[Baron MacDoblin]

I don't necessarily see the connection between "ships can fly in atmosphere" and "fighters can fly in atmosphere" :\ In fact, I'd think it'd make less sense, since all the work made to make fighters streamlined and atmospheric-capable could be used to make a better pure SPACE FIGHTER, period.

[Drew]

Originally posted by Baron MacDoblin
In fact, I'd think it'd make less sense, since all the work made to make fighters streamlined and atmospheric-capable could be used to make a better pure SPACE FIGHTER, period.

but a little unecsessary... there is no need for streamlining in space cuz (obviosuly) there is almost no friction of any kind...

[Baron MacDoblin]

Exactly.

[Flaser]

Escape velocity and leaving a planet are wrongly connected with one another!

The reason why they speak of EV is that any object that has reached that speed has enough kinetic enegy to leave Earth orbit.

On the other hand all you need is enough energy to lift you out of orbit. It doesn't matter at what speed you achieve it.

[Goober5000]

Originally posted by Flaser
The reason why they speak of EV is that any object that has reached that speed has enough kinetic enegy to leave Earth orbit.

Any object?  But KE is partially dependent on mass.  How do they calculate that?  (I assume the mass cancels out somewhere in the equation?)

[Flipside]

I think what Flaser is saying is that as long as your velocty away from the centre of gravity is higher than the gravitic pull (in Earths case about 9.8 m/s/s) then you are at escape velocity, so if you are going upwards at a constant 10m/s then you are at escape velocity, however the reason we have to go so fast is so the rocket doesn't run out of fuel

Flipside

[Goober5000]

Flipside, your post doesn't make any physical sense.  You can't have "velocity higher than acceleration"... they're two different concepts.  If you're moving at a constant velocity, you have zero acceleration... therefore you are not exerting any force, and Earth's gravity will pull you back down to the ground.

"Gravitic pull" = downward force = mass * acceleration

Kinetic energy = 1/2 * mass * velocity^2

You need to have enough energy to overcome the force... the problem is, I'm forgetting the equation that relates the two.  That's why I asked Flaser to elaborate.

[Sandwich]

Escape velocity is the speed a theoretical object would need to attain from "sea level" in order to escape a planet's gravitational pull, if that object had zero friction with the atmosphere. EV is purely to measure the velocity needed to escape the gravitational pull, nothing more.





....AFAIK.

[Solatar]

I always thought that fighters were streamlined was that shrapnel, bullets, and space debris bounce of curved stuff better than blocks (stuff would slide off a circle, but penetrate a cube).

[Flaser]

The reason I spoke of EV is that the force with which Earth pulls an object depends on its mass.
However accelration is also dependent of mass - so in the end, AT A GIVEN DISTANCE ALL OBJECT HAVE the SAME ACCLERATION.

F=f*m*M/R^2

F=forcer, f=gravitic constant, m=the mass of one of the bodies, M=the other object's mass, R=the distance of the two objects

Also any force:
F=a*m
so for the body with m-mas:

a=F/m

so

a=f*M/R^2

Notice that the bodies acceleration in the gravitic field doesn't depend on its own mass.
(however the other object for instence Earth acceleration does, however the difference is so huge between any orbiting object and a planet that the effect is negliable)
This is a constantly changing force.

The energy to escape from the gravitic wells is the ammount of energy the gravitic force would take in infinity (Why infinity? There's no such thing as limit of gravitation's reach, it is just extremely small over huge distances, the same goes for any EM field, to get the proper ammount of energy we have to calculate with this distance)
This energy can be calculated, to do so we have to integrate the work of the gravitic force.

so the potential energy is

W=f*M*m*INT(1/R^2)*dR=-(R*f*m*m)/R

Between to energy levels of the gravitic field:

The radius of the two levels (the distance from the source of the field) are Ra and Rb, where Ra is closer to the source.


W=f*M*m/Ra-f*M*m/Rb

In point A if your object has enough kinetic enegy to cover that (and air frition if youmove in air) and a little more, then you can reach point B.

[Sandwich]

...and in English?

Speaking of which, where's CP been? He hasn't posted since.... November 27th...

[Setekh]

November 27? You mean, 25 days into the future? Wow.
I thought I saw him online a few minutes ago.

[Sandwich]

Bah. You know what I meant.

[SuperCoolAl]

red outs\black outs arent possible in space as they rely on G forces and there's no gravity in space

[kasperl]

oh no.
no offence, but what level of physics do you have?

[Lynx]

Hehe. Ever heard of inertial forces.

[Flaser]

No gravity in space?!?!!!!!!


That's freakinn stupid!

Tell me if there's no gravity in space what keep planets on their track?

There is no weght in a sapceship orbiting something or floating in vacum, because it accelerates or moves just as you do.
The very moment any of the thrusters kicks in you'd remedy your statement, 'casue for a military grade accelration you'd feel like 4G of acceleration smashimg you like a potato under my boot's heel.

[karajorma]

Originally posted by SuperCoolAl
red outs\black outs arent possible in space as they rely on G forces and there's no gravity in space

And this sort of comment is why that phrase about a little knowledge being dangerous was invented.

G-forces do exist in space. Think of it this way. When you turn a corner in a car quickly you get pulled to the sides. If gravity alone causes G-force wouldn't that mean that the entire Earth is now beside you rather than underneath you?

[StratComm]

And I really thought we dealt with that one a long time ago.  This thread is only 4 pages long, why don't people read the whole thing when they post something like that?

"G" as a unit of force (actually a unit of acceleration as the force would depend on the mass going throught the turn) is somewhat like "atmosphere" as a unit of pressure, in that both are based on the conditions we experience on a daily basis as their point of reference.  It relates to the magnitude of acceleration due to gravity at the surface of the earth.  The strength of a force in a turn is in no way related to the gravitational field at that particular point in space, so to say that you need gravity to produce a "G" force is simply not correct.

[SuperCoolAl]

okay, okay im an idiot ure right etc...

i just hate sifting thru 4 pages when i get so little time on this particular computer

anyway who cares if its against the laws of physics- freespace IS against the laws of physics!