Principles of Flight questions.
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Thanks for good explanation.
I was a little bit confused about 1,8 Vs and 2Vs and I figured out 2 possibilities.
1) assuming that Vs is constant and our airplane decelerated
2) assuming that Vs itself increased due to increased load factor and airplane was flying the same speeds but Vs before gust and after gust was different.
But so far I think that your explanation is good and easy. I just wanna confirm: are you 100% sure that your way is a proper JAA way to solve that kind of questions?
I was a little bit confused about 1,8 Vs and 2Vs and I figured out 2 possibilities.
1) assuming that Vs is constant and our airplane decelerated
2) assuming that Vs itself increased due to increased load factor and airplane was flying the same speeds but Vs before gust and after gust was different.
But so far I think that your explanation is good and easy. I just wanna confirm: are you 100% sure that your way is a proper JAA way to solve that kind of questions?
In your question you stated the following.
This clearly means that the airspeed decreased from 2Vs to 1.8Vs.
There is nothing in this wording to suggest that VS has increased.
The solution method used in previous post is the correct one for the question as stated in your post.
But if you wish to look at it from the point of view of an upgust increasing load factor and hence increasing stall speed then we can do so.
Stalling speed is proportional to the square root of the load factor.
If our speed remained constant and Vs increased such that our constant speed which was originally 2Vs then became 1.8 Vs, then Vs has changed from 1/2 our speed to 1/1.8 of our speed.
This means that VS increased by a factor of (1/1.8) / (1/2) which is 1.11.
So we have an 11% increase in Vs caused by our increase in Vs.
Vs is proportional to the square root of load factor, so for Vs to increase by a factor fo 1.11 the load factor must have increased by the square of 1.11 which is 1.23.
So our load factor has increasd by 23%.
I do not believe that this is the way in which the examiner intended the question to be interpreted, but it is of course possible.
Did the question offer the options "decrease by 19%" and also "increase by 23%"? If it did then you could appeal.
In reallity the whole thing would be more complicated because both the airspeed and the load factor would change simultaneously. But solving that type of problem is beyond the level of JAR ATPL questions.
You expirience a rapid gust which slow you down to 1.8Vs.
There is nothing in this wording to suggest that VS has increased.
The solution method used in previous post is the correct one for the question as stated in your post.
But if you wish to look at it from the point of view of an upgust increasing load factor and hence increasing stall speed then we can do so.
Stalling speed is proportional to the square root of the load factor.
If our speed remained constant and Vs increased such that our constant speed which was originally 2Vs then became 1.8 Vs, then Vs has changed from 1/2 our speed to 1/1.8 of our speed.
This means that VS increased by a factor of (1/1.8) / (1/2) which is 1.11.
So we have an 11% increase in Vs caused by our increase in Vs.
Vs is proportional to the square root of load factor, so for Vs to increase by a factor fo 1.11 the load factor must have increased by the square of 1.11 which is 1.23.
So our load factor has increasd by 23%.
I do not believe that this is the way in which the examiner intended the question to be interpreted, but it is of course possible.
Did the question offer the options "decrease by 19%" and also "increase by 23%"? If it did then you could appeal.
In reallity the whole thing would be more complicated because both the airspeed and the load factor would change simultaneously. But solving that type of problem is beyond the level of JAR ATPL questions.
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Thank you for a great explanation! I need to buy you a six-pack of beer 
I don't know what options were in the question because my friend told me that he had such question on the JAA exam. He didn't know how to figure out any answer. I'm going tomorrow for my exam so I just wanted to be prepared for all possibilities.
I don't know what options were in the question because my friend told me that he had such question on the JAA exam. He didn't know how to figure out any answer. I'm going tomorrow for my exam so I just wanted to be prepared for all possibilities.
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The closest exam question I can find to this is:
Q. An aeroplane maintains straight and level flight at a speed of 2 * VS. If a vertical gust causes a load factor of 2, the load factor n caused by the same gust at a speed of 1.3 VS would be:
(A) n = 1.65.
(B) n = 1.69.
(C) n = 4.
(D) n = 1.3.
Q. An aeroplane maintains straight and level flight at a speed of 2 * VS. If a vertical gust causes a load factor of 2, the load factor n caused by the same gust at a speed of 1.3 VS would be:
(A) n = 1.65.
(B) n = 1.69.
(C) n = 4.
(D) n = 1.3.
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Aye and thats just what your thinking when your appproaching the hold at rosun and it starts bouncing you around.
O that feels like 2g I wonder what its going to feel like when we slow down to 1.3Vs on approach. H'mm let me guess bumpy as
I do wonder if some of this theory is just to fill out someones ego because even if you do know it there is not alot you can do about it as a pilot. Yes a design engineer needs to know it and apply it, but a pilot?
O that feels like 2g I wonder what its going to feel like when we slow down to 1.3Vs on approach. H'mm let me guess bumpy as
I do wonder if some of this theory is just to fill out someones ego because even if you do know it there is not alot you can do about it as a pilot. Yes a design engineer needs to know it and apply it, but a pilot?
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mad_jock I completely agree with you! But I just want to pass that f**ing exams. I've got FAA CPL, IR, ME and I'm so pissed off about JAA way to exam pilots. In USA questions at the exam are from the pilot's life and quite easy to understand. In Europe you have to be an aeronautical engineer, aviation medicine doctor, lawyer and dispatcher to be a pilot. And spend almost a year just to pass ATPL exams.
I couldn't find an exact copy of it either Alex, although I did find the one that you have quoted. But that does not mean that such a question connot possibly have been added recently by an authority somewhere.
The important thing of course is that exam candidates understand how to tackle these questions in whatever from they may appear.
The important thing of course is that exam candidates understand how to tackle these questions in whatever from they may appear.
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Nah its not that bad flyer. After working with yank pilots I would say that there isn't quite enough theory in there system but would also agree that the JAR system has a bit more than required. I prefer have to much than to little. Anyway you should have been doing it back in 2000 when the feedback questions wern't quite as mature as they are now.
And the JAR method is spreading around the world displacing the FAA. It will stand you in good stead for the rest of your career.
BTW I find that I do use it, its just that its taken a few years for me to realise why we need some of it. Although Polar coordinates are still a load of bollocks.
And the JAR method is spreading around the world displacing the FAA. It will stand you in good stead for the rest of your career.
BTW I find that I do use it, its just that its taken a few years for me to realise why we need some of it. Although Polar coordinates are still a load of bollocks.
