The Oz Report
Volume 6, Number 60
7 PM, Friday, March 22nd, 2002
"Toto, I have a feeling we're not in Kansas anymore."
- In this issue:
Chelan – the real story (part 1) How about other demo days here in Florida? Please subscribe I've got just one word - Nylon They just can't see us Hang Gliding Spectacular Canugra Classic – that's in Queensland, Australia, this fall Aerodynamics 101 Held on Satellite Image of the Day Strap on the weights
Chelan – the real story (part 1)
(This topic is in: <-- Jul.12 Mar.24 Mar.23 Mar.22 4.131 4.130 4.129 --> )
This is the first of a series of articles about Chelan Butte, site of the next Women's, Class 2, and Class 5 Worlds. The point of the articles is to give the readers an idea of what to expect at the Worlds if they are going to go flying there. Readers who are contemplating flying in the Chelan Cross Country Classic will also find material of interest here.
First of all a few web sites:
http://www.cloudbase.org/cbcc2000/default.htm Click ‘Jul' to get the dates for the Chelan XC Classic and the Worlds.
http://www.cloudbase.org/ChelanWorlds/ The home site for the Worlds in Chelan. You'll find rhe rules, where to stay, turnpoints, maps, etc.
http://www.cloudbase.org/CBCC2000/Articles/ArticleMain.asp?id=99 How to win in Chelan (at the Classic). There are various other articles on flying in Chelan in this general area.
The FAI/CIVL calendars for the events: http://events.fai.org/hgpg/details.asp?id=1324 (Class II Worlds), http://events.fai.org/hgpg/details.asp?id=1100 (Women's Worlds), http://events.fai.org/hgpg/civl-calendar.asp
I have written a great deal about Chelan Butte and the Chelan Cross Country Classic in the past and readers can check out OzReport.com/Ozv4n118.htm for example, and there are many other examples. Go to OzReport.com/index00.html and click on any reference to Chelan in the Table of Contents issues 113 through 131.
Today I'm going to start off with some facts about geography. Chelan Butte is a 3835 foot (3,700' at launch) hill at the southeast end of Chelan Lake, a 50 mile long glacier cut lake whose greatest depth is about 1,500'. The Butte rises 2,700' above the lake and 3,100' above the Columbia River to its east.
The Butte is just to the east of a large north south mountain range – the Cascades. It is the end of an east west spur coming off the Cascades. ChelanLake comes out of the Cascades to the west and stops just north of the Butte just before it would have run into the Columbia River.
While the Butte is the end of a spur, it pretty much stands by itself with its flanks facing south, east and north. Bob Franklin has created a three dimensional view of the Butte and the area around it:
The red lines are hang gliding routes from the Butte across the Columbia River to the east and southeast. We will discuss these more later.
The north northwest flank of the Butte faces ChelanLake . There is a steep launch (“Lakeside”) from this side that we do occasionally use if there is a northwest wind down the lake (rare) or there are thermals coming up this side (not as rare). While the lake is quite cold because it is glacier fed from the North Cascades, there is plenty of hill side in between the launch at the top of the Butte and the lake, so the air can heat up.
The launches that are used for competitions are on the lower south end of the Butte so we won't be launching to the north. The east launch, known at “Ants in the Pants” is a good early launch into a southeast facing bowl. It faces the also quite cold Columbia River and early in the day the east sides of the Butte may not be warm enough to produce enough buoyant air to keep you up.
The south launch, used when the sun has heated up the southern side of the Butte , is the “Between the Rocks” launch. It's flat so a strong constantly accelerating run is required. You need to continue flying with some speed until you get out past the two rock outcroppings and over the edge of the Butte .
There is a much unloved southwest facing launch – “the Green Monster.” The top part of it is shallow and pilots have been known to launch twice there. This launch is used when the winds are blowing strong up the Columbia River (common) and its use portents that it will be very difficult to get up and leave the Butte in a thermal.
The big picture is that the Butte is a moderately sized hill almost surrounded by water, cold water. Thermals are produced when air is warmed by the sunlit flanks of the Butte .
Our goal is to get up at the Butte and head east over to the flats east of the Columbia River. The height of the eastern rim of the Columbia is about 2,900' or about 800' below the launch at the Butte. The gorge of the Columbia River is quite wide and deep and we are required to get across the gorge before we can begin flying our tasks.
In order to cross the Columbia Gorge it is important that we get high enough to make it onto the flats with enough altitude to find the first thermal on the flats. Sometimes we won't be able to do that and we will be required to find some lift on the east flanks of the gorge.
