# Vortex Ring State (Helicopter)

We know about the Osama Bin Laden raid in Pakistan; a previously-unknown stealth helicopter crashed in the compound, caused by a helicopter phenomenon known as "vortex ring state" [http://en.wikipedia.org/wiki/Vortexringstate] when the rotors are close to the ground. Any ideas/suggestions/TOTALLY INSANE methods to overcome this?

Note by Kevin Techa
5 years, 7 months ago

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold
- bulleted- list
• bulleted
• list
1. numbered2. list
1. numbered
2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1paragraph 2

paragraph 1

paragraph 2

[example link](https://brilliant.org)example link
> This is a quote
This is a quote
    # I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
MathAppears as
Remember to wrap math in $$...$$ or $...$ to ensure proper formatting.
2 \times 3 $$2 \times 3$$
2^{34} $$2^{34}$$
a_{i-1} $$a_{i-1}$$
\frac{2}{3} $$\frac{2}{3}$$
\sqrt{2} $$\sqrt{2}$$
\sum_{i=1}^3 $$\sum_{i=1}^3$$
\sin \theta $$\sin \theta$$
\boxed{123} $$\boxed{123}$$

Sort by:

Can you explain this to me please?????

- 5 years, 7 months ago

Hmmm.... well, the helicopter rotor works like an aircraft wing, except it is rotating at high speed. The wing-like airfoil generates lift. However, when the helicopter gets close to the ground and is hovering, the downwash (air pushed down to the ground by rotors) causes a "turbulence", flows back up and starts to fluctuate the lift. Eventually the lift got "killed" off, the helicopter stalls and crashes to the ground. Quickly moving the helicopter away works, but if it is close to obstructions it would be suicide. I want to know if there are other ways to solve this. sorry for not being clear anyways...

- 5 years, 7 months ago

if it is moving in a circular manner then th lift would be successful

- 4 years, 5 months ago

Here's an idea:land the helicopter somewhere else :D

- 5 years, 7 months ago

-__- The same could occur, but yeah moving to "clean air" does work. still, it could crash into buildings, so I want to know other solutions

- 5 years, 7 months ago

Maybe you could put some big "wings" under the rotor,with moving panels to deflect the downwash forward/backward/straight up.

- 5 years, 7 months ago