4-40 (oz14906)


4-40 (oz14906) by Doc Mathews 1985 - plan thumbnail

About this Plan

Ace 4-40. Radio control sport model. Wingspan 57 in, wing area 590 sq in, for Four Cycle .40 engine.

Note this here is the Ace 4-40 plan. Not to be confused with the Ace 4-40 Bipe (oz6271).

Note this is a scan of the 4-40 plan as supplied in the Ace kit (as opposed to the MA mag version of Dec 1984). In the kit, sheet#1 was printed at 50% size. This version here has been scaled up to fullsize.

Quote: "ACE 4-40 Assembly Manual.

A fitting introduction is a few quotes from the designer's (DB Mathews) construction article that appeared in Model Aviation Magazine:

Our design objective was to develop a model to best utilize the potentials in four-cycle power plants. These remarkable engines produce outstanding pulling power rather than high speeds. For that reason we felt that a relatively low wing loading would produce outstanding flight qualities. Fortunately, we were right on target.

Those who have witnessed the 4-40 in flight are nearly universal in their reaction: the sound is that of a model at low throttle, yet it is incredibly agile.

The four-cycle seemingly shifts gears to maintain a steady rpm through any aerobatic maneuver. The 4-40 doesn't go screaming around the sky; it just sort of chugs away in a delightful mannefr. We also have flown a 4-40 with a Schnuerle .25. With that engine, so much was lost in 'style' that we quickly removed it. With a two-cycle, the 4-40 is just ordinary; with a four-cycle it is extraordinary.

Now that we're sure you're anxious to start, we won't praise this airplane any more. You'll find out on the first flight what Doc Mathews is talking about!

Read through the instructions and familiarize yourself with the parts. Note that the wing is the only full size plan. Some have commented that they'd rather see full size plans and we can appreciate that but full size plans are certainly not necessary to build the plane and their printing cost is very high - which would have to be reflected in the kit cost. The only reason for full size plans would be to cut out new parts in case of a crash. If you feel this may be your case, it may be wise to trace off all the parts and file them in case disaster strikes. Of course, we'll be glad to sell you a new kit as an alternative!

Fuselage Construction: Be careful when punching out the lite ply parts. Clean up the edges with a sanding block so you get a good fit.

Without glueing, fit the fuse sides, F2, F3, and the fuse floor together, noting that the tabs in the floor fit into the slots in the formers. The floor holds the structure square. When satsfied with the fit, glue these parts together by tacking together with thick CyA in all the corners, then running a bead over all the joints.

Glue a tail post to the inside of the rear edge of both fuselage sides. Don't join the rear together yet.

Take a piece of paper as long as the fuse and draw a line down the middle; at one end, draw two lines parallel to this line 1-13/16 inch on either side about 16 in long.

Position the fuse upside down on the paper with the front lined up inbetween the parallel lines. Keeping the fuse flat on the surface pull the rear of the fuse together so it lines up with the center line and clamp. Check that the sides are perpendicular to the surface and every thing is aligned properly. Glue the tail together.

Using a 3/16 bit, drill the firewall for the motor mount. We recommend the Hayes AL-40 if you're using a 40 four stroke. The mount is centered left to right and the thrust line is 1-3/16 in down from the top. Use 6-32 screws and blind nuts to mount. The holes for the throttle linkage and the fuel line can be drilled later.

Using epoxy, glue the firewall and 3/16 x 1/4 in hardwood braces to the fuselage (cut 2-3/4 in pieces from the 12 in length furnished). The firewall should be flush with the front edge of the fuse sides..."

Direct submission to Outerzone.

Update 4/11/2023: Added kit review from Flying Models, December 1985, thanks to RFJ.

Quote: "FM Product Review: ACE RC's 4-40, by Dick Gibbs. For all four stroke lovers, this sport/trainer takes advantage of the latest powerplant craze.

For more than thirty years, ACE RC Inc, Box 511, Higginsville, MO, 64037, has supplied R/C hobbyists with electronic parts, support equipment, and radios as kits or fully assembled units. About fifteen years ago, ACE began production of their own line of aircraft model kits and one of their first efforts was Dick's Dream, a small all-balsa cabin type with a foam wing. Recommended power was an .020 glow engine and flight pattern was controlled by rudder alone. As a complement to the plane, ACE provided the Pulse Commander single channel radio system which provided proportional control used on the rudder of Dick's Dream.

