So planetary landings all well and good, how the hell are we going to do planetary takeoffs?

[nexxo]

I'm curious as to how FD are going to implement this?

Since 450m/s is nowhere near enough to acquire escape orbit on earth (roughly 11.2km/s needed). Even @2.4km/s is needed to escape the moons gravity.

These speeds fall squarely between the minimum SC speed, 30km/s and top speed in 'normal' flight 450ish m/s. And of course we would be mass locked on the surface anyway....

So ideas anyone???

I'm sure FD have already thought of this, i'm just curious as to what its going to entail.....

You realise that you're thinking of the ship as a conventional rocket. It could just fly upwards (at 450 m/s it would leave the atmosphere in about two minutes) and then kick in the FSD, which wraps the ship in its own space-time bubble, separate from the planet's gravity well.

Handwavium, my dear boy! It's all done with handwavium!

 

[Defacto]

1,000,000 from the surface? Going 450m/s? That's a 37 min trip just straight up and down, and if you want to go 1000km to to the left or right, that's another 15 minutes. Circumnavigating a earth size planet in normal space in a Cobra??? That might take longer than a trip to Sgr A*.

If they're going to impose normal space speed limits on planets, then they'll have to give us some mechanic for picking a spot on the surface to land on from orbit. I'd be Ok with that actually. Having to fly back into space to get to the other side a little faster.

Oh, no, I'm just thinking of where the frame of reference will switch from the star to the planet's surface.

 

[Space Fan]

You realise that you're thinking of the ship as a conventional rocket. It could just fly upwards (at 450 m/s it would leave the atmosphere in about two minutes) and then kick in the FSD, which wraps the ship in its own space-time bubble, separate from the planet's gravity well.

Handwavium, my dear boy! It's all done with handwavium!

Agreed, given that energy is clearly *not* a constraint in Elite vessels (why would it be, in 1300 years time!) Straight up and out wouldn't break any immersion at all.

But 100km is def the right sort of altitude to switch to outer space for an Earth-like - as the poster suggests.

 

[Bruce Warren]

Be cool if we could moonlight as planetary airlines. Want to get from London to Sydney in a hurry? 60 miles straight up, short FSD trip to the other side and 60 miles down.

Put your seat belts on in the back we're about to put the hammer down

 

[Space Fan]

Be cool if we could moonlight as planetary airlines. Want to get from London to Sydney in a hurry? 60 miles straight up, short FSD trip to the other side and 60 miles down.

Put your seat belts on in the back we're about to put the hammer down

+1

Weren't us (over-ambitious) Brits, (as ever ) thinking of something like this - HOTOL program? - air breathing low Earth rocket? A sort of super-Concorde.

 

[fruitbat]

Of course at some point, your speed needs to change to being relative to the planet you want to land on, when would be the time to do that, and I wonder how TAS/IAS will be dealt with, if at all when flying in the upper atmosphere. And that would be different for every planet relative to atmospheric density and the radius of the planet in question.

 

[Space Fan]

Of course at some point, your speed needs to change to being relative to the planet you want to land on, when would be the time to do that, and I wonder how TAS/IAS will be dealt with, if at all when flying in the upper atmosphere. And that would be different for every planet relative to atmospheric density and the radius of the planet in question.

TAS - Nav beacon - maybe *that's* what they're there for!

IAS - I'm sure they would have the technology to calculate that from TAS and atmospheric / motion / airframe force sensors.

 

[Quineloe]

only wings of two can leave orbit

 

[Schmack]

It's obviously going to be a drop safe location and cut scene just like stations, res sites and anything else you have to drop from SC to achieve. I don't see it being 1000km above the surface. I see it being 9.5km from the surface, and when you enter the base you land and you cannot fly around the planet as it's not really there. Try flying to another star in SC instead of HC. It's not there. I could see them loading the instance with land like a res site and nothing interesting (like a res site) outside of the base area. Viola, you have planetary landings.

 

[777Driver]

Of course at some point, your speed needs to change to being relative to the planet you want to land on, when would be the time to do that, and I wonder how TAS/IAS will be dealt with, if at all when flying in the upper atmosphere. And that would be different for every planet relative to atmospheric density and the radius of the planet in question.

I have a feeling they won't bother with TAS, it will just be IAS - I know students doing PPL's that really struggle with TAS/IAS conversion lol. As you mention, it will be a nightmare calibrating for every different planet. Even setting standard barometric settings would be a headache. I think in 3300 we'll have a magic computer auto calculating.

 

[777Driver]

It's obviously going to be a drop safe location and cut scene just like stations, res sites and anything else you have to drop from SC to achieve. I don't see it being 1000km above the surface. I see it being 9.5km from the surface, and when you enter the base you land and you cannot fly around the planet as it's not really there. Try flying to another star in SC instead of HC. It's not there. I could see them loading the instance with land like a res site and nothing interesting (like a res site) outside of the base area. Viola, you have planetary landings.

nope - devs have already stated that all of the planet will be accessible. Considering every other developer is doing the same, it would be pretty stupid for FD to limit access on a planet to a small area. Besides the bulk of planets in ED will have no bases on the surface, they will just be for mining or exploring.

