a beautiful thing God did to human beings, no matter the kind of nerd. good and effective teaching/expression is a kind of art, and good nerds let people see a bit through their eyes.
@Adolph. As soon as I read your comment, I was reminded of the thermostatically operated clutch fans That I've dealt with over the years. I feel dumb for missing that! Excellent observation. 🤔
I've been searching the internet for 3 straight hours to find anything that explains a curved tip propeller. Im working on a project trying to find out how much a curved/warped blade tip would effect the aircrafts performance. Im trying to figure out if this is hurting my drones performance and if so how much and in what way. Thrust? Top Speed, agility? It won't get any worse than this is now. If I dont use the velcro to keep in place the props flop around and snag on thing. Please advise sir I like the way you explain thing. Thanks in advance
I'm very interspersed in aerodynamics and electronics. By watching your videos, this makes a very good feeling and understanding into me. I want to thank you a lot. And you also talk about efficiency. I'm quite interested in this. Your videos are very effective. And I'm on the way to launch my first project, a rc flying wing. I'm from Bangladesh. Thank you.
Bruce, your enthusiasm to to give information/teach is is wonderfully explained as always in your videos especially to a numb skull like me! you have always given essential and valuable information to the hobbyist and I can vouch for that. I don't usually comment on video's but I felt it was time as I sense that in the last two videos you've posted that your tone is not your usual ' chipper' one ( I sincerely hope I'm wrong). I hope you are able to continue doing what you have been doing which is obviously a passion to you. Thanks again. Joe (UK)
+Alex Curtis I would subscribe to a paid channel by bruce. Even though he operates on a shoestring budget he still produces some of the most informative videos on youtube.
+Joe Musto ...and I thougt Germany was full of restricting regulations and legislation rules. Now I see it´s not. There are strange countries in this world, and they are no "official" dictatorships.
i had no interest in propellers let alone rc planes. but then this video came along and i found myself interested to the point i now have two planes and am shopping for number three. flying these planes have a feeling of flight and freedom all their own. great way to escape for a bit and it started here. his videos are some of the best out there.
Bruce my friend. You've gone and done it again! That was one of the most interesting videos that I have seen for a long while. Your expertise in aerodynamics, RC Quads, RC Fixed Wing, Radio, all collide in this masterpiece. I'll watch it again in a couple of days... :O)
Hi bruce i would like to thank you for what you have done over the years. Your skill and knowledge is like no other. It is still one of my life goals to come and meet you and maybe have a fly. Your channel has been a great part of my life along with many others in this world. I constantly recommend this channel to customers in a hobby shop i work at and will continue to do that. I hope one day this channel can come back as there is no other rc review chanels like it and will never be any like it. Looking forward to a fly thanks Bruce
After finding your ducted propeller videos I was wondering about changing a propeller shape, and then saw this! Thanks for your enthusiasm and education! As a pilot I am curious about more advanced design.
First & Foremost Thank You for your dedication, plethura of knowledge, experience and love for "The Hobby". Indeed it is a sad day when entities like MFN'Z can disrupt the joy of the hobby, and crush your ability to provide for your family. In a short time your videos have guided me through building my first multirotor, programming my transmitter, and setting up my Fpv. the RcModelReviews channel has become a second home and I love sharing the channel for individuals who ask about RC or even just want to learn things like soldering. Definitely looking forward to the new reviews and part 2's.... but at the cost of having no more RCModelReciews post Sept. I am heart broken for your situation and the loss of the Yoda of RC. Thanks for all your hard work, effort and passion You've blessed countless souls and hopefully New Zealand can get their act together.
Very clearly explained. I always thought the winglets were supposed to point to the low pressure side to block the airflow around the tip, not to the high pressure side to lead it along, as it were, so thanks for putting me straight!
This is the same why steel nails tip maked without a hook or harpoon ,like an arrow ,to create more stronger bonds between the wood pieces... Thanks for sharing your idea!
I just wanted to say thank you for the B. S. you have put up with in order to keep this channels content coming, and by the way, I am not a fan of flying, simply an RC enthusiast that can respect good information so I believe your fan base may be more diverse than your aware of, keep up the good fight!
thanks for answering my query. this explains why my tricopter is so much more quiet than the other models as it has the tips on the props. well, that and the slower props speeds.
Props work most efficiently when the tip speed is slightly sub-sonic, so if you have several props on several aircraft, the one with the slower prop (I'm assuming slower in RPM) is also the largest so the tip speed is really the same on all three. Unless one system is not optimised properly and the tip speeds are greatly sub-sonic, but then you got bigger problems than noise...😁
Bruce! Make RC Model Reviews a paid channel (I know you made a video about this). We all love you and are willing to pay for the contents you provide...
