The Oz Report

Stalking the Stalker

On Friday (March 2^nd), G.W.  Meadows enthusiastically invited me to drive on up to Quest Air to take a test flight on the new Aeros Stalker.  G.W.  had made arrangements with Aeros to have this one shipped to the US in time for the Expo and USHGA BOD meeting in Indiana in February, even though DHV testing hadn't at that time been completed.  The Stalker has passed the DHV tests, although it won't receive DHV certification until all the associated paper work has been completed (including a user's manual).

Now that the testing part of the DHV certification process has been completely successfully, Aeros will begin producing the Stalker.  They still have to train their work force to assemble the Stalker, so it may take a little while.  Mike Degtoff, who originally purchased a Stalker a year ago, is hoping to get his just before the Flytec Championship in mid April.  All of the first six that G.W.  placed firm orders on have been spoken for or will be demo gliders.

I arrived at about 2 PM and the Stalker was there ready and waiting for my turn.  I was very fortunate in that I got the best time of the day for my two flights, and was the only pilot who had the opportunity for a soaring flight.  This gave me plenty of opportunity to test it out, although, of course, I would have enjoyed the opportunity to get a few more hours on it.  I loved flying it.

You've undoubtedly already read about how nice the Stalker looks and seen earlier pictures that I've published.  It looks just that good in person.  The sail is tight as a drum.

It gets that way (well, it is new) because there is a continuous aluminum tube along the trailing edge that is forced back as the ribs are swung out by a cable that locks the ribs in place.  The leading edge of the sail is behind the leading edge formed by the d-cell, and is held in place by a string in a slot.  You can tighten the sail by adjusting the cable or by adjusting how it is wrapped around the string.

In prototypes the ribs were the kind that folded in the middle.  No more.  Now the ribs made of thin aluminum pieces swing from the back of the d-cell, and are pulled by a cable at the trailing edge.  They each have a Delrin wheel at the trailing edge that runs along the trailing edge aluminum tube.  This makes for a much tighter sail than the sail you'll happen to see on a Millennium, for example.

Greg Dinaauer's Millennium happened to be nearby, so it made for a ready comparison.  Its ribs are folded and pulled from the middle.  Its sail was quite a bit older, but it was clear that it wasn't pulled nearly as tight by its folding ribs (there were wrinkles everywhere).

The Stalker sail had about the same tightness as I found on George Ferris's ATOS when I checked the next day.  But the ATOS trailing edge is only pulled tight at the ribs, so it is a bit sculpted in between ribs.

The trailing edge tube of the Stalker is the axis for the flaps and ailerons.  The spadd (the anti-adverse yaw device) at the tip doesn't use the trailing edge tube and it extends out to the next to last panel.

The leading edges of the Stalker are not covered with a sail, but are Gel coated carbon fiber d-cells.  The Gel coat makes them look very clean, and the Aeros engineers claim a performance gain over cloth covered leading edges (sort of like sail planes compared to hang gliders, I guess).

Competition pilots might think about putting rigging tape over the very thin seam at the rear of the d-cell where it meets the sailcloth. Sailplane pilots put this tape at all seams.

It is clear that Aeros has been using their long development time to build a very nice aircraft.  The wires and pulleys that run the ailerons look very clean and nicely positioned.  All the mechanisms are very clever and well executed.

The stinger fits into the keel and is held there by bungees. You can lift the keel up horizontal and hold it there with the stinger (although I'm not sure why you would want to do this, as you don't stuff in any battens, of course).

In addition to the round keel tube, there is boxed keel of a triangular shape, much like the Ixbo keel, the one I have admired previously. It looks like you can unbolt the boxed keel portion from the tubular keel using allen nuts (useful, if you break something).  The boxed keel connects to the spar behind the d-cells, just as in other rigid wing gliders.

As soon as I got to Quest Air, G.W.  Meadows, John Bolton, and David Glover were there to encourage and help me get into the air.  I couldn't believe just how quickly I was hooked up and off the ground thanks, in addition, to the Quest Air staff.

These guys were full of advice, which I tried to absorb.  I was told to fly in with a light touch as the Stalker engaged the ailerons with the slightest touch of the control bar.  There is no slack that allows the control bar to wiggle, as you'll find on spoileron controlled gliders like the Ghostbuster, Exxtacy and ATOS.

