Open Class

I have been away from soaring for 12 years and have noticed the open class now has long wing and much shorter wing birds (JS-1C) competing. I am curious how do the 21 and 23 meter new ships keep up with the ASW-22BL's and Nimbus-4's. Are the new shorter wing gliders better overall (better L/D, better penetration ) or just better on strong days when wing loading counts more than the ability to stay in the air?

On Friday, February 13, 2015 at 7:29:03 PM UTC-5, Jonathan St. Cloud wrote:
I have been away from soaring for 12 years and have noticed the open class now has long wing and much shorter wing birds (JS-1C) competing. I am curious how do the 21 and 23 meter new ships keep up with the ASW-22BL's and Nimbus-4's. Are the new shorter wing gliders better overall (better L/D, better penetration ) or just better on strong days when wing loading counts more than the ability to stay in the air?

I think a lot depends on where you"re flying. Strong conditions may favor higher wing loading, weaker prefers lighter wing loading/higher aspect ratio..

On Friday, February 13, 2015 at 8:11:29 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
On Friday, February 13, 2015 at 7:29:03 PM UTC-5, Jonathan St. Cloud wrote:
I have been away from soaring for 12 years and have noticed the open class now has long wing and much shorter wing birds (JS-1C) competing. I am curious how do the 21 and 23 meter new ships keep up with the ASW-22BL's and Nimbus-4's. Are the new shorter wing gliders better overall (better L/D, better penetration ) or just better on strong days when wing loading counts more than the ability to stay in the air?

I think a lot depends on where you"re flying. Strong conditions may favor higher wing loading, weaker prefers lighter wing loading/higher aspect ratio.

the JS-1C seems to have done pretty well and run with "the big boys" at both Uvalde 2012 and Leszno 2014.

http://soaringspot.com/wgc20112/resu...ay-by-day.html

http://soaringspot.com/leszno2014/re...ay-by-day.html

On Friday, February 13, 2015 at 6:42:17 PM UTC-8, Tony wrote:
On Friday, February 13, 2015 at 8:11:29 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
On Friday, February 13, 2015 at 7:29:03 PM UTC-5, Jonathan St. Cloud wrote:
I have been away from soaring for 12 years and have noticed the open class now has long wing and much shorter wing birds (JS-1C) competing. I am curious how do the 21 and 23 meter new ships keep up with the ASW-22BL's and Nimbus-4's. Are the new shorter wing gliders better overall (better L/D, better penetration ) or just better on strong days when wing loading counts more than the ability to stay in the air?

I think a lot depends on where you"re flying. Strong conditions may favor higher wing loading, weaker prefers lighter wing loading/higher aspect ratio.

the JS-1C seems to have done pretty well and run with "the big boys" at both Uvalde 2012 and Leszno 2014.

http://soaringspot.com/wgc20112/resu...ay-by-day.html

http://soaringspot.com/leszno2014/re...ay-by-day.html

My (limited) understanding is that span loading is a significant factor. If you can make a lighter glider with a high aspect ratio, the span can be reduced as the weight is reduced without sacrificing un-ballasted performance. With a smaller wing area the wing loading can be increased without busting the overall weight limit for the class.

I know of at least one pilot that has passed on the Quintus or EB-29 to go with the JS-1c. As a Nimbus3 driver I can't help but be envious of the lighter empty weight, shorter span, better handling that comes with better performance to boot.

Cheers,
Craig 7Q

The smaller the wing (area, not span), the bigger the relative drag of the fuselage becomes.

On that note, what happened to the 18 meter Diana II that was rumored to come out?

On Saturday, February 14, 2015 at 1:57:36 PM UTC-6, J. Nieuwenhuize wrote:
The smaller the wing (area, not span), the bigger the relative drag of the fuselage becomes.

On that note, what happened to the 18 meter Diana II that was rumored to come out?

Maybe the same thing that happened when someone asked Greg Cole (Duckhawk designer) if he was going to make an 18 meter version. He said "Why would you want to make it slower?" :-)

On Saturday, February 14, 2015 at 1:29:03 PM UTC+13, Jonathan St. Cloud wrote:
I have been away from soaring for 12 years and have noticed the open
class now has long wing and much shorter wing birds (JS-1C) competing.
I am curious how do the 21 and 23 meter new ships keep up with the
ASW-22BL's and Nimbus-4's. Are the new shorter wing gliders better
overall (better L/D, better penetration )

If you look at the polars, those old long wing gliders have amazing glide angles at 55 knots, but they lose badly to the new thin airfoils at high speed.


or just better on strong days when wing loading counts more than the
ability to stay in the air?

Yes, exactly, where "strong days" means anything over 1 or 1.5 knot climbs.

On Friday, February 13, 2015 at 9:49:02 PM UTC-8, Bruce Hoult wrote:

...but they lose badly to the new thin airfoils at high speed...

It's kind of a nitpick, but there's really nothing new about thin airfoils. What has changed in the last decade and a half is the cost-effectiveness of the structure required to implement them in competitive sailplanes.

Thanks, Bob K.

On Friday, February 20, 2015 at 10:09:07 PM UTC-6, Bob Kuykendall wrote:
On Friday, February 13, 2015 at 9:49:02 PM UTC-8, Bruce Hoult wrote:

...but they lose badly to the new thin airfoils at high speed...

It's kind of a nitpick, but there's really nothing new about thin airfoils. What has changed in the last decade and a half is the cost-effectiveness of the structure required to implement them in competitive sailplanes.

Thanks, Bob K.

I think there is something new about the thin airfoils in use today, though, Bob. Laminar flow over a greater percentage of chord. Laminar flow over that chord at much lower reynolds numbers. Ability to maintain low drag to higher C/L.

Chicken and egg sort of question. Did structural design philosophy dictate airfoil design in terms of thickness, or did the airfoil design encourage continued use of the same old structural design techniques?

Steve Leonard

On Saturday, February 21, 2015 at 5:09:07 PM UTC+13, Bob Kuykendall wrote:
On Friday, February 13, 2015 at 9:49:02 PM UTC-8, Bruce Hoult wrote:

...but they lose badly to the new thin airfoils at high speed...

It's kind of a nitpick, but there's really nothing new about thin airfoils. What has changed in the last decade and a half is the cost-effectiveness of the structure required to implement them in competitive sailplanes.

Sure, carbon spars enabled them.