Ion Hovercraft on Mun. Possible to achieve?

[automcdonough]

I've just been trying to produce an effective Really Long Range Ion Mapping Probe.

So far, the results have been disappointing, either it runs at full power but I don't get more than 3000 dV, at which point I'm better off with liquid fuel to do what I set out to do, or it has 6000 paper dV but every attempt to make use of it wastes most of it on burns it can't actually complete.

I know it's not the most weight efficient but one big panel is pretty easy to run it continuously. 2 or 3 tanks and it's easy 6000+ d/v

Plus I think they look simple and cool.

[RawChicken]

Here, try this calculator i made

http://forum.kerbalspaceprogram.com/showthread.php/28177-Ion-engine-launch-capable-calculator-I-did

[Mihara]

I know it's not the most weight efficient but one big panel is pretty easy to run it continuously. 2 or 3 tanks and it's easy 6000+ d/v

Plus I think they look simple and cool.

As you pile on tanks, your TWR goes further and further down. Just about after the second tank, using it becomes a pain because burn times become way too long.

10 of 1x6 solar panels work better, but I'm still not happy with the results. The smallest solar panels are by far the most weight efficient, but getting them into an effective arrangement is considerably more complicated.

[Piggius_Max]

Could a seat, xenon gas and a few batteries do it for minmus? You'd need a separate craft for collecting the electricity to charge it :/

[protoz]

Could a seat, xenon gas and a few batteries do it for minmus? You'd need a separate craft for collecting the electricity to charge it :/

Ya minmus shouldn't be any problem, although you probably don't want to spam batteries, thats a Mun thing for unsustainable hovercraft which i have .craft in this thread. You want to cancel out your power consumption instead of battery spam.

On sidenote, I've just completed the Dres hovercraft. 1hour 12 minutes, sustained flight, has seats & docking port so you can recharge it and impossible not to land correctly.

Edited May 27, 2013 by protoz

[protoz]

Could a seat, xenon gas and a few batteries do it for minmus? You'd need a separate craft for collecting the electricity to charge it :/

Also with seat + xenon gas + 1 ion engine & not counting anything else. You can only add up to .089 mass for it to hover.

[Mihara]

...That gives me an idea of a KAS-based ion kite.

A rover with batteries, panels/RTGs, and a winch on the ground, and a seat with ion+xenon connected by the cable for power floating behind it.

...I want KAS back.

[protoz]

This is how a ion 1hour hovercraft for Dres looks like.

[DMagic]

Could a seat, xenon gas and a few batteries do it for minmus? You'd need a separate craft for collecting the electricity to charge it :/

I made a manned Minmus ion lander, so a hover craft should be no problem. I even used the gigantor panels, more efficient solar panels should make it even easier. I have a mission report thread for this. I did Bop, Pol, Gilly, Ike and Minmus, I got bored before I tried Dres and I couldn't get a high enough TWR for the Mun.

[protoz]

I made a manned Minmus ion lander, so a hover craft should be no problem. I even used the gigantor panels, more efficient solar panels should make it even easier. I have a mission report thread for this. I did Bop, Pol, Gilly, Ike and Minmus, I got bored before I tried Dres and I couldn't get a high enough TWR for the Mun.

Mun's not possible the .craft file in this thread for Mun is the best thing you can optimize.

[DMagic]

Mun's not possible the .craft file in this thread for Mun is the best thing you can optimize.

Yeah, that's what I figured. The mass of the engine plus the solar panels needed to power it is too much for the Mun. I tried some of the bigger, more efficient Kosmos panels, but they were too heavy, too.

Another thing to keep in mind about these ion engine crafts is that the in-game description lies about the electricity requirement. It says 12 E/sec, but it should be more like 14.5 E/sec, unless they changed it for .20. That small difference has a huge impact when trying to come up with these kinds of designs.

[protoz]

Yeah, that's what I figured. The mass of the engine plus the solar panels needed to power it is too much for the Mun. I tried some of the bigger, more efficient Kosmos panels, but they were too heavy, too.

Another thing to keep in mind about these ion engine crafts is that the in-game description lies about the electricity requirement. It says 12 E/sec, but it should be more like 14.5 E/sec, unless they changed it for .20. That small difference has a huge impact when trying to come up with these kinds of designs.

I got the Dres craft complete but i can't test it as soon as i hyperedit it w. <1 FPS (590 parts) it starts a spasm and blows up, & w. unbreakable joints on it won't stop going crazy. I think this concludes my ion testing, which is limited by this game's engine as it cuts off the ability to create crafts i want to create as they are severely limited by part count which cause unplayable fps & kraken spasms.

Also one other thing that frustrates about electricity in this game is there is no middle ground. Lights, probe bodies, wheels, science modules require next to nothing, while ion engines being nearly obsolete require insane amounts.

Heres the Dres hovercraft if anyone wants to give it a test, cause i wasn't able to.

https://mega.co.nz/#!SMIz0SZZ!PBrHQ2tP4gdxa4tuvPPw23qrsd5bksNsFtPLiqHCqvw

I might over overkilled it for Dres one w. 24 ion engines, im gonna revert back to 16 as i used for the Mun one and go from there, 590 parts is just too much for this game.

Edited May 27, 2013 by protoz

[Mihara]

Another thing to keep in mind about these ion engine crafts is that the in-game description lies about the electricity requirement. It says 12 E/sec, but it should be more like 14.5 E/sec, unless they changed it for .20. That small difference has a huge impact when trying to come up with these kinds of designs.

It doesn't exactly lie, more like, you're expecting the text to mean something that it doesn't mean, and by oversight, it isn't immediately clear. It doesn't list "electricity requirement", but lists a "fuel consumption ratio". I.e. for every X units of xenon consumed, Y units of electricity will be consumed, and electricity is not a constant power drain in this case, but a fuel. Actual fuel consumption also depends on engine ISP and throttle level.

And it turns out that at full throttle, the per-second consumption does come out to higher than 12 E/sec.

[Sliinty]

I've done some rudimentary maths, (not going to bore you with too much working) I don't think its possible with the power density of stock solars and the TWR of stock ion drives

The highest achievable electricity/second/ton in stock is 150 (from the smallest solars with no structure). The surface gravity on the mun is 1.63.

So lets assume that you have so many engines per tank of xenon that the mass of the xenon tanks becomes negligible, and your craft is so big the mass of the probe also becomes negligible, your free mass (mass that isn't engines) is

0.0567*n=m

where n is number of engines, m is mass, and the mass of a solar array to power a given number of engines is

m=12*n/r

where r is your elec/second/ton

so combining those 2 equations,

r=0.0567n/12n=211.5

...which is quite a bit higher than the maximum possible ratio. (150)

And not to mention we have an infinite number of engines per tank and a massless probe body and a massless structure holding the solars in place to give us 150.

But its pretty easy on minmus http://forum.kerbalspaceprogram.com/showthread.php/30329-Ion-Engines-Everywhere-My-Attempt-to-Land-As-Many-Places-As-Possible

EDIT: apparently Ion engines actually use 14.5 e/s not 12, so the required ratio is actually 255.73... even further beyond the realms of possibility

Edited May 27, 2013 by Sliinty
incorrect stats

[Sliinty]

And for purely unsustained flight its around 78s, hybrids are obviously the way to go, but the theoretical max for them is harder to work out