Spaceplane off EVE!!??

[septemberWaves]

45 minutes ago, Joseph Kerman said:

Space Shuttle Atlantis

Space Shuttle Atlantis, like every other real spacecraft ever used in reality, did not break any of the laws of physics. I don't know why you're pointing it out, unless it's because it doesn't use airbreathing engines. In which case, perhaps I should've specified that I meant SSTO spaceplanes, but since that's almost always the context used whenever the word "spaceplane" is mentioned on these forums I didn't think it was necessary to be so specific.

[Arugela]

It does not need to be an SSTO. Just a space plane. And if you really want, very little space plane. The point is as much weight off eve as possible. I just think there could be more interesting ideas with heavier space plane emphasis to explore.

Technically you can do hybrid rocket and space plane if desired. Especially if it's more efficient.

Edited June 16, 2017 by Arugela

[septemberWaves]

4 minutes ago, Arugela said:

Like I said, it does not need to be an SSTO. Just a space plane effectively.

You have to use rocket engines at Eve, since airbreathing engines do not work. You are guaranteed to experience quite a lot of loss to drag because of Eve's thick atmosphere and the fact that it's impossible to create an infinitely thin rocket. A rocket-powered spaceplane would not save you any fuel, since the only rocket engines which work at Eve's sea level are the same ones used on rockets, and the added mass of wings would actually make your vehicle consume more fuel than a vertically-launched vehicle with comparable payload.

Still though, you seem fairly convinced that this will work. The rules of the Challenges subforum state that the person posting the challenge should attempt it, so I'd love to see your entry for this challenge since you appear so sure that it can be done.

Edited June 16, 2017 by eloquentJane

[Gaarst]

Spaceplanes are more efficient on Kerbin because they can use very-efficient jet engines with TWR below 1, which make up for the additional mass and drag of the wings and structure.

You can't use jet engines on Eve, and the increased drag require higher TWR. You're left with a spaceplane with none of the advantages but all of the flaws of the design. It's not going to be magically more efficient than a rocket with minimal dead-mass.

Theories can have some limitations, but the theory that says you can't have magical energy out of nowhere (a.k.a. maths) is pretty accurate. You are free to try it yourself but unless you use some sort of Kraken drive (which probably could be fitted on a rocket anyway), I can guarantee that you won't be able to get better performance than with a VTVL.

[Arugela]

Could you get enough lift to use LVN's to float up slowly? Even if you have to drop LVN's on the way. Or at minimum punching up to a higher altitude with a rocket if needed and use lift plus nukes to hypothetically get a higher payload than a pure rocket?

The point is simply to ultimately get higher payload off Eve. No matter how small the gain.

Edited June 16, 2017 by Arugela

[sevenperforce]

1 minute ago, Arugela said:

Could you get enough lift to use LVN's to float up slowly? Even if you have to drop LVN's on the way. Or at least starting at a higher altitude if needed and hypothetically get a higher payload than a pure rocket?

No, because LVNs have virtually no thrust at sea level on Eve. They are very pressure-dependent.

What you could do is use something like a helicopter to get high in the atmosphere and then fire up rockets. But, critically, you are never, ever going to be able to get any significant fraction of orbital velocity in air-assisted flight on Eve. It just doesn't work.

[Arugela]

I didn't say it had to be pure SSTO. You do not need to get off eves surface with nukes. You can use a rocket to push the levels the LVN is more useful. You can also drop the LVN's. But can you use lift to help make the LVN's get a better payload off. Even if it's only an extra ton or something? It might help it get back to kerbin as that seems to be an issue.

And yes the helicopter is an interesting idea. could you do that and get to the highest point of eves atmosphere and slowly build up velocity on the way up with the nukes? Can you use electricity for rotation? I haven't done helicopters yet. Not that electricity matters if you just drop it afterwords.

