Talk:Parasitic drag

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There is something basically wrong in aerodynamics

Dear Interested Reader, I invite you to compare the CDo of an F-104 Starfighter (=0.0172) and that of a B-58 Hustler (=0.0068), when these are calculated using the wing planform area as a reference area as instructed by textbooks (e.g., Anderson). These results tell us that the F-104 has 2.5 more parasite drag than the B-58. You can arrive at these (unexpected) results by comparing aircraft of very different wing areas. The source for checking this can be your choice. Suggested source: NASA SP-468, p. 491 and 494, respectively. Thanks for reading. Philburgers (talk) 15:38, 31 August 2024 (UTC)[reply]

Hi, please note that this talk page is for noting improvements to or problems with the article, it is not a forum or reference desk (WP:NOTFORUM - WP:REFERENCEDESK). Nimbus (Cumulus nimbus floats by) 16:37, 31 August 2024 (UTC)[reply]

Philburgers I have read your comments with interest but I’m not yet persuaded there is a problem. I suggest you read Drag coefficient and Drag equation because it is likely that your comments might be more relevant to the material provided in one of these two articles.

Don’t forget that encyclopaedias, including Wikipedia, publish information from reliable published sources, even if we prefer different information to be provided. John Anderson is a reliable published source so we don’t hesitate to base certain statements on what Anderson has written even if opposing views exist in other sources. See WP:VERIFY.

If you believe some published authors are wrong, the best course of action is to communicate directly with these authors. It is not the role of an encyclopaedia to help work out which of two opposing views is the correct one. Dolphin (t) 10:29, 1 September 2024 (UTC)[reply]

Dear Dolphin,I understand you are an aeronautical engineer. If you did actually compare both CD0 of a F-104 and a B-58, and you are still not persuaded there is a problem, then.... there is not a problem. Philburgers (talk) 16:13, 1 September 2024 (UTC)[reply]

I don’t have access to the zero-lift drag coefficient so I haven’t actually compared them. You have told us that they are significantly different. Is your comment confined to these two aircraft? Surely it is true that drag coefficients vary significantly between all aircraft types.

The purpose of the zero-lift drag coefficient is not for comparison with other aircraft designs. It is very useful for analysing the drag on the aircraft across the full envelope of weight, airspeed and altitude, but only for aircraft of the type for which the drag coefficient was determined. Extrapolating to another aircraft type would be a misuse of the concept of drag coefficient.

The drag coefficient of any object, including an aircraft, can be based on any reference area so long as it is specified - diameter squared, frontal area, planform area, total surface area, net wing area, gross wing area, wetted wing area etc. None of these is perfect, but none is foolish either. The fact that none is perfect tells us that there will be anomalies if we compare the drag coefficients of two different object shapes. The best way to avoid these anomalies is to determine a unique drag coefficient for the object we are interested in, and not get distracted by the drag coefficients of other objects. If you wish to continue this discussion I’m happy to do so but please start a new thread on my Talk page. Dolphin (t) 22:28, 1 September 2024 (UTC)[reply]