Product Junior Model Kit
Code AJ25
The complete collection of parts necessary to build F1A Junior model: 100% ready ribs, spars, edges, fuselage parts, tailboom, rudder, wingjoiner, polyester tissue and all the other small parts. Using CA can be assembled in few days. If your son or friend is thinking of entering the exciting field of building and flying free flight, or if you’re looking for something that is easier to build and offers great flying enjoyment -we recommend Junior model kit. Comes together with full size plan, step by step building and flying instructions. (AJ25) Parts list.
FMD&C Magazine Review on W Hobby F1A Junior Kit
Material Balsa, Spruce, Carbon
Price (EUR) 125.00
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F1A Model Kit JUNIOR
Nr. Detail Qty. Material
1. Wing Rib 2 Plywood
2. Wing Rib 10 Plywood
3. Wing Rib 4 Balsa
4. Wing Rib 4 Balsa
5. Wing Rib 38 Balsa
6. Wing Rib 4 Balsa
7. Wing Rib 2 Balsa
8. Stabilizer Rib 3 Balsa
9. Stabilizer Rib 18 Balsa
9A. Top Spar 2 Spruce
10 Bottom Spar 2 Spruce
11. Wingtip Top Spar 2 Balsa
11A. Reinforcing Spar 2 Spruce
12. Wingtip Bottom Spar 2 Balsa
13. Trailing Edge 2 Balsa
14. Leading Edge 2 Balsa
15. Wingtip Trailing Edge 2 Balsa
16. Wingtip Leading Edge 2 Balsa
17. Stabilizer Leading Edge 1 Balsa
18. Stabilizer Trailing Edge 1 Balsa
19. Stabilizer Top And Bottom Spar 2 Balsa
20. Covering Sheet 2 Balsa
21. Covering Sheet 2 Balsa
22. Additional Material 1 Balsa
22A. Web 5 Balsa
23. Body Shell 1 Glass/Carbon
24. Frontend Block 1 Wood
24A. Timer 1 Steel
25. Towhook 1 Steel
25A. Towhook Cover Plate 1 Steel
26. Stabmount 1 Balsa
27. Tailboom 1 Carbon/Glass
28. Rudder 1 Aluminum
29. Mounting Screw 4 Steel
30. Towhook Adjustment Bolt (with Bushing) 2 Steel+Brass
30A. Towhook Pin 1 Steel
31. Line 1 Fishing Line
32. Rudder Line 1 Wire
33. Straight Tow Adjuster 1 Wire
34. Line Tube 1 Plastic
35. Wing Fixator Wire 1 Wire
36. Piece Of Lead 1 Lead
37. Wingjoiner 1 Steel
38. Tissue 1 Polyester Paper
39. Full Size Drawing 1  
F1A Model Kit JUNIOR
W Hobby “Junior” is easy to build -no special skills and additional materials are needed. All details can be glued with epoxy or CA.
Wing: Use the full size plan enclosed into box. Mount trailing edge to the board over the drawing using thin nails. Put some balsa sticks under the edge and ribs as shown in view E-E. Glue ribs into the trailing edge, place the leading edge in front, and glue it to the ribs. Glue on the top spar. After that take the wing off, turn it upside down and glue on the bottom spar. Then fill the space between spars with balsa pieces cut from sheet (22A). Place wingjoiner stop (22) and then cover ribs with balsa sheets (20, 21) as shown in the drawing. Press the sheets to ribs or mount with nails until glue dries. Put the balsa triangles (22) to force construction. Brush the wing to smooth surface.
Wingtip: Collect it the same way as central part, but cut the trailing edge after completion as shown in the drawing. Brush the tip rib (7) as shown in H-H. Cut the ribs (6) 10? off to get 20? at dihedral. Join tip to root panel. The wing is ready to cover.
Use the tissue enclosed or any other material (Japanese paper, Mylar, etc.). Use cellulose dope for paper covering (nitro dope is available in any hobby shop).
