Talk:Parasitic drag

Drag vs parasitic drag

How is this different from drag (physics)? Is it aviation specific? Fresheneesz 07:25, 30 May 2006 (UTC)

Basically—this article has an aerodynamic focus. Axda0002 15:22, 19 June 2006 (UTC)

Drag

what about flow seperation? and how ths is created by viscosity which results in form drag? form drag would not come about were it not for viscosity, also there is no mention of lamina and terbulent flows and the lamina turbulent transition and reynolds number. and what exactly is interference drag? is it the adverse efect of two bodies being close to each other resulting in greater drag than the sum of the parts? previously unsigned comment by 132.244.246.25

interference drag is defined in the article, it comes about because of vortecies in the air (I don't know what "two bodies" you're refering to). I'm not very familiar with this subject tho, but I'm sure if you ask your questions more clearly, they'd be more likely to be answered. Fresheneesz 06:50, 10 September 2006 (UTC)

Fresheneesz, you are mistaking induced drag with interference drag, those are quite different forms of drag as one is caused by any object that generates lift and second is caused by having two objects close or intersecting one another and thus one objects airflow is being disrupted by others and vice versa. That's why summing separate values of drag force corresponding to separate parts of aircraft will always result in smaller total drag than is actually being produced in real world conditions — Preceding unsigned comment added by 94.244.104.199 (talk) 09:21, 17 May 2018 (UTC)

error in diagram

contains a significant error. The two components of total drag, Induced and Form, tend to zero at (respectively) infinite and zero airspeed. Consequently total drag asymptotically approaches Form Drag at high airspeed, and this is correctly shown. However conversely total drag should approach Induced Drag at zero airspeed and this is not shown. In fact at zero airspeed, total drag is shown as exceeding Induced Drag by almost as much as it does at the optimum glide ratio, even though form drag is zero. -- 202.63.39.58 (talk) 23:50, 5 March 2010 (UTC)

Don't forget that the form drag is only one of three components (form, interference and skin friction) of parasitic drag so you should use parasitic drag instead of form drag to achieve accurate cruise point of flight. Also you were correct about parasitic drag curve that it becomes zero when airspeed is zero, but everything was okay with induced drag curve as it was in hyperbola shape which actually tends to zero at infinity, no need to make it that obvious because you can't actually reach infinity now can you? :) 94.244.104.199 (talk) 09:46, 17 May 2018 (UTC)

I suggest the diagram be adjusted in a different way. It can currently be interpreted as indicating that the induced drag is infinite at zero velocity. That doesn't make sense, since drag would be zero at zero velocity. Then I realized that the induced drag curve is for constant lift, and one cannot obtain a given amount of lift below some velocity. I suggest the diagram should indicate that the curve really does stop. Maybe a second vertical dotted line labeled "stall speed"? Vanzandtj (talk) 12:59, 15 July 2021 (UTC)

Confusing introduction

I'm confused by the introduction of the article, which says that Parasitic drag (also called skin friction drag) and then goes on to say that Skin friction and interference drag are also major components of parasitic drag. This leaves me confused as to whether parasitic drag and skin friction drag are synonyms (implied by the first sentence), or whether skin friction drag is merely a component of parasitic drag. It may be that both of these are the case, but if so it would be helpful if the article stated this clearly; I hope that someone more knowledgeable in this subject sees this and can edit the article. 84.51.131.203 (talk) —Preceding undated comment added 15:51, 18 March 2011 (UTC).

The main graphic is wrong and it should be removed. The total drag is a combination of the "parasitic drag" and the induced drag.--Abuk SABUK (talk) 22:13, 23 October 2012 (UTC)

Profile drag

The definition of profile drag previously used seems to be incorrect, or at least unusual. I have updated it to define it as the sum of form drag and skin friction. This is the definition found in the dictionary sources I have checked and also in many aerodynamics texts.

However, I have come across its use as a synonym for form drag (eg in this article before my changes), so I have added a note to indicate that this definition is also seen.