Also you can drop out much further from stations if you deselect them, I've also found that you can fly in normal space between stations, no popping in when you get close.

 

[PotatoOverdose]

I'm curious as to how FD are going to implement this?

Since 450m/s is nowhere near enough to acquire escape orbit on earth (roughly 11.2km/s needed). Even @2.4km/s is needed to escape the moons gravity.

These speeds fall squarely between the minimum SC speed, 30km/s and top speed in 'normal' flight 450ish m/s. And of course we would be mass locked on the surface anyway....

So ideas anyone???

I'm sure FD have already thought of this, i'm just curious as to what its going to entail.....

I think you're confusing some core units/physics.

If you go up at a constant speed of 450 m/s, you would "escape" earth's gravity well (not strictly true- in theory a gravity well goes on to infinity in some negligible manner but w/e) in a matter of minutes. It takes 11.2km/s of delta-V to get into orbit, but delta-v is a measure of impulse - not velocity.

Essentially, since gravity forces you down, you need to keep accelerating - acceleration provided by impulse. So, if you're going up at a constant 450 m/s in earths gravity well, you'd also be expending 9.8m/s of delta-v per second in order to maintain that constant speed. All spaceships in elite have near-inifinite* delta v, but finite velocity which is unrealistic (especially the finite velocity part), but there it is.

*actually the delta v is finite, limited by your fuel, but try running out fuel in this game in "normal" space - takes forever.

 

[Phosphora]

When you land on the surface you'll enter a cloned version of "Kerbal Space Program". You'll have to build a rocket from scratch to carry your spaceship back into orbit.

Cheers, Phos.

 

[Apos]

When you land on the surface you'll enter a cloned version of "Kerbal Space Program". You'll have to build a rocket from scratch to carry your spaceship back into orbit.

Cheers, Phos.

*insert elitist gloating towards mechjeb noobs here*

 

[Space Fan]

I think you're confusing some core units/physics.

If you go up at a constant speed of 450 m/s, you would "escape" earth's gravity well (not strictly true- in theory a gravity well goes on to infinity in some negligible manner but w/e) in a matter of minutes. It takes 11.2km/s of delta-V to get into orbit, but delta-v is a measure of impulse - not velocity.

Essentially, since gravity forces you down, you need to keep accelerating - acceleration provided by impulse. So, if you're going up at a constant 450 m/s in earths gravity well, you'd also be expending 9.8m/s of delta-v per second in order to maintain that constant speed. All spaceships in elite have near-inifinite* delta v, but finite velocity which is unrealistic (especially the finite velocity part), but there it is.

*actually the delta v is finite, limited by your fuel, but try running out fuel in this game in "normal" space - takes forever.

I wish folks would stop going on about escape velocity and delta-V etc. It is simply not relevant. It is totally erroneous.

I've posted this politely 3 times. I've been teaching it to physics students for 20 years - and not got it wrong so far. Impulse is measured in Newton-seconds, or in kg m/s - it is *not* a velocity. But that's not even relevant in this discussion.

You just need to provide sufficient thrust to overcome gravity and gain some acceleration. Once your thrust is sufficient to equal your weight and atmospheric drag, you can then can pootle out as slowly as you want. You could stop and hover if you really wanted.

No more escape velocity or delta-V - *please?* The entire thread title is based on an incorrect assumption.

If anyone would like to sticky me, I will provide a full explanation.

Thanks

 

[Defacto]

I wish folks would stop going on about escape velocity and delta-V etc. It is simply not relevant. It is totally erroneous.

I've posted this politely 3 times. I've been teaching it to physics students for 20 years - and not got it wrong so far. Impulse is measured in Newton-seconds, or in kg m/s - it is *not* a velocity. But that's not even relevant in this discussion.

You just need to provide sufficient thrust to overcome gravity and gain some acceleration. Once your thrust is sufficient to equal your weight and atmospheric drag, you can then can pootle out as slowly as you want. You could stop and hover if you really wanted.

No more escape velocity or delta-V - *please?* The entire thread title is based on an incorrect assumption.

If anyone would like to sticky me, I will provide a full explanation.

Thanks

Well you could pootle along slowly, but in any circumstance, you will find that your total Delta-V (also counting losses) equals at least the escape velocity when you have escaped the well of the planet.
I don't think PotatoOverdose is wrong as much as you are just misunderstanding each other.

