Hi, i would be interested to start a new topic : low noise props.
Reducing noise is my main interest in this top project. The main problem with this kind of motor is that props are turning fast and are generating quite a bit of noise. There are certainly new props (22’’ or 23’’ fitting OpenPPG) on the market with the increasing drone market, that offers new designs to reduce noise. Sound could also be studied to work in less bothering frequencys (lower frequencys are usuelly better).
I think the big issue is that our motors are pushing through dirty air. In RC, there is a huge noise difference between pullers and pushers. I try to build puller planes because they are so much quieter.
After that, you want a bigger, slower prop, and you can tell that some of the other e-ppg solutions are very quite with a single big prop. But they have some torque, and give up the potability and low-cost of openppg.
Remember that openppg uses pro-sumer parts, so if an ESC goes out (VERY common; they are hobby grade), it is only $100, not thousands if the ESC of a large prop goes out. The motors are likely to be bullet-proof except for the bearings.
Having said all that, I’d love to see some prop comparisons if we can find CW and CCW versions. Technically you could use all CW or CCW but you might get some weird torque. Might be worth trying to see if there is a substantial drop in dB; the tradeoff might be worth it.
Not much to say about it. It worked, the frame was way heavier than Paul’s (17lbs). The motor from Germany - prop from Europe too. A lot of torque and that why I love Paul’s machine. No regrets.
Hey @Voltair do you still have plans or drawings for that frame still? It look like a good base to resurrect my two prop project onto. I haven’t access to carbon cutting but aluminium is easy to come by. PM me to prevent clogging of the thread if you like.
What a waste - sad!
So many hours and good material gone! And it was so pretty!
I think I am using too many!'s
Someone like Voltair could have used it. I would have paid shipping cost for it and signed a no liability waiver.
It is what it is I guess.
Cheers, Patrick
Liability - when I recycle my old y school wings I cut all the lines. I used to scuba professionally and was drilling holes in my tanks when they were no longer passing inspection.
I have noticed an interesting phenomenon with the noise while listening to my dad fly the OpenPPG:
It sounds as if there are vibrations being transmitted up through the lines to the wing, turning the wing into a giant speaker. I would assume this to be the case because of the odd pulses of reverberation that doesn’t sound like propeller noise.
I know there is almost no vibration from the electric unit, but maybe even that tiniest bit is enough to have such an effect?
It’s not like it’s making the unit any louder, but rather it just changes the tone a little bit. I just thought it was an interesting observation.
Hey there!
I know this thread is old but it’s the right topic for a thought of mine.
I always wondered why owls are that quite while flying. And couldn’t we just use the owl technique to make less noise at flying, too?
So I searched for stuff like that and et voila: It’s not very new.
There are concepts for really quiet ventilators or even wind turbines with this kind of jagged wings.
(They are talking about quieter machines with no power reduction)
Have here been any thoughts to use quiet props?
I’m new here and I don’t even have a paragliding license, but I want to get one. But first I want to check if there’s a clean quiet paramotor on the market.
What ist the prop made of?
I guess plastic with fiberglass?
If injection molding is used, the form of a comb in the prop should be no problem.
For much the same reasons typical airfoils on jumbo jets are very different from those on a WW1 biplane or swallow and sailplane wings are very different from those on an eagle. It’s called Reynolds number. Propellers move through the air at close to the speed of sound (at the tips). Things moving through the air behave very very differently at different speeds. Ventilators and wind turbines move through the air relatively slowly and produce very
There seems to be precious little research into propeller design in the size and thrust range of a PPG. Perhaps as the activity grows in popularity it’ll attract the type of money required for this. I’d love to have a high efficiency ultra quiet propeller design for the X4.
Bratwurst posted this a while back. The website address no longer works so I wonder if this company is still around.
[quote=“bratwurst, post:2, topic:2896, full:true”]
hi, at very high speeds and fast flow, the turbulators on the leading edge work very well. But it was not further developed for ultralight aircraft and ppg because the speeds do not fit well here, for example when cruising. here it is deteriorating. (in my opinion after many tests) air nozzles on the underside of the propeller and air inlet ducts on the front have much more potential. Spikes at the ends bring about 3% more thrust and a reduction in volume of about 1.2 dba. Zigzag bands glued on in 2/3 bring about an increase of up to 5% in certain speeds. in a few months you will see different systems and performance data on my page “turbuprops.com / .at / .de” greetings
Check out these props. They are the propellers used by Delson Aeronautics. They work off the theory that a reduced tip speed is quieter. So they basically stepped it up to a whole new level.
Delson has been extremely quiet on how they have designed their propellers. It took hours of searching to find these propellers in the far background of a single picture posted by some people at competition they attended.
I don’t think it would work great on the sp140 as these propellers are designed to produce the same thrust at half the rpm. As you know torque x rpm = power. So if the sp140 used this propeller, for a given horsepower, the paramotor would feel twice the torque. (1/2 rpm x 2 torque = 1 unit power.) Additionally the prop would be significantly heavier which would make gyroscopic precession really bad and the propeller would cost a fortune.