Stabilizer: The same construction, only some additional work - brush the edges after completion as shown in F-F.
Frontend: The construction of frontend is very simple. First of all find out how devices work. You can put them into Frontend Block (24) without the Shell (23) –that allows you to see if everything works well. Then disassemble the frontend and glue (use epoxy) the carbon Shell (23) onto the frontend (24). It is convenient to put some lead inside the ballast space slot before assembling the frontend. Glue the bushings (30) into the top holes of frontend. These bolts adjust the tow and glide circles. The third hole is for access to the zoom bolt on the towhook.
Now brush the frontend outline and paint it the color you like. Put all devices inside and check how do they work. Be sure that the timer starts after the towhook latch is released.
Fuselage: Glue-on the stabmount (29), rudder (28) and plastic tube (34) to tailboom (27). Then thread the lines, connect the rudder line (36) to towhook. Join the tailboom to the frontend, put the wire-adjuster (33) to the other end of rudder line, finish both ends of stabilizer line (35).
Flying: Use 50m of fishing line (0.8mm) to tow model. Towing and gliding circles are adjustable at towhooklocation. To adjust zoom angle take out the cartridge and turn the round-headed bolt on the towhook. Set timer for the 10-20s on the first few flights. To make glide flat adjust the stabilizer’s angle, or change the center of gravity by putting some lead in ballast box. Remember that model’s weight must be not less than 410g according to the FAI rules.

Have a good time building and flying your JUNIOR !
F1A Model Kit JUNIOR
(published in FLYING MODEL DESIGNER & CONSTRUCTOR magazine July 2000)
by Mr.Andrew J. Crisp, UK
If this kit was packaged in a glossy box and made available from the shelves of your local shop, flying fields throughout the land would be choc-a-block with examples of this excellent glider. It could become in modern times what the Inchworm was in the 50 s and 60 s. As it is, it comes in a strange, if stout, wood grain effect box, with no lettering or picture, and is only available to those in the know - more is the pity.
The design is around 2 metres wing span and is almost a dead copy of Peter Allnutt s Checkmate which was drawn and described in FFN2OO, a publication which celebrated 200 issues of Free Flight News. I hope Pete got some acknowledgement for the design. I think that they have been produced ready-to-fly in China as well - the Chinese Checkmate !
Minor differences in the kit include different dihedral layout - flat centre section, which makes withdrawing the wing joining dowel easier from the fuselage, and the sheeting layout at the wing root. The tailplane has less ribs than the original , and has a bottom spar which is webbed to form an I-beam. The fuselage pod now runs right to the back of the wing and is not cut away as on the original.
Junior could be described as an intermediate glider design. It isn’t a rank beginner’s model - not because of its construction (which is more straightforward than many so-called starterjobs), but because of its systems and performance capabilities. Here is an FlA (A/2) design which could be built right from the contents of the kit and flown in competition at the highest level - well, at least until the seven minute evening fly-off round!
Apart from the front fuselage covering shell and rear boom, Junior uses no hi-tech materials or techniques. It is a straightforward balsa, spruce and tissue (albeit polyester tissue!) design, which should be an encouragement to those who find the latest constructional trends alien to them.
From the outset I decided to build the model as per , without being tempted to add those little things you prefer, learned through long experience! This way you get a true assessment as to how the average purchaser of the kit might fare.
The only tools used (or required) were the usual balsa knife, razor blade (sharp for trimming the tissue), sanding blocks and pliers.
Glues were UHU Hart balsa cement, aliphatic resin P.V.A., thick cyano and 5-minute epoxy. Thinned dope was used to stick on the tissue.
There are no printed or die-cut sheets as we know them. All parts are neatly and accurately cut, taped together with the appropriate number on the tape. Unwrap as you go. The stripwood in my example was not of the highest quality, but in general was quite adequate. Some pieces were not particularly straight. J.O D s remark that warped strip leads to warped surfaces came to mind, but harking back to my earlier statement, I didn t replace anything.
