Your first 7-inch FPV drone

I love 7-inch FPV drones and during the last year, they were my most used FPV gear. For freestyle, cinematic, cruising and long-range. I currently own 3 7-inch FPV drones and 4th one in the assembly process.
I think of myself as a 7-inch expert. I've wasted enough money and equipment to know what works and what does not work well with 7-inch propellers.

TBS Source One 7-inch FPV drone

If you are thinking about building your own 7-inch FPV drone, here are some tips that might save you a lot of time and a lot of money on wrongly chosen equipment.

The Frame

Of course, the frame is the most important part of a build. No matter if you will be building a freestyle or long-range rig, there is one thing that you have to know: Horizontally scaling 5-inch frame by making arms longer is a no-go. Longer arms require more stiffness and they also have to be thicker! The sweet spot is 6mm thick good quality carbon fiber. 5mm thick might work too but forget about 4mm or thinner arms. They will be too flexible and the whole quad will be in a state of a constant wobble!

Alfa Monster 7-inch FPV Frame

If you are looking for 7-inch frame recommendations, here are my choices: Team BlackSheep Source One with 7-inch arms, Alfa Monster and AlfaRC Fighter.

Propellers

Kind of obvious, right? The choice of good 7-inch propellers is not that big as one might imagine. Sure, you can buy some "inventions from 4 years ago for cheap" but believe me, they are not worth it. There are 3 types of modern 7-inch propellers that I find worth looking at in late 2019:

  • DAL T7056C – good for freestyle and thanks to aggressive pitch they are very dynamic. Can be used no longer flight, but this is not where they really shine.
  • HQProp Durable 7x4x3 V1S – a more aggressive version of 7×3.5×3 that in my opinion works much better than original. Slightly more pitch only helps during steady flight. They are rather for cruising than for freestyle.
  • GemFan FLASH 7042 – kind of good propeller, but don't get me wrong, you should try 7042 only if DAL or HQProp are too heavy for your motors. So if you have 2207 or 2306 you might try FLASH. If you have bigger motors, just go with DAL or HQProp.

Motors

Brotherhobby Avenger V2 2507

Probably the most often made mistake by the "7-inch virgins" are too small motors. Beginners think that putting the same motors that work great with 5-inch propellers on a 7-inch frame is a good idea. OK, maybe sometimes they lower the KV. This will not work. I know. I tried that by myself and only wasted some money and a lot of time and nerves.

What you need are big motors. In a size of 2506-2507. 2208 might work as well and 2508 is rather the max size that makes sense.

On the KV size, the rule of thumb is that on 4S you should aim at 1500-1500KV and on 6S at 1200KV. Those values give a nice compromise between efficiency and raw power. Of course, this is only a rule of thumb and when needed you might choose higher KV. For example, my 7-inch freestyle drone uses 1700KV on 4S motors.

My recommendation is rather simple: for now, there is only one motor that comes is wide enough KV range and it's called BrotherHobby Avenger v2 2507.

Everything else

For the rest of the equipment, you can choose whatever you want. Any equipment will work and you do not have to match it to the propeller size. My choices are:

First glance at Armattan Rooster FPV quadcopter drone frame

After flying chinesium (XMR250, Reptile X4R 220, Martian II) and frames from DemonRC I've decided to switch to completely different brand. My choice is Armattan Rooster, the newest freestyle frame from Armattan.

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Armattan Rooster FPV quadcopter drone frame

Rooster arrived few days ago, and this is what I can say about it before putting all the stuff into it:

  • sunken nuts you have to install by yourself are a very idea. It's hard to do without tools and skills. It would be much much better is they were preinstalled. Armattan, please, fix it!
  • additional pair of standoffs between plates would not hurt
  • it is tight inside and I will have to be creative to fit X4R and TBS Unify Pro in the back of the frame
  • frame itself looks good tho. I might even say it is pretty

3D printed racing drone, part 3

It is done. It is alive. My 3D printed FPV racing drone works. A few weeks ago I finally flight tested my design and it works! Even better than expected, since I survived the experience without a scratch. OK, I did not crash it yet, but give me some time for that too….

3d printed fpv racing drone

And I have a cool name for it: Isando which means hammer in Zulu. Kind of fits, right?

Ah, STL files are available on Thingiverse of course.

3D printed racing drone, part 2

My 3D printed racing drone is done. More or less. I was able to finish it a few weeks ago and even perform a maiden flight. It survived the experience, but I also discovered few problems I will have to solve before officially calling this project a success.

3D Printed Racing FPV Drone

3D Printed Racing FPV Drone

First of all, the decision about hard mounting a flight controller and not installing a capacitor on mains was a bad one. Not only motors are "twitching" from time to time, a video is very noisy. I hope big low ESR capacitor will solve that, since there is no way for soft mounting for this frame.

