Coupled Aerodynamics–Structure Analysis and Wind Tunnel Experiments on Passive Hinge Oscillation of Wing-Tip-Chained Airplanes
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis work studied the wingtip-connected configuration, which is an interesting topic. However, there are some issues need to be addressed before it can be considered for publication.
1. 1. Introduction’s structure is abnormal. It starts with the introduction of this concept, but without citations. I would suggest to read some other papers and restructure the introduction section.
2. The structure of the literature review in the introduction section is not clear. Its hard to follow and missing a clear logic. Its recommended to summarize these literature into several paragraph with clear intention, thus the readers can get to know what has been achieved and what has not been achieved in this field. In addition, after reading the introduction, I cannot see the shortcomings of the current studies, i.e., I cannot see the necessity that you are doing this research.
3. This is an aeroelastic modelling work. How did you calculated the beam properties from the 3D wing, how many beam nodes did you take into account? Where is the beam stiffness matrix? How did you couple the aerodynamic and structural models? Coupling methods? Iterative loop?
4. Neither in the introduction nor in the conclusion can I find the statement of the disadvantage of this concept. Whenever talking of a novel concept, its necessary to point out the shortcoming/challenges, especially the ones revealed from your studies.
Comments on the Quality of English Language
Acceptable
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral Comment
In the paper, the authors study an innovative concept of wing-chained aircraft to increase the wing aspect-ratio. I found it very interesting, however, I have some suggestions to improve the discussion and the description of some steps that could have been more elaborated. Please see the comments, suggestions, and questions underneath.
Comments, Questions, and Suggestions
I would suggest adding references to better support the advantages associated to the studied concept (sub-section 1.1).
I would suggest adding a discussion on the existent disadvantages and/or limitations of the concept proposed.
What about the flight dynamics and control? Is such a unconventional aircraft design more prone to aeroelastic phenomena such as flutter, limit cycle oscillations, buffeting?
Even though you have a nomenclature section I would recommend introducing the variables also in the main text to help the reader.
I would suggest adding references to better support the comparison between these aerodynamic models (sub-section 2.2).
VLM doesn't capture well drag, and despite drag isn't typically a major concern for most aeroelastic applications, it might lead to unpredicted unsteady phenomena. For this reason, I would suggest adding a brief comment to the text about this point.
Have you considered using another experimental method to compare with the one used?
Please provide a reference to support the Cdswing value in equation 26.
Did you perform several measurements of the swing tests to estimate the standard deviation and mean of the damping coefficient?
Why have you noticed such a high standard deviation in the experimental results shown in Figure 23?
Since there are large differences between experimental and numerical results in Figure 26, I would suggest commenting this observation in the paper.
Have you considered performing an experimental modal analysis to identify the modal parameters your chained wing?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThanks for your efforts and the manuscript now looks good!
Comments on the Quality of English LanguageAcceptable
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have addressed my concerns.
