What engine do you guys consider to be over powered and game breaking?

[UnusualAttitude]

I keep wondering why people think the airbreathing engines are OP then I remember FAR halves the thrust on them.. and they're still pretty OP after that. Though, that's mainly for gameplay reasons, I reckon - 1 engine to get plane up to high speed, another to be a sc/ramjet or similar to really push the edges of atmospheric ability and yet another to get to and work in space.. so, 3 different kinds of engines, all needing to provide sufficient and symmetric thrust.. I, for one, would like spaceplanes to be feasible. I assume people have made them with AJE so I know they're not impossible, but I'd still like that level of realism to be left to mods. High-performance turbojets is an acceptable break from reality for me, personally.

Indeed, designing and flying a spaceplane is such a rewarding (if "unrealistic", but no more than many other aspects of this game) part of KSP, it would be a shame if a major nerf of the atmospheric engines made them impractical or impossible. With regards to any changes made, be it in stock or FAR, one should ask:

1)Should an SSTO spaceplane with a significant payload be possible?

2)Should an SSTO spaceplane be capable of operating beyond LKO be possible?

3)Should an interplanetary SSTO be possible?

I don't know about stock, but with my (limited) experience of the latest version of FAR and its much higher drag at altitude (using stock parts): 1) is still possible; 2) is possible with a relatively small payload and 3) is impractical without refuelling in orbit. In all cases, your payload has to be a certain size and shape to fit inside a cargo bay, or you pay a high penalty in drag.

I personally find this is a good balance of fun vs. difficulty. Give me an engine, or a combination of engines that make his possible and I will be quite happy.

What do you guys think a spaceplane should be allowed to do?

[PB666]

^ This.

People use them in landers, but if they did the math they would find that nukes aren't the best option for the job. They are ideal for interplanetary travel and they should be.

I would like to see them require specialized heavy and expensive fuel tanks though; ones that cannot be filled using kethane.

Best,

-Slashy

This logic has problems, to optimally exploit the mun requires 2 cap, 2 mat st. and 2 goo per biome, if one does the mat to optimize sci. per landing, and opts for 2 or three hops per landing then the weight of the LV-N is less critical. 48-7S is great for its weight but its basically a flag-planting engine (best places to land and need to plant flags for their science lander to follow), but when the payload is also heavy, you really need ISP.

The problem LV-N in science landers are the non-payload parts needed to stabilize the beast on the ground. I got around this problem by making a pancake elliptical fuel tank the superstructure of the craft and placing everything bilateral of the engine, scale modded MGS for gear.

If you go for an out-of-the box lander, then you many need 15 to 30 missions to get all the sci from the Mun. If you think outside of the box you can do the mun in 5 without needing a rover or carry around science stuff on your back. Then you simply keep one kerbal on a site to plant flags for $. Plant and pull, plant and pull . . . . . .

[Jouni]

What do you guys think a spaceplane should be allowed to do?

They should be more capable than SSTO rockets, but less capable than two-stage rockets.

[PB666]

Indeed, designing and flying a spaceplane is such a rewarding (if "unrealistic", but no more than many other aspects of this game) part of KSP, it would be a shame if a major nerf of the atmospheric engines made them impractical or impossible. With regards to any changes made, be it in stock or FAR, one should ask:

1)Should an SSTO spaceplane with a significant payload be possible?

2)Should an SSTO spaceplane be capable of operating beyond LKO be possible?

3)Should an interplanetary SSTO be possible?

I don't know about stock, but with my (limited) experience of the latest version of FAR and its much higher drag at altitude (using stock parts): 1) is still possible; 2) is possible with a relatively small payload and 3) is impractical without refuelling in orbit. In all cases, your payload has to be a certain size and shape to fit inside a cargo bay, or you pay a high penalty in drag.

I personally find this is a good balance of fun vs. difficulty. Give me an engine, or a combination of engines that make his possible and I will be quite happy.

What do you guys think a spaceplane should be allowed to do?

I think the possibility issues with jet and LV-N are limited in reality because of the safety issues. NASA could save a ton by placing their launch site on top of kilamanjaero, but then how feasible is it to place stuff on an equitorial volcano. The LV-N is a risk to everything on the eastern seaboard of the U.S. and can you imagine how risky is would be to launch space craft with jets as the launch stage. Not everything that on paper looks efficient proves to be efficient in its implementation.

Consider highspeed rail versus airlines, in theory highspeed rail should far outstrip an airline in terms of profit, in reality HSR with an abundance of passangers tend to break-even or loose money relative to airlines.

[KerikBalm]

People are really missing the boat on solar sailers and currently the biggest nerf on that strategy is effing lag and part-count because we have no large xenon tanks... but whatever. I have faith that will be solved at some point.

