Laythe orbit using ions

[Teilnehmer]

Inspired by Dcseal’s Mun orbit challenge and Foxter’s Duna orbit challenge.

There is a large gap in the surface gravity values between the “big four” (Eve, Kerbin, Laythe, Tylo) and the other planets.

The biggest of the others, Duna, has g = 2.94 m/s². It’s relatively easy to ascend from it using ion engines only (see the link above).

Tylo and Laythe have g = 7.85 m/s². The maximum acceleration an ion engine (0.25 t) with a xenon tank (0.03 t even if empty) can deliver is 2 kN / 0.28 t = 7.14 m/s² (let alone the probe core, electricity sources and so on). This makes the challenge impossible for Tylo.

Eve, Kerbin, and Laythe have atmospheres allowing to use winged vehicles with lower TWR. On the other hand though, the atmospheric pressure kills the thrust. The Dawn engine’s output on Eve is zero, and on Kerbin it’s only 0.05 kN (40 times lower than in vacuum). This fact makes Eve and Kerbin hopeless too.

But. According to the graph, Dawn’s thrust at Laythe’s sea level is 0.71 kN (2.8 times less than in vacuum). At the Laythe’s highest elevation point, it’s 1.36 kN (only 1.5 times less than in vacuum).

So, that’s a challenge!

(No idea if it’s possible or not. I haven’t tried yet, but I’ll try.) It’s possible! Eidahlil proved that.

The goal: get into an orbit from Laythe using ion engines only.

Rules:

• No cheating
• Stock parts only, no physics mods
• Hyperedit to Laythe is allowed
• You should take off from the surface of Laythe (either solid or liquid) and get a stable orbit (Pe above 50 km)
• Dawn ion engines are the only propulsion devices, no RCS translation
• Manned, unmanned, single-staged, multistaged — whatever.
• The lower the elevation you start from the better

 

Winners:

1. @Eidahlil (here) altitude: 6050 m
   
   

Edited December 29, 2016 by Teilnehmer

[SpaceplaneAddict]

But, you have to try first! I'll go for it anyway.

[Yukon0009]

I'm pretty sure 1.0 killed off ion planes completely.

[TheGeekno72]

Can we launch a ionic vessel in LKO with a launcher before the travel ?

[Teilnehmer]

TheGeekno72 said:

Can we launch a ionic vessel in LKO with a launcher before the travel ?

It doesn’t matter how you deliver your vessel to Laythe. You can even use hyperedit.

- - - Updated - - -

SpaceplaneAddict said:

But, you have to try first! I'll go for it anyway.

I’m trying. No success yet.

Edited December 17, 2015 by Teilnehmer
Unicode mess

[xebx]

Ion engine are meant for vacuum operations, ionized gas in atmosphere is nonsense. (except in very high atmo : ionosphere, the limit of atmo/vaccum)

Not for me, but good luck !

Edited September 25, 2015 by xebx

[Foxster]

Anyone have coords for a high spot on Laythe?

Update:

I'm gonna call this one busted.

Solar cells don't make much juice on Laythe so it means using one or more fuel cells and an LF+O tank. That adds weight and drag. At no altitude could I get enough thrust for steady flight with any number of engines.

I think this one is unlikely to be possible.

Edited September 25, 2015 by Foxster

[Teilnehmer]

Foxster said:

Anyone have coords for a high spot on Laythe?

Lat: -17.5891

Lon: 172.5842

(elevation: 6 km)

Foxster said:

I think this one is unlikely to be possible.

Aha.

I can’t gain speed beyond 200 m/s and altitude above 10 km.

Edited December 17, 2015 by Teilnehmer

[Hast5250]

what about rtgs?

imma give this a try!

[Teilnehmer]

On 12/13/2016 at 4:21 AM, Hast5250 said:

what about rtgs?

Hm…

A fuel cell array has a mass of 240 kg and consumes 0.225 kg of Lf+O per second producing 18 e/s of electricity.

An RTG has a mass of 80 kg producing 0.8 e/s of electricity.

Let’s find when RTGs are lighter than fuel cells:

(80 kg) / (0.8 e/s) < (240 kg + 0.225 kg/s ∙ t) / (18 e/s)

t > 6933 s ≈ 2 hours

So, yes, if it takes us 2 hours or longer to reach orbit, the take-off mass with RTGs is lower. (But with fuel cells, we lose more mass during the flight.)

The drag is also an important thing to take into account! Maybe, RTGs have substantially lower drag than FCAs? Now, in KSP 1.2, it is possible to make long strings of stacked RTGs using autostruts to keep them from wobbling.

Edited December 14, 2016 by Teilnehmer

[Teilnehmer]

On 12/14/2016 at 0:56 PM, Teilnehmer said:

Maybe, RTGs have substantially lower drag than FCAs?

No. Actually, the drag is much lower with FCAs. Stacking doesn’t help with RTGs.

[Hast5250]

A FCA and a fuel tank is much heavier than an RTG.

[AeroGav]

This has more chance of working on Duna I'd expect.    You can fly and land aircraft on Duna, but they need generous wing area & strong landing gear.   Even at the lowest points on Duna's terrain the air pressure is low enough to get good ISP out of ions, much lower pressure than all other bodies with an atmo.

