General Question Venus Landing in XR2?

[Epsilon]

It's actually quite possible to land an XR2 on Venus if you're -careful-.
The surface temp on Venus is 478.2C if I remember right. The XR2's insides start failing at 480C. This gives you a -very- small margin, but you'll float down the last couple hundred meters, so honestly, you can drop your gear about 100 feet from the surface, and you'll still come down fairly gently with minimal (25m/s) forward speed. It's actually quite an interesting challenge - I did it (and detailed it) on the first portion of my "Paradox Grand Tour" over in the flights forum - you can check it out.
On the other hand, the others are correct - you're going to have to remove the pressure sensitivity from the rocket engines - in "realistic" terms, you can "install" some sort of jet engine, a propellor, or something to that effect to allow you to take it off.
One thing to watch for: I found that it's -extremely- difficult to make a rolling takeoff - I had to use hover engines to get myself up enough to close the gear, and then after that I could engage the mains to get me moving forward. Keep your speed down while you're climbing - it's easy to peg your DynP on ascent and make stuff start breaking.

 

[tylor2000]

Aviation uses it like that because that's what it means...

I just looked it up in the dictionary and you are right. I guess I just never have heard the term used in anything other that in rockets, and assumed the use in aviation was an oversimplification.

When I was talking about it not using thrust I was thinking in terms of the simulator anyway and making it a lift element. Does air actually move in orbiter? If it doesn't move is there really any thrust? Ok, I'll be quiet.

 

[Hielor]

I just looked it up in the dictionary and you are right. I guess I just never have heard the term used in anything other that in rockets, and assumed the use in aviation was an oversimplification.

When I was talking about it not using thrust I was thinking in terms of the simulator anyway and making it a lift element. Does air actually move in orbiter? If it doesn't move is there really any thrust? Ok, I'll be quiet.

Ah, I was actually typing the response to that in my post, but guess you didn't see it in time--I really should just add a reply, rather than editing.

Here it is again anyway:

I'm fairly sure that you wouldn't be able to make the airfoil on a propeller move through the air in any meaningful fashion that would allow Orbiter to natively simulate a propeller. To simulate a propeller you'd probably be better off having a rocket on which you control the thrust parameters in order to simulate the thrust generated by a rotating propeller -- it's not particularly accurate and it would be terribly hard to code, but I think that's the best we'd be able to do at this point.

 

[docabn]

Apart form temperature. The ability for a airframe which was designed to keep a pressuriezed atmosphere in might have a significantly more difficult time keeping out an atmosphere that is 90 earth atmospheres. I don't believe that sort of damage recording hasn't been implimented (if it has please let me know where to download the addon) but I will have to check and see if I experience higher than normal wing stress.
As for propellers if orbiter actually supported them, I believe they would be greatly more efficient, but they would require a lot more energy and would be subject to serious overheating issues.
As such a lifting vehicle that was prop-based would probably be pretty realistic (if you assume we solved the temperature,pressure, and engine design problems) and should get higher than your average prop-based airframe on earth.

Two other (realistic) problems with the atmosphere of venus; the atmosphere is highly corrosive, and 300+ km winds

As for just propellers a craft could be designed have an animation of roatating props but the actual effect would be the same as any other craft just a measure of thrust against mass against gravity.
Because we've all seen it done(ex. scram engins) the prop engines could be less effective as air pressure dimminishes.
It wouldn't be as realistic as say a flight sim designed to deal with this but I think it could be made to work. (note: I'm not very good at programming so while I think it could be done I have no real idea how difficult this might be)

 

[tylor2000]

Ah, I was actually typing the response to that in my post, but guess you didn't see it in time--I really should just add a reply, rather than editing.

Here it is again anyway:

I'm fairly sure that you wouldn't be able to make the airfoil on a propeller move through the air in any meaningful fashion that would allow Orbiter to natively simulate a propeller. To simulate a propeller you'd probably be better off having a rocket on which you control the thrust parameters in order to simulate the thrust generated by a rotating propeller -- it's not particularly accurate and it would be terribly hard to code, but I think that's the best we'd be able to do at this point.

