Grosse UHU (oz14159)

About this Plan

Grosse UHU. Radio control glider model. Wingspan 1530 mm.

Direct submission to Outerzone.

Note supplement instructions file includes 34 detailed build pics.

Quote: "Building instructions
Der grosse UHU
1530 mm
Order No. 4545

Recommended radio control systems GRAUPNER/JR FM 414 35 MHz module system or me-10 35 MHz computer system or better; see main GRAUPNER catalogue.

Foreword 'Der grosse UHU' is the ideal first radio-controlled model aircraft. It is the perfect choice for group instruction on modelling courses. The model has been developed with simple, straightforward construction as top priority. Der grosse UHU is not designed for aerobatics. Der grosse UHU responds very well to thermals, and can safely be circled very tightly. These characteristics make it possible to exploit small 'thermal bubbles' to the full.

If Der grosse UHU climbs dangerously high in a powerful thermal, it is possible to lose height safely by placing it in a tight spiral dive. This is done by carefully applying rudder and up-elevator. Note that the elevator setting controls the steepness of the spiral dive.

All components should be checked for fit and trimmed where necessary. Separate the parts into groups corresponding to fuselage, wings, tailplane etc., using the part numbers as a guide.

To build the model you will need a flat, perfectly straight softwood building board of adequate size, eg the system building board, Order No. 645, or the balsa jig board, Order No. 503.

You can deviate from the recommended sequence of assembly if you know what you are doing; this is left up to your discretion.

Refer constantly to the instructions and the parts list while you are constructing the model.

The fuselage: Clean up the spine (1) of the fuselage nose pod with abrasive paper before gluing the side panel (2) to it. The first stage is to glue the right-hand pod side (2) to the spine (1), keeping all the edges flush.

Hold the parts together with modelling pins until the glue has set hard. Remove the pins, and continue the 5 mm 0 hole in the spine through the right-hand side. The hole accepts the wing retainer dowel (9).

Trim the right-hand in-fill piece (3) to fit and glue it in place. To provide freedom of movement of the pushrods (20) when they are installed, you will need to extend the channels in the front end of the fuselage tail boom (4) using a saw and a knife, as shown in the sketch on the plan. The two bowden cable outer sleeves (5) can now be glued in the channels in the tail boom. Glue the sleeve in the top channel followed by the balsa sealing strip (7). Important: ensure that the upper sleeve projects from the end of the tail boom by about 24 mm at the front, and the bottom sleeve by about 60 mm. The sealing strip (7) should end around 170 mm from the end of the tail boom. Allow the glue to set hard, then sand back the sealing strip (7) flush with the tail boom.

The prepared tail boom can now be glued into the nose pod. Check that it rests squarely on the right-hand in-fill piece, otherwise the finished fuselage will not be straight. Trim the left-hand in-fill piece (3) to fit snugly, and glue it to the nose pod, followed by the left-hand side panel (6).

When the glue has set hard, sand the nose pod to the profile shown in section D-D. The next step is to install the wing saddle, but first you must continue the hole for the wing retainer dowel through the left-hand fuselage side. For technical reasons the nose pod cannot be machined to a sharp edge at the wing saddle position, so file the wing saddle (8) at an angle as shown in the sketch to allow for this. Important: When gluing the wing saddle to the nose pod (1) it is important to ensure that the saddle (8) rests squarely on the joint surface. This is very important, as it defines the angle of incidence of the wing (longitudinal dihedral).

Attach the rudder to the fin, and the elevator to the tailplane, using the plastic hinges provided. Glue the hinges in place as shown on the plan, using UHU hart as adhesive; alternatively thick cyano can be used.

It is important to maintain a gap about 1 mm wide between the fixed panel and the control surface. Sand the fin and tailplane to the profiles shown in sections B-B and C-C on the plan. Drill a 3 mm 0 hole in the rudder for the horn, in the position shown on the plan, and a 4 mm 0 hole in the elevator.

Installing the tailplane and fin: Glue the spruce locating strip (14) centrally to the underside of the tailplane. Check with a setsquare that the rear edge of the tailplane is at right-angles to the locating strip.

Glue the tailplane to the tail boom, noting the dimensions stated in the fuselage side elevation. Allow the glue to set hard, then glue the fin in the channel in the tail boom.

When the glue has cured, the horns can be glued permanently in the control surfaces. Cut down the lug of the horn (12) to match the thickness of the rudder.

Installing the servos and receiving system components: Screw the towhook (49) into the nose pod in the position stated on the plan, and secure it with a little glue. The top edge of the machined openings for the servos must be relieved slightly to provide clearance for the servo output arms; cut the wood back at an angle as shown on the plan. Slip the steel pushrods (20) into the bowden cable outer sleeves from the front. Form a Z-bend in the front end of the pushrods using Z-bend pliers (Order No. 5732), and connect them to the servo output arms (21) as shown on the plan..."

Supplementary file notes

Instructions (de, en, fr).

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