Slipstream Downtubes / Control Bars: FAQ

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January 2016. Please note that the parts and configurations described below apply only to Fusion and Talon models. On T2 models, the carbon downtubes with companion fittings and the corresponding Slipstream downtubes with companion fittings share the same wire set.

Wills Wing Slipstream Control Bar and Carbon World Team Control Bar. Competition Performance Streamlined Control Bars

Background

In October of 1999, Wills Wing introduced an all Carbon Fiber, all streamlined competition control bar – designated the “Carbon World Team Control Bar.” This bar featured 19mm width, high fineness ratio carbon downtubes, a fully streamlined, all carbon basetube, and all streamlined hardware fittings. This control bar, in conjunction with low drag 5/64″ diameter front to rear and optional 5/64″ or 3/32″ diameter side wires, was tested and HGMA Certified as an available option on the Fusion 150 SP on April 11th, 2000. The Carbon World Team control bar rapidly became the bar of choice among many of the top competition pilots, regardless of what brand of glider they flew.

In October 2000, Wills Wing introduced all aluminum, 22mm width, “Slipstream” performance downtubes. These downtubes were engineered to be able to serve as a lower cost substitution for the carbon downtubes originally used on the Carbon World Team control bar without any sacrifice in aerodynamic performance. Comprehensive wind tunnel testing of several streamline tubing sections commonly used for hang glider control bars, conducted at the University of Stuttgart, has confirmed the superior low-drag performance and wide angle of attack range of the Wills Wing Carbon and Wills Wing Slipstream (22mm aluminum) control bar sections as compared to other available sections.

Aluminum Streamlined Base Tube

The aluminum streamlined basetube that goes with the Slipstream downtubes became available in January of 2002. It features a deeper bend and better durability than the carbon base tube. If you are planning to substitute the aluminum basetube for a carbon basetube, you will need to purchase the new basetube complete with brackets, plus one additional ball lock pin. The aluminum basetube cannot be used except in conjunction with the slipstream (or carbon) downtubes – it does not fit on the regular streamlined control bar.

Talon and Fusion Upgrades

A complete control bar assembly and wires kit is available for the Fusion 150 SP and 141 SP, and for early model Talons, some of which were produced with regular AT style streamlined control bars. The kit includes everything you need to upgrade to the Slipstream control bar: Slipstream downtubes with brackets, faired aluminum streamlined basetube, low drag 3mm diameter VG rope, mounting hardware and 3/32 coated bottom front, bottom rear, and bottom side wires.

 ID Description Retail Price
40S-2011 Slipstream Control Bar w/Wires – aluminum base
Specify Talon 140, 150, or 160, or Fusion 150 SP or 141 SP or “Blank Wires” for non-WW glider
$ 650.00

 

slipstream_corner_1
Carbon Control Bar with Slipstream Downtube
slipstream_corner_front_2
Carbon Control Bar with Slipstream Downtube, Front View

 

 

Please note that on the Fusion models, the apex bracket shown bolts directly to underside of the keel tube, and replaces the Fusion’s original apex slider and slider track to which the conventional control bar attaches.

ID Description Retail Price
40S-2000 Carbon World Team Control Bar w/Wires
Specify Fusion 150 SP or 141 SP or “Blank Wires” for non-WW glider
$ 1000.00

 

Component Parts Prices

ID Description Retail Price
40F-1511 Slipstream Alum. Basetube Without Brackets
$180.00
40F-1512 Slipstream Alum. Basetube With Brackets
$ 300.00
40F-1412 Carbon Basetube With Brackets
$ 421.88
40G-1441 Slipstream Downtube Without Brackets
$ 67.50
40G-1442/44 Slipstream Downtube With Brackets (L/R)
$ 135.00
40G-1411 Carbon Downtube Without Brackets
$ 247.50
40G-1412/14 Carbon Downtube With Brackets (L/R)
$ 315.00

 

Note: Carbon basetube is equipped with an internal safety cable, and includes an attached VG cleat.  Basetube is not available without brackets installed, (except to OEM manufacturers, on approval) as the brackets are bonded in and the strength of the bond joint is important for the strength of the finished basetube.

