Oz Report

Tin Cup

(This topic is in: <- Apr.28 Apr.25 Apr.24 Apr.23 Apr.22 Apr.21 Apr.18 --> )

Use fishing line, not bricklayer's line (Francisco Grande, Casa Grande, Arizona)

The is the Oz Report.  I make every effort to promote a conversation back and forth between Australia and the US.  There have been a number of benefits from this conversation, with the US competition procedure greatly benefiting.  Changes have also occurred in Australia due to the practices that arose in Florida flight parks.

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Discuss Tin Cup at the Oz Report forum   link»

The Moyes folks after they saw that Andre really won the first day

The cheerleading squad (Francisco Grande, Casa Grande, Arizona)

Vicki Cain <moyes> writes:

What a relief when we heard that OUR Brazilian is charging.  Andre, go you good thing!

Discuss Moyes folks at the Oz Report forum   link»

Weaklinks - the HGFA rules

(This topic is in: Apr.23 Mar.2'05 Mar.1'05 Feb.10'05 --> )

What material should be used for weaklinks? (Hughenden airport, QLD, Australia)

From section 3.4 of the 1999 HGFA Towing Manual:

Recommended breaking load of a weak link is 1g.  - i.e.  the combined weight of pilot, harness and glider (dependant on pilot weight - usually approximately 90 to 100 kg for solo operations; or approximately.  175 kg for tandem operations).

Each pilot should have his/her own weak link of appropriate strength.

It is recommended that a new weak link is used for every launch; or a fabric sheath is used to cover the weak link to protect it as it is dragged along the ground.

Testing weak links tied from "No 8" builders string line has shown that the type of knot used does not greatly affect the breaking strain of the weak link.

I have chosen only the relevant part of the graphic in the manual.  Notice that it uses No.  8 bricklayers twine as the weaklink material.  Here is the requirement from the 2007 Worlds local rules (which I wrote) for weaklinks:

Appropriate aerotow bridles

Competitors must use appropriate aerotow bridles as determined by the Meet Director and Safety Director and their designated officials.  Bridles must include secondary releases (as determined by the Safety Director).  Bridles must be able to be connected to the tow line within two seconds.  The only appropriate bridles can be found here: http://www.ozreport.com/9.039#0 and http://ozreport.com/9.041#2.

Pilots who have not already had their bridles inspected during the practice days must bring their bridles to the mandatory pilot safety briefing and have them reviewed.  Pilots with inappropriate bridles may purchase appropriate bridles from the meet organizer.

Weaklinks

Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers.  All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.

Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line http://www.cortlandline.com/catalog/braid.html and should be placed at one end of a shoulder bridle.  The tow forces on the weaklink will be roughly divided in half by this placement.  Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

For many years a number of us (US pilots) have felt that #8 bricklayers nylon line was not an appropriate material to use for weaklinks as it is not as consistent in its breaking strength (as far as we are concerned) as the Greenspot line used in the US.  At the 2008 Forbes Flatlands Greenspot for the first time was used as the standard weaklink material (thanks in large part to the efforts of Bobby Bailey).  We applaud these efforts to improve the safety of aerotowing by using a better weaklink material.

If the weaklink is at one end of the bridle then there is little to no reason to replace the weaklink after each flight.  The weaklink should be replaced if it shows any signs of wear as its strength may be reduced.  The weaklink is constructed using "fisherman's knots."

A single loop of weaklink is used at the end of the V-bridle or the end of the pro tow bridle.

Pilots at the 2007 Worlds were not actually required to use the bridles pictures above unless their bridle couldn't be hooked up quickly to the carabineer at the end of the tow rope.  They could have a weaklink (four strands) that connected their bridle to the carabineer.  They just had to have the loops of the weaklink available to be hooked to by the ground crew.  This would obviously require a carabineer at the end of the tow rope, and would leave the weaklink attached to the carabineer after the pilot releases, requiring that it be taken off by the ground crew before hooking up to the next pilot.  Of course, a locking carabineer could be used.

It was required that pilots be able to be connected to the tow line quickly both in order to be fair to all pilots and get them in the air in time to compete with each other, as well as to promote safety.  It is safer to have a simple uniform release/bridle system that the ground crew is familiar with and can determine if there is a problem.  The simpler and more uniform the safer, system wide.

Getting pilots into the air quickly is also safer as it reduces the stress that pilots feel on the ground and keeps them focused on their job which is to launch safely and without hassling the ground crew or themselves.  When we look at safety we have to look at the whole system, not just one component of that system.  One pilot may feel that one component is unsafe from his point of view and desire a different approach, but accommodating one pilot can reduce the overall safety of the system.

