Construction notes are included in the drawings, which you can download as Acrobat v6 PDF documents in the links below. If you need a copy of the Adobe Acrobat Reader, you can download it free from http://www.adobe.com/products/acrobat/readstep.html.
For some of you, Mark Drela needs no introduction... For the others, Mark has held indoor HLG records and innovated in many aspects of HLG design for the indoor crowd. He is a well known aerodynamicist at the Massachusetts Institute of Technology, and as some of you have read on the Soaring Exchange, Mark is also working to see if he can get his XFoil airfoil design code released to the public domain by MIT.
Understanding the Allegro 2m
The Allegro 2m is the outcome of his RC 2m design analysis work this year. The Allegro is a surprising sailplane, from a couple of perspectives. One is the Allegro's "outrageously thin wing", which has proven so far to be winch-proof. This thin, low drag section, combined with custom designed airfoils (Mark seems to never be satisfied with using a "standard airfoil" for his designs!) leads to a very high performance sailplane.
Drawings and Construction Notes
The Allegro is designed for 2m RES (rudder elevator spoiler) competition tasks. The Allegro uses a set of custom-designed airfoils, tuned for the airframe design parameters. Detailed construction notes and target weights are provided in the plans - please pay close attention to these if you wish your Allegro to have the strength it needs, and the performance it should have!
Allegro 2m tail shaping data and diagram (also see "Accurate shaping of solid balsa surfaces without templates" below - 20 kB Adobe Acrobat PDF file)
Building the Allegro "winch-proof" spar (10 kB Acrobat PDF file)
Building the Allegro "winch-proof" joiner (15 kB Acrobat PDF file)
Accurate Shear Web Cutting (13 kB Acrobat PDF file)
Spar and Joiner Construction Notes:
Airfoil Coordinates and Polars
Polar Comparison with Other Typical Airfoils
Related Construction Notes
Ultra-light tail construction (5 kB Acrobat PDF file)
Here is a view of the Allegro tail
Integrated cloth hinge design (8 kB Acrobat PDF file)
Accurate shaping of solid balsa surfaces without templates (12 kB Acrobat PDF file)
Best of luck, and please let us know how you're doing with your Allegro 2m!
Document Version History
January 27, 2004 - jaf
October 30, 2000 - jaf
October 11, 2000 - jaf
October 8, 2000 - jaf
July 5, 2000 - jaf
June 27, 2000 - jaf