# The most important part of your FPV drone. Testing SO MANY 5" Props!

The prop has more of an effect on thrust power, prop wash handling and top speed than almost any other component. That youre going to pick on the drone and not only that its also one of the cheapest and easiest components to change to get very, very different flight performance. In this video im going to test over 20 different props and give you the lowdown on which are the best for freestyle the best for racing and which are ones that i suggest you avoid so lets not waste any more time and lets get right into it. So before we look at the results of my testing, i want to take you, through the test setup that ive used to collect this data. This is the title. Robotics 1585 thrust stand and i think its the ideal tool for testing these five inch. Props, it collects so much data at once that you can just do one test on this piece of equipment and have everything you need to know about. The performance of the prop and motor. The prop ive got set up in a pusher configuration, so the air is being pushed out this way and ive tested it both ways round, and i get much higher thrust. Numbers and efficiency numbers running the prop this way around and i think its because theres just too much material behind the prop blocking the thrust column to get the best performance running it. The other way around the motor that im using is the iflight zing to 1855 kv, and you can see that ive put a piece of white tape on it here and this white tape is for the optical rpm sensor.

So as the motor is spinning, this white tape is passing an optical sensor and every time it passes the sensor, the sensor counts it, and that way it can very, very accurately determine the rpm of the motor and because a prop is fundamentally dependent only on rpm. For the thrust that it produces, you need to get an accurate measure of rpm to understand the performance of the prop moving backwards. Weve got these two load cells here, these two load cells and one back here as well. If you can see that these two load cells measure the torque that the motor is applying to the prop, so we can see how the prop responds to torque and up on the top. Here i have the esc and control board that drive the motor and im using the diatone mamba f50 pro 128k esc to drive this motor and im using my blheli32 recommended settings so thats 24k to buy rpm for the pwm frequency, 16 degree. Timing and 50 ramp up power at the back. Here we have another electronics board and thats measuring the voltage applied to the motor and also the current thats being drawn from the motor as well. It also has an accelerometer on this board, so it can measure the vibration associated with this whole system and thats really handy, because if the prop is slightly out of balance, youll get a lot more vibration of the test stand and you can measure that with the Accelerometer on this board, all of this data is being logged at about 100 times a second for this testing.

So we get lots and lots of data points to compare these props to each other. The whole system is being powered by this 5200 milliamp hour pack and thats being kept chopped up by this benchtop power supply. So the voltage is always constant at 24 volts when it comes to actually running the test im using the automatic control feature of the gui software. That comes with the thrust, stand and im running the same script, every time and thats just ramping the esc power from 5.5 percent, which is a typical idle value for a quad up to a hundred percent, and that test is the same for every prop that i Tested so its time for me to show you what a test looks and sounds like and for this im going to need eye protection and ear protection. So let me put these on and then well run a Music test, all right. So now you know how i got the data lets, take a look at the results and i was pretty surprised – and i think youre going to be too lets start by talking about weight and weight is a really important measurement, because its very closely correlated to the Moment of inertia of the prop and a prop with a larger moment of inertia, is going to be harder for a motor to spin up or slow down, and the result is that the quad is going to be less responsive. The faster that the motor can spin up and slow down the prop the quicker the quad is going to be able to respond in things like prop wash and the more stable and smooth its going to be in the air.

The lightest prop that i tested was this hq 5.1 by 2.5 by 3, very light pitch prop, and the heaviest prop that i tested was this hq r42, which is a prop designed for racing in general. The steeper pitch props tended to weigh more, i think, steeper. Pitched props need to be heavier because they need more material in the prop blade to keep it stiff under the high aerodynamic loads that they face compared to a lighter, pitched prop blade. Manufacturers dont want a steep pitch prop flattening out at high rpms and losing the benefit of that pitch, so they add a bit more material to keep those blades a little bit stiffer, but the result is that the prop ends up a little heavier overall. The next thing i want to talk about is efficiency and before i jump into the table of values, i want to talk about the shape of the efficiency curves for all of these props. So on the y axis, we have the power that they consumed and on the x axis the thrust that they delivered. So anything thats sort of over here is very efficient because its producing a lot of thrust for very little power and anything up here is very inefficient because its producing not very much thrust and its consuming a lot of power. And the thing that i want to call your attention to is the fact that these curves dont really cross over each other as we move up in thrust.

So a prop thats, very inefficient at low thrust is also very inefficient at high thrust and a prop thats. Very efficient at low thrust remains very efficient, all the way up to high thrust. So, if were looking to compare the efficiency of different props, we can pick a point, for example, one kilo of thrust here and look at the efficiency of the props. At that point, and that will give us a good comparison of the overall efficiency of the props across their entire thrust range, so thats what were going to look at now. This is the efficiency of all of the props at 1 000 grams of thrust thats, a good measure. All of the props were able to achieve 1000 grams of thrust, but they all used very different amounts of powers to do it. You can see that the most efficient prop is this hq 5.1 by 2.5 by 3, again so thats coming out top with an efficiency of 2.64 grams per watt and the 3d prop. The hq 3d 5 by 3.5 by 3 is the least efficient by quite a margin, and i think this goes to show that when youre trying to make a 3d prop so a prop that you can run in either direction and produce thrust in either direction, you Really take a hit on the efficiency, thats really significant. What i find particularly interesting, looking at this chart of efficiency, is that there doesnt seem to be much correlation between the pitch of the prop and its efficiency.

