I was looking through the 1969/70 Aeromodeller Annual at the Coupes eligible for the postal contest. As well as the Deuzio, which I used this year, there is also a plan of a nice looking coupe by Georges Matherat. Georges was very successful with it in competiton. There is no article, and the model hasn't been given a name. At the foot of the page the plan is attributed to Le Modele Reduit D'Avion Magazine.
I now come to the real point of this post. Many issues of this magazine are available for download on RC Bookcase, courtesy of Hlsat. They make very nice reading, with lots of plans, photos, and articles that you don't find elsewhere. I couldn't find the issue with the Matherat article in it, but it was a great reminder of how good French aeromodellers are, and how good the French magazines were. Well worth a look. Mike
You are absolutely right Mike ! A mate of mine gave me the link a few weeks ago and I've looked through half a dozen of them, I'll see whether I can spot the Georges Matherat when I next look.
Peter
That plan was reproduced by Dave Hippwrson in Free Flight Quarterly 94 in part 2 of his "UK Coupe d'Hiver Story" and makes the comment.. Georges Matherat won the French Nats in 1968 with this significant model, that would later be refined into the
very successful series of "A to B" and "Les Trumeaux".
Peter, thanks for that. I certainly would appreciate you keeping a lookout when you're next browsing through Le MRA library.
cvasec, that was a valuable comment. And yes, Dave Hipperson's plan shown in the article, was the same as the one in AeroModeller Annual. However, the mention of FFQ sent me to the bookshelves, and my copy of the Coupe D'HÃver Survey, 2006. There are two plans shown .
The first is on page 32, and is headed Champion de France 1968, and centre stage on the plan, the name Yves Sargentini. I'm afraid I don't know who he was.
The second is on page 54. It is dated 1975, and the model is now called Les Trumeaux, and is by Georges Matherat. It appears identical to the original plan, apart from rectangular wing and tail in plan view. The original had slightly rounded tips at the trailing edge.
There is a bit more to come. Mike
A couple of interesting things. The first is the use of a fibreglass tail boom, which were, and maybe still are, available from fishing shops for those wanting to make their own rods. In the FFQ Coupe survey, for Les Turmeaux the text says that the boom has a "major diameter of 5mm", but careful measurement off the plan shows close to 10mm, which is much more likely. 5mm would be much too whippy. I have several fibreglass booms from decades ago, of different sizes, and testing for bendiness confirms that. Fishing rod booms are normally tapered, so that 10mm at the forward end is not 10mm diam. at the rear end. The boom is about 460mm (18") long. The Andrew Longhurst Couper S which appeared as a full size plan from FFQ, had a 10mm square cross section balsa boom reinforced on the corners by longitudinal carbon fibre strips, to reduce whippiness.. My fibreglass boom, 10mm at the big end weighs a bit under 10grms.
The second is this. The Les Trumeaux fuselage ahead of the motor peg, is drawn with very fragile looking diagonals supporting the longerons. No way would it survive a broken motor when winding. The standard way of strengthening the fuselage was to clad the structure with 1/32' or 1mm balsa sheet e.g. Deuzio. However, for Les Trumeaux, Georges Matherat apparently chose to put an A4 size piece of clear plastic sheet, rolled up, into the fuselage, and then allow it to unroll freely to form a blast tube. This seems a pretty agriculural solution. But maybe it worked. Mike
Attached is the relevant page of the 1969-70 issue of the Aeromodeller Annual, so you may have a better idea of what I'm talking about. Can you tell definitively from this whether the fuselage was clad with thin balsa or not? My interpretation is that it wasn't, but I may be wrong. I should ask Glenn Grell for his advice, but given that cladding does not improve the flight charactistics, only the handling, I suspect he may say go ahead and clad if you want to.
As far as the fat end of the fibreglass boom is concerned, at the bottom of the page it tells us the scale is 1:8. On the page the boom measures 1.2 mm, which means 10mm. in real life. Mike.
Mike
I pulled out my copy of the AM Annual concerned. The 3 view is ambiguous - sometimes balsa parts are shown with "woodgrain" shading, but it is not universal. For example, the prop blades are not shaded, nor is the top of the fuselage. I think that one needs to assume that the prop is balsa, but the fuselage top and bottom are Warren girder spacers and tissue covered, like the port side shown.
As for the area behind the motor peg, I think it is vertical spacers with sheet infill and for that I look at the nose spacer, which clearly is a large piece of balsa, but isn't designated as such.
In any event, I think this is the kind of thing where the rules need to be interpreted in a sensible way and not in a picky way. The design is clearly published before the drop dead date, but not as a fully dimensioned plan. It was expected at the time that a competent modeller could use that diagram and make a "replica" and it wasn't relevant that (s)he had sheeted this area and not that, or used 1/6"hard balsa for this instead of 3/32"medium or used a 6mm fibreglass rod instead of 10mm one (or if (s)he made the boom out of bamboo or even rolled balsa).
I tend to think that so long as the aerodynamics are as per the published data, and the construction is consistent with what a modeller of the time would have done when they made an example of the design, then it should be allowed to compete.
To take another instance, I think it is not a deviation from the original design to replace a curved outline which is made in the original with sheet pieces with a laminated piece or even bent bamboo, so long as the outline is the same. It may be different for a competition for "kit" models - perhaps there fidelity to the methods of the original needs to be closer. But even there, which modeller has not "improved" a kit by his or her own touches?
Another way to test that hypothesis is to ask whether an example of Matherat's design would be disqualified if it was built using tissue-covered spacers and longerons between the motor peg and the boom and then, when it broke just there, it was repaired using sheet between the longerons. I hope that no-one thinks that the answer is that the model has become non-compliant because a repair has been made to deal with damage caused to the original design.
Thanks Jeremy for that comprehensive reply. I think that the logic is impeccable. Mike.