OFMM Development: Atmospheric Vessels

PhantomCruiser

Wanderer
Moderator
Tutorial Publisher
Joined
Jan 23, 2009
Messages
5,537
Reaction score
95
Points
138
Location
Cleveland
That's the Ares craft I had mentioned in a (now) different thread. I figured that it could be unpackable and deployed from the landing site for surface exploration.
 

Izack

Non sequitur
Addon Developer
Joined
Feb 4, 2010
Messages
6,665
Reaction score
13
Points
113
Location
The Wilderness, N.B.
That's the Ares craft I had mentioned in a (now) different thread. I figured that it could be unpackable and deployed from the landing site for surface exploration.
That thread is now titled OFMM General Discussions. Otherwise, it's the same thread as before.

I was wondering what the heck that plane was. Do you know what its mass is? I like the idea of flying around Mars in a plane, if it's possible in the thin atmosphere. It would solve the dilemma of using an unsafe rocket ship or exceedingly slow rover, too, as well as introducing another new aspect to the mission.
 

fireballs619

Occam's Taser
Donator
Joined
Nov 4, 2009
Messages
788
Reaction score
4
Points
33
I would be in favor of using the plane, if its mass is lower than (or at least not significantly larger) than that of the rover. I think we should have a SMEV that has a low mass, so we can bring multiple with. If we are going to have 10-20 astronauts on the surface, it wouldn't be efficient to bring only one 2 person vessel. Perhaps a rover and a plane are in order?
 

Bj

Addon Developer
Addon Developer
Donator
Joined
Oct 16, 2007
Messages
1,886
Reaction score
11
Points
0
Location
USA-WA
Website
www.orbiter-forum.com
Perhaps a rover and a plane are in order?

Sounds good, only thing I have to challenge is if it is capable of 'gliding' on Mars (wing size & weight) Would a UAV be able to actually work on Mars's thin atmosphere without requiring a huge wing area?

Something like the lunar rover or (What was that one called that attaches to Arrow?) for short distances and some sort of small UAV for longer distances.
 

James.Denholm

Addon ponderer
Joined
Feb 8, 2008
Messages
811
Reaction score
0
Points
0
Location
Victoria, Australia
Personally, I would imagine a balloon-type craft to be more appropriate for such expeditionary explorations, potentially smaller (packing wise) and less complicated to operate. But I'm not sure if the thin atmosphere would be a help or a hindrance to such a method of travel.
 

Izack

Non sequitur
Addon Developer
Joined
Feb 4, 2010
Messages
6,665
Reaction score
13
Points
113
Location
The Wilderness, N.B.
What was that one called that attaches to Arrow?
Azure, and I agree. It's great.

James.Denholm said:
Personally, I would imagine a balloon-type craft to be more appropriate for such expeditionary explorations, potentially smaller (packing wise) and less complicated to operate. But I'm not sure if the thin atmosphere would be a help or a hindrance to such a method of travel.
I believe PhantomCruiser is working on just that.
 

Bj

Addon Developer
Addon Developer
Donator
Joined
Oct 16, 2007
Messages
1,886
Reaction score
11
Points
0
Location
USA-WA
Website
www.orbiter-forum.com
...skycrane, currently I even prefer having the payload enclosed inside an approximately toroidal vehicle structure, so the expendable amount of the heat shield can be reduced and the CoG is closer to the center of the vehicle.

Wait, I am getting confused... wasn't the sky crane going to be a reusable reentry vehicle almost exactly like the space shuttle. Wouldn't disposable heat shields be hard to come by?

It should be able to hover with a full load of cargo and the cargo bay doors are on the bottom. I was envisioning it to look like;

Dsc_0159%20Skycrane%20S-64E%20N6979R%20707%20Evergreen%20left%20side%20hover%20l.jpg


with the only difference that the wheel supports would be widened (so the cargo bay is more square) and have cargo doors (that also act as a heat shield) will open to drop the cargo inside, and replace the props with a square structure with rockets at each corner like;

MSR-skycrane-landing-hi-res_041014190213.jpg


Is that what you also have for a design? Or is there more to it?

I think the ideal crew size for the first iterations is 8, this is like a shuttle crew + 1 additional MS.

8 crew per hab module sounds good. Thinking about it now, how large would that need to be? The ISS has 835m^3 for 3-6 long-term people, would a module that big or bigger be able to feasibility fit on a crane? Or should the hab module be split up like the ISS? Maybe before now it was just a given and I just thought of it now..


One astronaut should be trained as in-flight surgeon, the OSHV needs to have a small medical station on-board, that is separate of the rest of the functions, out of psychological reasons. Just one bed with all the needed gear for emergency surgery, if 25% of the crew are requiring intensive medical care (2 astronauts), the situation is bad enough to switch to emergency medical situations.

