Gemfan have recently released the 2540 Flash propeller to add to their growing library of micro propellers. This time rather than sticking with their 'Hulkie' naming on the 1940 and 2040 propellers, they have gone with 'flash' from their popular 5" 5152 prop.
The design is stylistically similar to the 5152 in that it is a swooping 3 bladed propeller with a pronounced wingtip. Colours currently available as below. I like the yellow as they are easy to find!
The material feels very much the same as the gemfan 2040 Hulkies which I reviewed here but the design is much more refined and so will not make any further comparisons as design will impact performance and durability more than material.
For testing I used my Leader 120. This is a popular model and I have put 80 odd packs through this one making it a good test mule. Also, I have experimented with other props like the Gemfan 3025 alongside the stock King kong 2840 for more than one point of reference.
Since this frame will fit a 2.8 inch 2840 prop there is plenty of room on a 2.5 inch 2540 without losing too much blade area. No issue installing so will move on to flight performance.
Performance on 2s
The first thing I noticed about these props is that they were very quiet. I flew in a reserve where there were several people enjoying the sun and very few people even noticed the quad flying about. The noise made was even less than the 2840s which are already very quiet. On 2s the performance was almost on par with the 2840s. I was able to hover at around 25% throttle with a 47g 950mah 2s battery and had flat out speed close to the 2840s. Cornering (grip) felt about 90% as good as the 2840s which is the grippiest quad/prop I have - even more than my 5" racing floss 2. Balance was excellent with no increase in jello at high throttle over the 2840s which have always been well balanced for me.
Battery life was definitely superior to the 2840 props. As you'll see from my pics below I got around 6 minutes from the 950mah battery with fairly heavy throttle flights as I was in a large reserve. This is about a minute more the the king kong 2840s with similar flying and comparable times to the Gemfan 3025 (although the 3025s were slower on 2s). It was an enjoyable 6 minutes too - the quad felt tight with these on.
Performance on 3s
For 3s testing I used my Turnigy Nantoech 3s 450mah 65C batteries that weigh approximately 45g.
The performance gap between the stock 2840 and new 2540 propellers were even less pronounced than on 2s. If there was a difference in performance compared to the 2840s in top speed or cornering grip I could not tell. The advantages did remain though - 2540 propellers were again more quiet and I had a similar increase in battery life: from roughly 3 minutes of hard flying to roughly 3.5 minutes+ hard flying (see below). Lastly at higher RPM I actually had less jello than any prop I have used on this quad before. This suggests they have excellent balance.
In short I got all of the benefits I enjoyed on 2s with none of the downsides.
Oddly enough I haven't had a crash worth speaking of yet. I'll update here once I've had a view and can give more of an opnion on this.
Simply put these are now my favourite prop on both 2s and 3s for the Leader 120. I can only guess that the more modern design helps get the efficiency up over the 2840 on 2s with very nearly the same top speed and grip through corners. On 3s the gap was even less and I'd struggle to tell the difference between these and the 2840s. The only real change was that there was less noise and more flight time.
In conclusion these will be my go-to prop from now on my leader 120 on 2s or 3s. The slight downside of marginally less top speed and cornering grip is easily outweighed by the reduced noise and improved battery life. Give them a try for yourself, they are inexpensive.
This is part 2 of my review of the Leader 120 by Full Speed from Gearbest. For part 1 click here. As at September 2017 try code HarvestRCnew7 to get this for only $US93.99!
None of the dreaded "brown outs" here
Straight up I have had none of the reported issues of brownouts as many of the youtube reviewers found on the first version of the Leader 120. In saying that my review modelis version 2 which I has the fullspeed branded black motors. The default idle speed of which there was a lot of chatter about was set at 10% from the factory in Betaflight 3.1.7. This is very high and reducing it to my regular 3.5% caused no issues. So on to the more interesting stuff!
This is a great little flier, As I expected from hearing the motors run in betaflight they are very quiet and coupled with the well-balanced KK 2840 props it lets off very little noise in flight. Coupled with the size, this makes it much more socially acceptable to be flying in areas that aren't completed isolated. The rates are not stock either and I actually really liked them, even compared to my stock betaflight 3.2.0 settings when I flew my 5" quad immediately afterwards. There are an awful lot of micros that have poor or no tuning from the factory so was escpecially pleased when the tuning here required practically nothing for those either lacking the know-how or too lazy to do. Power is excellent on 2s and comparable to many 2" quads on the 3s - the bigger props and relatively light weight really make these motors come alive. Handling was predicatable and I felt I had good control even in heavy gusts.
The stock battery can be described as adequate. I can see the voltage alarms were set low at 3.0 warning, 2.9 critical to allow for the sag but it keeps you in the air with moderate flying for up to 4 minutes. Considering I was able to flow without esc desync, losing vtx signal or getting failsafe, this probably makes it better than 90% of included batteries out there (not kidding).
I'll have a follow up tips and tricks article soon where I look at some of the other internationally available battery options including 3s.
