How to choose the right props for your quadcopter: FPV Freestyle, Racing, and Long Range
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- čas přidán 16. 04. 2021
- In this video I take a deep dive on some of the principles that govern the performance of the props that we use on our quads. I look at the effect of diameter, disc loading, number of blades and angle of attack on prop efficiency and thrust. Finally we look at what props are most suitable for different applications.
This video was reuploaded to include a better treatment of L/D ratio as it relates to efficiency. Thank you to the commenters who brought this to my attention.
Motor selection video: • How to pick the best m...
Slides: drive.google.com/drive/folder...
Prop tip sped calculator: warpdriveprops.com/propspd2.html
Support me on Patreon: / chris_rosser
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The fact that you incorporate actual science instead of "Oh, I flew this one, then that one, and then I liked this one better." Well done mate.
Thank you, I try to take feel out of the equation a little bit because 1. I'm not a pro pilot 2. It's very subjective and can sometimes lead you down the wrong path for the right reasons or the right path for the wrong reasons!
Bardwell sent me over to check your channel out, really glad that he did. Being an ex aircraft and helicopter mechanic, I guess that from my technical education required to get my license, a lot of the principles that you explain seem to be common knowledge, but that is only because of my own education. You did a great job of explaining a uncommon topic! Ain’t no perfect prop for all conditions, you have to choose the one that fits your flying parameters.
I’d love to see an updated take on this with the new wave of all these 5.1 props like 51433, 51466, 51477, etc.
How much do I like your videos? I watch them twice. They are so full of great technical analysis that I pick up details I missed the first time through. Keep it up!
Wow, thank you! I appreciate your positive support.
Love this, Looking forward to the next load of knowledge you can share with us. Keep it up !!
This is insanely good content. Learned more about props from this video than an entire course in aerodynamics at uni! Your explanations are great, thanks for taking your time to make these videos!
Glad it was helpful!
*Chris Rosser* 💯 🏆 🥇
Щиро дякую за просвітницьку 🧑🔧🔬🧠✨ діяльність, дуже корисно!
Brilliant! I really like the academic approach! Well done!
Thank you very much for this video and your scientific analyses. I have been waiting for discussions like this in FPV. I look forward to all of your future content.
Glad you enjoyed it!
Good video. Appreciate your hard work in making such quality content.
Your channel has given me a while new excitement for drones, I'm now extremely interested in the building and perfecting of the quad to squeeze performance. Before I couldn't digest it all, but giving us an understanding in more understandable terms will allow me to further delve in
This content is awesome kabab fpv had a video on the babyhawk 2 hd and had talked about how it’s frame resonance was really good then bardwell talked about it now I can’t stop thinking about this is awesome stuff you are doing !!
G'WeekenD Mr. Thanks 4 everything U do 4 this great community. I really enjoy your content, takeCare mate
At last, I understand prop wash, your videos are soooo good. Thank you so much. Having the equations and their explanations to understand the physical phenomenons is absolutely marvelous.
You are so welcome!
This video was fantastic. Thank you for doing this.
I learned something today! Great video, thanks for uploading!
Very excited to watch as your channel inevitably grows tremendously. You combine some of my favorite aspects of the likes of Joshua Bardwell and KababFPV. Please keep up the good work because I definitely learned a lot and enjoyed every second of this video. Also, I literally checked to see if you had a review of the Glide frame and what a coincidence that it's your next video
I really appreciate the positive comment and can't wait to hear what you think of the analysis of the FPVCycle Glide Frame.
I've been here from day #1, and I don't regret it. I love how it's nothing but straight information. Keep up the the explanations coming, it's always interesting
Thanks Vitroid! I really appreciate your support
The man Chris does it once more...outstanding vid bruh
Again a really good video!
Thank you for sharing so useful information! Keep on going!
Thank you! Will do!
If my algebra teacher would talk in the same interesting way, I would graduate from high school with A+
Just found why need to decrease kv, going to 6" and higher diameter props. I knew before that I had to do this, but now I know why :) I didn't even think about the speed of the propeller tip before.
Thank a lot! You doing great job!!
Thank you! I have an advantage over your algebra teacher: FPV is more awesome than calculus 😎
@@ChrisRosser i was gonna say the same thing: you have interest in the subject. Changes everything haha
thanks Chris, very informative content
your videos pushed me to the other side of peak on dunning-kruger curve. thank you.