The wing halves are joined by two wire dowels - a long front one, 4mm (approx. 9 S.W.G) and a short, incidence locating rear one, 1.5mm (approx. 18 S.W.G). The main dowel is smaller in diameter than I would have used (my current designs have 6 S.W.G. or 5.5mm.), but there again, Junior s wings are probably more flexible. I did change the rear dowel to 14 S. W.G. purely to bring it in line with all my other models, which use that size.
The main joiner passes straight through plywood ribs with no ali. or brass tubes. This is quite satisfactory as there is substantial
sheeting top and bottom. It is a good idea when assembling to slide the appropriate ribs on to the dowel so that the holes exactly line up. Also remember to pack up the ribs at the L.E and T.E. by lmm. to account for the sheeting thickness. The ribs are slightly over length and should be trimmed from the rear only to fit snugly in the ready-cut slots in the trailing edge.
The wood provided for tip spars in my kit was rather soft so I increased the size of the web to 1/8" (3mm.) for a couple of bays at the dihedral joint. Conversely the tipblock wood was unnecessarily hard, so I carved it down as much as possible consistent with keeping the profile shown on the plan. The dihedral joint consists of a large, soft rib at the end of each panel. These are sanded chuckglider fashion to provide a good fit at the correct angle. I used 5minute epoxy tojoin the panels and when sanded down, formed a cement skin top and bottom, so beloved by the late Bill Dean on his designs!
The root sheeting provided was quite hard, but went over the aerofoil curve easily enough. A knife and metal rule should be used to trim up the edges for a good fit.
Finally, remember it is easier to cut the taper in the tip trailing edges before
joining to the centre-section panels.
With all that root sheeting I thought that the wings would turn out heavy but surprisingly, without the dowels, they weighed 140 gm. brut and 135 gm. sanded.
I actually started with the tail to get the hang of the construction. It is a very simple piece of building. Note that all the gussets etc., in the wing and tail are cut rough from a lump of soft block and then sanded flush with the surface after assembly - quite a novel, but good idea.
I find it easier to get a good fit with webs by building in the sequence - bottom spar, webs, top spar. This seems better to me than gluing in the spars, then trying to poke the webs between them.
The tail sanded, but uncovered weighed 7.5 gm.
The fin and rudder are from 3mm. sheet and need to be sanded to a thin, symmetrical section. They are joined with small metal hinges which push into the wood. One was missing in my kit, so I joined the two parts with a sewn cotton hinge - C/L fashion. I have used this system for years and it has never let me down. There is a neat little metal horn which should be epoxied onto the bottom of the rudder firmly. It is not symmetrical. If you want the model to turn RIGHT make sure that the shorter side i.e. for the tension is to the right. The plan shows a rubber band for tension. This is bad news! With a circle tow system with no position stops at the rear end, i.e. at the rudder, the tension needs to be consistent if you try to get the same rudder settings all the time. If you have to change the band (and they do perish), you often change the tensions and hence the rudder settings. A small coil spring gets over all this. Mike Woodhouse sells good selections.
The fuselage consists of a front part, the pod, which contains the timer and towhook (which comes ready fitted), and a boom which fits onto a spigot on the pod. The boom appears to be of carbon and comes painted white. The taper seems sharper than the typical British product, making for good stiffness. At the rear, the tailplane mount is from a light alloy, and is a good fit on the boom in the right position. The pod consists of a wooden core, with holes for timer position and ballast. It is perhaps lime and is quite heavy, as we were to find out later. The works are covered with a carbon sheath which fits accurately and lines up on the small pin which secures the towhook.
The timer, which is supplied with the kit, is single function, the D/T arm coming out of a scroll. There is no on/off switch, like a Tatone or K.S.B. The motion is stopped by a thin wire rod, (approx. 20 S. W.G.), which is connected to the latch on the towhook. When the ring is fitted on the hook, and the latch is engaged, the rod goes forward and interrupts the works of the timer. Even when it swings back to circling position the wire still engages the timer. However, when the latch opens, and the ring falls away, the latch arm moves just that bit further back to allow the wire to move away and permit the timer to start.
