Systems Jar exam yesterday
Joined: May 1999
Posts: 1,846
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From: Bristol, England
This really shouldn't be about exam technique. The exam questions should be clear and unambiguous with one correct answer and three wrong ones.
The CAA are quite onside about this and they regularly edit out bad questions and adjust the marks as a result of appeals from both candidates and schools. We'll bounce it up to them and see what they say.
The CAA are quite onside about this and they regularly edit out bad questions and adjust the marks as a result of appeals from both candidates and schools. We'll bounce it up to them and see what they say.
Joined: Mar 2003
Aviation Qualifications: PPL
Posts: 225
Likes: 21
From: London, England
Dihedral?
Keith.Williams. wrote...
Keith, this option crossed my mind, however, I sat this exam and option b) simply said "Dihedral". Had it said "Geometric Dihedral" then it would have been worth considering.
I understood that "dihedral" describes anything that contributes to lateral stability (i.e. sweepback, geometric dihedral, the fin etc...). I ignored this option straight away as it was not descriptive enough. Was this a little rash?
BTW, I answered "vortices" for the same reasons as CAT 3C but I'm not at all confident about any of the exams I took on Monday so I could be wrong!
I'm rather surpised that most contributors have ignored the torsional effects of dihedral. Dihedral causes the wing tips to be higher than the wing roots
I understood that "dihedral" describes anything that contributes to lateral stability (i.e. sweepback, geometric dihedral, the fin etc...). I ignored this option straight away as it was not descriptive enough. Was this a little rash?
BTW, I answered "vortices" for the same reasons as CAT 3C but I'm not at all confident about any of the exams I took on Monday so I could be wrong!
Joined: Jun 2002
Posts: 340
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From: Saaaaaaffffhampton
Agree
Alex
I totally agree with you they should be clear and concise, but rarely has that been the case since JAR.
Theres the correct way and the JAA way, if i remember correctly isnt this supposed to be in the aerodynamics / principles of flight paper? and not the systems?
Argggghh all i can say is thank F--k i got mine outta the way
Ah well if someone finds out can they post it on here
Would be interesting
Good luck anyway guys hope it pans out
I totally agree with you they should be clear and concise, but rarely has that been the case since JAR.
Theres the correct way and the JAA way, if i remember correctly isnt this supposed to be in the aerodynamics / principles of flight paper? and not the systems?
Argggghh all i can say is thank F--k i got mine outta the way
Ah well if someone finds out can they post it on here
Would be interesting
Good luck anyway guys hope it pans out
Joined: Aug 2001
Posts: 775
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From: Dorset
NineEighteen,
I cannot agree with your definition of dihedral.
The term (lateral) dihedral is commonly abreviated to "dihedral". It refers to the situation in which the wings or tailplane are angled upwards from root to tip. Its principal purpose is to increase lateral stability.
The term "longitudinal dihedral" refers to the relationship between the angles of incidence of the wing and tailplane (or canard). This is one of the factors that contribute to longitudinal stability.
The term "dihedral effect" is commonly used to refer to the way in which wing sweep back increases lateral stability, making the aircraft behave as if it had a greater degree of dihedral.
The question referred to in this string has already been challenged by EPTA and CABAIR (CCAT). If other schools have also challenged it, then it is likley that it will be scrapped and the points awarded to all students who took the exam.
All of the FTOs will be informed of the results of all such challenges about two or three weeks after the exam.
I cannot agree with your definition of dihedral.
The term (lateral) dihedral is commonly abreviated to "dihedral". It refers to the situation in which the wings or tailplane are angled upwards from root to tip. Its principal purpose is to increase lateral stability.
The term "longitudinal dihedral" refers to the relationship between the angles of incidence of the wing and tailplane (or canard). This is one of the factors that contribute to longitudinal stability.
The term "dihedral effect" is commonly used to refer to the way in which wing sweep back increases lateral stability, making the aircraft behave as if it had a greater degree of dihedral.
The question referred to in this string has already been challenged by EPTA and CABAIR (CCAT). If other schools have also challenged it, then it is likley that it will be scrapped and the points awarded to all students who took the exam.
All of the FTOs will be informed of the results of all such challenges about two or three weeks after the exam.
Joined: Nov 2001
Posts: 334
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From: Worldwide
Keith, just a quick question then......SO lets say that if someone gets their results in a week and gets 74%, and a few wks down the line they scrap the quesiton and award the results to the folk having just sat the exam, is it true to say that in this case the guy that got 74% will now get a letter saying that he/she actually got 75% now as a result of scrapping a question?? Has this ever happened??
Joined: Feb 2002
Posts: 210
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From: Home
very bad question indeed!!
Went for dihedral myself basing my theories on the same as Keith!
Ahhhh well looks another resit!!
I have all the possible answers written down for this question at home and i will post the question as it was word for word in the exam!! includin the 4 options!
Went for dihedral myself basing my theories on the same as Keith!
Ahhhh well looks another resit!!
I have all the possible answers written down for this question at home and i will post the question as it was word for word in the exam!! includin the 4 options!
Joined: Aug 2001
Posts: 775
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From: Dorset
Britishguy,
There are essentially two ways in which questions can be challenged. The first is by the students making a comment on the scrap paper provided in the exam. The second is by the FTOs who have until the end of business on the Friday of the exam week, to register any problems reported to them by their students.