That is easily remedied by simple modding.

https://scontent-a.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/1555368_10102995132033223_2768149624041386113_n.jpg?oh=43c5ba61ba181cc96cb7be0804c56a47&oe=5563203F

Note the grey thing behind the orange tank, and the resource panel showing tons of Xenon gas.

I simply duplicated the xenontank .cfg file, changed the mass, resources, and cost, and then set the rescale factor higher (I think it was 4... I don't recall at the moment). Uses the same texture file, so adding parts in this way doesn't affect memory usage much.

But yea.... turbojets are ridiculously OP.... nerf their fuel use, nerf their max speed.

48-7s... OP in relation to other engines... the mass optimal engine charts demonstrate this quite well

LV-N... its ISP is "realistic"... corresponding to an exhaust velocity of 8,000 m/s which is what the real NERVA acheived... but if 1 kerbo-meter= 10 human-meters... then the ISP is way too high... but then that would make gravity about 98 human-meters/s/s instead of 9.8... so its hard to really compare

-but basically, the dV needs in the Kerbin system are much smaller than real life, and an engine with real life stats would be OPd...

http://en.wikipedia.org/wiki/Space_Shuttle_main_engine

3.5 ton engine, produces 2,279 kN, so about 1.7x the TWR of the KR-2L engine (the highest TWR engine in the game, excluding the "massless" thrusters), and a vacuum ISP of 452s.

Then there is the tank:

http://en.wikipedia.org/wiki/Space_Shuttle_external_tank#Super_Lightweight_Tank

A 28.7 :1 Full: empty mass ratio... the best tanks in the game have a 9.33: 1 mass ratio

So... "realistic" values are not a reason to keep it in game.

But other than the ISP the LV-N has an abysmal TWR compared to what was developed in real life... so it seems fine (buf if the best chemical rockets are 390 instead of 452, then I think it would be fair to reduce the LV-N ISP down to about 690...)

But as far as gamplay... its fine. Yes, if you want to do an interplanetary transfer, it is the engien to use? so? is there something wrong with each engine being specialized for a given task?

We can imagine multiple flight regimes:

* Atmospheric flight - with oxygen: Air breathing engines are best

* Atmospheric flight - without oxygen (Eve): Aerospike should be best, or at least engines with higher atmospheric ISP (like the 25x4 with 320 atmospheric ISP instead of the KR-2L with 280 ISP) -> but its not, the 48-7s is because if the TWR, and for sufficiently big rockets, the KR-2L is. I hate to say it, but I think the KR-2L is OP in addition to the 48-7s, even though my FAR SSTOs make heavy use of it

* Ascent/Descent on higher gravity bodies without significant atmosphere (Duna, Tylo, Mun, Val, Moho... etc)-> a chemical rocket with a decent thrust, and good vacuum ISP is best.

* Low TWr maneuvers, like interplanetary burns, and landing on low gravity worlds (minmus, bop, pol, val, etc)-> LV-Ns, Ions are best... Im not sure about the landing part.

The LV-N already has drawbacks that give you reason to use other engines... A low TWR, a tall profile, and bad atmospheric ISP.

The tall profile results in serious design compromises for landers, or a significant risk of tipping (or part clipping).

But everythng else.... it could be like we only have 5 engines in the game:

Turbojets for the atmosphere

KR-2L for large rockets

48-7s for smaller ones

LV-N for orbital maneuvers

Ions for orbital maneuvers on small craft.

I'd like to see more uniformity in engine performance, and you basically pick between a small ISP spread (like 320-360 for the main sail), or a larger ISP spread and low weight (like 270-390 for the poodle).

So take the rockomax lineup, nerf the Skipper atmo ISP down to 310... and then make that be the basis for the 1.25, the 0.625, and the 3.75 m engines.

[LordFjord]

Game breaking engines? I think actually that there are none.

Are there balance issues with some of them? Sure, but not game breaking.

Just take a look at spacecraft exchange at some vessels, do they all use the same engines? Nope.

Of course there are cases where the power of an engine type is used to create something impressive or unexpected, like wingless jet lifters with ridiculous payload fractions, but that's perfectly fine in my opinion cause it has its own engineering and piloting pitfalls and it's usually not what the "normal" KSP player - if such a thing exists - would do.

And Squad is looking at the stats in the scope of the 1.0 release, I am pretty sure they know that things like 48-7S, nukes and jets need a closer look.

[Frozen_Heart]

tbh is the LN-N is nerfed to be balanced vs chemical engines I'll just change the config back in my game.

I really don't get the point of having an end of tech tree, high tech engine being balanced against chemical rockets.

