Hobbies And Interests
Instructions
Sketch out the basic design of your powered parafoil aircraft. Include the parafoil and the cords that will attach to the airframe. The airframe should be an open frame design, and must include a pilot's seat, maneuver controls, a small engine, at least a 10-gallon fuel tank, a propeller or industrial fan, rudders and three or four wheels.
Calculate the weight of all the materials you plan to use, add the weight of the pilot and include the weight of the fuel. Ten gallons of gas weighs about 61 pounds, according to Boatsafe.com. The total weight of the materials, crew and fuel is the minimum amount of lift your parafoil aircraft needs to generate to fly.
Calculate the amount of thrust your propeller and engine can produce. Use a static thrust calculator and input the propeller diameter and RPMs your engine is capable of producing. For example, a 36-inch propeller turning at 2,000 rpm is capable of producing 18.01 pounds of static thrust, a potential air speed of 18.9 mph with a 0.9 horsepower engine. Actual air speed will likely be lower due to drag.
Calculate the amount of lift your parafoil is capable of producing. Information about the coefficient of lift of your particular parafoil should be included with the technical specifications when you purchase it, or it can be obtained from the company. Use a lift calculator to find how much lift your parafoil can create. For example, a 302-square-foot Jalbert Parafoil moving at 18.9 mph can produce potentially about 860 pounds of lift.
Match your aircraft's loaded weight to its lift to determine minimum speed for takeoff. Assuming a 150-pound pilot; 100-pound airframe, including seat, controls, propeller and motor; 61 pounds of gas; and a 14-pound parafoil, your aircraft must produce more than 325 pounds of lift to take off. Using a lift calculator indicates that such an aircraft using a Jalbert 302-square-foot parafoil will need to move faster than 11 mph to get airborne.
Adjust your aircraft's specifications as needed. A more powerful motor, bigger propeller or larger parafoil may be needed to get the performance you want.