The reason for this tight timescale is to enable the examiners to consider, and decide upon all challenges before starting to mark the papers. So whatever mark you receive in your exam results takes account of all challenges lodged.
If a challenge is accepted as being valid, the question to which it refers is temporarily removed from the question bank and the marks are awarded to all students who took the exam. The subject question is then examined by the appropriate JAA committee at a later date. Defective questions are either scrapped or modified, before being reused.
The best way to deal with problem questions is to lodge a challenge at the end of the exam, then report the problem to your CGI. He can probably make a more reasoned argument which has a better chance of being accepted by the examiners.
There are essentially two ways in which questions can be challenged. The first is by the students making a comment on the scrap paper provided in the exam. The second is by the FTOs who have until the end of business on the Friday of the exam week, to register any problems reported to them by their students.
The reason for this tight timescale is to enable the examiners to consider, and decide upon all challenges before starting to mark the papers. So whatever mark you receive in your exam results takes account of all challenges lodged.
If a challenge is accepted as being valid, the question to which it refers is temporarily removed from the question bank and the marks are awarded to all students who took the exam. The subject question is then examined by the appropriate JAA committee at a later date. Defective questions are either scrapped or modified, before being reused.
The best way to deal with problem questions is to lodge a challenge at the end of the exam, then report the problem to your CGI. He can probably make a more reasoned argument which has a better chance of being accepted by the examiners.
Joined: Aug 2001
Posts: 775
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From: Dorset
Although the formal statements will take a while longer, I have heard that the challenge was accepted. So if you get a result of 74% you actually did rather worse. If you get 75% you are very very lucky! Having defective questions in your exam can sometimes be quite helpful, provided you get the message back to your FTO before the end of the exam week.
Joined: Nov 2001
Posts: 334
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From: Worldwide
Right, as the appeal was accepted, did they (the CAA) at least indicate what the actual answer was?? It would be intersting to know.
Just forgot to add-I'll second NineEighteen on that statement. Thanks for clarifying the odd question I've asked you Keith.
Just forgot to add-I'll second NineEighteen on that statement. Thanks for clarifying the odd question I've asked you Keith.
Joined: Feb 2002
Posts: 210
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From: Home
Keith,
Will we ALL be awarded an additional 2% for this question regardless as to which answers we put?? or will it only be awarded to the people who appealed and made notes on their exam paper??
I put dihedral but nobody seems to belive this would cause the torsion despite your previous post!
Will we ALL be awarded an additional 2% for this question regardless as to which answers we put?? or will it only be awarded to the people who appealed and made notes on their exam paper??
I put dihedral but nobody seems to belive this would cause the torsion despite your previous post!
Joined: May 1999
Posts: 1,846
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From: Bristol, England
According to the examiner, all the candidates will be credited with the marks for this question. He acknowledges the question is inherently unsafe and it will be referred back to the Subject Experts at the JAA.
Joined: Aug 2001
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From: Dorset
Rowley,
As stated by Alex, all students taking the exam will get the marks for this question.
Although I said that dihedral would tend to cause wing twist I do not believe that this is the option the examiners were looking for.
To assess any possible twisting effects we should imagine that we have made vertical chordwise cuts through the wing roots and fixed the wings back on using a single horizontal pin. Now imagine the effects of the drag at the tips of dihedral wings. The tips are higher than the horizontal pin, so the drag will tend to cause the wings to rotate leading upwards. The lift at the tips of swept back wings will have a similar effect, but tending to rotate the wings leading edge down. This is why swept back wings are less prone to divergence. As the lift bends them upwards it also twists the tips leading edge down, thereby reducing the lift at the tips. This reduces the bending effect, so the wings do not diverge.
But the degree of twisting is proportional to the amount by which the tips are above and behind the roots. Lots of aircraft have 20 degress or more of sweepback, but dihedral angle is usually only a few degrees. this coupled with the fact that lift is much greater than drag, means that the torsional effects of sweep back are much greater than those of dihedral.
As stated by Alex, all students taking the exam will get the marks for this question.
Although I said that dihedral would tend to cause wing twist I do not believe that this is the option the examiners were looking for.
To assess any possible twisting effects we should imagine that we have made vertical chordwise cuts through the wing roots and fixed the wings back on using a single horizontal pin. Now imagine the effects of the drag at the tips of dihedral wings. The tips are higher than the horizontal pin, so the drag will tend to cause the wings to rotate leading upwards. The lift at the tips of swept back wings will have a similar effect, but tending to rotate the wings leading edge down. This is why swept back wings are less prone to divergence. As the lift bends them upwards it also twists the tips leading edge down, thereby reducing the lift at the tips. This reduces the bending effect, so the wings do not diverge.
But the degree of twisting is proportional to the amount by which the tips are above and behind the roots. Lots of aircraft have 20 degress or more of sweepback, but dihedral angle is usually only a few degrees. this coupled with the fact that lift is much greater than drag, means that the torsional effects of sweep back are much greater than those of dihedral.
Joined: Feb 2002
Posts: 210
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From: Home
Have just been told by my school.........they are aware of an appeal against this question but they are unsure as to wether it has been accepted!!
Are you two receiving inside info (alex,Kieth)
I pray to God that you are right with this...........cos right now i could do with every mark i can get my hands on!!!
Are you two receiving inside info (alex,Kieth)
I pray to God that you are right with this...........cos right now i could do with every mark i can get my hands on!!!