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Cyro
United Kingdom20344 Posts
Don't stack ion engines like that, that would increase the mass more than it increases the thrust with a heavy craft you can double the number of ion engines +fuel without doubling the mass, you get more TWR and more delta-v - but i see it's hard to do anything useful with them on heavy craft :D | ||
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nimbim
Germany986 Posts
On April 10 2015 13:11 Cyro wrote: with a heavy craft you can double the number of ion engines +fuel without doubling the mass, you get more TWR and more delta-v - but i see it's hard to do anything useful with them on heavy craft :D Increases mass, increases thrust and decreases efficiency. The decrease is so immense that it really isn't worthwhile to do. http://www.strout.net/info/science/delta-v/ Every additional ion engine will increase the total mass and dry mass by 0.25t - this is essentially dead weight. If you want to try some numbers the larger xenon tank has 0.07t of fuel and ion engines an Isp of 4200s. | ||
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Cyro
United Kingdom20344 Posts
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Cyro
United Kingdom20344 Posts
![[image loading]](http://i.imgur.com/khumxex.jpg) | ||
Epoxide
Magic Woods9326 Posts
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Cyro
United Kingdom20344 Posts
and lol not really any slow climbing - just abusing intake spam and the insane efficiency of air breathing engines around 15-25km. That thing went FAST to the point where i had to pull up way harder than i wanted to due to air resistance and re-entry flames four turbojets and four rapiers firing at once with some fuel tanks to discard My biggest problem is losing half of the ship mass on the way up (and particularly, when using jet engines) because i'm eating all of the fuel, and then on the way back down the center of lift vs mass is probably horribly set up and the whole plane feels like paper and goes into wild spins with almost no provocation (but that happened to everything that i put into orbit, spent fuel with and then came back down using..) maybe i should just add fuel tanks on decouplers, leave the liquid fuel as the core body of the plane and decouple the liquid+oxidizer mixed tanks - anything plane-like that i build is just spinning like a top and getting thrown everywhere with way more force than i can reasonably counteract and if/when i stabilize it on the way down, it's then really awkward and hard to fly | ||
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Jetaap
France4814 Posts
 .Anyway, no matter what you do getting into orbit from kerbin is going to take a lot of fuel, once you're in space you need very little fuel comparatively to manoeuver. | ||
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Cyro
United Kingdom20344 Posts
The abuse is because you spammed air intakes in order to be able to use jet engines at higher altitude that you should be able to . Isn't that what everyone does?  You need to double intake to fly like 3.5km higher. There's no penalty for stacking intakes so i don't see a problem with running 4x as much intake to get that last 7km, it's really important :D Anyway, no matter what you do getting into orbit from kerbin is going to take a lot of fuel, once you're in space you need very little fuel comparatively to manoeuver. Yeah, but i have like an hour of fuel in atmosphere and 90 seconds of fuel when i switch engines. Even if it's 50x easier to maneuver you still run dry almost immediately | ||
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Millitron
United States2611 Posts
On April 10 2015 14:08 Cyro wrote: If they're 55% as fuel efficient but there's twice as many of them, you still go faster and further You will never go further with more than one engine once you're in space. 2 engines have the same ISP as 1, but they weigh twice as much. You will also end up faster with only one engine, as you'll have more delta V. Two engines will allow you to accelerate quicker, but your top speed will be lower. | ||
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Epoxide
Magic Woods9326 Posts
On April 13 2015 05:03 Cyro wrote: Isn't that what everyone does? You need to double intake to fly like 3.5km higher. There's no penalty for stacking intakes so i don't see a problem with running 4x as much intake to get that last 7km, it's really important :D It's just what every individual feels is okay to do. Stacking thing doesn't feel right to me, also I play with FAR anyway. | ||
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Cyro
United Kingdom20344 Posts
On April 13 2015 05:14 Epoxide wrote: It's just what every individual feels is okay to do. Stacking thing doesn't feel right to me, also I play with FAR anyway. If it's unintentional, why is it still in the game? etc if you're going to fly higher in the atmosphere, you need a LOT more intake because oxygen income drops as fast as atmospheric drag. I think that's a nice correlation but flying a plane with minimal intake would probably not really work well at all in comparison, so maybe there should be a tweak to mechanics. Overall because of the huge fuel consumption once you rely on oxidizer, i'm having trouble justifying using a spaceplane for anything even though i think they're really cool. My simpler designs got into orbit and back again, landing safely. The more complex ones got into better orbits with more fuel quite easily - but then they can't land without chutes, so what's the point? Having to shut down air engines at 22km instead of 30km just makes that issue feel much worse~ On April 13 2015 05:09 Millitron wrote: You will never go further with more than one engine once you're in space. 2 engines have the same ISP as 1, but they weigh twice as much. You will also end up faster with only one engine, as you'll have more delta V. Two engines will allow you to accelerate quicker, but your top speed will be lower. Aha makes sense, i was probably thinking about it wrong. In this case, you'd suggest adding the extra fuel but not the extra engines, right? though the higher the fuel to engine ratio, the worse acceleration rate is. Running 100 hours of fuel on 1 engine would suck, but running 5 minutes of fuel on 50 engines should also be terrible also i think it's better to lean on the side of more thrust instead of less, because that actually does benefit you for abusing oberth effect and generally applying the thrust where it's most effective | ||
