Incredible Drone Turbulence (now *that's* some propwash!)

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NASA's Supercomputers Reveal the Incredible Turbulence Produced By a Drone

"If you’ve ever been blasted by the downwash of a drone when it flies over you, you know how much air four spinning rotors can move. But to help improve the design and flight characteristics of future drones, NASA had its supercomputers simulate what that air movement actually looks like, and it’s impossibly complex."

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Very cool. I was amazed at how much prop wash the P4P creates --- much more than I was expecting. A lot louder than I was expecting as well. o_O
 
In terms of understanding the basic airflow dynamics, I doubt that matters much at all.
 
tip interactions are actually very important and can greatly effect the performance of an aircraft.
That slapping sound you can sometimes here comes from tip interactions amoungst other things.
 
tip interactions are actually very important and can greatly effect the performance of an aircraft.
That slapping sound you can sometimes here comes from tip interactions amoungst other things.
Not arguing your point. Just saying that in terms of what they were trying to demonstrate (the incredibly complex airflow) it's completely irrelevant. If the purpose of the simulation was to analyze prop efficiency, it would be critical.

Or are you saying that because they didn't include this particular state of prop positioning in their simulation, what we're seeing is completely invalid?

Maybe you get my point now...
 
to be honest their simulation is so impossible that maybe it is slightly irrelevant.
it wouldn't have taken much to spin each motor at a different speed.
 
to be honest their simulation is so impossible that maybe it is slightly irrelevant.
it wouldn't have taken much to spin each motor at a different speed.
Have you done any simulations like this? Written code to do stepwise FEA to simulate a system like this?

I have.

So, we'll just have to agree to disagree, I guess. However, based on my direct experience with such flow models, I'll say this: IN MY OPINION, had the modelers included parameters to vary prop speed in this simulation, so that tips occasionally met, the animation you see in the OP would look exactly the same. YOU would not be able to tell us which one was the original above, and which had the varying prop speeds, if the only thing you were able to see was the calculated airflow (i.e. the AC with its props was removed from the picture).

So, I'll say again: You point is completely irrelevant to modeling the airflow and looking at how complex or how simple it is. The complexity of this airflow has to do with the fact that there are multiple props more than anything else, interfering with each other in terms of orderly, directional airflow.

Go right ahead and continue to think this would look radically different if only the tips met now and then in the simulation. Ignorance is bliss, I suppose :D
 
it doesn't matter if i could tell the difference, the fact is the difference would exist.
I have drones that by extending each arm 2cm to reduce tip interaction massively change the flight performance of the aircraft (on fixed wing and multirotor platforms).

changing the airfoil angle on a car by 1 degree may look visually to be no different but be huge when crunching numbers.
 
it doesn't matter if i could tell the difference, the fact is the difference would exist.
I have drones that by extending each arm 2cm to reduce tip interaction massively change the flight performance of the aircraft (on fixed wing and multirotor platforms).

changing the airfoil angle on a car by 1 degree may look visually to be no different but be huge when crunching numbers.
My last response on this idiotic debate.

Again, you are right, but you're engaging in this sort of discussion: What color is the sky? You answer: Seven.

This simulation was not about analyzing the efficiency of propeller designs. It was about modeling the general characteristics of airflow under a quad drone. So, since you have now acknowledged that you couldn't tell this difference regarding the complex appearance of the airflow with the changes to the simulation, my work is done.

Feel free to continue to argue with no one about that which is not in dispute: Yes there would be a difference. No, you would not be able to see it simply by looking at the incredibly complex, chaotic pattern of the airflow.

So we would come to exactly the same conclusion that NASA set out to show with this simulation: The airflow under a quad copter is incredibly complex, the point of the OP.
 
"NASA had its supercomputers simulate what that air movement actually looks like, and it’s impossibly complex"
Except it isn't what it actually looks like... hence being irrelevant to its stated purpose, but thats being pedantic which is why i didn't say its pointless or useless, I was just pointing this little observation out, you are the grump who threw a tantrum and went overboard buddy...
 
:cool: Have a nice year, and stay out of the prop wash
propwash.jpg
 

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problem with the simulation is all 4 motors spin at different speeds so the tips sometimes meet which they never do in this simulation
Please post your qualifications in such matters.
Laughable at how the experts here are so quick to disregard the findings of one of the most respected brain-trusts in the field of aeronautics.
 
:cool: Have a nice year, and stay out of the prop wash
View attachment 73369
Just to explain what we're seeing here, because it isn't totally obvious: That plane got blasted by propwash from another plane from the left side, pushing it into the propeller of another aircraft, which then sliced up the fuselage as spin and walked down the side.

I can imagine how helpless the pilot felt as the plane was being pushed sideways, and there was nothing he could do with any of his controls to stop it. Dude was probably on Prozac for a year after that episode.
 

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