Nasa lies about Mars atmosphere.Helicopter to fly in Mars" 0.6Percent of earths atmosphere"

a reply to: LookingAtMars

No, it isn't.

The physics of helicopter flight are well understood, and have been for 3/4 of a century.

originally posted by: Bicent
Meh considering, we really don’t understand how a helicopter can fly, who knows.

At least that is what I was taught. Was never excited about the helicopter ride I took in a Blackhawk once, knowing I was flying in a machine we did not really understand how it was doing it.

I would imagine the blades will have to go faster maybe I dunno to fly.

I think when you say "we" don't understand you actually mean you don't understand.

a reply to: SpaceBoyOnEarth

Nasa drone


A drone

So rotors are 1.2 m on Nasa drone that weighs 1.76kg (1760g)

Argos drone width is 18.3 cm which makes the rotors about 5 cm ish.

Helicopter lift is generated by gas molecules passing over and under the blades NOT through.

Now look at the width of the blades. Argos drone 1 or 2 cm, NASA drone 10cm at least.

Rotor speed; Argos 9k (went to manufacturer site forums) Nasa 2.8 k.

Crunching all the maths tells me that NASA drone easily produces more than 64 times lift of Argos.

originally posted by: carewemust

originally posted by: SpaceBoyOnEarth
a reply to: carewemust

Thats what im trying to tell you.

The 0.6 is a lie.

I wonder if it has to be AIR that blows sand around on Mars? Is there any other element that can do this?

It's aliens.

During my 35+ years as a NASA aerospace engineer I actually worked on several different Mars airplane and helicopter designs. I see that people here are asking all the same questions I’ve heard a hundred times, so maybe I can answer all of them in one post.

First, the Martian atmosphere: The first successful Mars landers were the Viking missions in 1976. Since that time, NASA has landed the Pathfinder mission, the MER mission, the Polar Lander mission, and the MSL mission. All of those missions carried miniaturized weather station instruments (pressure, temperature, wind speed). Because of those in situ measurements, we have a pretty good atmospheric model for Mars (as far as density and pressure are concerned). One important difference between Mars and Earth is the fact that the atmospheric density on Mars changes by about plus and minus 15% every Mars year, because during Winter at the Martian south pole, a large amount of CO2 freezes out and falls to the ground as dry ice snow. During southern Summer, it turns back to gas and builds up the atmosphere density again. That means that If you’re designing anything that depends on the air density to operate (entry vehicles, parachutes, airplanes, helicopters) the performance of the thing you’re designing very much depends on the time of Martian year that you arrive.

The Martian atmosphere model that NASA uses is called MARSGRAM and it can be downloaded from the internet by anyone who wants to use it. It is used in the preliminary design of all NASA Mars missions to figure out where on Mars you can land, and with how much weight.

Another important factor in Mars mission designs is the location on Mars where you intend to land. The Southern hemisphere terrain is quite a bit higher than the average level (referred to as the “zero datum” altitude) and the Northern hemisphere is lower than the zero datum. Since the air density increases the lower in altitude you go, it is much easier to land Mars missions in the Northern hemisphere and that’s why all Mars landers so far have been targeted to land there. The Mars 2020 mission that will carry the little helicopter is targeted to land in the Northern hemisphere at the Jezero crater at an altitude about 2.5 kilometers below the zero datum shortly after the Northern Spring equinox. At that particular time and place, the Martian atmospheric density will be about 1/50, or 2% of the Earth’s atmospheric density at sea level. If you were at a higher elevation and a different time of the year, the air density on Mars might be only 1% of Earth’s sea level. That’s why you can’t use just a single number for air density when thinking about Mars flight.

Notice that I have been talking about atmospheric density. That’s because the combination of air density and airspeed is what keeps airplanes and helicopters flying. The composition of the atmosphere doesn’t really matter very much. To be more exact, it is a quantity called dynamic pressure (often abbreviated as “q”) that creates lift and drag on a wing, a rotor, or an airframe. Mathematically, q is equal to one half the air density multiplied by the airspeed squared. What that means is that—for a given aircraft—if the air density is lower, you have to fly faster to generate the same amount of lift. But on Mars, where the gravity is only about .38 as much as it is on Earth, you don’t have to generate as much lift.

It might be helpful to consider a hypothetical example:
Suppose you had a 1975 Cessna 172 flying along at 2500 ft MSL on Earth. According to my operator’s manual that aircraft would weigh about 1225 kg (2700 lb) and would require about 57 kW (76 hp) to cruise at around 49 m/s (109 mph). If you could instantaneously transport that Cessna to Mars, it would only weigh about 465 kg (1025 lb) because of the lower gravity, but because of the lower atmospheric density, it would still have to fly about 4.65 times faster than it would on Earth, or about 228 m/s (510 mph). Because it would have to fly faster, it would also take about 77% more power to fly on Mars—about 100 kW (134 hp). Of course, on Mars, because there is no Oxygen in the air, the power would have to be provided by an electric motor or stored propellant.

Exactly the same principles apply to the operation of a helicopter rotor; a rotor is considered a “rotary wing”. At the time and location the Mars mini-helicopter will operate, its rotors will have to turn about 4.65 times faster than they would on Earth and will consume about 77% more power. I assume that’s why they couldn’t use standard RC helicopter motors, and had to make special motors to turn faster and consume more power.