Thanks for another very interesting and educational video. [Everytime I see an autogyro I can't help but think of "Those Magnificent Men in their Flying Machines". To me those "contraptions" look absolutely positively like a "suicide note for an extrovert" ;) ] Best regards.
Bruce, you have been one of the greatest online influences in the rc hobby. I just want to say thank you and I really hope this is all figured out. It sounds like that model fly new zeland is a pretty sketchy company. Is there any sort of legal action you could take? Possibly crowd fund this endeavor? We will indeed stick with you Bruce. Good luck and thanks!
Sorry you had to pull the plug Bruce! I'm confident I will hear from you in the near future with more entertaining rc video's! Hope you/or someone else, have the time to make a compilation of the best moments of this channel! Thx man!
Sir.. Am your fan!! u r awesome.. your videos helped me lot in choosing propellers and increasing my drones efficiency, and much more.. thanks a lottt!!!!!!! Adarsh(India)
Currently designing an all electric powered, twin ducted fan powered 2-place aircraft. It is a high wing LSA that will provide a true 90+ minutes of flight time. Both ducted fans will hang from the wings of the aircraft and the. Speeds will be comparable to those found in most traditional 2-place trainers (around 100-knots), and will provide ample room for both the CFI and Student Pilot. Every line will be lifting in its design and very clean....minimal drag! Look very forward to introducing the concept drawings.
Very well explained... it makes us addicted to these amazing propellers facts while convincing me to subscribe here for more! A valuable help to get better inspirations along my workframe around, Thank you!
I just found your channel today and watched a couple vids. I am really impressed with them and subscribed right away. Thank you for doing this its awesome i really appreciate all your work and vids its such valuable information
Really sad that your channel is over. I have looked foward to your video's and will miss you reviewing RTF 250 quads. Its an a shame you have lost your licence to fly but frankly flying on a runway near planes is not a smart move. I wish you all the best in your future adventures sir. gods speed
liked your video alot. I have seen q-tip props a fair bit while working at my local airport. However, all of the props I saw sloped the tip back towards the fuselage - same direction as the thrust. Whereas you have portrayed them in the opposite direction. Keep up the good work!
Bear in mind that the prop effectively compresses air behind it so a back-tilting fence is going to act to "catch" some of that air. A forward facing one may not be as effective. I suspect the best result would be achieved with something like bidirectional sharklets, but unlike ordinary wings props have a lot of other forces acting on them which need to be taken into account. The kinetic energy in a small GA prop at idle has been described as on par with "a 600mph housebrick - on the end of a piece of string" and that's going to put a lot of streching stress on the length of the blade - As a GA pilot, we were always taught to be extremely careful about nicks on the leading and trailing edges of the props as these could turn into propagating cracks in very short order and the last thing you want when in the air is to have your prop suddenly unbalance itself.
Hi Bruce just seen your announcement video and can't tell you how pissed off I am for you. I'm only new to your channel and am just in the middle of building my first racing quad following your build videos which are great, as are all the bids I've watched of yours; very informative, interesting and funny. good luck in the future, hope the tide will turn and you'll be back up here on rcmodelreviews again. Regards and best wishes S Edwards
I love it! Great explanation, Bruce! I wasn't aware prop winglet like devices were mostly for noise reduction. Good to know :-) I suppose helicopters with these drooping tips on their main rotors are there to mostly reduce noise too. Perhaps even for added stealth.
+xjet Hey Bruce, I found a RC map, if you search for New Zealand you can find a couple places. Just thought you'd be interested in it. www.rcgroups.com/forums/maps.php
Well Bruce for some reason in your bad news vid I cant make or read any comments. Sad news to see such a legends channel go the way it is. Wish there was something we could do. Looks like we wont get to see your 250 quad build or your vortex racing quad. The two I've been waiting for, for so long. I will subscribe to your Xjet channel and see what I think. Good luck Bruce, chin up mate
At the speeds our planes fly, the direction of airflow as far as the propeller is concerned is chord-wise. The cause of the tip vortex is mostly the pressure differential between the "top" and "bottom" of the airfoil. While the drooped tips will not produce "upwards lift" relative to the prop's airfoil (forward thrust to the airplane), they can be designed like airline winglets to produce "forward lift", actually pulling on the prop chord-wise and allowing higher rpm for a given power input.
Is there a way to fit r/c multirotors with props like this? Is there a manufacturer who makes them that small? What would fitting a q-tip prop inside an inductor do?
Was sitting here waiting to see a prop made from Q-Tips... 😜 As for avoiding tip vortex, I've seen some props before use an entire ring molded as the circumference of the prop, avoiding tips altogether, and making like a short duct. This could be placed in close proximity to an actual duct to facilitate the effect of a longer or more complete ducting apparatus.
This is cool, it is the same concept of winglets that Boeing started using. I am sure that others use them but Boeing is the only one I can think of atm. The Airbus I worked on has simlar stuff, but they are angled and not really curved.
