The good and bad of the Sailfly-X and Red Devil
Happymodel have launched two of the better value toothpicks recently of which I have reviewed both - the Happymodel Sailfly and the Eachine Red Devil. Unfortunately both have minor niggles on the FPV side of things -
The objective of the mods:
Since the underlying powertrain of these quads is light and effective I set out to improve the above issues while trying to stay as light as possible. Also, in order to keep things simple I wanted to avoid soldering where possible to provide an easy and cost effective upgrade path for those who wanted to emulate the build. The result? I'm super pleased:
That Happymodel Larva-x is a great value bind and fly ultralight toothpick-style quad which I reviewed and provided and improved tune for here. This is their first model to come without a battery which is due to the fact that many international shipping suppliers are banning lipo batteries from shipment. Stock propellers are the Emax Avan Rush 2.5 but due to supply issues HQ Prop 2.5x2.5x3 are also included as spares. My full review is here where I flew almost exclusively on the HQ 2.5x2.5x3, not because they were necessarily better but because they were less stiff and transmit less impact to what is a relatively weak motor (see my review for more details including a response from Happymodel).
If you're new here you'll find I'm never satisfied with status quo and like to tinker. Propellers and batteries are dispoable items so I've chosen to share the outcome of my tinkering with these. What I did find however is that this quad is very sensitive to these combinations and although some improvements can be had, there are also some very poor combinations that are inefficient and noisy with less than stellar performance.
Recently I made my biggest ever FPV purchase - the Fatshark attitude V5 FPV goggles with the new 30 degree FOV OLED screens. I'm still field testing these for a review which will follow but first I wanted to look at the battery case, more to the point, how to fix the shortcomings.
In this tutorial I rectify this issue by showing you how to safely open the case and mod it to allow for real balance charging whilst losing noe of the rest of the functionality. With this mode you do not need a special charger for 18650 cells, you can use your regular balance charger and charge your pack safely and efficiently. If you need batteries a local vape shop will probably have the best prices but if not then I used these 3000mah ones that have been rebranded.
See below how to complete the work. This took me about 30 minutes. Most of the time was to figure out the best path for the wire and make the path for it accordingly. As always, pictures can be embiggened
The Diatone GT R249+ is my favourite traditional 2.5 inch micro quad based on it's relatively lightweight in this class, motors which have a wonderful mix of power and efficiency, reliable electronics and excellent built quality. My review of this quad is here and it is still available across multiple retailers.
However over a short period of time I started getting a lot of Jello which is concerning given the camera is a CCD which should be much more stable. I did a lot of PID and filter tuning but gave up after a while and let it sit on my shelf. Now I've come back to it with a fresh set of ideas and believe I have fixed the Jello problem once and for all. Firstly I can categorically state that in my case it was not the tune nor the propellers that fixed the issue as I've seen stated elsewhere. The issue is around the camera/VTX and this fix should be relevant to all canopy versions of this quad that doesn't use the TBS vtx i.e.
The screws that hold the vtx to the cam also hold the sensor board to the lens housing and I believe the connection between the board and housing is compromised as a result. At least the Caddx Turbo F2 has some foam tape between board and housing unlike the stock runcam swift although I don't believe a camera change is necessary.
Over the time that I have owned this quad I have improved and customised this quad to overcome some of the initial shortcomings and improve on what already makes this great. I have written several articles on this and have summarised these here with links to the full article plus any other improvements I've since made. Practically all of these upgrades are relevant for the Eachine Trashcan as well (which I reviewed here)
Since then I have found I prefer the V2 mobula frame which is the same design as the V1 but stronger (although not as strong as the V3). This is because I found it was easier to fit my favourite gemfan props and the overall flight characteristics were better, most notably decreased yaw washout compared to the V3. Note: the mobula7 v1 has been discontinued and all new mobulas ship with the V2.
Batteries and related upgrades
The Happymodel Mobula7 uses a F3 based flight controller and since Betaflight 3.4, these boards have not had full functionality of F4 and F7 boards due to smaller memory size for firmware storage. However in this article I will cover how to upgrade to the performance edition of Betaflight 4.04 kindly compiled by UAVTech (his in depth YouTube Channel is here). This special version adds the key performance functions at the cost of typically irrelevant features like servo control, acro trainer, camera control etc. In this article I will show you where to access this firmware and then I'll show you the filters that suit brushless whoops best as well as some good starting PIDs.