You're welcome, we're all on the climb up the next slope now!
Some great content dude
Thanks! I appreciate your support.
It is!!
So detailed and complete, I love it!
I was freestyling at 2700 kv 4s with 5042 props already though :p.
Awesome information Sir
Thank you this helps tremendously!! Your'e video's are very educational I appreciate the knowledge!
dude you are my new favorite person, thank you!
Happy to help!
Great content.
Excellent work. Very informative video. Keep it up
Thanks, will do! It's really nice of you to leave a positive comment 😁
Damn. You posted this just after I passed my canadian rpas exam. Stall mechanics was one of the questions!
thanks the video clarified what prop should I use thanks a lot
Glad I could help! Thanks for your support.
Best FPV video I have ever seen, beats even JB in my opninion. Do more please!!
Thank you for your wonderful comment. I'm not sure I'm quite at JBs level but I love that you are finding my videos valuable.
even Paweł Spychalski, if nothing else Chris does not say "basic-A-lly" (I pick on Paweł only because I have the same outrageous accent)
both your disk loading and prop tip speed lessons helped me 1) verify that someone's 3.5" digital toothpick actually matches kabab's analog 3" toothpick characteristics, and 2) how to calculate the ideal and maximum motor output % to make my over-kv motors match that same config. you are a legend for bringing sanity and safety to this hobby
Congrats on 10k subs today! I was one of the latest 😎👍 I only comment here because this is the video I was watching when I noticed the change from "9.99k" to "10k."
Your almost purely scientific approach lifts the fog of uncertainty in several aspects of quad build considerations. I fully agree with the rest of these comments saying it was great to find you and learn so much more than expected! Keep it coming!
Thank you! Very excited to keep producing the videos 😁
Great content for some one luke me who wants to understand everything thanks Chris !
Now this is CONTENT!!!!💯👍 My only mistake is that I didn't find out about Chris until recently!!!! When the Yoda of fpv had his quad filter set by Chris and absolutely loved it I was like ok.....I need to find this Chris guy 🤣 I subbed immediately after watching the first vid I saw....just great information all around man✌....PS.....YODA IS JB 😁
So much insight! Thank you. I have always thought that props with more pitch should be more efficient. Many youtubers told otherwise and it really confused me.
It depends a lot on how you fly but if you fly reasonably fast and are gentle with the throttle you can really benefit from a steeper pitch prop! Thank you for your comment 😁
Part of the reason for the confusion is that most pilots don't mean the same thing when they say "efficiency", as Chris does. When testing motors, efficiency means grams of thrust per watt of power. But when pilots talk about efficiency, they usually mean longer flight time. A lower pitch prop will usually give longer flight times all else being equal, because it makes less thrust and so it draws less power.
Lower pitch props also load the motor less. This is especially true when talking about a high kv motor, which will need to draw more current to generate the torque to try to spin the higher-pitch prop at higher rpms. I think the effect of the prop loading down the motor is not taken into account when it's said that lower pitch props are more efficient. Rather, the motor is assumed to have infinite torque reserve, and so the motor's performance doesn't change as the prop changes. But real motors don't have infinite torque reserve.
Take a 6S battery and a 1900kv motor and spin a Ethix S2 prop and a Gemfan 51499 on it. I think you'll find that the 51499 is less efficient in terms of grams per watt due to it heavily loading down the motor, and because at higher rpm you enter the stall condition that Chris discussed. But even if that turns out to be false, I'm 100% sure that you'll get longer flights on the S2, simply because it's making less thrust. And that's what lay-people usually mean when they say a prop is "more efficient".
@@JoshuaBardwell Totally agree. Most pilots mean flight time, when they say "efficient". I also think that manufacturers are partly to blame. Such as every motor is advertised as efficient, light, powerful, and easy to control.
I finally understand why all the top pilots use low pitch props for freestyle and what I've been doing wrong with my own prop choices. Thank you!
Great info. Thank you!
I feel like this is a very expensive lesson for free. Amazing level of detail here in a science I don't know jack about
Thanks so much! I hope you found it useful and enjoy the other videos 🤠
Very informative videos.
Glad you think so, thanks for your comment!