I look forward to any response from the HGFA or other interested persons.  Again, I have a direct personal and minor financial interest in the issues raised by this discussion, but no financial interest when it comes to weaklink material.

Discuss Weaklinks at the Oz Report forum   link»

1° Alatus Trophy

Three days in May (Levico Terme - Trentino, Italy)

Christian Ciech <<christian>> writes:

We invite you to the "1° Alatus Trophy".  Competition will be held in the City of Levico Terme - Trentino - Italy, from 16 to 18 May 2008.  The enrolment fee is 60 euro (for entrants enrolling by 06 May), or 80 euro after that date.

A maximum of 100 paraglider pilots and 50 hang glider pilots can take part in the competition.

www.vololiberotrentino.it

Discuss Alatus at the Oz Report forum   link»

First impressions of the Wills Wing T2C

The new glider looks great (Francisco Grande, Casa Grande, Arizona)

I opened up the bag and grabbed the battens.  The batten bag was so light.  They felt great.  These are the 12 mm by .045 mm aluminum battens.  They are 20% stiffer and 20% lighter (1 lb weight saving on a T2 with 20% stiffer ribs) than the standard 10 mm aluminum ribs.  The only disappointment was that it was the same old single slot batten bag that made the pilot sort the battens after getting them out of the bag.

Then Rob Kells said that Wills was coming our with a bag that separated the battens, just (exactly) like the Icaro and Moyes bag that we all love.  Great!  An hour later I had one of these bags.  It is black instead of blue, otherwise is is exactly the same.

The next thing I noticed were the beautiful carbon fiber sprogs lined up along the keel all pointing toward the nose.  Airborne crosses their sprogs when they pack it up and the Moyes sprogs point toward the back.  Wills Wing really shows theirs off in the bag.

There are new small black bags at the base of the downtubes to protect the sail.  Lightweight and easy to put on.  The carbon fiber base tube comes with a black slip on bag around it.  Nice.  It would be better if the bag was zippered like Jeff O'Brien's on his Wills Wing T2C 154, as this protects the basetube when it is most likely to be damaged (when it is actually on the glider).

Steve Pearson put little black plastic skids on the base tube which are easily removable.  The idea being set the glider up with these skids attached, then take them off for flying to reduce drag.

Wills has a new pad around the tops of the down tubes and around the keel that you put on for packing.  The design came from Nene Rotor and it is very easy to put on and quite protective.

These are my first impressions and I'll report on my deeper impressions next.

Discuss Wills Wing T2C 144 at the Oz Report forum   link»

Aerotowing at Cloud 9

A tear drop shaped loop (Cloud 9, Iosco, Michigan)

Tracy Tillman Cloud9SA <Cloud9SA> writes:

I have copied/pasted section I(B) from USHPA's aerotowing guidelines below.  Pagen and Bryden provide similar advice in their "Towing Aloft" book.

USHPA AEROTOWING GUIDELINES

These guidelines are established by the USHPA Towing Committee for the sole purpose of enhancing the safety of towing hang gliders aloft with an airborne tug)

I - EQUIPMENT

B - BRIDLES Requirements: 1) Bridle lines should be from 3/16 to 5/16 inches in diameter.  2) Bridles should have no metal parts.

Recommendations: 3) V bridles should be from 6 to 7 feet long.  4) Bridles should be constructed of hollow braid materials so loops can be formed without knots.

Discussion: 1) Thinner lines tend to whip around more during release and can thus entangle the towline.  Thicker lines are harder to cut with a hook knife.  2) Metal parts can injure the pilot upon release and will promote entanglement of the bridle with the towline.  3) Longer V bridles present more of a problem with stowing after release, while shorter bridles increase the forces on the harness and may hamper control.  4) Knots in the bridle promote entanglement with the towline.

We have found best results using 5/16" hollow braid polypro for longer (primary) V-bridle line.  As far as I know, we have never had problems with the thicker bridle line whipping and catching on the tow rope ring.  Thus, that is what we ask our club pilots to use.  Thinner spectra line is ok for short (secondary or pro-tow) bridle line, as short line seems to have less tendency to whip and catch on the tow rope ring, but more tendency to do so if used for a long primary V-bridle line.

For tandems, I will use a 5/16" or 3/8" hollow braid polypro V-bridle line, and we use a round metal ring at the end of the specta tow rope, which is 300 feet long for tandem and first solos.  We have not experienced any problem with the long V-bridle line catching on the ring, because we use the relatively thick bridle line.

