Mikoyan Gurevich MiG-21 Bison Firstly, we at Green Air Designs would like to thank you for purchasing our MIG – 21 Bison kit. The MIG-21 (NATO designation “Fishbed”), which first appeared in 1956, was to continue operationally until the late 1970s. Production of this Mach 2 light fighter was also carried out in India, Czechoslovakia and the Peoples Republic of China. In all some twenty countries flew MIG-21s - so there are plenty of interesting colour schemes to choose from. The GAD 1/13 scale MiG-21 Bison has addressed the true fighter performance problem; by fitting a 68mm fan you will get blistering performance, yet using sensible sized batteries you will also get the duration you want. The large wing area gives a low wing loading, excellent glide performance and comfortably controlled landings. The stall is a non-event. Building the MiG-21 is not difficult but care must be taken in some areas but there’s nothing drastic, anyway, those areas needing care will be pointed out to you as you progress through the build. Specification Span 28” Length 48” Approximate weight with 4 cells – 28oz (3s 24oz) Motor. GAD 2836 3700kv Thrust 32oz (64mm GWS EDF 4300kv 2040 motor (3s) 20oz) Battery. 2250 – 2500 Mah 4cell Li-Po (3s 1700-1800mah) EDF. 68mm Wemotec Mini fan or equivalent, is the preferred performance option Servos 2 x 5g (ailerons) 1 x 9gram 1.6 kg/cm at least (Elevator) Hs-81mg or equiv. for 4s and up. Other equipment required to build this model. Hot glue gun Epoxy UHU-por glue

1

Light weight filler - Polycell “One fill” or similar. Home made sanding board. (At least A4 size, made from flat MDF etc, with medium sandpaper glued to it) Making the Fuselage. On opening the box you will see eight blocks of foam, not surprisingly numbered 1-8, (I told you this was an easy build). There are two blocks per number. Remove the pair numbered ‘1’ only at this stage. We do this for two reasons, 1) if you took them all out to “have a look” your bench would very soon become full of clutter, as there is a lot of waste block to make one shell. 2) Damage to the shell formers you are not yet ready to use. Back to former 1 (F1 from now on) as you can see, F1 comprises of two equal but opposite clamshells, which must be stuck together using your hot glue gun, to make a proper F1, (using the sanding board you made earlier????) LIGHTLY rub the two mating surfaces on it to remove any imperfections caused by heat from the laser cutting. Offer them up to each other to check the fit. When satisfied mark with a felt pen, on the inside surface, which face mates to where; you need to do this as when you use your hot glue gun you will not have time for trial fits. Apply glue to the two surfaces of ONE shell and immediately offer it to the other half, making sure the marks you made earlier are right and all is square. Hold in place with your fingers for a couple of minutes. Congratulations! – You’ve made F1, now there’s only seven more to go using the same technique! When finished they should look like this and the photo below.

All halves are assembled the same way.

2

You can now glue F1 to F2, F2 to F3, F3 through to F6, after checking first that the mating surfaces are both flat and square to one another. See photo below prior to gluing.

DO NOT at this stage; glue F6 to F7, (just tack or tape it) however, you can glue F7 to F8. To familiarise you with how they all fit together, see photo below.

3

After all that excitement its time to do some basic gluing, more to make sure you don’t lose any bits than any other reason. Next remove the circular rings, numbered 1-2. Number 1 is the thin ring and will fit at the front of the aircraft when ring “5” is glued to the front of F1. Please note that at the bottom of each ring there is a small hole for the pitot head. These should be aligned using a piece of wire push rod or something similar. Also be aware that one of the rings has four slots in it, these are for the wood strips, which hold the radome in place in the nose air intake. More later.

You should also keep safe the inner circular pieces of the rings that are used to make the radome later. Glue the rings together using UHU por and place in the box for safekeeping. Tack or tape the front and rear fuse together so that you can mark up the wing spar holes and elevator shaft using the simple jig we will now make. Making the jig Locate the Depron pieces marked “jig”. This is pretty much self - explanatory and only requires 2 marked pieces of Depron to be glued to the thin Depron sides. See below.

