Gemini (oz12969)


Gemini (oz12969) from Keil Kraft 1963 - plan thumbnail

About this Plan

Gemini. Simple rubber sport model. Wingspan 21-1/2 in.

Note the fuselage is not shown in detail on this plan. The kit included fuselage parts die-cut and ready to assemble - see steps 1 to 7 of the instructions on the plan sheet. This is the complete plan, as supplied in the kit.

Planfile includes full build instructions.

Quote: "All the sheet balsa parts for this model are die-cut to shape. Simply press them out carefully, when they are ready for assembly.

Follow the step-by-step stages 1,2, 3,4, etc, using balsa cement for making all glued joints. Where necessary, hold parts together with pins until set. The wing is built directly over the full size plan. Cover this part of the plan with a piece of thin polythene to prevent parts sticking to the paper.

1. Carefully press the parts from the die-cut panels. Brace formers 2 and 3 with 1/4 x 1/8 balsa as shown above.

2. Cement the undercarriage wire to former 2, then cement piece 5 to the former and piece 6 on top of piece 5 and the wire. Cement well and leave to dry.

3. Cement the right fuselage side to former 2. Once again leave to dry.

4. Cement the other fuselage side in place. Join the rear ends of the sides.

5. Add formers 3 and 4, then cement former 1 between the two sides at the front. (Use an elastic band to hold the sides to the former). Piece 7 should be cemented to the top of the fuselage.

6. Cement pieces T1 and B1 in place, then add the rest of the top and bottom sheeting (pieces T2 - T3 and B2 - B6). Cement a rolled-up empty cement tube inside the fuselage immediately behind former 1. Cement the shaped piece of block to the top of the nose and sandpaper to fit the sides. Cement the cabin celluloid in place, and when dry, cement a piece of 1/8 dowel through the celluloid on the underside of piece 7 (to hold wing fixing elastic bands).

7. Cut the nose block to the full size pattern given, cement to the front of the model and sandpaper to fit the nose of the plane. Put the plastic nose-plug in position and sandpaper the block to 'fair-in' with it.

8. Cement a fin to each end of the tailplane, support the tailplane on a block and leave to set, taking care that the fins are upright. Rub the wing plan with a piece of soap to prevent parts from sticking to it.

9. Cut a piece of triangular trailing edge to size and shape, cut notches at the rib positions, then pin in position on the plan. Cut a piece of 1/4 x 1/8 balsa 10-1/2 inches long, cut the end to the shape shown and pin in place together with a piece of the shaped leading edge.

10. Cement the ribs in place, taking care that they are all upright. Add the front and rear braces and small gussets at the tip. (Note: no pins are shown on this or subsequent drawings to avoid confusion. Use them as required).

11. Build the other half wing in the same manner as the first. When the braces are added, support the left hand wing panel so that the tip rib is 3-1/4 in above the plan.

12. Lay the wing so that it rests on the centre section and pin in place on the plan. Cut pieces of leading and trailing edge to fit and cement in place followed by the two sets of half ribs. (Upper sketch.) Cement the centre section sheeting in position. Check that each tip rib is 1-1/2 in above the plan and leave to set.

13. Cement piece of 1/2 x 3/8 balsa to the outside of the tip rib, it should fit neatly between the leading and trailing edges and lay flush with the bottom of the rib (A). Carve and sandpaper the block to the shape of the rib (B). Now carve the block to the shape shown on the plan, rounding the leading and trailing edges as well (C). Finally sandpaper the tip to a smooth round section and taper the back of the trailing edge to a sharp edge (D).

COVERING: Cover the wing with the tissue provided, using tissue paste as adhesive. The bottom should be covered first. Cut a piece of tissue a little larger than one wing panel plus the centre section. Apply paste to the bottom of one of the centre ribs, the leading and trailing edges of the centre section and wing panel and the bottom of the tip. Lay the tissue in place, smoothing it on to the pasted rib. Stretch gently and attach to the tip. Now work from the the tip gently easing the tissue outwards. When evenly in place, trim off the surplus.

Cover the remainder of the bottom of the wing in a similar manner. The upper surfaces of the wings are covered in the same way, using one piece of tissue for each wing and a small piece for the top of the centre section. When the paste has dried, apply two coats of slightly thinned down clear dope, allowing to dry out between coats. This will tighten and toughen the tissue.

ASSEMBLY: Hook the two rubber bands on to the propeller hook and tie a piece of thread to the other ends of the bands. Drop the end of the thread through the hole in the nose block and shake it down through the fuselage until it can be led out through the hole in the bottom, just forward of the tailplane position. (It will shake through the fuselage easier if a small weight is tied to the end of the thread.)

Pull the rubber bands through the fuselage and pass a piece of 1/8 dowel through the two small holes in the fuselage sides, passing through the rubber bands in between.

Pass two elastic bands over the rear of the fuselage, hold the wing in position and pull the bands over the wing and hook them on to the wing fixing peg. Pass another band over the rear of the fuselage, hold the tailplane in place and pull the band over the tail and hook it over the rear of the fuselage. The model is now complete.

FLYING: When supported by the finger tips under the wing spar, the model should balance approximately level. Check that the wing and tailplane are on squarely.

Choose a day that is not too windy for test flying. Launch the model firmly, but not too fast directly into the wind on a slightly downward path. A long flat glide should result (see diagram).

Should the model STALL, place a little packing under the FRONT edge of the tailplane. Should a DIVE result, a little packing under the REAR edge of the tailplane will cure it. Make any adjustments necessary a little at a time.

When the glide is satisfactory, powered flights may be attempted. If you find that the model 'over-climbs' on full power and seems to 'hang on the prop' (power stall) place a little packing between the TOP edge of the plastic nose plug and the nose block.

To make the model turn, slew the tailplane round a little - but take care not to overdo it.

The 'GEMINI' is a robust model and should give you many hours of flying - so take your time over building it and you will be more than satisfied with the result. "

Direct submission to Outerzone.

Update 20/04/2021: Added fuselage formers, thanks to AdrianCulf.

Supplementary file notes

Fuselage formers.
Fuselage sides.
Tail parts, plus cabin glazing.
Wing parts.


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Gemini (oz12969) from Keil Kraft 1963 - model pic

  • (oz12969)
    from Keil Kraft
    21in span
    Rubber F/F
    all formers complete :)
  • Submitted: 02/04/2021
    Filesize: 485KB
    Format: • PDFbitmap
    Credit*: AdrianCulf

Gemini (oz12969) from Keil Kraft 1963 - pic 003.jpg
Gemini (oz12969) from Keil Kraft 1963 - pic 004.jpg

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Download File(s):
  • Gemini (oz12969)
  • Plan File Filesize: 485KB Filename: Gemini_oz12969.pdf
  • Supplement Filesize: 1103KB Filename: Gemini_oz12969_fuse_formers.pdf
  • Supplement Filesize: 832KB Filename: Gemini_oz12969_fuse_sides.pdf
  • Supplement Filesize: 1085KB Filename: Gemini_oz12969_tail_cabin_glazing.pdf
  • Supplement Filesize: 778KB Filename: Gemini_oz12969_wing_parts.pdf
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* Credit field

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