You are only at like 12.6 gravity at that point. So, either very small vehicle or very large parts count!! 8d A lift monster might allow it to stay afloat until reaching higher speeds and getting away from the atmosphere. you could always burst with another engine like vector or mammoth then drop it. Obviously a lift monster on Eve takes less wing space. That being one reason why I think it might be useful on eve in the correct application.

I was messing with only using the smallest parts in the game also. I would take the smallest tanks and drop them as you go for more efficiency. But the parts count got out of hand. Or else it might have worked well. Might be applicable. Maybe for a starting stage, but those are obviously less weight efficient per thrust if I remember. Is there nothing about lift that would help get a payload off easier?

BTW, terriers are a potentially good match to nukes. They have fairly good ISP and smaller weight and they add thrust vectoring. Obviously not as good thrust to weight overall as a mammoth but you get better combined ISP and can get a smaller version with the nukes at smaller plane weights. 1 LVN+4 terriers might be decent for short term burst abilities then drop the terriers and uneeded nukes. 1 LVN+4 Terriers can do 18 tons(after engine weight 23-5=18tns) of plane at 12.6 gravity per grouping. You might be able to use it as upper stage to extend range a bit. A trick with nukes is to get a higher apoapsis with lower gravity and then circularize at higher altitude. Although I don't know how hard that would be here.

Hypothetically if you can find a way to use wings in the atmosphere you can drop some or all of the wings after getting out of atmosphere. But you might have use for them or some of them for better landing on kerbin.

4 terriers and a nuke average 436 ISP until you drop the terriers. That gives a little more flight time or lower trajectory and possibly less fuel usage if used to it's fullest. Hence fast spaceplane.

Mammoth is a lower stage lifting engine. It is not optimal for upper atmosphere. And everyone uses it that way like it's a magic engine answer. There are reasons for upper stage higher ISP engines.

And, technically, even if the rocket is more efficient in one sense, it might be less cost efficient. So, you could always look at it from the standpoint of trying to maximize return value. Not sure of the specifics though.

Or maybe the extra weight is carrying more science containers with research for more science return. Potentially, even, at a better overall price.

Surely, there must be some angle where using lift is better than a pure rocket for Eve ascent and return..

You could also use a lower stage reusable mining spaceplane to land after getting the upper stage into proper altitude and re-mine and wait for the next plane. This could make a low cost overall system and possible more efficient than a rocket if the ISP potential is maximized. it would have to be a specialized plane obviously.

I'm also wondering if, with the better ISP, you can get a higher apoapsis easier with a space plane design possibly eaking out better overall return with nukes for payloads. But it might require very good flight paths. You will get higher velocity on apoapsis with relatively lower trajectory flights like a spaceplane. So it might help with getting a nuke ship off eve for a much more efficient return once you get high enough. The trick would be maximizing lower and upper stages or likewise to get the best speed and weight off the planet.

Edited June 16, 2017 by Arugela

[sevenperforce]

1 minute ago, Arugela said:

I didn't say it had to be pure SSTO. You do not need to get off eves surface with nukes. You can use a rocket to push the levels the LVN is more useful. You can also drop the LVN's. But can you use lift to help make the LVN's get a better payload off. Even if it's only an extra ton or something?

And yes the helicopter is an interesting idea. could you do that and get to the highest point of eves atmosphere and slowly build up velocity on the way up with the nukes? Can you use electricity for rotation? I haven't done helicopters yet.

You cannot "build up velocity on the way up" with nukes, or anything else, because drag is too high due to the thick atmosphere.

Your proposal won't work for much the same reason that balloon-assisted launch on Earth is a bad idea. With a balloon-assisted launch, you release your orbital vehicle at high altitude, where it can use more efficient engines, but it is still releasing at essentially zero velocity. In contrast, if you lift it to the exact same altitude with a rocket stage, it is already moving at a fair percentage of orbital velocity. The latter will almost always outperform the former.

On Eve, you can potentially take advantage of the thick atmosphere and a solar or nuclear-powered helicopter to get high enough to make a significant difference in engine efficiency. But it would be tough.

