Agusta-Bell 206B RC Helicopter in Scale 1:5.7 of the Greek Army Aviation




Introduction

I have started this blog as an english-text alternative to a thread that I have opened in modelclub.gr (modelclub forum in greek) regarding my project to build an RC scale model of an Agusta-Bell 206B Jet Ranger II of the Hellenic Army (see unofficial site).


Now a few words about the project itself. The model is based on the fuselage provided by Vario (model 1004) in scale 1:5.7. There are very little differences between a Jet Ranger III (model kit) and an Agusta-Bell AB-206B Jet Ranger II that I needed for the project, so I decided to get the kit from Vario. The kit has been bought from one of the best specialists and professionals in the field, Mr Thomas Baumann who has helped me with making my choice of the model and its accessories (Helikopter Baumann). Thanks Thomas! I would also like to thank the team of eflight for their professional support not only for this construction but for all my RC models and accessories. In addition, I would like to thank the team from Innoflyer and especially Mr. Christophe Raible for the help with the lighting system and for letting me test a new CPL model before its official launch. I would like to add here the biwix.com RC helicopter store and Johnny Trolliet at my hometown Renens for his exceptional service, availability and prices!

The particularity of this project is that the mechanism that I fit in the fuselage is not the one from Vario but a modified Align T-Rex 700E (Align RC Helicopters). I will give here details on the way that this is done with diagrams, photos, tips and tricks. This will cover the first part. The flight tests of the modified T-REX 700E have been conducted at the RC model field in Dizy, Switzerland that belongs to the Dizy RC Modelling Group (GAM Dizy). Big THANKS to all the members of the Club for the great friendliness since the first day I started there and for their help with advice and tips!

The second part will be dedicated to the scale model itself. Some photos of the Greek AB-206B can be found on the internet but they do not cover all the details. More photos of the aircraft with the Greek colors may be requested in the forum of modelclub.gr where I have gotten most of them thanks to the team spirit and great friendliness of the members (THANKS^1000 dsamba!!!). In order to complete the photographic part of the project I managed to get my own photos of a Jet Ranger III. This has been made possible thanks to the courtesy of the people from Heli-Lausanne (Heli-Lausanne) who have immediately accepted my request to get there and take as many photos as I needed. A big THANKS to them too!!!
At the last phase of construction, I have got invaluable help for the dimensions of the AB-206B landing gear from Iraklis Karailidis. Many-many thanks to you Iraklis!

So after this short introduction I will start publishing the steps I have already taken and will take during this quite challenging project (at least for me, it is my first scale RC helicopter).

I hope that you will find this blog helpful if you have a similar (or the same) project as mine and you will enjoy it as much as I do!

Welcome!
Hellenicopter

27/04/2014

New video with one of the latest "real" flights (not only hover) of my Jet Ranger.



I have a lot of practice to do and adjustments of my V-Stabi to make as it is still set for quasi-3D flight and not for a scale one.


Enjoy the new video. I hope to have more on the construction the coming days.

Cheers!

14/04/2014

Small update on the mechanics.

After some adventures with the main shaft some changes have been made to the mechanics. I will soon update the pdf but first I present them here.

Before all, a big THANK YOU to Nicolas Jaunin for helping me with the fabrication of a new shaft. The old one had a flaw or got a hit without noticing it and the helicopter was vibrating like crazy.

With the new shaft there are practically no vibrations (other than the "normal" ones that every helicopter has). Nevertheless, I have decided to lower the headspeed from 1450rpm down to 1300rpm. For that the easiest way was to remove 2 cells from the battery pack and use a 10S pack instead of a 12S (saved ~200g too! - 5.4Ah ThunderPower pack). In that case there are less stresses on the rotor head but I needed to modify the gear ratio for the tail rotor as well as the tail rotor blade size because the tail rotor lost quite a lot of its efficiency.

Fortunately, Align has what is needed for that thanks to its T-Rex 800E model parts. So I have replaced the tail gear set and the blades with the following pieces:

HQ1150B (115 Carbon Fiber Tail Blade, T-Rex 800)
H70110 (T-Rex 700E 104T M1 Helical Autorot. Tail Drive Gear Set)
H70111 (T-Rex 700E Motor gear mount)

The latter (motor gear mount) is very important to change as the big white gear is bigger than the previous one and if you keep the old mount it will not fit (it is well mentioned on Align's web site too).

So now the headspeed is really optimal and the tail rotor does it's job very well. The gyro gain is around 70%. It comes to my mind now that I have not published yet the settings of my V-Stabi as well as those of my Hitec Aurora-9. A big help for fine-tuning the headspeed and the pitch curve was the J-Log2. The data recording feature from the Kontronik Jive 80+ HV ESC and, most of all, the possibility to send that data to the Aurora-9 via telemetry have been most useful for the finetuning. I will post some plots this week to show the power consumption and the current flow through the Jive.

Cheers,
Hellenicopter.