The Vector: Your thoughts

[godefroi]

On 12/9/2015 at 2:41 AM, LostOblivion said:

Also, remember that the rocket the Mammoth was based on, the Saturn 5 or SLS (rockets haven't changed much, have they...), had five such engines, not four, warranting at least a comparable reduction in thrust, and perhaps a model change for the Mammoth to get five engines.

The RS-25 (SSME, Space Shuttle Main Engine) is a liquid oxygen/liquid hydrogen staged-combustion cycle engine that produces ~1900 kN of sea level thrust. The F-1 (Saturn V, or more accurately, S-IC main engine) is a liquid oxygen/RP-1 (basically kerosene) gas-generator cycle engine that produces ~6800 kN of sea level thrust. While rockets might not have changed much, these two engines are very different.

[Geschosskopf]

43 minutes ago, Majorjim said:

Can we have some bigger, more useful SRBs? Thanks.

Get the Space Y mod

 

[GoSlash27]

On 12/27/2015 at 10:16 PM, LaytheDragon said:

The Vector just isn't useful for 1.25 meter things, despite it's size, so it should be compared to 2.5 meter engines instead, which are much more on par.

This about a thousand.

If we'd all just picture a 2.5m tank butt on the Vector, we wouldn't be mistaking it for some kind of wonder- engine. It's not an OP 1.25m engine, it's just a 2.5m engine minus the wide base.

Best,

-Slashy

[Temstar]

3 hours ago, NathanKell said:

Talking about size? Guess it's time for this again.

Of the following two engines, which do you think produces more thrust?

Engine 1, with a 2.14m diameter nozzle

Engine 2, with an approximately 1.3m diameter nozzle (the 4.9ft stated appears to include the pump).

 

 

RL-10 is a vacuum engine, and this example you have here is fitted with the enormous nozzle extension that is typical of vacuum engines.
H-1 is a lift off engine, and as with pretty much all lift off engines they have a much smaller nozzle. Using a big nozzle on lift off engine will cause over expansion.

If you remove the RL-10's nozzle extension then their size would be comparable, and that's because H-1 is working with RP-1 while RL-10 is working with liquid hydrogen, ie the thing with the lowest density liquid phase in the universe. To move a reasonable mass of hydrogen every second the plumbing has to be vastly bigger than plumbing for RP-1.

Vector and Mammoth only have a little bit better Isp than Reliant and Swivel so it's unlikely they use different fuel. The slightly higher Isp could easily be explain by the fact that Vector is a staged combustion cycle engine.

On that note I thought that was a really cool thing that Squad did, mentioning specifically that Vector is a staged combustion cycle engine. Now if only Squad could add a turbopump exhaust animation to the Reliant and Swivel:

[Windspren]

I think that the Mammoth should be removed entirely, leaving room to nerf the Vector. I mean, why have a separate part for a cluster of an engine? Players should be able to decide when to cluster their own engines.

[Temstar]

The clustered version has a gimbal with a much narrower range in exchange for lighter weight and cheaper cost.

Edited December 29, 2015 by Temstar

[NathanKell]

5 hours ago, Temstar said:

RL-10 is a vacuum engine, and this example you have here is fitted with the enormous nozzle extension that is typical of vacuum engines.
H-1 is a lift off engine, and as with pretty much all lift off engines they have a much smaller nozzle. Using a big nozzle on lift off engine will cause over expansion.

If you remove the RL-10's nozzle extension then their size would be comparable, and that's because H-1 is working with RP-1 while RL-10 is working with liquid hydrogen, ie the thing with the lowest density liquid phase in the universe. To move a reasonable mass of hydrogen every second the plumbing has to be vastly bigger than plumbing for RP-1.

Vector and Mammoth only have a little bit better Isp than Reliant and Swivel so it's unlikely they use different fuel. The slightly higher Isp could easily be explain by the fact that Vector is a staged combustion cycle engine.

 

That's my point, actually: nozzle exit size doesn't tell you much about thrust. And it's not that boosters have smaller nozzles per se, it's that the area ratio is usually lower (although not that much lower; a modern closed-cycle booster with, say, 70:1 or so AR has a higher AR than many early and even mid-period uppers). If you assume  that the early engines, despite their high Isp, are open cycle, pushing much lower chamber pressures, then it makes sense the Vector doesn't have a much higher form factor and instead gets its high thrust from high chamber pressure.

 

5 hours ago, Temstar said:

On that note I thought that was a really cool thing that Squad did, mentioning specifically that Vector is a staged combustion cycle engine. Now if only Squad could add a turbopump exhaust animation to the Reliant and Swivel:
 

 

You're welcome. We definitely tried to clean up the Mammoth and Rhino descriptions for 1.0x, and the Vector for 1.0.5, to that effect.