As a fellow aero engineer, great presentation.
very well done video. i like the maths and thinking.... bravo!!!!
Thank you! Cheers!
Its really helping
this was a very useful 18+ minutes of my life, thank you! now choosing a new props would be much less of intuition/reviewers influence and much more of understanding of physical processes which make quadcopter fly. subscribed!
Glad it was helpful! Hope this helps you to find your perfect props.
@@ChrisRosser it will for sure!
Very useful, thanks!
You're welcome!
i have a big box with 30 packs of differents new props (for test only) and when i have a new quad, i take the box to test and know for the quad i have buid what props are the best. thank you for this video ;)
So where my physics teacher ears are burning. Because I am set here like WHY DID I NOT LISTEN IN CLASS!!!!. Good info really putting this with your motor video I have a better feeling about the props I am picking for my rigs. Instead of just well so and so use this let's see.
I'm glad to hear that, hopefully you'll find the perfect props for you more quickly now you know what to look for.
I was scouring the internet for equations to solve for the right props, and I have FINALLY FOUND IT. also I'm so glad I took AP physics
This justifies my findings in my prop reviews.
I love it when theory aligns with experience!
The moral of the story is that 5043 props are all that you ever need as it seems to strike the ideal balance.
The high pitch for lr was a big ah ha momemnt for me. Thanks man.
No worries, don't forget that throttle limit otherwise you might be tempted to use all that performance and kill your flight times.
yes excelent video thank u.
Hi Chris- love the scientific approach- would be really great to see how theory stood up to practice by setting up a double blind trial with some experienced pilots - suspect it would be difficult to get sufficient numbers for a significant result though
Really good information thanks 👍😎
Thanks for the comment. I really appreciate that you watch and comment on every video 😁
@@ChrisRosser hey you’re producing some of the most interesting technical videos in the hobby that I’ve seen in a long time mate 👌
I have so many questions I would love to ask you, like the does putting seperate ESCs on the arms have any appreciable effect on resonance compared to using a 4in1?
Scientific approach which i like.
I like your positive comment. Thank you!
As a scientist and also a pilot... FOUR THUMBS UP for you my man
Thanks for the support! 😁
@@ChrisRosser one of my group friends keep asking me if placement of VTX above Power Cables will affect the components from the VTX. I just simply says yes for micro magnetic field. Might be a good theme to cover, maybe?
I can only imagine a prop hitting 1.0 Mach and hearing a bang as a trail of fire burning on a road is all that is left as the drone travels back to the future.
(I really wish the x and y axis where labeled in the 'prop tip speed efficiency' graph😬) Great content Chris! Thank you for the educational material.
This series of videos is amazing. I have some questions, do these same pitch recommendations apply to all propeller diameters?, for example 3-4 in; and what would be the best propeller for a cinewhoop to get the maximum flight time?
Thanks - helpfull
Awesome
No you're awesome! Thanks buddy 😁
Thanks.
No worries!
thumbs up new sub, thanks for sharing
Thank you for the sub. It makes a huge difference when I speak with manufacturers regarding support for testing.
Once again you have put out some very useful information that will help us all build and design better flying quads. Your points are clear and concise and understandable for even people like me with no engineering background. You more or less answered this in the video but how does weight factor in to prop selection for 5" freestyle quads? I have some that are in the mid 600g and others close to 725g AUW. Would the weight difference lead to choosing different props all else being equal? Higher pitch on heavier quads? Thank you Chris!
As you increase AUW your inflow velocity in a hover is going to increase and so you might pick a steeper prop for more efficiency. If you do a lot of reverse flow moves that could affect propwash handling so another solution is to go up to a 5.1" or 5.5" if you can and keep a lower pitch.
@@ChrisRosser Thanks for taking the time to answer my question and that makes a lot of sense. I would like to see some more prop manufacturers make 5.5" props especially low pitch ones. I haven't seen any freestyle 5.5" props yet but would love to try some out for my heavier quad that can actually accommodate the 5.5 props (marmotte lol).
