Ventus 3

New pic on the SH site. First flight very soon.

What is the advantage of a polyhedral(?) wing?

On Thursday, December 24, 2015 at 12:57:38 PM UTC-8, Clay wrote:
What is the advantage of a polyhedral(?) wing?

Never being mistaken for a PW-5?

On Thursday, December 24, 2015 at 3:57:38 PM UTC-5, Clay wrote:
What is the advantage of a polyhedral(?) wing?

One benefit of the greater dihedral outboard is that it has a longer moment to apply stablizing force which increases roll stability and roll response to yaw.
It also spreads the the flow field giving the effect of more span than a "flat" wing.
It allows the tip skids or wheels to be further inboard so the tips don't see ground loads.
It also looks cool.
UH

One aerodynamicist explained that it is a benefit in climb but has a penalty in cruise. It does look cool though. Word on the street it is a three year wait for a new Ventus

So you have 65 ft of wing in a 60 ft span (I'm exaggerating). Glider thinks it has 65 ft span. Runway lights must like it too. Not sure my 5'1" wife would.

On Thursday, December 24, 2015 at 1:49:12 PM UTC-8, wrote:
SNIP
It allows the tip skids or wheels to be further inboard so the tips don't see ground loads.

It also puts a lot of wing very close to the ground on roll out. Closer than some rocks, weeds, etc. From experience owning a Duo.

Looks really cool.
Handles very nicely in the air.
More ground clearance with wings level.
(you may need to ask the wing runner to hold it higher)
With a low sun angle, there's always a reflection catching your attention.
Doesn't fit in the trailer as easily.
Pulling the tip out of the trailer, you're not on the center of gravity.
If there's any undulations or rocks, with a wing down the wing can hit outboard of the skid.
Not much to compare to a PW-5, unless V3 has a forward-hinged canopy.
Are the multiple angles easy to refinish?
Jim

On Thu, 24 Dec 2015 13:56:24 -0800, Jonathan St. Cloud wrote:

One aerodynamicist explained that it is a benefit in climb but has a
penalty in cruise. It does look cool though. Word on the street it is a
three year wait for a new Ventus

Curiosity: why did he say that there's a benefit on the climb but penalty
during the cruise?

I've been told that using a multi-panel wing is better because the drag
from a dihedral break increases sharply as the angle increases: so much
so that a six panel wing performs better than a four panel wing of the
same span and area because of reduced drag from dihedral breaks. I don't
remember any speed effect being mentioned, hence my question.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Thursday, 24 December 2015 17:26:24 UTC, wrote:
New pic on the SH site. First flight very soon.

Looks quite similar to the Arcus wing. The Arcus glides well at speed, although the wing loading cannot be particularly high.