The Riot electric trainer type model from Century UK (aka Red Devil in the USA) is quite a tame model to fly which in turn enables novices to get into the air quite quickly and also a quick, car boot model to thrash around for experienced flyers. An article on the Riot has been previously covered and can be found on the website. As an OEM it is quite useable and the ability to replace parts or repair the model is always an advantage especially for new pilots. I have written this article in response to our members who have purchased this model and have requested information on the upgrade. The Club's Riot trainer has also been upgraded.
We have to bear in mind that this is a Far East model at relatively low cost which will also include low to middling components, more precisely the motor and ESC. Having said that, many have had no problems but of course you always hear the downsides first. Magnets coming loose on motor and ESC failure. The servos will be included in this scenario and I advise to never operate the control surfaces agains the servos - you will strip gears! *Note that the wing servos should be bought in pairs even if one fails.
Let's get on with the upgrade. The components selected, see below, are my personal choice having used them for many projects, fair price and mostly reliable. I have published the sources for these items purely for you to peruse and I gain no profit or back-handers from the suppliers. However, you may have alternatives in mind so at least you can make a comparison. The cost of the components including the a larger Lipo battery I used came to about 60% of the original cost of the model.
Removing OEM Power Train
First job is to remove the prop / spinner. Save these items in case you wish to re-use them later but I upgraded the prop and spinner too! Using a small cross head screw driver undo to very small screws found recessed in each side of the cowling. Carefully pull off the cowling. We are now looking at the motor unit sat in the nose of the fuselage. There is also a ballast weight, a block of steel weighing 65 grams. It is only glued in with UHU so carefully dig it out. You can keep it if you wish but it will not be needed as the larger battery in the upgrade will compensate for this.
From the topside of the fuselage unplug the throttle lead from your receiver and gently pull the lead back through it's tunnel into the ESC area located under the battery compartment. The ESC ( electronic speed controller ) is not secured in the fuselage but just lays in the bay.
Moving back to the front undo the four screws that secure the motor to the firewall. Depending on which Riot model you have, Red standard or Blue (limited edition) these screws may have washers under their heads or oversize heads and looking at the model from the front the top right screw will have a washer behind the motor's integral bracket. Retain this also, as this gives the Riot motor some right thrust and down thrust of a degree or two.
You should now be able to pull the motor carefully forward enough to unplug the ESC at the 3.5mm bullet connectors. Now we can remove the ESC by pulling it back through the front gap where the wing locates. We now have a fuselage ready to upgrade.
Preparation Prior to Upgrade
Depending on which version you have the battery is slightly different. The earlier Red model has a full slotted battery compartment floor whereas the later Blue version has no plastic floor, the latter making it slightly easier for us.
The original motor wires passed neatly behind the raised motor bracket but our motor bracket, an X type will lay flat against the firewall. This entails creating another way of getting the motor wires to the ESC behind. I used a 4mm drill and bored three holes at the bottom of the firewall allowing the drill to cut into the foam behind - but take your time and go carefully. You need to drill above the slot where the ply fuselage floor locates into the firewall. There is also a screw centrally fitted, leave this intact. In fact I drilled two 4mm holes, one on one side of the screw (not too close though) and one the other side. This will get the three motor wires to the ESC behind. I then proceeded to clean the holes out a bit and verifed that the new motor's bullet connectors will pass through. Note: If you have the Red version you may have to remove some of the plastic battery compartment floor to allow the motor wires to pass under into the ESC compartment. If you have the Blue version then the wires will just sit on the front of the ply floor before passing underneath. On the latter this will not affect the installation of the battery as you have slightly more depth to play with.
Taking the aluminium X motor mount supplied with the Emax you need to drill out the four outer mounting holes to 5mm. This will enable the use of the original firewall holes, the larger holes allowing the X plate some movement and to aid fitting. Verify by a "dry run" that all four screws holes are accessible through the enlarged X plate holes. If not then just wiggle the drill back through the holes a little until they do.
Fit the motor to the X mount using the short machine screws supplied. You may wish to put a drop of thread lock on these although I found once installed they did not vibrate loose - vibration being minimal on electric powered models assuming your prop is balanced.
Grab the ESC, I am assuming you have soldered the supplied or correct size bullets to the output wires to match the motor's. This bit is a bit fiddly but has to be done. Place the ESC into the forward compartment where the original was removed. Using whatever method you prefer bring the three ESC wires towards the firewall close to where you drilled out. Bring the motor wires through the drilled out holes and plug them in. The Blue version is easy but Red owners will need to use long nose pliers (I had to anyway) because you havethe battery floor in the way. See images.
At this point I did and highly recommend (Red version owners especially) that you fit the motor with just two opposite location screws to firewall and lightly tighten, pushing the power leads backwards at the same time. What we need to do now is to verify the direction of rotation of the motor before proceeding further. Fit the shaft adaptor, it will stay on from now on, and won't hinder the upgrade. Now fit your chosen prop and just nip it up firmly. I suggest this as it is better to check the direction of rotation before screwing everything into place then finding you have to go back a few steps to swap motor leads around!
