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Camera mounted on "Spinner"

AX-O

Well Known Member
I was asked on a different post regarding a picture of a prop in flight.

When Dilemma was configured with a fixed pitch prop, I was doing a lot of testing for Catto propellers. Craig was experimenting with different blade shapes and fences. in the process of that we were tufting the airflow real time and recording it with a video camera mounted on a modified crush plate. We also used a mixture of engine oil and baby powder (that made a mess). pics below.
 

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I remember seeing those pictures and videos when Craig was doing those tests, and loved the originality and creativity of mounting a camera on the hub!

Do you remember if you had any cooling issues (or improvements?) without the spinner helping the airflow at the inlets, or were the flights short enough that it didn’t matter?
 
Do you remember if you had any cooling issues (or improvements?) without the spinner helping the airflow at the inlets, or were the flights short enough that it didn’t matter?

I also did testing without a spinner. Just the prop and the crush plate. If I remember correctly the cylinder front CHTs went up 8-10 deg (depending on oat) but the rear cylinders were unchanged. There was no measurable impact on airspeed.

The inboard portion of the cowl inlet has reverse flow in some cases. Not having the spinner on definitely affected that area.
 
Tufts

With tufts on the propeller, how does one separate the centrifugal force from the airstream? I would think one would need a tuft with the same density as the air; or just fly thru a smoke cloud....
 
Probably confidential, but did you learn anything from doing this? Did you balance everything before flying? What kind of camera?

I think someone would make some money creating tough, tiny cameras that could be used anywhere to record what's happening, and then include the software to pull everything together with the telemetry to analyze what happened. I'm guessing this would be interesting for aviation, and all kinds of "action" sports.
 
With tufts on the propeller, how does one separate the centrifugal force from the airstream? I would think one would need a tuft with the same density as the air; or just fly thru a smoke cloud....

Without doing the math, and given the low mass of a tuft of yarn, I suspect that the centrifugal force is small enough to ignore (relative to the forces imparted by airflow).
 
What is learned would be interesting on what is obvious but new to a novice and the proprietary.

It sure looks like some onboard tufts standing at 90 deg to the surface, maybe an optical declusion though.
 
With tufts on the propeller, how does one separate the centrifugal force from the airstream? I would think one would need a tuft with the same density as the air; or just fly thru a smoke cloud....
Although what we see may not be perfect because of complexities, before anyone saw these pics, the conversations regarding airflow around the prop were mostly theory. Now we have pictures of actual data. The data may not be 100% accurate, however this data plus theory will get us further.

did you learn anything from doing this? Did you balance everything before flying? What kind of camera?

They used that data as well as quantitative data to affect other blade designs. No additional balancing was done. The camera was at the center of rotation. I was not able to perceive any difference. The camera was a GoPro.

Some additional info. Since this prop is fixed pitch, the angle of attack of the blades is controlled by the RPM, airspeed and aircraft angle of attack. So, the flight cards have a lot of different conditions. Ranging from idle to max RPM.
 
How many wraps of the power cord did you get before you had to shut down again?

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