Deddly

Ion Plane Research Challenge

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There was once a wonderful and entertaining challenge by @GoSlash27 that culminated in a successful SSTO spaceplane powered by nothing other than ion engines and electric charge. Even with what were back then massless parts, it was an incredible accomplishment.

Today, a lot has changed. Because engines work more realistically in atmosphere nowadays, the ion engine produces hardly any thrust at all at sea level on Kerbin. I have seen a few speculations that an ion plane might be possible, but I've never seen one work. So here's the challenge:

 

TAKEOFF CHALLENGE: Can you get a plane to take off from the runway using no propulsion other than ion engines?

 

Alternatively:

UP, UP AND AWAY: Can you invent an innovative launch method to get an ion plane in the air and beyond?  (Rover wheels to build up speed on the ground, take off from a mountain, electric propellors etc., but not a rocket booster stage)

  1. @Ultimate Steve refined his plane - now Ion Plane 7B - and managed to climb to 7537m from the top of a mountain.
  2. @Ultimate Steve launched from Kerbin's tallest mountain and could actually gain altitude and speed from there. Top speed was 70.4 m/s

Also valuable for research:

FREESTYLE: What is the lowest-altitude stable and level flight you can achieve using only ion thrust? (Anything goes to get your plane up there to start with, but the plane must be able to hold itself at that altitude and speed under its own power)

  1. @Draconiator can fly his plane at just 3480m altitude.
  2. @wibou7 Used a SRB on a cart to boost Winter Goose to a high enough altitude that it could sustain flight. The craft can hold level flight at about 4250m @ 50 m/s

 

Rules: No parts mods or mods that change the gameplay, like FAR. Visual mods are fine, I can't see a problem with MechJeb and things like that. No cheating or hyperedit blahblahblah

I have attempted to take off using a cluster of ion engines and two enormous wings. Maximum speed on the runway was 8 m/s, and not even close to takeoff. Please post your failures also, so we can learn from each others' mistakes.

Edited by Deddly

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i tried this a while ago from the runway, no luck. ill try up up and away, probably only into the air, and I'm assuming that beyond is space?

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This having piqued my interest/curiosity, I spent a little while this evening trying to get airborne. Sadly I think that pure ion gliders are a thing of the past. I simply couldn't get my speed over about 9.6 m/s, and the (serious attempt) minimum I can remember ever having gotten airborne on is about 16 m/s (and that was in a very, very lifty craft). Adding more engines is impractical because of the need for extra solar power, which exponentially increases drag and suppresses speed gains. I even briefly tried substituting solar for fuel cells, but that didn't show much promise either - too heavy.

My energy for this endeavour is now sapped, but I would love to see someone pull it off. Green energy and green people just belong together! :rolleyes:
 

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9 hours ago, Srgtjyn said:

ill try up up and away, probably only into the air, and I'm assuming that beyond is space?

Well, Up Up and Away is a challenge to get the highest altitude you can, but I don't want to limit it to within the atmosphere if some genius comes in here and suddenly gets a Solar escape velocity :wink:

3 hours ago, The_Rocketeer said:

I simply couldn't get my speed over about 9.6 m/s, and the (serious attempt) minimum I can remember ever having gotten airborne on is about 16 m/s

This is very valuable information, Rocketeer. How many engines did you use to get to 9.6 m/s, and do you have a picture of the craft you got airborne at 16 m/s?

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I'm trying to get this to work, but I can only get up to about 6 m/s. The only other thing I can post right now is my Kerbaled ion plane made in 0.90:

Spoiler

RcjdsoD.png

It flew to the island runway, at an average speed of about 40 m/s. I will attempt to recreate this.

 

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Welp, I've gotten 13.8m/s running, after stealing  8.4 from the ramp down from the runway, and maxed around 30 going down the beach.  A test with a couple of junos indicates the airframe with its 9 ions isn't too interested in taking to the air until 46m/s or so.  Perhaps I need to think smaller, and perhaps the basic fin is lying about its rather nice lifting area to mass ratio.

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8 hours ago, Deddly said:

This is very valuable information, Rocketeer. How many engines did you use to get to 9.6 m/s, and do you have a picture of the craft you got airborne at 16 m/s?

Let me first say that I was casting a broad net with several different platforms and looking for a result that would be worth refining. Best speed was with 3/4 engines sharing a single fuel tank. Past experience tells me that the best wings are the Wing Strakes (although that could be very dated information now - @GoSlash27 might know).

