The Oz Report

The Airborne Gulgong XC Classic – day 2

(This topic is in: <- Nov.23 Nov.21 Nov.20 Nov.19 Nov.18 Nov.17 -> )

Partials results from the first day:

1Steve Moyes Moyes Lightspeed
2Ricky Duncan Airborne Climax C2 14 - 6 seconds behind
3Davis Straub Airborne Climax C2 14
4Rohan Holtkamp Airborne Climax C2 14

24 others.

I would love to publish the full results, but I don't get e-mail with the results as the scores are done at the glider port, which I don't believe has a phone, as it doesn't really have power.

Today was another light wind day with scattered cu's forming at 10,000' at 11 AM.  There were a few cu's in the neighborhood, but for the most part they will be somewhere else.  We will get a few high ice clouds over the airfield.

Rohan and the task committee called a hundred and eight kilometer triangle task to the north and west.  We do love coming back to the glider port and putting our hang gliders in the hangar.  Thanks to Ian the owner of the air field.

Even though the start window opens at 12:30, I've asked Ricky and Rohan when they are taking the start window (2 or 2:30), so I'll wait to get off at 1:30.  There are 28 pilots and 2 trikes, so it does take a while to get us in the air, but no one is pushing and it seems to be just fine.

I hit strong lift at 300 feet while on tow and pin off at 500' when I get high on the trike.  I come back to the lift, but after climbing out a couple of hundred feet, I lose it and get back down to 300' before I find it again and then climb out to 8,000' AGL.  Ground level here is 1,500'.

Unfortunately I don't get the high again in the start circle, take the start time 4 times, and finally leave with 5,400' AGL at 2:40 PM.  Ricky Duncan is with me, just behind and over me.  Rohan will wait for the 2:50 PM clock, and Steve Moyes will get the 2:30 PM one.

We've noticed the strong sink and now Ricky and I will hit it big time on the way to the first turnpoint at 800 fpm down.  Down to 2,500' AGL I will work my way into the little foot hills and find something that turns into over 500 fpm to 8,000' AGL.  Ricky will miss that and have to go a lot further to get up.

The lift is strong and so is the sink out on the course, but there is plenty of lift to find.  Over the course it will average over 500 fpm, with some sustained 900 fpm up high.

There is a crowd at the first turnpoint as I pass Ricky digging his way out of the hole he flew into.  It looks like we are catching up with the earlier pilots although we are still below them.

It feels like a headwind going to the second turnpoint and while there are clouds around, none are on the course line.  Steve is out ahead and getting low about 15 kilometers from the second turnpoint (it is a 30 kilometer leg).  This will slow him down.

After getting high where Steve originally got low, we dive into the second turnpoint to again find a crowd in layers over the turnpoint climbing.  Steve comes in under me and we find 600 fpm to plenty high.  He heads out and I can only follow, not keep up with him.

Now there is a cloud just to the left of the course line to goal and we head for it.  Another crowd and 600+ fpm to where we get more than high enough to go on final glider 30 kilometers out.  Almost all the faster pilots will come in within about a fifteen minute span.

We are using a virtual goal with a goal cylinder of 400 meters.  Given that we've come back to the glider port every day, it is no problem knowing where the goal is.

I don't have any results from today yet.  Rohan started 10 minutes after me and beat me to goal by 5 minutes.  Other folks did well also.

Flying the Airborne Climax C2 14

(This topic is in: <- Nov.21 Nov.20 Nov.19 )

The towing seems to be fine.  I can follow the trike and not get knocked around too much even when going through a strong thermal.  I am having a bit of trouble keeping the glider down with the trike, so I'm getting off early.  But, overall it does seem pretty easy to tow.

I'm getting better at thermaling.  I didn't experience any time where it felt like the glider just wanted to keep rolling (unlike yesterday).  It feels like the glider favors right hand turns, so I preferred left hand ones, and was in fact able to climb better when turning left.

I'm feeling a bit beat up tonight with soreness in the shoulders.  It does take a bit more work to fly a flex wing, and in my case this is doubly true because I still am not able to control the yaw.  I just can't get it to fly straight.

I feel that my control inputs are just out of synch with the glider as I can see other pilots flying it straight.  This is really inefficient and I just can't keep up with Ricky or Steve on glide.

The pitch pressures feel solid and it is nice to have the bar come back when you pull on the VG.  I'm getting use to the VG and pulled it on a lot more today.  I also let it completely off in most thermals.

I averaged about 65 km/h when gliding and 40 km/h overall on the course.  I did fly for 6 minutes at over 75 km/h.  I do have a hard time controlling the glider at the higher speeds.

