Multi rotor wash area?

[mikrokopstar]

Hello

So I've been using this Mikrokopter ARF OktoXL along with some sensors for atmospheric profiling, specifically temperature, relative humidity, and atmospheric pressure. Apparently, the rotor wash disrupts the air so that my readings are not accurate. Does anyone know the volume of air, or radius from the center of the rotor, that a rotor contaminates during flight? Also, is there any way to avoid the wash by flying a certain pattern (forward or downward)?

Any information is appreciated! Thanks:encouragement:

Mikrokopstar

 

[Malik112099]

Depending on prop size, RPMs and wind conditions it can be hard to nail down exact prop wash area. Avoid low flights over the ground/objects and descending in general to stay out of the prop wash when taking readings from the sensors. You also run into a certain amount of interference from just hovering.

 

[mikrokopstar]

Avoid low flights over the ground/objects and descending in general to stay out of the prop wash when taking readings from the sensors.

I was thinking that if the sensors were mounted below the multi rotor then descending would be useful in moving the prop wash away

 

[Malik112099]

You are literally falling into the prop wash when descending.

 

[DucktileMedia]

Is this a serious question? You want to measure the atmosphere underneath a bunch of spinning props???? C'mon man.

 

[JoeBob]

Sensors above the MR would give a better result than below..

 

[mikrokopstar]

Is this a serious question? You want to measure the atmosphere underneath a bunch of spinning props???? C'mon man.

If you read my first post you would see that I am trying the measure the atmosphere outside of the prop wash. Please try to post something a little more insightful

 

[stevemaller]

Hello

So I've been using this Mikrokopter ARF OktoXL along with some sensors for atmospheric profiling, specifically temperature, relative humidity, and atmospheric pressure. Apparently, the rotor wash disrupts the air so that my readings are not accurate. Does anyone know the volume of air, or radius from the center of the rotor, that a rotor contaminates during flight? Also, is there any way to avoid the wash by flying a certain pattern (forward or downward)?

Any information is appreciated! Thanks:encouragement:

Mikrokopstar

I'd think you need to be outside the ring of your motors, which is hard. Maybe just a 1 meter aluminum boom of some sort (carefully balanced of course) might do it.

 

[Old Man]

Find and look at some videos of aircraft generating wake turbulence and wing tip vortices to obtain a visual reference of what you are dealing with. In those the airflow over the wing is what is causing the turbulence. A propeller is just another form of a wing, but a bit more aggressive. The shape of the propeller generates both high and low pressure areas, just as an aircraft wing does. The earlier suggestion to mount your sensors on a boom extending well outside the propeller arc is a good one.

 

[mikrokopstar]

Find and look at some videos of aircraft generating wake turbulence and wing tip vortices to obtain a visual reference of what you are dealing with.

I do like that idea; however, a visual reference would only be able to provide a qualitative determination of where the wash is. I plan on placing sensors on a shaft mounted below my rotor, outside the propeller arc and comparing the readings, noting the position of each sensor with reference to the center of my rotor. This should provide a quantitative determination of the wash area

 

[JoeBob]

There is a pretty big disturbance to the sides as the air that was pushed down recirculates:

Above looks to be the shortest route to undisturbed air.
(There's always the chance that this illustration ignored effects above.)