[septemberWaves]

Quick question Arugela: how many times have you actually been to Eve and back? You'll find there's a reason people often use very similar rocket designs.

[ARS]

@eloquentJane is right, how many times have you go to eve and returned? This post seems to be a challenge (because no one has attempted it successfully) but the rules of challenge in KSP stated that the challenger have to already performed it to prove that it can be done. I've been playing KSP for 3 years and I've been only on eve (and returned) 3 times. The first 2 uses a monstrous rockets that makes my laptop lags A LOT, while the last one uses a spaceplane with modded engine

Now this is what interesting: the last time I'm doing it with spaceplane is a long time ago in KSP 1.1 (just testing it) by using modded engine (.cfg tweaked to match kerbin jet engine efficiency), however, no matter how I tried, it's either:

-running out of fuel before leaving atmosphere, even if it's as efficient as jet engine on kerbin

-planes being destroyed by drag heating. I can avoid it by throttling down, but then it wastes A LOT of fuel

-insufficient fuel to circularize orbit, mainly because of throttling down trying to avoid burning up inside eve atmosphere mentioned above

-not enough fuel to return home, mainly because orbit circularization above

the main problem is, even if you have an engine efficiency comparable to jet engines on kerbin, eve's higher gravity, thick atmosphere and higher karman line increases the drag your plane experienced, so you stay longer inside atmosphere than a rocket that simply shoot straight up. You DO NOT want to stay longer in atmosphere when launching off eve, since you want to reduce the drag ASAP before it kills off your chance of leaving atmosphere and circularize orbit.

And no, using LV-N does not work, it's very pressure dependent, just like @sevenperforce said, you basically wasting fuel with no thrust at all if you fire it up inside eve atmosphere (it even cannot lift itself on kerbin). No offense, but you seemed to be highly optimistic that this will work, so I'll just wait for your entry to prove it (legitimately) and then you can boast off in the forum

Edited June 16, 2017 by ARS

[Laie]

@ARS: this is called "Challenges and Mission ideas".

2 hours ago, sevenperforce said:

Your proposal won't work for much the same reason that balloon-assisted launch on Earth is a bad idea.

Actually, that would be eminently helpful on Eve. Last time I tried, I still went up to 20km before even thinking about a turn, and didn't go very fast either. The atmo is thick, and punching through it fells more like scaling a wall rather than powered flight.

@Arguela: spaceplanes work so well on Kerbin because you don't need to carry any oxidizer; also, because KSP jets are totally overpowered relative to KSP rocket engines. Getting a jet/rocket combo to space requires a lot more dV than a straightforward rocket (wings are no magic lifting device, they also cause substantial drag). It works out because dV from jets is so easy to come by, the fuel savings pays for the wings and then some.

[ARS]

20 minutes ago, Laie said:

@ARS: this is called "Challenges and Mission ideas".

ah, my bad

[sevenperforce]

54 minutes ago, Laie said:

(me on balloon launch)

Actually, that would be eminently helpful on Eve. Last time I tried, I still went up to 20km before even thinking about a turn, and didn't go very fast either. The atmo is thick, and punching through it fells more like scaling a wall rather than powered flight.

Yes, balloon launch would work very well on Eve. Balloon habitats would work well, too...cloud cities, basically. On Venus as well. Not so much on Earth/Kerbin because atmospheric pressure is much lower.

I think an RTG-powered helicopter first stage would work well on Eve.

[Starman4308]

5 hours ago, Gaarst said:

Spaceplanes are more efficient on Kerbin because they can use very-efficient jet engines with TWR below 1, which make up for the additional mass and drag of the wings and structure.

You can't use jet engines on Eve, and the increased drag require higher TWR. You're left with a spaceplane with none of the advantages but all of the flaws of the design. It's not going to be magically more efficient than a rocket with minimal dead-mass.

