The BELL-47G from Graupner is one of the first commercially produced and available RC helicopters with cyclic blade adjustment. The first versions were available from ~1975.

Description from the Graupner catalogue text of that time:

An interesting model with lines just as impressive as the original, which has proven itself worldwide as a universal helicopter. The original is used for surveying flights, research work, construction transport in mountainous and inaccessible terrain, for checking and repairing high-voltage lines and pipelines, for traffic monitoring, for search and rescue operations and wherever particularly difficult tasks have to be mastered.

The model corresponds to the original in all essential points. The fuselage structure in the plug-in system significantly shortens the construction time of the ready-to-fly model.

The injection-molded parts are made of high-quality plastic. The brackets for the RC installation are already present in the fuselage.

In addition to the RC-system, the quick-build kit contains all the parts for the ready-to-fly model including mechanics, tank and motor, even accessories for the RC-installation such as Bowden cables, etc.

The large, crystal-clear full-view cockpit and the side tank dummies give the model its characteristic appearance. However, the helicopter can also be flown without this equipment. The mechanics are manufactured with the well-known HB precision. The combination of fully assembled units makes the structure very clear. The main rotor shaft is made from solid material and is heavily dimensioned. The tail drive shaft is guided in a straight line. All adjustment work is limited to setting the blade tracking with just a single screw. Wheels, headlights, position lights and pilot dummy are not included in the kit. The design can be done at your own discretion.

Article overview:

Order number 4601

Quick-build kit with prefabricated components airframe, mechanics, drive, including engine

Order number 4601/79

Extension kit full-view cockpit and tank dummies

Order number 4601/78

Chassis kit SEA

Order number 4601/80

Chassis kit Training

The BELL-47G model was first presented at the 1975 Nuremberg Toy Fair and then launched onto the market a few months later. The model was innovative for the time: the front and rear assemblies were made of injection-molded parts that were otherwise known from Revell or Super-Airfix kits. Many details could be easily reproduced, the construction was comparatively simple and the manufacturing process used gave the model a very good scale appearance.

The injection-molded parts of the front and rear assemblies could be put together using tabs and connected using small plastic wedges and plastic glue. The tail boom in the typical Bell tubular construction was attached to the front assembly with four screws for maintenance and easy replacement.

The HB-25H engine was specially developed by HB for the model and had both a cooling fan mounted on the flywheel and a large rectangular ribbed cylinder head for additional cooling. This type of cylinder head became synonymous with future engine versions that were used in model helicopters.

In addition to the unusual construction method of the fuselage components, the model had a number of other unusual features. These include the control paddles, which were also made as complete injection-molded parts instead of a steel rod with a paddle attached to the end. The main rotor blades were mounted by hanging them in a pair of open claws in which the cross pin was hooked into the blade root. The main rotor blades were therefore not screwed to the hub of the rotor head, but were held in position solely by centrifugal force. This design also allowed the rotor blades to flap in horizontal flight. The tail rotor was controlled indirectly by pressing the pitch adjustment lever onto the tail rotor pitch control rod in only one direction of action; the necessary reset was carried out by means of a spiral spring inside the tail rotor gear housing.

The digital restoration of the Graupner BELL-47G was perhaps the most extensive project at CADDICTED to date.

The first models were purchased second-hand in around 2005, with the aim of actually restoring them. The models delivered were in a desolate condition. Poorly assembled, certainly never flown and the metal parts were very badly corroded. For professional and private reasons, the parts then disappeared into a box marked 'Later'.

In 2022, original kits in individual parts were suddenly available via a well-known auction platform. Condition virtually 'New Out of the Box'. Original condition from early 1976. That gave me the idea to digitally restore this unfulfilled childhood dream of mine. Back then, around 1978, a purchase was simply beyond the realm of possibility for a 13-year-old. At the end of 2022, a large part of the individual parts were measured and transferred to CAD. The model was then digitally created in every detail according to the construction stage instructions.

The targeted work on the model was then interrupted by the complete digital restoration of the associated HB-25H engine, the short-term prioritization of other projects (Graupner GO-KART-10-GP) and the fact that the modeling of the full-view cockpit, along with the paintwork and adhesive images, was actually not trivial in CAD modeling. Up to that point, I didn't know much about surface modeling.

At the end of 2024, things looked much better. With new enthusiasm, time and CAD know-how, the remaining work steps were completed. All parts were given the appropriate material and part parameters in CAD and I was able to create the parts lists. The layout and contents of the blueprints were redefined in the CADDICTED style. It was clear to me that it would not remain on one page, there was too much to show.

Now, at the end of February 2025, the final results are available. There are a total of five blueprints, a lot of CAD- images in different views, which I hope will be enjoyable to look at.

It is interesting that now, in spring 2025, it will be exactly 50 years since the model was introduced as a novelty at the Nuremberg Toy Fair in 1975. I just hope that I can make some model building enthusiasts happy on this special anniversary and that the images will take us back to that time and enthusiasm.