February 1, 2000
The Martian Chronicles (February 2000, experience not real: Simulated in X-Plane only)
NASA has very exact data on the atmospheric pressure, density, and temperature on Mars.
NASA has very exact data on the gravity of Mars.
NASA has rough topographic maps for the entire planet of Mars, and very detailed data for some areas.
The laws of physics, which are programmed into X-Plane, are the exactly the same on Earth as on Mars.
X-Plane needs atmospheric pressure, density, temperature, gravity, and topographic maps to deliver an engineering-accurate flight simulation.
Enter a new level of flight simulation. X-Plane can simulate Mars.
The following is an email sent by Austin Meyer, author of X-Plane, to the X-Plane community, at 4:35 AM, February 24, 2000:
I DID POSSIBLY THE MOST EXCITING THING I HAVE EVER DONE TONIGHT. (OK, technically I finished it THIS MORNING). As some of you may know, I have been gathering data on Martian atmosphere, gravity, surface “texture”, and topography for X-Plane from various NASA sites (http://ltpwww.gsfc.nasa.gov/tharsis/mola.html, for example)
I do NOT yet have the TOPOGRAPHY for Mars, but I DO have everything else, and I have gotten it all entered into X-Plane and designed two planes to fly on Mars as well, and have been experimenting with deign and flight on Mars for the last 6 hours or so. (Could I be the first human to fly a real-time flight simulaton of Mars? I have seen many “movies” of “flying” over Mars terrain, but NONE have been hooked to an actual realistic FLIGHT MODEL… has NASA done a REAL-TIME simulation of Mars flight in a PILOTED aircraft? Has ANYONE?) Well, I have for the last 6 hours, AND IT IS FRIGGIN FASCINATING.
First of all, the atmosphere is ONE PERCENT as thick on Mars as it is on earth… INDICATED airspeed is proportional the the square root of the air density, so the INDICATED airspeed is ONE TENTH the true airspeed.
The result? If you take off with 60 knots on the airspeed indicator, your REAL speed is SIX HUNDRED KNOTS! (about Mach 1) Take it from me, Mach-1 takeoffs are quite a thing to behold, when the plane will barely leave the runway at that speed.
While there is almost no AIR for you, you do have the (sort of) advantage of only about ONE THIRD the GRAVITY, so it is three time easier to get airborne!
Result? A take-off in a well-designed airplane can occurr at a “mere” 400 knots or so, indicating all of 40 knots on the airspeed indicator!
Sound easy? IT ISN’T, BECAUSE WHILE YOUR GRAVITY (WEIGHT) IS ONLY ONE-THIRD OF EARTH’S, YOUR ==>INERTIA<== IS STILL THERE IN FULL FORCE! So you are flying with only 1/3 the total lift of what you are used to having to stay in the air, which seems fine UNTIL IT COMES TIME TO TRY TO TURN OR FLARE!!!!! THEN you see that while the lift for STAYING airborne is only 1/3 of Earth’s, the INERTIA, and thus the lift needed to CHANGE DIRECTION (this includes the landing flare!) IS STILL THERE IN FULL FORCE! The problem is, you DON’T HAVE THAT KIND OF LIFT, SINCE THE AIR IS SO THIN!
Bottom line: All airplanes on Mars are AIRBORNE TITANICS: Ripping blissfully along, unaware of their impending doom due to their inability to TURN against their tremendous inertia.
Landings are impossible without arresting gear. If you can work the flare out right (it IS possible with advance planning) then you will touch down doing about 400 mph. Now how do you stop?
->PARACHUTE? NOPE!!!! 400 mph is only 40 mph worth of drag due to the thin air. You will run off the end of the runway going 100 mph with the chute only “seeing” 10 mph: USELESS for slowing down
->BRAKES? NOPE!!! You only have one-third gravity, so only 1/3 of your weight on the wheels. NO TRACTION!
->Reverse thrust? NOPE!!!! With only 1% atmosphere, jet or prop engines can put out basically no thrust… just barely enough to keep the airplane in flight at mach-0.85.. the jet plane needs a JATO to take off!
So how do you stop? I finally went with ARRESTING GEAR. I know of no other way to avoid blasting off the end of the runway at 200 knots with the chute uselessy deployed and brakes uselessly locked.
