I am passionate about building and flying scratch built foam park jets and passing on my experiences and lessons learned from more than five years of experience. Blog is purely based on my own opinions and experiences. If you have questions, please e-mail me at scott.parkjet@gmail.com. Park Jet noise...the "other" sound of freedom :) Happy flying! Cheers, Scott
Showing posts with label EMAX RS2306 2750 Kv motor. Show all posts
Showing posts with label EMAX RS2306 2750 Kv motor. Show all posts
I received a couple of Tattu R-Line 1550 4S 75C batteries in the mail a couple days ago to experiment with some serious speed in my park jets😀
These batteries have a very good reputation from what I have read and watched on YouTube, they were not cheap, but I only bought a couple for some experimentation and serious speed fun!
I went with this small size as I didn't want to pay a big weight penalty, so even though my flights will be short, they should be fast😉 The batteries weigh 186 gr/6.6 oz. The normal 2200 3S batteries I use weigh 192 gr/6.8 oz, so my planes should still be pretty light to help them be fast.
I already did some quick testing for a modified RC Powers Su-30 V4 I am building specifically for speed. Here is a short video I shot discussing this testing. You can watch more about this special build by going to this playlist on my YouTube channel.
As discussed in the video, the only successful test was with the EMAX RS2306 2750 kv motor using the 6x3 EMP prop and the HobbyWing Platinum PRO 40A ESC with custom settings of 26.25 degrees timing and 8 KHz PWM frequency. You can see the full details on my motor test spreadsheet, but here are the numbers for the combo I mentioned with this new Tattu 4S battery.
50% throttle - 21.8A/346.5W producing 940 gr/33.2 oz of thrust;
100% throttle - 54.8A/860.2W producing 1630 gr/57.5 oz of thrust.
WOW! That is a 45% increase in thrust over the best mid range power on 3S and 36% increase at full throttle!😲
Until my 5" props that I have ordered show up, this is the setup I will experiment with.
Here are the 5" props I have ordered based on watching rcplanepirate's video on his testing of the EMAX RS2306 2750 kv motor and his personal recommendations. I pasted this list in from the comments of this video.
I managed to get another round of bench testing done with the Turnigy AE-45A ESC today using the EMAX RS2306 2750 Kv motor. This testing provided some very "educational" results😊
You can read the full details here on my motor test spreadsheet, if you look along the bottom, you will find tabs for each motor. All the data below is based on using the 6x4 APC gas prop and Gens Ace 2200 3S 45C battery, links for both of these is on the spreadsheet.
Thus far, the higher Kv motors seem to like 24 KHz PWM frequency for improved mid range power, but I did one quick test with factory defaults for the AE-45 just for reference.
AE-45A ESC Timing 15 degrees, 12 KHz PWM frequency (default)
50% throttle - 13.5A/163.1W producing 530 gr/18.7 oz of thrust;
100% throttle - 37.4A/427.9W producing 965 gr/34 oz of thrust.
Thus far, I have tested this motor with the 6x4 APC gas prop on three different ESCs, the Turnigy Plush 40A, HobbyWing Platinum PRO 40A and now the Turnigy AE-45A. From the spreadsheet, here is the performance data listed from lowest to highest. Both the HobbyWing and AE-45 have custom settings, the Plush is at factory default.
Turnigy AE-45A Timing 22.5 degrees, 24 KHz PWM frequency
50% throttle - 17.2A/206.2W producing 610 gr/21.5 oz of thrust;
100% throttle - 39.7A/451.3W producing 1005 gr/35.5 oz of thrust.
Turnigy Plush Timing low (factory default)
50% throttle - 17.2A/206.7W producing 620 gr/21.9 oz of thrust;
100% throttle - 38.4A/435.7W producing 1040 gr/36.7 oz of thrust.
HobbyWing Platinum PRO Timing 26.25 degrees, 8 KHz PWM frequency
50% throttle - 16.7A/201.6W producing 647 gr/22.8 oz of thrust;
100% throttle - 42.6A/507.1W producing 1075 gr/37.9 oz of thrust.