3D Printed Racing FPV Drone

Besides that, it worked just fine. I will try to prepare a video from the maiden flight in a few day, for now only a few pictures and final specification:

  • Frame: PLA 3D Printed, 220mm motor-to-motor diagonal
  • Motors: EMAX RS2205S 2300KV
  • ESC: Racestar RS30A BLHeli_S
  • Flight controller: FrSky XSRF3O running Betaflight 3.2
  • VTX: TS5823 200mW
  • Camera: RunCam Swift
  • Total weight, no battery: 380g

Total build is, of course, heavy, but not that heavy as I feared. I was expecting something way above 400g. The frame is also quite stiff. I wonder how much beating it will be able to take….

3D Printed Racing FPV Drone

EXUAV Y120S drone racing frame: go home designer, you are drunk

Chinesium is amazing. Well, to be precise, not only chinesium manufacturers will do anything just to stand off a little. Just like this little (120mm) quadcopter frame called EXUAV Y120S. Why do I even bother to write about it? Simple: I love crazy designs. Just look at those pictures below:

EXUAV Y120S 120mm Mini racing frame

No, it’s not a tricopter. It is a quadcopter. But where is the 4th arm and where 4th motor goes? Below rear motor! It’s a Y with 2 motors on arms in the front and 2 motors on one arm in the back. Rear motors are counter-rotating! Read More

3D printed racing drone, part 1

I've been pretty busy last 2 weeks. Among other things, I've started to design 3D printed racing drone frame. I'm fully aware there are plenty designs available on Thingiverse, but almost all of them forgets that plastic filament is not carbon fiber laminate and what works well with carbon, will fail with filament. So, I came up with this:

3D Printed Racing Drone

3D Printed Racing Drone

  • suitable to 220x and 230x motors with 19x16mm hole spacing
  • fits PCB and 36x36mm flight controller (30.5mm hole spacing)
  • size: 220mm motor to motor (diagonal)
  • fits "standard size" FPV camera

It is heavy for sure. It has thick arms and a lot of M3 nuts and bolts connecting all the parts together. I hope it will be enough to survive at least some beating… First flight in a few weeks since I'm still waiting for motors.

DemonRC NOX5 racing quadcopter is done

It took my time with this build, that is sure… Somehow there were always more important things to build. Anyhow, DemonRC NOX5 FPV racing quadcopter is finally up and running. DemonRC NOX5 quadcopter

What is inside? Nothing special:

  • Frame: DemonRC NOX5
  • Flight controller: Airbot Omnibus F4 v4 running Betaflight 3.1.7
  • ESC: DYS XSD30A BLHeli_S
  • Motors: EMAX RS2205S 2300KV
  • Camera: RunCam Swift2 2.1mm lens
  • Video transmitter: TBS Unify Pro v2
  • RX: FrSky X4R-SB
  • Propellers: DAL T5045C Cyclone

DemonRC NOX5 quadcopter

DemonRC NOX5 quadcopter

As a bonus, 3D printed TPU GoPro Session mount. But the bottom line is, it flies!

Hands on: DemonRC NOX5 FPV 5″ Frame

So many things to do, so little time… I’ve purchased DemonRC NOX5 quadcopter frame more than a month ago, but had some time to take a look at it only today. This is not a cheap stuff. More than a $100 for a 5″ frame is few times more than I’ve used to pay. But I just had enough of cheap chinese frames. Don’t get me wrong, they usually fly alright, but both quality and user friendliness lacks a lot. With “premium” frame at least I’m sure that I’m getting a good quality carbon fiber and someone actually thought for a moment about “tiny” details a place for VTX transmitter or battery strap…

So, please welcome DemonRC NOX5:

DemonRC NOX5 FPV quadcopter frame Read More

3D Printed RunCam HD / Mobius camera mount for Reptile X4R 220

After I finished my new Reptile X4R 220 racing mini-quad, I've realized, that there is no way I will be able to mount my RunCam HD on it. Comparing to ZMR250, 220 frame is just small. On a top plate there is enough room to fit battery, RC and FPV antennas and all what is left is around 35mm in the front. Plus, with angled FPV camera, there just no place for RunCam HD/Mobius form factor cameras. So, some time with 123D Design and few hours of printing, and here we are: 25 degrees mount for RunCam HD and Mobius camera specially designed for Reptile X4R 220 frame

25deg Runcam HC and Mobius Camera mount for Reptile X4R 220

This mount has 25 degrees inclination, will fit both RunCam HD and Mobius (not sure about RunCam HD2…) and its base is only 42x32mm. So it can be installed on small frames like 220. But, it will also fit bigger. No problems here.

25deg Runcam HC and Mobius Camera mount for Reptile X4R 220

The best way to install it on a frame is to use either zip ties or double sided velcro straps. There is a slot for 20mm wide velcro straps. To make it better, use 3M Dual Lock between.

To securely install camera also use 3M Dual Lock and use a velcro strap too. That should keep everything in place just fine.

3D Printed 25deg Runcam HC and Mobius Camera mount for Reptile X4R 220