Planet types as gameplay limiters

I'm fairly certain Neutrino had commented on discussion regarding 'packaging' units to transport off planets for invasions. From this it may be safe to consider the possibility of building, for example, air units on a planet/object with no atmosphere, and then 'shipping' them off towards a planet with one.

Also, thoughts on having atmospheric density affect flight speed and height? Could just be a 2 tier system (atmosphere = no change, no atmosphere = 50% speed reduction). Lower speed would be easier to hit, thus discouraging air units on these planets without discarding them completely.

May be an interesting link between planet properties and gameplay.

Personally, I don't like the damage idea. It'd mean unit usability would last for only a short moment after it was built. I suppose that could just be part of the 'essence' of being on a lava planet, but to me just seems annoying.

I really don't like this as it doesn't make sense. Also for reference, in low density atmospheres, like say Mars, planes actually have to fly faster in order to stay up.

You could do two types of air units, some are aerodynamic based and require air. The others are like the space engies in the video and hover with rockets or some such and can work in air or space. This way space is different without being just annoying.

Ah, right I was thinking more along the lines of thrust, not how the plane actually flies.

Yes, I imagine two different flying types could work, a little like how TA had seaplanes that could land in water.

VTOL hybrid designs (using non-air-breathing engines) do lose significant speed when the air density increases their stall speed to above their maximum speed (or at least the maximum speed they can achieve in a short period of time). Being unable to transition from VTOL mode to cruising mode, they're constantly using 1g of their acceleration just staying in the air. (an aeroplane can get into the air without a thrust:weight ratio of better than 1, but a VTOL does not have that luxury).

However, atmospheric density also correlates with surface gravity, so while if you magically sucked all the air off Earth a hypothetical VTOL would lose performance, the decrease in surface gravity means 1g amounts to a smaller proportion of its total thrust, so while unable to enter cruising mode, its top speed in VTOL mode would increase considerably. Finding a good reason why you can't just build planes on an asteroid and have them merrily fly off into space and move to other planets will be difficult.

That correlation is false, Earth and Venus. and getting rid of air does not change the surface gravity, the mass of air on earth is not going to play into that at all. Non air based VTOL's should be better on a no air earth, no drag to fight.

By VTOL I meant things always in a vtol mode, the don't switch into an aero mode. Kinda like a rocket helicopter like thing. Efficient? no. Useful in more environments, yes.

To not fly off an asteroid you just turn down your thrust to match the local gravity which is determined by mass and size of the asteroid.

"A and B are correlated" is not the same as "A and B are proportional to each other". A single counterexample does not disprove a general principle. Furthermore, whether or not a given aircraft's performance will increase depends on its thrust:weight ratio. A fully loaded Harrier, for example, would obviously experience inferior performance on an airless Earth (assuming its engine were replaced by a non-air-breathing engine with otherwise identical characteristics), as fully loaded, the Harrier is incapable of vertical takeoff, and so would have no performance whatsoever.

A VTOL aircraft with no lifting surfaces that allow it to enter cruising mode is essentially the worst case of a VTOL which is capable of entering cruise mode. When there is no air, they have the same performance, while when there is air, the hybrid has a higher top speed, better range, and the ability to perform manoeuvres which the pure VTOL cannot perform. The pure VTOL may experience slightly better performance due to not needing to spend mass on lifting surfaces, but lifting surfaces commonly provide several other functions (support for armaments or other components, fuel storage, ablative armour) so this saving is minimal.

So what, now all planes are required by law to have thrust limiters installed when they leave the factory in order to not step on the toes of orbital units? There's a Space Police unit which pulls over planes and says "Do you know how many gees you were pulling then? Let's see your Space License."

I haven't read the rest of your argument, but this part is glaring false. By definition, a general principle must apply in every related situation. Maybe you mean something else, but you're not being clear.

Thrust to weight is not the only indicator of aircraft performance, Lift to Drag is another and there are a whole host of others out there.

My point about Earth and Venus was trying to say there is NO correlation. Titan is less massive and has a higher pressure atmosphere, mars is smaller, and lower pressure. Venus equal size but much higher pressure. surface gravity correlates with object mass and volume, and atmosphere has no significant contribution to either until you reach the point where you're a gas giant.

I'm not saying all planes HAVE to have thrust limiters, I was trying to solve the proposed problem of things flying off an asteroid.

