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

a reply to: smurfy
So they got about 1 inch of lift and about 20 something seconds of air time, even in a vacuum chamber.

I guess it will work, but it could be better and may as well make one of those little mechanical hopping frog robots with a camera attached to it. Hopping across Mars, one inch and 20 seconds at a time. You could amost make a robot snail at that rate.

Ah just messing.

I dont know what people are bitching about. I call that progress, even though, long ways from the whole going to mars thing.

a reply to: Phage

Alright, I'm doing the math on this and it seems pretty plausible. Is the 1.5kg weight including the motor weight? I'd be shocked if so, but if it is then this is entirely possible.

4 ft propellers at a 4 inch pitch, spinning at 2900 rpms gives you nearly 200 pounds of thrust. So 2 of those would easily lift this thing. On earth, at ground level the drone weight is the equivalent of 100 pounds. So 200 pounds of thrust x2 would lift this thing with no problem.

EDIT: Just saw the video, didn't realize they were doing a single motor design with only two blades. That drops their thrust down to 117 pounds. Yeah this thing will struggle on mars. It will work, but it will be a slow ascent.

a reply to: Dfairlite

You're doing the math? That's pretty awesome, because there's a lot to consider. Laminar separation, velocity differential between tip and root. And you have to fly the thing so changing angles of attack have to be considered. Tip stalls would be bad.



But yeah, it'll work.
If it doesn't break.

a reply to: Phage

I'm not doing the math on maneuvering it, I'm doing the math on getting it off the ground. And not even really "it" just anything of this size and weight. No need to worry about laminar separation or velocity differentials.

a reply to: Dfairlite

No need to worry about laminar separation or velocity differentials.

How can you calculate lift without considering velocity differentials? The tips have a much greater velocity than the roots.

a reply to: Dfairlite

I think your number for the chopper is off a little.

Chopper

weight will be 1.7kg

It should have the lift to fly NP as you say.

a reply to: Phage

Because they don't adversely affect my conclusions. If anything, they'll help.

a reply to: Dfairlite

Because they don't adversely affect my conclusions.

Sounds like confirmation bias to me.

So you're using a constant spanwise lift distribution.
What blade planform and camber are you using? What is the thickness of the foil? Is it undercambered?

a reply to: 1947boomer

The composition of the atmosphere does matter. That even matters on earth.

Even in small things like a bit of extra weight and the thin air around mountains. Its why one can fly over, and the other crashed when it took on an extra pound or so at the wrong time of the day, then it should have.

Rotatory metal wirly birds, may not be the way to go on Mars. But we shall see...I guess.

Look at how happy they are to fly over, well not really over, but close and to take off at those altitudes off Mt Everest.

That thin earthly atmosphere.

a reply to: galadofwarthethird

It's all about the Reynolds number.
A man sized airplane or rotorcraft on Mars will be a problem.

I don't think the problem is not going to be the lift. The problem is going to be control and not crashing it.

a reply to: LookingAtMars

I was going on 1.5kg and adjusted the weight to mars equivalents on earth.

Trying to lift 1.5kg on mars is like lifting 0.57kg on earth (adjusting for gravity). Using the atmosphere on mars (0.006 of earth's) to lift it makes it about 95kg.

But if it's 1.7kg the number we need to lift is 107.6kg (235lb). So two props each capable of ~120lbs of thrust can lift it, kind of. About like seen in the video.

a reply to: LookingAtMars

Control is part of the calcs.

But it has to be autonomous. A 10-40 minute delay is unacceptable for remote controlled flight.

a reply to: Dfairlite

I was going on 1.5kg and adjusted the weight to mars equivalents on earth.

Ok, now I see, thanks. The problem is it will have to fly by computer because of the time lag a person will not be able to control it. NASA has experience controlling the rover by computer program, so it may work out. If it does it will be very cool.

a reply to: LookingAtMars

Yes. That will be quite a task. As phage pointed out, actually maneuvering the thing is going to drop your thrust considerably and with a thrust to weight ratio of 1.02:1 there's not room for that.

Of course, they've optimized this and considered other factors that I haven't. So maybe they got an extra 10 or 20% out of it. They're the rocket scientists, not me. I'm just a random curious person on the internet.

a reply to: Dfairlite

They're the rocket scientists, not me.

No.
A whole other thing.
They're aerodynamic engineers.

a reply to: Phage

It was a joke... hopefully yours was too.

a reply to: Dfairlite

Always

a reply to: Phage

I figured, but I've seen a lot of missed jokes on these types of forums... so you never know.

originally posted by: Dfairlite
a reply to: LookingAtMars

Yes. That will be quite a task. As phage pointed out, actually maneuvering the thing is going to drop your thrust considerably and with a thrust to weight ratio of 1.02:1 there's not room for that.

Of course, they've optimized this and considered other factors that I haven't. So maybe they got an extra 10 or 20% out of it. They're the rocket scientists, not me. I'm just a random curious person on the internet.

Just fly it straight up and let the wind blow it.

That may be what they do for the first flight.