(need advice) For Spaceplanes, What Counts As "Cheaty" exactly?

[quasarrgames]

I have a good understanding of Ksp spaceplanes and i have made a lot of them. However after perfecting the art of extreme airhogging with 30-ram-intake-to-1-turbojet spaceplanes, I am now challenging myself to make realistic (or at least not cheaty) spaceplanes.

However that's where i'm stuck. I don't know what exactly counts as cheaty. I am looking for advice on what is cheaty and what is not, specifically on intake-to-turbojet ratios, but also on things like wing and control surface clipping.

Edited March 12, 2014 by quasarrgames

[wasmic]

Generally, minor part clipping (far aesthetics) is not cheating, but major part clipping, like placing identical fuel tanks on top of each other, is cheating. At least, that's how I see it. And I'd generally say that more than three, or maybe four, intakes per turbojet would be classified as airhogging.

[cantab]

"Realistically" there'd be one intake per engine. Maybe two with some single-engine designs.

[Behemoose]

Here's one I just built:

Completely stock, no clipping at all, only two radial intakes, and it uses almost no rocket fuel at all to reach orbit. Flight profile makes the difference, in my opinion.

Oh, and here's an airhog I mess around with:

As a general rule, if it's not possible or workable with a real aircraft, it feels cheaty to me.

Edited March 11, 2014 by Behemoose

[Jouni]

A kind of realistic approach to intakes would start with considering air flows inside the plane. If the line of air flow from intake to engine is too far from the line of thrust from the engine, that intake would cause excessive drag. Of course the parts between the intake and the engine should allow air flow in the first place. I would assume that cockpits, jet fuel tanks, and solid structural parts have suitable air ducts, while other fuel tanks, girders, struts, and wings don't. (Jet fuel tanks have much lower mass than rocket fuel tanks of similar size, so they probably have a lot of empty space.)

[Taki117]

Generally speaking, if it looks realistic go for it. My SSTO Discovery has an intake ratio of about 2.5 to 1, but because of how it looks this isn't very cheaty at all. IT has since changed designs since this pic, but the engine/intake layout remains unchanged.

[Kasuha]

Eveybody has their own opinion of what is and what isn't cheating in KSP. It's a single player game so the only person on which you may be cheating is you.

Not using the debug menu is one of more widely recognized standards for "not cheating", although when talking about clipping, there is a whole lot of it that can be done without debug menu.

Anything above that is pure up to your choice.

[Claw]

I have a good understanding of Ksp spaceplanes and i have made a lot of them. however after perfectiong the art of extreme airhogging with 30-ram-intake-to-1-turbojet spaceplanes, I am now challenging myself to make realistic (or at least not cheaty) spaceplanes.

However that's where i'm stuck. I don't know what exactly counts as cheaty. I am looking for advice on what is cheaty and what is not, specifically on intake-to-turbojet ratios, but also on things like wing and control surface clipping.

I'm sure you will get a wide variety of responses. I see nowhere in your post about "realistic" which is probably good because realistic KSP is not, and I'm not just talking about all the complaints about the aerodynamic model.

What I mean is that your typical airplane doesn't fill the fuselage with fuel, it fills the wings. There may also be tanks inside the fuselage, but it depends on the plane. Also, the compressor section of intakes are always inline with the engines. The only parts of intakes that don't have to be inline would be the actual inlet and ducting. Also, most planes don't duct hot intake air through a fuel tank (i.e. putting an intake on the front of a Mk-1 with an engine on the back). I can continue on but like I said, a bit of realism needs to be suspended for KSP (or just about any game for that matter).

In either case as far as "cheaty" goes, my personal opinion is that is entirely up to you. I can share my own cutoffs for you, but with an open ended game like KSP cheating is all relative.

That being said, 30:1 intake ratio seems very excessive to me. I typically aim for about 3:1, but certainly you can even get away with 1:1. In my experimenting, I found that going past 3:1 starts to degrade things I care about (such as time). It also gets to the point where you have to start doubling the intakes to get much performance increase. So the next descent step after 3:1 is 6:1, then 12:1. So that's really what I based my 3:1 decision on (rather than arbitrarily picking a number). Either way, there is no strict definition of "air hogging" and it becomes a matter of someone looking at a design and saying, "Holy cow, look at all those intakes!"

As for clipping, I usually only do what the editor allows me to get away with. With maybe the exception that I won't try to fold tanks back in on themselves. Some fuel tanks will let you do that, even with the default editor clipping. I guess I avoid things that are physically unrealistic, but you could justify just about any design choice. Most of the other clipping I do is for cosmetics, such as using the tail boom fuselage piece to blend an engine or intake into the side of a fuselage. Again, any level of "cheating" is really what limitations you care to impose upon yourself (or what the Kraken will impose on you).

Edit: Ninja'd by Taki and Kasuha. At least I agreed with them.

[Jouni]

What I mean is that your typical airplane doesn't fill the fuselage with fuel, it fills the wings. There may also be tanks inside the fuselage, but it depends on the plane. Also, the compressor section of intakes are always inline with the engines. The only parts of intakes that don't have to be inline would be the actual inlet and ducting. Also, most planes don't duct hot intake air through a fuel tank (i.e. putting an intake on the front of a Mk-1 with an engine on the back).

Technically, parts such as the Mk1 Fuselage are fuselage parts, not fuel tanks. The Mk1 has 40% more dry mass than the similarly sized FL-T400 Fuel Tank, while its fuel capacity is only 37.5% of the FL-T400. Because of that, I find it quite reasonable to use the fuselage parts for similar engine configurations as in fighter jets.

