Interesting experiment . but to put it in the sort of terms of a peer review on an academic paperThe research addresses important current issues with regard to induced drag and engine efficiency in a key area to the development of efficient single stage to orbit vehicle architectures . Whilst the results section clearly demonstrates a difference in drag models and their impact on vehicle performance in the early stages of suborbital flight , the data from later stages of the flight test highlights significant flaws in the methodology . Specifically the design of the methodology to show relative performance between two vehicles with and without rear exhaust cones has not taken into account the effect of exhaust of one vehicle at a higher altitude upon the performance of the second trailing vehicle and as such introduces additional variables into the experiment that may be statistically significant in the result . Whilst the experimental results may show an initial benefit , the exhaust effects of the lead vehicle have the potential to obscure the effects of a weight differential and resultant increased thrust to weight ratio in later stages of the flight once atmostpheric drag losses become reduced . As such the conclusions of the research , whilst offering important insights to this research area are not fully supported and the review panel is therefore of the opinion that the paper should not be accepted for publication until these issues have been addressed .