Transverse Flow Effect in hot weather

[zerek]

On a hot sunny day, will you have to compensate more for your transverse flow effect than on a chilly day?
Thinking about updrafts from heated surfaces.
For example, your over an black surface, (taxiway, runway or similar) and want to do an takeoff. When you hit about 10-15knots you will have to give more forward-right cyclic input than normal.


zerek,

[Skiddz]

Transverse flow is not related to thermal activity. It's very much like disymmetry of lift, but in the pitch axis and has to do with airflow down through the rotor disc in forward flight.

In full scale, you add more forward cyclic to make sure you fly an appropriate takeoff profile. You want to build airspeed before beginning your climbout. Translational lift (not transverse flow) will make the helicopter want to climb, so you add forward cyclic to get airpseed to 50 knots or so before you begin the climb out.

Hot day will require a bit more power just because it's hot. Air is less dense which means less "bite" from the rotor blades and less power from the engine. Conversely, cold air will give you more performance because of its higher density.

[TheBum]

Forgive my ignorance, but can someone explain what you're talking about in layman's terms?

[zerek]

Forgive my ignorance, but can someone explain what you're talking about in layman's terms?

^^ that was for me or Skiddz?

Transverse flow is not related to thermal activity. It's very much like disymmetry of lift, but in the pitch axis and has to do with airflow down through the rotor disc in forward flight.

In full scale, you add more forward cyclic to make sure you fly an appropriate takeoff profile. You want to build airspeed before beginning your climbout. Translational lift (not transverse flow) will make the helicopter want to climb, so you add forward cyclic to get airpseed to 50 knots or so before you begin the climb out.

Hot day will require a bit more power just because it's hot. Air is less dense which means less "bite" from the rotor blades and less power from the engine. Conversely, cold air will give you more performance because of its higher density.

Thanks for reply, bit cryptic, but think i understand :YeaBaby:

So basically, your control input on the cyclic would be exact the same wherever if it's hot air, cold air, updrafts or downdrafts (except turbulence).

Also, in hot weather when higher power settings are needed. Will the change of "lift vectors" be larger when entering ETL?

[TheBum]

^^ that was for me or Skiddz?
You. This is the first reference I've seen to "Transverse Flow Effect". Being the inquisitive and technical guy that I am, my interest is piqued.

[Skiddz]

This is a pretty simplified explanation:

http://www.dynamicflight.com/aerodynamics/transverse_flow_eff/

[zerek]

:thumbup: love google.