Naturally, this needs some fine adjustment to get it all to work! It helps if you put a kink thus in the push/pull wire near the towhook. Then, by bending it in or out with a pair of fine-nosed pliers you can alter the effective length. The trouble is, once the carbon shell is glued in place, and the timer screwed in position, there is no way that you can get at the works . The answer is to screw the timer directly to the hardwood core, and get everything working while it is relatively easy to get at. Now enlarge the timer hole in the carbon cover so that it neatly clears the timer faceplate. The carbon is quite easy to cut using a heavy blade.
On top of the fuselage pod are mounted two screws which adjust the circle and glide towhook positions. They are housed in alloy bosses which are a push fit in the wood of the core. They need to be cyano-ed in place to be effective. I guessed the amount of nose ballast required by temporarily assembling the model, and hammered sheet lead into a block which easily fitted in the space provided. This was epoxied in place. Epoxy was also used to glue on the carbon shell, many rubber bands holding it close to the core as it dried. A certain amount of work was necessary with the sanding block to take away the excess carbon and to streamline the nose entry.
Turning to the boom, the fin was securely glued in place and holes made for the auto rudder line exit near the fin, and D/T line entry, near the front. A good way to make holes in carbon or fibre-glass booms is thus:- Wrap the boom with masking tape at the position required. Tap a pin through, using a small hammer. Now using a fine, pointed file rotate between the fingers to open out hole to size required - in this case about 1/16" (l.5mm.). Remove masking tape.
I must confess I did not use the metal auto-rudder line as supplied. It seemed far too stiff to me, and I replaced it with light weight Laystrate . Plastic coated trace wire, as sold for pike fishing, would be even better. Linking up the A/R to the towhook is made easier by the following method. To the appropriate cam on the towhook fix a short length of wire line, say, 6" (l5cm.) so that it projects well past the spigot of the pod. Fit it to the towhook with a crimped hook. Make a similar loop at the other end. Of course this should all be done before the shell is fitted.
Now pass a longer piece of line down the length of the boom through the hole in front of the fin. The piano wire wiggle shown on the plan is an excellent idea which joins the line to the horn on the rudder and allows easy fine trimming. Again, using a crimped loop, join the main line to the short tag from the towhook. The boom can now be fixed to the pod using epoxy on this important joint. Having already fixed the fin on to the boom makes it easier to line things up.
The nylon line for the D/T is fine as supplied. Ifyou have to replace, use 121b. breaking strain. Finer doesn’t stand up to repeated D/T landings. Much heavier doesn’t go round the corner at the rear end. Make some provision for adjusting the pop-up angle of the tailplane.
Finally glue on the tailmount, making sure that the tail will be square to the wings when the model is assembled.
The Junior kit contains white polyester tissue for covering, very similar to the Salzer tissue supplied by Mike Woodhouse. The panels are ready cut to size with a slight overlap. This tissue has a rough side and a smooth side, although this is not immediately apparent. The contrast is much greater after doping! You want the smooth side outermost. The other absorbs too much dope.
For those who have not used this material before, it has a definite grain, which should go down the length of a given panel, but does not like compound curves - no problem on Junior . It fixes easily in place with dope. Dope the complete airframe with fulL strength. Let dry, and sand lightly. Now dope again with a 50% dope/ thinner, and press tissue in place. Dope through from the top for a really good fix. It is difficult to get this material to lap round leading and trailing edges, but as it is white, it is not really necessary. Trim off flush with a sharp razor blade. To shrink before doping go over the panels with an iron on medium setting. It comes up like a drum! Be careful not to induce warps, especially in the tailplane. I used three coats of 50/50 on the wing and two on the tail, sanding with used wet and dry between coats.
I did not use the stick-on decals supplied with the kit, preferring to add a bit of colour with doped on Modelspan tissue decoration, numbers and letters. The fin and wing tips were given a light spray of flame day-glo for visibility.
