T-mount propellers are those that are based on a 1.5mm diameter centre shaft secured by a 2mm screw either side. They have been the only mounting option for 2-2.5 inch props but are now becoming more popular for 3" due to the weight they save over a 5mm single shaft prop mount. There are only 4 different types of t-mount 3" prop currently available so I've compared them all plus the new HQ 2 blade which is due for imminent release plus a darkhorse prop in a smaller size to make up the numbers. Please note this is a subjective comparison based on my opinion but my help as a startpoint for your decision. This is based on real world feel, light time and bitter experience with motors I've burnt out.
Emax Avan 3 inch tri-blade
This is the first modern design 3 inch prop designed for a t-mount which was released with the 3" Babyhawk R (reviewed here).
HQ 3x3x3 v1s tri-blade
HQ props have the newest 3" t-mount prop design at present. This has been chosen as the stock propeller for the Full Speed Leader 3 (initial review here and flights here)
Gemfan 3035 triblade
This is quite an old prop and can be hard to find but is still suprisingly relevant.
Gemfan 3025 bi-blade
This is the original 3" t-mount prop and so can be found for sale in weird and wonderful places
HQ 3x3x2 v1s bi-blade
Just released at the time of writing: as per the 3x3x3 above but bi-blade rather than triblade. Disclaimer: I have not tested yet and below information based on assumptions from comparing bi-blades and tri-blades in general. Will update once mine arrive and I've tested.
Dark horse to consider...
Gemfan 2540 flash triblade
Yes this is a 2.5" prop but objectively it is so good it is worth considering downsizing. You can find an earlier review I did on these here and a review on the Skystars Bolt X120 which uses these on 4s here
Please note the King Kong 2840 propeller was not included here because I found the Gemfan 2540 superior in every way. Also I have not include the Rotor X 3044 because it is difficult to source where I am based. The feedback that I have had is that it is more aggressive in pitch than any of the above props and probably only suitable for for stator sizes 13xx and up.
If you haven't yet seen the first part of my Leader 3 (SE) review, click here. In it I cover an overview of the New Leader 3 including full discussion of the components, build and software setup. A quick correction too: I mentioned originally that the flight controller (namely the gyro) will only do 8kHz loop times. This is incorrect - it will actually run up to 32kHz! Certainly the first I'm aware of on a board this size and something for me to test in future.
Before I go any further I should note that my Leader 3 is a review model and so there may be minor improvements in the final version shipped to buyers. I'm in regular contact with Full Speed RC to give them feedback on what I find to assist with these improvements. The Leader 3 is available directly from FullSpeedRC.com, Gearbest or Bangood.
Since FPV performance is common between 3s and 4s I thought I'd cover that first. In short it is outstanding. Fullspeed RC shared a lot of the development of the included TX600 vtx with me an a lot of effort went in to ensuring a clean video signal all the way up to 600mW and the results sure doesn't disappoint. The result is that the Leader 3 has the cleanest video signal I have every used. There is absolutely no impact of throttle or other electrical noise on signal and it is hard to put in words just how much more enjoyable this makes the signal. I do miss the audio that AKK VTXs allow for but most people don't rate this as being important, especially on a micro. It's noteworthy that the the transmission power will go as high as 600mW - equalled only by the AKK FX3 ultimate (review here) in this form factor. OSD control of settings via Tramp works as expected. Antenna connection is via UFL is common for micros and fit for purpose.
No propellers in FPV view
Great news for those who don not like seeing their propellers - the frame design means that even with fairly modest camera angles of around 35°and up there are no props in view. Hopefully this is clear from my videos below. This also make the drums for a Caddx Turtles HD camera install beat even louder...
I wanted to clear things up on camera angle since Nick Burns mentioned it couldn't go past about 45° in his otherwise excellent review. I can confirm that the camera connector does not foul on the flight stack and does infact smoothly go all the way up to about 90° amgle. Pictures are best here so please see below:
Performance on 3s
When the Leader 3 was shipped to me, 2 custom PID prodiles were programmed in by fullspeed, Profile 1 was designed for 3s and profile 2 for 4s. 3s was tested with profile 2. Both of these profiles can be seen in full in part 1 of the review here. For 3s testing I used Turnigy Nanotech 3s 450mah 65c batteries. They weigh less than 45g meaning all up weight was around 140g. Flight time using these batteries was typically around 2.5-3 minutes with batteries coming to a resting voltage of arounf 3.75v per cell.
