Wind Tunnel Testing of ONERA-M, AGARD-B and HB-2 Standard Models at Off-Design Conditions

Round 1

Reviewer 1 Report

The submission investigate wind tunnel testing of several standard models at off-design conditions. Standard models of AGARD-B, ONERA M4 and HB2. The off-design conditions include Mach and angle of attack range outside of the typical flight envelope of these vehicles. Off-design test were conducted at two different wind tunnel facilities of Military Technical Institute in Belgrade. Overall, the paper is well written and structured.  Test data are well detailed and good agreement was found with available data from other test facilities.  The authors then show extension of these data at off-design conditions, e.g. high angle of attack for ONERA M. In my opinion, the paper could be published in this journal with a few minor corrections.

The author mention the aerodynamic data generation at off-design conditions is beneficial to other researchers.  This reviewer questions what are these benefits- As stated by the authors, standard models have been developed to check data repeatability of different facilities and to provide a baseline for correlation of the results from different facilities. These models are typically tested at design conditions and I am wondering how testing them at off-design conditions benefits wind tunnel testing objectives.  

 

Another issue is that testing at off-design conditions possibly needs a different test facility which needs different model scale and sting geometries. How the authors address these issues and the effect of sting and scaling on measured data?

 

P2 Could you provide a brief description of AGARD-B, e.g.   a generic winged missile?

 

If T-38 is a trisonic wind tunnel and the authors need to test standard models at different Mach numbers why using T35 subsonic wind tunnel? Is it due to high cost of running cases at T-38 test facility?  Or T-35 was used for very low speed tests?

 

I would suggest to move Fig 10 b and combine it with Fig. 11 as three of them compare aerodynamic coefficients obtained from two different wind tunnel.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

I enjoyed reading this manuscript.

My one major comment: the terminology "off-design conditions" is confusing to me. It's not clear, to me, what defines the off-design conditions. Just because a model is tested at a new condition, doesn't make it off-design. Perhaps I would reframe the work in terms of cross validation of different facilities, using standard wind tunnel models.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear friends! I'm happy to see your work! I am very glad that in difficult times for experimenters you are conducting such significant and extensive research!

I am extremely positive about your work! You have illuminated my day! However, I also ask you to make a number of important corrections, which I write about below.

1. The name is too general, it is necessary to add the specifics of the models, for example "Wind tunnel testing of ONERA-M, AGARD-B and HB models at off-design conditions" or something like that. Or "Wind tunnel testing of several standard models at off-design conditions" if you dont want to put the model names in the title. But it needs to be specified.
2. You cannot talk about wind tunnels without mentioning Russian experiments (espesially, TsAGI and ITAM). Surnames such as Kharitonov, Zvegintsev, Borovoy, Skuratiov, Fomin, Bezmenov should be in the introduction, at least some of them. I did not see any links in the literature, this is not good, especially since you yourself know these works very well. Here are just some of them: 
   10.1134/S1531869906010011
   10.1134/S0869864306020016
   10.1117/12.683019
3. The abbreviation VTI must be expanded in the main text of the article (line 76)
4. Line 103: [35], [36] - 1964 is not "Recently" (line 101). Original works should be mentioned, but modern ones should not be forgotten either. Moreover, there are many modern works, including among the authors who are mentioned earlier. You may add that too.
5. You are great fellows for conducting such complex experiments, I am pleased to read your data! But I believe that at the beginning of Section 3 it should be saied that this article provides general information on T-38 and T-35 facilities, a detailed description of their technical characteristics, measuring techniques and principles of operation is given in [...] (add some links). Something like this is necessary add as a reader (like me) would love to know about it. Maybe it makes sense to add a couple of sentences with links to works, which describe the history of the creation of installations and the first experiments carried out on them.
6. Pay attention to Figures 2, 3, 5, 7, 9, 12a, 14a, 15. If they have already been published somewhere, you need to provide links, for example: "Figure 2. The T-38 test facility in VTI, Belgrade [...] ". If they first appeared in this work, then nothing needs to be specified.
7. From which papers were Figures 4, 6, and 8 taken? It is also necessary to clarify the literature. Even if the reader only looks at the pictures, he should immediately understand what was taken and from where.
8. When you take data from other sources on the graph, they must also be indicated in the title (Figures 10b, 11, 12b, 13b-d, 14b, 16b) Otherwise, the reader will have to look for the link in the text himself, this is not convenient.
9. "momtns" on line 249.
10. Why is it correct to compare models with different sizes, as in Figure 11 (M1 and M4)? Explain this to the reader, add a couple of sentences.
11. There is no description of the measurement techniques that were used. It is necessary to add specifics on the methods (schlieren pictures and force measurements). A short paragraph at the beginning of section 5 would be fine. Or write that "you can read more about this in []". But something needs to be added. Better do both. By the way, few people can boast of colored schlieren, this is your advantage.
12. You also need to add a description of the measurement errors and accuracy.
13. I did not find references [20], [38], [42], [45] in the text; you need to identify it.
14. I also advise to define the [21-28] literature more specifically, and not as it is done in the text (line 84). Otherwise it looks like inappropriate self-citations.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors took into account my comments and corrected the manuscript. I am satisfied with the work done and recommend the article for publication.