Good tutorials by Tripp from the 87th VFW Stray Dogs
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If you like maths, its altitude change (100ft) divided by the distance (nm)
So if your at 20K and want to be at 5K at 45nm…20000-5000 = 15000 altitude (difference)
15000ft / 45nm = 3.3 degrees flight path angle
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Simple trigonometry IIRC as finding the angle of a triangle? The difference of 2 sides divided by the third base side. Wow flash back from high school?
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Simple trigonometry IIRC as finding the angle of a triangle? The difference of 2 sides divided by the third base side. Wow flash back from high school?
Sent from TapaTalk
Could you provide an example ?
My maths is a bit rusty.
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The link is not working. It says the video was removed.
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Lol mine are rustier. Just was a flashback.
Sent from TapaTalk
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The link is not working. It says the video was removed.
Seems like the whole channel has been deleted. Shame as I was looking forward to more tutorials.
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Here it is,
Sorry for the delay
Pika -
Seems like the whole channel has been deleted. Shame as I was looking forward to more tutorials.
Here it is,
Sorry for the delay
Pika -
Simple trigonometry IIRC as finding the angle of a triangle? The difference of 2 sides divided by the third base side. Wow flash back from high school?
Sent from TapaTalk
Math applicable Only for small angles, as in this case you have the approximation sin(alpha) ~ (alpha)
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Another possibility. Takes a bit more calculation, but instead of pitch, you can also use rate of descent and 1-in-60-rule as a good enough approximation.
What’s the 1-in-60-rule?
Your ground speed (knots) is the distance (NM) you travel in 1 hour. Divide that by 60, and you get your distance travelled in minutes.
E.g. 360 knots GS = 360 NM / hour / 60 = 6NM / minIn the International Standard Atmosphere (ISA), Mach number x 10 = NM / min. So Mach 0.60 = 6NM / min.
So in ISA, when you fly Mach 0.60, your ground speed is 360 knots, or 6NM / min. If you fly 420 knots, that’s Mach 0.70 or 7NM / min; 480 knots = Mach 0.80 = 8 NM / min and so on.
Now that we know that:
Imagine you’re at 22,000ft, Mach 0.80 (hence assume ground speed = 480kts), and you have 64NM to descend to 4,000ft.
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64NM / 480 knots = 64NM / 8NM/min = 8 minutes
22,000ft - 4,000ft = 18,000ft
18,000ft / 8 min = 2,250 ft/minSimilarly, imagine the same scenario, except you want to calculate the distance you need for a given rate of descent.
22,000ft - 4,000ft = 18,000ft
18,000ft / 4000ft / min = 4.5 min
4.5 min * (480 NM / hour / 60 min) = 4.5 min * 8 NM/min = 36NMThis method isn’t 100% accurate, because you assume your initial speed and speed will change during the descent, but it’s so good an approximation that it’s used every day by real ATC to know when to start descending aircraft at which rate.