Theories can have some limitations, but the theory that says you can't have magical energy out of nowhere (a.k.a. maths) is pretty accurate. You are free to try it yourself but unless you use some sort of Kraken drive (which probably could be fitted on a rocket anyway), I can guarantee that you won't be able to get better performance than with a VTVL.

To be fair, a rocket-powered spaceplane has one of the advantages of SSTO spaceplanes on Kerbin: you can get away with low TWRs because wings help eliminate gravity losses, generally at the cost of much higher drag losses (more time spent in atmo) and additional deadweight (wings). I don't think that balance comes out in favor of a HTHL rocket-powered craft, but I don't know of any theoretical way to absolutely disprove that you might not gain more advantage from having wings (allowing low TWR and reduced gravity losses) than not having them.

Also, there are concepts such as air-augmented rockets, where you can use inert atmosphere as a working fluid for jet propulsion. It's not as efficient as a regular turbojet/turbofan/ramjet, because you don't get free oxidizer from the air, but you can still get significantly better Isp than a pure rocket. Granted, none exist in stock KSP, or other possible technologies for using local atmosphere as working fluid, such as nuclear turbines.

16 minutes ago, sevenperforce said:

On Venus as well.

Well, at least after you ignore the incredible temperature/pressure near the surface, and the sulfuric acid hurricanes above cloud level. Those would make it difficult, just a bit.

[Arugela]

15 hours ago, sevenperforce said:

Yes, balloon launch would work very well on Eve. Balloon habitats would work well, too...cloud cities, basically. On Venus as well. Not so much on Earth/Kerbin because atmospheric pressure is much lower.

I think an RTG-powered helicopter first stage would work well on Eve.

Technically, in many version of KSP you could do cloud cities, but it's at about 500-1000m altitude... Not sure if you still can. But if you pile enough wings you can basically endlessly stay afloat. I think they, "fixed," it, but I don't think they completely fixed it! ;d

 

Not sure if you could accomplish one at 20k or somewhere useful for kerbin. Might be able to make a cool alt landing pad though. At least for Vtols. Maybe have it fly around and land(if possible) and mine or drop down a vehicle to mine on a tether if you use mods.

 

Could you do similar on Eve? I think a reusable first stage normal space plane would potentially be better though as it could land back on eve refuel and then wait to reconnect to a new craft to launch up to appropriate height for take off.(one time cost endless re-usability) might depend on mods or if you're using stock.

My normal SSTO's off kerbin are usually higher thrust but I don't know if they are high lift or medium lift. But lift endlessly helps with fuel because it forces the nose up higher so you make more out of your thrust. So that at minimum could be beneficial at some level to see if you can get a slightly lower trajectory plane off eve using higher ISP than a mammoth and possibly get a better likewise circularization for LVN's. This might help get less fuel if done well and make it more efficient and maybe help get a slightly better payload. Or that is something I'm wondering if isn't a possibility. It might need to be done perfectly to get any benefit though. Or do something crazier like helicopter or floating cities if possible. The steeper angled ascents are endlessly better on fuel relative to straight up ascents when it comes to actual circularizing at top(unless that is not beneficial in this case). If there is a happy medium or something this could make it easier to get payloads back to Kerbin if you can make it match the weight loss from a rocket. Maybe allow simply larger payloads. At minimum better than current space planes off Eve.

I think I always miss the obvious other thing. If you can get a small ship with some payload off Eve you can always go to gilly as a target instead of Kerbin. This allows refuels and possibly smaller end stage payload design as far as fuel goes. I do this a lot with designs for miners off kerbin. It is probably the most efficient for eve also. It gives some more design possibilities at the least. I just always forget about Gilly as a refuelling option. And unless there are issues finding ore to mine, Gilly is the ideal of ideal locations for refueling! So, you don't need to design for kerbin return. Just gilly refueling. Either with mining or an on location mining setup. Then you just have to do gilly to kerbin. And some the equipment to get to kerbin, if the delta V is greater(I forget) than Eve to gilly, can be docked on refueling and reusable to make up the difference and then reattached for a kerbin to gilly drop on the return. The other advantage of wings is it allows lower fuel return stages for getting back down to eve afterwords. And you could leave as much on gilly as possible and try to maximize weight. Of course is it better or cheaper than rocket dropping. I would imagine it's probably cheaper at least because planes are more reusable.

