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Pilot Report: Wills Wing Spectrum
By Angelo Mantas
Originally published in Hang Gliding Magazine, June 1992. © 1992 United States Hang Gliding Association. Reproduced with permission.
This review reflects the author's personal experience and assessment at the time of publication.
Most pilot reports lately have been dealing with high performance and intermediate level gliders. However, an entry level glider was introduced last year that begs for a report of its own. That glider is the Wills Wing Spectrum.
Design
Up until recently, Wills' entry level glider was the Skyhawk. Available in 168 and 188 sizes, the Skyhawk featured easy, predictable handling and was a joy to fly. However, since it was a single-surface, exposed crossbar glider, performance left a lot to be desired. Wills decided to make a new glider that combined the performance of the intermediate Sport with the handling of the Skyhawk. This project was given the logical but slightly weird sounding codename "Spawk."
Wills took a unique approach with this wing. While other manufacturers have used low aspect ratios with large root chords to get quick roll response, the Spectrum features the relatively high aspect ratio of 7:1. This is actually higher than the Sport's, which is 6.7:1. Combine this with a planform that is not root-dominant, and the novice level Spectrum looks more like a competition ship.
How did Wills give this high aspect ratio wing novice level handling? First, the Spectrum has a moderate amount of sweep (121 degrees). This helps eliminate adverse yaw, and makes coordinating turns easier. The sweep also provides more pitch damping, making the trim point more definite. The outboard leading edge spars are fairly flexible, allowing the sail to shift more easily. Very long crossbar restraint cables are used — more than twice as long as the Sport's. The longer cables reduce the effort needed to shift the sail when rolling. The moderate sweep, flexible leading edges and long crossbar cables, combined with a fair amount of washout, conspire to give this high aspect ratio wing very mellow and predictable handling.
Wills also searched for a new airfoil with good low speed performance and a gentle stall break, to make landing easy. Since performance was also important, the design was made as aerodynamically clean as possible. The washout tubes, a major source of drag, were eliminated. When the optional wing tip fairings are used, the tips are very clean. Sandwich (Pro) sailcloth is standard on the leading edge. A streamlined kingpost is standard, with streamlined downtubes optional.
Flight Characteristics
My experience with the Spectrum includes 10 hours of flying in extremely varied air on four different 165 models. Flights were foot launched and static and platform tow launched, with both ridge lift and thermal soaring encountered.
My first flight on a Spectrum was at the Whitwell site in Tennessee. Rick Jacob of Sequatchie Valley Soaring was kind enough to lend me a demo for the day. Conditions were of the sled run variety. Standing on launch, I noticed very good static balance, with a very slight tail heaviness. This, combined with tight side wires, made launching very easy. While flying toward the LZ, the left wing was popped up by some turbulence. Most double surface gliders, even easy handling ones like the Sport, require a fairly aggressive control movement to correct for a wing that's been popped up. Giving the glider a sharp punch to the left, I was surprised when the wing immediately went down past horizontal! I corrected to the right, and the glider snapped back to level. I remember thinking, "Wow, this wing is responsive!"
Relaxing a little more on the controls, I flew toward the church LZ, which is a fairly long glide from launch. Arriving with plenty of altitude, I was struck by how easily the Spectrum coordinated turns as I set up my approach. The glider's wide flare window was apparent as I made an easy landing in the light winds.
Since then I have made more than 30 flights in the Spectrum, and I still can't get over what a sweet glider it is to fly. On launch, it balances well and easily maintains the proper angle of attack. In the air, it turns easily and coordinates with minimum input. Adverse yaw is not apparent, even at low speeds. Pitch pressure is moderate, which is good for a novice level glider — lighter pressures would make trim hard to find.
If you start pushing out, the bar pushes back, more and more as you push farther. With this pilot (180 lbs. hook-in weight) I couldn't get the wing to stall break, even with the bar practically all the way out. Amazingly, the Spectrum still has roll control at this stage, even though the root is partially stalled, and will not drop a wing. As you relax pressure, the nose dips, you pick up airspeed, and resume normal flight.
In thermals the Spectrum flies well. In big thermals, it's easy to set a shallow bank angle and just spiral up. Stronger, tighter thermals require more attention to maintain a steeper bank. Notice I said attention, not effort. Although you have to make more adjustments in strong thermals, the low roll pressures make these adjustments pretty easy. Ridge soaring is a piece of cake. Because of its great low-speed handling you can really max out the sink rate.