4

Elevator stub shaft holes Mark out the holes in the rear of the jig with a pen, then using a Dremel or the carbon tube itself, make the holes sufficiently large, but not sloppy, for the carbon fibre rod to rotate in. Locate the ply square, which has the elevator horn and two off ply stub x-spar bearings lased onto it. Slide the elevator horn onto one end of the stub x-shaft and glue it with epoxy, next place the larger of the ply bearing squares onto the shaft and push the shaft outside F8. After sliding the smaller square onto the protruding shaft push it up close to fuselage and check the position of the horn and its movement. When happy, epoxy the inner square to the inside wall then, making sure that the shaft is horizontal to the rear fuselage, when happy, glue the outer square bearing to the fuselage. Rotate the shaft a few times to make sure that you haven’t glued it to the bearings. Repeat for the other side. See below.

5

Take some time over getting the shafts horizontal to the rear fuse before gluing on the outside ply bearings. Getting this wrong will cause all sorts of problems down the road!!!! Elevator Linkage Photo Explanation...

Parts only Horn glued to shaft and small spacer slid on.

Both shafts popped in Outer ply glued on. (See previous page) If any glue gets into the hole, remove whilst wet, or if using hot glue let it go hard, then trim out with a scalpel! DO NOT let the shafts become glued into place!

‘Z’ bend one end of your wire push rods. Stubs popped back in. (View-upside down!)

6

Root out spine and fit servo Take one of your servos, centralise the arm with your TX/RX, and push it into the top of F7. Make and connect the push rods between the two stubs and the servo. The elevator arm should be centred when the servo is at neutral. Make sure that the servo is as high as possible into top of F7 (to clear the EDF unit); some adjusting may be required before you glue the servo into place using Hot Glue! ELEVATORS

Sand the elevators to a symmetrical shape. Mark up and cut the slots as previous page. Offer up the elevators to the rear fuse with 8mm (ish) of the root showing rearwards of the rear fuselage. Mark out the slots required for the elevator stub shafts, scalpel out. Don’t glue into place until the wings are fitted!! Laminate up the rear radome. Glue on the rear efflux tube support (this also carries the afterburner system if purchased)

7

3 Laminates. UHU Por’d together. Glue into place and blend into fuse.

The EDF installation (In F6) a) First you must make sure that the rotor of the fan is balanced. Prop/rotor balancers are readily available – use one. Failure to balance the fan can result in severe vibration and an increase in current draw in any EDF model, not just the GAD MiG-21Bison b) The motor /ESC leads must exit the fan housing downwards to one side at 45 deg (ish) so that they can be connected to the ESC in the bottom duct (and leave room to get the wiring in, things are little tight in here). You will have to extend the two ESC/ battery leads so that they easily reach a point 3” ahead of the front of F4. The ESC/RX lead should also be extended so that it reaches a point 2” ahead of the top duct of F4. The RX resides at the front of F4 in this duct. The lead, from the elevator servo, will also need to be extended to reach the same point prior to gluing F7 to F8. c) When you are satisfied with your EDF (motor running in the right direction?) the time has come to glue it into the rear of F6 using your hot glue gun. You will need to push the outer casing of the EDF into the back of F6 by about 6mm when gluing. See below

8

(The Depron pieces shown in the photo are only needed if you use a 64mm EDF (GWS/Sapac)) Take .25 styrene efflux tube and roll it into a shape that is a good fit around the EDF outlet. Reinforce the joint with strong tape. Test fit the duct tube to the outlet of the EDF. N.B. When taping the efflux tube to the EDF, make sure that it is straight - (horizontal to the fuselage) or the F7/F8 part will be a pig to fit later, and the elevator linkage will bind!

To fit the tail duct to the EDF you will have to feed it through F7/F8 along with your extended servo lead. (This needs to be long enough to reach the front of F4) If you feel like a break before embarking on the wing build you can make the fin by gluing the two 6mm Depron pieces together using UHU por. When set, sand to a vertical taper – 6mm at the top, 12 mm at the bottom. (Sand the taper from both sides!!) Round the front to an acceptable section and then --- again removing material from both sides, sand the trailing edge to 3mm. Be careful not to break off the small projection at the bottom.

9

We have one last job to do before starting the wing that is to mark on the fuselage the positions of the wing x-spars. To place them in the correct place we will use the jig we made earlier.

