CFD simulations of GoPro attached to wing

[MV Aviation]

Hi everyone,

during the now quieter time of the year I used some resources of my office to investigate how a GoPro (or any other action cam) that is mounted to a wing, influences the flow field. Many pilots are afraid to mount a cam to their wings or other locations on the fuselage, because it may make the aircraft uncontrollable in some situations.

I summed it all up in a short video. Please let me know what experiences you had with outside mounted cams.

Thanks

 

[Oscar Avalle]

Extremely interesting. Thank you

[Hector]

Nicely done! I suspected as much but I had not seen a CFD simulation of a GoPro. Given the proliferation of these cameras in aviation it's nice to see someone taking a more scientific approach in determining the aerodynamic effects.


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[carusoam]

 

MV, nice work.  

Tell us about the simulator you have acces to...  the mathematics is using huge amounts of data points.

Air is a pretty complex fluid.  It is low density, low viscosity and compressible.  Generally tough to simulate.

There has been some concern as some cameras end up in some sensitive areas near control surfaces.

It would be disastrous if a camera were to cause an uncontrolled oscillation of a control surface. Mounts don't usually hold this tightly.

Real life situations.  For comparison use the simulator to show the effects of speed brakes.  Compare the accuracy of the sim to actual video of speed brakes in rain. Compare the speed brake dimensions to those of the camera.  Speed brakes are relatively small for the forces they generate.

There are more and less sensitive locations.  Some locations are less sensitive to airflow disturbances.  The fuselage being the least sensitive.  The low pressure side of a wing is the most sensitive.  Wing tips and tale top are a maelstrom of aerodynamics.

air speed will also play an important part of airflow... at low speed airflow separation earlier than expected because of a camera would be bad...

Last thing in my mind.  The amount of ice that builds on a wing is gigantic compared to some of these cameras.  Ice doesn't avoid control surfaces. It has a tendency to weigh a lot.

Great idea.  It would be nice to have data about camera size and locations that are best for use.  It would be fabulous to have mounting ideas that improve or streamline the cameras effects.

i'm surprised cameras aren't showing up in locations like where landing lights, nav lights and taxi lights currently occupy.

Last question, in your video...  the camera is mounted a top the tail.  There is motion that looks like the tale is twisting compared to the plane.  Or is that the camera causing this effect?

we learn so much from each video and the various mounting locations.

PP thoughts only, not an aerodynamicist...

Best regards,

-a-

[Hank]

Anthony, it looked to me like his camera is mounted atop the rudder, whose counterweight projects forward over the top of the vertical stab . . . So the twisting is from his feet on the pedals.

[MV Aviation]

2 hours ago, carusoam said:

Tell us about the simulator you have acces to...  the mathematics is using huge amounts of data points.

I was using my desktop computer at work. The 13Mil. cells were in an order that just works. We do have way bigger high performance cluster at our institute, but they weren't necessary for this project.

2 hours ago, carusoam said:

It would be disastrous if a camera were to cause an uncontrolled oscillation of a control surface. Mounts don't usually hold this tightly.

I was amazed by how quickly the turbulence dissipates behind the cam. It doesn't even reach the trailing edge of the wing. Thus, I suspect that even if the cam was mounted on the horizontal/vertical stabilizer, the effect on the control surfaces would be minimal.

2 hours ago, carusoam said:

air speed will also play an important part of airflow... at low speed airflow separation earlier than expected because of a camera would be bad...

The main flow velocity is 50m/s, which is roughly 100kts. By the way, the legend in the video is m/s as well. For comparison, I did the exact same simulation with an angel of attack of 15° to see whether the flow detaches from the wing earlier. This would have come close to traffic pattern operations (low and slow), where stalls and spins end up way more disastrous. But the flow did not detach, not even locally (see attachment).

2 hours ago, carusoam said:

Last thing in my mind.  The amount of ice that builds on a wing is gigantic compared to some of these cameras.  Ice doesn't avoid control surfaces. It has a tendency to weigh a lot.

True. But ice forms at least somewhat symmetrically and doesn't influence the flow field massively in the beginning. The cam is mounted to one wing only, which may cause asymmetric phenomena (spins) to occur more easily.

2 hours ago, carusoam said:

Great idea.  It would be nice to have data about camera size and locations that are best for use.  It would be fabulous to have mounting ideas that improve or streamline the cameras effects.

I figured that this position (underneath the wing) is the most commonly used and the most influential in regard to the control surfaces downstream. From the results I expect that wherever you mount the cam on your aircraft, the effect will always be local.

2 hours ago, carusoam said:

Last question, in your video...  the camera is mounted a top the tail.  There is motion that looks like the tale is twisting compared to the plane.  Or is that the camera causing this effect?

I'm not exactly sure what you mean. The cam is hanging down from the lower side of the wing. Both wing and cam are "rigid" in the simulation and cannot move. Any movement you see is the air.

 

Thanks for your thoughts,

Marco

[MV Aviation]

2 hours ago, carusoam said:

Last question, in your video...  the camera is mounted a top the tail.  There is motion that looks like the tale is twisting compared to the plane.  Or is that the camera causing this effect?

 

1 hour ago, Hank said:

Anthony, it looked to me like his camera is mounted atop the rudder, whose counterweight projects forward over the top of the vertical stab . . . So the twisting is from his feet on the pedals.

Now I see what you guys mean. Yah, the cam was mounted on the rudder. Hence, the camera is moving with the rudder due to its defelction. The bit you see in the bottom middle of the video is the top part of the vertical stab, which is not moving (relative to the aircraft).

[midlifeflyer]

I've been experimenting with a DIY tiedown mount and you video definitely  demonstrates the biggest issue I've had to deal with.

[carusoam]

MV, thanks for the answers and additional detail...

regarding ice...  it can build evenly.  It can also break free in chunks very unevenly.  This is a danger of ice building on a prop and shedding unevenly.  The vibration of imbalance can be quite strong.

1) tie-down rings are often left in the wings during flight.

2) simulation shows airflow /disturbance around the camera is local.

3) there is a lot of data indicating that a camera mounted on the tiedown location causes a minimal affect.

would you be able to show any advantage of the camera mount being longer or shorter to adjust it's distance away/closer from the wing?

very interesting work you have created.  The graphics of airflow around the wing is very interesting.

Thanks again.

Best regards,

-a-