Mismatched node attachment sizes currently create lots of excess drag atm, correct? On top of massive drag from any uncapped node still?(forwards or backwards facing) AKA they have successfully forced universal use of connectors and caps on nodes at all location for efficiency under current game.

Edited June 17, 2017 by Arugela

[Skylon]

Now that we have finally decided that spaceplanes may not (and probably will not) be an efficient way to get off of Eve, why not Edit the original post and title and convert this into a 'payload to eve orbit' challenge?

Please also be much clearer with your stated values, I'm not entirely sure what you mean by 500k. 500km? If the 'cloud cities' are at 500km, then they are in orbit and their wings are not helping them. Also the thing about 12.6g something. I think you are referring to gravity, but what is the gravity at the surface? The gravity does not change much as you go up.

Honestly I'm not sure what you are trying to achieve here

Edited June 17, 2017 by Skylon

[Arugela]

Well, you could try either and post it. We would technically need a comparison regardless.

[septemberWaves]

A balloon-assisted launch might be interesting on Eve. Or maybe not balloon, but airship...

Actually, with an airborne runway like the ones you can create using the Heisenberg airship mod, I suspect an SSTO spaceplane might become plausible for Eve. I'm wondering if you could launch it from about 30km up with a large enough airship, reach orbit with better engine efficiency (because of the low pressure) and lower drag losses, and then aerobrake with the wings and glide to a landing on the same airship you launched from. This is probably the only good way of getting a spaceplane off of Eve (without the nuclear thermojets added by some mods) but it would definitely be more possible than an SSTO spaceplane from the surface.

I may try this at some point.

EDIT: for clarification, I meant a rocket-powered spaceplane, which should be obvious since jet engines don't work on Eve. The reason I'd use a winged SSTO instead of a rocket SSTO with this method is for precision landing on an airship.

Edited June 17, 2017 by eloquentJane

[Regor]

You know that Eve's atmosphere isn't oxygenated, right? RIGHT? RIGHT?!!

[Guest]

Stock props dont need any oxygen. 

[Joseph Kerman]

3 hours ago, dundun92 said:

Stock props dont need any oxygen. 

Right. Propellers actually work better with denser media than 1 atm.

[herbal space program]

 

On ‎6‎/‎17‎/‎2017 at 8:21 AM, dundun92 said:

Stock props dont need any oxygen. 

Stock props??

 

I like the helicopter idea! If you mounted some wings and a bunch of reaction wheels radially on the right tank/engine combo, you might just be able to pull off an Eve SSTO that way. Surely somebody has tried this already, No?

[sevenperforce]

5 minutes ago, herbal space program said:

I like the helicopter idea! If you mounted some wings and a bunch of reaction wheels radially on the right tank/engine combo, you might just be able to pull off an Eve SSTO that way. Surely somebody has tried this already, No?

I'll give it a shot. Bonus: you don't even need chutes, since you can autorotate down.

Dry mass would be a touch high--you'd need a bunch of RTGs inside a fixed fairing and a ton of reaction wheels. Alternately, you could skip the RTGs and use fuel cells.

[qzgy]

42 minutes ago, sevenperforce said:

Alternately, you could skip the RTGs and use fuel cells.

That might be an advantage, though then you also need to carry fuel. On the plus side, the mass goes down as you go up.

[herbal space program]

53 minutes ago, qzgy said:

That might be an advantage, though then you also need to carry fuel. On the plus side, the mass goes down as you go up.

Solar panels don't work? On Kerbin those provided plenty of power for a copter when I tried it before. I was able to pretty high up that way IIRC.