Many thanks for the compliments, vB, Lucky13, Aaron and GrauGeist.
I have started its modelling in early October.
I first thought to begin my work from the appearance as Ross game me his sufficient data but re-thought "When I have finised the appearance, I will be satisfied with it and no more working on it".
The difficulty will be the rear parts as I have to understand which gear has which role first.
My first modelling liquid-cooled engine was Lorraine Dietrich12EB.
The experience is useful for the Merlin this time.
So mechanical engines always fascinate me.
Thanks.