I feel real comfortable with the glider.  It doesn't make me think that its going to tuck at any minute.  The closest I'm come to disaster was on the first day thermaling under Steve and Ricky and getting pretty sideways while turning right.  Today I concentrated on moving my whole body up and away from the lower wing.

I have to high side it when doing a right turn and a little bit in a left turn.  Usually this comes about because the thermals are not consistent and smooth.  Later in the day at high elevations with smooth big and powerful thermals, I didn't have to do much.

Had a good landing in no wind conditions with the VG all the way off.  It seems pretty easy and mellow to land.  The control frame is huge, really huge.  Topless flex wing gliders have come a long ways over the last five years.

Felix in America

(This topic is in: Nov.19 Nov.17 )

Vince Endter <n4nv> sends this to the rigid wing list:

Felix Ruehle was at Mission Soaring yesterday to give a talk on the aerodynamics, construction and flying of the Atos line of hang gliders, and his new tail design.  For the engineering types, he went quite in depth about the aeronautical design of the Atos.  With Felix's permission, I am going to make a web page that will cover most of the repair and checks needed to keep an Atos flying safely for many years.

There are a couple of points that I will make now.  The 50mph/80Kph VNE is the VNE of the Atos with full flaps.  The Atos is truck tested by the DHV to 62mph/100Kph.  80Kph is the same as the yellow arc in an airplane.  It should be only exceeded in smooth air.  Felix considers 75mph/120Kph to be the VNE of the glider.  He cautions that at this speed, it is possible for turbulence to cause the glider to exceed design loads.  The same can be said to a too aggressive push out at this speed.

Felix told us of an older gentleman who showed up one day to test fly an Atos.  He was about 60 years old and was dressed in a suit.  He appeared to be a little frail.  Felix waited later in the day for conditions to die down before letting the pilot test fly the glider.  He as a little concerned with his launching because it looked like he was a little weak to ground handle the glider.

The fellow had a good launch in flew away.  When they arrived at the LZ, he heard stories from the other pilots that this guy did 4 LOOPS in the Atos.  It never occurred to Felix that he should tell this guy not to do aero in the Atos, since it looked like he would have enough work just to fly the glider.

The tail Felix has designed moves the neutral point of lift further away from the CG, which improves stability.  Unfortunately, we were not able to view the video of the DHV test of the tail due to Felix's tape being in PAL (European) format.  The tail does provide lift in flight and the pilot might want to move their hang point back 1 cm to make up for this.  He also recommends placing the glider bag in the D- cell to offset the weight of the tail.

I was able to test fly his new tail.  I flew my old Atos (Christoph and I put on a new D-cell).  I was surprised that the bar still seemed to respond with the same light touch that I am used to.  I thought with a fixed tail (especially one that generated lift in flight) would make the bar feel heavy.

It was a normal day at Sled Heaven so I was not able to tell how much the tail dampens the bar in rough air.  I did not notice anything different on landing, but Felix says he can feel the tail stall just before he flares.  I did some stall entries in flight with the tail and found that I had to push out farther to get the glider to stall.  I did not pay attention to my airspeed at the time so I don't know it the tail lowers the stall speed, but it felt like it.

Felix reiterated what I have said in the past about speeds to fly the Atos.  Don't fly by watching an airspeed indicator.  Fly by bar position.  The glider should be trimmed so that the base tube is just below your nose.  In rougher air pull the bar in a couple of inches.  The closer one hangs to the base tube, the more stable the glider.  In Europe where rigids can surpass flex wings in number, the pilots having the most trouble transitioning to the Atos are high time pilots who have been flying 25+ years.  They have a hard time not pushing out while flying.  There should be very little need to push out more than your forehead in flight.

I was supposed to be flying today but the winds are out of the northeast so I wrote up more from Felix's talk as well as my private conversations with him and Christoph.

One of the reasons Felix came to the US this trip, was to apologize to his dealers about the lack of parts and service from AIR.  At the height of production (just before Davis' incident slowed the market), sales of the Atos had reached 12 a week.  Soon after the Davis incident the market dropped to two a week.  Now that AIR is slower, Felix is trying to get on top of the parts and service situation.  While in Northern California he is going to train the people at Mission Soaring how to do a check on an Atos.

In Germany, gliders are required to be certified every two years (similar to aircraft annuals here).  During this inspection, all the cables are replaced, new flap and spoiler limiter ropes, some of the mounting hardware replaced.  The sails are removed and the spars are inspected.  The sails are re-installed and the ribs are checked for proper washout.

Christoph arrived here a couple of days earlier than Felix.  He came over my house and I installed one of my 15 minute racks (made from electrical conduit) on his rental car and then we installed a new spar on my old Atos.  The new spar was for a C model, so I guess I might have and Atos C-.  We performed most of the checks done in Germany.  All the ribs were checked and the number 8 was found to be about 2 degrees out of spec.  Chris showed me how to change the angle; it only takes about 5 minutes.