FPV - Camera and VTX
Ahh a chink in the armour. Hitting a sharp price point eventually means compromise and I think I've found it. Typical of All In One (AIO) cameras this handled low light on a dull day poorly even with the focus correct. Kind of makes branches jump out at you when flying under trees - that's my excuse anyway. Secondly although the VTX does well enough for 25mW, it still only does 25mW. That means that I started seeing breakup at 100-150M away or as soon as I was on the wrong side of even small trees. The good news is you can pop this on your RC car or tiny whoop (I STRONGLY recommed the Eachine E011) and upgrade this one. There is more than enough lift for the extra weight of a micro CCD camera like the Foxeer arrow micro or Runcam swift micro and a Vtx like the new one from fullspeed that is 25mW/200mW switchable to mount on the back. I'll be making such a change in the near future and reporting back in a new article in the tips and tricks section.
This model is an amazing combination of well-matched parts with good assembly and a custom tune making it compelling on paper. I'm pleased to say that this transfers into flight characteristics and power making it an option you should definitely be considering if looking at a micro in 2017. I personally think this frame size that allows for a 2.8" prop rather than 2" is much better matched to this motor size and not nearly so sensitive to weight meaning for a more robust and enjoyable flying experience. My only real gripe is the video quality where camera light handling and vtx power lets it down. It is hard to argue at this price point though and in a future article I'll be doing a budget mod to address this.
Most interestingly, I built a model from parts that was very similar to this before this model was announced. Cutting to the chase the PNP version from Gearbest was more quiet and felt more solid in the air (perhaps due to the tune/rates) than my own build. Power was similar: although noisier I think the DYS motors had an edge although for the small difference I prefered the ones in this PNP model. I preferred the adjustible power vtx on the model I built to bump up power but this is really starting to split hairs. This does have me second guessing my build vs buy strategy but I think this is testament to the well thought out component list Full Speed have chosen.
Buy the Leader 120 from Gearbest
Firstly, thank you to Gearbest for supplying this model in exchange for a full review including my observations and recommendations from having built a very similar quad from parts. I'll review here and then run a series of tip, tricks, mods depending on how it flies stock. You can find the PNP version (no receiver) here. As at September 2017 try code HarvestRCnew7
to get this for only $US93.99!
I'm going to skip the unboxing, I don't have anything to add other than the picture of all the parts included below, so straight to the good stuff.
The parts included and build quality have improved...
First off the motors are no longer and unbranded red 1104 7500kv. They are now branded SZ speed and full speed but are still rated the same. From what I can see the shaft length extending through the bell is shorter. Great idea - the only job this does is to centre the prop which the screws hold on. Less stress when trying to put tight props on (looking at you Gemfan 2035) and you don't have a 1.5mm drill bit. Below is a comparison to my DYS 1104 7500kV. You can see my review on these here
The comparisons to these motors don't stop there. Both are similar external size, and the magnets are simlarly strong - very notchy compared to the racerstar motors. From there the leader 120 motors are better. Wires are multicore, slightly thicker and much more flexible and easy to manager. On spin up in betaflight they are so quiet and smooth! Not noisy like the DYS even when they were new. In fairness the DYS are powferful so if the stock leader 120 motors get anywhere near this I'll be happy, especially given the improvements.
This flight controller and ESC is ubiquitous and first appeared on the ARFUN90. I've reviewed one in full here - in short reliable and well featured. What impressed me here was the quality of soldering and the cable managent, just so clean - see below. I wasn't going to compare my efforts but I'd already soldered in the receiver and the macro image makes me feel inadequate! From what I can see of the earlier reviews, this looks to have improved substantially.
Betaflight setup and the Flip of Death
This model shipped with the full release at the time of writing - 3.1.7 (3.2.0 still in release candidate). Interestingly along with the physical changes the software settings have been changed to address some of the brownout/flip of death issues the early reviews had. Most notable digital idle is set at 10%. Since I'll maiden this with stock settings I'll go with that and see if moving back to my standard of 3.5% is still viable. 10% is not ideal for me as you will never be able to fully chop throttle for flips and whatnot. Cool to see that they have addressed it and looking forward to seeing if this issue may have gone altogether.
I'll post some pics of the key betaflight screens for prosperity below (flip through them) but I intend to move to 3.2.0 as soon as I have completed initial flights and can confirm everything is functioning as expected.
I'm something of a lightweight jukie when it comes to miniquads, benefits include longer flights, better agility, greater crash resistance through lower intertia. See the gallery below for the various weight measures but in short 64g dry, 94g AUW ready to fly with the stock 2s 500mah battery. This include an ibus FS82 1g receiver which was not present when I too the photos.
This is a very respectable weight for a micro that swings 2.8" props as these props generate a significant amount of lift in combination with a motor of this rating.
All this and it includes my favourite beeper/led combo (reviewed here) - a beeper is a must for micro quads as you can loose them even in short grass! I can anyway.
Size comparison to other micros
This is not a big model by any stretch. The beauty of these micros - and to be clear this is still a micro - is you can fly in small areas (not indoors!) with less danger and concern to the public. They are also quick to get in the air and consumables like batteries and props are cheaper too. This model measures 120mm diagonally motor to motor and offers most of the experience of a 5" FPV quad. Picture below compare to an E011 typical tiny whoop and an 80mm EYAS x2 with 2" props
Just a guy reviewing RC Quadcopter stuff