What is the optimal glide speed range for Mi-8

[MR_BURNS2]

What is the optimal glide speed range, rate of descent, rotor RPM etc. for autorotation?

 

I saw people in tutorials doing it around 80 KPH, but i suppose it depends on weight, altitude weather cond. etc.?

 

I assume there will be a chart in the manual, but maybe someone can share his wisdom whilst we patiently wait.

[AlphaOneSix]

The airspeed that will result in the slowest rate of descent is about 110-115kph, depending on the weight of the aircraft (heavier=faster). This will result in a descent rate between 7m/s (at low weight) and 11m/s (at high weight).

 

For the shallowest angle of descent (i.e. most glide range), the best airspeed is about 155-160kph, depending on the weight of the aircraft (heavier=slower). This will result in a glide ratio between roughly 3.5:1 (e.g. 3.5km per 1000m of altitude, at high weight) and 4.5:1 (at low weight).

 

The flight manual calls for 100-120kph as a standard number to use during an autorotative descent. The main rotor rpm should not be allowed to fall below 80% at any time during the descent, nor rise above 100%. Optimally, the main rotor rpm should be kept between 93 and 95%, as this gives some cushion to prevent overspeeding the rotor, while also providing a lot of potential energy in the rotor system when it comes time to land.

 

Altitude and weather conditions are largely irrelevant, since airspeeds are based in indicated values, and you should try to land into the wind to reduce relative forward speed to a minimum at time of touchdown.

[MR_BURNS2]

Thank you very much!

[PilotMi8]

....For the shallowest angle of descent (i.e. most glide range), the best airspeed is about 155-160kph, ..

:thumbup: but bit clarification: best airspeed for maximum range descending at autorotation is 180 .. 190km/h (for Mi-8 )