Jovian Scooping

[NeuralKernel]

I've been flying scoopships for quite a while, modded up my old Wave a while back to fit one but these days I like to just manually fly around in a bare-bones Mola Mola fitted for prospecting (atmo shield, shield, f scoop, c scoop, level 1 hyper and mining cannon) and just drift along.I can handle almost any planet out there, and with a quicker ship like a Pumpkinseed I can handle anything smaller than a Brown Dwarf (might try that, actually...) but I ran into a Problem with my Mola Mola while running Hercules.Everything worked fine until the hold filled up with hydrogen and the extra mass meant that even the main drive wasn't strong enough to hold altitude, never mind climb! I hit the "ground" but slowly enough for the shields to absorb the damage and then tried to jettison some of the cargo (too much mass to jump anywhere...) but as soon as the cargo left the scoop would just automatically grab it again... nothing I tried worked to ditch the stuff!I ended up just quitting... I could have tried burning off remass until I was light enough to climb, jettison and jump... but the Mola Mola is an efficient ship... :/Not sure what to suggest as fixes but here are the biggest problems. The atmospheres of Gas Giants are still too shallow by at least an order of magnitude. There are no aerodynamic forces on ships except for drag and heating. The issue of "fuel" has still not been addressed, refilling the "fuel tank" should use the "fuel scoop" and I still say the most logical way to handle that (in both the game and real life future) is by using hydrogen instead of water... but will keep a "cargo scoop and mining cannon" so I can refuel anyways until I figure out how to change it myself...I'll finish by saying that despite my bitching Scooping has been getting better and better! The recently added Vertical Speed readout has been a huge help for Orbital flight in general but Jovians in particular and the performance has noticeably improved lately even with high detail. Keep up the great work and I'll keep throwing myself down ENORMOUS gravity wells for fun and profit!!

[nozmajner]

I managed to scoop Hercules with a ship I'm working on. It was quite loaded up with equipment, so it was quite heavy. It had about 3.3G main acceleration, same as a fully loaded Mola, so it was quite a though job. I picked up about 190t of hydrogen. It was a long a trial and error and a lot of reloading but I managed to climb up and gain altitude very slowly. I had to balance vertical speed during the final 1-2000 thousand meters.I think it might possible with the Mola too, if you glide in a good angle and keep an eye out not to loose too much horizontal speed. I was at about 22km/s lowest when I finally made it. It was a pain climbing it back to 44km/s-ish for a stable orbit. The other thing I noticed is that you need to point the ship forward to start scooping, so jettisoning could work if you point the nose up, but I'm not sure. I agree with the too thin atmosphere, but it might be equally hard with thicker atmosphere since you will loose horizontal (orbital) speed either way so it could only mean a longer fall.

[lwho]

The only real problem with gas giant atmospheres seems to be, that it uses the gas parameters of air (gas molar mass and specific heat). In fact all planets use the same set parameters. I did some experimentation using a different set of parameters for gas giants (those of an average helium/hydrogen mixture). This gave a lot shallower density gradient which approximately matched the data I found about the gas giants in our solar system. I still have the patch around (not very big), and can make a pull request on the weekend if wanted. 

[fluffyfreak]

@lwho, that'd be interesting and probably a good patch to have.We really need a better way of rendering the gas giants too so that we can drop the physical "surface" much deeper and have a truly thick and deep atmosphere.

[NeuralKernel]

If anyone has given though to liquids that might be useful, too. I've heard talk of a way to land on water to refuel, maybe do some fishing over the side...If you can fiddle with the gas parameters would that make a big difference with Venus, too?

[fluffyfreak]

Landing on water right now would just mean allowing you to land at the zero height. There's no liquid simulation.

[lwho]

Sorry for the delay, but the pull request is now online: [url]https://github.com/pioneerspacesim/pioneer/pull/2609[/url] As for the Venus atmosphere: It is a carbon-dioxide atmosphere which is similar enough to air: 15% lower specific heat, 50% higher molar mass (hydrogen/helium compared to air has a specific heat 13 times as high and a molar mass of approx. 1/13th). The biggest difference is the much higher surface pressure of 92 atm. The game already handles different surface pressure just fine, so no need to use another set of parameters for venusian atmospheres.

[NeuralKernel]

It's been a while since I've been able to do much flying... but I just did a dry run with the starting ship in v20140201 into the Atmosphere of Uranus and the difference is amazing!!! I'll have to cheat myself up a proper rig for some experimentation but I was able to aerocapture quite easily from a bit more than 50kps without any real effort after a manual flight to Uranus from Earth... I'm going to see if I can use the new Jovian Atmospheres to Aerocapture from higher velocities, great way to get around quicker if you can save on deccelleration remass... Speaking of remass... when can we refuel with the fuel scoop?! Please just let us use hydrogen as remass, it's by far the most efficient propellant for deltaV and the in-game "Mining" process is far more reliable and mature than the cannon+cargo scoop combo...Some folk keep saying that there are plans to eventually add all sorts of neat options for gathering water for remass in all sorts of different ways but we've got a working Fuel Scoop system already developed and ready to go with just a single tweak.

[lwho]

it's by far the most efficient propellant for deltaV No, it's not. Mass is mass. If you throw the same mass with the same velocity out of your back window, it will give you the same thrust. And water is much safer to handle (try to fill the same mass of hydrogen into your water tank, and it might just explode). I'm wondering anyway where they put tons of hydrogen in these ships, that would either be huge, or under a immense pressure, or both.  The interesting question is, what does the ship use as a power supply for accelerating the water to the exhaust velocity? That's where hydrogen might come into play.

