I'm trying to make a custom header using fancyhdr package. For some reason if I haven't specified the \headheight=3cm, the rest of the document gets wrong header height, even the pages with \pagestyle{plain}. The page with long header is exactly as it needs to be, though. I need to add the header to just one of the pages where a new chapter starts. I just need to use the blankspace without affecting the rest of the layout. I would be happy to use other solutions without fancyhdr package as well.
\documentclass[12pt]{report}
\usepackage[top=1in, bottom=1in]{geometry}
\pagestyle{plain}
\usepackage{fancyhdr}
\usepackage{lipsum}
\fancypagestyle{longheader}{
\fancyhf{}%
\fancyhead[R]{a\\b\\c\\d\\e}
\fancyfoot[C]{\thepage}%
%\headheight=3cm
}
\begin{document}
\chapter{}
\thispagestyle{longheader}
This page looks exactly as it should.
\chapter{}
This page is shifted.\\
\lipsum[1-7]
\end{document}