General questions about SPEKTRUM receivers
Firmware V5 for AR7210BX: Why do I have to pay for it? What benefit will I get?
After updating your device to firmware Version 5.x.x you can do all the setup with your computer or smartphone in combination with the StudioXm App and USB2SYS/BLE2SYS interface. There is no need to do adjustments at the device using the button and the LEDs anymore (which of course is still possible to do). Additionally you can backup/restore settings, load predefined settings (currently for ALIGN TRex helicopters only), read out log data and perform a vibration analysis. As we developed the firmware and app independently from the manufacturer Horizon Hobby and did put a lot of effort in it, we charge 20 Euros for this update/upgrade plus you need the USB2SYS serial interface for the computer or BLE2SYS bluetooth interface for connection to the smartphone/tablet. In case you already have bought the PROEDITION firmware you've already paid for getting firmware from us, so you get this update for free as part of our product care. If you're not interested in the new functionality or do not want to pay anything just stay with your stock firmware V4.x.x. There is nothing wrong with it and you can still get support from Horizon Hobby.
The AR7200BX that came with my Blade helicopter is not supported in StudioX
AR7200BX with special Blade firmware on can't be programmed using StudioX as they are configured specifically for the helicopter they are installed on. Nevertheless, you can update the firmware using StudioX and make a "full" AR7200BX out of it, so that it can be used with StudioX. But note that you’ll have to use the original AR7200BX manual to setup the device in future. A factory reset will NOT revert to the Blade preset then!
To keep your existing Blade settings it it important to update to firmware version 3.1.0 only, as this will not delete your setup. Once 3.1.0 is uploaded to the device, it will be recognized by StudioX and you can create restore points, change settings and more. So create a restore point of your device and then update to 4.0.14, if necessary. Updating to version 4.0.14 will reset your settings as 4.0.14 uses a new parameter set. But as you have created a restore point before, you can recover your setup and only have to setup the additional governor parameters.!
Which servos can be used with AR7200BX/AR7300BX/AR7210BX
A rule of thumb to find well suited servos for you flybarless helicopter: As strong as necessary, as fast as possible, with less dead band as available.
Servo torque in kg/cm should be at least 3-4 times the heli weight (in kilogram). Speed should be at least 0.1s/45°. The faster the better. In addition the servo should be very precise, have little gear backlash and a low dead band. And of course it should be a digital servo that supports high frame rates (200Hz or more). Also using special heli servos which are designed for maximum vibration resistance is a good choice.
Note that all the speed is useless if the torque is not enough. In doubt when two servos of a series are only slightly different in speed and torque, normally the more powerful is in advantage.
Anyhow, if in doubt ask the manufacturer of the servo if it can be used in combination with flybarless/gyro systems. Not all servos can handle the additional stress of getting different control signals every few milliseconds. Also it must be said that not all servos can be used at maximum frequency even if so it is told on the servo's data sheet. Depending on air temperature, voltage level and heli size it is possible that servos can not be driven at their limit as the servo motor or electronics may heat up too much.'
AR7200BX vs. AR7300BX
I intend to use a BEASTX flybarless system on my 600/700 heli. Should I go with the AR7300BX?
Today's servos and especially so-called high voltage servos typically have a very high power consumption. When using Futaba BLS 451 servos for example these are very modest. Savöx 1258/Align DS610 are much more demanding, one alone taking up to 15Amps peak for the instance of a second. And for very extreme example take high voltage Savöx servos SB-2271SG HV. They demand up to 27Amps (1 Servo!) peak which you can see when measure the power consumption with an oscilloscope.
So besides using a good stable and high rated power supply you have to ensure proper supply of the servos with this power. But when only connecting one servo plug with power leads into the receiver this may insufficient and cause a "bottle neck" in power flow. There is no benefit if the power supply/BEC itself can deliver 20-25A when this amount of current is not able to flow to the consumers.
So the idea behind AR7300BX is to provide a power connection that allows for using thick power cables and directly connect these to the device, so the voltage loss due to wiring and plug connection is reduced to a minimum. In general for helis with standard size servo you should always use AR7300BX, because this will eliminate the "servo plug problem" as one important factor that may be critical for your power supply.
Anyhow, it mainly depends on how you power your system. I. e. when using an ESC with only one BEC line (and if this works without issues), then there will no benefit of using the AR7300BX as you already have a "bottle neck" at the power output. The small wire will not be able to transfer more than 5 Amps continuous current. Connecting this little wire to AR7300BX's high power input will not help very much here.
If on the other hand you have at least two or even three BEC lines then this can be different as you may solder the power wires from the BEC together to a EC3 high power plug. Then you have a much lower contact resistance compared to only connect the wires using the standard servo plugs, which is a real benefit for providing a stable power supply. Ideally you have a BEC or receiver battery that already comes with thick power wires. Here it is ideal to use AR7300BX.
When using a separate receiver battery i.e. on nitro or gas helis using AR7300BX is the ideal way to connect the battery to your RC system. In addition to the adequate connection plug here you have an integrated switch system for switching the heli on and off, so there is no need to buy an extra switch.