Slipstream Downtubes with brackets include retaining clevis pins and safeties and retaining bushings which hold the bottom front and bottom rear wires in place in the fittings.

The Slipstream Downtube with brackets also includes a small bushing which retains the bottom side wire in place when the control bar corner is detached during glider breakdown.

Competition Pilots and Original Equipment Manufacturers

We have special programs and pricing available for supplying these high performance control bars to internationally top ranked competition pilots and original equipment manufacturers. Please contact us at oemsupport@www.willswing.com if you are interested.

Wind Tunnel Testing

Wills Wing sponsored comprehensive wind tunnel testing at the University of Stuttgart of several streamline tubing sections used for hang glider control bars. The results confirm the exceptional low-drag performance and wide angle of attack range of the Wills Wing Carbon and Wills Wing Slipstream (22mm aluminum) control bar sections.

Please click here for the complete report of the testing.

Frequently Asked Questions About the Wills Wing Competition Performance Streamlined Control Bars

Q: Can I use the Slipstream aluminum downtubes as replacement downtubes on an existing Carbon World Team bar?

A: Yes, however the end fittings for the downtubes are not interchangeable between the carbon downtubes and aluminum downtubes, nor are the wires interchangeable. You’ll need to replace the carbon downtubes with Slipstream downtubes WITH fittings one time, and replace the bottom front, bottom rear and bottom side wires. After that you can subsequently replace a broken aluminum downtube without replacing the end fittings or wires. Wire sets are not interchangeable between the carbon downtubes and aluminum downtubes because the front to rear wires sets are attached at a different location on the downtube and are therefore different in length. And, although the new side wire tang used on Slipstream control bars is backward compatible with the Carbon World Team downtubes, side wire sets fabricated before November 15th, 2000 are not compatible with Slipstream downtube fittings.

Q: Now that the Slipstream bar is available, is there any advantage to the original all carbon bar?

A: The carbon downtubes are lighter than the Slipstream downtubes (0.69 lbs per downtube for the original carbon downtubes and 0.46 lbs per downtube for the current carbon downtubes, ) and the current carbon downtubes are also stronger than the Slipstream downtubes. Drag performance is about the same. The aluminum downtubes are significantly less expensive to replace if you break one.

Q: Can I purchase the control bar or parts directly from Wills Wing?

A: Except for OEM manufacturers, or individually authorized top ranked competition pilots, our policy requires that parts orders be placed through a Wills Wing dealer. Click on the following link for a dealer in your area: Wills Wing Hang Glider Dealers

Q: Can the Slipstream bar or the original carbon bar be fitted to non-Wills Wing gliders?

A: Yes, provided the overall geometry of the original control bar is reasonably compatible. The Wills Wing Competition Performance control bars are designed to be rigged at a rake angle of 12 degrees to the “vertical” (i.e. the basetube is forward of the apex such that the plane of the bar is inclined at 12 degrees to a perpendicular to the keel). The downtubes are toed in, and the basetube is angled down 15 degrees relative to a perpendicular to the plane of the bar, which is 3 degrees down relative to the keel when the bar is set at the proper 12 degree rake. These angles are set by the geometry inherent in the fittings, and have been set such that the aerodynamics are optimized across the broadest speed range when the bar is rigged at the specified rake angle. When rigged at other angles, the bar will not achieve optimum aerodynamic performance. There is about a +/- 2 degree allowance where performance is still quite good, but outside of that the performance at some flying speeds will deteriorate significantly.

Most current high performance flex wings will accommodate the proper control bar angle without major changes to the control bar location. It may be necessary to move the control bar apex location forward or aft by up to several inches. (One inch is approximately one degree of control bar rake, depending on the height of the control bar.) On control bar equipped rigid wings, because the control bar is typically much shorter, the normal rake angle is usually much greater. Adapting the slipstream type bar to this application requires a different set of end brackets for both downtubes and basetube in order to provide for the proper rake and toe-in values.