I enjoyed your video. You speak well, know your stuff and have a vein of humor. I would love to see your talk on thrust. How would you convince people thrust is not pushing against the atmosphere, but the strongest directional force?
I had thought and posted about curved tip propellers in your first ducted video i didnt know they actually existed. Its really cool to see the theroy of them and why they exist more for noise reasons rather than lift/ thurst. So my next thought is why not make the high pressure side of the propellers have a dimple effect like a golf ball for more aero dynamic properities lets see if you can find a propeller company manafacturing that :P
the loudest part of the noise coming off of props, if you pay attention, typically seems to travel in a surprisingly narrow disc of sound, in the same plane the prop spins in. ... which is especially fascinating, (and brings up the subject of focused sound transducers with narrow dispersion I suppose). You'll notice that when airplanes fly by, even at some significant distance, the noise is much greater when the prop tip is pointed at your ear (allowing for speed of sound delay at distance)
G'day Bruce, Yay Team...! In terms of pure efficiency it's always better Engineering is to simply build a Longer Wing, or Rotor Blade, than to pigfrig about trying to sculpt the nuances of the Aerofoil Tips, to try to attempt to shape the Vortices. In practice, if there's a Gyrogoflopter on the Aerodrome then the only thing louder than that within the Boundary Fence is the Flourescent Colours on the Jacket worn by the Gyrogoflopterists... Which is slightly hilarious, but only if one flies Fixed-Wing Aerodynes.... ;-p Ciao !
Sir love the videos. I have a question. What if you put a ball in front of the duct? This would the coriolis effect to suck the air in evenly dispite the angle of the duct. The ball would have to protrude into the duct ending right at the start inpeller blades. The now annular stlye entrace should also speed up the velosity of the in comming air. The ball would seem like an obstruction but only to the force of the air keeping the other side down. The air should theoretically follow the curve of the ball dispite the angle of the duct. Sure youd have to cauculate air flows based on the application but from what i can visualize, the ball should stick out just enough to block the interference from the transition between horizontal and verticle flight. Once in horizontal flight the ball should be spring loaded to push in and funnel more air in from its shock wave, acting like a tunnel ram. This should work. I have some other ideas let me know if youd like to build one?
thank you for a clear explanation! would adding strakes and fences midway down the blade reduce air being contributed to the tip vortices at a lower drag penalty?
Methinks that those tip-vortexes suck some energy (from the engine/motor), so reducing them means more engine-power available for thrust, in stead of creating air-turbulence (and noise). Therefore higher efficiency
What about a plug in the center? It seems to me that by directing air from the less efficient center, to the more efficient tip, with the tip sporting a winglet, should be most efficient. A 1.2 m diameter prop that's rotating at 2500 rpm has a tip speed of 157.2 m/sec. As you go toward the center the speed slows down. That's why the pitch of the blade gets steeper. However, it adds far less to the thrust. R Area Fraction Velocity Newtons Pct Thrust 0.6 0.346 0.306 157.205 10,571.888 0.501 0.5 0.283 0.250 131.004 6,006.755 0.284 0.4 0.220 0.194 104.804 2,990.029 0.142 0.3 0.157 0.139 78.603 1,201.351 0.057 0.2 0.094 0.083 52.402 320.360 0.015 0.1 0.031 0.028 26.201 26.697 0.001 1.131 1.000 ........ 21,117.080 Over half the thrust is produced from less than a third of the propeller disc. It seems to me if you build a propeller with a wing fence, instead of a winglet, you could dispense with a separate duct, and then if you put a nose cone across 5/6th of the wing, you could increase the thrust, by moving the air that flows slowly through the center, near the edge, where it is accelerated to far higher speed. Wing fence example filecache.drivetheweb.com/mr5mr_boeing/86126/K65656-02_med.jpg The trailing edges of the wing fence would be circular like a duct section. If I take the area of each ring in terms of the rim area, and multiply the fraction by the thrust of the rim, I get 34,598.907 Newtons or 1.638x the full thrust. The nose cone and tail cone, are like walls on the inside, and rotate with the propeller just like the tips do. You could increase the number of fins to increase efficiency as well - maybe six fins? The nose cone would look a lot like a centrifugal compressor, since that is what it does, compress the air around the propeller tip against the wing fence on each blade. upload.wikimedia.org/wikipedia/commons/c/c1/Compressor_wheel_Napier_NA357.JPG
Fixed shroud to prop eliminates gap, noise, etc. Would it be optimal solution? Basically, a jet. If you also use contra-rotating props you get huge pressure/thrust. Yes?