In addition, the ailerons are a bit more progressive in their action, than spoilerons, which tend toward an either on or off control.  On an ATOS, for example, you pull the bar to one side.  In the first inch or so nothing happens as you've just pulled in the slack on the lines (this is done to keep the spoilerons from engaging when you just jiggle the bar inadvertently). Then the spoilerons engage.

Most likely you will pull the spoileron up quite a ways to spoil the lift and initiate the turn, so they've gone from off to almost full on.  You can then back off on the spoileron.

I watched the ailerons in flight and you could watch them go up a little and the opposite side goes down a little and the turn would begin right away.

My helpers told me to have a very light touch as I would be automatically initiating turns if I jiggled the bar while on tow.  I was also told to remember that the bar would be out in the position that Exxtacy pilots are familiar with.  At trim the bar would be just in front of my head.

I was told that I should expect the Stalker to tow just like any other rigid wing glider.  Straight as an arrow.  It does have a bit of dihedral – 1.5 degrees according to G.W.  (This is quite a bit less than the Ghostbuster and ATOS.)

When I got into the air, I soon found out what they meant by a light touch.  I was inducing yaw oscillations just be trying to center myself over the control bar.  It was flying a lot more like a flex wing, and I was over controlling it using my rigid wing "muscle memory."

The PIO was not that bad, as yaw is no big deal on tow.  You can just relax completely your grip on the bar and it will go away.

A few flex wing pilots had a chance to fly the Stalker yesterday.  They didn't notice any of the PIO that I and other rigid wing pilots (Mark P.  and George Ferris) noted.  This is strictly a problem of pilot and glider coupling.

The Stalker isn't like other rigid wings (which are all essentially the same in this regard), and it immediately reacts to the slightest pilot input.  Just the pilot trying to center him or her self activates the ailerons and the glider yaws.

Off tow, I continued to experience my inability to know how to fly the glider.  It was again very similar to my experiences with trying to fly a flex wing after flying my ATOS.  I would continually over control it, when much lighter control inputs were required.  Also, my timing was completely off.

Still, it wasn't all that bad for me, as I slowly relaxed, and let the glider fly.  I didn't have the slightest notion of how to co-ordinate a turn, but I slowed the glider down to 30-mph (trim without the flaps) and was able to turn in 200-fpm lift and gain 1800'.  I didn't have an opportunity to try to fly the glider with other than minimal flaps, except on landing.

I really liked the roll response.  It was great just looking at the ailerons.  I'm not use to being able to watch the control surfaces while I'm flying.

The spadds near the tips have been added to reduce adverse yaw.  There was plenty of adverse yaw left, but I think that pilots can easily learn to co-ordinate their turns in light of the yaw.  Of course, I was in no position to learn how to do this in the hour or less that I was in the air.

I did have a chance to pull in the bar and speed it up to 60 mph.  It was rock steady.  No yawing around at all.  The bar pressure progressively increased as I pulled in going from moderate at 45 mph to strong at 60 mph.  This is completely unlike George's ATOS (before I changed the tuning) which had very little bar pressure at 60 and no progressive increase as I sped up.  I haven't flown George's ATOS since I changed the tuning as I flew the Stalker instead.

Mike Degtoff got three flights on it.  He had never flown a rigid wing before and didn't have any of the rigid wing pilot's built in reactions.  He had a completely different kind of experience on the glider than we did.

I got George to get on the glider and give it a try just before it got dark.  He really liked it like I did.  While I bent one of the $7 sacrificial tubes at the tips when I landed with one wing lower than another, he had a perfect landing with no flare (the preferred method).

George noted the adverse yaw, and the quick roll response. He felt that it would take him a few hours to learn how to coordinate the turns.

He really appreciated the superb fit and finish of the glider.  He did want it with no bar pressure at high speeds.

Paris Williams flew it and thought it handled well.  Just like a flex wing glider.  He did some steeper turns and could get it to co-ordinate well.

G.W.  asked us what we thought about the control bar placement.  You notice right away that the control frame has a wicked rake.  The rear wires are very close to the down tubes, and every pilot was told to remember about those wires when they went to go to the down tubes.  Still they often hit the wires when reaching for the down tubes.