This is the seventh and likely final article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
Betaflight 4 Performance edition for F3 boards
This is the final version of Betaflight you can use and I strongly recommend you use this version rather than the one on the Betaflight configurator to get full performance functionality otherwise you will miss out on features like:
The Happymodel Mobula7 (reviewed here), Eachine Trashcan (reviewed here) and many other brushless whoops use generic 4 bladed 40mm props that are cheap and readily available but are they the best? Simply put, no. They are from a toy grade mould and we have accepted them because when these brushless whoops were first released there was simply nothing else available. Fast forward to the present day with the growth in popularity of these models there are a lot more options, some readily available internationally, some not so much. In this article I'll give you my experiences on what I found to be my favourite prop and the justification of why (what it is I look for in a propeller).
This is the sixth article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
What props are available?
If you're in North America probably the full list of what is below. I'm not in North America though so I was limited to what was locally available and what had low (or no) international shipping cost. Therefore this is not an exhaustive test, my approach was more on of pragmatism.
I'll compare all my findings back to a baseline result of the stock props for simplicity
Gemfan 1636 (4 blade)
I used these when I was running the v3/trashcan frame which I blogged about here. These were a direct improvement over the stock props in all aspects but were a little more amp-hungry. Grip and speed was improved and control felt better. Props are well balanced but heavier than stock. They are extremely durable especially when you consider the protection afforded by the ducts. You will achieve hover at very low throttle
These props are a good upgrade but not my personal favourite.
Note: These are more like 41mm than 40mm and frustratingly don't quite fit in the ducts of of the v3/trashcan frame - the ones you see above were painstakingly sanded down and even then still rubbed every now and then. I hear TBS props have the same issue
The Happymodel Sailfly X is my favourite quad I've reviewed so fat this year (review is here) but as with any product, there are shortcomings especially when is it built to a price. Like I did with the Mobula7 I'm starting a new series of articles on upgrading and customising the Sailfly-x.
Step 1: Software only
The most simple mod to do is ensure the onboard receiver is given an armchair ride from a software standpoint. This means changing D16 to D8 mode in betaflight and turning off telemetry which has been known to lock up the flight controller. This can be done as below.
Voltage sensing is critical in Betaflight not least of all because it is the best indicator of when to land in order to protect your batteries to make them last longer. I've always taken for granted that this reading is correct on every board from the factory but I can tell you it is not. On 2 recent quads I've set up it was well out (Happy model Sailfly-x and my 2019 freestyle build) to the point were it reported my 6s battery as being 24v instead of 22v.
First you'll need to connect your quad to betaflight and enter the "power and battery" tab. Next plug in your battery (please do it in this order). With you battery plugged in you'll see the voltage as shown by betaflight in the area highlighted below:
Next use the digital multimeter to test the battery voltage using the balance connector. Do this by touching the multimeter probes on the terminals at the extreme edges of the balance connector as below. Don't worry if on backwards, your multimeter will just report a negative voltage which is fine. It is important to do this whilst the battery is connected to the quad as the electronics (especially the VTX) will draw a small amount of current and thus cause the voltage to drop a little compared with having the battery disconnected.
Both the Happymodel Mobula7 (review) and Eachine Trashcan (review) both come with 4 x 1s batteries that are designed to be used in series 2 at a time with a fiddly ph2.0 series connector. This introduces a lot of resistance in the power circuit and resultant voltage drop under load which shows as battery sag. It is easy to upgrade to a true 2s JST connector as I've shown in this blog or a XT30 if you'd prefer. Although 2s 300mah batteries are not expensive it does feel wasteful just leaving the old batteries to die. This article covers how to convert these or any other 1s cell into a 2s battery and is scaleable up to 6s!
This is the fifth article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
A Word of Warning
Lipo batteries - even these tiny ones - have a lot of power. Anytime you modify you run the risk of rapid discharge (shorting) which generates heat and possible worse. Only do this mod if you are confident around electronics. Please wear eye protection at a minimum and work in a well lit space. Just go buy the 2s batteries if you are unsure at any point.
As well as having a well lit area and a good soldering iron, solder and flux (see my article on budget tools here) you'll nee the following items:
In order to solve the charging issue FullspeedRC (yes the same ones that launched the Leader series of micro quads) have released a simple board that allows the batteries to be balance charge using the existing USB port. It can be bought for around $10 at the following retailers:
Please note this is not a beginner install but if you can solder a FPV cam and vtx to a flight controller you can probably do this. I've put in a LOT of photos and steps in below to make it as straightforward as possible since Fullspeed's manual is accurate but overly short. As usual click any image below to embiggen.
