June 25, 2015

Know How... 149: Vortex Ring State, Zymbit, and KH250 Build

52 minutes

We talk about a phenomenon that can happen with rotary-wing craft called "A Vortex Ring State", a fast way to integrate your Arduino, Raspberry Pi and Atmel designs, third party DNS, best HD for your old computer, Ruckus ZoneFlex R500, and the KH250 reveled. Helicopter pilots have known about VRS for decades:

While you're flying a rotary wing, there is "up-flow" -- As the wing passes through the air, it pushes air down (creating upwards thrust) while also pulling air UP near the mast and blade grip because those surfaces are not an airfoil.

In directional flight, this isn't a problem because you're moving away from the up-flow.

However, in hover or decent, the up-flow can increase from the mast and blade grip

If the up-flow fully engulfs the rotary wing's lifting surfaces then you lose lift RAPIDLY.

Essentially, the helicopter descends into it's own downwash, losing lift This VRS has been responsible for many accidents with rotary wing craft

The V-22 pilot training has been modified specifically to account for VRS

The Blackhawk that crashed in the Osama Bin Laden raid was lost because of VRS

It's something that EVERY rotary-wing pilot needs to consider. Getting out of VRS is easy, but also tricky

The problem with VRS is that as a craft loses lift, the natural tendency is to increase throttle to regain lift.

But increasing throttle just WORSENS VRS - You just create more turbulent updraft which will increase your rate of decent

This is something that we see with quadcopters all the time.

Hosts: Fr. Robert Ballecer, SJ and Bryan Burnett

Technical Director: Alex Gumpel

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