The new rocket engine

[Foxster]

The one new rocket engine announced so far for the next release is the "Vector" Space Shuttle Main Engine:

I see an issue with this though. This is called an S3 KS-25-X or one quarter of an S3 KS-25x4 Mammoth engine. It certainly weighs a quarter of it's big brother. However, it does not have a quarter of the thrust. It should be 936.5/1000 not 749.206/800.

It's not like this release is exactly over-endowed with rocket love, so I think we could at least have this one rocket engine perform a little better. No?

[passinglurker]

they said repeatedly not to trust the numbers you see in that shot the part is still in development and hasn't been balanced yet

[SpenSpaceCorp]

It was also said that "(stats are subject to balancing and may change in the release version)" in the album for this engine.

[Red Iron Crown]

I'm really curious about the specs we can't see. Does it have crazy gimbal or does it just look better when rotated as shown in the pic? Is it 295/315 Isp like the bigger version (thrust figs woudl be about right), or has that been changed too?

I don't really have a problem with it not having the same TWR as the Mammoth, it would totally dominate the other 1.25m engines if it did (and still might anyway).

[Pecan]

If it's meant to be for 'shuttle' designs the best thing about it would be a large gimbal range, for balancing thrust with and without boosters and main fuel tank.

[GoSlash27]

^ This. It's crazy- overpowered for a Kerbin- appropriate shuttle engine as it is. Mimicking a Skipper is adequate for a Kerbin shuttle analogue.

3 clipped Skippers for SSMEs.

Best,

-Slashy

Edited August 25, 2015 by GoSlash27

[Alshain]

I'm really curious about the specs we can't see. Does it have crazy gimbal or does it just look better when rotated as shown in the pic? Is it 295/315 Isp like the bigger version (thrust figs woudl be about right), or has that been changed too?

I don't really have a problem with it not having the same TWR as the Mammoth, it would totally dominate the other 1.25m engines if it did (and still might anyway).

Most likely it will not have the gimbal. It's just easier to use with the Mk3 parts. It's similar to the "Badger" engine in Vens (which does have 900 ISP) If it had the high gimbal, it would probably be harder to fly since Gimbal in KSP is entirely controlled through pitch and yaw control.

As far as TWR, it needs to be able to carry a Mk3 Shuttle with a good sized load on only 3 of them. That is the criteria they should be aiming for IMO. I think the real shuttle could carry 22 metric tonnes, or at least that was one of the heaviest payloads it did carry..

Edited August 25, 2015 by Alshain

[GoSlash27]

As far as TWR, it needs to be able to carry a Mk3 Shuttle with a good sized load on only 3 of them. That is the criteria they should be aiming for IMO. I think the real shuttle could carry 22 metric tonnes, or at least that was one of the heaviest payloads it did carry..

Ahh, but remember that was here on Earth. If you give that sort of ability to something in this game, you'll end up with something that can escape Kerbol's SoI entirely.

Gotta maintain balance with the other parts and not create something that has no relevance in the context of the game.

Best,

-Slashy

[regex]

The balance should come with a high degree of gimbal (like 8~12 degrees) and increased ISP (the range is pretty tight right now... :/ ), thrust and mass look good.

[Alshain]

Ahh, but remember that was here on Earth. If you give that sort of ability to something in this game, you'll end up with something that can escape Kerbol's SoI entirely.

Gotta maintain balance with the other parts and not create something that has no relevance in the context of the game.

Best,

-Slashy

A shuttle being able to lift 22 in-game tonnes with 3 engines (and SRB's) is not that imbalanced, that isn't even an orange tank full of fuel.

Edited August 25, 2015 by Alshain

[KerikBalm]

My only problem is that it seems a but redundant with the LVT-45 and 30... which are pretty useless once you get other engines.

The stats on the basic 1.25m engines are just.... meh... TWR is lackluster, and Isp is lackluster.

There's no good high thrust vacuum engine (aerospike is the best I guess) like a KR-2L.

There's no good booster engine - the LV-T30 doesn't even manage the same Isp as an aerospike at 1 atm, the mammoth, mainsail, twin boar, and aerospike all beat it. Its Isp is just terrible relative to other LF engines except the 48-7s.

Anyway, for this new engine, I like it because it will make SSTO 1.25 rockets easier. You'll be able to lift much more on a single node, which should lead to some very low drag designs.

If it has the same Isp curve as the mammoth, it may be a good candidate for Eve ascent vehicle engines (maybe not sea level ascents, but from elevated landing sites)

[Jouni]

Just imagine a 2.5 m stack with four of these, or a 3.75 m stack with seven of these. No more puny little Mainsails, Twin-Boars, and Mammoths for heavy rockets.

[Xyphos]

Just imagine a 2.5 m stack with four of these, or a 3.75 m stack with seven of these. No more puny little Mainsails, Twin-Boars, and Mammoths for heavy rockets.

or even 13 of them; around a 3.75 tank, one in the core, then 6 symmetrical on the top, and another 6 symmetrical on the side, slide them all into position.

also, they're small enough to fit inside cargobays for VTOL operations

Edited August 25, 2015 by Xyphos

[GoSlash27]

A shuttle being able to lift 22 in-game tonnes with 3 engines (and SRB's) is not that imbalanced, that isn't even an orange tank full of fuel.