SORRY TO HEAR, I am posting this here since the comments have been de-activated on the leaving video post, I will SURELY miss all the informative information that you have posted and helped me in my building and BUYING. This is going to hurt my learning the hobby, I will have to do a lot of searching to find others that offer the informative videos, and hope they do the in depth reviews needed. It is surely BAD that an organization that is SUPPOSE to help, has so much HATE for someone that they FAIL to do their part. Just a bit of info, you are not alone in this type of crap, here in my area it has happened to Amateur Radio, the guys running the clubs fought so much they split the club, and then it was were neither club could get enough support to do any projects. WHAT A SHAME. Boy the self centered attitude of these people is the ruining of many a good serving clubs and organizations. Thanks for being there when I needed the help. Hope it will work out for you..
Good vid. Cheers. Im virtually clueless on the subject bar a few little fun facts but my intuition is leading me to wonder if - wouldn't a significant proportion of the total sound output be due to the leading edge of the propeller 'striking' or travelling through differential pressure zones created in its path by previous propeller(s)? Or wash, or turbulent vortex, or what ever the terminology is for what I'm trying to say lol.
You could, but you'd have to design and fabricate them yourself, since i'm not aware of anyone who makes them in the electric quad size range (3" to 12")
Vegas 666 You are thinking exactly what I was thinking. Quadcopter/drones are so noisy and loud, esp for capturing video. The blade design could be a lot better.
hello sir,by any chance would you explain about boat propellers, will it works if i use this idea on boat prop, can i use this ducted , qtip or combine this qtip and ducted idea? i know air and water is different mediums.but i would like some input from you if you willing to. anyway thanks for this video, now i know the things i dont before,tq
I believe it would have no positive effect and just increase friction/drag. Possibly much more importantly it would limit to the speed it could rotate as those tips will want to splay out the faster it rotates and that would risk rubbing against the ducting. You could move the tips in to give some room but that makes the ducting less effective.
+ROBOFORCERX2000 I would love to have some 5x4 props like this for my mini quad. Its my first one and the thing sounds like an angry wasp! Neighbors haven't complained yet tho. :)
+Owen Buckingham (Dwarf9668) You can probably bend them yourself with a heat-gun and some pliers. But most of the noise comes from vibrations and the motors themselves so I don't know if there will be any noticeable improvement.
What about banded propellors? Where the band rotates with the blades as opposed to a kort nozzle/ ducted prop. Wanting to try one on my outboard engine to increase fuel efficiency and thrust.
I've never been so interested in something I don't care about.
Love this guy's passion.
a beautiful thing God did to human beings, no matter the kind of nerd. good and effective teaching/expression is a kind of art, and good nerds let people see a bit through their eyes.
Beyond True!!☺👍✈
I"ve seen these blade tips on a car's radiator fan, now I know its to reduce noise output.
56years old and still learning, thanks Bruce.
Thx dude. I just learned from you too. Good day
@Adolph. As soon as I read your comment, I was reminded of the thermostatically operated clutch fans That I've dealt with over the years. I feel dumb for missing that! Excellent observation. 🤔
I've been searching the internet for 3 straight hours to find anything that explains a curved tip propeller. Im working on a project trying to find out how much a curved/warped blade tip would effect the aircrafts performance. Im trying to figure out if this is hurting my drones performance and if so how much and in what way. Thrust? Top Speed, agility? It won't get any worse than this is now. If I dont use the velcro to keep in place the props flop around and snag on thing. Please advise sir I like the way you explain thing. Thanks in advance
I'm very interspersed in aerodynamics and electronics. By watching your videos, this makes a very good feeling and understanding into me. I want to thank you a lot. And you also talk about efficiency. I'm quite interested in this. Your videos are very effective. And I'm on the way to launch my first project, a rc flying wing. I'm from Bangladesh. Thank you.
Bruce, your enthusiasm to to give information/teach is is wonderfully explained as always in your videos especially to a numb skull like me! you have always given essential and valuable information to the hobbyist and I can vouch for that. I don't usually comment on video's but I felt it was time as I sense that in the last two videos you've posted that your tone is not your usual ' chipper' one ( I sincerely hope I'm wrong). I hope you are able to continue doing what you have been doing which is obviously a passion to you. Thanks again.
Joe (UK)
+Joe Musto Thanks Joe. Yeah, you're right... the mood is not so high here right now and I'm feeling a bit under the weather.
+Alex Curtis I would subscribe to a paid channel by bruce. Even though he operates on a shoestring budget he still produces some of the most informative videos on youtube.
+Joe Musto Ditto.
If it had not been for Bruce I would never have made my ZMR improved quality arms, he started me building out of carbon.
Good luck Bruce.
+Joe Musto
...and I thougt Germany was full of restricting regulations and legislation rules. Now I see it´s not. There are strange countries in this world, and they are no "official" dictatorships.
i had no interest in propellers let alone rc planes. but then this video came along and i found myself interested to the point i now have two planes and am shopping for number three. flying these planes have a feeling of flight and freedom all their own. great way to escape for a bit and it started here. his videos are some of the best out there.
