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 StanFoster 04-14-2012 04:57 AM

Root vortices

1 Attachment(s)

 All_In 04-14-2012 07:39 AM

Hi Buddy!!!
Thank you for posting this the drawing helps. Having not experience with it I'm struggling to really understand it. This helps!!!

 Rotor Rooter 04-14-2012 09:06 AM

Stan you are bring up an interesting topic; particularly as to how it might apply to a gyrocopter.

The idea of placing a solid disk in between the roots of the blades to stop the fountainhead effect has been an intriguing one. On a helicopter the front of the rotor disk must be tipped downward during forward flight.

However, on the gyrocopter it will be tilted back and the disk can act as a small lifting body.

Perhaps it has never been considered for the gyrocopter because it might create a slight resistance to pitch change, due to its inertia and aerodynamics.

It is a little, very little, likeVranek's idea.

Vranek Disk Rotor Helicopter concept - YouTube

Dave

 kolibri282 04-14-2012 09:30 PM

Dave and Stan,

interesting thoughts! Perhaps the effect of a root disk wouldn't be very noticeable for its lift effect but the losses (vortices) at the root would be diminished. Would be very interesting to see if the effect could be measured. Uhmmm... Dave... didn't you talk about a laboratory van once ...???... After all ..... if you can't measure things you can't tell if you are making progress....;-)

Cheers,

Juergen

 jebthereb 04-14-2012 09:54 PM

how to react?

Stan as you know i have one whole entire hour as a student helicopter pilot.

How do you correct/react to this situation to resolve this.

Do you increase altitude or just move out of it and find a different place to hover?

You talk about clock positions. Is this in relation to the wind direction?

 Rotor Rooter 04-14-2012 10:10 PM

Quote:
 ..... if you can't measure things you can't tell if you are making progress....;-)
Juergen,

That's the advantage of working on helicopters instead of gyrocopters. If the idea does not work, then in a helicopter you can always back up and take another run at it. ;)

Dave

 birdy 04-15-2012 01:57 AM

Usually there is enough wind that the root vortice isn't picking up much debris,
Stan, just wundern, [ slightly off track] , at wot wind speed can you land/TO without feeln translation?
Light choppys like your dont have a very powerfull wash compared to sumthn like a R44, so a strong wind will have you landn before any translation occurs.

 StanFoster 04-15-2012 04:09 AM

Jeb- I just watch for recirculating debris, and move out of the hover if its excessive. Most of my hovering is over grass, and its not much of a problem. I won't hover over sand or gravel as this is just too rough on the blades and turbine. The fields have been extra dry lately and I won't hover and create a dust storm, but instead just keep moving along fast enough to keep from recirculating the debris. .........................Birdy- You can take off in winds around 20 mph or greater and be above the speed that produces the shudder the rotor feels when its running into its tip vortices. Stan

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