I don't know if we are going to make this have any effect in the program, but it makes sense to me

Sounds good to me. Are we going to actually make our hab module actually simulate getting sick and what have you.
 

supersonic

Add-on Developer
Addon Developer
Donator
Joined
Mar 27, 2010
Messages
271
Reaction score
1
Points
0
Location
Benton
Website
fsxpilots.webs.com
8 crew per hab module sounds good. Thinking about it now, how large would that need to be? The ISS has 835m^3 for 3-6 long-term people, would a module that big or bigger be able to feasibility fit on a crane? Or should the hab module be split up like the ISS? Maybe before now it was just a given and I just thought of it now..
I would think that something fairly small would do as long as about half of the modules coming down were maned and the others unmanned.
 

Bj

Addon Developer
Addon Developer
Donator
Joined
Oct 16, 2007
Messages
1,886
Reaction score
11
Points
0
Location
USA-WA
Website
www.orbiter-forum.com
Personally, I would imagine a balloon-type craft to be more appropriate for such expeditionary explorations, potentially smaller (packing wise) and less complicated to operate. But I'm not sure if the thin atmosphere would be a help or a hindrance to such a method of travel.

According to this:

Lighter_than_air

gases that are buoyant in air because they have densities lower than that of air
I suppose it might be possible to get a density lower in a balloon than on Mars.

Using rough math


If Mars is proportional to Earth (its not but its rough estimate):
Mars has 0.0075 g/l
Helium has 0.1786 g/L;

[ame]http://en.wikipedia.org/wiki/Lifting_gas[/ame]
The lifting power in air of hydrogen and helium can be calculated using the theory of buoyancy as follows:
The density at sea-level and 0°C for air and each of the gases is:

  • Air (ρair) = 1.292 (g/L).
  • Hydrogen (ρH2) = 0.08988 g/L
  • Helium (ρHe) = 0.1786 g/L
Thus helium is almost twice as dense as hydrogen. However, buoyancy depends upon the difference of the densities (ρgas) - (ρair) rather than upon their ratios. Thus the difference in buoyancies is about 8%, as seen from the buoyancy equation:

  • Buoyant mass (or effective mass) = mass × (1 - (ρ(air)/ρ(gas)) )
0.1786 * (1- ( 0.0075 / 0.1786) ) = 0.1711

-Positive number means it doesn't float. ;)

That is at helium density at (0 °C, 101.325 kPa). How much it changes when heated/depressurized I am not sure, but if it will even float at all, it is going to be a very big balloon if it needs to hold several tonnes.

--Don't mind me, it is way past my bedtime :)
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
36,879
Reaction score
1,537
Points
203
Location
Langendernbach
Wait, I am getting confused... wasn't the sky crane going to be a reusable reentry vehicle almost exactly like the space shuttle. Wouldn't disposable heat shields be hard to come by?

It should be able to hover with a full load of cargo and the cargo bay doors are on the bottom. I was envisioning it to look like;

with the only difference that the wheel supports would be widened (so the cargo bay is more square) and have cargo doors (that also act as a heat shield) will open to drop the cargo inside, and replace the props with a square structure with rockets at each corner like;

MSR-skycrane-landing-hi-res_041014190213.jpg


Is that what you also have for a design? Or is there more to it?

Like that. The expendable heat shield idea is for solving the problem of having to land the payload while the Skycrane is above it - we could either flip the Skycrane by 180°, but this would mean that the deceleration is pulling the astronauts to the ceiling during reentry. Or we drop the bottom of the heat shield, and keep the orientation and the direction of the main acceleration vector constant. Rotating the heatshield away is worse, since this shifts the CoG, or we would need to have a split heat-shield, which sounds a bit too fantastic to me.

Sounds good to me. Are we going to actually make our hab module actually simulate getting sick and what have you.

Not sure, but we can at least keep that in mind as option. I just included the sickbay in the design as fluff requirement, since a real Mars landing would need one. So, even if we don't implement this, the volume is reserved for one.
 
Last edited:

Izack

Non sequitur
Addon Developer
Joined
Feb 4, 2010
Messages
6,665
Reaction score
13
Points
113
Location
The Wilderness, N.B.
Wouldn't exhaust particles from the Skycrane damage the hab module in the final minutes of landing? That would be easily avoided on an airless body by angling the engines away from it, but in Mars' atmosphere the exhaust would scatter less predictably.
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
36,879
Reaction score
1,537
Points
203
Location
Langendernbach
Wouldn't exhaust particles from the Skycrane damage the hab module in the final minutes of landing? That would be easily avoided on an airless body by angling the engines away from it, but in Mars' atmosphere the exhaust would scatter less predictably.