The point I was trying to make was that a subset of 'air' units can be developed that work in any atmospheric environment, yes they will not perform as well as traditional ones, but they will function in a vacuum.

Lift to drag ratios aren't very well defined when both lift and drag are negligible because there's no air, so it's not a very useful comparison, is it? If your Thrust:Weight ratio is <1, nothing else matters when there's no air, since you can't take off at all (and something with a ration of ~1 will be virtually incapable of manoeuvring, making most other measures useless).

Well, looks like you're wrong about that.Here's a graph of all the gravitationally rounded bodies in the solar system's atmospheric pressures against surface gravity. I added a graph showing some data where there was actually no correlation, for comparison. The correlation may not be very strong, but it's detectible, and we're mainly suffering from a paucity of mid-range data points, due to the lack of decent sized rocky planets.

And your solution was almost as bad as the problem. The sensible solution would be to give planes limited reaction mass, giving them infinite range in atmosphere, but no ability to attempt orbital transfers, but this forum would go "STUPID FAT FUEL RESTRICTIONSES, WE HATES IT PRECIOUS".

And yet, any 'traditional' planes we see will also function in a vacuum just as well. Unless you want to restrict planes to taking off from runways or catapults, which will have the forum up in arms against you.

Yes your graph shows that there is some relation to surface gravity to pressure. BUT!!!!! it is a very limited correlation because so much has been simplified away, like content, solar pressure, radiation intensity, albedo, and I can go on. Just because surface gravity is high does not provide you a good indicator of atmospheric pressure, Earth and Venus are an example of where this is very not true, titan which is much smaller and lower gravity than earth has higher pressure. If I had time to do the research I could probably get a better correlation based on content of the atmosphere.

But it is a ONE way relation, unless you are a gas giant (a totally different scale) your atmosphere has very little impact on your surface gravity, in an earlier post you argued that removing earths atmosphere would reduce the surface gravity.

As you have said earlier traditional planes flight surfaces would be useless in a vacuum, a VTOL plane that is meant to cruise with wings should have almost no horizontal velocity and extremely limited flight time due to insufficient fuel reserves. They would not be as capable by your logic.

Rockets in the distant future do not have to be as inefficient as they are now with fuel. There are developments out there for electric propulsion and nuclear rockets that are in some cases, as mass efficient with their fuel at similar levels of thrust as open air technologies. And yes, people have considered hovering jets in real life, so at some point in 1000's of years, it is conceivable to be that we could see hovering rockets as a serious consideration. (I mean specific impulse when I say efficiency).

If you want hyper realistic aircraft, you WOULD use runways, VTOL is a significant performance hit to include, you generally get worse performance with less payload.

And here you've discovered that "correlation" also says nothing about possible better correlation with other variables, but you're still missing the point, which was that airless high-gravity worlds are rare.

I did not. Show me where I said that, because I think you'll have trouble finding a quote of me saying something I haven't said.

What the hell are you talking about? What's limiting the horizontal velocity of a winged VTOL, and what's limiting the fuel reserves of a winged VTOL that isn't limiting the fuel reserves and horizontal velocity of wingless VTOLs?

There's nothing that says a "hovering rocket" can't have wings. Take a look at the Hind. Pretty standard helicopter, right? No aerodynamic lift generated by wings there, you say. But nope, when in forward flight, about 25% of its lift is generated by its winglets, and the hind is a cow of a helicopter built in the 1970s by the Soviets. Even staying with the 'attack helicopter' body plan, a lifting body design would mean greater top speed when in forward flight. And while you're at it you might as well mount some control surfaces on those wings to supplement your vectored thrust. And suddenly you've made what's basically a fat VTOL aeroplane.

Unless I'm mistaken, I believe this was what they were referring to. I'm a little lost as to what you both are writing about though, so I may have misunderstood this completely.

Anyway, you're both arguing about realism. I believe there were multiple atmosphere-less planets in TA, yet that didn't stop aircraft from flying, and did not harm the game immersion.

Those are referring to two completely different situations. The first is saying that a plane would take a performance hit if you sucked all the air off the earth, the second is referring to the fact that said hit would not be present on naturally airless worlds due to their propensity to be lower gravity.

If this is ok, what is the problem with what I proposed?

And assuming something is rare because it does not exist in our solar system is a bad assumption because we have evidence of at least two types of planets (super earths 6* mass of the earth, hot jupiters) that don't exist in our solar system, there is a lot we can't tell about others right now. If the Earth was where mercury was and had no magnetic field, the sun would have blown the atmosphere away (On a cool note, we're seeing something like that happen to an exoplanet).