Bruce my friend. You've gone and done it again!
That was one of the most interesting videos that I have seen for a long while.
Your expertise in aerodynamics, RC Quads, RC Fixed Wing, Radio, all collide in this masterpiece. I'll watch it again in a couple of days... :O)
Hi bruce i would like to thank you for what you have done over the years. Your skill and knowledge is like no other. It is still one of my life goals to come and meet you and maybe have a fly. Your channel has been a great part of my life along with many others in this world. I constantly recommend this channel to customers in a hobby shop i work at and will continue to do that. I hope one day this channel can come back as there is no other rc review chanels like it and will never be any like it.
Looking forward to a fly thanks Bruce
Bruce - Very interesting and informative. It's right what they say, "you learn something new every day" - especially after viewing your videos !
After finding your ducted propeller videos I was wondering about changing a propeller shape, and then saw this! Thanks for your enthusiasm and education! As a pilot I am curious about more advanced design.
First & Foremost Thank You for your dedication, plethura of knowledge, experience and love for "The Hobby". Indeed it is a sad day when entities like MFN'Z can disrupt the joy of the hobby, and crush your ability to provide for your family. In a short time your videos have guided me through building my first multirotor, programming my transmitter, and setting up my Fpv. the RcModelReviews channel has become a second home and I love sharing the channel for individuals who ask about RC or even just want to learn things like soldering. Definitely looking forward to the new reviews and part 2's.... but at the cost of having no more RCModelReciews post Sept. I am heart broken for your situation and the loss of the Yoda of RC. Thanks for all your hard work, effort and passion You've blessed countless souls and hopefully New Zealand can get their act together.
Very clearly explained. I always thought the winglets were supposed to point to the low pressure side to block the airflow around the tip, not to the high pressure side to lead it along, as it were, so thanks for putting me straight!
Thanks Bruce. This is why I never miss your videos.
This is the same why steel nails tip maked without a hook or harpoon ,like an arrow ,to create more stronger bonds between the wood pieces... Thanks for sharing your idea!
What a great education video and the example of the autogyro helicopter at the end. It really is just the engine you mostly hear. That's impressive.
I just watched your latest video, I am really sorry for what has happened. You have helped me a lot with your videos. Thank you for all you have done.
I just wanted to say thank you for the B. S. you have put up with in order to keep this channels content coming, and by the way, I am not a fan of flying, simply an RC enthusiast that can respect good information so I believe your fan base may be more diverse than your aware of, keep up the good fight!
Bruce, you have done it again... A very informative video lesson on aerodynamics with a practical example to boot. Great stuff. Thank you!!!
You consistently explain things very well, thanks.
Informative yet easily understood, as usual. Thanks Bruce!
You're such a good teacher! Keep making these videos, you're one of a kind...
Going to miss a wonderful instructor. I am pissed for you as well! Wishing you and the Mrs. a wonderful change in your future!
thanks for answering my query. this explains why my tricopter is so much more quiet than the other models as it has the tips on the props. well, that and the slower props speeds.
Props work most efficiently when the tip speed is slightly sub-sonic, so if you have several props on several aircraft, the one with the slower prop (I'm assuming slower in RPM) is also the largest so the tip speed is really the same on all three. Unless one system is not optimised properly and the tip speeds are greatly sub-sonic, but then you got bigger problems than noise...😁
hi bruce i would like to thank you for what you have done over the years
Once again you made this very easy to understand. Wish I had your ability when i was at university. Thank you.
Bruce! Make RC Model Reviews a paid channel (I know you made a video about this). We all love you and are willing to pay for the contents you provide...
Thanks for another very interesting and educational video.
[Everytime I see an autogyro I can't help but think of "Those Magnificent Men in their Flying Machines". To me those "contraptions" look absolutely positively like a "suicide note for an extrovert" ;) ]
Best regards.
Bruce, you have been one of the greatest online influences in the rc hobby. I just want to say thank you and I really hope this is all figured out. It sounds like that model fly new zeland is a pretty sketchy company. Is there any sort of legal action you could take? Possibly crowd fund this endeavor? We will indeed stick with you Bruce. Good luck and thanks!
Good explanation. A bit like a science class only now it's interesting while in school it wasnt :-)
Testify
That's why a good teacher can make a big difference
@@94JAVS Yeah, I never hated school for that, everything almost was interesting to me!
Sorry you had to pull the plug Bruce! I'm confident I will hear from you in the near future with more entertaining rc video's!
Hope you/or someone else, have the time to make a compilation of the best moments of this channel!
Thx man!
Sir.. Am your fan!! u r awesome.. your videos helped me lot in choosing propellers and increasing my drones efficiency, and much more.. thanks a lottt!!!!!!!