And as to turbopump exhaust, I'm sure that Porkjet is at least considering it, though of course all plans are subject to change.

[tg626]

My only gripe with the vector as a shuttle engine is that I wish I could lockout roll and only have it gimble for pitch and yaw.  Those nozzles look silly swinging all around as I roll my shuttle "upright".

It would also be nice if all engines stopped gimbaling when the engine was shut off.

[RocketBlam]

I don't get what people mean by engine butts... What are they?

[Red Iron Crown]

1 hour ago, RocketBlam said:

I don't get what people mean by engine butts... What are they?

The wide base at the top of the engine model, usually sized to match one of the tank sizes. They look fine when used on the "right" size tank but bad when used on any other size tank (particularly smaller tanks).

[NecroBones]

 

When it comes to game balance with the engines, I think what matters most is the ISP and the "thrust to mass" ratio, since those two things factor into your overall Delta-V (understanding that thrust isn't part of that equation, but matters relative to the mass for purposes of liftoff capability and how much "bang for the buck" you get with your on-bard mass).

 

With that in mind, the Vector is 25% of the thrust of the Mammoth, but 26.67% of the mass. Four Vectors would weigh one ton more than a single Mammoth. The thrust and ISP would be the same, but the mass is higher to split it up into individual engines. So in my mind they're not cheaty at all, unless you think of the Mammoth as cheating first. I think a "mass tax" is fair for splitting out individual engines. But also am glad that it's late in the tech tree, because of their effectiveness in that form factor. For sandbox games, this is always an issue in any game that allows for sandbox alongside a progression system, that some items will be obsolete right out of the gate. But even so, the smaller 1.25m engines aren't completely obsolete, just mostly so in that case.

 

[Red Iron Crown]

I dunno, @NecroBones, a large engine sets a minimum size where it's useful. Having a fraction of that big engine makes it more useful in a lot more situations. I.e. there are many rockets that could use the Isp/TWR of the Mammoth but aren't big enough to need 15t of engine or the 3.75m form factor. For those rockets the Vector is competing with Mainsails and Skippers while the Mammoth does not.

[NecroBones]

Yeah, that is a good point, and to be fair, that's also why I didn't make anything stronger than the "Kiwi" in that form factor in SpaceY.

[MaxL_1023]

The Vector is hilarious when using tweakscale - the 1.25m base size makes a 3.75m vector several times more powerful than a Mammoth. Besides that, nothing is really wrong with it performance wise besides the weirdness resulting from sticking one on a 1.25m stack and getting insane TWR.

I think it should be a 2.5m part with the same model (add a plate attachment or something) but that is not a major issue.

[GoSlash27]

10 minutes ago, MaxL_1023 said:

I think it should be a 2.5m part with the same model (add a plate attachment or something) but that is not a major issue.

 That is actually precisely the reason the Vector was made; a proper shuttle replica needs 3 Skippers for SSMEs, but the tank butts tend to stick out. The Vector was built with the intention of clustering for shuttles.

It's a 2.5m engine with the (2.5m) tank butt removed. It's guts are supposed to be hidden inside the parent part.

1.0 shuttle. Note the protruding tank butts.

1.05 shuttle. Vector FTW.

Best,

-Slashy

 

Edited December 29, 2015 by GoSlash27

[Tweeker]

     To me this engine is super broken. Not only does it dwarf the existing 1.25m engines, it also breaks the Mammoth, you can cluster multiple vectors to make a 3.75m engine that outshines the Mammoth.

 .    So what to do about it? If you tweak the stats it step on the idea of the Vector being 1/4 of a Mammoth. I really think the engine need to be upsized to 2.5 meters, that would take care of the problems vis-à-vis  1.25m engines. You can still build a 4 engine cluster that is similar to the Mammoth but does not outshine it.

      But changing the engine size is something that squad will never do. I think we are stuck with this monstrosity. I just wish they had thought a little before crapping this thing out.

[Red Iron Crown]

@Tweeker Four Vectors are heavier than a Mammoth and much more expensive, if you need that much thrust the Mammoth is a better choice.

[r_rolo1]

2 hours ago, Red Iron Crown said:

@Tweeker Four Vectors are heavier than a Mammoth and much more expensive, if you need that much thrust the Mammoth is a better choice.

Yeah ... if you could hack the Mammoths to take the Vectors out of it, you would make a tidy profit

Edited January 13, 2016 by r_rolo1
two outs makes a bad sentence ...

[Dr.K Kerbal]

Did you know there are four vectors on the one mammoth?

[I_Killed_Jeb]

2 hours ago, Tweeker said:

     To me this engine is super broken. Not only does it dwarf the existing 1.25m engines, it also breaks the Mammoth, you can cluster multiple vectors to make a 3.75m engine that outshines the Mammoth.