Flying exclusively with the HQ 3x3x3 propellers flight felt very 'balanced' - what I mean by that is the quad didn't feel overly heavy (or light), top speed was fast enough but not ludicrously fast like the Skystars Bolt X120 on 4s (review here). It was however very predictable - I could hit gaps and avoid obstacles in a way where I felt I had complete control. It was fairly similar to the way the Emax Babyhawk R 3 inch felt (review here) but the HQ props felt more predictable and familar compared to the EMAX Avans. This makes sense - both the Leader 3 and Babyhawk R are of similar weight and with 1106 4500kV motors on 3 inch props and both have optimised PID tunes. Full Speed RC seem to have done a good job on the tune here not just for the feel during flying but also in keeping propwash to a minimum, even when I tried to put myself in dirty air in 180° turns or descending directly down.
Below is a video from an early flight (2nd pack ever) in a local carpark. Typical I had DVR issues in a flight later that day where I'd gotten more familiar with the flight characteristics :/
Performance on 4s
The battery I used for all 4s testing was the China Hobbyline Ministar 4s 650mah pack. It is an excellent battery that I even use on my 4 inch racer so is very capable although a little heavy at 87g.
First of all I'm going to talk about straight up speed and my perception. It did not feel as fast as the Skystars Bolt X120 using the same battery. This is not an objective measure, purely feel. It did feel faster than the Babyhawk R 3" using the same battery.
To dig in to this further though I do need to say that that Skystars Bolt X120 is very hard to control with this battery and I did not enjoy flying it because it felt difficult to control. It felt like it needed more open space which then kinda defeats the purpose of a micro. By comparison the Leader 3 felt in complete control using 4s and PID profile 2 as customised for 4s by Full Speed RC. As a result it felt right at home on 4s with all the control and balance I felt on 3s. I think part of this is due to tune but moreso that that larger 3 inch blade is able to better support the additional weight from the heavier pack and hasn't overloaded the propeller (disc loading theory).
All other features of flight were similar to 3s - excellent video, precise handling and minimised propwash. I was really enjoying flying this until...
When I first received this model, Full Speed RC cautioned me to use 4s using the smaller Gemfan 2540 props (review here) since motors could overheat. Since I was the only reviewer to receive mine where it is winter presently rather than summer, this was less of an issue although I did keep an eye on motor temps. For this reason I stuck with the included 3 inch props for 4s.
About 10 packs in of warm motors (40-50°C only) I fell out of the sky when attempting a short speed run (see video below). On closer inspection the left rear corner had failed that I could later confirm as a motor failure (as opposed to ESC). The motor definitely was warm only as above and not hot. The only other time I've had a motor failure was on the babyhawk r when I used PIDs with too much P and D on 4s and even then the motor did not fail mid flight, rather afterwards intsead. This motor was scorching hot.
I discussed this with Full Speed RC and found that they will be using a stronger motor on the production version - the review version like I have are a prototype. As you can see below when comparing to my burnt out motor on the Emax Babyhawk R, the Fullspeed one does not look nearly as abused - it failed at a much lower load. Interestingly shortly after this I saw Andy RC's review and found he had an identical problem - motor failed mid run using 4s with HQ 3x3x3 props. Update: The prototype motors are actually 4800-4900kV and the production version will be 4500kV.
So, what does this mean for you? Until I can confirm that Fullspeed RC have moved away from the proptotype motors I can't recommend using the HQ 3x3x3 props with 4s, even in cold weather. For now stick with Gemfan 2540 props on 4s. Of course if it ships with new motors then all bets are off. Full Speed RC is sending me a full set of new motors so I will test with these and post my results in a follow up review as soon as I am able. Update: The prototype motors are actually 4800-4900kV and the production version will be 4500kV.
The Full Speed RC Leader 3 is as an excellent flyer on 3s - great video signal and predictable handling make for an enjoyable flying experience. On 4s the Jury is out... custom pids make this fly well too but the motors' inability to cope with the included 3" props are a bit disappointing. For now a bandaid solution is to run with Genfan 2540 props on 4s but I expect that Full Speed will release with a stronger motor for launch as they did with the original Leader 120. Again, my sample is a reviewer model and this feedback is used to make changes if needed to the final launch product. Full Speed RC has proven themselves to be a reputable company with well researched (and tested) quadcopters and I expect them to follow through on this model too.
