APPROACHING PERFECTION

by Dennis Pagen

From the September 1997 issue of Hang Gliding Magazine ©1997 Dennis Pagen. Reproduced with permission

But the smile soon faded when we went up the hill to find winds of over 30 mph. How would the glider handle in turbulence! Would I feel secure with its stability! What about its performance! Most of my doubts were answered soon after launch, as I climbed out effortlessly. Turbulence was mild and I easily penetrated the higher winds aloft to get my start photo. I eventually made goal on this strong crosswind day and walked around the glider with a smile on my face. I stroked the membrane, ogled the clean, curvaceous upper surface, kicked the tires and mused: "I believe Wills Wing has made the perfect glider"

Perfection is hard to come by in my cosmos, so after the first flush of infatuation abated I looked more critically for flaws. I did find a minor point or two which we shall report in due time, but it is clear to me that Wills Wing has fused all the good ideas from their previous gliders with a few new items to achieve a design that approaches perfection.
For your edification we present the WW Fusion.

TOPLESS TOPICS

No doubt every pilot with a pulse has become aware of the topless glider revolution. The promise is improved performance, but this improvement comes at a price. This price must be paid not just in dollars, but also in weight and possibly stability. We shall see how Wills Wing handled these potential problems.

Before we begin, let me list my personal glider desirables in order of importance. These are: safety, top performance, handling, ease of takeoff and landing, light weight, ease of setup, appearance and price.

Safety is most important to me because I fly for fun, and it is not fun to be continually in doubt about a glider's integrity. Controllability, strength and stability are the main safety factors, and these are all tested to a certain degree during the HGMA certification process. The Fusion has passed its HGMA tests handily, but the proof is in the flying.

During the 13+ hours I flew the Fusion at King Mountain I never felt insecure when it came to the glider's structural integrity, controllability or stability -- this, despite a consensus that many of us encountered some of the strongest winds and turbulence in our competition experience. In my opinion the Fusion feels as solid and dependable as any kingpost equipped glider.

Let us look a bit further at the pitch stability question. Without a kingpost a glider cannot have reflex bridles (lufflines). These pitch stability devices are most useful when a negative angle of attack is encountered in a gust or incipient pitchover. Without reflex bridles some other method is required to slow or stop a glider's negative pitching motion. Enter sprogs.

A sprog is simply a glorified washout strut that limits how much the rear of the sail can blow down at the sprog location. Ideally, a sprog should be placed as far toward the glider's wing tip as possible to hold twist in the sail well behind the glider's CG point. However, leading-edge rigidity and strength come into play, so the Fusion's sprogs ended up about 70% out on the leading edge (see photos). The addition of a transverse batten parallel to the trailing edge to spread the sprog's influence, as well as conventional washout struts at the tips, complete the minimum twist-limiting package. To assure you that such a system works, note that many rigid wings such as the Fledgling and later the Swift derive their pitch stability by similarly establishing minimum wing twist, and their pitchover record is admirable.

The Fusion's sprogs are held by a bracket fastened to the leading edge and a cable which limits how far downward the sprog can swing (see photo). The angle of the sprog can be adjusted by unfastening the cable and twisting the sprog tube. The owner's manual clearly outlines this procedure, and proper adjustment must be maintained for safety and ease of control. Incidentally, the term sprog was recently coined at the Pre-World meet in Australia. The term comes directly from a Gottawanna Aborigine dialect and means "aggressive little swimmer."

Other pitch stability systems on the Fusion include the upper-to-lower sail connections, the reflexed root section and the airfoil shape. Notably, the airfoil is thickly cambered with a well-forward high point which leads to good climbing ability and good pitch stability respectively (see sideview photo).

We have spent a good bit of space discussing pitch stability because in many pilots' minds this is the big question regarding topless gliders. In my estimation a properly-set-up and maintained Fusion is as stable in pitch as conventional kingposted high-performance gliders.

FUSION PERFORMANCE

Now we proceed to more fun stuff. It should be no surprise to most that the Fusion will out-glide conventional gliders, as do most topless gliders. But how does the Fusion climb and how does it stack up against the other topless competitors! We have already mentioned that the glider has a climbing airfoil. In fact, rumor has it that the Fusion was constantly compared with the best-climbing glider available during development, and it wasn't released until it matched up. I can report that in my own ham-handed experience I never felt outclassed in climb with my Fusion. More tellingly, many other pilots in hundreds of comparison competition climbs reported a similar experience. The Fusion's climb rate stature is reminiscent of the Wills Wing HP AT which was a hard one to beat in its day.

