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.

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.

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.

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!

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!

Some great content dude

Love this, Looking forward to the next load of knowledge you can share with us. Keep it up !!

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.

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!!

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

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.

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

G'WeekenD Mr. Thanks 4 everything U do 4 this great community. I really enjoy your content, takeCare mate

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

Thank you for sharing so useful information! Keep on going!

Best FPV video I have ever seen, beats even JB in my opninion. Do more please!!

Brilliant! I really like the academic approach! Well done!

*Chris Rosser* 💯 🏆 🥇 Щиро дякую за просвітницьку 🧑‍🔧🔬🧠✨ діяльність, дуже корисно!

Excellent work. Very informative video. Keep it up

your videos pushed me to the other side of peak on dunning-kruger curve. thank you.

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 !!

This video was fantastic. Thank you for doing this.

So detailed and complete, I love it!

I learned something today! Great video, thanks for uploading!

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

Damn. You posted this just after I passed my canadian rpas exam. Stall mechanics was one of the questions!

dude you are my new favorite person, thank you!

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.

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!

The man Chris does it once more...outstanding vid bruh

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 content for some one luke me who wants to understand everything thanks Chris !

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

thanks Chris, very informative content

Thank you this helps tremendously!! Your'e video's are very educational I appreciate the knowledge!

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

Great info. Thank you!

thanks the video clarified what prop should I use thanks a lot

As a scientist and also a pilot... FOUR THUMBS UP for you my man

The moral of the story is that 5043 props are all that you ever need as it seems to strike the ideal balance.

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!

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

very well done video. i like the maths and thinking.... bravo!!!!

This justifies my findings in my prop reviews.

Very informative videos.

The high pitch for lr was a big ah ha momemnt for me. Thanks man.

Again a really good video!

Awesome information Sir

Very useful, thanks!

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.

Really good information thanks 👍😎

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.

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.

As a fellow aero engineer, great presentation.

Great content.

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.

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.

(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.

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!

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 😁

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?

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.

yes excelent video thank u.

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 ;)

Scientific approach which i like.

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 😉)

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

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?

@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 ?

Awesome

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!

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.

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?

Its really helping

Would be great o see real life examples with known props and quads during a test? Great video.

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 think some useful oversimplification would be possible just in comparing chord profile, and what the relative pitch across that profile is going form the hub to tip. It's impressive that all of the most recent props have converged on roughly the same chord profile (with varying amounts of leading edge sweep) as a trade between durability and in-air performance, and the 'best' of the latest units all share reduced chord that helps lower rotational moment without results in a frail edge of the prop, and I think that's why the propwash response is so good (compared to back in the day when we were flying bullnose props).

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.

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?

Thanks.

I’ve had a couple of questions regarding props. 1. How much of an adjustment should we consider for different altitudes? I’m in the Rocky Mountain region, which is about 4000ft above sea level. 2. How can we tell if a prop is killing battery performance? Is there more to consider than a drop in flight times? I guess I’m looking for some general rules to apply to a 5” 6s low-kv freestyle setup. I’ll give it some thought, revisit, and try the math. Thanks for the info. I’ve been curious about the subject.

thumbs up new sub, thanks for sharing

Thanks - helpfull

Hey Chris - I know this might be semantic but I think it is an important distinction when talking about the dynamics of our kwads. I thought that the prop generates lift and the portion of that lift that provides forward motion is thrust? So wouldn't the specific airfoil and angle of incidence change the how much thrust is generated? I thought, Angle of attack is generally in reference to the prop where angle of incidence is relative to the craft's attitude of a specific axis. Additionally, I think the use of certain generalizations is a slippery slope. Also I have a question regarding the V(inflow), I don't think it always has to be axially aligned - but the angle should be a known value for calculation.

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?

Hi, I asked myself all the time how to think about this on my Cinewhoop. I just finished watching your new video about ducts, and I have a squirt V2 at home. Also I am just designing my own "megas-quirt", that can handle 3.5" (89mm) props, as my Squirt is barely holding itself in the air with a Hero 8 and a 1300mAh 4s lipo. Now to my question: How do you think that multiple blades change the therory. By that I mean the 6- or 8-bladed HQ props, or the much steeper Gemfan D76 or sth like this. My testing tells me, that two props that both are called to have a pitch of 3 aren't really comparable, doesnt matter whitch size (3", 5", ...). In the cinewhoop-part also the diffrent blade-count makes everything even more uncompareable. I really have problems to compare a Gemfan D90 (3 bladed prop, pitch "3") to a HQ 89mmX8 (also pitch of "3") but they clearly are diffrent in their steppness-angle and will poth have very diffrent thrust. toothpick-class: Gemfan for example has a 3018-2 prop (biblade) and a 3016-3 (triblade), I also cant tell in this case which prop I could expect to have more thrust. The issue is, that we often dont have real numbers to calculate with or alternatively have simulation-values or static-bench test from the manufacture himself (1st hand). Sometimes I have the feeling, the manufacuters dont use the pitch-value to tell us how steep the balde is, rather to tell how much thrust they think the prop makes compared to their other props on the market. By adjusting the pitch value they use for marketing so they can put their props in somewhat of an order they make comparison for us pretty rough, and practically impossible to compare to other companies. Did/Do you think/feel the same as I do, or do you understand my problem? If so, do you have any idea how we could interpret these values we get from the manufactures, or do anything about it other than just buying a ton of props just to find out that 99% arent the ones we where looking for? Thank you so much for your videos, it is great to understand such topics in greater detail, love it, keep it up!

Chris, these slides are available somewhere so we could quickly refer to your graphs when needed? A blog or server perhaps?

Hi Chris, what is the effect of pitch and efficency vs number of blades? I guess a lower pitch creates less turbulences which affect the next propblade and probably decrease less the effiency compared to a prop with higher pitch blade. I expect not a dramatic effect, but I think the question is interessting, if low pitch props are loosing less effiency with more propbaldes over high pitch props with more propblades. Also your recommendations of Longrange props brings up a question: on 4"LR you see mosten low pitch props like 4024. The Reason is the amound of amps, LI-Ions can`t provide much amps, so there is also an electrical tradeoff of pitch vs amount of amps which can be delivered from a Li.Ion pack. So where is the sweetspot of pitch vs. amps?

In terms of emptying the reservoir of vibration in the frame it seems like the battery pad would have the largest influence considering its holding an isolated mass that's about 1/3 the total quad weight. In my case the under mounted battery has a sticky pad connected directly to a carbon surface that also mounts to the flight controller. I wonder if rubberized pads have a high Spring rate that could create harmonic frequencies... Versus gel or soft foam.

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

Hi please what about cinematic 5 inch what props i choose? Thank u so much

Hi, it sounds like it would be helpful to set dynamic idle (dyn_idle_min_rpm) in betaflight to just above the stall speed of a given prop. I would love to learn how to determine this setpoint.

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.

What’s your take on the low-pitch HQ R38 props popular for 5” racing? Subjectively I’ve found I prefer these props to higher-pitched props, but perhaps it’s just because the reduction in trust translates to more control?

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?

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

And also a question. My predictions were about correct. I want to build a lighter freestyler quad very soon. I picked up 2207 1950kv motors, with 5130 props. I am doing an auw calculation soon, so I could add that info here too if needed, but I want to ask: Would this be a good or bad setup from the calculation and performance perspective? I don't want to make a dud quad, and I've never really bothered with these calculations, if you could help me out, would be greatly appreciated!

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.

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.