The Leader 3 (SE) is a follow up to the hugely successful Leader 120 which I have reviewed and documented modification extensively, most recently with a summary here. Both are available from Fullspeedrc.com This has been a highly anticipated release not least of which because there has been no releases from Full Speed since last years' Beebee 66 light. The good news is that a big chunk of that wait has been spent working on the Leader 3. FYI two of the main guys are pilots from Full Speed RC are pilots and do a lot of work testing before release which is a welcome change in this hobby compared to many models that come out half-baked.
Firstly the Leader is available in 2 variants. The standard model (Leader 3) can be seen below and weighs 87g with regualar standoffs. The Leader 3 SE is exclusive to Fullspeedrc.com and comes with a 3d printed canopy instead of the standoffs. It is 6g heavier but offers several benefits that I'll cover a little later on.
A run through the components
First the frame. Like the Leader 120 the base plate of the frame is 3mm thick although it has been stretched to 130mm motor to motor diagonally rather than 120mm This means it is capable of accepting a true 3" propeller rather than 2.8" maximum on the Leader 120. The frame is most definitely still a 'deadcat' shape meaning the two motors are further apart (107mm) than the 2 rear motors (98mm). Additionally it is a 'squashed-x' compared to a 'stretched-x' meaning the front and rear motors on the same side are closer together. This means it should be more stable in the roll vs. pitch axis but modern flight software somewhat negates this. Compared to the leader 120, sideplates have increased from 2mm to 3mm thick which should aid durability. More imporatantly a 19mm gap rather than 17-18mm means the leader 3/SE now natively fits a 19mm micro cam. It's worth nothing that the baseplate is only 1 piece so you cannot replace single arms. Personally I think replaceable arms are unnecessary on any quad size less than 4" since there is much less leverage for breaking on a smaller quad. The frame can be purchased separately here.
The canopy (Leader 3SE only). When I first saw the canopy I wasn't keen because it adds 8g weight however I think the functionality may just offset that - jury is out until I fly it some more. The 3d TPU print is of very high quality available in black,white, red, purple, blue or yellow and performs the following functions:
The motors are 1106 4500kv which is the same specs as those found on the Emax Babyhawk R 3 inch and the Skystars X120. They are not open bottom and have mounting holes for regular t-mount props and the emax 2.3" avan props. Most importantly they are rated for up to 4s.
Like the original Leader 120, build quailty is excellent. Solder is clean, wires are cut to length. Not much more to say here, it is well beyond my ability! With the quad assembled there is plenty of room behind the camera to adjust tilt (45° and beyond are capable) and the receiver is mounted in this void. with plenty of room left yet. This is speculation but I'd like to address anyway since it seems like a common thread: my best guess is the caddx turtles HD FPV/DVR (not yet released at time of writing) will fit but not without a little modification. My reasoning is that there seems to be 2-3mm 'spare' room between each stack layer. If these standoffs are trimmed by this amount you will be able to save 6-9mm in height which should be enought to fit the turtles board. It will require some fine wire management and a steady hand to trim the standoff but I do think it may be physically possible - a project for another day. That being said, the double stack of the runcam split micro definitely will not fit.
Plenty to talk about here although most can be foundin commentary of the Betaflight screens below. If you don't choose to read these however:
Final thoughts pre-flight
As you can see from above this looks to be a very well thought out quad and not something slapped together from a spare parts bin. The Babyhawk R and Skystars bolt X120 have both shown that 1106 4500kV motors perform well on 4s in 2.5" and 3" so I am excited to see what the Leader 3SE will add here with all the work that has gone into development from a hardware and software perspective. On paper this looks to have the edge on both of those models in terms of weight, VTX capability and ESC current overhead however the real test will come in flight - stay tuned for part 2 of this review where I will cover flight in full - I already have 3s and 4s batteries charged for tomorrow :)
The Fullspeed RC Leader 3/SE can be bought directly from Fullspeedrc.com and is also available at other retailers however buying from the source is your best chance to get your hands on one quickly.
