Tsevion

Here's another pure stock entry... I bring a full capsule for a time of 2:02:

I've got a door that meets your requirements on my cargo plane here... Requires no fuel and no power, it's opened and closed by landing legs. It does need gravity to work, so it would need some re-engineering to work in orbit, but on Laythe and Kerbin it would be fine. Go to 3:45 to see it in action. Craft File Here

Well, here's my latest entry... didn't improve too much, but here it is: The How Ionic VII Top Speed and top altitude were two different runs but they are: Top Speed: 1123 m/s Top Altitude: 30628 m And in this version I use no batteries... so 10% bonus Craft File I think this is my last attempt for the time being... gotta get back to making videos and 0.24 coming out and such.

Alrighty, I've actually beaten this, essentially by just adding some more wings and tanks to this craft, my current record is: 1022 m/s at 29319m, gonna see if I can do even better before a full post. Here's a craft file of my current best though, if anyone wants to play around and add more to it: How Ionic VI

Bit of a breakthrough, I've made a craft with no control surfaces, that with infinite fuel can make orbit... the secret is moar wing: I ended using two swept wings and a delta wing per engine, two engines a single xenon tank between them and a small probe core. Ground TWR maxes out around 0.4, but she's flies to the heavens. Seeing if I can use this knowledge to get higher legitimately. Craft File

Infinite fuel is in the stock debug menu, alt+f12 to bring it up, it's just a checkbox. as for wing to engine, I'm not sure... I've been playing around and it seems a high ratio is better... something around or more than 2 swept wings per ion engine seems ideal... I need to do some further experiments with even more wings, but around that point the actual weight of the wings starts creeping up, lowering TWR too low.

Well, I've played around, can't quite beat you, but here's a similar entry. Zero control surfaces. Maximum speed: 830 m/s Maximum altitude: 25656m

Really not sure, although I'd be very curious... might be worth starting its own challenge for that. My own attempts to figure an absolute theoretical maximum by running unlimited fuel end up pretty similar to that though, running around a 0.5 TWR, and it's really finicky at that speed and altitude, you end up gaining altitude and losing speed, then losing speed and gaining altitude, and your orientation has a lot less effect than you'd hope. When running pure wing you seem to need a TWR of around 0.6-0.7 to be able to make orbit, and building an ion craft with that high a TWR and still having lift is really hard... and having the delta-V to make orbit is, I suspect, out of reach for an SSTO... it might be feasible using a lot of ion engines, a pair of wings, and a lot of drop tanks / booster stages. When running using locked control surfaces as wings, on the other hand, you can make orbit with a TWR of less than 0.3. Some of my tests seem to be showing that if you use a lot of locked control surfaces as wings, you can reach orbit with pretty much any non-zero amount of thrust.

On paper the swept wings (best of the static wings) are pretty good, 1.6 lift for 0.05t mass, for a ratio of 32... and small control surface is 0.5 lift for 0.01t for a ratio of 50.... and both have the same drag rating of 0.02, so they shouldn't be that different. But the small control surfaces, being control surfaces, have an effective parasitic drag of 0... or possibly even negative. I made a craft last night with purely disabled control surfaces that is effectively anti-gravity... cruising at a leisurely 2 m/s and losing no altitude or speed... at all... it's like zeppelin. Interestingly it properly loses speed when climbing, but in level flight it effectively has 0 drag.

Can I be using rockets to speed him up? Because if so I've got 303 m/s here (first 15 seconds of the video):

Sad... but it matches with previous challenges to get to orbit with ion gliders... it's doable, but they need to use some drop-tanks at the very least, and most of the more effective designs used multiple stages. Not to mention infiniglide concerns, as I've yet to see any ion-glider, staged or otherwise that can get to orbit without having some control surfaces (frequently as the lifting wings).

The problem is, as you're seeing, having it lift any significant payload is extremely difficult... and it definitely needs to carry some sort of rocket to get it to orbit. Also all the wing surface will also likely cause drag in the middle phases, making the rocket even worse. I think there is serious potential to use a helicopter as a base to launch a smaller rocket from a higher altitude on Eve... but I think it's tragically inadequate for an SSTO.

From trying to get my electric helicopter working on Eve I learned some things... despite Eve's atmosphere making lift much easier to generate helicopters are a fair bit harder. Gravity fights you harder, and the thick atmosphere makes spinning up the rotors much harder. I think you may actually want larger rotors, so you can spin them slower so you lose less to atmospheric friction.

The trick is, with torque powered helicopters or flapping, the gains are strictly limited to the energy expended, placing hard limits on their capabilities... they are really only functional at extremely low speeds. Infinigliders are NOT the same... they exploit the math of control surfaces so they generate thrust proportional to current speed, essentially generating energy. It is NOT the flapping action that makes infinigliders function... that's just one of the easier ways to see it... I can design infinigliders that function with you just holding the control stick in a single direction.

I actually was trying one of these last night, as I've got a fair amount of helicopter experience... it was not going well. While you can build one relatively easily, they seem to top out around 20km at best, and that's with little to no load, and the helicopter weighs a fair amount. Trying to carry enough rocket fuel to boost the helicopter further just cuts down efficiency. It could be a neat strategy for an Eve launch vehicle, but not useful for an SSTO.

Yeah... I kinda just realized that...