The 16 m/s craft was not at all recent either. It was basically a stack of wings held together with (what were then) massless parts and pushed by a Twitch motor on 5% thrust.

I've been away from KSP so long and haven't followed the changelogs closely enough to be much use - many of the tricks we found before probably don't work anymore. That said, no amount of experience with older versions will beat thorough experimentation with the current release. Broadly speaking, the engineering principle is the same - minimise drag and weight, maximise lift and thrust. It wouldn't surprise me if pure-ion was mathematically impossible.

One avenue I thought of but didn't really test was binning the wings themselves and using angled solar panels to generate lift.

EDIT: Having scanned over the Ion Collier Trophy Challenge thread, I see that my Shrike III actually had a take-off speed of only 13/14 m/s. Of course that was before many changes in drag/massless parts etc.

Edited by The_Rocketeer

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Yeah, the strakes were the ultimate lift/drag component back then, but that is no longer the case. Aero now treats all wings as equal from a lift/drag standpoint. You would now be looking for the best area/mass.

 I haven't played with ion gliders since then, and all the data we generated is now moot.

Best,
-Slashy

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1 hour ago, GoSlash27 said:

Yeah, the strakes were the ultimate lift/drag component back then, but that is no longer the case. Aero now treats all wings as equal from a lift/drag standpoint. You would now be looking for the best area/mass.

That's true, though - as @Archgeek mentioned - the basic fin seems to have better stats than any other lifting surface.

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Hmmmm, I wanna try this,,,,here's my 0.90 ion plane for reference, as to what we could do back then. 

I'll be back :)

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First attempt was a HUGE failure.  I'm just aiming for a short uop right now.
  Long thin wings and lots of ion engines do not work.

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Just now, Draconiator said:

First attempt was a HUGE failure.  I'm just aiming for a short uop right now.
  Long thin wings and lots of ion engines do not work.

No failures here, just research :)
So how many engines is "lots", and what speed did you get up to?

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8 minutes ago, SpaceplaneAddict said:

Rover wheels and enough wings should push the thing into the air, and ion spam sould be good as well.

If you can do it, I do believe you'll be the first! Please give it a go and report back, I'd love to hear how it goes for you.

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17 hours ago, Deddly said:

No failures here, just research :)
So how many engines is "lots", and what speed did you get up to?

I got up to 10m/s before I ran out of batteries, and at least 20+

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I can see dropping an ion-powered space plane from a mothership not powered by ion engines. Any thoughts?

- Mr_Kerbal

:confused:

Edited by Mr_Kerbal

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And this one won't work either.  Testing with solar propellers give it a takeoff speed of 15m/s though...

 

6b74e48a266eb5934866c1ecc88c7064.png

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6 hours ago, Mr_Kerbal said:

I can see dropping an ion-powered space plane from a mothership not powered by ion engines. Any thoughts?

Certainly fits the Freestyle category

Edited by Deddly

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After realizing I was quite wrong about power generation being a lost cause here (It needs to last at least as long as your xenon does), I've seen fit to break the challenge down into two main sections:

  1. Come up with an airframe that gets a very low take-off speed while carrying a bunch of batteries and some power generation.
  2. Tweak that general design to get enough thrust from ions to maintain if not hit that take-off-speed.

To the end of step one, I've been experimenting with multiple hulls and extreme usage of that 12:1 lift/mass ratio the basic fin pulls off:

Mk3.png

This thing will take off at just under 25m/s as tested with a single juno, but a trio of ions could hardly even push the thing past 6.  The airframe also likes to dance and spin out as it approaches take-off speed, so I sense I need to think smaller.

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Brilliant work. Ok so we have a benchmark of 25 m/s as a viable takeoff speed. We might need to get that lower, but we are getting closer.

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And here are the results of thinking smaller:

screenshot31.png

This thing can just about hop into the air at ~13m/s, but only briefly.

screenshot32.png

It needs about 18 m/s to sustain take-off.  Still not as slow as I'd like.

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@ArchgeekThat's very impresive! it is still Juno powered at the moment, right? If can get the same performance from Ions, you become the first person to design an Ion plane that can actually leave the runway, however briefly!

@JetskiWhoah - do the ion engines not interfere with each other's thrust when stacked in line like that?

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