So the HobbyWing amps at full throttle is greater than the base rating for the ESC which I don't normally like to exceed (although it does have a 60A burst), so I will proceed with caution. I have flown with this prop/motor/ESC combo in cooler weather already and the ESC was a bit warm, so in the summer I might have to be more cautious, find a different setting or use the Plush, more field testing required.😀
So what seems to be interesting as I collect more data with the Turnigy AE-45 and the HobbyWing and experiment with timing and PWM, none of the motors tested thus far performed well at 12 KHz PWM frequency except perhaps the 2212/6 2200 Kv, but I have to more testing with that motor. As soon as I switched from 12 to 8 in the case of the HobbyWing or 24 in the case of the Turnigy AE, the 50% throttle power jumped significantly on the quad racing motors tested thus far. The full throttle performance seems to be improved more significantly with the HobbyWing ESC with motors rated at 2700 Kv or more. The performance with the one motor below 2600 Kv, the Racerstar BR2406 2600 was slightly better with the Turnigy AE and it certainly had the best mid range performance with that ESC.
So I am not going to draw any conclusions just yet until I get some more data collected both on the bench and at the field. However, by taking the time to experiment with the different performance settings in the HobbyWing and AE-45 ESCs, even if only by a small amount, it appears I may be able to optimize the performance of several motors over the Turnigy Plush. Not that I am going to replace all my Plush ESCs and I have to remember that I am using V3.1, perhaps the V4.2 that Hobby King sells now has better performance. I may have to pick one up and experiment😉
Late edit: Primarily because the curiosity was killing me, I put the 2212/6 2200 Kv motor on the test stand, 6x4 APC gas prop, Gens Ace 2200 3S 45C battery. I had tested this motor with the AE-45A ESC on the bench and in the air with default settings and it gives the best power to this inexpensive motor thus far. So I left the timing at 15 degrees and switched the PWM frequency to 24 KHz.
As you can see on the motor spreadsheet, I gained about 20 gr of thrust at 50% throttle, but lost 20 gr of thrust at full throttle compared to default settings. Quite honestly, since this is a pretty "torquey" motor to begin with, for simplicity I would probably just keep the default settings on the AE-45 ESC for use with the 2212/6 2200 Kv motor😊
I had my thrust stand out today doing another round of testing, this time with the EMAX RS2306 2750 Kv motor which is by a narrow margin the most powerful quad racing motor I have tested thus far😊 It is the motor I have been running in my RC Powers T50 V5 for the last couple weeks.
All tests were done using the Gens Ace 2200 3S 45C battery. The timing on the Turnigy Plush is at low (factory default), the HobbyWing ESC is set at 26.25 degrees and PWM (pulse width modulation frequency) is set at 8KHz. These are not factory defaults, you can read more about my previous experimentation with the HobbyWing ESC in this blog post.
This motor definitely likes the HobbyWing ESC with the settings I have set, it has marked improvement at 50% and full throttle with all three props compared to their performance with the Turnigy Plush.😀
The overall best combination proved to be the 6x4 KMP prop with the HobbyWing ESC. Numbers are below (you can also read the full details on my motor spreadsheet).
50% throttle - 18.3A/219.4W producing 635 gr/22.4 oz of thrust; and
100% throttle - 41.6A/482.7W producing 1120 gr/39.5 oz of thrust.
This is where it becomes a bit puzzling, as the numbers with the 6x4 APC electric knock off from Hobby King are nearly identical, same top end thrust, just 5 gr less at 50% throttle. The 6x4 APC gas prop with the HobbyWing ESC produced 1075 gr/37.9 oz of thrust😕 Still decent numbers, but the 6x4 APC gas prop pulls 42.6A to produce less thrust in this situation, so a bit puzzling after the 6x4 APC gas prop performing so well for me to date.
Some of these amp number exceed 40, but this ESC has a 60A burst rating and normally, in the air the rule of thumb is that there will be about a 25% drop in amp draw, so 42.6A would become about 32A. I will check the ESC regularly for heat build up. According to the HobbyKing website, the EMAX RS2306 2750 Kv motor should be able to handle up to 58A if you click on the "Product Specifications" tab when you open the link to the motor.
