Why are the stock main straps on Wills Wing hang gliding harnesses longer than the DHV standard? Why don't you switch to the DHV standard?
Wills Wing has received many suggestions that we convert our hang loop and harness main lengths to the DHV standard. The Wills Wing standard, which dates back to 1973, is for a 55′ distance from bottom of hang loop to basetube. The DHV standard is 47.25′ (1.2 meter). We have carefully considered this suggestion, and have decided not to change our standard for the following reasons.
1) The required shortening of the harness suspension lines would significantly increase longitudinal compression on the harness adversely affecting comfort.
2) Thousands of Wills Wing pilots with harnesses made to our normal stock suspension length would not be able to hook in to any gliders made with the DHV standard length hang loop. Unlike the present situation where it is relatively easy for a pilot to extend the hang loop length by adding another loop, there would be no easy solution to the problem of a hang loop which is too long for the harness mains. A pilot would have to either change out the hang loop or have their harness mains re-made to a shorter length and their harness re-rigged.
The reason most often given for manufacturers to convert to the DHV standard is that by standardizing suspension lengths across the industry we would eliminate the need to use make-shift suspension system extensions, and by so doing we would enhance safety. This argument is hard to support, however, in light of (2) above. The Wills Wing suspension length convention pre-dates the DHV standard by probably ten years, and there are a great many harnesses in use which are made to this length. While it is relatively easy to lengthen a suspension system safely, ( a single loop of twice the extension length required, hooked to the carabiner, passed through the gliders main and back up loops, and hooked back to the carabiner), it is much more difficult to shorten one safely. In view of the large number of Wills Wing harnesses in the field which are made to the Wills Wing standard length, it would probably create a larger safety problem if Wills Wing were to convert to the DHV standard at this time.
The other problem with the argument in favor of standardizing is that it won’t eliminate the need for custom loops or harness mains. The same harness on two different pilots with different body types will not hang at the same length (increased pilot girth shortens the harness suspension length) and also different pilots have different individual preferences (by as much as several inches) about how high above the basetube they want to hang.
Note that Wills Wing does offer DHV standard harness mains and DHV standard length hang loops as an option on glider and harness orders so that any customer who wants to standardize their equipment to the DHV specs can do so.
Any pilot who needs to hook in to a standard Wills Wing glider with a 55″ hang distance while using a harness made to the DHV harness standard 1.2 meter hang distance, need only clip one end of a 16″ long loop of 1″ tubular hang loop material to his carbiner, pass the other end through both the main and the back up loop on the glider, and then clip the other end of the 16″ loop to his carabiner. In this way, the extension amount is correct for both main and backup, the hook in process is very simple and not ambiguous, there is no larksheading involved and no significant likelihood of not being fully hooked in. The pilot can keep one end of the 16″ loop attached to his carabiner as he moves from one glider to another, and the hook in process is only very slightly more complicated than hooking into a normal loop of the proper length. It is simpler and less confusing than hooking into multiple extensions on mains and backups. (What happens, for example, if he hooks into the longer main and the shorter backup by mistake?) The 16″ inch extension loop becomes a four strand connector of 1″ tubular, and is good for about 12,000 lbs, or as much as the standard carabiners used in hang gliding.
Specifying basetube/downtube options, wehre applicable, for an inventory glider incurs only the additional cost (or savings) of the options.
There are some wear marks or nicks in the leading edge material of my hang glider. How can I repair them?
Our part number and designation is as follows:
25G-1201 CLEAR SAIL REPAIR TAPE #396 EA $30.00
The tape is two inches wide. The length of the roll is at least a couple of hundred feet, far more than a pilot would ever use – it is more of an item that a dealer should have on hand.
A small circle of this tape, about 3/4″ or 1″ in diameter, applied to the outside of the sail should be sufficient to keep the fabric from wearing further. To make clean circles or other shapes we take a section of the tape and apply it to a non-stick piece of paper (such as the peel-off backing of a Wills Wing sticker) and cut the shape with scissors. The tape will need to be replaced periodically, but if you clean off the old adhesive with a dab of acetone before applying the replacement it should last the same length of time (or the same number of flights) as before. One thing to avoid is sharp corners on the piece of repair tape – circles or ovals or rounded corners stay on longer.
We don’t know of any adhesive that one could use to stick dacron to dacron or mylar scrim to mylar scrim for any length of time.
We have noticed that many pilots pack up their gliders quite tightly, binding them close to the frame with the velcro ties – this can only promote frictional wear. We recommend that the glider ties be used only to hold the rolled up sail together enough to put the cover bag on.
How are you achieving the light weight in the Sport 2? I love the sub-60 lbs concept, but am concerned about what was given up and what it will compromise.
How? Simply put, we have more engineering resources and experience at WW than the rest of the industry combined. We own a fully computerized, three component test vehicle, and we’ve performed literally hundreds of structural tests since 1977. Also, the same management team that designed WW gliders in 1977 are solely responsible for product development today. It also helps that the Sport 2 airframe and sprogs are 7075-T6 tubing which no other glider in its class can claim. There are many other details that contribute to the weight savings. For example, we redesigned our Slipstream performance control bar for the U2/Sport 2. we traded 2/10th of a point in glide advantage of the Slipstream for a 1.5 lb weight savings for the Litestream. No other manufacturer even has a performance control bar for an intermediate glider.