The wicked rake makes for very easy landings.  No one seemed have any problem landing.  G.W.  said to be sure to slow the Stalker way down before flaring.  On my first landing I didn't, ballooned up, but then found it very easy to recover, pull the nose down and then bring it in for an almost proper landing.

Aeros is still thinking about control bar placement.  It is out there quite a ways, and few pilots will be use to the control bar in front of their heads at trim.  They are thinking that they could bring it back three inches.

The reason the control bar is so far forward is to reduce the chance of pilot induced stalls from pushing out the glider and slowing it down too much.  John Borton said that he was able to fly the glider straight at 16 mph, but that it stalled at 15 mph (as measured on a Hall meter four inches up from the base bar on the down tube).  I didn't try to get the Stalker to fly that slow.  I'm just a little nervous about spinning rigid wing gliders.  I'm more than willing to push an Exxtacy all the way out, but I haven't done that on at ATOS in quite a while.  Nothing happened when I did, but still.

When the Stalker was on the ground, George noticed that the nose wires were slack.  It is clear that they aren't slack in flight, and this was a symptom of the keel behind the boxed keel portion bowing near the apex. All the weight of the sail is quite a bit in front of the apex and it is weighing down on the keel.

George mentioned that this would be a possible break point if the pilot had a hard landing and put the control frame on the ground first. George has previously broken the keel on his ATOS and has a very beefed up keel (the broken one) so he is especially sensitive to this issue.  He recommended that Aeros beef the keel up with an insert in the middle near the apex to absorb the stress of a poor landing.

I really liked the little spadds, which are passive controlled devices.  They are just controlled by the ailerons.  Unlike the ailerons, they are pivoted about a quarter of the way up their width so they are also in the below the wing air stream when they are pushed up.

I think that flex wing pilots (the biggest market, after all) are really going to enjoy flying this glider, as they will have a lot less learning to do than rigid wing pilots.  It is a truly beautiful and ingeniously built glider and pilots will love owning it.

I didn't have any way of making a performance comparison. Gregg flew with me on my high speed run and said that it flew at about the same glide as his unfaired Millennium at 60 mph.  I'm guessing that it will have similar performance to the ATOS and Ghostbuster.  It looks a little smaller, so it may be tilted toward better glide and not quite as good a climb rate.  At the moment we have no way of knowing, but that was the general feeling yesterday.

The engineers at Aeros have solved in a many elegant ways all sorts of little design problems and they have advanced the art of hang gliding with this remarkable new wing.  I look forward to flying against it as a worthy competitor.

It was great being at Quest and playing with a new toy.  I can't think of a better occupation for a bunch of old guys like us.  David Glover, the on and off again official photographer of the Oz Report took a bunch of photos, so I'll publish some as soon as he gets them to me.

I invite any comments from other pilots who've had a chance to fly the new Stalker, from G.W., and from Aeros.  If I've unfairly represented any aspect of the Stalker, please set me straight.

Christof coming to Florida

The already very high level of competition at the Florida meets, just keeps getting higher.  Christof Kratzner, the current Class II world champion, will be coming to Florida to fly in the Flytec Championship and the Wallaby Open.  Unlike at the World Championships in Segillo, Italy, or the 2000 pre-Worlds in Spain, he will not be flying an AIR/Icaro ATOS.  Instead he will be flying a Flight Design Ghostbuster.

Christof worked on a caged version of the ATOS.  We assume that he will be flying a regular version of the Ghostbuster, but we are checking.

Christof is the DHV pilot who tests new gliders to make sure that they pass the DHV flying tests.

Christof is also well known as a pilot who can smoke a cigarette while flying (he has a special butane lighter attached to his down tube).  Let's hope that all his aspirations don't go up in smoke.

The death of WRPS

Well it can't happen too soon.  Scott Torkelsen <info>, the Danish CIVL representative sent me an elaborate spreadsheet that used the same (or similar) system what Martin Brunn is proposing to CIVL to replace WPRS. It will be used for the 2001 meets and compared with WPRS.  I've asked Martin to send me a few paragraph description of his proposal, but until I get it, here's Scott's take on the system:

Competitions will no longer be classified as category 1 or 2, but will be valued by the number of top ranked pilots who partake in the competition, and therefore the value of points will reflect the quality of participants.