The best prop with the Turnigy Plush ESC turned out again to be the 6x4 KMP prop, then the 6x4 APC electric, then the 6x4 APC gas. So comparing my results with rcplanepirate's, the main difference is my stand tests in a "puller" configuration, perhaps in the air with a "pusher", the 6x4 APC electric won't perform as well or differently? I certainly know from testing it with several other motors with the Plush ESC at the field, the 6x4 APC gas has proven to be a very good performer in the air. Only one way to find out, so time to put the motor back in my T50, put the HobbyWing ESC in there and get it out to the field with all three props and see what is what😀 The 6x4 APC electric and 6x4 KMP are certainly louder than the 6x4 APC gas prop, so time for a "fly off"😉
I had this beauty out again yesterday for a bunch more fun😀 I didn't shoot any video of yesterday's session as much of what I was experimenting with required that I fly the plane quite high, so not too exciting😐
I now have 43 flights on this little beauty over three flight sessions and have it and myself really dialed in now😎 With a new plane, especially a fairly high performance one like this T50 with which I am not that familiar, it sometimes takes me a little longer to be fully comfortable with it's behaviors and performance. In other words I need to get myself "dialed in" somewhat as well😉 I think I am pretty much in sync with this plane now😊
I did end up sliding the battery back about another 1/4", this didn't really affect my CG or balance point by much, just gave me a better feel on the sticks as it felt just the tiniest bit nose heavy. Like most things, I think it is just a personal feel that can only be determined as the number of flights increases. Things are nice and tight around the CG now in the battery bay.
From the front of the 2200 3S battery to the tip of the motor nut measures 8.5"/216 mm, not including the rudder servos which are behind the prop slot, essentially the largest amount of plane weight (battery, ESC, motor, receiver, aileron and elevon servos) are located in this distance. These roughly add up to 323 gr/11.4 oz. Given that the AUW of the plane with battery is 552 gr/19.5 oz and the plane measured from the tip of the nose to the tip of the "booms" on the elevons is 37.5"/953.5 mm, this means that 58% of the weight is located within about 23% of the plane's length. This is pretty impressive and probably contributes to how quick this plane changes direction in the pitch and roll.
I did decide to experiment with flaps yesterday to see how they would impact slow flight stability and also in shortening landing approach (kind of like a speed brake effect) and allow for softer landing. I know it seems counter intuitive to buy a Ferrari and then drive it around in second gear😏, but I like to know where the limits are with my planes, especially an air frame like the T50 with which I am not that familiar.
I had to play around with the deflection a bit, starting fairly high at about 5/8" deflection which was too much and found that about 1/2" deflection was adequate. Not so much for slow flying, but for approach and landing. Here is a picture of my flaps deflected.
I have my transmitter set up so that they deploy relatively slowly, it takes 2 seconds from the time I flip the switch until they are fully deployed. I find this easier to handle than the flaps snapping down immediately. I had also wanted to see what sort of high alpha I might be able to get out of this plane.
So high alpha was a bit of a bust, when the plane was very slow, any more than about 30 degrees AOA (angle of attack) and wing rock came on or the plane just kind of sat there not knowing what to do with itself until it just yawed and rolled unpredictably. I fear that because I trimmed the rudders down by about 25% from stock that I also did not really have the best rudder authority for high alpha steering. This isn't a real disappointment, I don't fly a lot of high alpha anyway and I built this plane as a "speedster", a role which it fits quite well.
So I then just flew around slowly, seeing how slow I could get and still attempt relatively flat turns without issue using mostly rudder and occasionally a bit of roll input. I could get the plane a little bit slower with flaps than without, but when it hit that point of stall, adverse yaw, tip stalls or other adverse behaviors came on unpredictably and aggressively. Fortunately I experimented with all this above 100 ft so I had time to recover. If I did any of this at 50 ft or less, I fear I would have been doing a "walk of shame" to pick up whatever remained of my plane😬 It took about 50 ft of altitude to recover from these tip stalls and adverse yaw as I had to let speed build up a bit so that I could get control authority to fly out of the situation.
So lesson learned or relearned, don't fly this plane slow😀 It just isn't happy there and unless I like watching my plane throw "temper tantrums" by putting into situations where it isn't happy, not something I will experiment with anymore😉
As my runway is about 650 ft long, shortening my landing approach is not really something I need to worry about, if I cana't land my park jet in that much runway, I probably need to find another hobby!😲 The flaps did work well as "speed brakes" when experimenting with them on landing, although they did cause the nose to want to drop about 30 degrees without applying any up elevator. It shortened my landing approach on average about 30% and did make the landings softer, but I actually found the approach to be smoother without flaps than with them. Also, if I got a little aggressive with the elevator on approach, with the added drag, the nose would pitch up much more than I wanted and the plane would almost stall. If it was something I really wanted to mess around with, I could mix in some up elevator when the flaps deploy, but I don't think I'll bother. It was just fun to experiment😊
So next up I think will be a "flyoff" with the F-22 V5. I have another EMAX RS2306 2750 Kv motor on the way which will get put into the F-22 so that the power setups will be equal and it will be fun to compare them😊
I managed to get this beauty out yesterday for it's maiden flight and to start getting it dialed in😀
I managed to get 10 solid flights done yesterday and think I have the CG dialed in pretty much where I want it and the throws are also just about there as well.
