[color=blue][i][b]Does that mean that you *are* saying that Va decreasing with decreasing weight is not about protecting the wing spar? Which is what I said in the very first post.[/b][/i][/color]

That's precisely what I am saying. The reduction in speed is related to maintaining the limit load factor at stall. However, that's not quite what you stated in your first post .. which was

[i]You said that Va was limited by the max force the wings could cope with. If that was true, Va would not decrease with decreased aircraft load[/i]

If anything, it appears that the only poster pushing the reducing weight and wing spar concern .. is your good self.

[color=blue][i][b]Which seems to say that Va decreasing with decreased weight is to protect the main spar of the wing.[/b][/i][/color]

Perhaps your techniques for comprehension of the written word differ from mine ?

[color=blue][i][b]I never said, and never implied, that I intended to exceed the design limits of the aircraft.[/b][/i][/color]

That's a relief .. it appeared to me that you had made a number of suggestions whereby the limit load factor might be exceeded ?
[color=blue][i][b]
The issue is what the textbook said about what Va was for.[/b][/i][/color]

As I don't have the text, I can only go on your first post ... which didn't appear to suggest that Bob's text said anything about reducing speeds ?

[color=blue][i][b]It is quite obvious that, as someone reading the basic text books, that I would use the term Va in the way that basic textbooks use it.[/b][/i][/color]

Again, I am not able to comment on what Bob's texts may say or not. However, now that you do know the definition, that problem might be resolved ?

[color=blue][i][b]So, I invite you to get all crystal clear and clarify your earlier comments. If you can[/b][/i][/color]

Perhaps you might assist by putting a series of simple, precise bullet point queries rather than your previous writing style ?. I'm not trying to be difficult .. this topic is rather important for the other training folk who might be reading the thread ... so it is important that it continue to some sort of conclusion.

[color=blue][i][b]Va does protect the wings because it defines the maximum force that the wings can cope with.[/b][/i][/color]

Va, for the typical situation, will look after the wing structure. However, that is not how it is defined which is what you are endeavouring to suggest ? Again, I draw your attention to what the speed definition is in 23.335.
[color=blue][i][b]
you might have managed to stay a bit calmer[/b][/i][/color]

Those who know me, know that I don't raise a sweat under even extreme provocation .. I am, I assure you, quite calm. That is, I might add, a commonly observed characteristic of most experienced airline pilot folk.

Andrew I have a problem with your demeanour on this forum,, you seem to be trolling for an argument with every post I understand that you wish to contest every point you don't understand, but you are pushing my patience with your tone
Please be a bit more respectful of people who are trying to help you

Hi Stuart,
Sorry if you think I am trolling.

Trolls do not admit when they are wrong. I was grateful for being given the opportunity to be wrong about landing configuration and full flaps. The textbook really was an improvement on the standard definitions because "full flap" is more precise than "landing configuration".

As for the thread in question, my original post is valid. Decreasing (the rough definition of) Va with decreasing speed is not to protect the wing spar. If you halve the weight of the airplane and use max elevator at the max-weight Va, you will pull 7 G, but you will not put extra stress on the wing. (The plane will probably break, but the main spar will not.)

John said he agrees with what I said, but objects to the wording. Things John has said about me include the following

• being a little silly
• not of much relevance
• you are getting a bit lost
• Why are you preoccupied
• your thesis is quite irrelevant
• you would be entering dangerous waters
• you in the area of illegal operation
• you are getting to a straw man argument
• your blinkers removed
• caused your confusion
• you to argue with the Bench should your ideas ever be tested in Court.
• Read what I said rather than what you wish to read
• it is a figment of your own imagination
• your techniques for comprehension of the written word differ from mine
• your previous writing style

... all that because I had the temerity to point out something quite true. I even came up with my own solution to the problem, namely:

Regarding your above comment, Andrew, Va does protect the wings because it defines the maximum force that the wings can cope with. However, your point is correct in that lowering Va with lower weights does not protect the wing, it just protects the rest of the aircraft. (BTW, strictly speaking, Va only applies to the max weight speed. The extrapolated weight that you call Va is not really Va.)"

It appears that the thread is doomed to a continual going around in circles.

Suffice it to say -

(a) Va is an engineering design limit and not really of direct relevance to the flying folk, albeit that it is declared as a limitation.

(b) the Industry, through the FAA, eventually realised that what the design engineering folk understood by Va had, for a long time, been somewhat modified in practice by the flying folk.

(c) as a consequence, at A/L 23-45 (July 1993), the FAA introduced a new concept, known as the maximum [b]operating[/b] manoeuvring speed which better matched the typical flying folk's understanding of what manoeuvring speed might be. The maximum value for Vo (and the minimum value for Va) is the gross weight clean stall intersection with the limit load factor .. ie as defined previously. Operating at, or below, Vo should cause the aircraft to stall for pitching manoeuvres prior to exceeding the limit load factor in most circumstances. The relevant caveat is that the weight/speed reduction consideration is met.

I was having a reread of this thread and it occurred to me that, while

(a) we were talking about the situation for a min Va certification, which possibly is typical for most light aircraft, and

(b) I had noted the introduction of the Vo to differentiate between the not-quite-correct flying community's understanding of Va and what can occur in the certification world ..

I hadn't really made a strong enough point of the fact that Va may be considerable higher than the min Va (where the wing will stall if you pull limit load).

It may be useful for folks to read the FAA's words in the following AC.

AC 23-19A [color=blue][i][b]( https://www.faa.gov/documentLibrary/.../AC_23-19A.pdf [/b][/i][/color]) has this to say -

[i][color=blue]48. What is the design maneuvering speed VA ?

a. The design maneuvering speed is a value chosen by the applicant. It may not be less than Vs√n and need not be greater than Vc, but it could be greater if the applicant chose the higher value. The loads resulting from full control surface deflections at VA are used to design the empennage and ailerons in Part 23, §§ 23.423, 23.441, and 23.455.

b.[b] VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed[/b]. Only if VA= Vs √n will the airplane stall in a nose-up pitching maneuver at, or near, limit load factor. For airplanes where VA>VS√n, the pilot would have to check the maneuver; otherwise the airplane would exceed the limit load factor.

c. Amendment 23-45 added the operating maneuvering speed, VO, in § 23.1507. VO is established not greater than VS√n, and it is a speed where the airplane will stall in a nose-up pitching maneuver before exceeding the airplane structural limits.[/color][/i]

(The "applicant" is the OEM).

My interpretation has always been that, for a light aircraft whose AFM/POH states that one can use (single) control input at Va, then that aircraft's design likely was based on min Va. If the AFM/POH doesn't make the statement then one probably needs to presume that the Va for design was higher than min Va and one shouldn't be pulling other than a checked pitching manoeuvre to keep the loads below limit. For new certifications you may see the Vo definition for which you should see the abrupt control statement.

Do be careful, though, there be dragons out there for the unwary.