@@chibikaiju922 Actually have bought some 5.5" props (also for a Marmotte frame) but only had time to do arround 5 packs or so. I really like how stable they make my heavy quad (717g) and also they just made my marmotte the fastest quad I have, but my batteries hate them. My motors are so much more capable of pulling Amps (before max arrond 96A, now all the battery has to offer, arround 130A). That went that far, that I accidently had a sag (if you can call it like that) to 8.8V on my 4s-Lipo. I hadn't pulled to many mAh at that point, but just the gigantic, onholding load killed it. Just did a dive/half loop over a big tree and hat to catch it, and then the volage began to sag out, so I had to throttle even more, but that only resulted in more amps and so on, untill I hitted the ground (at 8.8V XD ).
Okay, now back to the prop:
It is definetly a little quieter at hover and also I can hover now at arround 7A, before it was arround 11A which i guess is pretty amazing, and also the normal flying takes a little less Amps, but as I said, when u punch, the motors just can work hader and pull more Amps. So there is just a benefit for me in that area.
I had some problems with some pretty significant bounce-backs after fast flips and rolls, guess that will be mostly an issue of retuning the PIDs, but havent had time to look into it.
All in all, I really would reccomend everyone that has a quad with 700g+ to just try a set of 5.5" props, I have bought these: HQProp Durable 5535.
Also I bought some 5" props with 4 blades, havent had any time to test these, but I hoped to just get more surface area and maybe also a better flying quad when its rather in the heavy part for normal 5" 3baldes, but as I said that is just my hope and will be tested as soon as the weather here gets better.
Hope I could help you, have fun ;^D
Thanks for the insights. I though do not exacly buy into your concrete prop spec recommendation. I guess that also heavily depends on the prop manufacturer and how they form the tip ends. So as relative recommendations in the line of one manufacturer, I do buy into this.
For freestyle imho the compromise is that you need "punch" and you have to deal with all this adverse flow conditions. Most freestyle videos are so appealing because there is smoothness and flow interrupted by phases of hard punchs. But certainly going for the most high-pitch prop is not the right thing to do.
You are correct, this can only be a guide, to try and help people know what type of prop might be right for them. Thanks for your comment!
Another great presentation. I've been thinking about pitch vs inflow speed with airplane variable-pitch propellers in mind. Everything makes sense except the efficiency up to 8 degrees (or 16?) and how that applies to 5" long range propellers with pitches as low as 25. Should we be trying something around 30-35, or even higher? I have ran across people getting surprising efficiency out of very high pitched props.
Can't wait for the Glide analysis, and hoping You can get a Fouride in at some point.
The best efficiency should occur at the best lift to drag ratio of the prop which will depend on shape but is typically around 8 degrees (this is for a hover). Obviously inflow velocity affects the angle of attack so can get a little complicated. Once you start flying the drag of the quad and the inflow velocity due to your forward speed starts to matter. At high forward speeds a steeper pitch prop is probably going to give you more efficiency in g/W.
Hi Chris, this is reallly good.
There is only question regarding AOA. The first diagram showed maximum efficiency at typically 4 degrees and stall at 16 degrees. However later you mentioned that efficiency will be improved all the way up to 16 degrees . Probably I missed something there.
awesome video. I just recently went from a 5135 that came with my nazgul 5 and went to a 5043 and I was noticing I was having trouble getting it to float over things while trying to split s over them andbai could hear it grabbing more in the maneuver this video really helped me understand why it's doing that. What do you think of the really low pitch prop that it came with. When I look them up it says the pitch is 3.5
Good person good answer.
Haha dudes giving me a whole ass physics lesson, when all i wanna know what kinda props fit on my motors. ha.
The video, and many of his other videos are marked with "FPV", however they apply more broadly; namely any fixed pitch electric multirotor. He owns FPV "vehicles" and operates them, and he choses to cover the science behind these vehicles for the benefit of us all. but it should apply wholly to any fixed pitch electric multirotor. Most of his videos probably also apply to some VTOL plane configurations.
Great content! It got me thinking though, what if one would (theoretically) construct a prop that utilizes centrifugal force to alter the pitch slightly? Think of how a CVT system works with weights and ramps/rollers.. Would it be possible? Would there be benefits to reap from doing this? And yeah, it would likely not be suitable for a 5" prop for rigidity and durability reasons.. Maybe this is already a thing, I haven't read anything on the subject, but this video just had me thinking about how it could be done.
I seen you briefly touched on the density of air. I am interested to see what your thoughts are on elevation and prop and pitch adjustments.
