By Kimball Livingston
Richard Jenkins had a good session in early April at Ivanpah Dry Lake, recording 10 runs above 90 mph and peaking at 98.3 in his quest to beat the 116 mph record held since 1999 by Bob Schumacher in Iron Duck.
Richards is now on hiatus until May, when he hopes to find a smoother surface on any of several dry lakes farther north. The heavy rains of 2004-05 have made the surface at Ivanpah, which is always cracked, rougher than usual.
How it's done: Low-end speeds are an issue for Windjet, so a truck pushes the craft into its performance range, and then Jenkins accelerates away. Windjet'scomposite structure is mostly carbon fiber, with some Kevlar reinforcing to protect the pilot capsule. Light weight is not necessarily an advantage on land, however. He's going to add lead to help hold the boat down, so that he does not have to use too much aerodynamic downforce from the airfoil sections over the axles.
To quote: "Due to the poor traction of the dirt surface, (compared to the tarmac, which the craft is set up for) we are experiencing a lot more sideslip and hence a lot more drag. To counter the side slip, we are having to use a lot more aerodynamic downforce than normal, which in turn causes more drag. The simple solution to this is more weight inserted into the fusalage. This, combined with a couple of other minor alterations, should put us in very good shape for record speeds. Changing from a smooth tarmac surface to the desert, is a bit like trying to drive an F1 car on a rally car track, so there were always are going to be some neccessary changes, but luckily it appears these are all relatively minor."
This is a new wing arrangement for the craft. Jenkins said that he had been using a three-part wing that provided better low-end (starting) performance but expects better high-end performance out of the new two-part wing.You can find more detail at Windjet.
Record holder Iron Duck
Ivanpah Dry Lake is the place were Bob Schumacher set the current landsailing speed record of 116.7 mph on March 20, 1999 on the asymmetric, port tack-favored Iron Duck. In fact, I'd say that port tack is more than just "favored" as this centerline picture shows.
Designer Bob Dill holds a second-fastest time in the same machine at 112.3 mph. Winds at the time were 25-30. Dill (2005 president of the North American Land Sailing Association, did not bring out the Iron Duck from his home in Burlington, Vermont to reenact the scene snown below from the record year of 1999. If Jenkins should succeed in 2005, maybe we'll see the Duck again in '06.
There is not a lot of published detail about the engineering of Windjet, but Iron Duck is an open book. Here are some Iron Duck facts:
Length: 39 ft
Wheel base: 30 ft
Weight: 1600 lbs. ("after capsizing the Wood Duck in 1994, adding extra steel was too easy")
Moderate aerodynamic hold-down from the axles.
Tubular metal frame
White ash axles
Plywood, foam and fiberglass fairings
Wing: Hot wire cut foam under 1/8" plywood in the back and fiberglass over the nose.
Field assembly: Duct tape
Wing Height: 23 ft
Wing :71 sq. ft without flap, chain driven from hand wheel.
Tire life: to 2 days.
Steering: double cable, foot operated.
Designer: Bob Dill
Design inspiration and advice on winged landyachts: Clarence Rothtock (Scorpion), Phil Rothrock (all his boats), Chauncey Griggs (Schazaam), Kent Hatch (several boats).
Builders: Bob Dill, Anders Toft, Bob Schumacher, Jerry Manock.
Time invested: About 4000 hours since 1993
Construction Cost: About $6000 for two boats (labor rate =$0.00/hr)
Travel/Transport Cost: About $10,000 since 1994
Sponsor: The Robert Dill Charitable Fund for Overweight Birds (any and all donations gladly accepted)
On that note, Bob, my check is in the mail.