Speaking of which, CRASHES are interesting. No air drag to slow the tumbling planes down, and little gravity to drag them to a stop against the ground! Crashes look like “the Agony of Defeat” from the Olympics where the guy on the downhill ski-jump bites it near the top of the ramp and tumbles on and on and on, powerless to stop an accident that started hundreds of yards earlier! (though on mars, at 400 mph, your plane will tumble across the plains for MILES!)
CRUISING ALONG OVER MARS is SPECTACULAR, with the scary red-orange Martian sky, new Martian rocky-red terrain textures, VISIBLY thinner air(!) (due to modified lighting in OpenGL, modified fog in OpenGL, and visibility of stars).. you really can tell you are halfway between air and space! Returning to Earth, you feel like you are flying in soupy water! Yuk!
So what sort of planes can fly on Mars? Not anything from Earth, that’s for sure. Not enough lift or thrust. A Cessna or Boeing will just sit there on the ground without even moving. Put them in the air and they drop like beveled bricks with no wings. Both of my Mars-plane concepts are much like the U-2 Spyplane (designed to operate at around 100,000 ft, in simlar density air) one with a HUGE high-bypass jet engine built AROUND THE FUSELAGE, and another with a smaller rocket engine in the tail, like the X-15. The rocket plane has a lower-thrust engine, with plenty of fuel, for about 30 minutes of flight or so… the JET plane can fly for hours!
My designs are realistic (again, based on the U-2, with reduced weight for the lower structural needs (lower gravity) and modern (composite) materials). The rocket-plane is pretty much gauranteed feasible (known technology across the board) but the jet-powered one I am not sure about since Mars has so little OXYGEN in the atmosphere it may be impossible to keep a turbofan engine running.(My Mars jet-plane has twice the average fuel-consumption, though, to simulate injection of liquid oxygen or nitrous oxide). Bottom line, I now know it IS possible to build and fly a piloted plane on Mars and I now know what it would be like. (though I used a 10,000 ft runway with arresting wires… none of those on Mars now I admit).
AND HERE IS INFO ON TOURING THE MARTIN TERRAIN, ALL OF WHICH IS AVAILABLE WITH X-PLANE NOW:
Thanks to newly-released PLANET-WIDE Mars elevation data from NASA’s Mars Orbiting Laser Altimeter (or MOLA… a satellite orbiting Mars that recently gathered terrain elevation data on the entire planet), we now have planet-wide elevation data for Mars. I have recently gridded all of this scenery for X-Plane, and have been flying over various parts of the planet in the Mars-Planes that come with X-Plane (download X-Plane 6.30 to fly the Mars-Planes on Mars if you have not already).
It is amazing! Is Mars flat, with a few meteor impacts here and there? NOT EVEN CLOSE!
Let me give you some examples: Even though Mars is one half the radius of Earth (one quarter the surface area) it has canyons that make our grand canyon look like a fish-pond (30,000 feet deep!). It has a volcano 65,000 feet tall. The atmosphere is gone to basically pure vaccum at 155,000 feet, so if you climb the volcano you are about halfway to SPACE! Mars has FAR MORE topographic variety than Earth, on a planet with only 1/4 the surface area… so the sight-seeing by air is INTENSE. I have raised the max allowable visibility of X-Plane to 60 miles when on Mars so you can take in the grand vistas.
Taking off and landing is interesting… you are tempted to pick a nice hi-spot to make your airport so you have no obstructions on your landing approach… but the air is so thin up there you can hardly fly! So maybe you want an airport at the bottom of a canyon or meteor crater where the air is thicker? OK, but watch out for the canyon or crater wall as you approach and depart… or impact the crater wall at the speed of sound! (The speed of sound is around the minimum speed needed to fly on Mars).
Below, see the elevation map of of Mars that was generated by plotting all 64,800 ENV files that X-Plane uses for scenery on Mars. While this image was generated from actual X-Plane Mars scenery, that Mars scenery was generated from raw data from the Mars Orbiting Laser Altimeter. Look around and find your favorite place on the planet to fly… low spots provide thicker air, but you must climb out of them to go far!
This is Mars from orbit as seen in X-Plane:
X-Plane has a “demo area” of Mars included (just like Earth) with the rest of the planet available with your X-Plane purchase.