Orbiter being introduced into the atmosphere.

[Urwumpe]

On the odd occasion I feel the need for atmospheric flight, Flightgear fits the bill and the price is just right too

Flightgear is just cool and also looks really good. But the performance is still not too good on my PC. By GPU is adequate I would say, but my CPU is a bit too weak.

Also, the planes could need some visual improvements.

 

[Thunder Chicken]

Well, there is also the problem that most spacecraft in Orbiter don't model this drag (high Knudsen numbers) correctly. And I am not sure if Orbiters physics engine can integrate such low accelerations correctly.

There are correction factors available for Knudsen number effects, but they are good only for a certain regime - they fail at Knudsen numbers where you really must start modeling gas molecules individually instead of as a continuous gas. And as you say, it would be very hard for Orbiter to maintain accuracy for such small accelerations over long periods of time.

It is very difficult to predict the effects of this drag. Skylab is an example - it was very difficult to predict when and where it would finally re-enter. They simply had to determine the present location, then make an estimate of the drag and extrapolate, and continue to refine right up until re-entry.

 

[Sherrif of Nottingham]

Man, this addon would destroy my VLEOSS (Very low earth orbit space station) because a small linear burn would send it into the atmosphere already. Just imagine if the Exoatmosphere was modeled...

 

[Urwumpe]

Man, this addon would destroy my VLEOSS (Very low earth orbit space station) because a small linear burn would send it into the atmosphere already. Just imagine if the Exoatmosphere was modeled...

Then you would need the same solution as GOCE uses. A small electrical thruster for providing drag compensation.

 

[Sherrif of Nottingham]

heh... the station is about the size of the ISS(and MIR), I'd give a picture but my print screen function is messed up ever since I locked down my computer. I really don't know why?

 

[simonpro]

Well, there is also the problem that most spacecraft in Orbiter don't model this drag (high Knudsen numbers) correctly. And I am not sure if Orbiters physics engine can integrate such low accelerations correctly.

True, but IMO something is better than nothing.

Ah that's a shame. I still have it, but only the DLL (Earth.dll), no sources. I still haven't got around to properly test it ...:blush:. But if you lost the sources, I am not sure how much good the DLL will be.

No worries. I might have the source somewhere (my old laptop is probably in a cupboard in my office) so I'll see if I can dig it out next time I'm home.

 

[Urwumpe]

True, but IMO something is better than nothing.

True, better a round in the pub, than a thin in the bed. :lol:

I wish we would have something like SCARAB for Orbiter, at least from the aerodynamic part of it. The High atmosphere aerodynamics for satellites are simple enough to calculate them from mesh files.

 

[joeybigO]

We had seriously discussed this before.

I forgot which beta I was a part of, and I do remember that some of the basic numbers for drag were computed, and therefore Dr. Martins introduced the basic model of drag and orbit peterburations.

One thing to think about is with the shape and computational numbers of the wings within each ship, even though it flies through the air like a rock, it is still considered a wing. So you would have to calculate a Reynolds Coefficient for each wing, or lifting body (not sure if thats the right term).

The computational component of drag is a simple formula, that proves worthwhile. I think its like D= .00000247 A/V (or something like that).

Anyways, just though I would give you all something to think about.

 

[Sherrif of Nottingham]

SCARAB? Is that like a digital wind tunnel for 3D CG models? It calculates wind forces upon it?

Oh well, the deal would be that Orbiter itself needs the capabilities of collision too, then use the same collision models for Aerodynamics.

I dream about Orbiter Collision sometimes, just imagine bouncing of the ISS solar panels, because you were an idiot.

I was using Velcro Rockets, and never put on any fairings before because I was too lazy and it didn't matter.

Brings me to another point, if I put a fairing around a payload, then the inside of the cone shouldn't be affected by Aero's. But this all goes back into collision, if the fairing exists, technically you shouldn't have to strap down the payload, unless you want it to achieve orbit in one piece.

 

[Urwumpe]

SCARAB? Is that like a digital wind tunnel for 3D CG models? It calculates wind forces upon it?

SCARAB = S/C atmospheric re-entry and aerothermal break-up.

A huge complex software suite designed for predicting reentry aerodynamics and reentry heat damage. Is used for predicting the ground damage by uncontrolled reentries.

 

[Sherrif of Nottingham]

oh...

Oops...

Anyway;
This stuff would be great, anything for realism.

 

[Arrowstar]

I honestly don't feel the need to simulate weather conditions and whatnot too terribly much in Orbiter as:
1) I would never launch/land in a condition that would be dangerous for the vehicle and crew, and
2) I spend all my time in space, anyway!

However, 'exoatmosphic drag' (for lack of a better term ) is something I wouldn't mind seeing modeled by the Orbiter core. Or perhaps someone could write a generic DLL for all atmospheres...