As for realism, the small scale of KSP doesn't work as well with spaceplanes and other reusable ships as with traditional rockets. In most real-world spaceplane proposals, rockets do the bulk of the work, while airbreathing engines are used at most to get the plane out of the thickest part of the atmosphere. You can simulate this in KSP to some degree by using basic jets instead of turbojets, which also makes spaceplane design much more challenging.

[Claw]

Technically, parts such as the Mk1 Fuselage are fuselage parts, not fuel tanks. The Mk1 has 40% more dry mass than the similarly sized FL-T400 Fuel Tank, while its fuel capacity is only 37.5% of the FL-T400. Because of that, I find it quite reasonable to use the fuselage parts for similar engine configurations as in fighter jets.

I guess what I'm trying to say is if you look at fighter jet designs, they don't usually wrap the engine's compressor section with fuel. In my mind, the ram/circular intake is the compressor section. This may not be what KSP intends at all, but that's what my comment was based on.

This is a different view than if the ram/circular intake is simply an inlet. In which case ducting is less of a problem. (Which is also what I said.)

Regardless, I'll take the simplistic KSP approach to having overly complex build rules. In my opinion, being able to put something like intakes anywhere, while maybe not "realistic," makes for more diverse designs.

[Hodo]

Cheaty is what you make of it. I personally feel running the stock KSP without FAR+DRE is cheaty. Here is my heaviest lifter SSTO space plane before I added RSS+RF to the mix.

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And here is my newest SSTO space plane in the Real Solar System with Real Fuels sized Kerbin (which makes it the same size as Earth).

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Most of my craft are 3:1 intake to jet ratio at max. I haven't found a real life example of an aircraft with more than 3 intakes per engine.

[SSSPutnik]

With 0.23 and FAR two intakes is usually sufficient.

[Amaroq]

Heh. Yeah, my answer would be "Install F.A.R. Anything that stays airborne is not-cheaty."

Note that I have yet to master "staying airborne" with F.A.R. ...

[Taki117]

Heh. Yeah, my answer would be "Install F.A.R. Anything that stays airborne is not-cheaty."

Note that I have yet to master "staying airborne" with F.A.R. ...

As a FAR user I must say if it looks like it could fly, it will. (My space plane posted above routinely makes a 200kmx200km orbit). If OP does decide to install FAR (highly reccomended) then they should focus more on making it fly first, then worry about getting to space.

[quasarrgames]

Thanks for the advice, everyone. Because of you guys now i think i have an understanding of what is cheaty and what isnt:

It is best to have only one intake per engine, but having up to three intakes per engine is fine.

And the air intakes should not be clipping, and nether should the control surfaces. They should be realistically placed.

did i get any of these wrong?

I may get far, but first i need to figure out how it will affect my other rockets, since i have no faring mods. Real scale kerbin is a bit out of the question, though. i dont have nearly the expertise to make an ssto, let alone a rocket that could even get into orbit with it.

thanks again!

[cyberklad]

There is a huge diffrence between b9 intakes and the stock intakes. any of the b9 intakes take in a lot more air then the stock ones do. And if you take some of the larger intakes in the b9 pack you need at least 5 stock ram intakes to match it. So in that regard the b9 intakes can be seen as cheaty too.

Air hogging is an oddity that is created by how KSP handles jet engines. It's a bit sad that they have an intercooler part and have not implemented the actual use of such a part. After all. the challenge with jet engines is not getting enough air for the engine. But rather getting the air cold enough to be used in the combustion process.

[Claw]

Thanks for the advice, everyone. Because of you guys now i think i have an understanding of what is cheaty and what isnt:

It is best to have only one intake per engine, but having up to three intakes per engine is fine.

And the air intakes should not be clipping, and nether should the control surfaces. They should be realistically placed.

did i get any of these wrong?

Those are probably generally accepted with the community, but I still must say that it depends on you. If you feel those are reasonable limitations, then stick with them. For me personally, intake clipping is okay.

It's a bit sad that they have an intercooler part and have not implemented the actual use of such a part. After all. the challenge with jet engines is not getting enough air for the engine. But rather getting the air cold enough to be used in the combustion process.

This may be slightly misleading. The intercooler helps high speed (mach 3+) engines improve efficiency. Cooler air improves performance because of density, but for nearly all TurboJets (or high bypass turbofans), precooling isn't required for combustion.

[quasarrgames]

[quote name=Claw;

This may be slightly misleading. The intercooler helps high speed (mach 3+) engines improve efficiency. Cooler air improves performance because of density' date=' but for nearly all TurboJets (or high bypass turbofans), precooling isn't required for combustion.

Are you talking about in game, or irl? if you mean in game, i need to chock a load of those on my sstos! I thought they were just aesthetic parts that were meant to have a use but didnt.

[sjwt]

Cheaty is whatever YOU feel is cheering. Don't fall into the trap of trying to play KSP to meet others expectations.

[Claw]

Are you talking about in game, or irl? if you mean in game, i need to chock a load of those on my sstos! I thought they were just aesthetic parts that were meant to have a use but didnt.

Real life. Actually I haven't tried them in this manner in game as I had assumed they weren't really implemented yet. Might be worth trying out just to see.

[ThermalShark]

Real life. Actually I haven't tried them in this manner in game as I had assumed they weren't really implemented yet. Might be worth trying out just to see.

They are completely just aesthetic and structural. That's what the wiki says, and by looking at its config file it can be proven it does not provide funcionality like that. It isn't even possible to have a part with that functionality without mods.