Sectional Leading Edge Vortex Lift and Drag Coefficients of Autorotating Samaras

Round 1

Reviewer 1 Report

This paper aims to quantify the aerodynamic parameters that can describe the lift and drag of the Sycamore seeds for a range of wind speed conditions. It seems that the low-order BEM model was able to generate a good agreement with the experimental measurements in the prediction of both rotational speed and thrust. While there are lack of the reason for choosing these three Sycamore seeds A, B and C，and are they representative in size parameters? For example, the change of aspect ratio of wing will significantly affect the LEV structure. Flexible deformation, spanwise bending, different camber and thickness of wings will also affect the LEV. It seems more convincing to do more wind tunnel tests of Sycamore seeds with different aspect ratios.

Author Response

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Reviewer 2 Report

This is an excellent paper. It has an insightful review of the relevant literature, presents a novel experimental method, and applies appropriate and detailed analysis methods to assess two competing models of forces acting on autorotating samaras with leading edge vortex lift. The results will be of significance to those researching samara flight, which is of interest due to the unwanted spread of certain species by self-seeding, and to others researching other flight applications in which LEVs are important. It is clearly and beautifully written throughout. The work is comprehensive, experimentally and theoretically.

 

I suggest addition of a short section discussing limitations in the wind tunnel technique, particularly:

Whether the addition of the seed clamp changes the axis of rotation (coning angle).

Whether the wake of the oval shroud and/or the drag due to the seed clamp and/or the  friction due to the bearings (this last being probably negligible) changes the relationship between thrust and rotational speed.

I suggest the following minor changes:

Line 42 don't need word 'intricate' (it is not excessively complicated)

Line 122 I think you can delete the words "profile of" without loss of meaning

Fig 3 typo "planfrom"

Line 441 delete word "separations"

 

 

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Reviewer 3 Report

Needs proof-reading e.g. line 313, 251, Figure 6 has text/description overlaping the illustrations, footnote 8, pg. 22.

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Reviewer 4 Report

comments attached

Comments for author File: Comments.pdf

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