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SIG King Kobra, Building And Flying Instructions, Page: 31 / 31

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SIG King Kobra Building And Flying Instructions Download Page 31

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RECOMMENDED CONTROL SURFACE MOVEMENTS

ELEVATOR

9/16" UP and 9/16" DOWN

RUDDER

1-5/8" RIGHT and 1-5/8" LEFT

AILERON

1/4" UP and 1/4" DOWN

 
 

FLYING

 
IMPORTANT: The King Kobra is not a model for low-flying time pilots. If you have 
little or no previous RC flying experience you cannot successfully fly a fast and 
responsive design like the King Kobra, particularly on test flights. It is suggested 
that you not attempt flying without the assistance of a modeler with experience. 
Contact your local model club or ask your hobby dealer for the names of good 
fliers in your vicinity and a suitable location for flying. 
 
Many hours of work are involved in the construction of a model and it can all be 
lost in a moment of beginner's indecision. Even if you have some experience, an 
expert flier can help you get past the first critical test and trimming flights without 
damage to the model and give instruction in proper control.

 

NOTES ON LOOPS

A true wing will perform perfect loops. 
A twisted wing will loop obliquely. One 
wing half being heavier than the other 
may also affect loop tracking. A side 
mounted motor may make one side of 
the model heavier than the other. Put 
weight in the opposite wing tip until 
the model is balanced. Should your 
model snap roll out of the top of a 
loop, it may snap in the direction of 
any twist in the wing, but the real 
reason for it snapping is because of a 
stall. This is probably due to one or 
more of the following: 

Airspeed too low.  

C.G. too far back.  

Pilot pulls too much elevator, a 
mistake aggravated by 
excessive elevator travel which 
makes the elevator more 
sensitive. Reduce travel of 
elevator and use more care in 
transmitter stick movement.  

Not enough power, too high a 
wing loading for the available 
power or both. 

 
Be certain to carefully range check your radio equipment and see how it operates 
with the engine running before attempting test flights. A lot of problems can be 
avoided if the engine has been well broken-in and the idle adjustment perfected 
on a test block or in another airplane before installation in the model.

 
Takeoffs with the King Kobra from grass fields are easily made if the grass is not 
too long or the ground too rough. Generally a lot of elevator application is 
required for liftoff. Be prepared to relax control pressure partially after becoming 
airborne so the c1imbout will not be too steep. On surfaced or smooth dirt 
runways less application of elevator will be needed.

 
After each test flight, readjust the RC clevis links on the push rods so that the trim 
levers on the transmitter can be returned to a neutral position. It will take several 
flights before exact trim is established on all axis of flight.

 
 
 
 
 
 

© Copyright SIG Mfg. Co .,Inc.

 

SIG MFG. CO., INC............Montezuma, Iowa 50171-0520

 

LIMIT OF LIABILITY:

 

In use of our products, Sig Mfg. Co.'s only obligation shall be to replace such quantity of the product proven to be defective. 
User shall determine the suitability of the product for his or her intended use and shall assume all risk and liability in connection 
therewith.

Summary of Contents for King Kobra

Page 1: ...e most builders of this kit will probably have had some experience we were tempted to short cut the instructions This was not done Some skilled fliers may not have had much prior building experience and beginners at both building and flying will probably be constructing the model for future use Other readers with considerable expertise may feel they can skip the instruction book Our advice is the ...

Page 2: ... be made by gluing sandpaper to a flat spruce stick for working tight places A modeling knife or jig saw can be used for cutting out printed parts Don t cut too close to the lines leave some extra wood outside the lines True up and finish the edges with a sanding block as you are fitting the parts together Don t force die cut parts from the sheet Use a modeling knife to finish freeing them ABOUT P...

Page 3: ...line marked A Cut the other 6 sheet piece diagonally in two with the untaped side up in the opposite direction as shown by the dotted line marked B This provides 4 wing skins with the untaped rougher glue seam on the outside surface of the wing The smoother taped side should be used against the foam wing for best adhesion of the skin to the foam The rougher outer glue seams can be sanded down part...

Page 4: ...ngs are skinned Stand the cores on end to dry The cores should be coated first because they take slightly longer to dry than the wing skins d Coat the wing skins with Core Bond e Allow the cores and skins to dry completely This generally takes about one hour In conditions of high humidity it may take somewhat longer It is best to join the parts as soon as they are dry since if they are allowed to ...

Page 5: ...aightness A bow can sometimes be corrected by hand pressure and twisting the assembly before proceeding 18 Rough trim around the edge 19 Repeat Step 14 15 16 and 17 on the other side as steps 19 to 21 22 Trim and sand the edges of the sheeted foam cores While the regular sanding block can be used note how useful an extra long block is for this purpose The one shown is made from a section of alumin...

