Hey Paul, for sure I realize I can’t compare it to gas, but I have friend who flies gas and as you said it’s a lower pitch, not as annoying. That’s mainly what I’m getting at. I think the designers of openppg should really be focusing on this issue. This paramotor should have the most efficient props possible as well as swooped tips for sound dampening. They could offer two options, the wood ones or for few hundred extra the more efficient quieter longer lasting props. Even the article in cross country said how annoying the prop noise is. To me it’s the weakest link with openppg and should be top priority to have a prop designed specifically for our use. It sounds like I’m not alone in this thinking 
.
If we could find out where that factory is, maybe they can do the job,
Ya it’s sort of the nature of smaller props. Even though the sound decibel reading is about the same higher pitch is more annoying. I’m sure we could find/design some props that drop the sound down a bit. I’m always looking for options if you guys see anything you think would do the job. Designing one would be a bit of a pain.
Thanks Paul for response.
I’m going to try these electric multi rotor props in 22x10. 5 weeks for delivery. They have nicer profile with swooped tips.
Hey @dzubot,
I already have the ones from XOAR in 22x10!
No difference in noise!
I broke my props, and the XOAR ones were the only ones available for immediate delivery within Germany (3 days) so I decided to buy those instead of waiting for cheaper ones from China.
The shape isn’t much different than the original props, and so does the sound not make a difference.
Just to let you know.
Thanks Etienne good to know just cancelled my order on them since no difference.
I guess only thing left to try is carbon fibre Xoar but there seems to be no way to attach them without having them spin free
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I really want to try something like this. But they would require a custom mount and they aren’t rated to handle the thrust we output. I love the idea of a winglet for both efficiency and sound.
The advantage with T-Motor is, that they not only make the motors, but also Props.
one option is to possibly buy both from them, and have something custom made for our needs.
But that would be up to @Pdwhite and @zjwhitehead to negotiate something with them.
I believe the amount of OpenPPGs that go through their hands with each batch, any manufacturer would be willing to make something custom.
Especially when props do get damaged, and people will buy more throughout the life time of the OpenPPG.
May as well be true for props only.
Unless we are like really 20 to 40 people or so, willing to buy a set of four props, we will not succeed in something custom made.
any chance, @Pdwhite and @zjwhitehead that you would be willing to approach either a only prop manufacturer, or even T-Motor, who make both?
It would be beneficial for future batches, and probably some of us owning earlier batches would love to upgrade to something more efficient and quite.
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Now those are interesting props!
@etienne how did you power the fans on your battery? I’d like to install one on my bms as the temp is close to 60 when I fly. Most computer fans are only 12v max that I can find.
Hi @dzubot,
I googled for 48V fans (didn’t know whether they would exist), but found them at RS.com
I also found a small electronics board that can convert 48 to 12V, but decided to go directly with the 48V fans.
I have the feeling I don’t need them though, usually they’re not running.
I’d like to add that both surfaces of the BMS are aluminum sheets. onto one of them the MOSFETS are directly connected for heat dissipation (the MOSFETS are the pieces that connect and disconnect the current, so they are the pieces that get the hottest).
When building my case, I stuck the aluminum plate with the MOSFETS together with heat-transmissible pads (those that are used to stick coolers to CPUs) directly to the aluminum case.
So the heat is dissipated fairly well onto the whole case.
Interesting. Thanks for fan link and info. That wouldn’t work in my battery as it’s lexan case. What temp do you see your bms get to?
My battery stays at healthy 30° but bms gets very close to 60°, I have to ease off on throttle for it to cool down.
Had a good flight today on third attempt. First two tries I climbed up for couple min and the BMS hit 60° and cut off power. One landing was in nice yellow canola field. Lucky no damage and good landing. I had chase cam on so will share that video. After setting bms high temp cuttoff to 80° I had excellent 30 min flight. Temp is only an issue on take off. During cruise temp was 45°c. Only light lift so mainly on power the entire flight. Start voltage 56v end 44v. One parallel group of batteries dropped to 2.5v cutt off with power on and the bms shut power off so that’s why I didn’t fly longer. All other groups were around 3.15v and the one was 2.8v. Glad I have the bms to save the cells.
My friend and I were both flying (he had scout) at a friends privately registered airstrip. Airstrip owner called and said his neighbor to the east made noise complaint against us to the rcmp. This was mid day flight, and we did not fly over this persons property nor were we flying low. Canada is terrible for this lots of people are against anything that flies. Our towing operations got shut down after neighbors complained and cops threatened to ticket us for distracted driving if we tow in that county again. But yeah I just can’t stress enough how the sound is an issue on this machine. The quieter we can make it the better for everyone including people on the ground.
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@dzubot your Vruzend Battery thread has now officially become the “noise” thread.
I have completed another flight yesterday evening. A nice 25 minutes up in the air (I know, not very long)
but the funny thing happend after landing.
two weeks ago I have flown with my combustion engine, same spot as most of the time, very near to my house. When I landed, I had to be careful, as in the center of the greenfield somebody was playing with his dog (the dog barked like hell, because he was scared by that oversized eagle coming down near him).
So back to yesterday, I landed after that 25min flight on the same greenfield, packed up my glider, and the same guy with the same dog walked by noticing “wow, what I giant drone”
So we started talking, and I told him that we’ve seen each other two weeks ago, that that was a combustion engine whereas this serves the same purpose but is electric, bla bla bla…
And here comes the funny thing: He said: yeah, I noticed that. It’s much quieter.
not that the theory needed any confirmation (the theory that low frequency noise travels much farther than high frequency noise), but his personal perception is as the theory expects.
Note: my wife at staying at our house, watching me fly a few thousand feet away confirmed the same.
Ya, the X4 is definitely more annoying for the pilot but better for the people on the ground if they’re not super close.
That’s really interesting, makes sense the higher pitch doesn’t travel as far. So maybe the noise complaint was actually because of my friend flying his Scout paramotor at the same time as me! He obviously had longer flight, could have been the combination of both us flying as well, definitely louder then just one. Would be interesting to have a DB meter recording sound of the opening and gas at take off to compare noise at various distances.
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Not really to do with paramotor but moreso our mission with electric. Mapped the Columbian icefields today in my Pipistrel virus. Using minimal fuel, 100litres, flying 15,000’ for 7 hours. We are tracking the depletion of the glacier I can’t get any more fuel efficient aircraft other then electric. Once they arrive I’ll be sure to switch. Thanks to the developers of openppg for bringing us an awesome electric flying machine! @Pdwhite
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