As you can imagine it is difficult to find any lift over a cold river, although sometimes it happens that there will be lift coming off the sides of the Butte that will carry you some or even much of the way across the gorge. How far do you have to fly to get across the gorge before you can get up over the flats on the eastern side? About four miles.
Here is a view from overhead of the two main routes from the Butte over to the flats: one going east toward Mansfield and the other going southeast toward Lamoine.
When gliding over a river gorge for four miles you are most likely to find yourself in sinking air. You will want to get to the other side of the river as soon as possible. The other side rises from the river, but it doesn't do so instantly. You have to fly quite a ways past the river before you get away from the river and over the thermal producing areas.
In the next Chelan article I will look more closely at getting up at the Butte and crossing the river.
How about other demo days here in Florida?
Wills Wing is having their big party here at Wallaby Ranch this April 4-7th. What's with the rest of the hang glider manufacturers out there? Don't they want to show off their wares also? How about some demo days around this time over at Quest Air. Then pilots could come down and check out Wills Wing and also the other great gliders.
GW wants me to go look at an intermediate flex wing glider that he's got over at Quest, and I'm sure that there are plenty of other wings that need to be seen after the show in Garmish this weekend (my reporter is there and will be on the job).
Wouldn't many of my readers come down to Florida for three or four days of glider demos? Cheap tickets to and cheap motels in the Orlando area.
Do I really have to tell you how to sell gliders? J
Please subscribe
(This topic is in: Jun.6'03 Mar.22 )
If you are looking at the Oz Report on-line please think about subscribing because it costs me to have you view my web site, but it doesn't cost me to have you subscribe to the Oz Report.
Usage on the Oz Report web site jumped dramatically this month from 6,500 hits a day to 14,000. Oz Reports and other reports downloaded in the last three weeks went from 85 Mbytes/day to 175 Mbytes/day. Over 4 gigabytes of Oz Reports went out from the web site in March – so far, not including the daily subscriptions.
Now I know that a lot of this is my fault as I've been creating rather large Oz Reports over the last month. Still anything you can do to help would be great. We'll see how it goes over the next few months, and see if I have to step up to a higher level of service from my web host provider.
Thanks for all the wonderful support!
I've got just one word - Nylon
Well a number of you took me to task about Bob Hannah's suggestion regarding alternatives to Nylon.
Mark Stucky <stucky_mark> writes:
Vectran is amazing stuff. We used a 1000ft length of 3/4" Vectran for the tow rope when I was towed in the F-106 behind a C-141. It doesn't have much elongation under load (you want some shock absorption and this was the argument against using steel cable for hang straps) but I figure the long nylon webbing of the harness would probably absorb enough.
Michael Zupanc <zupy> writes:
Maybe this is confusing wording. The "normal material" just states the material that is commonly used in most existing hang straps. 8mm rope has 50mm2 cross section. Trying to keep exotic materials and metal connections (because of the lack of "give" and the resulting shock loads) out of the picture for the "main."
Bill Belcourt <bill> points to the article that I've put up on my web site at: www.davisstraub.com/Glide/2000_international_technical_res.htm. The conclusion of this report (on materials used for climbing) is:
The decrease in strength with use is a worry for any of the Technora, Kevlar or Vectran materials. The Gemini and the Spectra-A are also extremely stiff, difficult to tie and untie, and an 18 foot piece makes a bulky object hanging from the harness. They make excellent chock cord (where a stiff cord is desirable), but would make a poor cordelette. We think that Titan is a suitable material for this application. The webolette is an elegant solution to multi-point anchors and also good, although we'd prefer to see slightly higher strength on the single-strand arms. Last, nylon cord and webbing is cheap, strong, universally available, and seems to have virtually unlimited flex life.
Angelo Crapanzano <angelo> writes:
Well, I often don't agree or understand CIVL rules too but, in this case, there is a reason to use Nylon. Its elasticity is around 4 to 8 times more than Vectran, Spectra or Kevlar. A hangstrap must mainly absorb shock loads and elasticity (i.e. elongation) is mandatory. The shock load depends a lot on the elasticity. If the elasticity was "zero" then the smallest shock load would bring the load to "infinite." Also because of its elasticity, Nylon is, generally speaking, more resistant to fatigue (repetitive shock loads) than more rigid fibres.
At the beginning of hang gliding started the fashion to use 4 or 5 mm steel cables but, after a few accidents it was discovered that, under a shock load, they where breaking easier than a Nylon rope which was nominally less strong.