Typically the best way to combat elevation is to increase the chord length of the prop blade. Steeper pitch can hurt propwash handling.
Nice! I graduated as a lawyer, am building my first 4inch semi longrange sub 250gr. 4s quad, and after checking motor load charts, making some calculations I've diside to get 1507 2680kv motors with biblades 4024 on a throttle limited around 20% for LR, and 4023 triblades for freestyle.. (haven't seen less pitch im a triblades 4 inch props yet). Hope I'll get parts of it soon to complete, film, test and finaly have enough footage to start my channel.
Ty for your sience, I'll be waiting for your frame, and hope we'll get a affordable shipping cost for it (Russian Pilot in the house 😉)
I'm hopeful that my frame will be globally available at a reasonable price! Good luck with your channel.
Nearly every time I try a new prop I think what a wonderful prop. Everything from a 3" pitch to a 4.9" pitch. I even like the 5.2" pitch but I don't use those because I get about half the flight time. I don't think I'm good enough yet to tell much difference between props.
Hopefully this video has helped you decide what prop to pick for how you like to fly! 😁
I have a cinebot 30 any suggestions for different props mostly recreational flying and I love the science behind what you do koodos to you
give us a cinewhoop already!! for a batteryless gopro >D ... also check the astrorc carbon fly 25 frame ,, diagonal frame.. keep the videos coming!!! and what controller should we use for maximum wall concrete penetration and dont failsafe and available >D
@Chris : Thanks for the useful videos . Wanted to bring up one question on props . Lets say while flying a 5 inch quad we tend to keep stock of multiple props . While all props will usually be 51 series , the pitch could vary . Now while flying lets assume we have a 5143 set on the quad and happen to break one or two of the front facing props . Now the only other set i have is a 5148 set . If we replace the front props with the 5148 does it cause problems . what happens if we end up mixing pitch of props mounted on a quad ? Is this a bad practice or something that never must be done ?
I would really love a video about cinewhoops. The trends are covering the actual data. The Shendrones Squirt is supposed to benefit from a "duct effect" (and I feel like it flies really bad). Everyone is jumping on the "Slammed Squirt" trend and getting rid of the ducts. Who is right ?
Meanwhile, HQprop is making a 6-blade and now 8-blade 3" prop. What's the science behind these choices ? I'm using 6-blade and it feels alright, but it's supposed to be quite inefficient for a quad that already has a big disadvantage in weight to power ratio.
Ducts are on my radar as another topic to apply some science to, I think you are right people need some more information on when and how to best use ducts to get the most from them and when to go with just prop guards.
Perfect! 😀Having both options on the Squirt and on a 3D printed frame, it will be easier to compare them with a bit more knowledge on the physics behind it.
Is the slammed squirt trend actually getting rid of the ducts? still looks like a duct to me, just a bit shorter... Anyhow Rosser has since made the duct video and I have just ordered a slammed squirt, I'm a little concerned that maybe I won't get the actual beneficial effect he described in the video from the slammed version, and maybe I should ask for a regular non slammed version. The slammed version looks nicer though 😅😅
@@definingslawek4731 It is actually different because it doesn't benefit from the "turbine" effect. Chris made a video about it if you want all the details : czcams.com/video/7f2DZIC8a1k/video.html
@@LenordeFPV I'm told the slammed squirt still has ducts, and there's a video showing an increase in thrust with the duct versus without.
Anyhow I ordered a slammed one and I hope that it wasn't the wrong choice vs the non slammed version. In OP's video on cine whoops he says the most interesting part of the ducts is not the extra thrust but how it makes it more stable and thus comfortable for flying slow proximity and Indoors and stuff
Would be great o see real life examples with known props and quads during a test? Great video.
Thanks for the support and the great suggestion. 😁
@@ChrisRosser
Thank you for the content! Next tuning a 7”? :-)
This is very very interesting and confirms and extends much of my own investigations. I have a question: how does the inflow velocity calculation change for fixed wing? Obviously the vin from the airspeed but do you need any additional factor to account for the inwash from the prop of can I just plug in airspeed in m/s?
I think you should be able to calculate inflow velocity using a momentum balance taking into account that the initial airspeed is not 0 as it is for a quad in hover.
