Grob G109 Scale Glider Review

Brenton Wildman

I was in Modelflight looking for a new project, one that would get me into the air on those not so calm Sunday mornings that I did not want to risk my large-scale electric planes. It had to be electric and an ARF that would be cheap and quick to build. The Grob-109G by ESM caught my eye as a scale model and further gathered my interest when I read it was electric! The model was also of a decent size having a large one piece flat bottomed wing of 2m (which is not a problem for transport in my vehicle but may be for some).

Upon opening the box, everything was found in sealed plastic bags neatly stuck down to minimise transport-induced damage. The wings are foam core covered in balsa and a pro-film type white covering (be careful – they do mark easily). The ailerons are pre-cut and fitted with mylar hinges that only need to be glued. The main fuselage is made of gel coated fibreglass which was extremely light to pick up. All the push rods were preinstalled and only require connectors to be screwed in. The kit even comes with the motor and folding prop preinstalled! The only extras needed are 3 standard servo's, a 20-35Amp-speed controller, 4-channel receiver and a battery pack.

In following the instructions, I glued the Ailerons on and pinned them using cut down metal pins. The outermost hinge receiving 2 per side. In my rush I did not cut out enough of the first rib to fit the aileron Servo (the picture and diagram are different – so test fit a servo!) and was extremely difficult trying to fit the servo so that the control rods were at right angles as required. Apart from that, the fibreglass wing joiner was a firm fit and within 30 minutes I had the wings joined.

In letting the wing fully set, I jumped over and fitted the tail and rudder. The tail plane was a tight fit screwing into preinstalled metal inserts. What did need a little clean up was the rudderpost as it was not flat and required sanding and then cuts for the mylar hinges. If you can, use a steel ruler to ensure the cuts are all in a perfect line else there will be a resistance when moving the rudder. The rudder was then glued and pinned.

Two servo's were installed into the fuselage body into the preinstalled tray (I’m beginning to like all this pre installed stuff) and linkages for rudder and elevators were then installed with no major difficulty. I found that the control snakes need a little bracing in the fuselage near the servo's to provide smooth movement. With the wing set overnight, the Aileron servo tray was installed and glued. I found it necessary to dig out the control rod in the wing to stop some binding on one side wing.

I used epoxy to glue in some velcro for the receiver and Speed controller. I find this better than double sided tape to allow for easier removal in servicing. I removed the motor for inspection (or maybe it was curiosity). It is about a 540-600 in size and weight. I fitted suppression capacitors to the motor and left it to run in using a single C size cell. This allows the brushes to wear down to a nice fit before being subjected to high currents.

To get the correct C of G, I installed a 7 cell 3000NiMh pack I use for my other planes. I use a combination of velcro tie downs and foam blocks to hold the packs tight. A quick test of the motor and Esc showed 26A at 7.4volts giving 11300 rpm.

After final testing it was time to take it to the club field for a once over by the Instructors and other members at Noarlunga Model Aero Sports. I find this a good way to make sure you haven’t forgotten something or not adhered to best practice procedures. From this, modifications that I saw was needed was a tail skid to stop the rudder hitting the ground on landing and applying tape to the ailerons to avoid any flutter. Those ailerons run the whole length of the wing and roll the plane with great authority.

Overall this is an impressive electric plane that does attract other flyers to take a look and discuss. It only took 1 week from purchase to completion – Flying took longer due to the weather being absolutely wet on the weekends. I cannot wait for summer so that I can test it out on some thermals and sit back and relax in the warm sun.

"Hang in there Brenton, summer is just
around the corner!"

	ESM Grob G-109 - 2 metre ARF scale glider, fibreglass fuselage, foam/balsa wings. Aileron, rudder, elevator control. Speed 600 or .15 powered. View ESM Grob Review