The Sport 2 passed the HGMA load test requirements with significant margins and no failures. We know of production gliders as much as 20 lbs heavier that have failed these tests.
All current Wills Wing models use 7075 aluminum in the leading edges, except for the Sport 2 175 and the Falcon Tandem. Why do these gliders use 6061 leading edges? The answer lies in understanding what is different between the two materials, along with what is not different. The 7075 T6 alloy is approximately 75% stronger than 6061-T6. This allows the designer to use 7075 in a thinner wall tubing, typically .035 inches instead of .049 inches, and thus achieve substantial weight savings – typically six lbs in an entire glider airframe. Because of this significant advantage, Wills Wing designer Steve Pearson pioneered the large scale production use of 7075 in hang glider airframes twenty years ago, when 6061 was the universal industry standard, an innovation that some manufacturers have only recently adopted, and in most cases only on their competition class gliders. At the same time, while 7075 is inherently much stronger than 6061, it has the same “modulus of elasticity” or inherent material stiffness. As a result, a leading edge made to the same strength in 7075 will be, because of the thinner wall, somewhat more flexible than an equivalent strength, thicker wall, 6061 leading edge. In most design applications, this is not a problem. However, when designing a wing for the broadest possible range of load carrying capacity, the ability to retain aerodynamic performance and optimum handling qualities across a wide range of loadings can depend very significantly on the degree of stiffness of the airframe. The stiffer 6061 leading edges used on the Sport 2 175 and Falcon Tandem allow these gliders to preserve the designed wing shape more effectively to very high wing loadings, which in turn allows these gliders to more effectively retain their intended flight performance and handling qualities across their larger than normal range of recommended pilot weights.
I really like my old WW hang glider. The glider's frame is in great shape, but the sail is worn out. Can you make me a replacement sail?
The sail on a hang glider is about 2/3 of the value of the glider. In order to ease the burden on pilots who accidentally damage their sail on a relatively new glider, we offer replacement sails for current production gliders at a discount – at a price of 1/2 the price of the glider. If we had the ability to make a replacement sail for an out of production glider, the retail price would be between $1500 and $3000 (1/2 the price of the equivalent model in our current product line). Since you can buy complete gliders on the used market for less than $1500, selling replacement sails for these older gliders doesn’t make economic sense.
In reality, we can’t make sails for gliders that have been out of production for very long. (This is true for the same reason that NASA could no longer make a Saturn V rocket if they wanted to.) Even though we have all the documentation now that we had then, there is too much knowledge about how to make the sail that resides only in the minds of the sailmakers (exactly how to tension and register this panel to that one, etc.) and once the sail is out of production, this knowledge is lost.
The other thing to consider is that when you say you ‘really like’ your glider, you have to remember that what it is that you really like mostly resides in the sail, not the airframe. If you put a different sail on that frame, you’d have a different glider – it would still be the same model, but it wouldn’t be your good ol’ wing.
The easiest thing to do if you think your sail is worn out is to find a better condition used one of the same model and buy that and fly it, and use your old glider as a source of replacement frame parts.
Strings that are too tight really hurt the handling of a glider, while strings that are on the loose side only reduce performance a little. As gliders age, the sails shrink, and this pulls the batten strings tighter and tighter, but so slowly that it is hard to notice. It is a good idea to periodically (annually or biannually) untie/retie, or simply replace, all of your batten strings to help your glider fly and handle properly. This subject is also discussed in the ‘Tuning’ section of your owners manual.
Each glider listed on the inventory list will have an estimate of when the glider can be shipped from the factory. An inventory glider that is assembled, test flown and ready to ship, will be listed on the inventory list with an “Immediate” availability, meaning that it is available for immediate shipment. (That does not mean it will ship immediately – see item 3 – c below.) All other gliders will be listed as “Available:” as of some listed date – the date that we estimate that the glider, if purchased, can be test flown and available for shipment.
A custom glider order will be quoted an estimated ship date at time of order – again this is the date we estimate that the glider will be available for shipment from the factory.
Please keep in mind that:
- All delivery quotes are ESTIMATES only – they represent our best guess based on anticipated production rates and our past experience.
- A delivery quote represents our estimate as to when a given glider will be ready for shipment from Wills Wing to your dealer. It is not an implied promise of the date of actual shipment or of the date you will receive the glider.
- There are many factors that are at least partly outside of our direct control that can affect both the actual shipping date and the date you receive the glider:
- There may be unanticipated delays in production, due to material shortages, equipment downtime, employee absences, etc.
- There may be a delay in factory test flying due to weather or other factors.
- There may be a delay in shipping the glider after it is test flown as a result of consolidation with other items at the request of your dealer, or as a result of a backlog in the shipping department due to fluctuations in the shipping volume.
- There will be some time in transit for the glider after it is shipped from here, and there may be an additional delay after the glider arrives at your dealer in the delivery of the glider to you by your dealer.