The test was made in a very crude but perfect way. A harness was loaded with about the weight of a normal pilot then suspended from a very rigid point. The harness was lifted about one meter and let fall. The steel cable broke like nothing while the Nylon webbing did not.
The experience tells us there is also a reason for a back-up rope: several years ago a friend of mine, to adjust the hang point on his brand new glider routed the original hang strap in an unusual way: the webbing was cut in flight after half an hour and he was lucky he had borrow one bad looking strap just before taking off.
I agree that on rigid wings the hang strap is so short that its actual elasticity may look not so important, but elasticity counts quite a lot on knots too. Nylon loses over 40% of his strength in a knot while Kevlar loses 70%. A similar problem comes with stitching. If the webbing is reasonably elastic, the load would spread on more stitches while if it's too rigid the load would be on few stitches which will break one after the other (and if the material is stronger, at equal strength there is less room for stitches too).
Please note the elasticity is needed on the harness main strap too, where it's even more important because it's longer (this is yet another requirement to think about when designing a rigid hang strap).
Safety is important and where is the problem if, in competition, all of us has the same drag due to hang straps and cables?
They just can't see us
Several readers also objected to Arnold's note on radar reflectors. Mark Stucky <stucky_mark> writes:
A radar reflector on a hang glider or paraglider wouldn't do much good for air-to-air detection. Civilian aircraft are only armed with weather radars and an augmented hang glider could possibly be seen at a few miles as a blip on the scope but nobody would give it a second thought. In fact, airborne weather radar manuals specifically say not to attempt to use them for air-to-air detection and collision avoidance.
Modern military fighters use pulse doppler radars which suppress ground clutter and also filter out slow speed traffic. Typically anything slower than 60kts will be invisible. The exception to this is the F-18 which has a 20kt threshold for a specific non-scanning air combat mode (which requires a visual on the target to use). I tested this mode myself on hang glider targets of opportunity in the OwensValley in the early '90s.
A ground FAA radar could possibly be helped by the addition of a radar reflector.
If it makes you feel better to hide a reflector in your double surface then go for it. You may want to stick a lucky rabbit foot in you harness pocket also!
Mark G. Forbes <mgforbes> writes:
As I recall from a thread on this a couple years ago, the problem with radar reflectors is that civilian aircraft don't carry an air search radar. They have transponders, which squawk back when interrogated by air traffic control systems, but no air-to-air sensing. The only aircraft that DO have such radars are military interceptors, and the reason for their use is to provide targeting data to the weapons. I know there are some collision avoidance systems now, but I think they rely on communication of altitude, heading and speed between the aircraft to determine whether evasive action is needed.
Ground-based radars filter slow-moving objects out to avoid clutter, and we don't fly fast enough to get over their threshold. Seems like the only reason to have a reflector is so that you can be seen by the one kind of airplane you'd rather not have notice you. We would however be much safer from impacts with large ships. :-)
http://www.caasd.org/proj/tcas/
http://www.af.mil/news/Dec1996/n19961224_961316.html
http://www.eos.tuwien.ac.at/Oeko/RSchild/Rules/id83.htm
http://www.smartregs.com/data/sf91221.htm
http://www.archangel.com/cds.htm
http://www.gtwn.net/~keith.peshak/taillight.htm (opinionated, but interesting)
http://www.army-technology.com/projects/patriot/
http://www.airtoairmissiles.net/aim7.htm
http://www.airtoairmissiles.net/amraam.htm
http://www.canit.se/~griffon/aviation/text/missiles/aam.html
http://www.jstars.robins.af.mil/History/Definition.htm
http://www.milparade.com/1999/35/061.htm
http://www.nawcwpns.navy.mil/hybrid/rbti.html
http://www.nycedo.com/edocorp/page18.htm
http://www-cmpo.mit.edu/Radar_Lab/FAQ.html
http://www.ussailing.org/safety/Studies/usnaradarenhancer.htm
Hang Gliding Spectacular
Douglas Haber writes:
Nags Head North Carolina May 17 - 20, 2002
The 30th Annual Hang Gliding Spectacular and Air Games at Jockey's Ridge State Park, Nags Head & Currituck County Airport, Maple North Carolina is just around the corner. Watch as past winners Doug Haber and Ken Brown (Moyes America) duke it out again as this downtube bustin' dune skimmin' pylon turnin' high flarin' spot landin' event unfolds!
The competition begins May 17th on the sand dunes of Jockey's Ridge. There will be competitions for advanced and novice pilots. Other features of this years Spectacular are glider demos, aerotow competition, Woody Jones memorial street dance ( BIG PARTY), awards ceremonies and usually a film festival. Don't forget to bring you best edited Hang gliding bloopers on VHS. And as always, the annual inductions to the Rogallo Hall of Fame will occur Sunday which should not be missed.
