About this Plan
Adonis. F1A contest glider model.
Quote: "This stylish F1A displayed lots of potential at the Nationals. Over to Geoffrey Archer for the reasoning behind the project.
ADONIS WAS conceived out of an idea to create a model capable of performing respectably in an 'average' contest with the minimum amount of practice necessary on the part of the flyer. Although aeromodelling is thoroughly in my blood, I have relatively few opportunities to fly, especially at all-day rallies.
The model has achieved all that it was assigned to do in most cases better than expected. In particular, its thermalling abilities can only be described as outstanding. I have not bothered to incorporate a circular tow system, but in most cases this is no real disadvantage except in very still conditions.
To help you understand how the design came about, here is some background. I started modelling at ten years of age and have always concentrated on free-flight. Adonis is the product of an eight-year rest from the hobby, or more truthfully, this amount of time with no flying and building, but with brain still thoroughly involved. My 'second beginning' came in 1977. Now having a young family, I found that time was scarce, so in order to give my family the fairest deal, my modelling had to be concise and effective. To achieve the best results I considered it essential to set about the design of my new contest A/2 as one would design a piece of engineering machinery - by understanding first what the model had to do and then establishing the design criteria.
I will now explain the principles as I believe that even the most experienced modellers sometimes miss this fundamental reasoning.
Design considerations: My design critera for Mk.1 Adonis were as follows. Objectives:
1. Model had to thermal freely.
2. Perform well without circular tow (circle tow requires practice); must centre thermals early.
3. Good glide performance.
4. Model robustness; to be capable of withstanding most weather conditions without breakage; also to last a long time and maintain trim.
Requirements to achieve objectives:
1. Thermalling. The model must bank easily and not fly on 'railway lines'; the dihedral system is thus of prime importance. The mechanics of turning the model are critical. This meant: Necessary features:
1.1. Polyhedral wings.
1.2. Large wing tips to support trim.
1.3. Turn to be achieved by warps and all-moving fin (this does not tighten turn as model speeds up).
2. To perform without circle tow: This is again a function of dihedral and general trim. Model must indicate clearly the difference between a gust of wind and thermals when towing. The wing section plays a part here. The choice is a compromise to accommodate other criteria.
Necessary features: similar to above; reasonable tip washout prevents tip stalling on the line.
3 Glide performance: Most consider this to be of prime importance. It is not! What's the use of a good glide if your model flies through weak lift? Also, a light model does not guarantee a good glide; remember, mass is relative to velocity. Velocity is fundamental to the creation of lift over an aerofoil. Adonis Mk.1 weighs 19 oz and glides very well. Mk.2 as featured here) was designed to weigh slightly less at 17-18 oz.
3.1 Good accurate building, clean and tidy presentation.
3.2 Do not make one trim feature fight another.
3.3 Understand the principles of lift in model aeroplanes. Most important: do not use a section just because everyone else does - think about your choice and how it will give its best performance.
3.4 Think about your wing construction - can you improve the wing's performance by building in special features'? There are some in Adonis; maybe you can find them!
4. Robustness:- make sure you think very hard about this Adonis is not for the fainthearted to build, but I can tell you it is worth every effort.
4.1. Wings must not warp when stored or when on a sunny airfield. They must bend, but in a controlled manner. Adonis' wings are very strong, and as you will see, are designed to bend progressively. The wing dowels in Mk.1 were too flexible. Those in Mk.2 are enormous and do not bend, so here as you will see the design accommodates this.
You may have found the above controversial and presumptuous, but it is meant to help in good faith.
Having made a list of criteria and design features, the next stage is a layout plan. I usually only make a 'layout', not a detailed plan, so producing the drawing for this article was painful!
Next come templates for wing and tail sections - including 'female' templates for the leading and trailing edges. These are fashioned to the true section before notching out spar slots. Accuracy is vital..."
Direct submission to Outerzone.
Quote: "Steve and Mary, Here is Adonis, a 79 inch F1A contest glider by Geoffrey Archer, from Aeromodeller January 1988. Scan by Algy2; I have used the span as measured by Applehoney - see
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