Written by Mark Christy Monday, 08 February 2010 16:07
Robbe have recently added a new series of models to their Roxxy range of ESC's. These new models are aimed at the growing number of larger electric models operating on 12S setups.
Here we have the 9100 (No.8640) model which is rated at 100Amps continuous and 120Amps peak. There is also the 9120 (No.8641) which is rated at 120Amps continuous and up to 150Amps peak. Finally to complete the range there is the 975 (No.8639) which is 75Amps & 85Amps respectively. The controllers feature the latest Cool Power FET technology, noise filtering & suppression, 32KHz high frequency motor control and the 9100 & 9120 models both feature intelligent cooling fans. All 3 ESC's work with 4S to 12S LIPO batteries or 14 to 36 cell NIMH/NICADs.
The controllers can be programmed directly from the transmitter or more easily from a handy little control box available separately (No.8642).
The ESC features all the traditional safety mechanisms of power down on signal failure from the transmitter and arming only when the throttle is at idle.
The ESC itself is a reasonably large unit owing to the integral fan (see picture comparison with Castle Creations 85HV). The fan does not operate all the time and only comes on when the current draw rises. However as this is being mounted to a 90 (Trex 700) size model the size is not too much of an issue.
I have mounted the ESC in conjunction with an EMCOTEC safety switch. This allows me to connect the batteries up without making the speed controller go live. The safety switch also does away with all the arcs & sparks associated with the high voltage batteries. Once the connections have been made the magnetic plug is simply removed and power flows to the ESC. This setup allows you to have a hand free just like a nitro model to hold the rotor head incase of any startup "incidents".
Setup of the Roxxy controller is very straight forward. The first task is to tell the speed controller where full throttle and idle are. To do this you turn the model and your transmitter on and put your stick to full throttle. Then you turn on the ESC. After 10 seconds you will be given a notification tone to move the throttle to idle. This will be followed by another tone letting you know the calibration is complete.
If at the start of this process the LED comes on on the ESC then your throttle needs reversing on the transmitter.
As mentioned earlier the ESC can be programmed via the transmitter stick inputs but a programmer is available separately to access a greater variety of functions and to allow a quicker easier setup. This is the unit I used to setup the Roxxy for this review.
To program the ESC with the programmer is again a very simple task. It features four buttons (Up, Down, Plus, Minus). The Up & Down buttons are used to scroll through the options and the Plus & Minus keys to adjust their values. A nice touch is that there is a separate lead for the programmer so you don't have to disconnect anything on your model to use the programmer and make changes.
To put the ESC into programming mode you attach the programmer and then apply power to the ESC with the radio turned off.
The ESC has 3 operating modes (Air, Helicopter, Boat/Car). Pressing the Up & Down keys together allows you to choose which mode you want. For obvious reasons we will concentrate on the Helicopter settings!
Once the correct Model Type is selected the next option is the Battery Type. This was left to the default of LIPO. The next two items where the Cut Off Voltage & Type. These features shut down the ESC when the battery volts fall below a certain threshold. They were also left as default to auto detect the correct voltage and shut down in a soft manor. Motor Direction was left as Normal and the Advance Timing left at 15 degrees as recommended for out-runner style motors.
Following on were two important options if you want to keep your gear train in one piece. The first was Acceleration which governs how quickly the motor can ramp up to speed. Too fast and you'll strip your main gear. This was set to "Normal" out of a range of Lowest/Low/Normal/High/Highest. As I run the throttle delay on my Futaba 12FG this item isn't really important, but for those without this transmitter feature it can be very useful so as to reduce the shock on the system when transferring from hovering head speed to aerobatic head speed. The second related item was the Start Power option. This is very similar but governs the speed ramp from stationary, otherwise known as the Soft Start function. This I set to "Lowest".
The ESC then allows you to set the Governor operation. I have this disabled on my ESC as I run my large electrics through a traditional governor which I'll cover later in the review. However the in built governor function is much like many others where it interprets your throttle percentage as an RPM request and tries to hold the motor at that RPM. The final three items are the Pole Number, Gear Ratio and RPM recordings. Setting the Pole Number and Gear Ratio allows the ESC to log your maximum and average RPM's during the flight.
To allow me to set accurate multiple head speeds from my transmitter I use the ESC in conjunction with my Curtis Youngblood ATG v3 governor. To do this I run the throttle lead of the ESC to the governor just as if it was a throttle servo. However as there is no clutch or fan to mount the sensor magnet I fit the magnet to the main gear and set the ATG gear ratio to 1:1. Finally I turn down the ATG gain to stop any hunting on the ESC. My installation can be seen in the pictures. Having the governor function linked with a slider on my transmitter I can easily adjust the models RPM in flight.
The first thing that was apparent in comparison to the Castle Creations ESC I had installed earlier was that the soft start was noticeably softer. The ramp up to flying speed was smooth with no qualms. In flight the controller worked without issue, smoothly changing from RPM's as demanded and shutting down cleanly when entering throttle hold. Some controllers are unhappy when not running at their maximum but there was no such issues with the Roxxy unit. Working in conjunction with the ATG there was no hunting or gear chatter at any of the head speeds I flew at (1400rpm & 1850rpm).
A nice feature is the recorded average and maximum RPMs. Using the programming unit I was able to check these at the end of a flight. The maximum recorded rpm was 1905rpm which is close to my desired aerobatics head-speed and would have occurred when unloading the motor during turn arounds and is to be expected. Also I do not run a high gain on my governor and let it run more like a RPM guidance unit so that there are no sudden corrections on the model that could be hard on the transmission or tail/gyro. This feature is a great sanity check that all is working correctly on the governor front whether using the built in governor or an external unit.
The new Roxxy ESCs arrive at a price that places them in between the Castle HV units and the Kontronik Jives. However the price does put them closer to the Castle Creations than the Kontroniks. A premium price such as this requires a premium product and I have no doubt that the Robbe Roxxy fits this bill admirably. The unit is well made, easy to operate, and has performed flawlessly in a wide range of operating speeds without a single hiccup. The high end 12S helicopter ESC market has a new great selection of controllers to offer with the Roxxy BL9X00 range.
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