The lower gravity compared with Laythe means less drag, given lift:drag ratio constant so you should be able to acclerate and build speed/height with less thrust.

The only downside is that the thin atmosphere means you 'll have to go supersonic shortly after takeoff, i've not seen better than 4.5 to 1 at supersonic speed on any of my designs, whereas my normal sstos can make double that subsonic.   However, to make orbit you need to go  supersonic at some point, you need the installed thrust to work at supersonic l/d ratios.

How many fuel cell stacks can fit in a 2.5m service bay, provided they are shielded it should be lower drag right?

You only need enough fuel cells for sustained supersonic flight.      During the transonic bit drag is even higher , but you can probably get past that with temporary battery boost.

[Teilnehmer]

6 hours ago, AeroGav said:

This has more chance of working on Duna I'd expect.

Duna’s gravity is so low that you don’t need wings at all there. See the second link in the first post: ‘Achieve Duna orbit using only ion engines’ challenge by @Foxster.

6 hours ago, AeroGav said:

How many fuel cell stacks can fit in a 2.5m service bay, provided they are shielded it should be lower drag right?

I’ve tried implementing exactly that for Laythe. No success yet, but I still don’t lose hope.

11 hours ago, Hast5250 said:

A FCA and a fuel tank is much heavier than an RTG.

Not an RTG but 22 RTGs are needed to replace one FCA.

Edited December 18, 2016 by Teilnehmer

[tseitsei89]

6 hours ago, AeroGav said:

 

How many fuel cell stacks can fit in a 2.5m service bay, provided they are shielded it should be lower drag right?

I recommend a fairing. It causes significantly less drag than a service bay (at least when using 1.25m parts. Havent tested with 2.5m but I'd guess it's the same). 

Plus a bonus is that you can choos the size and fit as many fuel cell arrays (+other stuff yiu might need) in there.

[Teilnehmer]

Thanks! I didn’t even think about fairings.

[Eidahlil]

On 9/25/2015 at 9:15 AM, Teilnehmer said:

(No idea if it’s possible or not. I haven’t tried yet, but I’ll try.)

I'm already convinced this is possible, but I ran out of fuel slightly too early on the latest attempt. Maybe tomorrow.

Here's the craft file if someone wants to try adding more stages and finish this, or just use for inspiration: http://kerbalx.com/juzeris/Ionorbanor-4

(Take off from the high point @Teilnehmer indicated above, heading 90, pitch 6-7, after dropping the first stage, you might need to reduce that to 5. Once the ASL is about 18-18.5km and speed 300+m/s, pitch 0 to break out of the transonic region. You will be losing altitude for a brief moment, that's how it should be. After staging again, keep pitch about 2 degrees above velocity vector.)

Edited December 18, 2016 by Eidahlil
Flying instructions

[Teilnehmer]

Wow!

[Eidahlil]

As promised, here's a working version: http://kerbalx.com/juzeris/Ionorbanor-5

And a video of the test flight. Accelerated, obviously, the whole flight took about an hour of real time.

I had a weird teleportation bug once already in space (I blame Hyperedit), pretty sure it does not affect viability of the craft at all.

 

[Teilnehmer]

You rock!

 

BTW, you use engines stowed inside fairings. Do you think it’s possible to complete the challenge without this trick?

Edited December 20, 2016 by Teilnehmer

[Eidahlil]

1 hour ago, Teilnehmer said:

Do you think it’s possible to complete the challenge without this trick?

I'd say it probably is.

My earlier iterations did not use it, and they mostly worked for any of the parts of the trip, they just could not do it all at once. One could make a huge serially staged thing like it, if part count was not an issue, and get to orbit with it.

It might even be possible to do it without putting anything on the back of ion engines (which is the main abuse here), but you would end up with a very pancake-like design.

The core problem here is that fuel cells are mounted radially, and radially mounted things generate a lot of drag (generally). So it's nice to put them into a fairing. And then I could not find an elegant way to use the 1.25m body for ion engines - multiple engines end up mounted radially, a single engine is really insufficient. But then again, mounting a lot of the little nose cones on the sides and putting the engines behind them would probably work.

But I will not be the one to attempt that.

Edited December 20, 2016 by Eidahlil

[Teilnehmer]

Added a badge. See the first post.

Edited December 29, 2016 by Teilnehmer

[Teilnehmer]

Wow! Bradley Whistance got into Kerbin orbit with ion engines! I’ve never even considered this possible. The most exciting thing, however, is that the Kerbin orbit was not enough for Bradley!

 

Edited April 21, 2019 by Teilnehmer

[Xurkitree]

This ofcourse means he won this right? give him the badge.

[Aeroboi]

You could add stageable ION's each carrying the required batteries (EC) for the Xenon consumption and then stage off to the next stage where each stage carries enough batteries to consume the Xenon of each next stage. Also have each stage carry it's required wings as in the video above.
Batteries are very energy dense and you could couple it with some static solar panels to reduce the total required batteries on each stage.

All you have to do is manually unlock each xenon tank and battery of any subsequent stage, honestly, that is cumbersome, maybe there's a mod that can do this automatically because asparagus on ION seems not to be working. If it's possible (I'm not sure) perhaps the length of the challenge is to get a Kerbal away from Laythe as far as possible.

Edited April 24, 2019 by Aeroboi