Here is some flight footage and discussion of yesterday's flight session, I did some more dialing in after I shot the video which I will discuss later in this post.
Center of gravity (CG)
As I mention at about 7:40 in the video, my CG ended up about 1/2" ahead of the middle of the black rectangle that RC Powers puts on their V5 plans. Here is a picture of what the CG spectrum looks like on the V5 plans.
Where the toothpick is on my plane shows where the center of this black rectangle is located and the "T" pin shows where my CG ended up for best balance, this has been a trend on all the RC Powers V5 planes I have built😕
Before I go any further on discussing the plane's flight characteristics, I will get the discussion on what I did wrong with my KF airfoils out of the way first.😉
As mentioned in the video, on the first couple flights, the plane felt quite twitchy and as it accelerated or slowed down, often the left wing would dip quite aggressively and the nose would pull left, just a bit scary!😲
I had quite a bit of left trim in at the time, but that shouldn't have caused the rather aggressive wing dips and yaw that I was seeing, so after the second flight I decided to double check that the trailing edges of my KF4 airfoils on both wings were even. Low and behold, the trailing edge on the bottom KF on the left wing was about 1.5-2mm further back than the one on the top...OOOPs! 😬
How I determine this is I push a pin through the wing right at the trailing edge of the KF as you can see in the picture to see if the trailing edges are aligned. When I pushed it through on the left wing, there was foam behind it on the bottom, you can see the part I trimmed off laying on the wing.
Once this was trimmed off, the nasty tendency to want to dip the left wing went away, fortunately the RC Gods were with me yesterday and I didn't lose the plane due to my inattention to detail in that part of my build😳 Big lesson learned and wake up call😓
Control surface throws
A couple flights after I shot the video, I did zero out all the trim on my control surfaces and found that my right aileron was deflected up about 2 mm when it should have been dead center, so I zeroed that and it helped me remove quite a bit of the left trim I had been flying with. There is still some there, but not anywhere near as much.
Here are my current throws which may get adjusted minimally as I get more used to the plane, but these seem to work best for scale flying and still allow me a little extra in the pitch if I need to avoid hitting something😲 Of note, I don't fly with a lot of expo, only 15% in the pitch and roll and 20% in the yaw, so the control surfaces react pretty quickly when I move the sticks. Pictures are below showing where I hold the ruler to measure for reference.
Pitch - 3/4" of travel one way;
Roll - 1/2" of travel one way in both the elevons and ailerons; and
Rudders - 1 and 1/2" one way.
Of note, the travel in the roll in the ailerons and elevons is equal. On most other planes, my aileron throw is considerably less (normally less than 50%) than my elevon throw in the roll axis. With these stealth style park jets, I find I need to have them closer to the same to get the rolls crisp and axial otherwise the rolls tend to be more of a barrel roll or the nose wanders around during the roll.
Launch
Launches were uneventful, I was a bit worried after downsizing and reshaping the vertical stabs and shortening the nacelles that I might have some torque roll issues, but none ever showed up. With the good mid range power of the EMAX RS2306 2750 Kv motor and the fact the plane is pretty light at 552 gr/19.5 oz, 50% throttle was sufficient to get it going and flying away nicely.
Turns
The T50 tracks really well in turns, in the calm wind conditions I had, I never really had to feed in any rudder input to keep the nose tracking true. However, it took me awhile to get the throws and my touch just right to keep it from "over banking". As I mention in the video, the battery sits up much closer to the wing plate, there is only about 3/4" between the bottom of the wing plate and the bottom of the electronics bay on this plane whereas with my modified F-22 V5, it is more like 1 and 1/4" which makes the F-22 more stable. Also, because I reduced the height of the nacelles, there is less resistance in the roll axis, so it sometimes wants to bank a little more quickly than a lot of other planes I fly. However, with time my thumbs will figure out the right touch😉
Rolls
As mentioned above in the section on throws, it did take me awhile to get the rolls sorted out to ensure they were balanced and axial. The T50 is very responsive in the roll axis and requires very little surface deflection to do a complete aileron roll.
