Downwash question
Thread Starter
Join Date: Jan 2010
Location: UK
Posts: 5
Downwash question
Can anybody tell me if there would be any rotor downwash from a pair of stationary Apaches. They were waiting at the threshold, as i came in to land in a PA28, there was a strong wind blowing in the direction from the Apache's towards my landing point, and i experienced turbulence and windshear. I'm not sure if this would be due to the Apaches, or just the strong wind conditions, any thoughts would be greatly appreciated.
Join Date: Sep 2002
Location: Australia
Posts: 1,082
Not necessarily downwash, but turbulence, yes.
Anything upwind, such as a tree or building will give you turbulence.
Wind turbines are well known for their turbulence and they are deriving thrust, not imparting it.
And don't overlook short finals/ flare/ float is the most vulnerable phase of flight.
Anything upwind, such as a tree or building will give you turbulence.
Wind turbines are well known for their turbulence and they are deriving thrust, not imparting it.
And don't overlook short finals/ flare/ float is the most vulnerable phase of flight.
Join Date: Apr 2000
Location: EGDC
Posts: 8,351
A 200' wind turbine side on isn't the same as a 60' rotor edge on and a helicopter that is designed to fly through the air with a minimum of drag is unlikely to generate a great deal of turbulence when at flat pitch on the ground.
Join Date: Jan 2001
Location: Galway
Posts: 71
Originally Posted by Flying Bull
Well,
even if the collective is flat pitch - if one of the pilots is lazy on the pedals, the tail rotor can produce quite a bit of wind.
I blew a (rotten) wooden fence with the power of a fenestron ;-)
even if the collective is flat pitch - if one of the pilots is lazy on the pedals, the tail rotor can produce quite a bit of wind.
I blew a (rotten) wooden fence with the power of a fenestron ;-)
Join Date: Aug 2009
Location: australia
Age: 57
Posts: 43
Originally Posted by Flying Bull
Well,
even if the collective is flat pitch - if one of the pilots is lazy on the pedals, the tail rotor can produce quite a bit of wind.
I blew a (rotten) wooden fence with the power of a fenestron ;-)
even if the collective is flat pitch - if one of the pilots is lazy on the pedals, the tail rotor can produce quite a bit of wind.
I blew a (rotten) wooden fence with the power of a fenestron ;-)
Join Date: Feb 2006
Location: Germany
Posts: 876
Originally Posted by Davey Emcee
Presumably you were "lazy on the pedals" !!
@ rottenjohn - if someone stands on the brakes its a little bit different then normal - depending on the pedal design and your seating position, you need to stretch the leg/toes to get proper braking action.
Assume it is at the holing point of a runway, you´re normally turning a little bit to reach that position - hence uneven braking/pedal position is a possibility
Join Date: Feb 2006
Location: Germany
Posts: 876
Originally Posted by [email protected]
But again, that is a rotor side on, doing what is designed for - producing thrust - not one edge on at flat pitch.
Have seen someone blown away passing to close to the tail - lucky for him, he was on the right side. Was an ground accident to happen....
Join Date: Oct 1999
Location: Nigeria
Age: 54
Posts: 4,816
Originally Posted by Flying Bull
The tail rotor produces thrust if you put pedal in, flat pitch on the collective or not.
Have seen someone blown away passing to close to the tail - lucky for him, he was on the right side. Was an ground accident to happen....
Have seen someone blown away passing to close to the tail - lucky for him, he was on the right side. Was an ground accident to happen....
in a Super Puma you can roll the aircraft on its side with too much right pedal!
Join Date: Feb 2006
Location: Germany
Posts: 876
Originally Posted by [email protected]
Quite. You blew away a fence because your TR was producing thrust - the OP was about turbulence from a MR at flat pitch
Not understanding all the factors - he assumes, it must have been downwash.
I just added another possibility - which might not spring into mind helicopter pilots operating smaler helicopters - but heavy "birds" ;-) ahh helicopters need a lot of anti torque - which is produced by the tail rotor.
Even a slight foot forward, which won´t move or turn the helicopter will produce quite a lot of wind from the big fan at the back.
Understandable now?
Join Date: Apr 2000
Location: EGDC
Posts: 8,351
Even a slight foot forward, which won´t move or turn the helicopter will produce quite a lot of wind from the big fan at the back.
Understandable now?
Understandable now?
Yes, a TR will produce thrust on the ground but in the scenario posted by the FW pilot - the turbulence he experienced would not have been due to the helicopters.