Page 6: ...he radius of the wire at the bend will fit down into it The gear should fit into the block snugly but not so tightly that it will jam in the block You may want to remove it later for straightening after a hard landing Place a nylon landing gear strap held on by NO 2 screws across the gear at each end to retain the gear in the groove 29 The angle already cut into the ends of the foam wing halves se...

Page 7: ...ube bearing and horn wire Epoxy in place Don t get glue into the bearing NOTE Before the next step is done you will need the fuselage with the rear bottom just behind the wing shaped and the wing mounted in final position 38 a Set the wing into the fuselage and mark a line on the back of the WTB blocks to indicate the fuselage outline b Carve the WTB blocks to shape NOTE Pictures 40 and 41 show th...

Page 8: ...ace against the fuselage sides NOTE We tried the block farther forward on some prototypes so you may see it in a slightly different location in other pictures The way shown here in the corner is strongest 44 a Locate the positions of the wing bolt anchor blocks on the bottom of the wing Remember that the wing bolt holes are drilled at an angle so that the heads of the bolts will end up flush with ...

Page 9: ...ty Coat the entire inside of the cavity with epoxy glue to prevent the foam from being damaged by fuel or dope 51 The plastic servo mount in the photo is fastened to hardwood mounts with No 2 screws Other brands may need a different arrangement 52 a Draw a centerline on the front of the 7 16 x1 1 4 shaped aileron stock and shaping lines on top and bottom as indicated b Carve and sand the front of ...

Page 10: ...ES Using a No 11 X Acto blade or similar cut a slot approximately 1 2 in depth and slightly wider than the hinge After all slots have been cut insert an Easy Hinge halfway into each slot in one of the pieces to be hinged Then carefully slide the matching model part onto the other half of the hinges You ll find it easiest to slide the part onto the hinges at an angle one hinge at a time At this poi...

Page 11: ... tool to clear the pump mounted on the back of the engine Since the firewall is 3 laminations thick this was no big deal there was still plenty of wood left to do the job However other engines may be bulky enough to require more room in the rear We suggest here an easy method of getting more clearance behind the engine by lengthening the cowling Optional Cowl Extension The average 60 will not need...

Page 12: ...osition the nose gear bearing on the face of the firewall and drill out the holes with a 7 64 bit to pass the bolts b Turn the firewall over and drill out the backs of the 7 64 nosegear bearing holes with a 9 64 bit to take the shanks of the 4 40 blind nuts To complete the holes take a modeling knife and round off the edges on the back of the firewall so that the rounded off part of the blind nut ...

Page 13: ... the prototype we saved the sawn out portion of the back of the cowl and glued a piece of it permanently onto the fuselage This filled in the opening behind the engine and gave a more finished look to the installation 67 a Cut the front pieces of 1 2 triangular stock to size and glue on the fuselage sides 68 Note the placement of the triangular stock at the front The bottom stock is placed flush w...

Page 14: ...gap remains at the end of the front bottom triangular stock Cut a small piece of 1 16 balsa sheet thinned down to 1 32 thickness to fit in this gap b Glue it in place 78 Pin the two fuselage sides together outside to outside and match them by sanding as required to make them exact duplicates 79 a Turn the sides upside down on the top view plan b Note that the little end tab on the fuselage needs t...

Page 15: ... place Since it will key the front of the stabilizer make certain that the top of F 6 lines up with the printed edge lines on the fuselage sides 88 Cut FTB from 1 4 x5 8 trailing edge scrap Add FTB just to the rear of F 4 The edges of FTB must be beveled to fit against the triangular stock 89 Complete the bottom planking up to the rear of the wing opening 90 Glue the previously cut triangular stoc...

Page 16: ...ning without trouble Fix anything in the way Hold a piece of sheet on the top to make certain there is no hangup on it This is a good time to oilproof the compartment Put in properly you will seldom have any need to take out the tank and it is not difficult to do so when necessary For the fixed gear version the bottom block is installed in the same way as the following Kougar pictures 98 99 and 10...

Page 17: ...t an angle to fit against the front of the top b Pin on the 1 8 sq side gluing rails using the lines as a general guide with the angle of the pins inward Sit the top in place and see if the spread of the sides of the top is about right If not re pin the rails and try again 106 Bevel the edges of FT to fit inside of the back of the plastic top This operation must be done in conjunction with the glu...

Page 18: ...ty onto the 1 8 strip of exposed fuselage side and start a rudimentary fillet shape 6 After the Epoxolite has gotten partly stiffened shape the fillet further using a wetted finger or tool of the desired shape 7 Allow the Epoxolite to set up 8 As soon as it is hard but not fully cured remove the wing 9 Trim off the excessthat squeezed into the inside of the fuselage and even the outside edge of th...