The other pure performance factors of most interest are best glide and glide at speed. I can report that near best glide speed the Fusion matches any other topless glider you care to pull off the truck. At high speeds I have less definite information, because the only time I used these speeds was when diving into goal, and then I was always alone. I suspect that the fat, forward airfoil hurts the Fusion a bit in this category, but that doesn't concern me since we rarely use speeds produced by pulling the bar to our waist or further. Besides, body position and harness type are as important as anything in this flight regime.

Conclusion: The Fusion is equal to everything out there in the weight-shift world, and pilots with top-rigged gliders will enjoy an increment of performance if they trade up.

HANDLING THE FUSION

I mentioned that my first climb out on the Fusion was effortless, as were succeeding climb outs on subsequent days. But what I didn't disclose is that after I left the mountain on course the VG system was stuck full-on, yet I was still able to stick the glider in a thermal and go up. And, of course, I still admired that wing when the flight was over.

To understand why it got stuck, we must understand the VG system. The Fusion's VG works with levers out at the end of the crossbars that push the leading edges forward by effectively lengthening the crossbar (see photo). This system is very efficient in that it provides a tremendous mechanical advantage. Thus, the VG rope offers very light resistance and the total pull length is not excessive. The VG effect on the Fusion is equivalent to moving the crossbar twice as far as on a Wills Wing XC.

Combine the above-mentioned effective VG with the optional rang on the rear pullback and a pilot can truly dial in whatever handling/performance tradeoff is desired. In the loose VG setting the Fusion's handling can best be described as sweet. Turn initiation was easy and responsive while coordination was, well, coordinated. No tricks, no surprises, no sweat.

Full-tight the glider was essentially the fixed wing it seems to emulate. I had the sissy ring on my glider so perhaps that's why I could turn the thing with full VG. Without this tang the glider flies straight and flat.

I could detect no tendency to wing walk or Dutch roll. However, I aerotowed an earlier version in strong turbulence and did oscillate a bit at first until I worked out the coupling. I expect the Fusion to be moderately resistant to yaw/roll oscillations.

Incidentally, the reason my VC was stuck on is that the VG line got stuck in the keel pocket that wraps in front of the control bar. After that first flight I made sure to keep the VG line under a little tension so it didn't sag and get captured between the pocket and keel on launch. From that point on the VG worked magically.

My first criticism of the Fusion concerns the VG jam cleat that is placed on the corner of the control bar. It is an ingeniously simple and effective device, but I dislike having to reach so far for the line. I would prefer it to be nearer my hand on the basetube so I could put it on and off in a thermal without looking and letting go for too long. This is an important matter when entering a glider-infested thermal.

Conclusion: The Fusion's handling is quite light with a solid feel during turn coordination. The terms "confidence inspiring" and "predictability" come to mind when talking about the Fusion's handling.

GETTING OFF AND COMING DOWN

Taking to the air in a Fusion is a nice experience. The launch itself is facilitated by the fact that the VG system keeps the side cables tight throughout the VG range. The only looseness comes from wing sag. The result is a much more connected feel during launch. You can thus perhaps catch a lifted wing sooner.

Another nice launch benefit is the Fusion's fine static balance. You can lighten up your grip before you launch because you don't have to force the nose down. This characteristic makes the glider seem lighter.

Weight should be mentioned as a slight negative on launch. Those of us used to 7075-alloy kingpost gliders will note an increase in weight with the Fusion. It is said to weigh 76 pounds. At a previous meet there were five different topless gliders lined up in a row. I picked each of them up in succession and found the Fusion, the Laminar ST and the Moyes CSX to weigh exactly the same. So the Fusion's weight is not excessive and is grouped with the lightest topless gliders except for the TR3 which is all carbon graphite.

Landing the Fusion is straightforward and easy. I did it in a crosswind, in gusts, in strong wind and in light wind, as well as with the VG on in strong wind. My conclusion is that the glider lands very easily without an overly-critical flare window. Recreational pilots should not fear that the Fusion will require any more than their usual landing skills to keep them from providing landing field entertainment.

SETUP, BREAKDOWN, HARDWARE AND APPEARANCE

Setting up and breaking down a topless glider involves a few different steps compared to a conventional glider. Of course, there's no kingpost to erect or bridle lines to attach, but there are those lovely sprogs to fasten.