I was thinking about this more, do you know if the prop flex has any effect? These fpv props are quite flexible, I presume at a certain disk load the majority of the flex will have occurred and have little impact. I wonder if there is excessive flex at a certain low load threshold.
You have a new subscriber. 👍
It is always a compromise with a props, isn't it? You just can't have great performance in all situations with one selected prop. Unless if you are flying a helicopter, but that's a different topic.
I guess the only thing I still feel curious about; is props based around air density... I.E. how would a high pitch props performance be affected by flying at a mountaintop where air is thin? Also another incredible video mate. Doing the FPV God's work!
At higher altitude the air is thinner so you will get less thrust. I think the best way to combat that without affecting any other parameters would be to use a prop with a longer chord or additional blades. If you change pitch you will affect the stall performance but additional pitch could be another way to get back some of the thrust you're losing due to the thinner air.
I would really appreciate a video relating to altitude. I fly freestyle and long range between 8,000 and 13,000' above sea level. I've enjoyed experimenting, but I also enjoy your videos, science, and experience
Love your content!
I do have a question though: I think I’m comfortable with selecting a good blade count and pitch for a prop, but how would you go about selecting the correct prop size?
I have a video on that! czcams.com/video/zY68Nf9Cobs/video.html
Hello, thank you for the great video! My Question is: What about tiny whoops (e.g. Moblite 7 HDZero 1S). Is there a way to make it more efficient by changing the Gemfan 1610 2-Blatt Propeller?
Thank you, this is great explanation. Now i finally understand why my 700g 5" flies much better on 5.1x5.1x3 than 5x3x2. I watched many videos which blindly suggested to use bi blades for long range, but that was not working for me
Glad I was able to help you!
Another interesting thing to consider would be if "Floppy proppies" have an advantage in response time compared to their fixed counterparts. And if so is it quantifiable?
This explains why I wasn't getting the top end performance for the Ethix peanut butter jelly props. I thought it was the weight, but it's likely my lower KV motors for 4S?
Chris, these slides are available somewhere so we could quickly refer to your graphs when needed?
A blog or server perhaps?
I've put the slides from my last few videos here: drive.google.com/drive/folders/1md9Vc2l-PnY5jVDQSH7HXB_FSh5z8dr_?usp=sharing
If you download them you can watch the embedded videos as well!
Okay I'm late to the game but everyone says you're the man to go to for facts. And I can't really find any good factual information on whether if the stock props or the prop adapters and a different type of aftermarket prop is better on the DJI fpv.?? It just seems like to me if you add the adapters and a lighter smaller prop than it really is being counterproductive and adding a smaller pop to spin off faster... Any advice would be greatly helpful
Hi! Can you help me, what config i should consider for 350g payload for my quad (like gopro as payload), bottom mount, battery on top? Thanks!
Thank you very much for these useful tips! Does the chord length of the prop contribute to the stall point? I noticed that I have a prop with a smaller pitch and larger chord but it seems to be more propwash prone than another with a steeper pitch but smaller chord (for example: emax 2.5x1.9x3 vs azure 2.5x4x3). I often struggle to choose the right propeller because of this. It would be useful to know what pro/cons comes with a larger chord because i think pitch and geometry it's a bit tricky case.
Not really the chord length is much much less impactful than the pitch. A longer chord makes more thrust so you probably have lower rpms with it which will increase propwash. If you have set up dynamic idle that should really help.
@@ChrisRosser Thanks i will try!
Just bought some Gemfan 5051 tri blades for my freestyle drone. They were on sale, I'm new, and I crash a lot 🙃 4s 2450kv 500g quad. I guess I'll set a throttle limit and see how they do!
whats ideal to optimize in-ground effect hover and out-of-ground effect hover?
VIDEO IDEA:
1. Build a "perfect" freestyle 5" quad considering all the technical details (calculations and everything) : motors, props, frame
2. the same but for racing ..
Hi Chris, thank you very much for your teaching....Can you please put, the most common/important prop sizes, into the graph of stator motors volume in relation of inch quads, in order to have a really clear full view of how to pair these Items. Thanks
I know it will be a very general guide, considering all the lots of thing you have just explained. about different direction of the air flows ext ext. Thank you💪
I think that graph is in my motors video
@@ChrisRosser Hi, yes of course, I mean please add also the props, in order to have the exact position of them between stator volume and inch quad. Thanks