Adarsh(India)
Currently designing an all electric powered, twin ducted fan powered 2-place aircraft. It is a high wing LSA that will provide a true 90+ minutes of flight time. Both ducted fans will hang from the wings of the aircraft and the. Speeds will be comparable to those found in most traditional 2-place trainers (around 100-knots), and will provide ample room for both the CFI and Student Pilot. Every line will be lifting in its design and very clean....minimal drag! Look very forward to introducing the concept drawings.
You did a great job as usual. Thanks for all the very informative videos.
Thumbs up for great instructions on ducted fans - oh and the Swanndri jacket, got a coat myself, - Fond memory from my days as a sheep herder
Thank you for teaching us this information. I'd love to be a half Japanese high school girl with you as a English language teacher.
Very well explained... it makes us addicted to these amazing propellers facts while convincing me to subscribe here for more! A valuable help to get better inspirations along my workframe around, Thank you!
I just found your channel today and watched a couple vids. I am really impressed with them and subscribed right away. Thank you for doing this its awesome i really appreciate all your work and vids its such valuable information
hey bud, just caught the 'bad' news video. I have found the videos great. I hope things turn around for you. thanks for the effort and time
Really sad that your channel is over. I have looked foward to your video's and will miss you reviewing RTF 250 quads. Its an a shame you have lost your licence to fly but frankly flying on a runway near planes is not a smart move. I wish you all the best in your future adventures sir. gods speed
liked your video alot. I have seen q-tip props a fair bit while working at my local airport. However, all of the props I saw sloped the tip back towards the fuselage - same direction as the thrust. Whereas you have portrayed them in the opposite direction. Keep up the good work!
Bear in mind that the prop effectively compresses air behind it so a back-tilting fence is going to act to "catch" some of that air. A forward facing one may not be as effective.
I suspect the best result would be achieved with something like bidirectional sharklets, but unlike ordinary wings props have a lot of other forces acting on them which need to be taken into account.
The kinetic energy in a small GA prop at idle has been described as on par with "a 600mph housebrick - on the end of a piece of string" and that's going to put a lot of streching stress on the length of the blade - As a GA pilot, we were always taught to be extremely careful about nicks on the leading and trailing edges of the props as these could turn into propagating cracks in very short order and the last thing you want when in the air is to have your prop suddenly unbalance itself.
Hi Bruce
just seen your announcement video and can't tell you how pissed off I am for you. I'm only new to your channel and am just in the middle of building my first racing quad following your build videos which are great, as are all the bids I've watched of yours; very informative, interesting and funny.
good luck in the future, hope the tide will turn and you'll be back up here on rcmodelreviews again.
Regards and best wishes
S Edwards
I love it! Great explanation, Bruce! I wasn't aware prop winglet like devices were mostly for noise reduction. Good to know :-)
I suppose helicopters with these drooping tips on their main rotors are there to mostly reduce noise too. Perhaps even for added stealth.
Bruce, your videos are great. I use them all the time for teaching. Great Stuff. See you on "Drone and Sundry". -J
Thanks for the sound of the(912 Rotax)gyrocopter.
That prop is a lot quieter than other ultra lights that I have heard.
This is a great second part to the UHF review. You had some good points on the.. Oh. Nevermind.
+PoppaShocka LOL... there's always one eh? :-)
+xjet Hey Bruce, I found a RC map, if you search for New Zealand you can find a couple places. Just thought you'd be interested in it. www.rcgroups.com/forums/maps.php
+Drew Gardner LOL... kind of fitting that there's nothing at Tokoroa.
***** Haha sorry, There are none around me either!
Really good explanation. Thanks Bruce.
Well Bruce for some reason in your bad news vid I cant make or read any comments. Sad news to see such a legends channel go the way it is. Wish there was something we could do. Looks like we wont get to see your 250 quad build or your vortex racing quad. The two I've been waiting for, for so long. I will subscribe to your Xjet channel and see what I think. Good luck Bruce, chin up mate
This is marvellous, I really enjoyed
I can't remember better teacher of anything.
and I'm almost old and born in a teacher's family, grown around "teachers".
Fantastic video, very interesting. Thank you Bruce.
At the speeds our planes fly, the direction of airflow as far as the propeller is concerned is chord-wise. The cause of the tip vortex is mostly the pressure differential between the "top" and "bottom" of the airfoil.
While the drooped tips will not produce "upwards lift" relative to the prop's airfoil (forward thrust to the airplane), they can be designed like airline winglets to produce "forward lift", actually pulling on the prop chord-wise and allowing higher rpm for a given power input.
I did not know about "Q" tip props. Thank you.
Is there a way to fit r/c multirotors with props like this? Is there a manufacturer who makes them that small?
What would fitting a q-tip prop inside an inductor do?
