A Parametric Approach for Conceptual Integration and Performance Studies of Liquid Hydrogen Short–Medium Range Aircraft
, Davide Zanetti 2, Karim Abu Salem 1, Vincenzo Binante 2 and Giuseppe Palaia 1
Round 1
Reviewer 1 Report
This is review for the manuscript on “A parametric approach for conceptual integration and performance studies of liquid nitrogen short-medium range aircraft” by Vittorio Cipolla et al. This manuscript describes a parametric approach for the investigation of the performance of short-medium-range aircraft with hydrogen propulsion. I really appreciate the authors for their effort in writing this detailed manuscript. The manuscript is interesting to read. All the assumptions and limitations are well put. To sum up, I recommend accepting the manuscript.
Section 4: Line 1121 – “Figure 23 summarizes the most relevant results……” – should that Figure be 22?
Author Response
Dear Reviewer,
On behalf of all the authors, I would like to thank you for your comments. We tried to meet all the criticisms, replying to the comments received from you and other reviewers. In the attached document, you can find the reply (see text highlighted in blue) and the manuscript with tracked changes.
Sincerely,
Vittorio Cipolla
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper uses the traditional aircraft design method to design the liquid hydrogen short-medium range aircraft. After I read this paper, I think this paper must be improved in the following comments:
1) This paper is a very long article and I think the authors can be cut in some topics.
2) According to comment 1, I cannot know what is the originality of this paper because the authors put a lot of theory, figures, and results.
3) The flight envelope is also very important for the conceptual design phase, I recommend authors put the flight envelope in this paper.
4) What is the design parameter of this work and what is the final design of this aircraft? This information is very important to show our design is successful.
5) In the aircraft design field, I recommend the authors analyze the moment of the proposed aircraft. This data is very important to show the trim condition for this aircraft.
Author Response
Dear Reviewer,
On behalf of all the authors, I would like to thank you for your comments. We tried to meet all the criticisms, replying to the comments received from you and other reviewers. In the attached document, you can find the reply (see text highlighted in blue) and the manuscript with tracked changes.
Sincerely,
Vittorio Cipolla
Author Response File: Author Response.pdf
Reviewer 3 Report
General Comment
In this paper, the authors develop a methodology to analyze the impact, at the conceptual level, that some design parameters associated to a hydrogen-powered aircraft have on its performance. Even though the paper is interesting and covers a current research topic, there are some issues that need to be addressed.
Comments and Question
I would add a brief comment at the end of page 2 on the fact that your Prandtl plane might be an adequate candidate for hydrogen-powered aircraft due to the wider fuselage. A Blended-Wing-Body might explore even further this feature.
In the introduction, I suggest including a brief discussion on the environmental and technological challenges to produce and supply hydrogen sustainably. Even though such issues are not be directly related to aircraft design, these have impact on the viability of a hydrogen-powered aircraft.
From my point of view, it will enrich the discussion if you include the level of detail conducted on the studies reported at the end of sub-section 1.2.
Furthermore, in the introduction you could add a brief paragraph to guide the reader throughout your article.
Please provide a description of the colors used in Figure 5.
To improve the understanding of your paper and help the reader, you can include a flowchart summarizing your design methodology.
On page 13, paragraph 376, (and on page 14, paragraph 383) where it reads “Figure 10” shouldn’t it be “Figure 9”?
Given the fact that you are keeping the same shape, I would suggest to maintain the same static margin (or within the variation estimated for the reference aircraft) to prevent undesired longitudinal motion.
In table 6, you should provide the rational for the factors 0.35 and 1.01 applied to the SFC and engine mass, respectively.
The y-axis label in Figure 20 b has a typo.
On page 42, paragraph 1121, where it reads “Figure 23” it should read “Figure 22”.
Author Response
Dear Reviewer,
On behalf of all the authors, I would like to thank you for your comments. We tried to meet all the criticisms, replying to the comments received from you and other reviewers. In the attached document, you can find the reply (see text highlighted in blue) and the manuscript with tracked changes.
Sincerely,
Vittorio Cipolla
Author Response File: Author Response.pdf
Reviewer 4 Report
1) Concerning the structural materials, three metal alloys have been considered - do they enough to be considered for such a new and important implementation? What are the other structural materials possible for consideration and why they were missed?
2) the same question on insulant materials used in research.
3) In the conclusion section declared: 'the lighter material, i.e. the Aluminium alloy AA2219, although the lower mechanical characteristics is the one which minimizes the structural mass fraction of tanks. The structural analyses have also provided a set of guidelines to assign a value to geometric parameters such as the endcaps aspect ratio (????>0.4), length-to-diameter ratio (?????⁄>1.5) and non-dimensional distance between supports (?????/?<0.8).
Why the authors and readers must be sure that parametric investigation was enough to provide these conclusions? Was the optimization task formulated to solve this problem?
Author Response
Dear Reviewer,
On behalf of all the authors, I would like to thank you for your comments. We tried to meet all the criticisms, replying to the comments received from you and other reviewers. In the attached document, you can find the reply (see text highlighted in blue) and the manuscript with tracked changes.
Sincerely,
Vittorio Cipolla
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
I agree with the author's response.