Loops
As I mentioned briefly in the video, it takes a little gentler touch over the top of loops to let the up elevator input off at the right time. Since the battery does sit a little high in relation to the wing plate, the T50 is almost a bit "top heavy", so as it starts to go through pure vertical, it can fall over on it's back a little more quickly than some other planes, so when I was trying to go for a nice uniform loop, I had to be careful with this. Otherwise, the loop would look more like an egg where the plane went over the top too quickly and then the bottom of the loop would be wider.
Yaw response
Even though I did trim the rudder surfaces down quite a bit to accommodate my mod to the nacelles, they are still pretty responsive, of course I have pretty big deflection in them, but for keeping the nose true in turns, etc they do the job just fine. I like to pull up in the straight vertical and do stall turns to see how the rudders respond, thus far the T50 is not quite as quick in the yaw axis in a stall turn as the F22, but I can still get it to do pretty decent stall turns.
Slow speed
I took the plane up to about 100 ft a couple of times and reduced the throttle down to about 40% or so, it was not too bad, I had to be very careful in the turns or I would see adverse yaw on occasion. Essentially what would happen is I would be putting in control inputs to make a gentle turn in one direction and if the speed bled off too much, the plane would have a tendency to yaw in the opposite direction of the turn, sometimes quite aggressively. This was not a surprise as it is a common tendency with park jets with the stealth type wing like the F-22 and T-50. So lesson learned, don't get too slow in turns, speed management is crucial to ensure either the plane doesn't want to roll on it's back to suddenly yaw opposite to the direction of turn.
Cruising around
In the video I mentioned that this airframe style (T-50) likes to go fast. I didn't mean you need to fly it wide open all the time, it flies and behaves just fine at about 50-60% throttle all day long, but on occasion as the speed bleeds off too quickly or the throttle setting gets too low other than when coming in to land, it can misbehave somewhat😏
High speed
I would say RC Powers is correct in billing the T-50 as being faster than the F-22. The F-22 is pretty fast, but this T-50 is noticeably faster. Once I got the KF problem sorted out, it handled aggressive acceleration and full throttle runs just fine, I didn't see any torque roll, speed wobble or tendency to want to zoom or dive. Full throttle turns and aggressive vertical pulls were just fine, no bad tendencies, it felt locked in and solid at speed and the wing was strong, no flex even in high G turns or pulling out from loops and dives.
Glide/landing
The T-50 behaved itself well on approach to land, I did my normal approach routine, roll it out straight and level, chop the power and let it glide down at it's own rate from about six ft off the ground, feeding in a little bit of up elevator as needed. Once I had it balanced, it actually maintained a pretty steady and smooth rate of descent on it's own once the power was chopped. I fly with my brake off on my ESC, so the prop free spins as it is gliding, I have found this to give me the most stability. Then just as it started to break ground effect about 2 ft off the ground, I fed in just enough elevator to hold it off and it landed pretty smoothly on it's own. Once I fixed the KF problem I didn't notice any tendency for it to want to tip stall as it slowed down to land, which is good👍
So overall, the T-50 is fast, agile and very responsive, especially in the pitch and roll. Once I started to get the hang of it, it became more and more fun to fly with each flight although it did take a bit more dialing in than some other planes to get the CG and control throws just right. As I mentioned in the video, because of it's quickness, speed, adverse yaw habits if too slow in a turn and it's slight "top heaviness", I would not recommend this for a starter or even second park jet. Perhaps if your skills were coming along well or you had lots of flying experience before getting into park jets it might be a different story. I would say the F-22 is a bit more forgiving while still quick and aerobatic, so if you have never flown a stealth style park jet before, I would suggest flying the F-22 first perhaps with some of the mods I made as discussed in this video to help with stability.