 .    So what to do about it? If you tweak the stats it step on the idea of the Vector being 1/4 of a Mammoth. I really think the engine need to be upsized to 2.5 meters, that would take care of the problems vis-à-vis  1.25m engines. You can still build a 4 engine cluster that is similar to the Mammoth but does not outshine it.

      But changing the engine size is something that squad will never do. I think we are stuck with this monstrosity. I just wish they had thought a little before crapping this thing out.

As has been stated multiple times over and over again, the Vector is a 2.5m engine in 1.25m form factor. Its usefulness is very narrow and scales extremely logically with the other engines in the 2.5m class.

[Tweeker]

Quote

Yeah ... if you could hack the Mammoths to take the Vectors out of it, you would make a tidy profit

  Or you could just charge 50% more for a quarter of a mammoth.

Quote

As has been stated multiple times over and over again, the Vector is a 2.5m engine in 1.25m form factor. Its usefulness is very narrow and scales extremely logically with the other engines in the 2.5m class.

 

      If it "really" is a 2.5m engine then make it a 2.5m engine.

Otherwise this argument just opens the door to all kinds of other problems, like a 1.25m poodle or a .625 meter swivel.

Edited January 13, 2016 by Tweeker

[GoSlash27]

7 minutes ago, Tweeker said:

If it "really" is a 2.5m engine then make it a 2.5m engine.

As I said earlier, that would defeat the entire point of the Vector. It's *supposed* to be a 2.5m engine in a 1.25m form factor so we can make nicer shuttle replicas.

9 minutes ago, Tweeker said:

Or you could just charge 50% more for a quarter of a mammoth.

People who actually care about the price don't use the Vector. People who use the Vector don't care about the price. There's no balancing it by adjusting the price.

Best,

-Slashy

 

[I_Killed_Jeb]

13 minutes ago, Tweeker said:

 

     If it "really" is a 2.5m engine then make it a 2.5m engine.

Otherwise this argument just opens the door to all kinds of other problems, like a 1.25m poodle or a .625 meter swivel.

This is a problem... why? Again, you have yet to provide any compelling evidence of its OPness and haven't even addressed my statement that its use range is narrow.

[Tweeker]

7 hours ago, I_Killed_Jeb said:

This is a problem... why? Again, you have yet to provide any compelling evidence of its OPness and haven't even addressed my statement that its use range is narrow.

      I pretty sure I'm not the 1st person to bring this up, but if you insist,

   The Vector is 5x more powerful than the Reliant/Swivel, an equivalent would be a 100 KN .625 engine. Tell me that doesn't sound OP.

 It is better than the Reliant/Swivel in ISP.and TWR, but it costs only 3x more than a cluster of Reliants with the same thrust. But you would need 7 or 8 Reliants to do the same job, so the cost is really closer to only 2x  This cost doesn't really serve to balance it's high stats, because you need more fuel for the Reliant cluster, about 180% of the fuel you would use with a single Vector.  So with the Reliant cluster you end up burning all your cost savings in extra fuel. In fact you can recover a much greater percentage of the rocket's cost with the Vector.  

Make it a 2.5M engine and you avoid all of this. It slots into the 2.5M range OK, not great, but OK. you can redesign the mammoth to reflect this:

Edited January 14, 2016 by Tweeker

[GoSlash27]

3 hours ago, Tweeker said:

      I pretty sure I'm not the 1st person to bring this up, but if you insist,

   The Vector is 5x more powerful than the Reliant/Swivel, an equivalent would be a 100 KN .625 engine. Tell me that doesn't sound OP.

 It is better than the Reliant/Swivel in ISP.and TWR, but it costs only 3x more than a cluster of Reliants with the same thrust. But you would need 7 or 8 Reliants to do the same job, so the cost is really closer to only 2x  This cost doesn't really serve to balance it's high stats, because you need more fuel for the Reliant cluster, about 180% of the fuel you would use with a single Vector.  So with the Reliant cluster you end up burning all your cost savings in extra fuel. In fact you can recover a much greater percentage of the rocket's cost with the Vector. 

Why would anyone want to cluster Reliants? Any larger form factor engine would outperform them in the same real estate.

I think the flaw in your comparison comes from your overestimation of the value of thrust. Thrust isn't like Isp where "more is better". Any thrust beyond "enough" is simply wasted mass and cost.
A more valid comparison between engines is which one can do the job with a lighter stage and lower cost.

 The only reason you're comparing the two engines is the shape. Yeah, a Swivel clicks on to a 1.25m node, but that's all it has in common with 1.25m engines. It has the weight, cost, and thrust of a 2.5m engine and that's what's really important.

Best,
-Slashy