And I'm sorry I assumed that you were using correlation wrong in your earlier post. But please continue to use statistics to ignore far more important factors, because by only looking at one correlation you are missing other concerns with more impact, like the COMPOSITION of the atmosphere. Which is my point, there are STRONGER correlations, just because you can find a weak one does not mean much.

And sstagg1 got the post I meant, fine, I misunderstood a very poorly phrased sentence.

Lets get back on track people

Your proposal was splitting aircraft into VTOLs and "true" planes, when really the kind of tech you'd need to make aircraft viable on airless planets at all and the general lack of runways would basically erase the distinction between the two.

It wasn't a flat assumption based on our lack of evidence. Physics says that heavier planets can maintain a thicker atmosphere, due to lower loss rate from thermal motion, so even if we have no evidence of them, we can safely assume that heavier rocky planets will likely have thicker atmospheres, all other things being equal. As for lacking magnetic fields, I believe geological activity is also something that's correlated with mass (All the small rocky planets are geologically dead, presumably because the processes driving them (which aren't really fully understood) ran out many millions of years ago), so earth-sized planets will also tend to have earth-sized magnetospheres, and larger planets will have more powerful ones. And before you mention Io, that's an outlier due to its geological processes being driven by tidal forces from being super-close to a gas giant.

This is more relevant than you both realize...

I think the OP did a great job of indicating what is possible with planetary properties limiting gameplay options.

Also, as if to completely ignore my own point above, think of it this way:
- With no water, you can't build naval.
- With no land, you can't build land.
- It only follows that with no atmosphere, you can't build air.
- For orbital, perhaps there could be too much debris around the planet to keep anything in orbit long enough to be effective (thus preventing orbital from being built)

I'm not a fan of simply preventing a unit type from being built, but that's how it works with land and naval, so it might as well apply to everything.

In TA and SupCom, this didn't apply, but since we're dealing with multiple planets, it may be time to look at it a different way.

Actually it did. There was exactly one airless world in TA, Dump, and it was a no-fly zone, which made little sense due to the fact that every single plane was a VTOL.

oh yuck, I see this has devolved into a big ugly flame war over the realism of flying without air.

Seriously guys?

Yes, there were planes in TA.
Yes, they were VTOLS.
Yes, the Hind is a VTOL.
Yes, the A10 is a VTOL too.

But...

There is a big difference between a VTOL, and a self propelled craft that can operate in a completely airless environment. Comparing a plane to a hind is just wrong here. You need to compare the plane against a lunar lander. I'm not sure I'm even comfortable with the word flight when we take air away. It's a completely different process.

All the examples I see you people arguing over, are VTOLS. However they all depend on air to operate. They use rotors or wings to provide some or all of their lift. Without air, you crash.

It is possible to fly without air, but it is a completely different process. Once again, we're talking about a lunar lander here. You need thrust, and maneuvering jets. You have no air. It is possible yes, but very very different.

So really, I'm okay with airless moons as a justification for no planes.

I'm even more okay with extreme storms as a justification, since both types of craft have a really tough time with high winds, lightning, low visibility, these make it downright suicidal to fly anything. And keep in mind, we're talking planetary weather patterns. We're talking storms that cover the entire planet forever. These ain't your little storms from Kansas boys and girls, these are bigger.

What. The Warthog ain't taking off or landing vertically. Just look at it.

The lunar lander was made with 1960s tech and needed to be light enough to be launched on a 720,000km round trip and still support two meatbags. The margins involved were ridiculously tight because the USA's tech in 1969 probably wasn't good enough to really be attempting a moon landing, but they did it anyway. Forces in PA will have wireless power transfer, easy element transmutation and the ability to economically recover materials from virtually anything, including rocks and dirt, and use said materials to assemble tanks in seconds. Comparing a lunar lander to a PA aircraft is like comparing the Wright brothers' experimental flier to the F-22. With the tech in the hands of the PA forces, non-air-breathing versatile reaction engines are basically a solved problem (and that's assuming they don't go as far as SC* and have reactionless drives). The issue is not "should planes be able to operate without air", but "how can we restrict planes so they won't be able to logically operate in deep space?".

*Which was lower tech than TA in a lot of important ways, but higher tech in a couple of areas.