Ah... I've realized the primary problem, we're talking past each other a bit... totally my fault. You responded to my numbers which was a test I conducted on Eve. Going back and checking, I was unclear on that. Since those are what you responded to, I assumed you were on Eve as well. Rereading your earlier posts, and looking at the picture again (to see the big BLUE planet that is totally not Purple) I realize you're still doing the Kerbin testing. You numbers suddenly make much more sense, and no longer require anything bizarre to explain them. I still worry about infiniglide polluting results when using flaps as wings... but it's significantly less of a concern to me knowing this, it's likely mostly just providing some bonus lift/speed during the early phases of the launch but at 40k on Kerbin the effects should be negligable. When I used my craft on Kerbin (Still infinite fuel cheating), it achieved orbit easily... so I'm hopeful for you to get a positive result on Kerbin. My numbers unfortunately still stand for Eve though... it's just not possible to get a pure ion-craft to orbit there.

The problem is, with the weight of that craft, 3 of those control surfaces will give considerable infiniglide power... it's near unavoidable, even (and I don't know why this is true, but it measurably IS) if you disable control on them. I'm definitely not saying you're trying to use infiniglide... you're probably trying quite hard to avoid it, but I've only found 1 way to not be leveraging infiniglide, and that is to not have control surfaces on your craft. Just one thing to check, take your craft near the ground and nose up until you're pure vertical... I bet you'll see your craft magically hover, even if you cut the engine... or at the very least fall very very slowly, in a magic anti-stall. Another thing you could try is use B9, or procedural wings, or modify the configs on some of the base wings to be the same size/lift as the flaps you're using as wings, and then try your craft and see if the results are the same. And I should add, I honestly hate to be telling you these things... as I feel like I'm kicking a puppy and robbing you of earned accomplishment. I just ran into this a TON myself when working on stock electric helicopters and ornithopters. I thought I had some great designs until I realized they were deriving more power from infiniglide than my intended propulsion... and literally the only stock solution I've found is to not use control surfaces... hence both my final helicopter and ornithopter rocking tons of SAS but nary a control surface between them. A side corollary, give me a plane with a glide slope of 10:1 or better and control surfaces on it, and I'll show you me flying it from KSC to the island with no power after takeoff... and if it has a minimum takeoff speed of 50 m/s or less, or a fairly large number of control surfaces, I'll do it without ever turning the engine on.

I'm pretty sure there's infiniglide going on there... or something else hinky... otherwise it doesn't make a ton of sense. The TWR of this I'm guessing is pretty close to optimal, but optimal is still under 0.5... meaning your maximum speed should be about 1/2 terminal velocity... and terminal velocity at that height on Eve is about 1000 m/s. Edit: Ignore that, I'm an idiot who can carefully calculate the maximum speed based on altitude and potential TWR, and totally miss the fact that I'm looking at the wrong planet.

The thing you seem to be missing is the problem constraints. We're not saying getting off Eve is impossible, we're not even saying an SSTO is impossible. What we're trying to determine is whether an SSTO made with stock parts can get off of Eve with no funny business/cheating. If we don't need it to be single staged (or we somehow try to use some linguistic trick to have stages anyhow) then it's easy (any standard Eve lifter works). If we ditch the stock parts requirement we can again do it fairly easily, using any number of mods (Hooligan labs balloons, firespitter electric props, the Orion Nuclear Pulse rocket, any number of options from Interstellar). If we ditch the funny business/cheating rules you can hack gravity, use infinite fuel, change some part configs, use an infiniglider, use a Kraken drive, or any number of other methods. The trick is within the system of constraints we've imposed the problem set becomes effectively finite meaning we can systematically analyze it and actually declare impossibility. The thing is, since among the rules there is essentially a "no funny business" clause, normal creative weasling that can make almost anything possible is not allowed. Our whole discussion here is based on this premise, and our effort is to explore the problem space and systematically eliminate possibilities. We can, with mathematical and logical certainty say a pure chemical rocket is impossible, the math has been done. Just as I can unequivocally state that you cannot add two positive rational numbers and get a negative number. We're now exploring other possibilities, but trying to say "nothing is impossible" is not only not useful, it effectively is working counter to our goal to narrow the problem space.

I admit to being extremely curious as to your design, and what your TWR is...

I played around with a pure ion glider last night, and a pure ion glider definitely can't do it. I made a minimal ion glider (smallest probe, single ion, single xenon tank (empty), and a pair of Delta-Deluxe Winglets), and turned on infinite fuel. It topped out at 51km doing around 840 m/s, it also took like an hour to get up to that... which is a lot more than a single xenon tank worth of delta-V. And even that craft is technically abusing infiniglide slightly. The only possible non-cheating method left that I can't eliminate completely is a hybrid ion glider / chemical rocket... but I think it's quite unlikely you can actually lift anything with an ion glider that could then give the boost needed to allow the ions to achieve orbit. Edit: For clarity, this was on Eve, not Kerbin.

Ayup, just 4. Probably do-able with 2, but 4 makes it easier. As long as you keep lowering the throttle you can get quite high... I think I finally stopped thrusting at around 50km. I screen-shotted the final orbit from the jet, you can see it, and can see I haven't used any Xenon yet. Oh, I should probably include the Craft File

I haven't tried this yet, but I know you can scale parts by editing the game files. Conceivably you could edit something like the trusses to be 5-10 km long... use Lazor to keep them loaded then just use a few to surround Gilly.

One of the biggest problems with ion gliders is actually removing the infiniglide issue. Almost every ion glider I've seen is actually leveraging infiniglide to some degree (I'm NOT saying this is intended by the craft designers, or likely even noticed)... on craft that weigh as little as the typical ion glider ANY control surface is going to have a non-negligible impact on performance. Frustratingly the only ways I've found to avoid infiniglide polluting my results is to either have no control surfaces (which makes flying rather tricky), or to use FAR... which is definitely not stock anymore.