When geese fly in formation they pick up some of the lift created by the vortex from the bird in front so they expend less energy
Was sitting here waiting to see a prop made from Q-Tips... 😜
As for avoiding tip vortex, I've seen some props before use an entire ring molded as the circumference of the prop, avoiding tips altogether, and making like a short duct. This could be placed in close proximity to an actual duct to facilitate the effect of a longer or more complete ducting apparatus.
New drinking game, each time this teacher say high pressure or low pressure, take a shot.
This is cool, it is the same concept of winglets that Boeing started using. I am sure that others use them but Boeing is the only one I can think of atm. The Airbus I worked on has simlar stuff, but they are angled and not really curved.
Great analysis !!! 👍🏻👍🏻
Tyu, great video. Wondering why it isnt used in fans, performance is same but noise is reduced.
Good stuff Bruce thanks for the info.
I enjoyed your video. You speak well, know your stuff and have a vein of humor. I would love to see your talk on thrust. How would you convince people thrust is not pushing against the atmosphere, but the strongest directional force?
Very interesting. Thanks Bruce.
Thank you Bruce, great explanation. I was wondering why my pusher was so much noisier than my...er...puller!
I had thought and posted about curved tip propellers in your first ducted video i didnt know they actually existed. Its really cool to see the theroy of them and why they exist more for noise reasons rather than lift/ thurst. So my next thought is why not make the high pressure side of the propellers have a dimple effect like a golf ball for more aero dynamic properities lets see if you can find a propeller company manafacturing that :P
very well expalined ... Keep up the excellent work
My comment on your ducted video one month ago.. about noisyless props.. cheers... :)
Really like your white board tutorials Bruce. Hope we get to see more in the future? :-)
Superb stuff ! Thanks Bruce
had this idea some years ago and built some 5-blade models. should go into this again since it seems to trend ;)
the loudest part of the noise coming off of props, if you pay attention, typically seems to travel in a surprisingly narrow disc of sound, in the same plane the prop spins in. ... which is especially fascinating, (and brings up the subject of focused sound transducers with narrow dispersion I suppose). You'll notice that when airplanes fly by, even at some significant distance, the noise is much greater when the prop tip is pointed at your ear (allowing for speed of sound delay at distance)
The low pressure vortex will pull the propeller and grant additional thrust
Very enjoyable, thanks Bruce
Thanks B I learned a few interesting things.
G'day Bruce,
Yay Team...!
In terms of pure efficiency it's always better Engineering is to simply build a Longer Wing, or Rotor Blade, than to pigfrig about trying to sculpt the nuances of the Aerofoil Tips, to try to attempt to shape the Vortices.
In practice, if there's a Gyrogoflopter on the Aerodrome then the only thing louder than that within the Boundary Fence is the Flourescent Colours on the Jacket worn by the Gyrogoflopterists...
Which is slightly hilarious, but only if one flies Fixed-Wing Aerodynes....
;-p
Ciao !
Not true, the jets are slightly louder than the outfits.... 🤣
Bruce, my prayers are with you. if I could afford to help I would.
nice one mate
Sir love the videos. I have a question. What if you put a ball in front of the duct? This would the coriolis effect to suck the air in evenly dispite the angle of the duct. The ball would have to protrude into the duct ending right at the start inpeller blades. The now annular stlye entrace should also speed up the velosity of the in comming air. The ball would seem like an obstruction but only to the force of the air keeping the other side down. The air should theoretically follow the curve of the ball dispite the angle of the duct. Sure youd have to cauculate air flows based on the application but from what i can visualize, the ball should stick out just enough to block the interference from the transition between horizontal and verticle flight. Once in horizontal flight the ball should be spring loaded to push in and funnel more air in from its shock wave, acting like a tunnel ram. This should work. I have some other ideas let me know if youd like to build one?
Always interesting and informative. Thanks!
keep up the good work . love your work
What does q stand for
thank you for a clear explanation! would adding strakes and fences midway down the blade reduce air being contributed to the tip vortices at a lower drag penalty?
Methinks that those tip-vortexes suck some energy (from the engine/motor), so reducing them means more engine-power available for thrust, in stead of creating air-turbulence (and noise). Therefore higher efficiency
What about a plug in the center? It seems to me that by directing air from the less efficient center, to the more efficient tip, with the tip sporting a winglet, should be most efficient.
A 1.2 m diameter prop that's rotating at 2500 rpm has a tip speed of 157.2 m/sec. As you go toward the center the speed slows down. That's why the pitch of the blade gets steeper. However, it adds far less to the thrust.
R Area Fraction Velocity Newtons Pct Thrust
0.6 0.346 0.306 157.205 10,571.888 0.501
0.5 0.283 0.250 131.004 6,006.755 0.284
0.4 0.220 0.194 104.804 2,990.029 0.142
0.3 0.157 0.139 78.603 1,201.351 0.057
0.2 0.094 0.083 52.402 320.360 0.015
0.1 0.031 0.028 26.201 26.697 0.001
1.131 1.000 ........ 21,117.080
Over half the thrust is produced from less than a third of the propeller disc. It seems to me if you build a propeller with a wing fence, instead of a winglet, you could dispense with a separate duct, and then if you put a nose cone across 5/6th of the wing, you could increase the thrust, by moving the air that flows slowly through the center, near the edge, where it is accelerated to far higher speed.