Also, on the Delta-V of ships:

I think (just an approximation) that the main thruster of my Cobra III does around five gees (that is, around 49m/s/s). If I remember correctly, the fuel consumption is around one tonne per hour, and the fuel tank capacity is 16 tonnes, so that gives us 16*3600=56700 seconds of acceleration at five gee. 56700*49=2 822 400, or around 2800 km/s, almost 1% of c. Not bad! Still a few centuries to reach the nearest known star (besides Sol of course ) but a lot better than anything we have today.

 

[OnePercent]

It will be massively disappointing if it is a cut scene. That will ruin the whole thing for me.

RATO packs would be cool....



Fail to see how we wouldn't be masslocked on the planets surface, without a massive fudge, lol

The same way we're mass locked by giant asteroids, we fly away from the surface a bit then our FSD can kick in. This would be quite easy going at average 300 m/s

 

[Space Fan]

"Delta-v (literally "change in velocity"), symbolised as Δv and pronounced delta-vee, as used in spacecraft flight dynamics, is a measure of the impulse that is needed to perform a maneuver such as launch from, or landing on a planet or moon, or in-space orbital maneuver. It is a scalar that has the units of speed. As used in this context, it is not the same as the physical change in velocity of the vehicle."

So it is related to the exact discussion we're having. You and I are saying the same thing in different words; don't go trying to tell me mine aren't relevant when I know darn well that they are. Although tbh my own quote seems internally contradictory; first it says it literally means "change in velocity", then goes on to say that it is the measure of the impulse that is needed to perform a maneuver, then says it is NOT the same as the physical change in the velocity of the vehicle, which sounds like the last phrase of the sentence flies in the face of the first.

No matter. I'm sure my understanding of it is not complete, but I understand enough to know that it IS very relevant to the discussion: a ship that can maintain the levels of thrust that the ships in E : D do for as long as they maintain it--at least a full day under thrust, maybe more--CAN do what you and I both say is possible, and the sentence "they have enough delta-V to accomplish it" is exactly accurate.

I don't know where you got that chip on your shoulder about the expression "Delta-V" but it's wrong and you need to let it go.

The *specific* impulse (Impulse *per mass*) of a rocket ship is indeed a measure of the final resulting velocity change of the ship - but not the 'impulse'. And the units of *specific* impulse are indeed metres per second.

And you are absolutely right, the specific impulse *is* a good measure of rocket capability. And at the moment, chemical engines provide a poor specific impulse. Fuel concerns are of importance, and the specific impulse of ED ships (although fictionary) is very large - there are no problems with planetary take-off that I can see.

I admire your understanding - it is really all this talk of 'escape velocities' - the title of this thread - that is affecting my sanity!

My apologies.

Edit: someone just mentioned escape velocity - again! - good god! Please stop

A final note on the dreaded 'Escape velocity': an example: *if* there were no atmosphere, and *if* you could somehow hurl a rocket ship in some giant sling upwards at the escape velocity - it would escape Earth's gravitational influence all the way to infinity - with no engines! But we *don't* hurl them like rocks, because: 1. It would kill the crew 2. The ship would burn up at that speed in the atmosphere 3. It is just not practical.

So we don't do this, we fit them with engines, which makes the dreaded 'escape velocity' just an arbitrary measure of the grav potential of a planet - and of no real engineering value..

 

[OnePercent]

There is no such thing as "orbits" in elite dangerous, When you're approaching any point of interest in a solar system and you're locked on the game automatically adjusts your velocity to match the orbit velocity of that POI then when you drop out the game makes you stay in that orbit with a station, astroid belt, planet rings, salvage around a star...anywhere.

The mechanic as i expect will be very similar to how we currenly drop out of rings, stations.

You just supercruise down to the surface and then drop out of SC some number of kilometers above the ground and then fly the rest in m/s
I expect the supercruise minimum speed would be reduced to 1 kilometer per second and a 4th and 5th layer of precision added to the game

 

[Space Fan]

Yeah, I don't know what Impulse is, outside of Star Trek. Or didn't, I'll accept your explanation. I know about Delta-V from reading a Poul Anderson book that was fairly hard sci-fi. Wish I could take your physics class but I'm a tad bit old. Also I ask too many questions in class and you'd never get anywhere. Oh, that explanation I quoted was from Wikipedia.

Fuel concerns are of importance in 2015. But if you're using nuclear fusion for power and the helium that comes out of your reactor as reaction mass, I can easily see it being nowhere near as much of an issue in 3301.

Thanks for your forgiveness. Well here's a quick explanation (cigarette packet back type)

Newton's 2nd states F=ma. But acceleration, a, is basically velocity change per time, (delta-v)/t. So instead of writing F=ma, we could write F=m x (delta-v)/t. Multiply both sides by time and we get:

Ft = m x delta-v.

This Ft on the left (thrust force x time) *is* the impulse! Impulse per mass would be Ft/m, so rearranging slightly we're left with: Ft/m = delta-V

So there's your delta-V - as you correctly say, a good measure of the quality of a rocket's engines in relation to the tons of metal it has to push about..