Idea Lighter than air framework

[Linguofreak]

A while back Artlav put out his Shukra station addon, which is a station in the Venusian atmosphere supported by baloons. It strikes me that, for fictional Venus missions (or for real-life probes like Vega 1 and 2) it might be useful to have a standard framework for making vessels that can deploy baloons and function as lighter-than-air craft.

Desirable features for such a framework would be:

*Usability for both config-file and DLL based addons.

*The ability to deploy and release baloons. Deployment would be needed so that the baloons can be in a stowed state during launch, spaceflight, and atmospheric entry, rather than being out all the time and requiring the vessel to be already in atmosphere on the target planet at the beginning of the scenario. Release would be needed to allow ascent stages to cut loose from their baloons and launch to orbit.

*Gas management for baloons, to allow control of bouyancy, and possibly define a bursting mechanic if players mismanage gas pressure.

*The ability to define various extendable/retractable hardware (to allow for atmospheric entry in a clean state followed by deployment of the hardware), such as:

-UMMU walkable platforms, so that UMMUs can EVA without falling to their deaths.

-Propulsion equipment, most likely of a solar-electric propeller-driven nature.

-Docking poles/arms, to assist in assembling modular lighter than air vessels, since real-life baloons will generally come into contact before the heavier-than-air eqipment they support, making it hard to attach those bits of equipment to each other. In Orbiter, of course, there's no vessel-vessel collision mechanic, but baloons interpenetrating will look silly, so defining equipment that can be used to pull the heavier than air portions of two lighter than air vessels together while fending the lighter than air portions off from each other will be useful.

*The ability to define tracks for the attachment points of baloons to move along while the baloons are deployed. For example, returning astronauts to orbit from the Venusian atmosphere would require a launch vehicle on the scale of what we use for manned launches from Earth. It would likely be necessary to attach one or two stages together, plus a manned capsule. The assembly of the launch vehicle would probably most easily be done horizontally, with each stage supported by a baloon at either end, but the launcher would need to be moved to a vertical position before launch. This would involve sliding the attachment points for the baloons on each stage to the top of the uppermost vehicle on the stack.

*Shukra has a feature that locks it to a position over a constant lattitude and longitude at high time acceleration. Something like this, with the ability to work on docked groups as well as single vessels, would be nice, possibly locking the vessel to a preset course rather than a single location if propulsion equipment or a planet module with non-zero wind speeds is involved.

Thoughts?

 

[Andy44]

I once had an urge to build a Zeppelin add-on, and an Empire State Building with working docking mast to go with it, but there was no easy way to model bouyancy. This would be cool.

 

[Linguofreak]

I once had an urge to build a Zeppelin add-on, and an Empire State Building with working docking mast to go with it, but there was no easy way to model bouyancy. This would be cool.

Artlav did it somehow with Shukra, though it may have been just a matter of getting the thing to hover 100 km up more than actual bouyancy.

 

[Izack]

There would be a couple of ways to do this. One could calculate air density from in-sim data and use AddForce, though this would be unstable. [ame="http://orbithangar.com/searchid.php?ID=5092"]Has been done[/ame]. The other way, if I remember correctly the way Shukra did it, was by setting altitude directly.

Regarding vessels floating at Venus, it was mentioned recently that the Deltaglider should be buoyant somewhere above Venus's surface. Yikes.

 

[sorindafabico]

Regarding vessels floating at Venus, it was mentioned recently that the Deltaglider should be buoyant somewhere above Venus's surface.

With some airspeed, I suppose.

 

[Linguofreak]

There would be a couple of ways to do this. One could calculate air density from in-sim data and use AddForce, though this would be unstable. Has been done. The other way, if I remember correctly the way Shukra did it, was by setting altitude directly.

Regarding vessels floating at Venus, it was mentioned recently that the Deltaglider should be buoyant somewhere above Venus's surface. Yikes.

Well, if filled with STP air, yes. But in that case it's probably reasonable to expect it to reach crush depth first.

 

[Loru]

I like the concept. I've been playing bi with idea of autonomus/RC blimp probe (concept similar to one seen in Discovery's "Alien Planet" documentary.) As for UMMU walkable areas I think it would be wise to wait bit more. In recent video posted by Martins we saw working collision detection with ground. If API is updated then same engine can be used for this.

 

[4throck]

Good idea if it models atmospheric temperature and pressure.

If i remember correctly, the Mars blimp projects uses the daily thermal cycles + solar power to make the vessel ascend during the day and descent during the night. That would be fun to recreate.

But it would only function with atmospheric simulation down to general winds and ascending / descending currents. Also, there's some relation to topography / altitude.

Well worth having. Probably it could be used to simulate the a Titan boat...

 

[Linguofreak]

I guess now the question is whether anybody has the time, resources, and interest to develop this. I understand perfectly well if no one does, as, after all, if I had the time or the resources this would be under "Addon development" rather than "addon requests".

So, any takers?

 

[sorindafabico]

There would be a couple of ways to do this. One could calculate air density from in-sim data and use AddForce, though this would be unstable.

Perhaps this might be useful as a starting point. I did a test with vessel density = 1 and it stayed around air_density=1 altitude. Feel free to improve the code if you find it useful (I don't know if it can be more stable than this, probably YES...):

void balloon::clbkPreStep (double simt, double simdt, double mjd)
{
	VECTOR3 gforce, unit_grav, vector_empuxo;
	
	GetWeightVector(gforce);
	double gravity = sqrt(pow(gforce.x,2)+pow(gforce.y,2)+pow(gforce.z,2));
	double g=gravity/GetMass();
	double air_density=GetAtmDensity();
	double air_mass=air_density*volume;
	double empuxo=air_mass*g; // thrust

	unit_grav=gforce/gravity; //unit vector
	vector_empuxo=-unit_grav*empuxo; // thrust being always opposite to gforce

	if (grounds==SOLTO){
		AddForce(vector_empuxo,_V(0,0,0));} // "SOLTO" = balloon isn't tied to the ground

}

 

[4throck]

If it doesn't involve interaction with the user then a simple LUA script can handle this....

 

[JonnyBGoode]

There used to be a bouyancy.dll module that simulated this. There was a Jovian atmosphere probe that utilized it. But I think the DLL broke with the 2010 release.