IHLGF Home Page

International Hand Launch Glider Festival
June 3-4, 2001

Airfoils

Many different airfoils were used by the planes. With the use of XFOIL by Professor Mark Drela, many designers have been trying to optimize the airfoils for their new HLG ship. The S and SD airfoils, along with other airfoil software sites, can be found at UIUC. The AG series airfoils can be found at the Charles River Radio Controllers web site. Over the past few years we have seen many new airfoils stemming from experimentations with camber and thickness starting with these airfoils.

Some of the standard airfoils were the SD 6063 and the AG series airfoils. Brian Buass and Phil Pearson/MapleLeafDesign use a new series of airfoils developed by Joe Wurts.

General trends:

Many new airfoils, and consequently aircraft designs, address the tasks of the IHLGF. The main goal is to launch high. On the Friday practice day, many pilots were trying to out-launch each other. Generally, these high launches require a lot of practice to accomplish. Some wings failed in compression or delamination. Trying to develop the high launches still further, Joe Wurts delaminated his polyhedral Raptor. Many of us, who are not as physically agile, know the great heights cannot be reached using our skills, so our designs tend to favor ships having lower sink rates. It is always a tradeoff. Times in the contest were comparable. Those planes which were thrown higher often had higher sink rates even though they could cover more ground. Those ships which could not be launched as high, had lower sink rates.

The designer and pilot need to look at the target times required by the contest tasks. For example, if a 60 second target time is required, e. g. Round 1, then a ship which launches to 90 ft needs only a sink rate of 1.5 ft/sec in order to make the 60 seconds. For a ship that can only launch to 60 feet, the required sink rate is approximately 1 ft/sec.

SD6063

AG04

AG08

AG16

AG18

Modified Airfoils:

Modifying an airfoil has, until now, been done by trial and error. Many of the airfoils, like the 6063, are simply thinned in thickness. Sometimes the camber is lowered. In both cases, the intended result is to reduce the drag of the wing. When a designer says the wing using a modified 6063, they generally mean that they took the base airfoil and tried to thin it or reduce camber. As designers get more and more experienced with airfoil software programs, e. g. Xfoil, they are developing more specialized airfoils. Mark Drela and Joe Wurts are among the major proponents for airfoil design. While it may seem that airfoil design is complicated, it is further complicated by aircraft planform and related dimensions. Little ships with small wings do not relate to larger thermal duration ships with larger wings.

For example, the modified Encore wing by John Asplund and Gordon Jennings is based on the AG16 airfoil with the thickness reduced to 6.5% and the camber reduced to 1.5%. Some thoughts on these changes correspond to the need to launch high, penetrate into the wind, and reduce the sink rate. Thinning the section permits faster upwind speeds, and reducing the camber retains just enough lifting ability of the airfoil to support the plane and at the same time it reduces the drag on the wing. Since many of these airfoils are custom, their coordinates are not available.

If you are just starting out in HLG design, my recommendation is to try the AG16 airfoil. This airfoil is a good compromise in all aspects of HLG design, permitting the designer and pilot to concentrate on developing their flying skills. Knowing the flight characteristics of your plane, and feeling comfortable with your plane in all flying conditions is more important than the slight performance gain you might get by playing with the airfoil. Good Luck.

©2001 Crawford-Adams Enterprises All Right Reserved.
Permission to use any of the pictures and information on this CD is Required.

International Hand Launch Glider Festival June 3-4, 2001
Airfoils Many different airfoils were used by the planes. With the use of XFOIL by Professor Mark Drela, many designers have been trying to optimize the airfoils for their new HLG ship. The S and SD airfoils, along with other airfoil software sites, can be found at UIUC. The AG series airfoils can be found at the Charles River Radio Controllers web site. Over the past few years we have seen many new airfoils stemming from experimentations with camber and thickness starting with these airfoils. Some of the standard airfoils were the SD 6063 and the AG series airfoils. Brian Buass and Phil Pearson/MapleLeafDesign use a new series of airfoils developed by Joe Wurts. General trends: Many new airfoils, and consequently aircraft designs, address the tasks of the IHLGF. The main goal is to launch high. On the Friday practice day, many pilots were trying to out-launch each other. Generally, these high launches require a lot of practice to accomplish. Some wings failed in compression or delamination. Trying to develop the high launches still further, Joe Wurts delaminated his polyhedral Raptor. Many of us, who are not as physically agile, know the great heights cannot be reached using our skills, so our designs tend to favor ships having lower sink rates. It is always a tradeoff. Times in the contest were comparable. Those planes which were thrown higher often had higher sink rates even though they could cover more ground. Those ships which could not be launched as high, had lower sink rates. The designer and pilot need to look at the target times required by the contest tasks. For example, if a 60 second target time is required, e. g. Round 1, then a ship which launches to 90 ft needs only a sink rate of 1.5 ft/sec in order to make the 60 seconds. For a ship that can only launch to 60 feet, the required sink rate is approximately 1 ft/sec. SD6063 AG04 AG08 AG16 AG18 Modified Airfoils: Modifying an airfoil has, until now, been done by trial and error. Many of the airfoils, like the 6063, are simply thinned in thickness. Sometimes the camber is lowered. In both cases, the intended result is to reduce the drag of the wing. When a designer says the wing using a modified 6063, they generally mean that they took the base airfoil and tried to thin it or reduce camber. As designers get more and more experienced with airfoil software programs, e. g. Xfoil, they are developing more specialized airfoils. Mark Drela and Joe Wurts are among the major proponents for airfoil design. While it may seem that airfoil design is complicated, it is further complicated by aircraft planform and related dimensions. Little ships with small wings do not relate to larger thermal duration ships with larger wings. For example, the modified Encore wing by John Asplund and Gordon Jennings is based on the AG16 airfoil with the thickness reduced to 6.5% and the camber reduced to 1.5%. Some thoughts on these changes correspond to the need to launch high, penetrate into the wind, and reduce the sink rate. Thinning the section permits faster upwind speeds, and reducing the camber retains just enough lifting ability of the airfoil to support the plane and at the same time it reduces the drag on the wing. Since many of these airfoils are custom, their coordinates are not available. If you are just starting out in HLG design, my recommendation is to try the AG16 airfoil. This airfoil is a good compromise in all aspects of HLG design, permitting the designer and pilot to concentrate on developing their flying skills. Knowing the flight characteristics of your plane, and feeling comfortable with your plane in all flying conditions is more important than the slight performance gain you might get by playing with the airfoil. Good Luck.
©2001 Crawford-Adams Enterprises All Right Reserved. Permission to use any of the pictures and information on this CD is Required.