[Laie]

LV-Ns on landers:

This logic has problems, to optimally exploit the mun requires 2 cap, 2 mat st. and 2 goo per biome, [...]

If you go for an out-of-the box lander, then you many need 15 to 30 missions to get all the sci from the Mun.

Yeah, that's one thing the efficiency-mongers tend to forget. My Labrover recently visited every biome in the Joolian system (pic, pic). Launch cost was 600k or something. Dedicated landers would drive up the part count and make for a more complicated mission. Much more complicated. And I'm not even sure if they could save a lot of money: science gear is expensive, re-using the instruments justifies a lot of extra fuel.

Nukes made that possible. I'm a bit torn whether madness like this should even be allowed.

[GoSlash27]

Indeed, designing and flying a spaceplane is such a rewarding (if "unrealistic", but no more than many other aspects of this game) part of KSP, it would be a shame if a major nerf of the atmospheric engines made them impractical or impossible. With regards to any changes made, be it in stock or FAR, one should ask:

1)Should an SSTO spaceplane with a significant payload be possible?

2)Should an SSTO spaceplane be capable of operating beyond LKO be possible?

3)Should an interplanetary SSTO be possible?

I don't know about stock, but with my (limited) experience of the latest version of FAR and its much higher drag at altitude (using stock parts): 1) is still possible; 2) is possible with a relatively small payload and 3) is impractical without refuelling in orbit. In all cases, your payload has to be a certain size and shape to fit inside a cargo bay, or you pay a high penalty in drag.

I personally find this is a good balance of fun vs. difficulty. Give me an engine, or a combination of engines that make his possible and I will be quite happy.

What do you guys think a spaceplane should be allowed to do?

A spaceplane should be "allowed" to do anything the player can make it do. The issue isn't with spaceplanes, it's with the engines, particularly the turbojet.

They're simply too powerful, efficient, and cheap for any rocket to compete with, even in the heavy lift role. They are capable of achieving payload ratios over 100% and orbiting them at $30 per tonne.

With the aero rework coming down, there's no reason why spaceplanes shouldn't work with severely nerfed air breathing engines. The engines themselves just shouldn't be better rockets than actual rockets.

Best,

-Slashy

[numerobis]

I'm curious how you define payload fraction so that it's possible to exceed 100%...

I find it fun to make basic-jet SSTOs. It's a very different challenge than a turbojet SSTO: more about pushing you up to a high altitude than about maximizing your speed. Which is what real-world jet-assist is about, too.

[UnusualAttitude]

A spaceplane should be "allowed" to do anything the player can make it do.

And what the player can make it do is heavily dependent on the performance of the engines powering it, which was the point I was trying to make ;-)

We're speaking different languages here as I'm a FAR user, so I can't contradict you about the OP nature of turbojets in stock. But I'm interested in the stock aero revamp and its consequences as ideally, I'd like not to have to mod my game for more realistic aerodynamics.

For engines, your recent proposition of a ramjet is certainly a step in the right direction, but as a casual player, I find the prospect of having to use three engine types to get a spaceplane to orbit rather daunting.

A real-life, proposed design for a SSTO spaceplane such as Skylon has a payload fraction of less than 5% to LEO. Is this what people want? I'm just wondering...

Respectfully, UA

[GoSlash27]

I'm curious how you define payload fraction so that it's possible to exceed 100%...

"Ratio", not "fraction". That is to say, the mass of the payload exceeds the mass of the launch vehicle itself. As an SSTO, no less!

A turbojet mass lifter is capable of lifting an exact duplicate of *itself* into orbit.

Best,

-Slashy

- - - Updated - - -

And what the player can make it do is heavily dependent on the performance of the engines powering it, which was the point I was trying to make ;-)

We're speaking different languages here as I'm a FAR user, so I can't contradict you about the OP nature of turbojets in stock. But I'm interested in the stock aero revamp and its consequences as ideally, I'd like not to have to mod my game for more realistic aerodynamics.

For engines, your recent proposition of a ramjet is certainly a step in the right direction, but as a casual player, I find the prospect of having to use three engine types to get a spaceplane to orbit rather daunting.

A real-life, proposed design for a SSTO spaceplane such as Skylon has a payload fraction of less than 5% to LEO. Is this what people want? I'm just wondering...

Respectfully, UA

UA,

As a user of FAR, you've seen first hand that SSTO spaceplanes don't actually require ludicrous engines to work once the aerodynamics are fixed. FAR nerf-clubbed the jets like baby harp seals, and rightfully so. They now work very well as jet engines and make lousy rockets, but SSTOs still work despite all that.

Wanderfound even has interplanetary SSTOs in FAR.