Yeah I was thinking that actually. I'd have to look at the problem and maybe figure it out. I still am working on my airfoil analysis and all that. I don't even know when I'll be done with that. It could be some kind of animation. Just so you know I never expected for anyone to ACTUALLY do this or dump work on someone. I could probably figure out how to do it in a few weeks. But I haven't even finish even one add-on and I'm a bit of a newbie at doing all that for orbiter.

---------- Post added at 12:12 AM ---------- Previous post was at 12:02 AM ----------

Apart form temperature. The ability for a airframe which was designed to keep a pressuriezed atmosphere in might have a significantly more difficult time keeping out an atmosphere that is 90 earth atmospheres. I don't believe that sort of damage recording hasn't been implimented (if it has please let me know where to download the addon) but I will have to check and see if I experience higher than normal wing stress.
As for propellers if orbiter actually supported them, I believe they would be greatly more efficient, but they would require a lot more energy and would be subject to serious overheating issues.
As such a lifting vehicle that was prop-based would probably be pretty realistic (if you assume we solved the temperature,pressure, and engine design problems) and should get higher than your average prop-based airframe on earth.

Two other (realistic) problems with the atmosphere of venus; the atmosphere is highly corrosive, and 300+ km winds

As for just propellers a craft could be designed have an animation of roatating props but the actual effect would be the same as any other craft just a measure of thrust against mass against gravity.
Because we've all seen it done(ex. scram engins) the prop engines could be less effective as air pressure dimminishes.
It wouldn't be as realistic as say a flight sim designed to deal with this but I think it could be made to work. (note: I'm not very good at programming so while I think it could be done I have no real idea how difficult this might be)

Yeah, I agree...as in my last post. I just didn't read yours before I posted it. Other animated control surfaces have a solid structure as it moves. Knowing computerex he could probably write it in 15 minutes partially because he has lots of experience with orbiter.

---------- Post added at 12:28 AM ---------- Previous post was at 12:12 AM ----------

What do you guys use for turbofans on the airliners? I was thinking of using those, but it is probably just a adjusted isp and such things.

 

[Hielor]

Yeah, I agree...as in my last post. I just didn't read yours before I posted it. Other animated control surfaces have a solid structure as it moves. Knowing computerex he could probably write it in 15 minutes partially because he has lots of experience with orbiter.

What do you mean, "have a solid structure as it moves"? Do you mean like how ailerons/elevators affect the pitch or roll of the craft? That's a simple change in the lift produced by the wing. For a simulated propeller, I imagine it would be easier to represent it in Orbiter as a rocket engine, since that's the only type of thrust that it recognizes. Airfoils in Orbiter are calculated with respect to the vessel's motion through the air; it's not designed to handle airfoils that aren't fixed.

Plus, the propeller is spinning at (often) upwards of 2000 RPM -- for lower framerates, the propeller could be moving through a full revolution (or more) per frame. It would be far simpler to use a rocket engine (with no visible exhaust, of course) and manually (in the dll) account for such things as p-factor and torque.

Or do you just mean the animation of the propeller itself? At high speeds, you'd just want it to be a blur, so you'd use a translucent disc for the model rather than an actual model of a propeller...

---------- Post added at 12:36 AM ---------- Previous post was at 12:35 AM ----------

What do you guys use for turbofans on the airliners? I was thinking of using those, but it is probably just a adjusted isp and such things.

Jet engines are simulated as rocket engines which are heavily affected by atmosphere.

 

[tylor2000]

What do you mean, "have a solid structure as it moves"? Do you mean like how ailerons/elevators affect the pitch or roll of the craft? That's a simple change in the lift produced by the wing. For a simulated propeller, I imagine it would be easier to represent it in Orbiter as a rocket engine, since that's the only type of thrust that it recognizes. Airfoils in Orbiter are calculated with respect to the vessel's motion through the air; it's not designed to handle airfoils that aren't fixed.

Plus, the propeller is spinning at (often) upwards of 2000 RPM -- for lower framerates, the propeller could be moving through a full revolution (or more) per frame. It would be far simpler to use a rocket engine (with no visible exhaust, of course) and manually (in the dll) account for such things as p-factor and torque.