Looking forward to many more flights with this little rocket of a park jet and as I get it dialed in completely and more comfortable with it, I will shoot some more video😊
One modified RC Powers T-50 V5 ready to "slip the surly bonds of earth"😊
I may have mentioned in a previous post that I was thinking of doing the black, white and grey Arctic camo scheme like I have on my test bed Mig-35B, but I decided to go with a "blue" theme this time for something different. I think it turned out OK, either I thinned the paint too much or the Minwax treatment on the DTF where the paper is didn't allow for terribly good paint coverage. No matter, I could put another coat of paint on, but that would add weight. I'm more worried about how it looks at 200 ft away (to help my poor old 56 yr old eyeglass assisted MK 1 eyeballs keep track of it😒) than how it looks at 2 ft away😉
My AUW with 2200 3S battery is pretty good, 552 gr/19.5 oz, so I think it should be pretty light and quick. I decided to put the EMAX RS2306 2750 Kv motor in this plane as it is billed as being pretty fast according to RC Powers, so I might as well give it the motor it deserves😉. I will run a 6x4 APC prop and 40A ESC.
I mounted my rudder servos in the back first so that I could then run the rudder servo wire outside the prop slot and then back in through the hole where the elevon servo is mounted. This will ensure no possible interference with the prop by the rudder servo wires.
As I discussed in my servo video, the wires on the 5 gr servos aren't very long, so since I use a "Y" harness to connect my servos to the receiver, I ran the two Y leads out from the electronics bay so that I could connect the rudder servos, then tacked everything down with a bit of hot glue, including making sure the rudder servo leads were secure in the Y harness plugs.
I decided to trim a bit off the rudders themselves as when it was sitting on the table, these were completely flat on the surface, so by putting a slight angle on them, hopefully this won't cause such an abrupt landing as I flare it in. I probably trimmed about 1/4" off the back and then angled it down to the rudder hinge line.
For durability, I always spread a very thin layer of glue (this glue which is identical to BSI Foam Cure) on the nacelles and along the bottom of the nose. It dries light, clear and hard like epoxy, but doesn't turn yellow over time like epoxy does. Fortunately, I can get this at a local dollar store and it is much cheaper than Foam Cure.
A bit hard to see the glue in this picture, but where it is shiny shows the glue. I darkened this with black magic marker first to help with orientation.
I put a thin layer on the bottom of the nose forward of the small air vent. Since the T-50 doesn't have a lot of nose clearance off the ground (especially since I lowered the nacelles by 7 mm), I suspect occassionally on landing it may tilt forward as it comes to a stop. This glue will help the foam from getting gouged and torn.
Although I won't know how the build and my modifications turned out until I get a chance to fly it, I'm quite pleased with how it looks and with my final flying weight, I think with the fairly low profile it will be a pretty speedy little beast. More to come as I get it in the air and start putting it through it's paces.😊
The postman brought me another package today, some EMAX AVAN-R 5065 3 blade quad racing props. I have titled this blog post as a "discussion" more than anything else as you will see later when I start reporting the bench performance on 3S, I don't think these props will find their way into any of my park jets😐 However, I thought I would discuss them anyway as a matter of a lesson learned, I'm sure I can find someone at my field to take them off my hands unless I do experiment with a 4S setup in the future😏
Banggood did package them up nicely with lots of foam wrapped around the package as you can see above. Below, you see that you get 4 props, two CW and two CCW as you would expect for a quad copter along with more EMAX stickers😊
So a bit of background on why I purchased these props, they were $4.29 USD for the pack of four from Banggood and my research had indicated these props were specifically designed for use on the EMAX RS2306 2750 Kv motor which thus far has been the top performer of all the quad racing motors I tested. I had tested a Gemfan 6x4x3 quad prop on the 2212/6 2200 Kv "workhorse" motor in the past, it generated incredible thrust on the bench (34.9A drawn producing 1039 gr/36.7 oz of thrust), but the blades were too big and created quite a bit of drag in the air. I had hoped that with a smaller blade but higher pitch, I might see some better results.
The prop certainly has an interesting blade shape with almost a bit of a "winglet" at the tip. I put each of the props on the balancer and they were perfectly balanced right out of the package.
I had a bit of trepidation about mounting the prop "upside down" for use in a park jet due to the blade shape and these fears were proven correct. I had to place an old spacer ring from a 6x4 APC prop to keep the blade off the flat top of the motor and as you can see in one of the pictures below it was still a very snug fit while still allowing enough thread on the shaft exposed to secure the prop to the motor.
In this picture, it looks like the prop is still resting on the top of the motor, there is just a "whisker's" width there, however, part of the prop blade is blocked by the motor itself.
Here are the bench numbers for this prop on the EMAX RS2306 2750 Kv motor with the prop mounted "upside down". Tested with a Turnigy Plush 60A ESC with timing set to low and a Zippy Flightmax 2200 3S 40C battery. Further details on all the bench testing that follows can also be found on my motor testing spreadsheet.