Best,

-Slashy

Edited February 2, 2015 by GoSlash27

[Laie]

"Ratio", not "fraction". That is to say, the mass of the payload exceeds the mass of the launch vehicle itself. As an SSTO, no less!

A turbojet mass lifter is capable of lifting an exact duplicate of *itself* into orbit.

More. I just did one for the Payload Efficiency Challenge:

66 tons of SSTO (including fuel) lifting a 144t payload to orbit. At 15 funds per ton. And I'm pretty sure that this is not the end of the line.

[KerikBalm]

I just made a FAR SSTO with a payload fraction of 21%... that is, the payload weight was 21% of the combined SSTO+ Payload weight on the runway.

The payload was 122 tons. Nerfed jets don't kill spaceplanes... assuming FAR level nerfs

If you calculate it his way where over 100% is possible, then I guess it would be 21/79 = 26%

I think I could have done a lot better ascent, I was getting impatient and lit the rockets at 22km and only 1100 m/s. I'm sure I can do better with the design (and I tweaked the design because it had a few issues with the CoM and CoT in rocket mode that made it hard to fly)

That was with an external payload.

I madea mk3 spaceplane that lifted a 40t cargo, I think that one was 160 tons with the payload (40/160 = 25%... or 40/(160-40) = 33% )

In stock career.... I just did direct turbojet ascents.... seemed cheaty- but it was cheaper which meant less grinding for cash to upgrade buildings.

[GoSlash27]

I just came up with a funny way to "nerf" the LV-N without actually nerfing it:

Every time you use it, you take a reputation hit (the amount decreases with successful missions). If you have a mishap with one or ignite it in Kerbin's atmosphere, you take a bigger reputation hit.

This would reflect the Kerbals' negative opinion of nuclear propulsion similar to the public opinion here on Earth.

Best,

-Slashy

- - - Updated - - -

More. I just did one for the Payload Efficiency Challenge:

66 tons of SSTO (including fuel) lifting a 144t payload to orbit. At 15 funds per ton. And I'm pretty sure that this is not the end of the line.

^ 2 copies of itself

Amazing what you folks are accomplishing over there!

Best,

-Slashy

[Renegrade]

This logic has problems, to optimally exploit the mun requires 2 cap, 2 mat st. and 2 goo per biome, if one does the mat to optimize sci. per landing, and opts for 2 or three hops per landing then the weight of the LV-N is less critical.

You don't actually need to do crap like that. That's ridiculous. You're getting something like 75%-85% of the science with just one of each (and you can transmit a surface sample and then pick up another to cheaply enhance returns). I used to have a complex flag-labeling system where I'd track which experiment was used where, but then I realized that was a vast waste of time, and I just plant one flag to avoid returning to that spot, regardless of what science I'd gotten there.

100% science from an area (and doubling up the items isn't 100% either by the way, it's using a diminishing return/floating point system. It would take literally hundreds of items per biome to underflow that to zero) is completely unnecessary to complete the tech tree in Kerbin's SOI even before contracts and massively broken strategies.

Then you simply keep one kerbal on a site to plant flags for $. Plant and pull, plant and pull . . . . . .

Last I checked, the flag missions aren't offered if you have a manned craft on the surface in 0.90.

[metl]

Last I checked, the flag missions aren't offered if you have a manned craft on the surface in 0.90.

Well that explains a lot of things... I just thought I was getting really bad draws!

[Pthigrivi]

Yeah if anything science needs a big overhaul. I know they want to take the grind and clickiness out and I think making experiments both more involved and more rewarding will do that. You should really feel like you're going somewhere and doing something rather than just harvesting.

[Renegrade]

Well that explains a lot of things... I just thought I was getting really bad draws!

Yeah, it was a surprise for me too. "Why am I NOT getting a Duna flag planting mission anymore?". Then I saw this in the Fine Print thread as part of the 0.90 changelog:

* Unless it is your first flag on a planet, flag contracts will no longer appear for planets that have Kerbals on them already. Once the kerbals move off of the planet, they will appear again

It makes sense-ish, to avoid easily grinding 'em. You could probably bypass it with a short sub-orbital hop..at the risk if not returning in time to save the kerbal from auto-deletion

Yeah if anything science needs a big overhaul. I know they want to take the grind and clickiness out and I think making experiments both more involved and more rewarding will do that. You should really feel like you're going somewhere and doing something rather than just harvesting.

Yeah, I agree - there's been some pretty good suggestions on these forums here or there for overhauls of the science system. Whatever Squad does, I hope it encourages leaving Kerbin's SOI..

[RobotsAndSpaceships]

All the radial engines, way too high thrust.