Wing fence example
filecache.drivetheweb.com/mr5mr_boeing/86126/K65656-02_med.jpg
The trailing edges of the wing fence would be circular like a duct section.
If I take the area of each ring in terms of the rim area, and multiply the fraction by the thrust of the rim, I get 34,598.907 Newtons or 1.638x the full thrust. The nose cone and tail cone, are like walls on the inside, and rotate with the propeller just like the tips do.
You could increase the number of fins to increase efficiency as well - maybe six fins? The nose cone would look a lot like a centrifugal compressor, since that is what it does, compress the air around the propeller tip against the wing fence on each blade.
upload.wikimedia.org/wikipedia/commons/c/c1/Compressor_wheel_Napier_NA357.JPG
Fixed shroud to prop eliminates gap, noise, etc. Would it be optimal solution? Basically, a jet. If you also use contra-rotating props you get huge pressure/thrust. Yes?
SORRY TO HEAR,
I am posting this here since the comments have been de-activated on the leaving video post, I will SURELY miss all the informative information that you have posted and helped me in my building and BUYING. This is going to hurt my learning the hobby, I will have to do a lot of searching to find others that offer the informative videos, and hope they do the in depth reviews needed. It is surely BAD that an organization that is SUPPOSE to help, has so much HATE for someone that they FAIL to do their part. Just a bit of info, you are not alone in this type of crap, here in my area it has happened to Amateur Radio, the guys running the clubs fought so much they split the club, and then it was were neither club could get enough support to do any projects. WHAT A SHAME. Boy the self centered attitude of these people is the ruining of many a good serving clubs and organizations. Thanks for being there when I needed the help. Hope it will work out for you..
Good vid. Cheers. Im virtually clueless on the subject bar a few little fun facts but my intuition is leading me to wonder if - wouldn't a significant proportion of the total sound output be due to the leading edge of the propeller 'striking' or travelling through differential pressure zones created in its path by previous propeller(s)? Or wash, or turbulent vortex, or what ever the terminology is for what I'm trying to say lol.
wow the blade was moving astonishingly slow of that auto gyro for it to take off
Thanks Bruce.
Q-tip props have been used in a few planes. The story is told of the FAA inspector who grounded such a plane because the props were bent.
could i use 4 q-tip propellers to build a quieter quad copter?
You could, but you'd have to design and fabricate them yourself, since i'm not aware of anyone who makes them in the electric quad size range (3" to 12")
Vegas 666 You are thinking exactly what I was thinking. Quadcopter/drones are so noisy and loud, esp for capturing video. The blade design could be a lot better.
The U.S. Navy uses those propellers on their E2C-Hawkeye
Cant it also "push" some air in - take it from the side and push it backwards - producing thrust?
Thank you for these fundamentals-videos.
Your clarity & enthusiasm both are much appreciated.
Salut, Namaste, & Kaizen, eh?
_ /\ _
hello sir,by any chance would you explain about boat propellers, will it works if i use this idea on boat prop, can i use this ducted , qtip or combine this qtip and ducted idea? i know air and water is different mediums.but i would like some input from you if you willing to. anyway thanks for this video, now i know the things i dont before,tq
You explained it well.
I have fallen in love with autogiros.
where can I find UA-cam showing test comparison of ducted propeller to same size not doctored
Robert Mikulec Sr. Here you go! Totally blew my mind how much more thrust he got with the duct. ua-cam.com/video/hPUVrRqhyMk/v-deo.html
So would adding the wing tips to a ducted propeller make it even quieter and more efficient, or would it have no effect?
I believe it would have no positive effect and just increase friction/drag. Possibly much more importantly it would limit to the speed it could rotate as those tips will want to splay out the faster it rotates and that would risk rubbing against the ducting. You could move the tips in to give some room but that makes the ducting less effective.
Excellent explanation.
I wonder will we ever see such props for miniquads:)
+ROBOFORCERX2000 I would love to have some 5x4 props like this for my mini quad. Its my first one and the thing sounds like an angry wasp! Neighbors haven't complained yet tho. :)
+Owen Buckingham (Dwarf9668) You can probably bend them yourself with a heat-gun and some pliers. But most of the noise comes from vibrations and the motors themselves so I don't know if there will be any noticeable improvement.
+pyro1324 try it without the props on and you will see how quiet it is comparatively.
What about banded propellors? Where the band rotates with the blades as opposed to a kort nozzle/ ducted prop.
Wanting to try one on my outboard engine to increase fuel efficiency and thrust.