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calculating lift co efficient using integration

Hi guys, i really need help with this. any advice would be appreciated.Screenshot 2024-03-07 215233.png
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Screenshot 2024-03-09 124122.pngScreenshot 2024-03-09 124354.png
(edited 9 months ago)
Reply 1
Original post by safwans67
Hi guys, i really need help with this. any advice would be appreciated.Screenshot 2024-03-07 215233.png
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It looks like uni coursework/assignment and with a bit of googling I can guess what the last two columns are and the length of the aerofoil and I can only presume the columns are measurements at different places, but Im really unsure? Id guess theyre asking you to integrate along the aerofoil length, but I could be way off. It almost goes without saying that you should post the full question and be clear about what you know/have been taught about calculating lift coefficients and what youre unsure about.

However, surely the easiest/best thing for you to do is to ask your tutor/lecturer for appropriate advice.
(edited 9 months ago)
Reply 2
Original post by mqb2766
It looks like uni coursework/assignment and with a bit of googling I can guess what the last two columns are and the length of the aerofoil and I can only presume the columns are measurements at different places, but Im really unsure? Id guess theyre asking you to integrate along the aerofoil length, but I could be way off. It almost goes without saying that you should post the full question and be clear about what you know/have been taught about calculating lift coefficients and what youre unsure about.
However, surely the easiest/best thing for you to do is to ask your tutor/lecturer for appropriate advice.
im just confused as to what the x will be?
Reply 3
Original post by safwans67
im just confused as to what the x will be?
As youve only posted the data without the question/description, its "impossible" to say.
(edited 9 months ago)
Reply 4
Original post by mqb2766
As youve only posted the data without the question/description, its "impossible" to say.
have a look now, hopefully should be clear now thanks.

im confused as to what Xn will be?
(edited 9 months ago)
Reply 5
Original post by safwans67
have a look now, hopefully should be clear now thanks.
im confused as to what Xn will be?
I know what the trapezoidal rule is, but youve not said what the columns in your data set are. As in #1, id guess youre doing the the trapezoid rule for each row (over the 14 columns) but as Ive no idea what they represent and how they relate to the lift coefficient. I could be very wrong.
(edited 9 months ago)
Reply 6
Original post by mqb2766
I know what the trapezoidal rule is, but youve not said what the columns in your data set are. As in #1, id guess youre doing the the trapezoid rule for each row (over the 14 columns) but as Ive no idea what they represent, I could be very wrong.
they are the heights of each point
Reply 7
so i have to calculate the lift co efficient of -4, 0, 8, 16 with and without the gurney flap.
Reply 8
Original post by safwans67
they are the heights of each point
Heights of what and how is one column related to the next and so on ...
Reply 9
Original post by mqb2766
Heights of what and how is one column related to the next and so on ...
Screenshot 2024-03-09 135512.png can you see the red rectangles? the height of these so we measured the height of each one 1,2,3 etc.

the angles of attack -4,0,8,16 we changed by turning a switch so the heights would change each time for the angles of attack, we then measured the heights.

Does that make sense?
(edited 9 months ago)
Reply 10
Original post by safwans67
Screenshot 2024-03-09 135512.png can you see the red rectangles? the height of these so we measured the height of each one 1,2,3 etc.
the angles of attack -4,0,8,16 we changed by turning a switch so the heights would change each time for the angles of attack, we then measured the heights.
Does that make sense?
Somewhat, but as per #1 Im presuming you numerically integrate these measurements using the trapezoid rule along "the length" of the aerofoil(?) (how are they arranged/displaced) to get some measure of total or average height/pressure/... and you then use xxx equation(s) that you must have in your notes to relate that to the lift coefficient. Im presuming you had some idea of why you were measuring the heights/pressures when you were recording them?

Tbh, Im feeling a bit of death by a thousand cuts trying to make much sense of what youve done / what youve been told.

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