DESIGN AND DEVELOPMENT OF THE SWIFT: A FOOT-LAUNCHED SAILPLANE

 Abstract

This paper describes the development of what might be considered the first successful ultralight sailplane.The SWIFT is a high performance foot-launched glider, designed to combine some of the convenience of hang gliders with the soaring performance of sailplanes. It takes off and lands like a hang glider, yet maintains exceptional performance at high speeds, achieving a lift-to-drag ratio of about 25:1. Although it is a fullycantilevered rigid wing with aerodynamic controls and flaps, it is light enough to launch by running from a hillside and is easily transported on the top of a car. This paper describes the design, development, and flying of this unique aircraft. Introduction and Background

 Introduction and Background

Pioneers of heavier-than-air flight were inspired with the idea of being able to fly like birds – not for the purpose of efficient, high-speed transportation, but for the shear freedom that such a capability would permit. This was the motivation for, and is the appeal of,modern soaring aircraft such as paragliders, hang gliders, and sailplanes. Although the performance of sailplanes has increased dramatically over many decades  so that lift-to-drag ratios of 60:1 have been achieved and 1000 km flights are possible, certain aspects of high performance sailplanes seem counter to the vision espoused by Lilienthal and others [1]. Especially for a group of graduate students in the San Francisco Bay Area, the cost of sailplane flying, along with the long drive to an airport that supported such activities, meant that achieving the goal of bird-like flight was only somewhat more realizable than it was 100 years ago.

How To Make Traditional Boomerangs

Construction of traditional Australian boomerang (for right hand)

Instructions how to make traditional boomerang
1. Take plywood sheet of 12mm thickness. Draw boomerang contour pattern as shown in picture above. The 107 degree angle size is not critical, just optimum. It can be more or less than 107deg. Chord length near the center of boomerang = 80 mm, and 60 mm near tips. Make wing chord length few millimeters wider as is required, because it necessarily reduces during sanding process. Also make some access length at boomerang wings tips, as it possible, that you will have to cut them during tune procedure of the boomerang.
Note:
If you make angle >>107, consider that rotation plate becomes small and it can be difficult to keep the
boomerang spinning.
If you make angle of about 90 degrees, the boomerang flight trajectory circle radius is minimum. Angles
<90 deg and >90 degrees increase circle radius.
2. First what you have to do is to sand dihedrals of wings. You have to make decision were is top and
bottom. Put plywood boomerang on flat table and see if the tips are up or down. The traditional Australian boomerang has positive dihedral. The best choice is to find position in which the boomerang wings tips are up. (Do not care about that if your plywood is absolutely flat).
Remove some material from boomerang bottom at distance of about D=70...90 mm from both tips. It can
be asymmetrical, but condition A+B = 14 mm should be satisfied.
Note:

Preflight and Ground Operations

Figure 6-1. Wing stand used during glider assembly.

Operating a glider requires meticulous assembly and preflight. Proper assembly techniques, followed by a close inspection of the glider using checklists contained in the Glider Flight Manual/Pilot’s Operating Handbook (GFM/POH), are essential for flight safety. In order to ensure correct and safe procedures for assembly of a glider, students and pilots unfamiliar with glider assembly should seek instruction from a knowledgable glider flight instructor or certificated private or higher glider pilot. Safely launching a glider requires careful inspection, appropriate use of checklists, and quality teamwork. Launch procedures should be carried out systematically and consistently each time you fly.
ASSEMBLY TECHNIQUES
While preparing to assemble a glider, consider the following elements: location, number of crewmembers, tools and parts necessary, and checklists that detail the appropriate assembly procedures. The GFM/POH should contain checklists for assembling and preflighting your glider. If not, develop your own and follow it every time you fly. Haphazard assembly and preflight procedures can lead to unsafe flying conditions. Before assembling a glider, find a location that shields the project from the elements and offers enough room for completion. Wind is an important factor to consider during an outdoor assembly. Each wing is an airfoil regardless of whether or not it is connected to the fuselage; even a gentle breeze is enough to produce lift on the wings, making them cumbersome or impossible to handle. If assembling the glider in a spot shielded from the wind, great care must still be taken when handling the wings.
When performing the assembly inside a hangar, ensure there is enough room to maneuver the glider’s components throughout the process. Also, consider the length of time you anticipate to complete the entire procedure, and choose an area that allows complete undisturbed assembly. Moving the glider during assembly may cause parts or tools to be misplaced.