Page 19: ...r directly on the plan The grey toned area of the drawing indicates the main frame outline 109 Note that the tip pieces of 1 4 sq are inset to allow space for later installation of rib S 6 110 Cut a piece of 1 4 sq to fit in the center joint of the leading edge 111 Glue in place 112 Mark the locations of all ribs front and back on the 1 4 sq main frame 113 a Tack glue a temporary scrap balsa cross...

Page 20: ...the leading and trailing edges to contour 122 Smooth the stabilizer with a sanding block 123 Glue 3 32 x3 to the top of the stabilizer frame 124 Glue the 3 32 x 3 sheet on the bottom leaving the keying gap exposed There is no gap on the top 125 Continue sheeting the stabilizer doing both sides as you go 126 Leave the front keying gap exposed and unplanked On the bottom only 127 Glue the 5 16 x5 8 ...

Page 21: ...k to see if the stabilizer lines up with it when pinned in place on the fuselage Make sure the stabilizer saddle in the fuselage does not prevent the 1 4 sq main frame keying gaps from sitting down firmly on the fuselage Sand the saddle down if it does If any modifications must be made for side to side alignment be careful not to change the incidence of the tail by disturbing the relationship betw...

Page 22: ...mounted and the plastic top permanently installed PUSHRODS By the time most fliers get to a 60 powered airplane like the King Kobra they have developed their own personal ideas about their favorite types of pushrods Normally we include balsa pushrods for the elevator and rudder in kits and have had good results with them But some builders worry about balsa pushrods in a very fast and aerobatic air...

Page 23: ...nd that your gear does not require all or part of this slot glue scrap foam in it 140 A small sanding tool is handy for making openings in the core for the retracts This one is made from scrap plywood 141 Drill 3 16 holes through the mounting plate and out the other side of the core Epoxy the plate to the foam Cut dowels of the proper length to go completely through the wing to the opposite surfac...

Page 24: ...r so as not to damage the tank See Suggestion 1 on the full size plan before deciding on tank floor installation This more recent method provides 1 8 more mounting space which gets the steering arm higher and farther from the fuselage side 148 Cut out F 2 to pass the wheel This hole could be cut out before the fuselage is assembled if you plan ahead If not a Dremel grinder is a help 149 As previou...

Page 25: ...s because of the well being in the way This piece is inset into the sheet wood of the wing at the back 160 Trace the outline of the fuelage on a piece of 1 8 scrap 161 Draw an inner line inside by the thickness of the sheet used We used soft 1 8 but 3 32 would bend easier 162 a With wax paper between to prevent sticking glue the scrap former to the wing b Add a scrap side former as shown 163 Soak ...

Page 26: ...fset bracket and use of hex head screws will provide a parallel position NOSE GEAR INSTALLATION The wheel collar suggested as optional for the nose gear is not furnished File or grind a notch in the collar so it will fit down on the coil farther The collar permits altering the height of the nose gear slightly if desired Don t try to make large adjustments in nose wheel height with the wheel collar...

Page 27: ...h the material and adhere to the dope already dried into the framework Glue only the outside edges down Leave the rest of the material unattached to be heat shrunk with the iron Trim off the edges with a sharp new blade On the bottom trim off the material flush with the wing all the way around Go over any rough areas or places that did not stick with more dope and press the loose spots down as the...

Page 28: ... painted with 1 8 Stripe Rite or similar plastic tape which will stretch around curved areas on the canopy Mask off the rest of the unpainted areas with wider tape to protect it from scratches during handling If some type of paint other than those mentioned here is used test on a scrap of plastic first NOTE Plan the painting so that the canopy can be glued on the fuselage as soon as the paint is d...

Page 29: ... The fuselage spear is red NO 2 shows the red winged F 16 style King Kobra A variation would be to leave the wing center section white with the red spear on the rear extending on to the nose No 3 is a more complicated version with curves The span wise stripes are blue the fuselage spear is red The red white and blue stripes on the tips are on the top of the wing and stab only Patterns are shown on...

Page 30: ...he wing fuselage joint on it A balancer can be made from a triangular architect s scale placed on a block high enough to get the wheels clear of the bench Shift the model back and forth on the edge of the scale until the balance point is found Balance with an empty fuel tank but with all the other equipment installed and the model completely finished and painted Our findings with 5 prototype model...

Page 31: ...ne or more of the following Airspeed too low C G too far back Pilot pulls too much elevator a mistake aggravated by excessive elevator travel which makes the elevator more sensitive Reduce travel of elevator and use more care in transmitter stick movement Not enough power too high a wing loading for the available power or both Be certain to carefully range check your radio equipment and see how it...

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