Good tutorials by Tripp from the 87th VFW Stray Dogs
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Hey guys, Pika here from the 87th VFW Stray Dogs.
My buddy Tripp from our Fighter Wing has been posting some pretty cool BMS 4.33.1 tutorials.
I would like to encourage you to take a look. He’s an accomplished BMS and RL pilot.
I learn a lot every time I fly with him.
Here’s a sample on Descent Planning:
PikaThe new post is up!
He was having technical difficulties with You Tube -
Hey guys, Pika here from the 87th VFW Straydogs.
My buddy Tripp from our Fighter Wing has been posting some pretty cool BMS 4.33.1 tutorials.
I would like to encourage you to take a look. He’s an accomplished BMS and RL pilot.
I learn a lot every time I fly with him.
Here’s a sample on Descent Planning:
PikaAll good techniques. Another thing you can do if you don’t have the steerpoint diamond and need to know how many degrees nose low to put the FPM to lose X feet in Y miles:
- Imagine the distance traveled at the 10 degs. NL pitch bar
- Set the FPM at the altitude to distance ratio based on that 10 degs. NL
Sounds confusing right? Picture it like this:
I want to travel 40 miles and lose 10K’…
- I picture 40 miles at the 10 degs. NL pitch bar
- I imagine 10 as 1/4 of this which gives me 2.5 degs. NL
Another example:
I want to descend 8K’ in 12 miles…
- Imagine 12 miles at the 10 degs. NL bar
- Set where 8 would fall in relation to 12, so about 2/3; which gives me 6.7 degs. NL
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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?
Sent from TapaTalk
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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.
–-------------------------------------------------------
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.