Q: What additional parts not included with the control bar & wires kit does Wills Wing recommend when fitting the bar to a non-Wills Wing glider?

A: Most pilots will be adapting the bar to a glider with a VG system. In that case, we recommend you also purchase the VG pulley bracket, pulley and bolt which secures the pulley to the bracket, which mount on top of the keel directly above the control bar apex. This assembly serves to direct the VG rope down into the downtube. The required parts are listed below:

ID Description Retail Price
20G-1510 BRACKET VG PULLEY KEEL MOUNT $ 22.50
20P-1230 PULLEY HARKN SHEAVE TOP LEG VG $ 3.93
10B-1101 BOLT AN23-10A $ .52

Q: What technical support is available from Wills Wing to adapt the Slipstream or Carbon control bar to my non-Wills Wing glider?

A: Unfortunately we do not have the specifications required to be able to provide finished wires to fit non-Wills Wing gliders, nor do we have the resources to develop or maintain that information. We are offering the Slipstream and Carbon Control Bars and special streamlined hardware fittings to other manufacturers on an OEM basis. In the best case scenario, the manufacturer of your glider will make the control bars available to their customers as a bolt on kit, with wires already fabricated to the proper length. If your manufacturer is not doing that, you can order a control bar kit with “blank” wires. In this case each of the wires will be finished at the end that attaches to the control bar, and the other end of each wire will be blank, and left long enough for whatever length you need. You will then need to rig the wires directly onto your glider to determine the proper length and finish the glider attachment ends of the wires. Your local dealer may be able to provide you with assistance in this area. In addition, Carbon and Slipstream bars have already been rigged onto each of the most popular current non-Wills Wing gliders, so you can probably get some helpful information from another pilot who has already done the conversion. Keep in mind that it is very important that the glider be rigged at the proper angle. When possible, it is normally best to move the control bar apex location, if necessary, rather than moving the basetube location, as the latter would affect the “bar position” in flight and change your perception of how the glider flies as well as affecting your available speed range.

Q: Will my glider manufacturer or non-Wills Wing dealer be able to supply me with replacement parts?

A: That depends on your manufacturer. Check with your manufacturer to see if they plan to offer these bars or replacement parts as optional equipment.

Q: I heard that the Wills Wing Carbon bar was outlawed in CIVL competition. Is that true?

A: This is apparently no longer an issue. The CIVL adopted a set of competition safety standards among which was a requirement that downtubes have a minimum thickness of 22mm. Under that rule, the Wills Wing Carbon World Team bar would not be permitted, although the Slipstream bar does meet that requirement. In October of 2000 we received a report which read, in part:

CIVL Bureau meeting at Pléguien, France
October 13th-15th 2000

Hang glider safety standards

The CIVL bureau has … reviewed the safety standards and has made the following changes for 2001 season (the Plenary meeting being too late):

Pitch stability testing will not be implemented due to the difficulty of field-testing a glider.

The requirement for plastic coating on lower cables has been removed

The minimum width of control bar uprights is removed and replaced with the requirement for all uprights to be part of a glider’s certification (HGMA, DHV, BHPA). The question of uprights will be rediscussed by the committee at the next Plenary meeting, taking into consideration the discussion and input on the CIVL web forum.

These changes will be in effect for the 2002 season. All other safety standards remain as currently adopted.

It has since been reported that at the February 2001 CIVL meeting all references to minimum downtube width were removed from the competition regulations.

Q: How strong are the Competition Performance Streamlined Control Bars?

A: The original configuration Carbon World Team Control Bar was tested on the Fusion 150 SP to a maximum peak load of 1530 lbs (695 kg) and a maximum average load over three seconds of 1423 lbs (647 kg). The bar did not fail in this test, so this is not necessarily the maximum load the bar will support. The maximum average load over three seconds equates to a 6 G load for a 237 lb (108 kg) pilot hook in weight. The original carbon downtube has a compressive strength about equivalent to a 1 1/8 x .083 round tube which for our longest downtube is about 750 lbs. Our standard streamlined downtubes have a compressive strength which is about 15% higher than this.

