Letters to the Editor: A Reply by the Author to Mr Cleaver of the British Interplanetary Society— Further Correspondence on Flow through Convergent‐Divergent Nozzles

To the Editor, DEAR SIR, In a letter, which has just come to my notice, published in your October 1951 issue, Mr A. V. Cleaver advocates the use of sub‐orbital refuelling techniques as a means of rendering interplanetary flight an economic proposition, and suggests that the importance of this factor was underestimated in the above paper which was reprinted in your August issue.