50% throttle - 15.5A/185.3W producing 274 gr/9.7 oz of thrust;
100% throttle - 36.2A/429.3W producing 448 gr/15.8 oz of thrust.
So these results are very poor and inefficient, almost 2A required for every oz of thrust produced at full throttle. Compared to the 6x4 APC gas prop numbers of 32.4A/371.2W producing 812 gr/28.6 oz of thrust, this is a pretty sad performance😏
So while I had everything set up, I decided to give it a test on the Multistar Viking 2208 2600 Kv motor . I know based on EMAX's data this prop isn't designed for this motor, but I suppose a prop is a prop at the end of the day😉 The top of the Viking motor slopes away quite a bit from the shaft and after adding a spacer ring again, I ended up with about 4mm between the prop blade and the bell of the motor.
So here are the numbers with this motor and prop, again, same test parameters as above.
50% throttle - 14.7A/176.8W producing 304 gr/10.7 oz of thrust;
100% throttle - 30.3A/348.9W producing 526 gr/18.6 oz of thrust.
So the numbers were a bit better considering this is a lower Kv motor, I suspect the prop having some more room to "breathe" might have helped, but still pretty bad compared to the 6x4 APC gas prop numbers (29.5A/359.5W producing 836 gr/29.5 oz of thrust at full throttle).
So I gave it one more chance on the GearBest 2212/5T 2700 Kv motor, hoping that the extra size/torque and high Kv might produce a "miracle" 😇 Alas, even with increased "prop clearance", twas not to be😊.
Same test parameters as the first two, here are the numbers
50% throttle - 14.2A/171.8W producing 378 gr/13.3 oz of thrust;
100% throttle - 31A/354.7W producing 630 gr/22. oz of thrust.
6x4 APC numbers for this motor on 3S at full throttle are 32.1A/370.6W producing 1004 gr/35.4 oz of thrust.
So it is certainly not the prop's fault, I was trying to use it in a role it was never designed for. It is designed to be used right side up and most quad racing guys are using 4S or higher with the EMAX RS2306 2750 Kv motor. Perhaps with a 4S battery I'm sure it would produce more thrust, but it has a long way to go to make up ground on the 6x4 APC gas prop for the role I need it to play in my park jets.
My challenge to myself when I started this quad racing motor test craze was to find a motor and prop combo that would give me the performance I see in my park jets on 3S, so unfortunately this prop doesn't fit the bill. I do have some other 5" 3 blade quad racing props on the way to try, one never knows until one tries😉
This motor performed really well today, as good or better than the bench test numbers I reported in my initial impressions post. It certainly performed better than the RC Timer 2306 2650 Kv motor in my last video and is probably the highest torque (or at least feels like it has the highest torque) of the quad racing motors I have tested thus far. Perhaps the high Kv also helps it feel like it has a little extra torque, but it "muscled" it's way through every challenge I presented it with😊 Certainly not to make the RC Timer 2306 sound like a bad motor, it is not, but this EMAX motor certainly performed better than I expected even though it only has 100 Kv more and the stator is the same size.
As mentioned in the video, it has about the best "hole shot" of acceleration when I hammer the throttle. The one motor that would be the closest in this aspect that I have tested thus far is the BeeRotor Z2207 2780Kv motor from RC Timer.
As I mentioned in the video, where I noticed the biggest difference over all the other quad motors I have tested thus far is mid range speed and efficiency. At 60% throttle, it felt faster than any of the other setups, to the point I reduced my throws in the roll axis (both elevon and aileron) by about 10% so I could stay smooth on the sticks and "keep up" with the plane. I've flown with other motors that have about 17 oz of thrust at 50% throttle, but this one just seemed to really maintain it's energy in the range where I spend most of my time when flying. This motor is putting out 17.6 oz of thrust at 50% throttle and the plane weighs about 19.8 oz of thrust, so that is 0.9:1 thrust to weight ratio, just at mid throttle and I feel like I am getting all that thrust in that throttle range😎
In high speed runs and vertical climb outs, it maintained it's speed and energy really well, showing plenty of torque going straight up, it just kept going straight up with no lag, sag or complaints from the motor.
As I mentioned in my flight video, I have now ordered some Turnigy AE 45A ESCs from Hobby King to try with this and other high Kv quad racing motors.
