Performance and Weight Parameters Calculation for Hydrogen- and Battery-Powered Aircraft Concepts

Round 1

Reviewer 1 Report

The paper has sound scientific merit and is written well. There are a few things I'd like to see improved:

- The manuscript is too long. I believe that there are some sections of this paper (4,5, and 6) could use consolidating to make it more readable.

- The list of symbols and abbreviations should be moved to the beginning of the manuscript.

- The presentation of results can be improved by consolidating the graphs for the various trade studies and by using more tables to represent results.

- I'd also recommend restructuring section 4 and 5 to include tables with the governing equations and relegating the actual derivations to an appendix if needed. This will improve the flow of the paper as the current derivations feel repetitive.

Author Response

Thanks for the article reviews. The answers to your comments are processed in the attached document.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors present a low fidelity model exploiting aircraft database to retrofit existing aircraft to hybrid and hydrogen-powered aircraft. The study is required for the literature; however, the quality of the work needs to be increased. Assumptions are not very clear, and the discussion needs some modification. The introduction of the paper must be improved to let the audience have a comparison of the work with the literature. Some of the models can be replaced to increase the fidelity of the study such commercial gas turbine models. The paper length can be reduced significatly. Comments are provided in the attached file.

Comments for author File: Comments.pdf

Author Response

Dear reviewer.
Thank you for your comments on our article. The answers to your questions are elaborated in the attached document and incorporated in the manuscript after revisions.

Author Response File: Author Response.pdf

Reviewer 3 Report

The article focuses on calculating the parameters for hydrogen and battery-powered aircraft, which is a very current topic. The article has overall good quality, but can be improved:

- the introduction is very short and the state-of-the-art description shall be extended;

- in the introduction, some ideas are not supported by citations;

- at the beginning of chapter 2, battery and hydrogen will probably not produce thrust - the sentence shall be reformulated;

- English shall be checked overall;

- there are missing links to figures and diagrams, all shall have links in the text;

- in table 1, there are missing fields, which shall be filled (even by N/A);

- the article shall be written in passive;

- every abbreviation in the text shall be explained in the first use;

- some figures and diagrams need better resolution quality (Fig. 4, Diag. 5...);

- equations in subchapter 4.5. and 4.6. shall be reduced, many of them are not necessary for understanding;

- on line 492, the part "...hydrogen-powered aircraft is so light that even..." doesn't make sense in the context, "hydrogen in the" is probably missing;

- in chapter 5.1.1., the authors use as a reference aircraft outside CS-23, article is focused on CS-23, which is mentioned by the authors, this discrepancy shall be corrected;

- same applies to 5.1.2.;

- there is a missing Table with "validation" of the model for Bristell aircraft, in chapter 7.2;

- chapter numbering is wrong between 5.1.10. and 6.1.12.;

- chapter focused on discussion is missing and shall be added;

- conclusion shall be expanded (and in it on line 868 is unnecessarily a bracket "(" ).

Author Response

Thanks for the article reviews. The answers to your comments are processed in the attached document.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Many thanks for considering the previous comments. I would like to highlight the fact that the introduction still fails to pinpoint similar low fidelity studies in the literature. The references discussed are more general rather than discussing similar methodologies or other different methodologies and compare them. 

Author Response

Reviewer 3 Report

Corrections are OK. Section containing discussion is appropriate in journal articles, moreover in this type focused on modern ideas.

Author Response

Thanks for the comments on the revised version of the article.
The discussion was incorporated into the revised version of the article.

Round 3

Reviewer 2 Report

Thanks for addressing the comments. 

Other methods could have been added to the introduction of the paper as well.