If anyone with deeper knowledge feels that this latter use is just plain wrong then they might like to edit the article to indicate that such usage is an error. I feel that the article should still mention its use as a synonym for form drag, even if it then states that this use is incorrect.Jontyla (talk) 19:15, 23 January 2013 (UTC)

Profile drag is a synonym for the whole of parasitic drag. I've added a reference. (It's a bit confusing that "profile" would include "skin friction", but that's the way it is.) cagliost (talk) 16:36, 13 October 2021 (UTC)

skin friction drag

The skin friction drag chapter at the end sort of does mention form resistance. Does not seem right — Preceding unsigned comment added by 91.192.37.51 (talk) 10:37, 22 January 2015 (UTC)

Interference drag - is it just a type of form drag

The description of interference drag has no sources but makes it sound like a variety of form drag - Can we clarify &/or source ? - Rod57 (talk) 19:34, 7 May 2017 (UTC)

Hi Rod57, interference drag is in no way a variety of form drag it is rather a drag produced when airflow on one shape influences the airflow on other shape and vice versa when they're close enough or intersect each other 94.244.104.199 (talk) 09:28, 17 May 2018 (UTC)

Rod57: The inclusion of interference drag in this article is entirely misleading. I notice it is also entirely unsourced! The parasitic drag on a body is the form drag plus the skin friction drag. Interference drag is relevant when we observe the increase in total drag on two or more objects as those objects are brought closer together — the increase is explained as being interference drag.

In coming days I will work on a way to rationalise the article; probably by deleting the unsourced information about interference drag. Dolphin (t) 01:05, 19 May 2019 (UTC)

I have erased the information about interference drag. It was all unsourced, and it was inconsistent with many (most, all?) reliable sources. See my diff. Dolphin (t) 14:26, 21 May 2019 (UTC)

@Dolphin51: The article Interference drag was merged into this article back in 2006 on the assumption that it is a component of parasitic drag, and Interference drag redirects here. If you want to remove all reference to interference drag from this article, you will need to restore the article Interference drag or find another home for it to redirect to. Sparkie82 (t•c) 14:39, 31 May 2019 (UTC)

Valid comment! I will give it some serious thought and make some changes somewhere. Dolphin (t) 00:13, 1 June 2019 (UTC)

I have re-added information about interference drag, this time with sources. The only categories of aerodynamic drag are induced drag, wave drag, and parasitic drag. Interference drag is not a type of induced drag or wave drag, therefore is a type of parasitic drag, so it belongs in this article. Whether it belongs in the form drag section or in its own section is another question. I would say it is a type of form drag because it depends on the shape of the aircraft as a whole. An aircraft does not just consist of wings, it includes a fuselage, wheels and sometimes struts, etc. Biplanes are famous for their interference drag. cagliost (talk) 13:35, 13 October 2021 (UTC)

A comment above claims "The parasitic drag on a body is the form drag plus the skin friction drag." Clearly this is untrue, interference drag is a component of parasitic drag. The question is whether it is a type of form drag or needs its own section. I would say it is a type of form drag, since it depends on the shape (form) of the aircraft. cagliost (talk) 13:40, 13 October 2021 (UTC)

Turns out wave drag is a component of parasitic drag. I've updated the article with a reference. cagliost (talk) 16:16, 13 October 2021 (UTC)

Delete section: Profile drag and combine it with the introduction

The section 'profile drag' only says that profile drag is synonymous with parasitic drag. To avoid confusion and better search results in the web, consider deleting the section and restructuring the intro to accommodate the information.

Like: "Parasitic Drag also referred to as Profile drag"....

Redirection from 'Profile Drag' can also be an addition. Icestorm6 (talk) 07:42, 15 January 2020 (UTC)

@Icestorm6: I don't agree that the section should be deleted. I have supplied some better information - see my diff. I hope to supply a little more information within the next day or two. Dolphin (t) 11:22, 16 January 2020 (UTC)

Fixed. Profile drag is just another name of parasitic drag. I have added a reference. cagliost (talk) 16:17, 13 October 2021 (UTC)

Wave drag belonging where?

In the Overview section of Wave drag, it says that wave drag presents itself as part of pressure drag. This article states that pressure drag is part of parasitic drag but then states that wave drag is not part of parasitic drag. Can someone reconcile this? — kashmīrī ^TALK 06:46, 10 August 2020 (UTC)

Fixed. cagliost (talk) 16:17, 13 October 2021 (UTC)

As the speed increases... parasitic drag increases because the fluid is striking the object with greater force...

This appears in "Description". Is it correct? If so, what is the explanation? Thanks Pieter1963 (talk) 23:15, 26 July 2021 (UTC)

The entire paragraph is amateurish! The sentence you have quoted is particularly amateurish. It presents an incorrect explanation of parasitic drag. I will attempt a wholesale rewrite of the paragraph in the next day or two.

In a nutshell, parasitic drag has two components - skin-friction drag and form drag. The two are very different and each deserves its own explanation. Dolphin (t) 23:07, 27 July 2021 (UTC)

I have edited the lead and deleted the section titled "Description" - it was unsourced, amateurish and unnecessary. See the diff. In coming days I will do some work on the sections titled "Skin-friction drag" and "Form drag" to add anything of value that was deleted when I erased "Description". Dolphin (t) 13:18, 28 July 2021 (UTC)