Master Airscrew (Stealth) props-performance.

[twickers14]

There was a brief chat about this subject very recently and as a result I invested in a set of red ones. Very smart. One small observation and wonder if any one else has experienced this-stick movements responses (and I am quite soft on them) seemed to be a tad jerky. Not all the time but from hovering the drone seemed to take a millisecond to respond (presume nothing to do with the props) and then spring very energetically into action. Good flying conditions. Wonder whether this has anything to do with the extra span of the props and the slight inclination at the tips. It’s not a problem for me and as this was my first flight with them I’m sure I’ll get used to them. Any thoughts very welcome. PS reckon they are a little more quiet too.

 

[F00Man]

There was a brief chat about this subject very recently and as a result I invested in a set of red ones. Very smart. One small observation and wonder if any one else has experienced this-stick movements responses (and I am quite soft on them) seemed to be a tad jerky. Not all the time but from hovering the drone seemed to take a millisecond to respond (presume nothing to do with the props) and then spring very energetically into action. Good flying conditions. Wonder whether this has anything to do with the extra span of the props and the slight inclination at the tips. It’s not a problem for me and as this was my first flight with them I’m sure I’ll get used to them. Any thoughts very welcome. PS reckon they are a little more quiet too.

Hi @twickers14 , I too have purchased the props and agree they are slightly quieter but they look a lot better! I have never noticed the response issue but I will definitely be aware and check it out.

Thanks,

JVA

BTW - Used to live in East Anglia for almost 4 years....loved it!

 

[twickers14]

Hi @twickers14 , I too have purchased the props and agree they are slightly quieter but they look a lot better! I have never noticed the response issue but I will definitely be aware and check it out.

Thanks,

JVA

BTW - Used to live in East Anglia for almost 4 years....loved it!

You’re an honorary Brit with that length of domicile. Could have been me over the jerky response but as you say they are rather racy.

 

[Peterson]

I have used them for the past couple of years on my MP2. Sound wise slightly lower levels but that would be perception but did get about an extra minute and a half of battery life consistently. Other then that they performed as well or better then OEM.

 

[jphoto]

I realise this is an old thread, but I didn't want to start a new one.
I just got two sets of Airscrew Stealth props for my Mini 3 Pro, and before I changed to them, I made some actual audio measurements.

Here is what I used: I have a Phonic PAA, a calibrated real-time analyser. I calibrated a General Radio SPL meter calibrator, so it should be accurate to within +/-1dB. However, absolute accuracy isn't really important here, relative measurements are.

For spectrum analysis I captured the drone sound using a Tascam Portacapture 8X using its 32 bit floating-point system. The files were then analyzed using tools in Adobe Audition, specifically the Amplitude Statistics and Frequency Analysis functions.

The drone was flown to a known and repeatable position approximately 6.5' away from the measurement point. Both the SPL meter and recorder were positioned at the same distance, as close as possible to each other.

The SPL measurements are made using the A Weighting filter, typical for this type of noise measurement.

The standard props were tested first.

Here are the results.
Specific SPL (dBA)
Standard: 62.5
Airscrew: 59.9
Difference: 2.6dB
For reference, 1dB is generally accepted as the minimum change that any person can perceive. A 10dB change is perceived as a doubling or halving of "volume".

Detailed measurements, Adobe Audition. Note that these are relative only. The 0dB reference for all Audition tests is 0dBFS. The Audition measurements did not us the A-Weighting filter. Instead, a 75Hz, 24dB/octave high pass filter was used, as was a 12kHz, 24dB/octave low pass filter. No other filtering was done.
Average RMS:
Standard: -26.4
Airscrew: -30.9
Difference 4.5dB (Airscrew is lower)

Spectrum:
The Frequency Analysis tool in Audition permits plotting of FFT spectrum of more than one file. Both files were analyzed using a 4096 point FFT, and the display has been limited to 50Hz to 20kHz. The standard props are the light green trace, and the Airscrew props are the orange trace. See attached image.

Verdict: The Airscrew props offer a small improvement in noise level, with weighted noise showing a very modest 2.6dBA improvement, while the unweighted (band limited) RMS difference shows a higher 4.5dB difference likely due to the inclusing of more low frequency energy in the result.

One observation that will take more study: with the Airscrew props installed, the individualt prop motor speed seems to be more different from one motor to the other. This shows up in the fundamental pitch tone of the props. With the standard props they all seem to be fairly close in frequency, but with the Airscrew props several different frequencies are noted, which may indicate some variance in manufacturing tolerances. While the overall noise level is slightly lower, the multiple prop tones in a static hover are more annoying to me personally, negating any reduction in overal sound level.

Again...more study.