You can see that we have some props that a very steep pitch like this dal spitfire thats, still efficient, and we have some props that have a very low pitch like this del cyclone and the j40, but theyre still inefficient props. This goes to show that i think you need to test these props on a thrust stand to understand their efficiency all right. Now we get on to max thrust, and this is like the bench press or deadlift of prop testing right, its just whats, the biggest number that these props can put up, and what we find is that the prop that actually delivers the most thrust in my testing Is this 5.1 by 3.6 by 3, prop from hq, and it puts up over 1600 grams on this iflight zing to 1855 kv motor and down at the bottom? We again have this 3d prop bottom of the charts. It doesnt produce much much thrust, its not very efficient, obviously youre compromising its performance, because you want it to be able to produce thrust in both directions. Other good performers, this nascal f5, that produces plenty of thrust as well as these v1s props by hq the 4.8 and 4.5 also put up good thrust numbers once again, its not as simple as a steeper pitched prop is going to deliver more static thrust than a Lighter pitch prop, we can see here that the two top performers have a relatively modest pitch, 3.6 and 3.

5. I think this goes to show again why thrust and testing of props is so important. You wouldnt know what thrust the props are able to produce just based on their diameter and their pitch. There are five inch props that produce huge amounts of thrust. There are 5.1 inch props that produce. You know relatively little like this dow cyclone down here and you have steep pitch props that produce a lot of thrust, but also shallow pitch props that produce a lot of thrust so its quite difficult to predict the performance of the prop based purely on its diameter And pitch, really, you need to test the prop on a thrust. Stand to know how much static thrust is capable of producing a static thrust test alone. Doesnt tell us everything we need to know about. How prop is going to perform in the air. Props. Have this phenomenon where they deload as the quad accelerates? That means that the amount of thrust that the prop produces at a given rpm reduces the faster the quad is flying through the air. Now there is a parameter which captures that behavior and its called the advanced ratio and the advanced ratio of a prop is the ratio of the free stream. Fluid speed to the propeller tip speed and a larger advanced ratio predicts a higher top speed all else equal. So a larger advanced ratio for a given amount of thrust predicts a higher top speed. Now, how can we calculate advanced ratio for a static thrust test where the free stream fluid speed would be expected to be zero? Well, one way we can do it is by looking at the speed of the air moving through the propeller disk, and we can calculate the speed of that air by looking at the thrust that the propeller produces.

So if we take a momentum balance of the prop, we have the prop producing a certain amount of thrust f for a certain amount of time t and to produce that much thrust, it has to change the momentum of a certain amount of air. So this is this delta mv here now the mass of the air that its changing we can calculate as a cylinder with a length that is the velocity of the air thats moving through and a radius thats, the radius of the prop. So every second, this cylinder of air is moving past. The prop the mass of that cylinder of air can be found by taking its volume, pi, r, squared v, multiplied by the density of air rho, and then the change in momentum. We can assume that all of this air starts off at zero speed, because this is a static thrust test and it ends at the speed v, the velocity of the air moving through the prop. So then, we end up with the thrust being able to be calculated by looking at the density of the air multiplied by the area of the prop disk multiplied by the velocity of air moving through the prop squared, and that allows us to calculate this proxy. For free stream, fluid speed v now its not true free stream, fluid speed, but if we use that proxy value, we can calculate a a sort of advanced ratio for a static test.

Now, if we look at this advanced ratio for all the different props, we can say that a prop with a larger advanced ratio, so prop sitting at the top of this list, is going to deload less as you accelerate through the air as your quad accelerates, and Therefore, is probably going to be able to achieve a higher top speed than a prop with a very low advanced ratio. Now thrust does play into this a little bit, as does prop diameter, as does prop pitch, but what we can see is that the ethics s5 came out with the largest advanced ratio, so this is the prop that i would predict would have a very good top Speed for your quad, whereas if we look down at the bottom, the dow cyclone has a much lower advanced ratio, its about 25 percent less, and so we can see that that prop is going to have a lower top speed its going to deload much more quickly. As the quad accelerates and the amount of thrust its going to be able to produce falls off a lot. What we can see is that the ethics s5, the nascal f5 and the emax avon flow all have really high advance ratios, as does the r42, which is what we would expect for a racing prop where youre wanting to be able to achieve a high top speed. With your racing quad so for racing, quads youre definitely going to be wanting to look at the top of this list to find a prop with a nice high advanced ratio so that you can get up to a nice high top speed on the straights.