On the Fusion you proceed with setup the same as with any glider until you get the crossbar hauled back and fastened. I found this haul back procedure sometimes difficult at first with wind on my tail, because as with all topless gliders the crossbar has an outrigger that rests on the keel to keep the crossbar and wings from twisting when the crossbar is partially folded. This outrigger can create a lot of friction drag when wind pushes down on the wing. The solution: enlist the aid of a buddy to lift a wing or turn the glider crosswise to the wind.

The holdback attachment in general is not difficult to put on and take off It consists of a fitting with a keyhole that slides over a bolt and into a slot on the bolt head. I sure like the simplicity of this system which has been a Wills standard since the RamAir (see photo).

Once the crossbar is fixed it's time to apply the sprogs. To do this you open the V-shaped lower surface zippers, reach in to grab the sprog, swing it out in position and attach a short lanyard with a clip to the sprog end. The sprog is thus held in the proper place to do its mighty stuff. Inspect the internals and zip the hole closed to complete.

Fusion setup is again the usual: Put in the tip struts and battens, attach the front cables and nose cone. The lower front cables also employ a keyhole tang which I praise. The control bar apex slides forward and back which allows the correct geometry for laying the glider flat on the ground by folding the control bar back.

One final point is to mention the hang strap standoff rocker arm or yoke. This device is a short bar that is propped up across the keel (see photo) which serves to reduce roll pressures like a kingpost hang point. This yoke must be lifted off and put back on its support during breakdown and setup so it doesn't impinge upon the sail.

The breakdown of the Fusion is essentially the reverse of the setup. A minor glitch occurs when trying to roll the sail, since both the sprog and the washout strut are prevented from folding nicely against the leading edge by the internal cloth ribs. However, with a little bit of ingenuity and practice you can achieve a reasonable semblance of a neat package and be proud of your bundled glider.

Before we leave this setup and break down business I should mention that any extra hassle concerning the Fusion is similar to all the topless gliders I have flown (four designs). However, I must point out my second mild criticism of the Fusion. The undersurface battens (three per side) are very difficult to put in due to Velcro tabs which must be pulled out of the way so the batten can be inserted. These tabs often get folded over or stuck in the batten pocket, so inserting these battens requires two hands fiddling and takes about twice as long as it has to. A Wills spokesman said they may change this arrangement.

The rest of the Fusion's hardware and layout is admirably functional. Look at the photos and you will see custom-machined parts and neat engineering everywhere. Note especially the graphite crossbar shape. Its curved tips allow the lower surface sail to under-camber a bit for good lift production. The unique Wills Wing folding base tube comes stock on the Fusion. Also, the downtubes are a new extrusion made exclusively for Wills Wing with an extra boundary layer trip strip.

Perhaps one of the most important Fusion refinements is one that will be little noticed. The Fusion's designer, Steve Pearson, was the inventor of the crescent shaped inserts that allow tubes to be stepped down to any size and thus free designers of hang gliders to more readily follow their imagination. With the Fusion, Steve took the concept one step further. He placed a crescent insert at the end of the inboard leading edge tube with a circular insert further in. The result is that the outboard leading edge is no longer held parallel to the inboard piece, but tilts forward and down. This partially compensates for the usual bowing of the outboard leading edge under flight loads.

Conclusion: The Fusion sets up and breaks down about on a par with other topless designs. Takeoff and landing are easy which makes it better than some designs.

ON FINAL

Wills Wing has been in the business a long time -- since 1973. They will certainly continue their success well into the future if they keep turning out products like the Fusion. This is almost an every-man's glider ('almost" because as yet only one size exists and not every pilot wants cutting edge performance). This is almost a perfect glider.

Before we give you the dry data and specs we should mention a few bonuses that come with every Fusion. For the price of admission you get custom colors which can be a split lower-surface pattern or an asymmetric inlay WW with contrasting colors at the tip. You also get tip inserts and winglets are optional. The glider arrives with Wills Wing's traditional bulletproof cover of 500 Cordura.

I suggest getting the special cross-country bag. It is the best I've seen with a waterproof inside and an easy-to-hide out side color. Each glider is also delivered with an admirably complete and clear owner's manual as well as a spare parts packet, and embroidered hat, a batten diagram, a response form and guaranteed membership in the Wills Wing customer support group. Don't forget the WW Web site which provides owner's manuals, technical support and drawings so you can figure out what part you may need or even what colors to order for your new glider.

If moving up to a new topless glider is your destiny, be sure to test-fly the one that is a synthesis of some of the best ideas that fly -- the Fusion.