Tools I recommend for this job:
I promise I'll keep this one short. We are forever taking antennae on and off our quads and goggles as we arrive and leave our flight locations. I'm guilty of being too eager to get in the sky and not tightening my antennae correctly thereby leaving a poor connection to the active element on both the quad and goggle ends. Using a spanner is not a fix I'd recommend as it is easy to over-torque and damage the antenna or mount.
The fix here is really easy and I got the tip from my favourite VAS antennas which all include a plastic knurled grip (now I know why). Using a knurled grip that sits over the hexagonal drive on an SMA-style connecter allows you to get a better grip and more torque on tightening whilst avoiding over torquing as above. To put this another way - using these grips allows you to get the right tightness every time - good for the best connection and it will also help them coming loose in flight.
I love the emax tinyhawk, even though it is 'only' 1s it is well suited as an indoor racer and they've recently started a spec class near me just for this. My full review of it is here. One one common furstration however is that the FPV camera can come loose in a crash and if you try to push it back in the wrong way you can easily snap the tabs on the frame that hold it in. I've prepared a simple step by step walkthrough heretht will allow you to fix it safely in less than 5 minutes (I timed it!).
The Emax Tinyhawk is a 1s brushless whoop-style quadcopter that has steadily grown on me since I first reviewed it here. It's certainly not the fastest but is probably the most well designed ducted quad available at present. It comes stock with very good 3-bladed emax props that perform well except that lack thrust when running in reverse meaning "turtle mode" does not work. I've installed and reviewed their new 4-bladed props where turtle mode works and how they perform in general.
Reversing the rotation of all of your propellers (known as 'props out') is something you commonly do on larger quads to eliminate debris bring flung into your FPV camera and to push obstacles like branches clear. Obviously these don't apply when the props are gaurded like in a Mobula 7 but there is also a hypothesis out there that it can improve flight characteristics such as note on KababFPV's video here. Some of the beta fpv guys also believe it helps with yaw washout but the evidence appears inconclusive. Typically to do this correctly you need to
This is the fourth article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
The crazybee F3 and F4 series of all in one boards that are the heart of the mobula7, m7hd, eachine trashcan, snapper7, ur65, uk/us65 and even beta75pro2 are an amazing piece of technology that incorporates a flight controller, 4xBL_HeliS ESCs and a receiver. Cramming all of this on one board does mean some compromises though and the biggest one for me is the poor receiver range. This brief article will show how to get a minor improvement with zero investment. Note: this mod is relevant for all the models listed above.
This is the third article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
In order to run 2s, the Mobula 7 comes standard with 2 x PH2.0 connectors that allow you to run 2 x 1s batteries in series. When running in series the strength of the connection is determined by the weakest link in that circuit. The strength of connection determines the maximum current that can pass and the voltage drop that results. Although it works this system has a very low current overhead from a design perspective - 2 x budget PH2.0 connectors with the dreaded 'folded' pin and very lightweight 26AWG wire. All this adds up to a lot of voltage drop when even reasonable current is pulled - something all will be familiar with on the mobula where you see voltage drop to scary levels (6v and below) during punches even when you have a full battery. Although it recovers almost immediately it does mean you don't get access to the battery's full voltage potential.
This is the second article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
Introduction and why I like the Mobula7 better.
It's been a few months since I reviewed the HappyModel Mobula 7 (here) and have more recently reviewed the Eachine Trashcan here. Since reviewing the Trashcan I've been flying the Mobula 7 more and find I actually prefer it. Why? Even thought the image quality is better I can't get used to the narrow vertical field of view on the traschan's EOS2 16:9 camera and I find the 0803 motors on the trashcan draw too much power on without delivering a whole lot more speed. The Mobula7's major downside is the frame which breaks easily even though the v2 frame is an improvement and e6000 glue (as tested here) is great for repairs.
For this reason I've written an article for newcomers on how to upgrade to the V3 (trashcan) frame which completely addresses the strength issues.
