GLA (oz11007)

About this Plan

Bridi GLA (Great Little Airplane). Radio control 4 channel basic trainer. Shoulder wing layout. Wingspan 59-1/4 in, wing area 625 sq in, for .25 to .45 engines.

Later kitted by Bridi Hobby Enterprises.

Quote: "This four-channel trainer is truly a 'Great Little Airplane'. Follow the step-by-step instructions and you can't go wrong.

Designed by Joe Bridi. Text and photos by Al Tuttle.

Construction of the 'Great Little Airplane' is straightforward and requires no exotic or odd-size materials. All hardware is readily available from your hobby dealer. The canopy, dural landing gear, and motor mount are available from Bridi Hobby Enterprises, 1611 E Sandison St, Wilmington, CA 90744.

Because this aircraft is aimed at the newcomer to radio control, the instructions may seem to be oversimplified to you old-timers - remember, we were all neophytes once. For example, you will notice that I keep harping about minimum or no gap at the control surfaces. Though a seemingly insignificant point, much of how well or how badly the aircraft performs is due to this little detail. How many newcomers (and 'experts' too) have you seen at the field who wonder why their aircraft response in the air is so sloppy, only to find a gap of 1/16 or more at the control surfaces? If the instructions are carefully followed, you should end up with a straight, strong, and excellent flying basic trainer.

For adhesives to use, I'd recommend 5-minute and 30-minute epoxies, Hobbypoxy Formula 2 epoxy, Wilhold or Franklin aliphatic resin (Titebond), Hot Stuff, ZAP or its equivalent, and Duco cement or its equivalent for attaching the canopy, although the cyanoacrylate adhesives (Hot Stuff, etc.) can also be used.

To make sure all parts - such as leading and trailing edges, empennage, and control surfaces - get sanded evenly and straight, make up a couple of sanding blocks to be approximately 12 to 18 in long and 2 to 3 in wide. I use 1/2 x 3 in wide aluminum channel stock with the sandpaper attached to the block with double-sided tape. This makes it easy to replace the worn-out sandpaper. The building sequence is as follows: wing and ailerons, empennage, fuselage and hatch, final-sanding and covering, and equipment installation.

Read each step completely and carefully!

WING CONSTRUCTION: Pre-construction:
1. Cut 22 ribs from 3/32 sheet balsa stock.
2 Make four trailing edge pieces 7/8 wide from 3/32 sheet balsa and cut to length.
3 Cut to length: four 1/4 x 3/8 balsa spars, two 3/8 x 3/4 balsa leading edges, and two 3/16 x 1/4 trailing edges.
4. Cut two ailerons 1-1/16 wide from 1/4 sheet balsa. Do not trim to length or round edges yet. Note: If stick stock is not available, the spars and trailing edges can be stripped from 1/4 sheet stock..."

Update 10/1/2024: Added kit review from MAN November 1982, thanks to RFJ.

Quote: "Field & Bench Review: GLA from Great Planes, by Jim Kitchen.

DURING THE SUMMER of 1980 evil R/C spirits caused me to lose two different models. First there was my .40-powered Wing Drone that folded its foam wing in flight during a fun-fly competition. Then there was my .20-powered Bridi Sportster that crashed while making a low level, inverted flyby - pilot error, I'm afraid.

The loss of these airplanes left me with no aileron-equipped models, and provided the impetus to go back to the building board and remedy the situation. I like to have a .40-powered sport model to use for fun-flys, and for keeping up my acrobatic proficiency. They're also good for breaking in new engines, and testing new and repaired RIC systems.

Besides ailerons, I also wanted simple construction, a high wing, a semi or symmetrical airfoil, an uncowled engine, and tricycle landing gear. These features are all present in the Great Planes GLA Basic Trainer, making it an ideal choice for a .40-sized trainer/sport model. Size is another plus. A 59'41 inch wingspan, 625 square inches of wing area, and a 47-inch fuselage make it one of the largest models in its class.

Prior experience with three other Great Planes (formerly Bridi) kits decided me to build this new one. I've built the Basic Trainer (MAN, October 1974), Super Kaos 40, and Sportster, and I expected the same kit quality in terms of materials, parts, building instructions, and plans. I was not disappointed.

THE KIT: The first thing that impressed me was the small and colorful box. Most comparable models would have been in a box at least half again as big. This smaller box is handy for us kit hoarders, who have a problem with storage. The box top has a three-color photo of an actual model which can be used as a suggested finishing scheme.

I was also impressed with the neat way all the kit parts fit in the box. The aluminum dural landing gear and wire nose gear were wrapped in tissue paper to prevent them from scratching and denting the balsa components during shipment - a nice detail.

As a civil engineer, I can appreciate the GLA's detailed, full-size plans. They are understandable, with all parts labeled and a number of construction details shown. An experienced modeler can build the model using only the plans, but the assembly instructions and a separate set of assembly photos will be valuable to the novice. Twenty-five pages of assembly instructions indicate careful thought has gone into explaining the little things veteran modelers take for granted.

The instructions will not only explain what is being done, but why it is done, with some tips on improving the end result. A novice builder will pick up useful ideas that should become part of his building techniques.

The assembly instructions suggest three different kinds of adhesives: aliphatic resin, 5-minute epoxy, and cyanoacrylate instant glue.

The parts and balsa stock are well suited for their intended purposes. The factory-sawed parts, such as wing ribs, fuselage sides, rudder/fin, and stabilizer/elevator are a welcome relief from the die-cut parts found in many kits.

CONSTRUCTION: Because the plans and assembly instructions are so thorough, there is nothing I can add about construction details. I will comment on the features I especially liked, provide reminders about things to look for, and offer a couple hints.

The use of 3/32 balsa for wing ribs, sheeting, and cap strips results in sturdy construction. D-tube wing construction includes shear webbing for the entire wing length and enchances wing strength. By cutting all the 1/16 balsa shear webbing before starting wing assembly, you can use the webbing as spacers while gluing ribs to the bottom spar. This insures a good fit for the shear webs, and makes the wing ribs perpendicular to the spars.

Building a straight, true wing is important to the model's flying performance. I use a 1 inch by 12 inch by 4 foot piece of pine shelving, specially selected for straightness, as a wing building board. I end up with sore thumbs from pushing T-pins into the pine, but I feel the extra effort is worth achieving a straight wing.

The GLA wing has a semi-symmetrical airfoil, and is constructed as two panels. A piece of bevelled balsa is provided as a center rib, which will insure the proper 1-1/4-inch wing dihedral. There is no plywood dihedral bracing, so the fiberglassing of the dihedral joint is a necessary strengthening step. This fiberglassing also provides a hardened surface to prevent the wing saddle and rubber bands from gouging the wing.

Long tail moments are a characteristic of Great Planes designs. A scarf joint is used to glue the two fuselage side pieces together, and 1/16 plywood doublers extend from the firewall to the end of the radio compartment at Former 3 to form a rigid box. This will include both the fuel and radio compartments. These doublers also provide additional reinforcement to the scarf joint..."

Supplementary file notes

Article.
Review.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction