Date: Tue, 19 Sep 1995 09:27:57 -1000 From: cyuen@rci.rogers.com (Cal Yuen) Message-Id: <43n5jt$p1c@mail.Rogers.Com> Organization: Rogers Communications Subject: Cross-venting a Sputnik Hello, Am considering cross-venting in the Sputnik I'm building next (about 5.5m^2). Has anyone done this and whether this is recommended (Hello Nop?) Regards, Cal Yuen (cyuen@rci.rogers.com) Vancouver BC Canada = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 22 Sep 1995 09:13:00 -1000 From: cyuen@rci.rogers.com Message-Id: <95Sep22.181952edt.20611@janus.rogers.com> Organization: Harvard University Office of Information Technology Subject: Cross-venting a Sputnik Well, this didn't seem to get past my mailserver, so I'll try another way...Cal In article <43n5jt$p1c@mail.Rogers.Com>, you say... > >Hello, > >Am considering cross-venting in the Sputnik I'm building next (about 5.5m^2). >Has anyone done this and whether this is recommended (Hello Nop?) > >Regards, > >Cal Yuen (cyuen@rci.rogers.com) >Vancouver BC Canada > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Tue, 26 Sep 1995 07:23:58 -1000 From: kichiwa@eskimo.com (Mike Eason) Message-Id: Organization: Not Much! Subject: Re: Cross-venting a Sputnik In article <95Sep22.181952edt.20611@janus.rogers.com>, cyuen@rci.rogers.com says... > > >Well, this didn't seem to get past my mailserver, so I'll try another >way...Cal > >In article <43n5jt$p1c@mail.Rogers.Com>, you say... >> >>Hello, >> >>Am considering cross-venting in the Sputnik I'm building next (about >5.5m^2). >>Has anyone done this and whether this is recommended (Hello Nop?) >> >>Regards, >> >>Cal Yuen (cyuen@rci.rogers.com) >>Vancouver BC Canada >> Yes, Cal. I cross vented a 5.2 Sputnik built just before WSIKF this year. All I did was hot cut half circles out of the trailing, truncated rear edge of the risers. By the time the trailing edge is closed, this leaves about quarter (US $.25 coin) sized cross vents right next to the trailing edge. My only comparrison for how well this works is with other 5.2 Sputs built by other people. The small amount of venting seems to noticably decrease any tendency to deflate at the edge of the wind window. I've noticed a wider, flyable window and it can be held stationary right at the edge at any altitude. When doing this, though, always use a down turn to head back. I finally was able to do a trailing edge landing last Sunday at the end of the Whidbey Island Festival and the WSSKC. I can usually do that easily with most peels but it's a little trickier with the Sputs. I don't know how much the cross venting helps here, but I do know that I haven't been able to trailing edge land with other non-vented Sputniks. We should get together sometime with several Sputniks, built with and without venting, and do some actual measurements of the angle of the window edges and performance comparisons. Bridling is the most critical part of building a Sputnik, but it's really not difficult at all. Just a lot of careful measurements. Flattening out the arch of the sail increases the power for buggying but, if overdone, starts to decrease turning ability. Right out of Nop's directions (software, not the book) produce a foil that will turn just inside of it's own wingtips (5.2). I'm making patterns for a 10M^2 now! Watshiwa "more power" kichiwa, -- Mike Eason or Media Specialist: Everett Community College, Everett, WA President: Snohomish County Incredible Flying Individuals, SCI-FI voice:206-334-0362 H. :206-388-9117 W. fax:206-388-9144 3rd Annual Washington State Sport Kite Championships, Sept. 22-24, 1995 Whidbey Island Kite Festival, Ft. Casey Conf. Center, Sept. 22-24, 1995 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 29 Sep 1995 10:50:27 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Re: Cross-venting a Sputnik In article kichiwa@eskimo.com (Mike Eason) writes: >Yes, Cal. I cross vented a 5.2 Sputnik built just before WSIKF this year. >All I did was hot cut half circles out of the trailing, truncated rear >edge of the risers. By the time the trailing edge is closed, this leaves >about quarter (US $.25 coin) sized cross vents right next to the trailing >edge. My only comparrison for how Hmmm... that's interesting. From context, it would seem that your skins reach to somewhere pretty close to the end of the rib. I make my skins over-size, and cut the trailing edge when the rest of the canopy is constructed. It's a pretty inexact science, but I cut the skin as large as I think I can get away with, so that when it is sewn up and inflated, I've got a semi-circular vent between the end of the rib and the trailing edge. Also, since I hot cut the top and bottom skins in one cut, and they tend to stick together, it makes it easier to get that final roll-hem just right. Andrew -- New to rec.kites? START HERE! | To: www@kfs.org send an email message like this->| Subject: service /-\ () >< () |\/| () >< () /-\ | http://www.kfs.org/kites/welcome/index.html 80+ chrs/line looks messy on many screens. Often too messy to bother reading. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Wed, 4 Oct 1995 05:38:37 -1000 From: kichiwa@eskimo.com (Mike Eason) Message-Id: Organization: Not Much! Subject: Re: Cross-venting a Sputnik In article , andrew@tug.com says... > >In article kichiwa@eskimo. >com (Mike Eason) writes: >>Yes, Cal. I cross vented a 5.2 Sputnik built just > before WSIKF this year. >>All I did was hot cut half circles out of the tra >iling, truncated rear >>edge of the risers. By the time the trailing edge > is closed, this leaves >>about quarter (US $.25 coin) sized cross vents ri >ght next to the trailing >>edge. My only comparrison for how > >Hmmm... that's interesting. From context, it woul >d seem that your skins >reach to somewhere pretty close to the end of the >rib. I make my skins >over-size, and cut the trailing edge when the rest > of the canopy is >constructed. It's a pretty inexact science, but I > cut the skin as large >as I think I can get away with, so that when it is > sewn up and inflated, >I've got a semi-circular vent between the end of t >he rib and the trailing >edge. > >Also, since I hot cut the top and bottom skins in >one cut, and they tend >to stick together, it makes it easier to get that >final roll-hem just >right. > >Andrew >-- >New to rec.kites? START HERE! | To: www@kfs.org >send an email message like this->| Subject: servic >e >/-\ () >< () |\/| () >< () /-\ | http://www.kfs. >org/kites/welcome/index.html >80+ chrs/line looks messy on many screens. Often >too messy to bother reading. Well, that's the way I'm doing the next one, oversize skins. On the 5.2 I built the upper and lower skins exactly to size, which works but leaves no room for error. I had just enough at the trailing edge to make the hem. The same amount of cross venting could have been accomplished though, as you say, by simply closing the trailing edge further rearward, past the end of the profile riser. Has anyone experimented with a thicker profile in this same design? What would a thickness of, say, 180f the chord do? ...maybe also increasing the intake opening slightly? Also, I have been wondering what would happen if a peel type lift increasing "bump" were added to the top of the trailing edge. I have a reference book of NCAA standard airfoil profiles (about 1500 and variations) that shows a similar "bump" added for increased low speed lift, near stall conditions, added to standard profiles like the Clark xxx and the Gottingham 298. ??? Watshiwa "more power" kichiwa! -- Mike Eason or Media Specialist: Everett Community College, Everett, WA President: Snohomish County Incredible Flying Individuals, SCI-FI voice:206-334-0362 H. :206-388-9117 W. fax:206-388-9144 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =