Here is a report on a site visit to the BrightStar factory to see the Millenium:
From: "Rick cavallaro"
To: "HG Digest"
Subject: My visit to Bright Star (the Millennium factory)
Recently I was lucky enough to visit the Bright Star factory in Santa Rosa, CA. While there I had a chance to see how the Millennium flight test prototype had been built, as well as how the tooling, methods, and hardware for the production prototype were coming along. I had a chance to take a close up look at all aspects of both gliders and all aspects of their manufacture. Additionally, I was treated to a tour/history lesson of Bright Star's earlier achievements including the Odyssey, the Swift, optional powerplants, etc. This was perhaps the most interesting aspect of the "tour" in that I could see how their manufacturing methods, and the gliders themselves, matured over the years. These guys use everything they've learned over the years (and because we're talking about high tech composite structures coming together into foot launched gliders it was up to them to practically invent the field).
The factory doesn't look like IBM from the outside. They don't have any giant marble marquis with "Bright Star" emblazoned on it, or a tiled entry way and foyer. Unfortunately, they didn't even have the obligatory knock out receptionist behind a big glass table wearing a nifty Burger King style headset. But on the inside it's all business.
The first thing you see are the GIANT molds for the leading edge "D-tubes". These things are big, they appear to be flawless, and they were made entirely by Brian Robbins (Bright Star's lead structural engineer and president). Brian explained to me how the carbon-kevlar I-beam spar is attached to the D-tube and how the D-tubes were formed with carbon, kevlar, and foam to insure absolutely consistent, wing twist, rib placement, etc.
The D-tube molds are a work of art. The front of the D-tubes are formed in perfectly smooth fiberglass molds; and come out of the mold already painted with no need for sanding. Before removing the D-tube fronts from the mold the custom carbon-kevlar I-beam spars are joined to them to complete the structural leading edge of the wing. In the process of building the production prototype Bright Star has built all the tooling and fixtures to insure that every part comes out identical. Unlike flex wing gliders, the handling differences between one rigid wing glider and the next off the line tend to be imperceptible. Given the tooling, fixtures, and techniques Bright Star has developed I have every confidence that replacement parts will snap into place just like the originals. I also have confidence that you won't wait months to get your glider or replacement parts. I think they know this one's going to be popular, so they're tooling up with the idea of producing 30 per month.
Next, Brian showed me the giant oven for curing the carbon-kevlar leading edge D-tubes and thermo-forming the foam used in the D -tubes. They also have a smaller oven for heating the ABS fairing components in order to vacuum form them (cool parts like the wing/tip fairings, and nose cone).
Unlike flex wings each rib is built up from several aluminum tubes. Each tube is formed to define the high performance airfoil designed specifically for this glider. The ribs define the airfoil top and bottom, and the airfoil varies from root to tip. The tubes that form the ribs are riveted together and hinged in the middle. They are then attached with pins to the rear of the D-tubes and remain in place for the life of the glider. No stuffing ribs, during setup, and no removing them at break down. All you do here is pull a single cable at the tip of each wing and each rib extends, and is locked in place, all at once. Once the two tip ribs are pinned in place all ribs are secure and ready to go. When I see the design and craftsmanship that goes into things like these ribs I'm amazed, not that the glider is so expensive, but that they can sell it this cheap (intro price $8500).
I was truly impressed with the lengths they went to to make every part light, strong, consistent, and pretty. I was really impressed with some of the clever features like the elevon mixing mechanism which is basically and extension of the control stick, and is completely enclosed within one of the tubes of the pilot cage. It would be hard to imagine until you see it, but none of the control cables and clevises have to be attached and unattached at setup or break-down. I think this is pretty impressive for a rigid wing glider that folds up and stores in a bag. Features like this not only save setup time, but also enhance safety. If you don't attach and detach your controls you won't forget to.
The Millennium is a more advanced glider than their previous "Swift". However, it's a glider aimed at the general HG market. If you're going to a rigid wing contest bring your Swift. If you want something lighter, cheaper and easier to transport, with TONS of performance you want a Millennium. Everything Bright Star learned over the years is incorporated in the Swift. Everything they've learned from the Swift is incorporated in the Millennium and its tooling (and it shows). It gives me confidence to know that Brian Porter, a member of the Bright Star team, is their test pilot AND current world champion in class II (rigid wing hang gliders). It impresses me that every contestant in the class II world championships flew a Swift. I'm glad that they have a pilot with Brian's skills to make a glider that can comfortably be flown by any intermediate pilot (with minimal training to transition to non-weight shift).
One of the most clever and convenient features is the cage. Most of you probably already know how I feel about the added safety of flying feet first in a rigid cage, but you've got to see this one to really appreciate it. The cage collapses INTO the bag for transport in just seconds. Unlike the Swift, this thing really is transportable. I'm a big fan of the Swift, but I have to admit it's a bit cumbersome. In addition to the 25' box on top of your car you've got to put the cage IN your car. You're just not going to throw a Swift on top of a car with two or three other gliders. Recently I had a chance to fly with the Bright Star guys at Ed Levin (S.F. Bay Area). We put a Millennium and two flex wings on top of a Suburu Impreza to get to the top. This is a 4-wheel drive car (not a truck) with regular luggage racks.
If we had to, I think we could've squeezed another glider up there as well. In addition to flying feet first, this glider provides the pilot with full restraints. You aren't going to swing through the downtubes and smack your head against the keel, and end up with two arms with spiral fractures. In severe turbulence you're not going to end up with a loose hang strap and no control. You're held in place, and the aero controls will continue to work even if you manage some brief weightlessness in big conditions. The clever features, like folding the cage into the bag (without detaching it), make the setup simple and the collapsed volume not much different from your current flex wing.