Holding the jig securely in place, mark the position of the two squares on either side for the spars. Also mark the aerofoil shape onto the fuselage sides. See above photo where part of this is shown. Moving to the front of the template, press the shaped pieces to the side and fuselage top and mark out the area of the cockpit hatch. When happy with this, cut out the hatch. See below. (After removing the cockpit hatch section you may notice a loss of rigidity in the fuselage at this point, therefore we suggest that you line the inside of the fuselage, for at least the length of the hatch, with brown/tissue paper glued with thinned PVA. --- Or, thin glass cloth and your favourite resin to a depth of 50mm should suffice.)

After marking all the holes with the jig, glue on the wing root flares.

10

Building the wing The top and bottom wing skins arrive with you in ONE piece. Lets keep it that way!! To ensure this happens turn the lower surface upper most (scored leading edge down) and run some 2” packing tape along the leading edge. This will support the LE when we come to fit the top skin. Turn the wing over and let’s fit some ribs. Remove the wing ribs from their scrap. There are five of them all marked, 1 is the root rib. This gives strength at the root and either side of the aileron aperture. After you have test fitted the wing ribs into their positions and fettled where necessary, hot glue them into place on the marked etchings. See below.

NB. Slide two wing x-spars into position before making the rear wing spar as the rear x-spar passes through it! DON’T glue them into position yet!!!

11

The above photo shows a finished lower wing with the aileron spar fitted and both the front and rear spar depths “made up” to the height of the wing ribs. This not only increases the gluing area of the top skin, but also creates a series of “boxes” within the wing, which adds to its stiffness. Whilst the x-spars are in the wing you can, if you wish, glue balsa/Depron strips either side of the spars, to make a channel for them – this is optional and up to you. Lay the aileron servo onto the wing skin and using extension leads, making sure there is enough lead to reach the fuselage, pass through the wall of the fuselage, be taped to the inner wall for a couple of inches, pass into the top spine and reach the RX at the front of F4. Check this with a piece of string if you have to, but get it right. Once you have extended the servo leads you can hot glue the servo into position. Remember that the servo arms points DOWN and the servo arm will need to be centred. See below.

The aileron horn is fixed to the aileron about 25 mm out from the inboard end of the aileron, so the servo has to be glued in a position to align with it. Now would be a goodtime to make holes in the wing ribs for the aileron servo cable. See below.

With the cable threaded through the above holes, mark where you need to make a hole in F5 (through the wing flares) so that the lead can pass through into the airway. When you have

12

made this hole you can place your hand through the cockpit hatch and make a hole in the spine so that when you come to fit the completed wing, you are able to feed the cable through to where it needs to end up, namely the RX! Repeat all the above instructions for the other wing. Lightly sand away any “bumps” which would spoil your fitting of the top skin, also try and equalise their weights. Fitting the top wing skin Clear your bench sufficiently so that you can lay two pieces of 3mm scrap Depron onto the bench, one under the leading edge and one under the trailing edge to support the wing. Starting from the front apply UHU-por to all the surfaces that the top wing skin will come into contact with. Gently but firmly raise the top skin, bending it at the leading edge joint, and fold it back on itself until it is covering the formers and the two trailing edges meet. Hold in place until the glue has set. When the glue has set the wing should have stiffened considerably. However, you can make a brown paper /PVA capping strip to run along the leading edge if you wish; 12mm top/bottom should do as all you are doing is reinforcing the LE It should help all those dead stick landings in rough grass fields. Repeat the above for the other wing. When you have top skinned both wings it is time to make the ailerons. This is simply a matter of gluing with UHU-por two sets of aileron pieces together in sandwich. When set bevel the leading edge to take a central hinge and bevel the trailing edge down to 3mm. Remove material from both sides. See below

Using the Mylar supplied, fit the hinges. See below.

13

The position of the aileron horn is shown in the photos above.

Make up and fit the aileron pushrods. (We have used tape hinges in this example) Make sure that you are happy with the length of the elevator and ESC / RX cable lengths, i.e. they will reach the front of F4’s top duct, and that the ESC battery cables easily reaches a point level with the front of the cockpit hatch. This is about the last opportunity to give the fuselage a complete sanding and to blend in all the formers using Pollycell “one fill”, or a similar lightweight product, before you glue in the wing spars and fit the wings. The wing spars should be glued in using hot glue. Before gluing, make sure they are centralised and an equal amount of spar protrudes from each side of the fuselage. Measure twice –glue once! Remember the short spar is to the front, the long one to the rear. Glue them in place.