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Simberto
Germany12023 Posts
The reason you use multiple engines is because you don't want to stare at your screen through a 30 minute acceleration phase. You are playing a game, and it should be fun, and watching a bar very, very slowly go up isn't a lot of fun for me. Thus i throw in enough engines to make sure that any maneuver i want to do is at most 5 minutes of acceleration. | ||
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Epoxide
Magic Woods9326 Posts
On April 13 2015 05:20 Cyro wrote: If it's unintentional, why is it still in the game? etc They are changing the aerodynamics model in 1.0. | ||
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Cyro
United Kingdom20344 Posts
On April 13 2015 05:39 Epoxide wrote: They are changing the aerodynamics model in 1.0. Any details on that? (or how it affects intakes) | ||
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Millitron
United States2611 Posts
On April 13 2015 05:38 Simberto wrote: Yeah, as i stated before multiple times, the main reason to have multiple engines is not efficiency, or even the ability to perform specific maneuvers. If you have more engines, you are less efficient, and you can perform most maneuvers in space with minimal acceleration. The reason you use multiple engines is because you don't want to stare at your screen through a 30 minute acceleration phase. You are playing a game, and it should be fun, and watching a bar very, very slowly go up isn't a lot of fun for me. Thus i throw in enough engines to make sure that any maneuver i want to do is at most 5 minutes of acceleration. I suppose there might be some certain windows where you do need a high TWR to get the maneuver right. For instance, a trip to Moho could have stupidly high velocity at your closest approach. If you use a single ion engine on a large ship, you really might not have enough acceleration to enter orbit. But they're definitely not the norm. 99% of the time, you only want one engine. | ||
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Simberto
Germany12023 Posts
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Cyro
United Kingdom20344 Posts
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Simberto
Germany12023 Posts
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felisconcolori
United States6169 Posts
On April 13 2015 06:31 Cyro wrote: How are you guys time warping while accelerating? Game won't let me go past 1x when engines are on Physical time warp is allowed under acceleration or with engines on (and the game will tell you that things may behave oddly, especially with large ships, under physical time warp greater than 2x) and I there's a key to force physical time warp. I think it's alt, ctrl, or shift, but I haven't had to use it in awhile so I'm not sure which it is. Physical time warp allows 1, 2, 3, and 4x time warping. As I mentioned above, though, large part count ships under acceleration can behave in peculiar fashion because of the stresses applied in the way that the physical time warp is handled. (Unsure of specifics, I can't tell you exactly how it works - but it involves calculating the physics and sometimes a small jiggle very quickly becomes OH MY GOD IT'S EXPLODING.) | ||
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stenole
Norway869 Posts
On April 13 2015 05:43 Cyro wrote: Any details on that? (or how it affects intakes) What I've heard so far is that drag will be modeled more like in FAR. All parts will have aerodynamic properties meaning not only wings apply lift to your craft. There will be no drag on things inside the fairings or inside cargo bays. And parts that have parts in front of them will apply much less drag. Engines and wings, all parts in general, will be rebalanced to fit the new drag model. Parts are likely to get ripped off if you put too much stress on a craft, perhaps mostly when reentering the atmosphere. Also temperature will be simulated for all parts and they will be destroyed if they get too hot. So, the main consequence I guess is that pancake rockets with asparagus staging will no longer be the way to go. Space planes from 0.90 might no longer work. You'll have to be more careful on your return to Kerbin. Maybe use and orbit or two for aerobraking before landing. If I were to guess, stacked air intakes wouldn't work anymore (but you can spam 0.90 intakes anyway without needing to have them on top of each other.) Maybe the way they work will be tweaked to make them harder to exploit. The 1.0 version is coming out pretty soon. It is currently in the experimental stage which means that people outside the development and QA team who have signed a secrecy agreement are playing it. The next stage is release. Previous experimental stages have lasted about 2 weeks. This one is estimated to last a little longer. So maybe the end of April or beginning of May. Maybe now is not the perfect time to learn exactly how the stock aerodynamics works. | ||
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