Stealth Drone Propellers

In NY upstate I'm willing to help with no pay. I had mod a little the original props to make them quieter while flying low in the neighborhood . One time a punch of kids in bycicle follow the bird home for curiosity and I had to bring it right back any way because it was low in batt .... Well the kids were ok I just had to show them a little, I don't like to be rude to kids. But I found my self many times wishing for quieter props ... and yes Own feather it's a fantastic mecanical approach...
 
dehoffma said:
Sounds really cool. If you expand to a need in Southeastern Pennsylvania, I'd help, I'd do it for free, except for maybe an adult beverage or 3. I once was a small business owner and I also spent 13 years with Lockheed, I'm pretty savvy with test results and feedback. I'd love to help a small biz succeed. Let me know if there's anything I can do to help.
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...or Kansas...
 
pgm944 said:
Hi All -

My colleague and I are developing new rotors for drones to significantly quiet the noise coming from the drones we love to fly. He is a nautical engineer who develops propulsion units for high end ships and I am a plastics engineer who knows all sorts of manufacturing techniques for low and mass production.

I am looking for pro-sumer operators of DJI drones in the Southeast Massachusetts area to test fly our creations. This will involve both inside (sound box) flying as well as "real world" flying. Compensation will only be the state minimum hourly wages, plus unlimited stealth props for your drone. Perhaps food and an adult beverage can be provided.

Not sure the best way to contact me on this forum... I leave that to your creativity.
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Just returned from a production trip to Mongolia where I wanted to shoot aerials of a horseman herding animals.

The propeller noise was too loud and the animals kept running away.

I would love to use quieter ones.

I live in central California so I guess you can't use testers here?!

[email protected]
 
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Hope y'all decide to develop these for the Mavic - that li'l guy seems irresistible to birds and insects.
Having a different tonality and volume would go a long way to avoiding bird strikes I believe.
 
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Prop noise can be eliminated by installing a noise cancellation device on drone. So instead of hearing the sound of a drone, it may sound like a puff of wind which will be further canceled out by human brains. I did this study back in the 90's while working at NASA to reduce jet engine noises inside cabin of DC-9. Rear passengers complained about harmonic noises from engines. After designing noise cancellation system, problem solved. Just my .02
 
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Yes active cancellation is possible with fixed frequencies especially in enclosed volumes. Newer tech reduces the h/w to headphone size but again the quieted space is finite and aided by attenuation from the ear cups.
Not practical for outdoor free-space environments.

A snip from Physics Stack Exchange:

"When you allow sound to propagate into the surrounding space, you can no longer treat it as locally homogeneous oscillations: you have a source of waves which you're trying to cancel out by adding a phased-out source. You then have two wave sources, and these will interfere according to the usual rules of wave phenomena: you will have regions where their effects cancel out, and regions where they add up with each other to make a stronger (in fact, by a factor of 4) effect.

You can of course dream up fancier systems than just a single ANC source. However, they will all fall foul of this problem. The fundamental reason for this is, of course, conservation of energy. Your noise source is emitting energy into the environment. You are further using your ANC sources to put out even more energy into it. This energy has to end up somewhere - it can't just vanish. Wave interference simply causes a 're-routing' of energy from places where you want it to be quiet into places that necessarily will become louder."
 
IMG_1663.JPG
Example of stealth helicopter blades
 
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theTastyCat said:
Ah, the internet - somebody has a fresh idea or wants to explore something and strangers load criticism or disbelief right off the bat...keep on, OP - quieter props would benefit all of us.
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Yes, I agree. Once those props start to turn so do heads and EVERYONE looks and when they see the quad, they immediately think they are so important that you are spying on THEM! I always wonder about the reaction when I am examining the rear of a house and have to back up to get a larger perspective or avoid trees and must cross fence lines if someone will think I am 'spying' on them since they probably do not bother to look at where the camera is trained and I usually get a 360 anyway to orient my position in relation to other objects. I also wonder if anyone has been able to see inside a closed window during the day? I know I have tried just out of curiosity and cannot.
 
thx1138 said:
Prop noise can be eliminated by installing a noise cancellation device on drone. So instead of hearing the sound of a drone, it may sound like a puff of wind which will be further canceled out by human brains. I did this study back in the 90's while working at NASA to reduce jet engine noises inside cabin of DC-9. Rear passengers complained about harmonic noises from engines. After designing noise cancellation system, problem solved. Just my .02
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You'll see this tech in higher end refrigerators and other tings as well.
 
I think its a great idea. I think half the fear is from the noise. The Mavic is fairly quite compare to the others. I've had a few racers with carbon props that were very very quiet if you did not gun it.
 
I'm an operator in SWFL. That's not near Boston, but I'm keen to test your new product and could give you feedback and results.
Tim
23nine5threeSeven2fivesevenEight
 
The stealth helo is a good example of the engineering of the blade tips. At high rotor speeds the tips are moving at supersonic speeds. Shock waves are produced (basically small “sonic booms” are created which have to be minimized by the tip design to reduce noise. Our Phantoms prop tips aren’t moving quite that fast, but attention still has to be paid to it. DJI, etc. knows this too, but the EROI isn’t there. If noise effects sales though, that might be another story...
 
pgm944 said:
Hi All -

My colleague and I are developing new rotors for drones to significantly quiet the noise coming from the drones we love to fly. He is a nautical engineer who develops propulsion units for high end ships and I am a plastics engineer who knows all sorts of manufacturing techniques for low and mass production.

I am looking for pro-sumer operators of DJI drones in the Southeast Massachusetts area to test fly our creations. This will involve both inside (sound box) flying as well as "real world" flying. Compensation will only be the state minimum hourly wages, plus unlimited stealth props for your drone. Perhaps food and an adult beverage can be provided.

Not sure the best way to contact me on this forum... I leave that to your creativity.
Click to expand...

Hi,

When your props are ready, I'd be most interested. I think they will come in handy for filming wildlife.

I just returned from a trip to the Limpopo river in South Africa and was able to film sunbathing crocs from 2 metres before they plunged into the river. The hippos were more difficult and the closest I got was 7 metres before they submerged. Other game would disappear if I came closer than 20 metres (from above).

Yes, stealth props would be great.

Philip
 
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