Bucket Speed in Helicopters

Welcome back! I'm Jacob and this video outlines Bucket Speed. It pulls information from a video of my previous videos like Types of Drag ( • Types of Drag in Helic... ), Crucial Speeds ( • Crucial Speeds Every H... ), and 3 Bank Accounts ( • The 3 Bank Accounts fo... ). So if you're interested in those click the attached links.
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So what is bucket speed? It is the airspeed where the greatest excess of unused power exists. Said another way, its the speed where I have the most extra available power if I need it. Its called bucket speed because the range of speeds resemble a "bucket" on a cruise chart. Cruise performance charts depict power to speed in a usable form for pilots to use. On the left side of the chart you typically see airspeed, from 0 knots to VH or the max airspeed number depicted. On the bottom is power in terms of torque percentage, from 0% to Max torque available (MTA). Then you'll see a curved line run through the chart. This line tells me how power and airspeed work. If I want to fly at a specific airspeed, it outlines the power required. These charts will vary based on gross weight, temperature, and altitude (pressure/density). But they all read the same way. This curved line is the total drag line. It's just simply turned on its side. Notice its highest power required when I'm slow and fast but declines in between.
So to calculate bucket speed we find the halfway point of our MTA. If its 100%, we use 50%. If you are in a dual engine helicopter or you consider planning off of transient torque limits you may use numbers like 55% or 60%. In either case, for bucket speed draw a vertical line at your 1/2 MTA line and read the chart. Depending on environmental and weight limits, I generally intersect the line twice, an upper and lower airspeed. This is my bucket. If you draw the line sideways it resembles a bucket. Let's say its 60 - 80 knots. Between these 2 speeds I have the greatest margin of unused power. The very bottom of the bucket is my Velocity Best Endurance (VBE)/Velocity Best Rate of Climb (VY) also known as Max Rate of Climb/Endurance airspeed. Let's say that is 70 knots for this example.
So how do you use this information? Well it is regarded alone of the safest airspeed ranges to be in. IT is above Effective Translational Lift (ETL) and VSSE (Velocity Safe Single Engine) so the rotor is efficient in terms of wing tip vortices and induced drag. It is a speed that is below VH so if you did encounter an engine failure, the rotor wouldn't decay so rapidly you wouldn't be able to react in time which makes it survivable. It has the least amount of total drag which generates the best fuel burn for maximum time aloft. Lastly, the speed range offers the biggest torque cushioning for aggressive maneuvers. That is, you are the least likely to over torque due to transient torque spikes and rapid rotor incoming because you have the biggest margin for error with the excess engine power. Its just an all around optimal airspeed for having plenty of options while flying. In terms of my 3 bank accounts video, it provides excellent balances in airspeed and power available bank accounts should an emergency arise in flight.
That wraps up the video. If you enjoyed this video and made it all the way to the end, comment with a "🪣" bucket emoji to let me know you watched all the way through. Make sure to also hit like and subscribe as well. Thanks for watching.
As always, I'm Jacob and this is Helicopter Lessons in 10 Minutes or Less. Safe flying.