However, sometimes visiting pilots will use thin spectra for their long V-bridle line.  To help reduce the chance of the thin spectra catching on our standard 200 foot long spectra tow rope, we use an eyeloop-shaped ring (rather than a round metal ring)--which we have to make, rather than buy.  The eyeloop ring is made from a shaped aluminum tube (batten/rib tube can work) and is lighter and therefore safer than a steel ring--because if the tow rope breaks, the tow rope end ring can snap back and hit the pilot in the face.  (We have not had that happen, but it is another reason for pilots to wear full-face helmets and face shields.)

http://ozreport.com/pub/images/TowlineEnd.pdf

Above is a picture and explanation of how to construct an eyeloop tow rope end, from the "Towing Aloft" book.  We have tried using plastic tube, but it did not work as well as aluminum tube.  We make our tow rope end as shown, with the addition of a single piece of heat shrink tubing shrunk over the open ends of the aluminum tube.

The eyeloop tow end seems to work well to reduce the greater likelihood of thinner spectra bridle line whipping and catching on the tow rope end.  Pilots should be reminded that a weaklink that is too long may whip and catch on any tow rope end, no matter what the shape is (eyeloop, ring, carabiner, etc).  We feel that snap carabiners as tow rope ends may be OK for use at comps for quick launch cycles, because most comp pilots use short pro-tow bridles--but they may not be best for use with long bridles, which tend to whip more.

Discussion and anecdotal information about best practices is helpful, but it would be better for someone to collect and analyze real data, such as by running a reliability/design of experiments study.  A the end of the day, it is all about safety for pilots, and liability and legal defensibility for aerotow operators.  As such, we will continue to follow the published recommendations provided in the USHPA aerotowing guidelines and "Towing Aloft" book, which have worked very well for us here at Cloud 9.

More coming re experimentation.

Discuss Cloud 9 at the Oz Report forum   link»

Santa Cruz Flats Race, day three

We call too long a task again, but six make it to goal (Francisco Grande, Casa Grande, Arizona)

The flex wing results.

The rigid wing results.

The Swift results.

The blogs of pilots here:

http://skyout.blogspot.com/

http://www.goflyxc.com/

The RUC forecast, which hasn't been doing all that well, called for a bit more lift, climbs to 10,000', and light winds.  So the task committee gets excited again and calls a 70 mile triangle, like the first day, but a bit bigger.

The day turned out weaker than forecast and only six flex wing pilots, made it back to goal.  Only two of the rigid wings (and, of course, Brian, on the Swift - commenting when he got to goal, that it was hard and that no flex wing would make it).

Lift was good at first and we got over 6,000' right away.  While at first it looked like we'd start at the first start time, it turned out to be a false start and many pilots went back for the second time.  We were circling just south of the airport (not controlled airspace).

A bunch of us headed off at 1:45 PM east toward the intersection at Valley.  Down to 1,000'I found lift over a dust devil and a bunch of us were there for the ride up.

It was basically easy to get to the first turnpoint (see the results for the task), and then we headed south twenty two miles toward Eds south of Interstate 10.  This is the leg were most (3/5th's) of the pilots went down.

The lift was weak and sporadic.  Pilots were spread out.  We struggled as we headed south.  I was in contact with Jeff Shapiro so we flew together most of the way.

Three quarters of the way south Jeff got low and headed into a powerful looking dust devil having a hard time with it.  I could see the dust devil from a long ways off and when I got there at Jeff's altitude the lift was weak even though the dust devil appeared powerful.

We took off when the bad lift got worse.  Then things really got bad.  A pilot who was with us but lower landed after we went on glide and I was bit over 300' above him working unorganized heat coming off the bare field where he was soon breaking down.

The lift was there, and a bit more than zero, so I stayed with it, ready to land with this unfortunate pilot at any minute.  Jeff was just west of me in weak lift, but I was too low to get to him.

I slowly climbed out of this imminent landing and started looking for better lift as I got over 200' AGL.  I saw a small feed lot just south of the freeway that looked black.  Going over it and searching I found the lift that I had been hoping for and climbed to 7,200'.

Rounding the turnpoint, I was able to catch up with Jeff Shapiro.  Dustin Martin was just over our heads, Chris Zimmerman was nearby and so was Greg Kendall.  Jonny was just a few miles ahead.

The lift was weak and disorganized and while it helped us move along it didn't get us up much.  Jeff was able to get over the nearby hills and landed three miles short of goal.

Andre Wolf also had a few low saves, one down to 500', and went on to win the day, once again.

Discuss Day three SCFR at the Oz Report forum   link»