Or do you just mean the animation of the propeller itself? At high speeds, you'd just want it to be a blur, so you'd use a translucent disc for the model rather than an actual model of a propeller...

---------- Post added at 12:36 AM ---------- Previous post was at 12:35 AM ----------


Jet engines are simulated as rocket engines which are heavily affected by atmosphere.

It could just be a really good texture that barely quivers back and forth while an invisible mesh in the background doing all the work. plus with a mesh you can assign more than one airfoil to it so with every revolution you could have an "x" as many airfoils working at the same time. Soooo...if you were to have them move 10 revolutions per second and you assigned 20 of them to do so then you would have a simulated 200 rpms., ect., ect.

---------- Post added at 01:58 AM ---------- Previous post was at 01:47 AM ----------

Plus,it could be a really simple mesh so would the mesh itself wouldn't effect frame rates, even though the designated airfoils might. With such a simple mesh it could probably rotate faster with no or little effect on performance....meaning less defined airfoils.....or the associative property of that.

---------- Post added at 02:04 AM ---------- Previous post was at 01:58 AM ----------

I'm thinking right now of course about a prop that would be encased inside a housing. A normal exposed prop could have something similar.

---------- Post added at 02:28 AM ---------- Previous post was at 02:04 AM ----------

When someone with prop makes his vessel.ddl I'm pretty sure he could program in using C++, a control for throttle structure or loop. We could build a standard to make it easy for everyone. I'm not sure but I'm pretty sure that would be fairly easy depending on how everything is set out. (see I don't know that part yet)

 

[Hielor]

It could just be a really good texture that barely quivers back and forth while an invisible mesh in the background doing all the work. plus with a mesh you can assign more than one airfoil to it so with every revolution you could have an "x" as many airfoils working at the same time. Soooo...if you were to have them move 10 revolutions per second and you assigned 20 of them to do so then you would have a simulated 200 rpms., ect., ect.

---------- Post added at 01:58 AM ---------- Previous post was at 01:47 AM ----------

Plus,it could be a really simple mesh so would the mesh itself wouldn't effect frame rates, even though the designated airfoils might. With such a simple mesh it could probably rotate faster with no or little effect on performance....meaning less defined airfoils.....or the associative property of that.

---------- Post added at 02:04 AM ---------- Previous post was at 01:58 AM ----------

I'm thinking right now of course about a prop that would be encased inside a housing. A normal exposed prop could have something similar.

---------- Post added at 02:28 AM ---------- Previous post was at 02:04 AM ----------

When someone with prop makes his vessel.ddl I'm pretty sure he could program in using C++, a control for throttle structure or loop. We could build a standard to make it easy for everyone. I'm not sure but I'm pretty sure that would be fairly easy depending on how everything is set out. (see I don't know that part yet)

Again...

Orbiter's airfoil implementation natively only supports fixed airfoils. You can't have a rotating airfoil and have Orbiter apply lift to it currently, not without a lot of extra work.

It would be far better and easier to simulate it through an Orbiter rocket engine (which really is just a "thrust attack point"), and calculate the thrust that should be delivered (and where) based upon the combustion engine's parameters and propeller's parameters.

 

[Linguofreak]

Two other (realistic) problems with the atmosphere of venus; the atmosphere is highly corrosive, and 300+ km winds

The winds aren't that fast at the surface, and I don't think the wind shear between levels is particularly violent, so winds shouldn't be a problem.

 

[tylor2000]

Again...

It would be far better and easier to simulate through an Orbiter rocket engine (which really is just a "thrust attack point"), and calculate the thrust that should be delivered (and where) based upon the combustion engine's parameters and propeller's parameters.

As you have reiterated through the whole thread. Live a little! I can still be able to do this. You probably have a huge rocket in your front yard....sheesh. Learn to live outside the rocket!

I want to be able to do this for a particular function where rockets won't work! Outside the rocket I tell you!

 

[Hielor]

As you have reiterated through the whole thread. Live a little! I can still be able to do this. You probably have a huge rocket in your front yard....sheesh. Learn to live outside the rocket!