I will have pictures of this when I make the web page along with the spec for each rib.  I will also show pictures of the wing sweep check.  I found out the proper way to remove and replace the sail.  It should take only about a minute to remove and 2 minutes to replace.

Even though the Atos is massed produced, it is very much a hand made glider.  All the composite work is done with wet lay-up by hand.  The spars are made as one piece in a mold, and then cut in half.  This helps insure that both spars are the same weight.  The spars are made with a foam core, as is the d-cell.  Two layers of carbon with a 45° weave are used at the inner spar and one layer with the same weave is used at the outer spar.

The attachment bolts have carbon roving wrapped around them and then extending down the spar.  There are 90 at the inner spar tapering to 15 near the tip (I always wondered how they attached those big steel eyebolts to the carbon spar).  The spars are made in the same fashion as several European sailplanes.  Composite parts are no longer made in Germany (except for prototypes at the AIR factory), they are produced in the Czech Republic and Slovenia to keep the cost down.  Felix had no secrets of the design or manufacturing of the glider.

At the AIR factory they will change an Atos to an Atos-C for $1950 euro.  I hope that they will train the dealers here how to do the same change.  The washout is a little different on the C than the original Atos, less at the inner ribs and more at the outer ones.  All the Atos gliders can have the new washout specs.

Some more notes on stability.  If too much stability is designed into a glider bad things can happen as well.  Too much bar pressure can result and when the nose is popped up this is bad.  In Europe this year, a pilot flying a beginner king posted flex wing with lots of stability tumbled when the pilot's nose was popped up and he did not have enough strength to pull it down.  The result was a vertical climb to a stall, then tumble.

Tailless gliders are a compromise in stability.  During spin testing, AIR and the DHV found that the Atos would not spin more than one and one half turns (this was without the tail) even though the pilot continued with the control input that caused the spin in the first place.  The way it spins it self corrects after that.  There have been some accidents in Europe as a result of aerobatics.  In one case, the pilot fell against the control bar and it broke, then the broken piece punctured the spar, which caused it to fail.  There were three Atos tucks in Europe (over a 3 year period) where the glider recovered and the glider flew away undamaged (though there was probably some staining to the pilots harness).

Felix has been working on a version of the Atos where the pilot sits up in the wing.  AIR started on the project in 1999.  Now that production has slowed down, they might get more time to work on it.

The tails are still considered pre production.  The design is finished, but they are still working on the manufacturing and mounting.  Currently they are making 4 tails a week.  As soon as they feel confident of the process they will increase to 8 tails a week.

Many of the pilots in Europe don't want the tail.  Some say the tail makes the glider feel more like a flex wing (is this a good thing?).  Without the tail, Felix recommends 0 to 5 degrees of flap when thermaling.  With the tail he recommends 5 to 15 degrees.  The German comp pilots who fly with the tail are able to fly with less twist in the wing.  The drawback to this is you can never safely fly the glider without the tail without changing the twist to its pre-tail spec.

Richard Nikoley <rn> responds to the rigid wing list:

Having been there, there's one thing I'd like to mention and that is I really appreciated the attitude of Felix.  He's the consummate scientist, just like talking to Steve Morris.  He's not going to stand there and bullshit you about what the tail does or does not do.  He said flat out that the tail likely will not prevent all tucks, and he doesn't even know if it will prevent any that would have occurred tailless.  He also said that a lot of pilots in Germany have commented that they couldn't tell any difference.

So far, all they are confident in is that it provides a smoother ride in choppy air -- i.e., so you're bar is not hunting all over the place -- and that using the same control inputs that cause a spin without the tail, causes a slight wing-over with the tail.  When I brought up the video clip we all saw a couple of weeks ago, he was quick to correct me by saying that the video with the tail was _not_ a spin, but was a test using the exact same control input as what put the ATOS in a spin without the tail.

Zapata World Records on TV

David Glover <david> writes:

http://www.reevolution.tv/episodes.php?thisEpisode=11

Showed November 16 and again on November 22 on TNN.  Look like a RedBull sponsored TV.  Shows in the wee hours on the re-broadcast.  Could be time to learn to program the VCR

Retractable bridle

(This topic is in: <- Nov.20 Nov.19 Nov.17 -> )

Peter Birren <peterb> writes:

The retractable bridle for static towing has been in use by several of the
Reel HG Pilots in the Chicago area for well over 10 years.  A large dog leash
reel is attached to the keel forward of the crossbar.  It is usually re-wound
with spectra line which is guided through a rapid link at the back of the
sail's lower surface.  No pulleys are involved.  The rapid link on the end of
the bridle prevents the line from rolling fully into the reel.

2003 XC/Competition calendar

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