Talk:Load factor (aeronautics)
|WikiProject Physics / Fluid Dynamics||(Rated Start-class, Low-importance)|
|WikiProject Aviation / Aircraft||(Rated Start-class)|
Claim of copyright violation
On 12 March 2008 the Introduction to Load factor (aerodynamics) was deleted on the grounds that it violated copyright in relation to the following website. It has been suggested that I might re-write the area that was deleted.
When Load factor (aerodynamics) was created on 21 May 2007 it appears to have been a copy of the text at the above website. On 21 August 2007 I significantly amended the article. (I think my amendments brought about an improvement. The amendments certainly moved the Introduction away from the text of the above website.)
On 12 March I restored the recently deleted Introduction. I would appreciate the views of others as to whether the Introduction still carries a risk of copyright violation, and whether the Introduction needs to be re-written. I would also appreciate ideas on what a new Introduction might look like. Dolphin51 (talk) 23:31, 12 March 2008 (UTC)
- Thanks for the note here. Let's proceed forward and clean up the article. I'll do some wiki work, but I cannot copyedit too much because the subject matter is out of my field. Keep up the good work, Kingturtle (talk) 02:39, 13 March 2008 (UTC)
weight or mass?
Hi again Kingturtle. I'm very happy to help polish this article. I will do some work on it in the next day or two. Yes, weight is correct here. Load factor is a ratio. More particularly, it is the ratio of two forces - the lift force acting on the aircraft and the weight of the aircraft. Consequently it is a dimensionless ratio - the number of G. If it were the ratio of lift to mass it would be an acceleration and have units such as metres per second squared. Dolphin51 (talk) 07:31, 13 March 2008 (UTC)
I've made a number of changes which I believe improve the quality of the article, in particular:
- Physical meaning of load factor added to opening sentence.
- Discussion on 1 g not being the same as 9.8 m/s2 made more prominent, given the confusion that there is around on this point.
- Discussion on the breakdown of lift among wing, fuselage and tailplane simplified (it belongs to the Lift article, rather than Load factor).
- Two-line section on negative g merged with the one above.
- Clean-up: bold, repetitions, non-breaking spaces etc.
- Most of "See also" links removed; they are only loosely related to the load factor, not more than dozens of other articles.
Hello Giuliopp. Thanks for taking an interest in this article. It was overdue for a good clean-up.
One of the remaining areas requiring clean-up is the claim that load factor is expressed as number of g. At present, the article says: The load factor is expressed in units called g. However, the article also says Since the load factor is the ratio of two forces, it is dimensionless. The two statements are inconsistent and Wikipedia should state one or the other, but not both.
In the USA Federal Aviation Regulations, FAR 1, Load factor is defined as the ratio of a specified load to the total weight of the aircraft. No mention is made of g or units of measurement.
In the details within the Federal Aviation Regulations, limitations on load factor are specified but, again, no mention is made of g or units of measurement. See the following:
When an aircraft is turning with 60 degrees bank we say it is a 2g maneuver. It is tempting to say the load factor on this aircraft is also 2g but that is incorrect. If the aircraft is upright the load factor is plus two, but if it is inverted it is minus two. The expression 2g applied to a maneuver is almost universal but it is only colloquial because the aircraft is not accelerating at 19.6 m/s.
Load factor is the ratio of two forces. I suggest the way to clean up this aspect of the article is to delete all mention of load factor being expressed in units, or in multiples of g. Dolphin51 (talk) 02:59, 12 March 2010 (UTC)
- Hi Dolphin51,
- to delete all mentions of load factor being expressed in g seems rather draconian to me. Apart from strict FAA's official documents, the use of g units is so widespread in aeronautics that I think this article ought to reflect it somehow. Otherwise, after reading the article, the uninitiated reader would be left wondering what these g everybody's talking about are then.
- With regard to the meaning of g: granted, an aircraft pulling a +2 g turn is not accelerating at 19.6 m/s2, but an observer on board the aircraft would experience an apparent acceleration of gravity literally equal to 2·g i.e. twice the standard gravity. That's where the use of g units comes from, so it's not purely a colloquialism but it does make sense, in a way (a rather ambiguous way, admittedly).
- A few examples of authors using g: 1 from Stanford Uni, mentioning "the 1-g stall speed"; 2 from RA-Aus (although it improperly calls the load factor "wing loading"); 3 from Answers.com.
- I'm going to expand the article on this point, also to clarify the apparent contradiction g units/dimensionless.
- Giuliopp (talk) 00:28, 13 March 2010 (UTC)
- An acceptable compromise might be to have the lead sections of the article dedicated to load factor, defining it as the ratio of two forces and therefore dimensionless, noting that LF can be positive or negative, and citing the USA Federal Aviation Regulations (and EASA Certification Standards if you can find them). Then have one or more subsequent sections dedicated to the concept of maneuvering an aircraft, and explaining the common terminology in terms of 'g'. Then explaining that a n.g maneuver involves a load factor of n (or minus n if inverted). You have found some weblinks that could be used as in-line citations for the sections devoted to maneuvering. Dolphin51 (talk) 06:05, 13 March 2010 (UTC)
I like your latest changes. You are moving in a good direction. I have made a few changes, working to the principle that if the text is talking about a load factor it is a number not accompanied by g; but if the text is talking about a maneuver it is a number followed by g.
In Aerodynamics, Laurie Clancy summarises it very well in Section 14.3 "... a manoeuvre in which the load factor is n is often referred to as an ng manoeuvre, and n is sometimes loosely called the number of g's in the manoeuvre." Dolphin51 (talk) 10:43, 15 March 2010 (UTC)
- Thanks, I fully subscribe to the usage rule you laid down. To put it in other words, whenever in the sentence the term load factor is used, then only figures should appear, which is formally correct and still unambiguous (as in "a maximum load factor of 4"). If the term load factor is not used (talking about manoeuvres or even straight flight), then g can be used instead, as in "pulling a 2 g turn" (in fact it must be used, otherwise the sentence would lose its meaning). I'm going to mention this in the article, citing the reference you found. Giuliopp (talk) 23:55, 15 March 2010 (UTC)
Aerodynamics → aeronautics
Considering that the load factor discussed in this article
- involves in its definition the aircraft's weight, which is outside the scope of aerodynamics
- is a concern more from the point of view of the structure of an aircraft, rather than its aerodynamic properties
- Aerodynamics is a sub-set of fluid dynamics, and I agree that load factor has little to do with either. Let's change the title to something other than (aerodynamics). I have no objection to (aeronautics). Dolphin51 (talk) 22:45, 25 March 2010 (UTC)