Thanks to Ian Mason (http://willowracing.blogspot.com) and Zhou (RGMCN) for this new model. It is always a pleasure to bring them to life.
Getting a Harrier, the new model from Ian/Zhou, was an obvious choice after having so much fun with my E-Willow Sor last year.
As with my other models, I do not compete (yet).
So I make “portable” f3f model. I electrify to be able to fly it more easily everywhere when I take holidays to leave Paris and go in the Alps or by the seaside. The purpose of the motor is not to make a hotliner.
I followed recommendations from Ian on servos and his build notes. It is pretty similar to previous models provided by Zhou and Ian like the willow sor.
- Kingmax servos
- Clevis and horn install under the skin – seamless
- 3d printed w/ bearing servo frame
- Brushless direct drive sunnysky x2220-iii 980kv
- 3s Lipo 2200 mah
- 12×6 propeller
This motor configuration was already tested. My E-Willow has the same and the climb rate is good. The ammeter gets 29Amp at 12.1V – 350 Watts. The Harrier fully loaded is 2.7 Kg… 130 real Watts per Kg.
As a reference, an acceptable climb rate of a sailplane is commonly reached at 100 W/Kg.
Following Ian’s advice (build notes), I asked Zhou to omit the horn from the aileron/flap. I decided to complete a seamless installation without any commercial LDS/IDS system.
Glue the carbon horn to the wing. You can add a small rod in one of the holes, it will lay flat on the bottom of the surface. This allows two things: to set it exactly at the right position and to reinforce the bonding with the expoxy.
Ensure to have the good travel. To keep a nice servo precision, it needs to cover at least 70% of its range to move the surface around recommended settings from Ian.
For my setup, I got on 5mm of horizontal travel for the aileron and 11mm travel for the flap (nearly reaching 80 degrees angle fully open and a small upper movement).
The same movement amplitude is needed on the servo and you can easily replicate when preparing the servo arm and trimmed clevis.
When looking for lower travel, more stiffness is needed to reach a slope free assembly:
use metal, fill micro gaps between arm hole and clevis with cyano (use super glue accelerator and break the fresh bonding manually), cyano the clevis and the threaded rod.
Servo frames are on my Github (fully parametric) and ready to print.
Fuselage – Electric
I got a non-electric fuselage which I cutted to 31mm diameter section.
As with my other fuselage, with the extra weight of the brushless motor + a bit more lead, I reinforced with carbon. The full fiberglass fuselage part (under the canopy) received 3 carbon cloth strips going from wing root to the nose. I use redundant frsky 2.4Ghz + r9 900MHz receivers, carbon is not a problem.
I like redundancy … my classic setup:
– redundant BEC (one from the ESC, one with a 7.2V UBEC put in front of the wing joiner here)
– dual schottky diode creating the power redundancy – It allows also the HV servo to work at 7 Volts.
– redundant receiver (FRsky G-RX8 – 2.4Ghz + FRsky R9Mini 900MHz)
– telemetry for the battery level from the g-rx8 receiver A2 connector.
G-RX8 is also providing the telemetry VAlt+/- and VSpeed.
More info in another post here
Follow he settings provided by Ian Mason (http://willowracing.blogspot.com/p/harrier-build-notes.html).
I am reaching a CG of 99.6mm from leading-edge with a very acceptable lead cylinder of 100 grammes (added behind the motor firewall).
Final e-harrier ready to flight: 2.7Kg.