open to doing this kind of work...

[Aegolius13]

Do we know the masses of these engines yet?  It's kind of hard to tell how each good each engine will be without that info.  (Cost is also relevant to some extent, of course).

The Pug looks pretty cool.  While the Spark is a good all-purpose small engine, I do kind of hold my nose when I put it on a vacuum lander due to its not-great vacuum ISP.  Sounds great to have a specialist engine for this role.

I am skeptical about buffing the TwinBoar unless there's some corresponding drawback.  It's already maybe a little too good compared to the Mainsail - cheaper, better thrust, ISP difference is small and not that important in a booster...

Sounds like the Boar will kind of usurp the Vector's current role as a midsize launch engine between the Skipper and Mainsail.  Since the new Vector is listed as a sustainer, maybe they'll improve its vacuum ISP a bit? (But unlikely if they want to leave the Mammoth as the big launch engine, and keep the Mammoth's stats as basically four vectors).    I already don't use the Vector much in career mode because it's cheaper to just buy a Mainsail or TwinBoar and more fuel.  

 

[Armisael]

SECOND EDIT: I made a vastly more compact form once I got home:

THIRD EDIT (because why not): it seems to me that there's a bug in the upgrade code - engines with upgrades don't display those upgrades in the right click menu. These are the un-upgraded stats. For example, the terrier doesn't cap out at 340s - it makes it to 345s at least.

Edited September 15, 2016 by Armisael

[Corona688]

They didn't nerf any engines I actually care about, nerfed several I considered OP, boosted my favorite, and boosted some which otherwise had little reason to exist, so if that's the sum total of the changes I'm happy.  I might have to redo the Dreen, since that uses a twin boar, but I can probably make do.

I still want them to un-nerf the Spark at least slightly.  We were robbed!

It's going to be nice to have a 100kN axial engine!

[edit] Argh!  They changed ISP's!  They nerfed the 909!  By a percent, but still.  They nerfed the Swivel, too, in performance and thrust.  All the starter engines are now terrible.  Unless we got a tech tree revamp too, that's really going to suck in career mode.

On first look the tiny useless fuel tanks built into all sorts of engines now are useless and tiny.  But on second thought, I use useless tiny tanks all the time and wish I'd had them earlier in career mode, so, okay, I guess.

These are some pretty big changes.  Probably save-incompatible changes, they invoke characteristics in the same parts which just didn't exist before.

Edited September 14, 2016 by Corona688

[regex]

6 hours ago, Gaarst said:

My opinion: at first I was against this as nerfing the most powerful engines will restrict the possibilities for very heavy rockets

No, not at all. Those compact designs will be incredible for clustering without ugly tankbuttes. Throw four LVT-30s and four LVT-45s under a 3.5m tank (or an adaptor with some 1.5 tanks in their own cluster) and you've got yourself a Saturn Ib. And then you can slap two Skippers under a 2.5m tank and have a Titan II. The possibilities just opened up.

 

[Frozen_Heart]

Not sure why the swivel has been nerfed. It was already underpowered. The buff to the other 1.25m engines is nice though.

[Gaarst]

3 minutes ago, regex said:

No, not at all. Those compact designs will be incredible for clustering without ugly tankbuttes. Throw four LVT-30s and four LVT-45s under a 3.5m tank (or an adaptor with some 1.5 tanks in their own cluster) and you've got yourself a Saturn Ib. And then you can slap two Skippers under a 2.5m tank and have a Titan II. The possibilities just opened up.

Yes, it's basically what I realised afterwards. On my modded save I'm already almost exclusively using surface attached engines (with the surface node thingy if necessary), and I tend to forget how much I "need" it for my designs, so yes the surface attachement is a great thing.

Still not sure if it will make up for the thrust losses of the higher power engines. I'd rather a few powerful engines than a stupidly complicated cluster using many weak ones.

[rdem]

with new "lv-t15"s i can send light boosters with tiny probes without starting to burn in atmo at about 15 km 

[lagittaja]

24 minutes ago, regex said:

No, not at all. Those compact designs will be incredible for clustering without ugly tankbuttes. Throw four LVT-30s and four LVT-45s under a 3.5m tank (or an adaptor with some 1.5 tanks in their own cluster) and you've got yourself a Saturn Ib. And then you can slap two Skippers under a 2.5m tank and have a Titan II. The possibilities just opened up.

 

Well, yeah. That's a good idea. It's just a shame that the LVT-30's and LVT-45's don't have enough oomph.

The Saturn Ib comparison is good and I just slapped one together in the VAB, two S3-14400 tanks and 4x30 + 4x45. Using the new parts of course.
TWR is under 1 and the relative dimensions of that thing is pretty much the same as the S-Ib stage except the real thing has a TWR closer to 1.6 if I calculated it correctly.
Replace one S3-14400 with a S3-7200 and you're above 1.2 TWR but now it looks too stubby.
Or you could add another LVT-30 to the center (shh, no one saw) which then gets you a little above 1.1 for launch TWR.

Yeah yeah, this isn't real life but still

[regex]

30 minutes ago, Gaarst said:

Still not sure if it will make up for the thrust losses of the higher power engines. I'd rather a few powerful engines than a stupidly complicated cluster using many weak ones.

Throw two compact Mainsails under a 2.5m tank and call me in the morning.

Edited September 14, 2016 by regex

[Temeter]

Btw, one reason the 1.25m engine ingame are so weak, are the upgrades you'll get with later tech. You can't really take their start values at face value.

 

Seems well thought out tho, even if some values are obviously still VIP. Finally early engines are weak at the beginning, but get boosted later and don't become obsolete anymore. Maybe need to be upgrade somewhat less hardcore, idk.

Vector nerf is good, making it a high ISP/medium thrust alternative to the Mainsail, more akin to a true sustainer (like the SSME), is a good choice in my book.

I also like how the classic 909 is basically split into a heavier 909 and a lighter 303.

 

Mammoth nerf is fine I guess. Means our strongest engine is weaker, but the plate-less compact engines can be much easier massed, and procedural parts can create custom fairings if needed.

Edited September 14, 2016 by Temeter

[Gaarst]

43 minutes ago, regex said:

Throw two compact Mainsails under a 2.5m tank and call me in the morning.

A stack that can be lifted by two Mainsails can be lifted by a single Mammoth. Stacks that require several Mammoth (at 4000kN) are going to need some serious redesigns.

[Waxing_Kibbous]

I'm happy the Poodle is getting a big redesign- it is currently quite ugly yet is really a meat and potatoes engine. It deserves to be a good looking unit.

[regex]

14 minutes ago, Gaarst said:

A stack that can be lifted by two Mainsails can be lifted by a single Mammoth. Stacks that require several Mammoth (at 4000kN) are going to need some serious redesigns.

So what? I don't get people so hung up on past stats, it's not like your designs are going to survive an art update anyway. Put an SRM on the side of the stack and call it good.

[Armisael]

So it turns out that there's a bug in the upgrade code, and those aren't the final upgraded stats - they are, in fact, the unupgraded stats. My apologies for the confusion.

[Jonfliesgoats]

Porkjet does amazing work!

Are we still giving ramjet engines thrust at 0m/s?  It would be nice they smoked and sputtered worthlessly until .5 Mach or so.  

 

[Aegolius13]

20 minutes ago, Jonfliesgoats said:

Are we still giving ramjet engines thrust at 0m/s?  It would be nice they smoked and sputtered worthlessly until .5 Mach or so.

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.