No, at least not that much, since the Hab will be tethered below the Skycrane - the distance will reduce the pressure and heat transfer.

Also, the engines will be angled away from the vertical for spreading this a bit more, at the expense of effective ISP during the landing.

I think I have a useful design done now, will make a prototype object in anim8or. If we stick to 10.8m diameter payloads, this one might need in-orbit assembly itself (not much mass, but large volume, can be combined with denser payloads), but it would be able to do the mission, be mildly realistic in technology and have a nice double-cone shape. Bad thing is just that the bottom of the payload would still need to be protected by a heat-shield. Maybe we can design a crushable expendable heat shield for the modules that acts as foundation after landing, with landing gear legs only acting as stabilization or ramp for rovers.
 

PhantomCruiser

Wanderer
Moderator
Tutorial Publisher
Joined
Jan 23, 2009
Messages
5,537
Reaction score
95
Points
138
Location
Cleveland
Regarding UAV operations...

That Ares UAV IIRC was rocket powered, my thoughts were have several(?) that are unpackable and possibly reusable.
For the balloons, I'm having trouble locating my copy of KSR's Red Mars, that'd make things much easier for me...
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
36,879
Reaction score
1,537
Points
203
Location
Langendernbach
Here a small view on the prototype Skycrane, It is still getting some mesh changes and lacks propulsion, but I can already use it for animation and aerodynamic tests.

Between the beams that connect the aerobrake panels to the main vessel will later be textile chutes, that further increase the drag area, and the engines, which will be on tilt-capable pods for thrust vector control.

The inside is still minimal, this will get extended by the fuel tanks, electronics boxes and the payload crane systems. Also there should be some visible actuators and more visible mechanics to extend the panels.

The animation could still get changed a bit...currently the transition from low drag to high drag would result in a drop in drag for a short moment.
 

Attachments

  • Skycrane-inertial.jpg
    Skycrane-inertial.jpg
    36.5 KB · Views: 143
  • Skycrane-Aerobrake.jpg
    Skycrane-Aerobrake.jpg
    63.7 KB · Views: 46
  • Skycrane-full_aerobrake.jpg
    Skycrane-full_aerobrake.jpg
    60.7 KB · Views: 45
  • Skycrane-Prior_liftoff.jpg
    Skycrane-Prior_liftoff.jpg
    63.1 KB · Views: 54
Last edited:

fireballs619

Occam's Taser
Donator
Joined
Nov 4, 2009
Messages
788
Reaction score
4
Points
33
Here a small view on the prototype Skycrane, It is still getting some mesh changes and lacks propulsion, but I can already use it for animation and aerodynamic tests.

Between the beams that connect the aerobrake panels to the main vessel will later be textile chutes, that further increase the drag area, and the engines, which will be on tilt-capable pods for thrust vector control.

The inside is still minimal, this will get extended by the fuel tanks, electronics boxes and the payload crane systems. Also there should be some visible actuators and more visible mechanics to extend the panels.

The animation could still get changed a bit...currently the transition from low drag to high drag would result in a drop in drag for a short moment.

Its looking good. I can finally picture it, so that helps a lot. Do you have an estimate of it's final mass?
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
36,879
Reaction score
1,537
Points
203
Location
Langendernbach
Its looking good. I can finally picture it, so that helps a lot. Do you have an estimate of it's final mass?

Not yet - I make this now for collecting terminal velocity data, this then relates to how much fuel it needs.

Could be about 30-40 metric tons completely fueled without payload.
 

Columbia42

Member
Joined
Dec 4, 2009
Messages
884
Reaction score
0
Points
16
Location
C:\ProgramFiles\Orbiter
A little off topic, here's an idea about the rover:
What if we landed near one of the MER rovers and used it's parts to help us build a small vehicle. It couldn't carry more than one or two people so we would need somethng like a UAV as well but it would save a little mass if we didn't have to bring all of the rover's parts with us.
 

fireballs619

Occam's Taser
Donator
Joined
Nov 4, 2009
Messages
788
Reaction score
4
Points
33
A little off topic, here's an idea about the rover:
What if we landed near one of the MER rovers and used it's parts to help us build a small vehicle. It couldn't carry more than one or two people so we would need somethng like a UAV as well but it would save a little mass if we didn't have to bring all of the rover's parts with us.

I'd prefer to bring all of the parts ourselves. Those parts have been sitting in martian terrain since 2003, so that can't be in mint condition. I think sacrificing a little space is worth it to ensure we will have working rovers.
 
Top