Notice, that the requirement to fly a wing or to turn a rotor faster only works up to a certain point. The speed of sound on Mars is about 244 m/s (546 mph), so that hypothetical Martian Cessna 172 would be flying around .93 Mach in order to generate enough lift. A C-172 wing couldn’t get close to .93 Mach without shock waves forming all over it. For that reason, it is usually necessary to design a subsonic Mars airplane wing or Mars rotor with more surface area than an equivalent Earth vehicle so that it doesn’t have to operate close to its Mach limit. The best way to do that is usually to make the wing or rotor longer, since that will also improve the L/D ratio. That’s why most Mars airplanes tend to look more like a U-2 than a C-172.

One final point: it is often argued that since the highest a helicopter on Earth can fly is about 40,000 ft (with no payload) how could one possibly fly in the thin air of Mars (which is equivalent to about 100,000 ft on Earth)? The answer is that a Mars helicopter only has to fly at the 100,000 ft equivalent altitude (plus or minus a little) but in order for an Earth helicopter to fly at 100,000 ft, it has to first climb up to that altitude from sea level. That means its rotor has to be able to deliver an amount of lift that’s greater than the weight of the vehicle at every condition between zero and 100,000 ft. It is perfectly possible to design a helicopter that could fly on Earth at 100,000 ft (if anyone needed one) but it is not clear that a rotor that could do that could also climb up to that altitude. On Mars, it doesn’t have to climb to that density altitude—it is delivered there by a spacecraft.

a reply to: SpaceBoyOnEarth

originally posted by: oldcarpy

originally posted by: Bicent
Meh considering, we really don’t understand how a helicopter can fly, who knows.

At least that is what I was taught. Was never excited about the helicopter ride I took in a Blackhawk once, knowing I was flying in a machine we did not really understand how it was doing it.

I would imagine the blades will have to go faster maybe I dunno to fly.

I think when you say "we" don't understand you actually mean you don't understand.

I don’t want to sound like a dick and I left myself open for that shot. But please in your best explanation tell us HOW it flies and WHY. The WHY is important. Not BECAUSE but WHY.

I’ll wait.

a reply to: Bicent

Simple answer, the rotors act as an airfoil similar to a wing. Instead of forward motion generating lift, the rotors turn, generating their lift. You change the angle of the rotor to adjust the lift generated and change the direction of flight. When the rotors generate enough lift to overcome the weight the helicopter takes off.

a reply to: Zaphod58

Aircraft, sure, but the helicopter altitude record is 40k feet.

a reply to: Dfairlite

Keep reading.

a reply to: Zaphod58

So why don't we tilt our blades to achieve this maximum lift capability?

a reply to: Zaphod58

I read two more pages, you never addressed this.

a reply to: Dfairlite

Rotor blades do tilt and change angles.

a reply to: Zaphod58

So if we can't make up for the thinner atmosphere with tilt, then we have to make up for it in rpm's or blade surface area, right?

a reply to: Dfairlite

Well gee, I didn't realize I was the only one posting in this thread. As pointed out, the Mars scout isn't having to lift itself all the way to that altitude like it would here on earth. A helicopter on earth starts at sea level and would have to climb to 100,000 feet. That means it would have to be optimized to generate lift at all altitudes. The Mars helicopter is starting at the equivalent of 100,000 feet and is flying at that equivalent altitude. It's optimized for that altitude.

a reply to: Dfairlite

The Mars helicopter is spinning at 2900 rpm with a four foot rotor, for a craft that weighs the equivalent of 1.5 pounds. That is actually quite a bit of lift.

a reply to: Zaphod58

So if we took this thing up to 100k feet here, and turned it on, you'd expect it to be able to hold altitude?

a reply to: Bicent

Not BECAUSE but WHY.

They are designed to do so.

originally posted by: Dfairlite
a reply to: Zaphod58

So if we took this thing up to 100k feet here, and turned it on, you'd expect it to be able to hold altitude?

Yes.
And that's exactly what happens in the chamber.

a reply to: SpaceBoyOnEarth

Well if you divide bull by #, then you times that to second power of nothing, then you square it by a square. Eventually you get a whole lot of words and numbers which equal a whole lot of conjectures. And then those conjectures will be institutionalized in the form of mass

Ever wonder how they know the atomic and geological structure of all these planets, when they never been there and the best telescopes are vague at best, some are just dots, or fly by composite images that were put together by a computer model.

Its called theoretical science. As in, its a theory, or as they say an educated guess. Lets just say, NASA or any other corp or entity like the gov will have a hard time raising and building a structure here on earth, and it will likely be delays, and cost 10 times as much or projected, take 20 times as long, and well not to mention all the palms that need greasing, and the hardhats on the ground, the unions, and raises, and the architects that project numbers, which exist only on a graph, and so on, and so on.

Ya! Mars brah! Its only going to be on the screens for a long while yet to come. Same as the moon. Who are you to question maths and the accepted composition of the atmosphere of Mars. Just enjoy the ride.

As for igniting a space race to mars?

I think as things stand now, there is a higher chance that all the people waiting to go to mars, may die of the bubonic plague in the next 70 years then there is of going to mars.

a reply to: galadofwarthethird

Its called theoretical science

It's called engineering.

Something a few seem to have missed. Something called the Reynolds number. It sort of has to do with the viscosity of air in relation to the object. It's one reason bumblebees can fly. This is real aerodynamics, not like the math presented in the OP.

The low density of the Martian atmosphere and the relatively small Mars Helicopter rotor result in very low chord-based Reynolds number flows, 𝑅𝑒#=𝑂(103−104). At low Reynolds numbers,flat and cambered plates can outperform conventional airfoils,making them of interest for the Mars Helicopter rotor.

rotorcraft.arc.nasa.gov...

A rotorcraft engineered for Mars will fly quite well, on Mars.

You cannot compare a tiny helicopter to a man sized helicopter. I used to make little tiny gliders out of rolling papers. It's all about the Reynolds.