Performance
The Spectrum's performance is similar to that of the Sport. Sink rate is about the same, as is best glide. At speed (30+ mph) the Sport shows an advantage. This is probably due to the Spectrum's more flexible leading edges and greater washout. When you consider that the Spectrum is rated for Hang I pilots, this could be the best performing entry level glider available.
This may seem like a broad statement, but when flying with other gliders I have often been "top of the stack," even when flying against intermediate and competition gliders. One day last summer, fellow pilots Chris Worsing, John Mitchell and I went cross-country on a no-wind day. Chris was flying a Formula, John a Magic IV, and I was on the Spectrum. I ended up with greatest altitude gain (4,500'), highest altitude (5,700' AGL) and longest distance (14 miles). I was at 3,000 feet and climbing when I got the bad news: land or find my own ride back. Reluctantly, I cored some sink and landed.
On another day I was test flying a different Spectrum in light conditions. Below 2,000 feet the thermals were small, tight and hard to work. Off tow at 1,500 feet, the glider's easy handling and quick response allowed me to max out what little lift was available. As I started climbing, the lift opened up, and by 3,500 feet I was climbing pretty well. I was also drifting downwind, and since I didn't have a driver that day, I left the thermal to head back to the LZ. No one else got above 3,000 feet that day.
Handling and Performance
After the cross-country flight I mentioned earlier, Chris and John tried to figure out how I did so well on an entry level glider. Pilot wise, the three of us are pretty equal, and they didn't believe the Spectrum had better performance than their ships. They finally decided the Spectrum's easy handling made it easier for me to work the thermals.
No argument from me. In the headlong quest to get higher performance, many pilots are actually hindering their flying by using gliders too advanced for them. Although many of the newer competition gliders feature light bar pressures, they still require precise control input to maximize their performance. The most advanced glider in the world loses its advantage if you slip it in turns. Rob Kells comments, "Forty percent of the gliders we sell are HP ATs. That number should be closer to 10%."
For those only impressed by big numbers, consider Dan Skadal's 100+ mile flight on a Spectrum last summer.
Other Info
The Spectrum comes in two sizes, 165 and 144. Although the 144 is rated to 210 pounds, I would recommend the 165 to pilots hooking in over 170 pounds. The smaller glider supports weight well, but this extra weight means higher takeoff and landing speeds, and Hang II's like gliders that land slow. Novice pilots should make sure all initial flights are made at sites gone through the certification process.
The new AT hardware neatly solves the problem of control bar disassembly. Each control bar leg apex is fully hinged. Now all you have to do is release the nose wires and pull the glider forward as the control bar pivots back. The hinges also make the control bar easier to set up.
Another thing I disliked about my Sport was the inability to set it up flat — the glider could only be tensioned from underneath, while standing on the control bar. Unfortunately, this is not remedied by the new hardware. The Spectrum must be set up standing. Many glider setup areas are not sheltered from the wind, and the ability to set up the glider flat would be a real plus.
As mentioned earlier, the leading edge pocket is made of "pro" sail cloth, a sandwich material which extends life and makes a smooth leading edge curve. To keep the handling in the easy range, heavy trailing edge cloth is not available (although you can get 205LL, a slightly heavier cloth).
The frame is made of 7075 aluminum, yielding a strong and lightweight structure. Hang II's will appreciate its 61 pounds (54 for the 144) when they lug it up the training hill.
Summary
As you might have guessed by now, I love this glider. Last summer, when I was telling pilots I might want a Spectrum of my own, many of my cohorts looked at me like I was from Mars. Why would I want a lowly, novice level glider? But hey, I flew 14 different gliders last year, and my best flights were on Spectrums. Wills chose the name "Spectrum" because they felt this glider would appeal to a wide variety of pilots. Whether you're a novice looking for a first glider or an advanced "leisure class" pilot like myself, the Spectrum has a lot to offer.
Thank You's
I'd like to thank Gary Solomon for letting me use his Spectrum while he was in Australia, Michelle Worsing for chasing us on that cross-country flight, and John Enrietti, who risked being fired from his factory job by loaning me a brand new Spectrum for a test.