The Emax Baby Hawk R is a micro brushless quadcopter that was launched by Emax in early 2018 as a follow up to the highly successful Emax Babyhawk (not r). It was launched as a 2 inch but 2.5 inch aftermarket arms quickly became available in the aftermarket and hugely improved the power to weight ratio, disc loading and efficiency. Emax themselves have now taken this one step further with the Babyhawk R 136mm (3 inch). Compared to the 2 inch version is has the longer arms with the new Avanflow 3 inch 3-blade propellers and a reduction in motor KV from 6000kv down to 4500kv although motor size is still the same 1106. Weight of the 3 inch is 86g compared to 82g. I will review the Babykawk R 136mm (3 inch) here.
Specs and discussion
On paper none of these components are especially exciting or on the hype-train. A big HOWEVER though - all are very tried and true, solid and well balanced. This means reliability and reduced cost. The each have a job to do and do it without fuss or flair. It's fair to say though that when you bring them together they are greater than the sum of parts.
Quick rambling thoughts how 3 inch quad weights
I think of 3 inch quads in 2 ways - a shrunk down 5" based on large motors and 4s batteries or an embiggened micro based on 11XX series motors and 3s. This clearly fits in the camp of "embiggened micro" since it is based around 1106 motors however it is farily unique in that the ESC, motors as well tough frame and cowling are well and truly engineered for 4s - best of both worlds as it were. By constrast my lightweight FlexRC komori (build blog is here) can take 4s but the frame would not hold up to carrying the extra weight of a 4s. Conversely something like the Furibee X140 (review blog here) is pretty gutless on a 3s where it can't overcome the 120g+ weight of the quad.
I haven't delved into all the betaflight screens this time because for the most part this is down to preference and your gear. What I can say though is that although not installed from the factory, EMAX have provided some VERY good PIDS for both 3s and 4s. Here is the link to their page or for convinience please see below:
Fly the damned thing
At the time of writing I've only run this on 2s and 3s. 2s was using a 46g 950mah turnigy nanotech battery and was very uninspiring but hey, at least it can be done! 3s was much better than I thought it would be. I used the Turnigy Nanotech 3s 460mah battery (about 42g) and got 2.5 - 3 minutes flight depending on how hard i pushed, coming down at about 3.75v per cell at rest.
The first thing I have to say about the flight is that all of these solid if unspectacular components do come together so nicely - they are all well suited which not only make for an enjoyable and reliable fllight experience but means the cost does not blow out. In addition the protection offered by the 3mm carbon-armed and cowled frame means that even after tumbles there is a good chance you can just rearm and get flying again - it is tough! The other benefit of the cowl is that it looks cool, different from the top plate/bottom plate or side cage frames that are out there.
Punch out power is ok on 3s but will hold my judgement till I get some 4s packs. understandably the light 3s packs make for great agility which is why I had a lot of fun with proximity around the small trees in the park that I have close to work.
For FPV camera performance is good - as to be expected from the foxeer arrow micro CCD. VTX is clear in the right conditions and is better than most other micros however I do undersand this can be improved significantly with an AXII ufl antenna (or the cheaper UXII). Channel and power level is easy to change via the small button but as suggested above there is no smart audio or tramp protocol to do this over betaflight OSD.
Obviously I haven't tried on 4s yet (I am just choosing a 500-700mah 4s to order), but based on the performance of 3s I think this quad is a real winner.
Emax have done a fantastic job on not getting carried away on needlessly overspeccing the quad in areas you cannot really taking advantage of. In doing so they have a solid, robust and well priced offering that I can see becoming very popular like the babyhawk before it albeit with less shortcomings. Better still the support that emax appear to be offering beyond regular customer service such as offering tuned PIDs means that community support will mean there are always going to be clever fixes and modifications that will be available, making obsolesence for this model is less likely. Make no mistake obsolesence is a real issue with quads because once the community moves away from a model there is less support in total available.
Although experienced builders and customisers will still likely want to build their own, It is very easy to recommend this as a first 'racing' micro quad becuase of it's inherent features and support. As a micro quad builder myself it's hard for me to say but this is actually more enjoyable to fly than most of my custom builds because it all comes together so nicely. For that reason it is easy to recommend this to the more experienced set that just want to fly and not fiddle with the micro electronics etc - for example if you have come from 5 inch racing or freestyle quads.
The Emax BabyHawk R is currently available from Gearbest with or without receiver. The model without receiver is $166. If I get access to any specials I'll post on my coupons ans discounts page.