Time to see what all the fuss is about with a 6s low kV rig so I can make my own conclusions. This is the first part in a multi-part blog where I will choose the parts with reasoning plus alternatives I considered and why I landed on what I did. I will follow this up with a build and betaflight settings guide, maiden flight and the finally, long term findings.
There are a lot of musings as to the theoretical reasons that 6s may be different to 4s but given this is a very empirical hobby I thought I might see for myself. Below are the parts I have chosen and why. For the record my goal is to make a high-powered and durable build that is easy to setup and service. Light weight is a bonus but comes behind durability and power. For servicability you will see I have chosen mostly recognised brands to ensure they are supported and spares are available in the long term. I have no desire for HD footage but clean DVR is a bonus.
FC and ESC
I have chosen to go with the HGLRC Titan F4 60A stack here. Click on the link for specs but I have chosen this stack combo because it is guaranteed to do 6s whereas many others are not officially rated above 4s (i.e. not warrantied). Brave testers have however found that others such as the EMAX magnum full size stack and the airbot Ori32 which I have a soft spot for. Another good option is the New Emax Mini f4 stack but until there have been more reviews I like the idea of a larger 4in1 ESC like on the HGLRC titan for better heat dissapation. I did not consider separate components here as there does not yet seem to be a common wiring standard from FC to ESC. A quick note that the titan is rated to 60A per channel on 4s, 50A on 5s and 40A on 6s. I have no issue with this because for a given power, current draw will decrease proportinately with voltage increase i.e. higher voltage, less current for same power. I also like that BLHeli_32 is aready pre-wired into the flight controller via the included wiring loom :) I would recommend buying directly from HGLRC for the best customer support.
To give this a devent go and make it a real powerhouse I've gone with the HobbyCool 2207 1700kV. While this looks like I've gone against known brands they are actually a Brother Hobby R3 2207 OEM available in 1700kV and 2300kV. I've chosen 1700kV since these are the equivalant of 2350kV on 4s. Although this seems like a low-mid kV option I tend to prefer lower kV motors and this seems to be where many motor manufacturers are targeting for 5 inch race quads running 6s. My other key motor consideration here was the Hyperlite 2207 1722kV but this is more expensive and often out of stock. I also considered the Emax LS2207 but have heard questions about durability which I'm not willing to compromise here. A quick note that I've chosen 2207 as a stator size as I perfer the 22mm width and 7mm height is the largest practical height for now. 2306 is a popular size too but has less stator volume than a 2207. These can be bought directly from HobbyCool.com and buying a set of 4 will get you free shipping.
I considered getting the HGLRC GTX585 to go with this (25mW-600mW with MMCX and tramp control) but decided on the HGLRC DVR-VTX AIO instead since it has similar funtionality from a VTX standpoint BUT it has an onboard DVR too - this first time these two components have have been offered in one tidy unit. This unit will can run at 25-100-200-500mW, has MMCX and will accept up to 6s (26v) directly meaning if it is wired to VBAT will put less load on the FCBEC which is important because the DVR will have a reasonable power demand alongside the VTX itself. Like the Titan stack, I would recommend purchasing directly from HGLRC
Since I went with the onboard DVR I wanted to get the best image currently available. It's not cheap but I decided to go with the Runcam Micro Eagle. It simply has the largest image sensor currently available in a micro cam = more information to generate an image from. My favourite is usually a foxeer micro arrow pro as a good budget option but really wanted to give this a chance to see if the hype is justified.
This is probably the hardest decision of all. I wanted it to be somewhat lightweight but durable. The first frame that came to mind was the Hyperlite Floss2 and Mode2 Ghost. Both of these frames are super-functional for racing (strong and lightweight) but I already have both in other builds AND I feel they look pedestrian. This was my chance to try something different so ultimately settled on the HGLRC Batman220. My line of thought is that this is a newly released BNF model that looks like it will be very popular and hence well supported with replacement parts and in the open source community with 3d prints etc. The frame has separate arms that are 5mm thick and weights a hair under 80g with all hardware. It has a look that is unique that doesn't look to be a clone and has a nice sturdy FPV cam mount similar to the hawk 5 which I prefer over the TPU mounts that sit on standoffs like the floss and ghost series. It has only 3 motor screw holes which should make the arms stronger at the ends - I have broken Floss 2 arms here before although they were only 4mm. There are 3 screws holding each arm to a sandwich plate so it should have minimal play. Press nuts for quick replacement is a nice touch. This is also one of the cheaper branded frames I've come across at only $36.
This may sound like an odd choice but I've had tremendous success with the RealAcc UXII MMCX. Yes, this series started out as a clone of the TrueRC/Lumineer AXII however so far as I know the direct MMCX connection as pictured is a unique innovation by RealAcc. I'm a little conflicted on this though because RealAcc tends to be the worst offender for cloning. I suppose this way I'm encouraging their innovation rather than cloning. This antenna is small and compact and sacrifices some transimission power for robustness. Being so close to the body of the quad means it is well protected but it can mean the carbon fibre frame can block transmission in some orientations. In fairness though this is a racing rig and racing so their is minimal distance between the vtx antenna and your video receiver. If range is an issue I'd recommend the Emax Pagoda which is a no-nonsense CP antenna that recognises the designer and costs no more than it needs to be with a decent level of quality control. The RealAcc AXII MMCX is available for about $6 and the Emax Pagodas are about $14 per pair.
I'm going to leave props out of here on purpose because I want to see what is going to be most suitable out in the field. My best guess is something relatively agressive like the HQ 5x4.8x3 or perhaps the new 5.1x4.6x3 which sounds like a good balance. If they are not durable enough I'll try the Dalprop cyclone T5045c or T5046c. Additionally I'll need to follow up on battery because it will depend on availability as I somewhat geographically isolated and many local carriers are afraid of Lipos. More to follow, I'm hoping I can source something that will be available to most people worldwide.
Please look out for the next blog in this series (Part 2) where I'll go through the build. Will link here when available.