Finally, the front fuselage was finished by fine sanding. The carbon was degreased by rubbing with thinners, and then given three coats of dope/talcum powder/thinners mixture as an undercoat to the final Humbrol enamel colour.
The table of weights shows that Junior came out way over weight even with that lovely light wing.
Actually, it worked out slightly less than this, as the C.G. was too far forward and lead had to be drilled out of the nose to get it where I wanted it.
covered, decorated, doped 165 gm.
Tail covered,doped 10 gm.
Fuselage+joiners 275gm. Total 450 gm.
(410 gm. required minimum for FIA)
I know people say that a little extra weight doesn t hurt the glide, but I prefer my A/2 s to be as near to the 410 gm. minimum as possible, keeping in mind the comparison of a feather and a cannon ball being dropped from an upstairs window!
Before venturing to the flying field Junior was set up in accordanee with the plan as near as possible in the workshop. The warps in the wing for a right hand glide turn were adjusted in the steam of a kettle to be:- Left outer panel 5 mm. wash out, left inner flat, right inner 2 mm. wash in, right outer, 3 mnt. wash out. Actually, due to a slight inaccuracy in my building, the whole right wing turned out to be slightly positive, compared to the left. This was thought not to be a bad thing in view of the intended right turn. The tail was flat.
Rudder settings were set up to be (at the rudder T.E. relative to the centre line of the boom) - tow 2 mm. left - circle tow 10 mm. right - glide 4 mm. right. A slight bias to the right came in from straight tow accelerated for zoom launch.
The C.G. was 51 % of the wing chord.
Early March this year saw some good flying weather in Oxford, so I was able to give Junior virtually a week of hard testing - thermal conditions in the day - relative still air at dusk.
First test glides showed the trim to be nearly spot-on, with perhaps the turn a little tight. Not having a helper with me, I solo launched and circle towed from the off. First tows showed a strong right bias on the line which was grudgingly moderated in subsequent flights with a lot of extra left rudder. Jerked launches were quite difficult, the line being reluctant to leave the model. 1t suddenly dawned upon me that the towhook had a depression in its horizontal part. This held the hook even when the latch was open. The answer was to throw the line (without the winch of course). This gave a perfect release every time.
In free flight Junior had a tight, bouncy, thermal-prone glide, good for windy weather flying, but I felt a lower sinking speed could be gotten out of the model with less decalage and a wider glide circle.
My doubts about the wingjoining rod proved correct, and the wings showed some centre dihedral after a few vigorous launches. This appeared not the affect the flying, and probably helped the D/T action, which was gentle and controlled, not the ungainly looking spiral necessary to get high aspect ratio F1A s down.
Before the next flying session the following modifications were undertaken. The wash-in was removed from the right centre wing panel. This was to open the glide and to get away from the excessive left rudder for tow. The C.G. was moved back to 54% by drilling out lead from the nose and filling in the holes with soft balsa. This effectively meant that the towhook was now 20 mm. in front of the C.G which should give less left tow bias and lighten the model into the bargain. A sliver of packing was taken from under the tailplane T.E. to restore the glide, which should also mean that zoom launches could be harder without the looping tendency which had previously been evident.
Junior is not an out-and-out performance machine, but it sits well in the air and, carefully flown, responds to the slightest thermal lift. Despite having no turbulator on the wing (none is shown on the plan), it recovers well from disturbances with little or no rocking around. The coming season should ascertain its competition worth.
For the rubber or power enthusiast who wants a glider on the side without a lot of hassle, Junior is the ideal choice. It would also be ideal for the vintage enthusiast who might wish to break in, by way of a complete kit, to relatively modern glider technique. If the bug bites hard, there are more advanced kits produced by W-Hobby, like the Sija with its tubular carbon spar, reviewed by Phil Owens in the Aeromodeller a while back and two versions of the Superba which are state-of the art bunters with full carbon construction.
Remember - gliders are green, good fun and keep you fit.
**FMD&C** Andrew J. Crisp.

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