I was interested in building a thrust vector jet and decided on the SAB AVIO Drake. This plane does not need a full build thread as the manual and build are very straightforward. I wanted to share my experience with the build and maiden flight for others considering getting into an affordable 3D capable turbine jet.I ordered everything needed for the build from HeliDirect except for servo arms and the turbine. The box that arrived was well packaged with no damage to the contents.
SAB AVIO DRAKE's Components for the build
SAB Antartica KR175 Drake Jet Kit (SAK175)
SAB Avio Landing Gear Retracts with Unit (S0084-S)
SAB Avio Landing Gear Legs (3 Legs) (S0083-S)
SAB Avio Landing Gear Wheels / Brakes (3 Wheels) (S0085-S)
PowerBox Mercury SRS (4120)
TORQ BLS2208 Full Size HV Brushless Servo x 6 (BLS2208)
TORQ CL1208 Mini HV Coreless Servo x 2 (CL1208)
PULSE 5000mAh 2S 7.4V 15C - Receiver Battery - LiPo Battery x 2 (PLURX15-50002)
UAT 120CC (S0296-S)
KingTech K210 Turbine or The Rhino 200 SE Turbine Engine (JCTRHINO)
The kit comes with gear doors than are optional for your build. Three servos are needed to control these doors. The sequencer is included with the brake controller in the Gear Retracts. A good servo choice for the doors is the TORQ CL0508 Micro HV Servo.
The manual is excellent. I have built four jets and helped build a few more and SAB does a great job with the manuals. Each step shows what to do and references a numbered bag of hardware for that step. I have built many SAB helicopters and this kit follows the same great standard. I did vary from the manual with the gear install for the mains. I prefer to tap and harden the mount points for the gear instead of the metal plates they provide. If I have a hard landing I would rather strip the screws instead of rip the mounting blocks out of the wing.
Retracts and Brake Setup
The retract set comes with a controller that drives the retracts, has a gear door sequencer, and brake controller. The wheels also come with a brake controller. The controller build into the retract unit only supports on/off for brakes or a pulsating on/off action. The controller that comes with the wheels is proportional and works well. I used the proportional brake controller for braking and the gear controller for the retract operation. The manual does not discuss the proportional controller but I recommending using it.
Electronics setup with a delta wing, thrust vectoring, and canard were new to me. I have used the PowerBox Mercury SRS (with iGyro built in) for other builds and used it for this as well. This gyro has two gyro channels (servo outputs) for elevator, aileron, and rudder. The Drake is a delta wing so I setup the iGyro as a delta wing type. This uses one of the elevator and one of the aileron gyro channels.
To setup all controls to be gyro controlled on the Drake you would need:
4 Yaw gyro channels (two rudders, yaw thrust vector, and nose wheel steering)
3 Elevator gyro channels (one for delta wing, canard, thrust vector)
1 Aileron (delta wing)
With the iGyro the closest I could configure was:
1 rudder for yaw thrust (I don't put a gyro on the nose wheel as a personal preference)
2 elevator (delta wing elevator, thrust vector) canard has to go without
1 Aileron (delta wing aileron)
The two rudders need separate channels to support toeing in both rudders as an airbrake. The mixes for this are opposite for the two rudders so they cannot share a rudder a or rudder b channel)
The canard I tried to use with the thrust vector control using servo matching in the Mercury. I could not get a set of endpoints that controlled the throws I wanted. I ended up using a curve in the transmitter for the canard and not going through a gyro channel.
The Cortex Pro gyro (BD-CORTEX-PRO) is able to support up to 16 stabilized channels that can each be assigned to a surface. this should allow the flexibility to setup all the possible combinations on the Drake.
After flying the model I do not think that more gyro control is needed. With the iGyro configuration the model flies in windy conditions with no issues. Either of these gyro configuration will provide good results!
Ready To FLy!
I setup the aircraft per manual and then backed off the low rates a small amount just to be safe for the first flight. The CG I set per the manual The first flight was perfect. I can highly recommend this jet for sport flying. This is my first thrust vector jet and it is recommended that it remains on at all times. The setup works great this way and I recommend not turning off the thrust vectoring in any flight condition.
Impressions of first flight
This jet is very hard to tip stall. The canard also moves the pitch rotation farther forward from a conventional aircraft. This makes corners look great. The rates that I backed off out of caution was not necessary. Time to rest these to the factory settings and give some 3D moves a test.
I am impressed with the ability of the Drake to allow a regular pilot like myself to perform 3D maneuvers. The power of the KingTech 210 will hover the Drake but is not enough to pull out of the hover. I need to leave 50 feet of vertical to recover from a hover to be safe. The Rhino 200 SE Turbine Engine is lighter than the KingTech engine and should have more power for recovery.
The hover has some wing rock that I think is due to the aileron gain being too high. The flat spins and high alpha work well. Lazy tight loops are great. Flips are good but could be tighter after I adjustment to my turbine to spool up a bit faster. I cannot get this jet to tip stall. The landings are much better when slowing the jet down for the final turn and pulling the elevator. Moving the rudders towards each other like the manual suggests acts like air brakes and the nose pitches up nicely to help slow down for landings. I am very happy with this jet!