The plan build article by Peter Miller - 26/3/10
Another reason for the E’s dumpy appearance, of course, is the very low aspect ratio of that short, 20ft-span wing, whose very thin, slightly under-cambered NACA 4409 section is - interestingly - built-up using a geodetic construction over normal ribs. All that was required to complete the E’s broad-in-the-beam profile was the wonderfully practical fat-tyred undercarriage, again borrowed from Piper’s Cub.
Despite all this, however, I took one look at a three-view drawing of the Model E and saw the potential for a scale model that would be easy to build, full of character, and friendly to fly.
I’ve designed the Fike to be as accurate a scale model as possible, though having said that, it’s worth noting that there were several iterations of the E. In ‘74 William Fike increased the aeroplane’s span by adding an extra 14” to each end of the wing, and in ‘77 the aircraft appeared at the Oshkosh show fitted with a full cowling concocted from a Piper PA11 front section and cunningly bent sheet metal.
My design is based upon the earlier, short-wing version without the cowl. This gave me a model with a wing area of 540sq. in, which I felt would be just right for a .30-size four-stroke engine. The all-up weight of the finished item produced a wing loading of 151/2oz / sq. ft, which is ideal for this type of design, and also gives it great potential for conversion to electric power (though if that’s your inclination, I’d go for the larger span version so that the extra weight of a battery doesn’t increase wing-loading unduly).
Otherwise, in scaling down the Fike, I’ve incorporated only one or two slight variations from the full-size aircraft, in the interests of ease of construction. The first of these was to change the wing section to 10% flat bottomed, and set it at 0° so that the model has, in effect, a symmetrical section. The other change was to lower the thrust line so that the engine will fit inside the cowl rather than emerging from the top.
The model’s construction combines lightness and strength with simplicity. The fuselage, for example, is a basic box with some slight variations, and requires no technique more demanding than keeping everything true by working over the plan, especially when you’re pulling in the sides at the front and rear.
Start by cutting out the various parts for the 3/32” sides indicated on the plan by the hollow arrow heads, but don’t cut out the windows just yet. Also prepare the 1/32” ply doublers, which should be chamfered where the longeron goes over their edge.
Glue the parts of the balsa sides together, and then add the doublers using contact adhesive (I use Thixofix, a glue that gives you some scope for fine tuning the position of components if only light initial contact has been made). Once you’ve got this far, you can cut out the windows.
The 1/4 x 1/8” longeron that runs from F2 to the tail - and which gives the fuselage some resilience under load whilst adding a bit of strength down at the tail end - is fitted next, followed the liteply gussets which take the rear undercarriage blocks and the servo rails. These are fitted behind F2 - remembering, of course, that the servo rail cut-out spacing needs to be matched to your servos. The plan shows 3/8 x 1/2” beech undercarriage mounts, but I made mine from 1/4” ply with two strips of 1/8” ply glued on to make the slot for the wires.
Assembling the two fuselage sides involves cutting almost through the balsa sides on the line indicated at F2, while taking care not to cut into the ply doubler. You then lay one side down on the building board and glue on F2 and F3, making sure that they’re at 90° to the sides. Once dry, you can glue the second side to the first, using a set square if necessary to ensure that the two are perfectly aligned. Before you do this, though, take a look at the plan, which shows pieces of triangular stock on either side of F2 and F3 which help to keep the formers upright. For the most accurate results, glue one of these fillets to one side of each former before fitting, and to the other side once the formers are firmly secured.
BRINGING IT TOGETHER
With the two sides married, pin the fuselage down over the plan, pull in the rear, and join using some scrap trailing edge stock; bear in mind that you may have to adjust the angle of the scrap wood to get the fit just right. Then add F4, F5 and F6, and leave the whole lot to dry before pulling in the front and securing it by gluing Fl into place. It’s vital, by the way, that this former is perpendicular to the centreline.
Once everything is dry, you’re ready to fit the 1/8” liteply gussets (in front of F2) that take the forward undercarriage mounting blocks, as well as all the triangular stock that braces the corners of the fuselage box. This is a little fiddly as, to get the best and strongest fit, you’ll have to sand the triangular stock to match the angles in front of F2 and behind F1, as well as cutting rebates for the liteply gussets.
The next step is to pull in the top of the fuselage just in front of F2, and fill in with 1/8” sheet, following up with the ply plates that take the wing bolts, to which you should have already fitted the blind nuts.
WING SEATS & WET BALSA
Things start to come together quite quickly now. The wing seats are made of 1/4” balsa sheet that’s rebated to fit over the wing bolt plates, the latter being covered by a 1/8” balsa fill-in as shown in the sketch on the plan. The tail wheel mount can also be fitted, along with the tailplane platform, and the bottom of the fuselage is sheeted as shown. You might want to fit the snake inners at this point too, although it’s not too difficult to add them later through the open sides of the fuselage.
Fit the spine, the two 3/16” square stringers, and the 1/8” sheet behind F3. When it comes to the rolled sheet, find yourself some very pliable stock. To help work it into shape without cracking, I glued one edge of this sheeting to the stringers and then, when it was dry, wet the outside of the balsa and applied heat with a heat gun while bending it to shape. I trimmed this first piece to the centreline of the spine and then simply repeated the process for the other side.
Once you’ve fitted the engine mount (use a long lrvine mount for .25 to .35 engines) and bolted the engine in place, all that’s left to do is to make the cowling. This involves building a box using 1/4” sheet for the top and sides, and 1/2” sheet for the bottom and front. If you’re going to build the fully cowled version, of course, you’ll have to add Cl and C2 during the construction of this box, fit the 1/4” square strips along the sides, and then wrap 1/64” ply around the assembly before fitting the 1/2” front as shown.