Alshain,

A RL orbiter vehicle weighs 75 tonnes, while in KSP it's closer to 25. It'd be unreasonable to expect an orbiter to lift nearly it's entire mass as cargo.

A RL stack weighs 2000 tonnes, while a KSP stack weighs about 250.

It would be unrealistic to have a shuttle that can do in- game what the real shuttle did. If we try to include real life engines in the game, they'll break it.

Best,

-Slashy

[Mister Dilsby]

I do really like the sea level thrust numbers; right now aerospikes and mammoths seem to be the only truly viable Eve sea level motors (based on viewing the forum and not my personal experience or analysis), it would be nice to have at least one more option.

[regex]

Alshain,

A RL orbiter vehicle weighs 75 tonnes, while in KSP it's closer to 25. It'd be unreasonable to expect an orbiter to lift nearly it's entire mass as cargo.

A RL stack weighs 2000 tonnes, while a KSP stack weighs about 250.

It would be unrealistic to have a shuttle that can do in- game what the real shuttle did. If we try to include real life engines in the game, they'll break it.

That's a product of the toy solar system. RL payload fractions are around 2% or less while KSP lifters and <shudder> spaceplanes boast upwards of 25% nowadays (IIRC the current spaceplane record in KSP is @40% while the currently fictional Skylon is projected to get @4.5%). You can hardly claim "realism" as an expectation in KSP under those conditions.

Also, technically the STS Orbiter was part of the payload of its stack. Two SRBs and three RL-25s brought nearly 100 tons to orbit. If a KSP orbiter masses 25 tons, on average, and carries 22 tons it would probably need another 150 tons to get to orbit (most likely less) and wouldn't be outside the realm of KSP's payload fraction.

Lastly, I don't see anywhere in Alshain's posts where they're asking or suggesting real life engine stats, unless you're taking the "TWR" to mean the engine TWR only, which would be out of context from the rest of that post.

Edited August 25, 2015 by regex

[Windspren]

They should make it surface attachable, so we can make engine clusters without Cubic octagonal struts. LESS STRUTS!

[Red Iron Crown]

They should make it surface attachable, so we can make engine clusters without Cubic octagonal struts. LESS STRUTS!

They should do that with all engines, to be honest.

[mikegarrison]

A shuttle being able to lift 22 in-game tonnes with 3 engines (and SRB's) is not that imbalanced, that isn't even an orange tank full of fuel.

A real shuttle would not be able to lift an entire shuttle cargo bay full of kerosene. (At least, I don't think so. I didn't actually run the numbers to see.)

Right, I think I just calculated that the payload bay of a Space Shuttle, full of kerosene, would be about 1 million kg.

Edited August 25, 2015 by mikegarrison

[Jovus]

I hope if it does have a large gimbal range they put the work in to allow gimbal to actually be a range instead of a circular toggle, so the rockets using it don't just wiggle their way to space.

[Alshain]

A real shuttle would not be able to lift an entire shuttle cargo bay full of kerosene. (At least, I don't think so. I didn't actually run the numbers to see.)

It would if it massed 22 tonnes or less. (24 tonnes to LEO if Wikipedia is correct, not sure if it ever really carried 24 though, I know it did 22)

[Sharpy]

They should make it surface attachable, so we can make engine clusters without Cubic octagonal struts. LESS STRUTS!

I doubt they'd do this in stock. If you need surface-attachable engines, just install Editor Extensions, press T and surface-attach any engine you like (although fuel routing may be tricky).

Funny thing about Editor Extensions: crafts done with it are still Stock - perfectly loadable into stock VAB/SPH. Of course if you detach such an engine, you won't be able to attach it again in stock. But it's great for radially attaching jets and rapiers without need for "dummy" fuel tanks.

[regex]

A real shuttle would not be able to lift an entire shuttle cargo bay full of kerosene. (At least, I don't think so. I didn't actually run the numbers to see.)

A real shuttle almost lifted a cargo bay full of liquid hydrogen and liquid oxygen, plus payload. It was deemed too risky after the fact but, considering that other lifters do exactly the same thing day in and day out, it would not be unreasonable for a shuttle to lift a mass of fuel equal to its payload.

[Yukon0009]

The thing I really like about the engine is that there is no ugly nozzle to upper node adaptor.

[Alshain]

Lastly, I don't see anywhere in Alshain's posts where they're asking or suggesting real life engine stats, unless you're taking the "TWR" to mean the engine TWR only, which would be out of context from the rest of that post.

Yep, and really I never actually said the KSP version needed to lift 22 tonnes, I just said it needed to lift a decent payload and then mentioned what the real shuttle did. People took it out of context. But if it can't lift a good sized payload in a standard shuttle configuration, there is no point in adding the engine in the first place, because it's intended to be a shuttle engine.