This is the first article in my series of HappyModel Mobula7 upgrades, many of which can be used for the Trashcan too. Also to come are:
Instead of just writing about it, please see the steps below with captions. Click on the picture to embiggen
Recently I've reviewed the Eachine Trashcan and in many ways it is superior to the Mobula7 as I found in my review here. One omission from the trashcan though compared to the Mobula7 is the lack of a physical beeper. On the upside though is that the trashcan (like most other brushless quads) uses Dshot as the ESC protocol meaning you can use the motors as a beeper. This is in fact immediately available on the Trashcan with some simple software changes which I will outline below.
I did a thing. After reviewing the new FullSpeed TinyLeader 2s-3s brushless whoop (review here) I learnt to fly around the heavier weight which has come about because of it's larger motors and better FPV system. I still think that 1103 motors like on the TinyLeader and Beta75x are better suited to a lightweight 2" propeller like my ultralight build here rather than the 40mm props (1.6") as we see so commonly on the brushless whoops now. I decided to put my money where my mouth is so to speak and prove it rather than just hypothesing.
To those of you that choose to upgrade the vtx in your hawk 5, like I did with the AKK infinite VTX/DVR (in this walkthrough here) I've updated my recommendation for the powersupply. Previsouly I relied on the flight controller's 5v BEC circuit that also powers the receiver and of course the board itself. I've now updated this recommendation to use the VBAT (or VCC) power supply instead assuming of course your VTX can take up to 24V as most modern full-sized VTXs can, including the AKK infinite I installed. This is because the BEC struggles at higher output making the video feed noisy. Over the longer term this is likely to irreversible damage the BEC rendering the flight controller pretty well useless but not before having random failures as a result of the compromised BEC. Picture below is using the power supply from the original VTX - the flight controller's 5V BEC:
There is no doubt that the mobula7 as reviewed here is an excellent quadcopter that has redefined what ducted micros can achieve at a fair price but the key flaw in this model (and other ducted quads) is lack of durability in the frame. Frames for the Mobula are not expensive at $4 here but waiting on a frame to be delivered represents downtime.
Welder's glue is often recommended but is not available everywhere and shipping can be precarious on this. I tried the E6000 glue from banggood on a whim and am really please to report it works perfectly, is inexpensive and being available from Banggood, is available worldwide. It comes 15ml, 50ml and 110ml tubes for $3, $4 and $7 repsectively at time of writing. 15ml is plenty for the small amount we need for repairs. It also has a very fine metal nozzle which is just perfect for the fine work we do on repairs. The cap has an integrated pin that sits inside the nozzle for storage so never blocks.
The Taranis X-lite brings a whole new level of portability to FPV transmitters thanks to its compact design and I found this to be one of the most surprisingly useful features of this controller in my review.
The x-lite comes with a very nice lightweight zipcase as you can see in the picture below which allows you to stow some spare parts too. For quick FPV missions though I find all I need is the controller though but the gimbal protectors that come with the controller are just too loose to stay put if I put the controller in my bag without the case. Hence I've been on www.3dhubs.com/he lookout for some gimbal protectors that not only hold more snugly but also protect the screen. There are a number of designs already avilable on thingiverse if you have a 3d printer or access to 3dhubs but what if you just want to buy a cheap solution that does this for you?
The Emax Hawk 5 is arguably the best bind and fly quadcopter going as I found in my initial review but can also be greatly improved with a few budget modifications as I wrote about in my blog on bang for buck improvements. I do however see a number of people complain about the stock Emax Hawk 5 vtx however mine has been functioning well. That being said, you cannot adjust setting in betaflight OSD via smart audio or tramp telemetry which is a let down on a 2018 quad. In the interest of sharing I've removed the stock VTX and replaced with one of the larger VTXs currently available (the AKK Infinite VTX/DVR) to prove it can be done.
The VTX I chose is the AKK Infinity DVR VTX. This is very similar to the HGLRC VTX/DVR that was reviewed here. As the name suggests this is a smart audio VTX in 30.5mm VTX with a built in DVR. I chose those for 2 reasons: First it's big. If I can fit this in you can fit anything! Secondly I like the DVR for recording breakup-free footage. For me I like the nimbleness of the Hawk 5 and don't want to weigh it down with a HD Cam. Other key features of the VTX/DVR:
Just quickly I used the following tools and parts in the instructions below:
Please note all the pictures below relate to the install of the AKK Infinite but install should be identical or at least nearly the same for others. I had to remove the buzzer and relocate the receiver for this VTX but depending on the size of the VTX you install you may need to do only one or neither. Follow picture left to right then down. All pictures will enlarge if you click on them.