The winglets pop into place on each wing tip and get pinned in place securely. On the flight-test prototype this process was a bit tedious because I could barely get the little bitty safety rings onto the pins. If the circle clips were a bit bigger and the pins were a millimeter longer this would have been no problem at all. After talking with them about this I think we can expect some very simple improvements that will make this very quick and easy in the production gliders (in fact it sounds like they'll be using straight safety's where needed, and get rid of a couple of them where clever design changes allow). The winglets too, go IN the bag. They employ rudders which are operated both together and independently. They are automatically coupled with the elevons to prevent adverse yaw on turns, and can be deployed together to degrade the glide to get into smaller LZ's. With the glide this thing has (particularly in ground effect) you'll need them if your LZ is tight. If they take this glider to the Morningside glide ratio contest I'd half expect them to go XC. The drag configuration is handled with a single rope like your VG. There's no complicated "mixing" for the pilot to learn.
In light of one of the recent topics on the list I had some questions for these guys. Is the Millennium HGMA certified? Not yet, but they plan to have it certified within 2 years. Why not already? Bright Star simply doesn't have the time and money to write a new set of HGMA certification criteria for Class II gliders at this time (they have been invited to do so by the HGMA); and the current criteria aren't appropriate for a non-weight shift hybrid wing like the Millennium.
So, is it as good as an HGMA certified glider? They say "yes" and they were able to convince me. Because the HGMA criteria aren't entirely appropriate for such a glider, and because Bright Star is extremely concerned with safety, they decided to build the glider to meet JAR 22 (JAR stands for "Joint Airworthiness Requirements"). These are requirements on structural strenth and aircraft stability which sailplanes must meet for type certification. They define the critical flight load conditions, the critical flight speeds, longitudinal and lateral stability for sailplanes and motor gliders. The JAR also specifies handling qualities during stall and ease of spin recovery. The Millennium is designed to satisfy all stated criteria in JAR 22 and the prototype meets these requirements.
So you may ask (or at least I did) which HGMA tests apply and which ones don't? Bright Star felt that the following tests do apply: Positive ultimate load, negative 150 deg load, negative 30 load, 45 deg roll reversal, stall recovery, light wind launch, turns, slips stalls, thermalling, spiral stability, stalls in turns, spin recovery, landing skill, steep dive, minimum L/D (glide ratio). And they designed the Millennium to meet these HGMA criteria.
They felt the pitch stability tests, as done on the test vehicle, couldn't be applied to a non-weight shift glider (but remember they did design it to pass the stability tests of JAR 22 which are more appropriate for a glider with full aerodynamic controls). Frankly, it's just plain difficult to measure things like control-bar pressure when your glider has no control-bar.
In designing and refining the Millennium a number of sophisticated computer codes were used for both aerodynamic and structural analyses. This of course was necessary in order to achieve the weight and performance numbers they wanted. For structural analysis a finite element methods (FEM) program named ANSYS was used. For aerodynamic analyses they used vortex lattice models for 3-D loads and stability derivatives. They also used a potential flow with integral boundary layer model for airfoil design. The folks that work in these fields will recognize these methods as those used by organizations like Lockheed and NASA.
The airfoil design was dominated by the need to keep the D-tube width as small as possible to reduce glider width in the bag. This means the airfoil high point was pushed far forward in the design process. The airfoils operate with little laminar flow (because of the small D-tube size) and the camber varies from wing root to tip to match the lift demands for slow speed flight. Therefore, the root airfoil is cambered to behave like a high lift section and the tip airfoil is nearly symmetric because of its reduced lift load and its need to work well with a control surface attached.
Pitch stability comes from the gliders CG being ahead of the neutral point for all pilot weights and pilot positions. The static stability is no less than 5% (of mean chord) over the flight regime. The wing twist, airfoil camber, and elevon deflection produce the net moment to trim the stable wing at the desired coefficient of lift. Because the pilot CG location is nominally fixed relative to the wing, the glider is unlikely to sustain a tumbling motion if flipped over in turbulence.
The performance is enhanced over that of flex wings by eliminating excess parasite drag. There are no flying wires, downtubes, or kingpost. The wing is rigidly held at an efficient twist angle instead of being over twisted (the Millennium has roughly half the geometric wing twist as a typical flex wing). Winglets are used to provide yaw stability and increase the effective span. Reduced parasite drag and increased span are the key to the Millennium's high L/D (glide ratio).
At best glide the Millennium will achieve about 17:1 without the fairing, and 20:1 or better with. The glider will have a Vne of 65 mph. Without the optional fairing it will maintain a glide ratio at top speed of 7:1 and will be 10:1 at max speed with the fairing. Bright Star will also offer an optional powerplant for the Millennium. Configured with this powerplant we can expect a best glide of 19:1 with a min sink of 190 fpm. The powerplant should produce a max rate of climb of 600 fpm, and will be outfitted with an electric starter. This powerplant will be smaller and lighter than that used for the Swift and will likely produce less vibration (which should increase pilot comfort significantly).
Like the Swift the Millennium will be much more tumble proof than a flex wing. And because the pilot is constrained he wouldn't come free of the control bar if a tumble were to occur. That means that a sustained tumble is very unlikely. Incidentally when you lose the control bar you lose control. When you're constrained, and have the control stick at your right hand you maintain control even when weightless. Like any flex wing it will be possible to stall or spin the Millennium. But flight tests have shown that simply releasing the stick will recover level flight in less than a single turn during a spin (and just as quickly from a stall).
For more good stuff check out the factory website at: www.sirius.com/~mlbco/Millennium.html (case sensitive).