The wing-building procedure is quite straightforward, and starts with pinning the lower leading edge and lower centre-section sheets to the board along with the cap strips, trailing edge, and the cap strips at the aileron spar and the aileron leading edge. Next, using the ribs as location guides, glue down the lower 1/4” square spar and rear spar. The ribs themselves are added now, using the alignment marks on the plan to position them accurately. However, don’t glue them to the leading edge sheet just yet.
After gluing in the top spar and leaving it to set, fit the aileron spar and then the aileron leading edge, using the aileron ribs to get the correct chamfer angles.
Noting that the aileron ribs are laminated to form a slot for the Paxolin horn, you’ll need to mark through this slot and onto the lower sheet so that you can find the position when you eventually turn the wing over. Then chamfer the lower edge of the 1/8” sheet wing leading edge, and glue it into place, making sure that it is accurately aligned with the bottom of the ribs.
Apply glue to the underside (chamfered section) of the leading edge and the underside of the ribs, and then press the sheeting into place. I use a lot of small pieces of scrap trailing-edge section as wedges for this job, but however you do it, you need to ensure that the wing doesn’t lift, and that the sheet remains in firm contact with the ribs while the glue dries. I find that this is the sort of job that’s made much easier by CA glue, which will wick into the joint. Finally, fit the webs to the front of the spars and then leave the whole assembly to dry before planing and sanding the leading edge to match the ribs.
When you come to fit the top sheet, you can clamp it to the spars with clothes pegs and small clamps - it’s why the web is in front of the spar, after all - before pulling the sheet down to the leading edge and pinning it firmly into place. Short map pins are ideal for this, as they go fully home and the head holds the sheet in firm contact with the leading edge. The small pieces at the tip are added separately.
RODS & CRANKS
Install the pushrods and bellcranks on their mounts, then add the 1/2” sheet in-fill and ply plates for the wing bolts. Don’t try drilling the bolt holes at this stage, though - they can be marked through from the bottom when the wing is complete. Instead, fit the top centre-section sheet and the remaining cap strips - including those at the aileron spar and leading edge - as well as all the gussets and blocks for the hinges.
Once all these parts are well and truly dry, the wing can be lifted from the building board and finished off. This involves trimming the leading edge sheeting flush with the leading edge itself, and then adding the 1/8” sheet cap strip, which is planed and sanded to shape when dry.
It was at this stage that I made the aileron horns and dry-fitted them so that I could fabricate the pushrods, starting at the bellcrank end. Then, once I was sure that everything lined up, I covered the underside of the aileron bellcrank bays with 1/64” ply. The slots for the pushrods, by the way, are close enough to the bellcranks to allow the Z-bends to be fitted to the bellcrank after the wing has been covered.
The ailerons can now be separated from the wing, and the hinge points drilled, although they could always be top-hinged using the covering if you prefer that method. Finally, the tip plates are fitted after the wing has been covered.
The tail parts should be fashioned from medium-hard wood. In order to maintain the correct overall length of the elevator, you might find it handy to make both halves using one length of 1/4 x 1/2” material then, before separating them, drill each piece for the joiner. The elevators are hinged after covering, for which I used Mylar - the sort with tissue bonded on for use with CA glue. The fin extension is simply made from 1/8” sheet, and again it isn’t fitted until the model has been covered and assembled.
You’re probably wondering whether the tail feathers could be simplified further by making them from solid sheet. The same thought occurred to me, but as things turned out the built-up approach meant that the weight of the tail components helped to put the balance point on the finished model exactly where I wanted it, and without the need for any additional ballast.
COVERING AND FITTING OUT
I covered my model with Solarfilm Supershrink polyester, which is the best film I’ve used to date; the lettering and fuselage flashes were cut from black Solartrim.
The undercarriage is made using 8swg wire for the front legs and 10swg for the rear, which gives a little extra strength for those heavier landings on grass. To form the front ‘V’ of the undercarriage, you can use 18swg wire, bending it down on each side to marry with the top of the legs, then back through 90° to meet the rear legs. The bungee suspension connecting the two sides is a simple elastic band strung between the two 18swg front hooks and passed through the V, above.
FLYING THE FIKE
Fitted with an SC 30 four-stroke, the Fike takes-off from a concrete runway in just a few feet, and does nothing thereafter to upset that first impression of being willing and obliging. The stall, for example, is very benign: throttling back and feeding in full up elevator will slow the model progressively until - given a gentle headwind to lean on - she’ll simply hang in the air. One wing or the other will try to drop eventually, but it isn’t difficult to pick them up with the ailerons.
Work the sticks a bit harder and you’ll find that rolls are remarkably axial (though flick rolls aren’t terribly quick), and loops are easy, even if outside loops need a bit more work and some extra height. Inverted flight is very steady, and recovery from a spin is fast and positive. Needless to say, when the engine stops the glide is long and quite flat. Bringing her in to land, I found that the model will try to tip over if there’s any sort of a crosswind; approach dead into wind, however, and she’ll land perfectly.
The 30 four-stroke gave the Fike creditable performance, though for some extra zip you might want to consider a good .25 two-stroke. A .32 two-stroke or a .40 four-stroke, meanwhile, would probably turn ‘Fike’ into something sounding more like an oath!
When designing this model, I made good use of Carlo A Godel’s excellent scale drawings, plus a photo of the 1977 version in Jane’s Pocket Book of Home-built Aircraft, and some history along with a front view of the uncovered airframe in Jane’s All the World’s Aircraft 1968 - ‘69.
That’s all folks, I hope you enjoy the model as much as I.
Model type: 1/6 semi-scale home-built
Designed by: Peter Miller
Wing area: 540sq. in.
All-up weight: 58oz
Wing loading: 151⁄2oz / sq. ft.
Fuselage length: 45''