This event usually turns into a four day non stop party and Reunion where old friends get together and live it up! Hang Glider Pilots with a Hang One or higher are welcome to compete. Prizes are always great and this is definitely set up for spectators. Sharing gliders usually works fine. Bring your Sun tan lotion! BE THERE! (The hard-core pilots usually start to roll into town on Thursday the 16th for a Pre-Spectacular party that evening. BYOB)
Call to Register. 1-252-441-2426 ask for Bruce Weaver. Also go to http://kittyhawk.com for details.
Past competitors and instructor list http://www.kittyhawk.com/events/instructorslist.cfm
Canugra Classic – that's in Queensland, Australia, this fall
(This topic is in: <-- Sep.28'04 Sep.26'04 Aug.28 Mar.22 4.140 -> )
Roderick Stead <canungrahg> writes:
St Bernards Canungra Classic 2002 CIVL Cat 2
Sat 28-September- Sat 5 October 2002
Canungra, QLD. Registration Friday 27th, Entry fee $120 ($150 if paid after 31st August) + $40 site fees GPS mandatory, intermediate with inland experience. Cheques/ money order to Rod Stead, 9 Grifffth Street North Tamborine 4272. This year you can pay by Visa/EFTPOS, ring Vicki at St Bernards, they are kindly letting us use their payment facilities. Entry inquiries to Rod on 0428 132215, 07 55450969 or <canungrahg>.To register visit www.triptera.com.au/canungra and follow the links.
Last years great accommodation and meal deals available, call Vicki on 07 55451177 to book and obtain prices,visit their website at www.stbernardshotel.com.au.
Aerodynamics 101
richard miller <richardmiller> writes:
Why? - to get back to the issue of the non-recognition of the upstream propagation. What reason for this? The shadow that intuition casts over any understanding of the mechanics of the bending of a stalk in the wind, or the fluttering of a leaf, is long and deep.
Half of all dynamic interactions in a free atmosphere are of a positive nature, involve positive dynamic pressure; the other half, their complement, are negative. Against this is the total intuitive disposition of the mind, intent on understanding, to see and to interpret the whole in positive terms, in terms of contact and impact. Classical aerodynamic theory from its origins in the Principia to the most recent article or book is testament to this.
This derives from our nature, or what we intuit our nature to be from our identification with the mass, motion, movement, momentum of a human body, and of the role that contact/impact play in the course of our lives. Everything we accomplish in life, with the minor exception of sucking beer through a straw, involves the manipulation of mass or the transmission of momentum by contact of some sort.
We are so deeply in the thrall of the intuition of contact/impact as to be far beyond any consciousness of it, which is exactly the definition of intuition. We are in the thrall of a congeries of intuitions that direct and misdirect our lives including the most insidious of all that we act, and think, as free, unfettered agents.
Held on
Steve Rathbun <srathbun> sends me the scanned in version of Charlie Baughman's article on his system for keeping himself off the sail:
Charlie asked me to scan the article from Dec 97 HG and send it to you. The first two images are the entire article and the last two are just the photos.
http://www.xmission.com/~srathbun/CBINV.JPG http://www.xmission.com/~srathbun/CBINV2.JPG http://www.xmission.com/~srathbun/CBINV3.JPG http://www.xmission.com/~srathbun/CBINV4.JPG
Satellite Image of the Day
Dennis Eckert <deckert7> writes that you can get a different satellite image each day from NOAA at http://www.osei.noaa.gov/.
Strap on the weights
Tex <texdoc> writes:
I too am familiar with the Straps G.W mentions regarding weightlifting and the possible application for us as mentioned. The beauty of those straps if used correctly is that they do not require and 'extra tightening of you grip' for them to work. The strap should wrap at least once around the bar and so when pulled it tightens on itself.
Simply sew a loop into the end of your chosen tape (big enough to thread it back through it self) as per the standard weight lifting wrist straps, or just buy a pair of those. THEN add the hook at the loop, reinforced as required and place an eyelet in the other free end of the strap (lengthened to suit the wrap around the bar as required).
Simple! Perhaps you could find some tape etc that is elasticised that does not suffer any diminished strength to use.
Hope this gives you some further developmental ideas. Question is have you done enough chin ups to be able to pull your chest back to the bar <g> Me, I will just hope to avoid those dragons in the air and trust the factory settings and sprogs on my Climax at this stage.
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