Retrieving the throttle lead from the ESC, plug it on to the throttle pins of your receiver. Using a three cell Lipo, possibly your original one power up the ESC, ensuring the throttle stick is fully down. You should now get a tone, then a series of tones confirming number of cells (3) and then a long tone informing you that it is now "armed" or ready. Move the throttle stick up little until the motor starts to turn. Looking at the front of the model, does it rotate anti-clockwise? If so then nothing futher needs to done there. If rotates clockwise, then for Red version owners you possibly will have to fiddle around a bit to switch wires. Remember to unplug the Lipo FIRST, don't work on a live plane! If rotation is correct you can now ensure the power connectors are fully engaged and secure.
The motor can now be fixed using the original screws but may need slightly larger flat washers under the heads due to the enlarged X mount holes. Also I recommend a few drops of thin CA into the firewall screw holes to harden them up and give the screws something more substantial to bite into. REMEMBER to relocate the single washer under the X mount at the top right hole Remember "right thrust, etc".
With motor secured, the ESC is laying in the forward compartment and the ESC input leads should be just poking through the rear of the battery compartment. The throttle lead now needs to be located. I must admit I found it nearly impossible to get it back through the original tunnel so I opted to make a slot in the top of the fuselage and pushed the lead into the slot and then down to the receiver. See image.
You now refit the Riot's cowl using the two small screws. Assuming you have fitted the shaft adaptor correctly and it is pushed fully home you can now place the spinner backplate on to the adaptor, I used a Irvine spinner with an aluminium backplate, then the APC -E prop and then the nose cone itself. You will find that the rear of the spinner is a bit further away from the cowl than the original but this small problem is insignificant and probably not noticeable by most.
That's it! Done!
On static test using the items listed below and an APC 12 x 6, the input power to the motor was approx 495 watts using the Nano-Tech 3300maH Lipo ( lithium polymer battery )
It flies well and takes off in with a very short roll-out although I prefer scale like climb outs. Has been flown in winds around 12 to 15 mph although being a very light model you need to take off directly into the wind otherwise a side wind will steer it where you didn't want to go! Will fly big loops and with high rates on control surfaces a little bit more exciting. On low rates quite docile and predictable. With reasonable throttle management I get approx 8 - 10 mins flight time bringing the LiPo down to about 20% charge left. With little or no wind it does comes into land a little bit faster so be aware of this.
Cost of Upgrade - *as of Jan 2014
- Motor - BL2820 - 07 - BRChobbies = £17.95
- ESC - 60amp with BEC - Hobbywing = £27.99
- Prop 12 x 8 - APC-E - Various = £3.25
- Spinner - Irvine - Various = £4.75
- 3300maH LiPo - Hobbyking = £24.95
Since the upgrade I have discovered that the motor X mount screws needed changing. Although the Riot has had regular weekend use and more throughout 2013, I found fortunately whilst still on the ground, that the motor mount screws had worked loose in the firewall, in fact two where missing completely. A clue was the prop appearing to vibrate! To rectify this I have since replaced the original screws with slightly larger broad head self tappers, again hardening the holes with thin CA.
- Type: EMax BL2820-07
- Class: Brushless
- KV (rpm/V): 919
- Number of cells: 3S to 4S LiPo (11.1V to 14.8V)
- Maximum current: 45A (for 60 seconds)
- Constant current: 35-40A
- Dimensions: Diameter 38mm, Length 46.9mm
- Shaft diameter: 5mm
- Weight: 145g
- Recommended ESC: BRC 60A Pro
- Prop range: 3S LiPo APC-E 12 x 6 (400W) up to APC-E 12 X 8 (410W)4S LiPo APC-E 10 x 5 (400W), APC-E 11 X 7 (460W), APC-E 12 X 6 (530W), APC-E 12 x 8 (560W ** ensure adequate cooling and good throttle management)
- Recommended for models up to 2.4Kg/5.3lb AUW
Supplier - BRCHobbies
HobbyWing Pentium 60Amp Brushless ESC
- Output Continuous 60A Burst 80A
- 2 - 6 cells LiPo
- BEC 3A / 5V switch mode
- Refresh rate throttle 50 - 432Hz
- Max Speed - 21000 rpm -2 poles BLM. 70,000 rpm - 6 poles BLM. 35,000 rpm 12 poles BLM
- Weight 63 gms
- Safety Arming.Regardless of throttle stick position, the motor will not spin after battery connected.
- Throttle calibration function: Throttle range can be calibrated to be compatible with different TXs.
- User programmable.
- Multiple program methods supported: transmitter stick, LED Program Card
- Compatible with Lipo battery and NiCd/NiMH battery.
- Internal timing can be changed to be suitable for different brushless motors.
- Full protection: Low voltage cut-off protection/Over-heat protection/Throttle signal loss protection.
- Extreme low resistance PCB is used at the power output.
- Microprocessor uses separate voltage regulator IC, with good anti-jamming capability.
Supplier - GiantShark RC
including Alternatives which fit battery bay.
LoongMax Tipple 3000maH 3 cell 11.1v 20C
Turnigy Nano Tech 3300maH 3 cell 11.1v 25 - 45C
Prop and Spinner
APC-e 12 x 8 or 12 x 6
Irvine Spinner 51mm Colour? Your choice!