[NeuralKernel]

In real life and in-game Hydrogen is by far the most plentiful element. I can fill the hold with hydrogen in a matter of minutes "in the wild" by scooping a Jovian, even the largest ship will fill up fairly quickly. Those large ships also have engines that sometimes need thousands of tonnes of remass to replenish and it would take literally days of real time work to replenish my Reaction Drive by blasting and running down individual bits of water off asteroids.Jovian Scooping works... it works great in the latest versions with the new atmosphere modelling!! Its a practical way to grab a whole lot of Mass from the Game's Environment and it happens to be Hydrogen.For in-game purposes of trade in Hydrogen and it's use as fuel for both Reaction and Hyper Drives I would say that it should be handled in a Metallic State.[url]https://en.wikipedia.org/wiki/Metallic_hydrogen[/url] Hyperdrives, incredibly powerful but harmless Reaction Drives... why not safe and convenient Metallization of Hydrogen for compact storage?Mostly it's a gameplay thing, if you need to gather a few dozen (or a few hundred or a few thousand...) tonnes of Mass that you intend to throw away really fast to move... then scooping beats mining hands down.

[walterar]

You guys complicate things a lot. Now I'm going to visit my friends Mu Herculis, taking advantage of the new and very useful feature newly added lwho. :fan:And... I'm going to use High-Power-Ion Propulsion :gaming:

[fluffyfreak]

Speaking of remass... when can we refuel with the fuel scoop?! Please just let us use hydrogen as remass This is what I'd prefer, I know there are some arguments for keeping it as water but frankly, I think it make the gameplay suck if use different fuels for each thing so would be happy to see it switched back.

[lwho]

I think it make the gameplay suck if use different fuels for each thing so would be happy to see it switched back. Hmm, some details I'm wondering about: Should jumps take their fuel from the fuel tank instead of the cargo hold then instead?Should we be able to move hydrogen freely between tank and cargo hold (I think, currently only cargo -> tank is possible)Or should tank and cargo hold just be merged (what should the fuel meter show then)I'm going to bed now.

[fluffyfreak]

1. Leave as is, jump fuel from cargo hold.2. Maybe add it as an option - but having separate tanks is ok for me.3. No, these need to be kept separate for obvious reasons, you might jump into a system but have no fuel left, or plot a jump, take-off and discover that you don't have enough fuel by the time you reach orbit. The original system was the best, Hydrogen for thrust and jump. N-tonnes for Thrust in a "fuel-tank" and the cargo hold for jump fuel. The reasoning behind it might want some work, perhaps people would like a handwavium reason, doesn't matter to me I just think that the gameplay was better.

[NeuralKernel]

I've done a few more flights above a few different planets, my craziest so far was hitting the Atmosphere of Hercules at a bit more than 250 kps!!At what distance does the switch to flight relative to the Planet vs Star happen? As far as I can see from the Navigation Screen it looks like it sometimes happens when you get within the distance of the furthest satellite... it appears that when approaching Saturn vs Hercules that you switch to flight relative to Saturn much farther out from the planet, for example.On another note... now that I've skimmed Hercules... what's the word on Solar Scooping?

[Marcel]

Perhaps Solar Scooping could require instillation of a heliospheric shield. It could be a high-end version of the atmospheric shield and cost more. Maybe weigh more as well. edit: I'm in the one tank camp. You could make scooping water more interesting by having the player hover over the surface at near landing gear collision mesh height and assume that the thrusters vaporize the water and a magnetic fan-type thingie draws in the vapour and fills the hold. You’d go to a gas giant for the hydrogen, then stop by one of its moons for the water/ice. It's still rather tedious though.

[lwho]

At what distance does the switch to flight relative to the Planet vs Star happen?As far as I can see from the Navigation Screen it looks like it sometimes happens when you get within the distance of the furthest satellite... Yes, I think the non-rotating frame reaches out to the apoapsis (the furthest point) of the orbit of the furthest satellite. So, if this orbit is highly elliptic, it might be a lot farther than the current position of the satellite. That's just from memory, though. I didn't crosscheck in the code. The rotating frame of the planet is essentially when you enter the atmosphere (i.e. when the 0.00 atm pressure appears). So, even the thinnest upper atmosphere layer rotates with the same angular speed as the planet surface.

[NeuralKernel]

Just did a run at a Small Jovian with no moons and it didn't switch reference frames until I was about 50 000 km out... I can eyeball it to a certain point but you NEED instruments to do it properly and reliably and you need those instruments to be useful a lot sooner than they currently are...The atmospheres are deeper... time to make the Gravity Wells (reference frames?) deeper to match?

[lwho]

I fail to understand what you mean. Frames are a completely internal concept. Ideally, they wouldn't be noticeable at all to the player. And except for the switch from non-rotating to rotating frame they normally aren't. If you mean, when the altitude display appears, that is completely independent of frames (It used to be coupled with the rotating frame, but isn't anymore for some time). Currently, it appears at 10,000 km or 0.5 radii of the planet (whichever is lower).

[NeuralKernel]

Well I use the Navigation Screen as "Instruments" for Orbital Flight... F2 then F6 gets you the System Map with your trajectory plotted as a red line... but it's the trajectory according to the current Reference Frame so until the Frame switches to the Jovian world you don't get trajectory data about it. If the Reference Frame switched at a farther distance you'd be able to adjust your vector from farther out and at higher speeds to just skim the planet (or slingshot around it!)... right now I've got to eyeball that insertion.