How Much Power Is Available?

[ice time]

Suppose i'm flying a jet ranger in the mountains. I depart from a heli port at 2000' and climb as quickly as i can (assume very little fuel burn therefore the helicopter weight hasn't changed much). If i need 80% torque to hover at 2000' will i use 80% torque to hover at the same skid and wind conditions at 8000'. If not, how can i determine what i would pull, versus how much i have available?

[sharkbait]

I assume someone will post a "rule of thumb" for this but have you tried looking in the flight manual?

[4961]

I've spent the last several years flying out of Whister BC, heliport elev. about 2100 feet. The mountains around here are about 8 to 9000 feet. If I took off at 80% tq I would expect at 8000 feet to have to have my ducks in a serious row and the wind pegged, then things would still be at 100% tq. Every time.

[skullcap]

Depends upon the strength of wind coming off the butterfly wings.

 

Seriously, there is no real answer to your question other than experience and checking the FM using the max cont charts. You will find that the charts are really only good for starting a fire in a survival situation but they give a rough ballpark figure. Lots of rules of thumb, the one I use alot is if you have to hover oge then the load will have to be reduced 250 pounds. This is not meant to be used when setting up longline loads but used to determine how much weight to be offloaded to climb out of a hole or such. Another usedful one is that if you are hovering in light or nil wind a lower altitudes then your torque should be around 90% for max gross weight, torque at same weight in same conditions will go up 5 8% torque at higher altitudes. I believe the old kiowa has a chart which depicts the torque increase with alitude and temperatures.

 

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