(editor's note: The linearity of the WPRS system, and the lack of any measure of pilot quality has been its downfall.  I spoke with Mike Barber, the US number 1 ranked pilot – by the NTSS point system, which I administer – and he had an opportunity this morning to look at the latest WPRS ranking.  He just couldn't believe how cockeyed the results are.  I must admit they are the worst I've seen so far.)

Verify GPS

Pete Hammer<hngdog> wrote in to tell about his experience with Tim Cumming's GPS verification software.

It would be nice if he updated the documentation...  or if someone documented how to use it in other coordinate systems (vs the UTM in Oz).  I tried the 3.x program on some 2.0 task files, and they didn't work.  There are either changes in the task file format from 2.0 -> 3.2 that aren't discussed in the old documentation...  or I don't have all the preferences/task files right.  Maybe we need a book, called "VerifyGPS Secrets"...

I could shed some light on the different coordinate settings - basically, the preferences setting in VerifyGPS needs to match the header line in the task file.  So, DMM or DDD vs UTM (that stands for Degrees/Minutes.minutes or Degrees.degrees), which should also be set in the Garmin.  Also the coordinate system - WGS-84 is typical for the US.  When I first got VerifyGPS 2.0 to work, I still had UTM in the prefs, and while it still read DDD tracks, they were consistently about 300 feet off to the SE.  I guess that comes from using a coordinate system optimized for the opposite side of the world...

The underlying settings are really from the MacGPSdmy program - which Tim used as the basis for Verify.  MacGPSdmy actually was written in the US, and had the flexibility to use settings for any coordinate system.  It's docs show WGS-84 settings...  It's mostly Tim's Verify- and Oz-specific docs that stress UTM.

I don't think macGPSdmy exists anymore.  http://www.macgpspro.com/index.html is a newer/different beast.  The older/free macGPS link listed is for a version that won't work on comm-toolbox (i.e.  USB) macs.  http://www.gpsy.com is another one.

Track logs are all more or less downloaded the same, and VerifyGPS task files are actually a very similar format.  It's the little differences that break it.

Re a Mac to Garmin cable, I didn't know anyone made these for the old 8-pin Mac serial.  But every Mac made since 1998 has USB, and no direct serial port.  You can buy a serial port card that sacrifices the modem card on desktop Macs, but a better solution that allows use of PC-GPS cables (ie.  DB-9) is to get a USB-PDA adapter.  Keyspan makes one that works fine with VerifyGPS and GPSy: http://www.keyspan.com/products/usb/PDAadapter/

I went thru the steep VerifyGPS learning curve and was all set up on my powerbook to score our Regionals in Hearne last June, although the weather sucked and no tasks were actually run... (I think it was probably the last rainy weekend before the long drought that made conditions so good later...)

Speaking of vario/GPS cables, has anyone ever done an analysis of GPS/vario/radio interference?  Does anyone make short shielded GPS cables suitable for GPS/vario use?  Other than the vario mfrs? How much shielding is needed?  The one on my Ball GC is coming apart at the DB9 end (might just need to re-epoxy), and I was wondering if it was the cause of my getting bad GPS data points stored.  Maybe it's just the GC (I still have the 99 version s/w).  I have tried to use the 3D-Flightpro s/w, and it doesn't have a points editor, so lame datapoints like 0,0 makes the resulting plot worthless.

WAG for rigid women

Gordon Rigg<Rigg> writes:

As far as I know any female who wants to compete in the second class event would need to have qualified.  ie they would have had to compete in the last worlds or have finished in the top 2/3 of the field in an FAI cat2 event in the last three years.  I think they seem to be accepting a qualification in first class as good enough for second class perhaps, but even then I reckon it could be only Niki Hamilton who would qualify - and she is asking to fly first class at the moment.  I think its highly unlikely that any extra female pilots will end up at the WAG because of the class 2 ruling, though perhaps one or two might more from first class to second class.

daVinci

Ewan McCabe<Ewan.McCabe> writes:

I've just come back from a paramotoring tour of Malaysia, where I met up with Paul Bailey, who makes the JPX based Bailey paramotor.  He and some friends constructed a parachute, based on the DaVinci design, did a balloon drop using the parachute -which was videoed by a PPG pilot.  The parachute worked well, but the plan was always to cut-away and land on a modern chute, this went ahead and the whole operation was completed problem free.  Proving that the daVinci design worked.

If you're interested Paul has his own Web site at www.baileyaviation.com.

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