I want to be able to do this for a particular function where rockets won't work! Outside the rocket I tell you!

The only way to generate thrust in Orbiter is to use rockets. Really though, the API is "loose" enough that you can use an Orbiter thruster to simulate any kind of thrust-generating apparatus, including a propeller. It has been used many times by many people for SCRAM engines, for example.

You are, however, welcome to attempt to use airfoils to simulate a propeller in Orbiter. Be sure to let us know how well it works.

 

[John_L]

If Orbiter (or an add on module) models buoyancy, things would get easier. You could inflate a balloon with hydrogen, helium, or even air would be an efficient lifting gas on Venus, and float your way up to an altitude where thrusting would be efficient enough to allow you to make it up into orbit. So, from a more conventional standpoint, it would be impossible, but thinking outside the 'box' of brute force thrust, it would not only be possible, but probably more efficient than taking off from earth, and easier. This of course assuming your craft could handle the extreme temperatures, pressures, and corrosive environment at surface level.

Because the atmosphere is so dense, one could put a balloon base, and fly airships around as well in the higher, less dense, and cooler region of the atmosphere.

 

[Hielor]

If Orbiter (or an add on module) models buoyancy, things would get easier. You could inflate a balloon with hydrogen, helium, or even air would be an efficient lifting gas on Venus, and float your way up to an altitude where thrusting would be efficient enough to allow you to make it up into orbit. So, from a more conventional standpoint, it would be impossible, but thinking outside the 'box' of brute force thrust, it would not only be possible, but probably more efficient than taking off from earth, and easier. This of course assuming your craft could handle the extreme temperatures, pressures, and corrosive environment at surface level.

Because the atmosphere is so dense, one could put a balloon base, and fly airships around as well in the higher, less dense, and cooler region of the atmosphere.

There's an addon on OrbitHangar that models buoyancy.

 

[Tommy]

Because the atmosphere is so dense, one could put a balloon base, and fly airships around as well in the higher, less dense, and cooler region of the atmosphere.

I mentioned this add-on earlier:

[ame="http://www.orbithangar.com/searchid.php?ID=3488"]Shukra_Venus_Station_080813[/ame]

Note: a specially designed Venus lander could take advantage of the buoyancy provided by the lower pressure (and density) of the atmosphere inside the hull. Coupled with electric powered ducted fans, etc.

 

[docabn]

It would have to be one sturdy baloon but sure hydrogen would be very efficient in that sort of atmosphere so long as it could survive the corrosive atmosphere and winds. A donut torus ballon might work best for a vertical launcher. more zeplin like for a DG style airframe. (does Venus have lightning if so maybe helium)

 

[destinos]

With the ship buttoned up for reentry, the surface temps weren't a problem. But the temp limits with gear deployed are lower than the reentry configuration limits. So trying to land turned out to be a rather bad idea.

I just gave this a go and was able to put a DGIV down safely. I waited until just before touchdown to lower the gear, and by that time i couldnt have been going more than 20-25 m/s. The atmosphere was like gel! On landing I was even able to EVA one of the crew. the hull temp alarm did go off when i opened the nose cone but there didn't seem to be any damage done. When I tried to take off, the gear snapped off pretty immediately. I guess because its dynamic pressure(?) tolerance is so low. In the end I left the three of them to die, alone and terrified on the surface, and headed for Mercury, their cries for mercy echoing after me in the inky blackness.

 

[Sky Captain]

What about nuclear pulse rocket would it work on Venus? I think it should since the thrust is generated when shockwave impacts the blast shield and denser atmosphere would help to create more powerful shockwawes, but I`m not quite sure, maybe there would be some other limiting factors?

 

[Artlav]

What about nuclear pulse rocket would it work on Venus? I think it should since the thrust is generated when shockwave impacts the blast shield and denser atmosphere would help to create more powerful shockwawes, but I`m not quite sure, maybe there would be some other limiting factors?

Shockwaves are the problem. Your ship will be smashed into a crumpled ball of hullmetal, most likely. Also, back-drag - even if it survives the shock, the explosion will be like a depth charge - the air will go up, then back down, and your ship will barely move at all.