A specific fancy chapter heading

Question

So, basically I'm working on my memoir. TeX and LaTeX are rather new for me. I really looked everywhere to be able to design the same chapter heading as Walter Appel does in his brilliant book called "Mathematics For Physics and physicists !".

This is how it looks:

I tried using the titlesec package like this:

\documentclass[11pt, a4paper,oneside]{book}
\usepackage{titlesec}
\titleformat{\chapter}[display]
  {\normalfont\huge\bfseries\centering}
  {\begin{adjustbox}{angle=90}\hbox{\chaptertitlename}\end{adjustbox}\ \color{gray}\thechapter}{20pt}{\Huge}  

But I don't know how I can make it look more like Walter Appel does.

I would really appreciate your help. Also, I apologize in advance for my bad English (I'm French) and for the code I provided which is rather not that advanced.

Answer 1

A simple solution with titlesec:

\documentclass[11pt, a4paper,oneside]{book}
\usepackage{graphicx}
\usepackage[svgnames]{xcolor}
\usepackage{titlesec}
\titleformat{\chapter}[display]
  {\normalfont\bfseries\Huge\filcenter}
{\sffamily\rotatebox{90}{\normalsize\chaptertitlename}\,\scalebox{2.24}{\color{Gainsboro}\thechapter}}
  {20pt} {}

  \begin{document}

    \chapter{Some Fancy Chapter}

  \end{document} 

Answer 2

Without using titlesec but with manually redefining the internal \@makechapterhead. This comes pretty close, the fonts differ and maybe the sizes aren't perfect.

\documentclass[11pt, a4paper, oneside]{book}

\usepackage[french]{babel}

\usepackage{duckuments}
\usepackage{xcolor}
\usepackage{graphics}

\colorlet{chapnum}{black!40}

\makeatletter
\renewcommand\@makechapterhead[1]
  {%
    \vspace*{50\p@}%
    \begingroup
      \centering
      \normalfont
      \bfseries
      \rotatebox{90}{\Large\sffamily\chaptername}
      \begingroup
        \scalebox{3.5}{\Huge\color{chapnum}\thechapter}\par\vskip10\p@
      \endgroup
      \interlinepenalty\@M
      \Huge
      #1\par
      \nobreak\vskip40\p@
    \endgroup
  }
\makeatother

\begin{document}
\chapter{Convergence et limites}
\blindduck

\duckument
\end{document}