Building Scale Model Helicopters

New Series!
New Series!
Building The Graupner/Heim BO 105
By Jeff Barrington - Mid Devon Heli Club

Graupner/Heim  BO 105 - Parts of Kit The full sized BO 105 is a twin turbine engined helicopter made in Germany and is commonly used for police and air ambulance in the UK, so there are plenty of examples to choose from for the scale model. The purpose of this article is not to go into every detail but more to point out the areas not very well covered in the manual.

The BO 105 kit is the latest from Graupner/Heim and is for use with the Uni-star or Uni-expert mechanics and is good value at £220. I will be using the Uni-star, which I have had for some time and have used in an Agusta 109, a Sea King, and in pod & boom form. It is always best to use mechanics, which have been flown and fully tested, as accessibility is more of a problem once fitted in the fuselage.

Graupner/Heim  BO 105 -  FormersThe fuselage is made of epoxy glass and is in 3 sections, the main section, the top section and the rear part of the vertical fin. The general finish is very good and all the window holes are pre-cut. Also in the kit is the wood pack, which again is pre-cut and of good quality ply, ABS mouldings from which the horizontal fins are cut and joined, a pre-cut window set, tail drive shaft, carbon rod and bellcrank for rudder control, and an instruction manual in German! The 40-degree gearbox for the tail drive is not included in the kit but is available from Graupner/Heim at around £45.

Graupner/Heim  BO 105 - U/C MountingBuilding starts by drilling the skids and fitting them to the cross sections with self-tappers. One skid is then removed to slide the undercarriage into the fuselage through the pre-cut holes. The ply formers are fitted with captive nuts and lined up inside the fuselage with plastic brackets holding the undercarriage to the formers. Some fiddling is now needed to get the model sitting level on its undercarriage before permanent fitting of the formers to the fuselage with epoxy resin. I had to sand the edge of the formers a little to achieve this.Graupner/Heim  BO 105 - Lower Formers

The remaining ply plate and lower formers are temporarily bolted to the mechanics and placed into the fuselage along with the upper mounting plate. A lot of measuring and lining up is now required before permanently fixing the upper and lower formers to the fuselage with 1 hour epoxy. I spent some time getting everything lined up nicely as once fitted its to late. When the epoxy has hardened the mechanics can easily be removed by unscrewing the six mounting bolts.

In the next part I will be fitting the tail drive and rudder control.

This page has been contributed by Jeff Barrington
Web Site: Mid Devon Heli Club