HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 14, 2014, 12:33 PM
Get your build on!
Aerogance's Avatar
United States, CA, Ventura County
Joined Sep 2008
2,769 Posts
Discussion
Joe Wurts' theories of DS from years ago

I found an old issue of RC Sport Flyer from 2008 that reprinted an much older article by Joe Wurts on Dynamic Soaring. In the article, Joe postulates that in a 60 mph wind a properly built DS plane can achieve 448 mph. This is not too far off from reality!

He goes into some calculations and comes to the conclusion that wing loading "drops out of the equations". Fascinating, because in practice this is normally true! In other words, a light plane can be faster in lower wind because it will turn tighter than a heavy and spend less time losing speed. Of course in super high wind you need more weight and a stronger (aka heavier) structure to fly but that is the exception and not the rule.

Joe then drops the bomb that, like any glider, L/D is king for a DS ship. The current trend with the Kinetic is to maximize L/D through clever airfoil design and very high aspect ratio wings. The results are proven, as the K2M often flies at 12x wind speed and the K130 also pulls up to 12x windspeed. Previously, 10x was the holy grail for dedicated DS ships.

My favorite statement in the article by Joe is "All you have to do is build an airplane that is capable of the air loads imposed on it and have the reflexes to keep up with the responses of the airplane". So true, and planes like the Dynamic and Kinetic certainly keep up with the stresses. Pilots like Spencer and Bruce have the reflexes. It only took 15 years to get there!

The article was written in the very early days of DS and Joe even mentions that flying above 200mph could be catastrophic for the planes of the era. But he makes a very interesting assumption that "you could potentially fly an RC sailplane at about 0.60 Mach!". Not only was this statement absolutely true, but it turns out to be understated by 20%!

I believe the future of high speed DS will depend on flying a 12x + ship in lighter wind (50mph or less) in warm air (warm = lower mach). This will require a low wingloading and high L/D design. Maybe a 200 inch Kinetic will do the trick!
Aerogance is online now Find More Posts by Aerogance
Last edited by Aerogance; Dec 14, 2014 at 04:36 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 16, 2014, 12:46 PM
Mark Robbins
United States, SD, Watertown
Joined Nov 2007
100 Posts
id like to read this if you have a link?
Mark Robbins is online now Find More Posts by Mark Robbins
Reply With Quote
Old Dec 16, 2014, 02:15 PM
Objects in mirror are losing
1000MPH's Avatar
USA, NV, Reno
Joined May 2003
3,640 Posts
This is great!

http://www.charlesriverrc.org/articl...micsoaring.htm
1000MPH is offline Find More Posts by 1000MPH
Reply With Quote
Old Dec 16, 2014, 03:00 PM
Get your build on!
Aerogance's Avatar
United States, CA, Ventura County
Joined Sep 2008
2,769 Posts
Quote:
Originally Posted by Mark Robbins View Post
id like to read this if you have a link?
I cannot find a link or way to view back issues. Here is a thread about this particular issue of the magazine:

http://www.rcgroups.com/forums/showthread.php?t=902181
Aerogance is online now Find More Posts by Aerogance
Reply With Quote
Old Dec 16, 2014, 09:56 PM
Brett
bjaffee's Avatar
So Cal
Joined Apr 2002
5,311 Posts
There's a video interview with Joe where he states pretty much the same thing. I think it might be on one of Paul Naton's "Endless Lift" videos, or perhaps on one of the "Lift Ticket" series. I just remember he's sitting in a lawn chair at Parker.
bjaffee is offline Find More Posts by bjaffee
Reply With Quote
Old Dec 17, 2014, 12:52 AM
Registered User
Carlsbad, CA
Joined Sep 2004
4,699 Posts
Quote:
Originally Posted by bjaffee View Post
There's a video interview with Joe where he states pretty much the same thing. I think it might be on one of Paul Naton's "Endless Lift" videos, or perhaps on one of the "Lift Ticket" series. I just remember he's sitting in a lawn chair at Parker.
lift ticket, great interview and great early DS videos with the progression of speeds.
rockbus is offline Find More Posts by rockbus
RCG Plus Member
Old Dec 17, 2014, 02:49 AM
Marseille: the DS city
France, PACA, Marseille
Joined Aug 2011
14 Posts
Quote:
Originally Posted by rockbus View Post
lift ticket, great interview and great early DS videos with the progression of speeds.
Yes Absolutely a must have.
Available from Reese Productions http://www.reeseproductions.com/
Lift Ticket Director's cut Slope and Dynaming Soaring
Joe Wurts interview at Parker Mountain. the 45 last minutes are all about chasing the DS speed record.

You can also order Lift Ticket to Norway.
R/C road trip with some DS on the most beautiful slopes ever flown.(Lofoten)

Watch it again and again...
French DS guy is offline Find More Posts by French DS guy
Reply With Quote
Old Dec 17, 2014, 02:52 AM
Brett
bjaffee's Avatar
So Cal
Joined Apr 2002
5,311 Posts
Ah yes, you guys are correct, Lift Ticket!
bjaffee is offline Find More Posts by bjaffee
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion New DS Record Idea, Courtesy of Joe Wurts+Pat Bowman ALEX HEWSON Dynamic Soaring 25 Oct 18, 2013 03:35 AM
Video Joe Wurts TIGHT ds laps KingOfTheHill Sailplane Talk 2 May 03, 2006 03:15 AM
Discussion Joe Wurts TIGHT DS Laps KingOfTheHill Dynamic Soaring 6 May 01, 2006 10:39 PM
Joe Wurts Aerobatic DS John Kim Korea 5 Nov 30, 2005 02:19 PM
Joe Wurts Aerobatic DS KingOfTheHill Dynamic Soaring 29 Nov 30, 2005 01:45 PM