14

Feed the aileron cables through the hole you made earlier in F4. Spread epoxy on the aluminium wing spar and the root rib of a wing and press the wing into position on the side of the fuselage. Hold secure until the glue has hardened. Repeat for the other side. When the wings are firmly attached, turn your attention to the two aileron servo leads dangling inside the fuselage. From the cockpit hatch, cut a small hole in the top duct of F4 at a point above the wing, and feed the aileron cables into the duct so that they can reach the RX. Repeat for the other side. You should now tape any cable in the airway to the fuselage side using strong adhesive tape. If you wish, and it isn’t a pre-requisite, you can streamline the x-spars by spanning them, front to back, top and bottom with thin balsa and gluing a streamlined strip to the front face. The battery will sit on a thin ply plate (scrap) glued to the floor of F5/4 beneath the cockpit hatch; use your usual Velcro strip and strap to secure it. This method will give you flexibility when optimising your CofG. The battery cables can be pulled up out of the lower duct to the battery. Having the battery in the airflow will aid its cooling considerably but it doesn’t do much for the poor ESC pulling 40 AMPs sealed in the lower duct! So make a small forward facing scoop out of thin plastic or similar material and securely glue it around a hole made in the lower duct at a point behind the battery so that air will be directed into the duct and along to the ESC. You will need to make an exit hole at the rear of the lower duct for the air to exit. Shape the elevator halves to an aerofoil shape and using epoxy, attach them to the elevator x-spar – always sighting them to the wings for alignment. You can now fit the fin using hot glue or epoxy, again sighting to be true in all planes. Turning to the front, if you have sanded the front air intake lip to a thin section, you will need to reinforce this. There are various options available to you, pva/brown paper, tissue/pva or thin glass-cloth and water based resin, whichever system you use, just make sure that you don’t fill in the four radome slots we mentioned earlier.

15

Speaking of which, you should now locate the small inner Depron disks we mentioned at the beginning of the build; we now need them. One of the discs has four notches in it. See photo on page 4 for clarity. Take this disc and the small “lollipop” stick (which must be cut into four pieces), so that when they are glued together the radome should sit centrally in the air intake. See below.

When you happy that this is so, glue the assembly into place. Glue the remaining discs behind the notched disc. The moulded cone glues to the front of the notched disc. See below.

The moulded canopy is shaped and glued to the top of the canopy hatch. Before you glue this on you will fit a 1/16 (its actually 1/13th scale, but it will look good anyway!) scale jet jockey and give him an office wont you? Tongue at the front and a magnet/velcro at the back holds the hatch in place.

16

Whatever finish you use to decorate your model make sure it is foam-friendly. GAD cannot accept responsibility for damage caused by the use of inappropriate paints Slide on the rear fuselage and glue in place with the elevators horizontal with the wings. NOW WE HAVE AN MiG-21 Bison

(pic needs replacing)

Set up: Centre of Gravity: 160mm from the leading edge at the root (up against the fuselage) Aileron movement: 10mm each way as a good start (adjust to taste after first flight) Elevator movement: 25mm each way.

17

Addendum: You can fit our off the shelf undercarriage!

Trim down plastic. Glue together supplied ply and fix with a single screw.

Mark and cut out bottom skin (using Mig-21 Drawing as guide for positions), then using a bit of 6mm depron scrap, glue this into top skin. Glue in the assemblies you have just made securely!!!!

18

Nose Leg:

Glue together the 2 pieces of ply and glue them into bottom of the nose. Cap off with scrap ply so that the plate is flush with the bottom of the battery rails. The legs are NOT glued in, but are an interference fit so that you can remove them for flight if you wish! There are many lumps and bumps all over the Mig –21 make these from scrap Depron and add them...It is an easy way to add authenticity. Missile rails are glued in the open slots in the bottom of the wings. See the 3 views for position reference, Many thanks again to John Ransford for writing this manual and making sense of our deranged meanderings. Once more we thank you for purchasing our kit, we hope that it provides you with many happy hours of ownership and flying.

19

20