&gt; You drag those air breathing engines<p>You always drag engines of the last stage all the way to orbit. More, with a single stage to orbit the last stage is the first stage - and SSTO isn&#x27;t quite considered an always loosing idea. More - Skylon has advantage of launching only with fuel - and for rockets oxydizer weights several times more than fuel.<p>Are you sure the drawback you&#x27;re referring to is actually a drawback in comparison to what the industry have?