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Old 07-11-2018, 12:25 AM   #33
FragBum
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Join Date: Jun 2016
Location: QLD, AUS.
Posts: 1,355
Cool

Quote:
Originally Posted by WildBillKelsoe View Post
sorry for taking long to answer. the chart is not accurate. I used it to convey that as you reduce your collective, you taper the reduction, not slice it. Meaning:

If in hover your % of collective is 100%, you drop down to 90% then immediately go back to 95%. This should "arrest" your descent or sink rate. But I am sure you already knew this. Like in hornet.
Roger get it now, I try to keep VSI as constant as I can by bleeding just enough collective as needed to regulate VSI in practice they are likely representative but understand that method.


One thing to note for landing the Mi8 even the KA 50 both are 10 ish tones of helicopter, is the fact that decent rate will increase significantly when you drop collective and the VSI is really showing the past not the exact present so it is very easy to fall through 3 meters per second rate.


I try to keep VSI around 2 to 3 metres per second whilst still in ETL (>100K) however below ETL (<60K) stick with 1 to 2 metres per second and err closer to the 1 meter per second till about 3 to 5 metres above ground then 0.5 meters per second or less. Ideally The Mi8 has enough power to vertically hover all day IGE.


There is good reasoning to keep the VSI low you only have limited power and limited energy stored in the rotor deplete either and you are stuffed. O/P try landing with one engine she becomes interesting I tend to halve or more those VSI rates.


Also depending on the input device your using for collective you might consider applying some curvature to expand the range of movement of input device to change of value. This will give a more fine input at the lower end of travel and avoid the sudden drop off onto the ground. I found that very useful when using the "slider" input on my old logitech joystick as collective.

Doing so doesn't really effect the top end/cruse that much either, it may make setting power for cruse a tad finicky but you have time to deal with it where as when landing you don't.

Anyway that's got me enthused to take the Mi8 out for some fun.
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