The Slipstream aluminum downtube is slightly (about 2%) stronger than the original carbon downtube. All Carbon downtubes manufactured since June of 2000 are fitted with an aluminum innersleeve which strengthens the tube significantly, making it slightly stronger than our standard streamline tube. (Note: When we speak of a downtube’s “strength” here we refer to its compressive load capacity. This is not directly related to its resistance to breaking in a crash or under a lateral load.)

Q: How much performance increase can I expect from using the Wills Wing Competition Performance control bar? How does the performance of the Slipstream downtubes compare to that of the Carbon downtubes?

A: Our testing shows about a one point increase in L/D when replacing a conventional streamlined control bar with a round basetube with the fully streamlined Competition Performance control bar. The wind tunnel tests indicate that the slipstream downtubes are as good at reducing drag as the carbon downtubes, and are far superior to any other aluminum downtubes tested.

Q: Does Wills Wing offer an aluminum Slipstream control frame that is a direct replacement for the carbon frame that ships with the large ATOS-C? What modifications are required to use the Slipstream frame?

A: We developed a slipstream control bar retrofit kit for the Atos in July of 2001. That kit included finished wires made to the appropriate dimensions for that model Atos. It used slipstream (aluminum) downtubes, and the Wills Wing carbon basetube.

Subsequent to that, we developed a Wills Wing aluminum streamlined basetube. The aluminum basetube required different end fittings than the carbon basetube. We have some aluminum end fittings that match the rake and toe-in angles required for the Atos bar, but since they were designed for a slightly different basetube profile (not ours), they do not fit the profile of the WW aluminum basetube perfectly. So, in short, we can make an all aluminum performance streamlined control bar with the right rake and toe-in geometry for an Atos, with the only caveat being that the basetube brackets do not mate quite as cleanly to the basetube as they would on a WW Atos bar with a carbon basetube, or a WW Slipstream bar made for a flex wing hang glider.

With respect to the wires, it is our understanding that the ATOS C uses a somewhat different wire configuration than did the Atos for which we developed the bar in July of 2001. For details on the differences, you would have to contact the manufacturer of the ATOS. We can, as an option, provide a kit with “blank” wires – i.e. wires finished at the control bar end and not finished at the glider end, which can then be finished by the customer to the required spec and hardware configuration.

Q: Regarding the uprights used in the aluminum Slipstream control frame: Are they standard faired hang gliding uprights or a custom design unique to the Slipstream frame?

A: Slipstream uprights are made from a proprietary Wills Wing aluminum profile. You can only get them from Wills Wing or from a WW dealer. As a matter of policy, we generally sell replacement parts through dealers only. With respect to the slipstream control bars for the Atos only, we will sell the control bar retrofit kit assemblies, and the replacement parts directly to Atos owners.

Q: Does the carbon Slipstream frame use corner brackets like the aluminum frame or are they integrated into the base tube? If not integrated, are the corner brackets made of aluminum or carbon? Are they the same fittings used for the aluminum Slipstream frame?

A: The slipstream control bar with the carbon basetube uses aluminum basetube end brackets, as does the slipstream control bar with aluminum basetube. None of our brackets are carbon. The end brackets for the carbon basetube are not the same as those for the aluminum basetube, since the basetube profile shape is different. Also, the basetube end brackets on the carbon basetube, even though they begin life as separate aluminum machined parts, end up being, in effect, part of the basetube because they are bonded in during the manufacture of the basetube. On the aluminum basetube, the brackets are bolted in.

Q: What is the availability / delivery time for an aluminum Slipstream control frame for an Atos?

A: We should be able to deliver a control bar within 2-3 weeks from date of order – subject to the limitations cited above (i.e. we cannot produce one with finished wires unless the wire specs required happen to be ones that we already have. We are not in a position to be able to develop wire specs for a glider that requires different wire specs than the ones we already have).

Q: What is the price? I saw the parts list on your web site but wasn’t sure what I needed to include for a complete control frame.

A: The retail price of the complete kit is $750 with the carbon base, $700 with the aluminum base.