If youre. Looking for freestyle performance, advance ratio may be a little less important to you. You may not care about the maximum top speed that your quad can achieve and therefore you may not mind picking a prop with a lower advanced ratio that has other properties that are beneficial for freestyle, like a very light weight or a low pitch thats going to Be resistant to prop wash so up here for racing and probably a little lower, maybe down here for sort of freestyle, low speed type applications. The final property i want to talk about is vibration and vibration is an important parameter for me, because props create a lot of vibration and the more vibration they create the more they affect your ability to tune, your quad, so the more vibration your quad has, the More filtering youre going to need to apply which increases delay on the pid loop and youre. Not going to be able to push your d gains up as high without getting hot motors and thats going to affect the responsiveness to the quad and prop wash handling. And things like that, so having a prop with low vibration, means that the prop has been really well balanced out of the factory and so as its spinning its not generating much vibration at all. You can see here up at the top. We have some really good performers and theyre producing less than half a g of vibration at 20, 000 rpm and then the worst performers are producing a little bit more vibration, and some like this, dow spitfire and the azure power are producing really quite a lot of Vibration, getting up for one g or even more than one so thats gon na affect your ability to tune the quad, because twice the vibration from the prop is another.

You know 3 db of noise on the gyro that youre going to need to filter out. So just worth bearing in mind props with low vibration are going to help with tuning now its time for the conclusions, but before we find out, which prop is best for freestyle and which prop is best for racing based on this testing its time for a sponsor Slot and that sponsor, is you guys, because i havent got a sponsor slot for this video? I didnt get any sponsorship to make this video. I bought all the props myself, so if you would like to support the work that im doing id really appreciate it, if you check out my patreon, you can join for just a few dollars a month and itll give you sneak peaks of all the work that Im doing and also help me make more videos like this to support all of us in the community of fpv. So id really appreciate it. If you check that out, but now time for the conclusions to be objective about the conclusions, ive given each of the props a ranking on each of the parameters so for weight, ive, given the number one rank to the lightest prop for efficiency ive, given the number One rank to the most efficient prop for thrust ive, given the number one rank to the prop that produced the most thrust and for advanced ratio ive, given a rank for the prop, with the largest advanced ratio that gets ranked number one and for vibration.

The prop that produced the least vibration gets the number one rank and then to calculate a total for the ranks ive just taken. The average rank that the prop gets across all parameters now for this table, ive not included the advanced ratio in the ranking, because you dont necessarily want to prop with a large advanced ratio. Sometimes a prop with a smaller advance ratio is actually going to be better for things like freestyle, so for freestyle. I think that the best prop in my testing was the hq 5.1 by 2.5 by 3, because overall, it was the lightest it had the best efficiency. It was middle of the road in terms of thrust and it had one of the best vibration numbers. So overall, it gets a rank of 4.3. The worst prop for freestyle is the hq 3d prop, and you know we talked about it before you do compromise performance to have that ability to run the prop in both directions and get thrust in either direction. So to make it symmetric in that way, you do sacrifice some performance, but you can see the list here of all of the props and how they perform on each of the ranks. So you can always pause the video and have a look at the prop that youre interested in and see how it compares to the others on any of the parameters. If we now look at the ranking with advanced ratio included – and we say that actually we do care about having a prop with a large advanced ratio, because top speed is important to us, for example, for racing or just for flying faster.

Then we can see that that does change the order quite a bit, and the nazcal f5 comes out as the best performer across all of the different parameters, with an average rank of 5.2 and the hqdp v1s prop 4.3 inch pitch also comes out really well, and We see that the 5.1 by 2.5 by 3 still comes out pretty well, but obviously its got a very poor ranking in terms of advance ratio, because its got that very shallow pitch, and so it drops down the order a little bit. Obviously, if you weight the factors differently, this is just an average weighting, but if you weight advance ratio really highly, then you can go and look at the something like the fx s5, which has the best advanced ratio. And if you really care about maximum thrust, you can go and look at something like this 5.1 by 3.6 by 3, which gets the best thrust rating. So its really up to you how you use this data to choose, which prop is right for you, so there we have it im, definitely going to be trying out these 5.1 by 2.5 by 3 props from hq on my freestyle chord, because i was really impressed With how well they performed and honestly i dont really care about top speed for my freestyle flying and these iflight nasgool f5 props a great all rounder. It would seem so good for anything freestyle racing. Let me know down in the comments what you think of the data theres going to be links down in the video description to a spreadsheet, with all this information, so you can sort it look through it at your leisure.

Take your time and figure out. What prop is going to be right for what you want to do? I hope youve enjoyed the video if you have hit the like button. If you want to see more subscribe and if you want to go the extra mile and support more work like this theres, always patreon thats all i have for you for today, so until next time.