Watching this video from rcplanepirate, he is getting over 1200 gr of thrust with the same prop on 3S. Granted his thrust test setup and battery are different than mine, but that should not account for 400 gr difference in thrust I wouldn't imagine, so I can only think it is the ESC he is using which is a Turnigy AE 65A, that is helping with that much increase in performance. If you fast forward to about 7:50 in the video, you can watch RCPP's test of this motor with a 6x4 APC gas prop on 3S.
So all things being equal since I have field tested all my quad racing motors on the Turnigy Plush ESCs on low timing in either 30A or 40A size, this motor is the best thus far by a slight edge over the BeeRotor Z2207 2780 Kv from RC Timer. This motor has a bit better mid range speed and efficiency when "yankin' and bankin'" around than the Z2207, "hole shot" acceleration and top speed are about the same which makes sense as their bench test numbers are almost identical.
I'm excited to keep thrashing this one about, it ran strong all day, no problems whatsoever, and being as light as it is, even 3 gr lighter than the Z2207 motor, EMAX has seems to have really done their homework on getting every bit of power out of each gram of motor weight. And considering it is rated at 58A according to the specs on the Hobby King link, there is a lot of potential there😃
If you want to see all the bench test numbers for all the quad racing motors I have received thus far, please go to this motor test spreadsheet, the quad racing motors have their own tab along the bottom so you can compare them easily.
Christmas came a bit early for me yesterday with the delivery of a couple of Hobby King orders I had been waiting for😂
Three motors and a couple of 6x3 TGS props I will be testing in the future in a 6x3 prop "shoot off"😎
In this post as it says in the title, I will be discussing my initial impressions of the EMAX RS2306 2750 Kv motor. I paid $21.99 USD for mine at the time of purchase, but shipping was free. It comes very well packaged in a hard plastic box (which I will probably recycle for putting spare parts in for my flight box😊 The grey stuff is a dense foam to protect the motor and other goodies. Also some cool stickers that will find their way onto my flight boxes😎
Goodies out of the box. Not that it is too critical for my use in a park jet, but it only came with one prop nut, most quad racing motors I have purchased come with two.
Close up of the "goody bags", sets of bolts for adapting to 3mm or 4mm thick carbon when mounted on a quad copter frame and a spare bolt and washer that holds the bell to the stator.
I grabbed this picture from the Hobby King website which is linked above showing that to remove the bell, you just need a small Allen key rather than messing around with a C clip or other type fastener, a very cool feature I think.
Once the prop, prop nut, X mount is installed, it is a pretty light little motor at 47 gr/1.7 oz. In my excitement I forgot to take a picture of it by itself before putting it in a plane, but here it is sitting beside the RC Timer 2306 2650 Kv motor I recently tested. You can find my articles on my initial impressions, bench testing and field testing of the RC Timer motor on this blog.
The RC Timer motor weighs 52 gr/1.8 oz in the same state with everything ready to fly. The wires are longer on the RC Timer motor, but EMAX has really focused on keep the weight of the motor very low, the stators on these motors are the same size and the EMAX has only 100 more Kv, so they are close that way also.
Here are the numbers from my initial bench testing using the 6x4 APC gas prop, Turnigy Plush 60A ESC with timing set to low and Zippy Flightmax 2200 36 40C battery.
50% throttle - 16.6A/205.9W producing 498 gr/17.6 oz of thrust;
100% throttle - 32.4A/371.2W producing 812 gr/28.6 oz of thrust.
You can find more details as well as the initial bench numbers of the other two motors in the first picture on this spreadsheet, please scroll along the bottom til you find the tab labelled "quad racing motors" to get the info.
I was actually a bit surprised at the low thrust numbers, after watching rcplanepirate's video (test starts at 7:50 in his video) on testing this motor on 3S with this prop, I expected the numbers to be much higher. RCPP is using a much different ESC (the Turnigy AE 65A) than I am, so perhaps I need to do a bit more research and testing to get the right ESC to optimize the performance of these quad racing motors. They sell one in 45A that I think I will order and give a try if the ESC can optimize the performance that much more, worth giving it a go😊
However, my "spidey senses" tell me that it will perform very well at the field even with my current setup. When I spin the motor by hand, it is very smooth, but I can tell it has very strong magnets, much stronger than the RC Timer 2306 motor for example, so I think once at the field it should move my plane along quite smartly😎