You're right, that's all history now. But what a contrast compared to ACE's current radio system, the seven channel Silver Seven, and their recently released kit, the 4-40, the subject of this review.

The model: The 4-40 was designed by Dr. D.B. Mathews to take full advantage of the 'different' kind of power produced by a four cy-cle glow engine swinging a large prop. A shoulder wing design with a 59 inch wingspan and almost 600 square inches of wing area, the 4-40 is lightly loaded (16 ounces/ square foot) at an all-up weight of four pounds. Aileron equipped, the model requires a four channel radio. Designed specifically for the .40 size four stroke engine, the 4-40 will fly with a .25 two cycle.

The kit: The 4-40 kit is ACE #50K223 and lists for $54.95 in their current catalog. This is a very complete kit and engineered to high standards. Wood quality (balsa, light poplar ply, spruce, and plywood) ranges from good to excellent and die-cutting, where used, is clean and accurate. Sheet and stripwood are separately bundled and one-piece fuselage sides, packed on the bottom of the kit box, emerge unwarped.

The hardware package is very complete and includes Golden Rod nylon push rods, control horns, devises, hinges, aileron linkage material, tail wheel bracket, glass cloth, nuts and bolts for wheel axles, 6-32 blind nuts and bolts for engine mount, and pre-shaped tempered aluminum landing gear. Wheels and engine mount are not furnished in the kit. Other goodies in the box are pressure sensitive decals and an excellent canopy. Tail section parts are 3/16 inch sheet balsa cut to size as is the aircraft grade plywood firewall. Balsa blocks are supplied for fuel tank hatch cover, cowl cheeks, and wing tips. All parts in the box were well packed and nothing, in the kit I received, was scratched, bent or broken.

Plans are rolled (thank you, ACE!) and accompanied by a seven page construction guide well illustrated with photographs. Plans are printed on both sides of a single sheet with one side devoted entirely to the wing and both wing panels are shown (thanks again, ACE!). The reverse side consists of a half-size drawing of the fuselage and tail section, topped off with a beautiful cutaway isometric drawing. Half-size drawings can be a handicap but in this case they definitely are not; along with the building guide photos, the cutaway drawing, and the clever type of fuselage construction, building success is almost assured. If, on the other hand, you find half-size drawings irritating because you're thinking of scratch building another 4-40 don't despair - simply outline the full-size parts on a clean sheet of paper before you use them.

Construction: Although this is hardly a difficult kit to put together, it would be wise to read the construction guide before starting to work. ACE has developed a very logical building sequence which, in conjunction with the plans and cutaway drawing, makes building the 4-40 simple enough for even the raw beginner. Anyone who has previous experience building R/C kits will be amazed at how easily and quickly this one goes together.

I used epoxy to join the wing halves and to mount the tail assembly to the fuselage; everything else, including the firewall, was joined with Hot Stuff (regular and Super T).

Fuselage construction is started by making a box out of the fuselage sides, two main bulkheads, and radio compartment floor. These are all die-cut poplar ply with tabs and notches; simply click them together, hold in place with a couple of rubber bands, and run glue along all the joints. The pieces in my kit fit perfectly and created the basis for a square, true fuselage. Formers and cross pieces are also poplar ply and fit into notches already cut in the fuselage sides. Add stringers, landing gear backup plate, firewall, and, in short order, the basic structure is complete.

The plans call out a Hayes AL-40 engine mount which was unavailable to me so I substituted a Tatone aluminum mount which was predrilled and tapped for the O.S. FS .40 engine. At this point, I added a 2-1/2 inch Goldberg spinner and mounted the engine in the fuselage so I could fair the cowl blocks into the spinner. A few minutes of sanding here will create a nice clean front end that will make you happy every time you start the engine.

Wing construction, like the fuselage, is quick and easy. To free flighters this will be familiar work with multi-spars of spruce and balsa. Sheet balsa is used only in the center section and trailing edges. Two of the four pieces of trailing edge stock in my kit apppeared to me to be on the soft side..."

Update 5/11/2023: Added article from MA, Dec 1984, thanks to rocketpilot.

Update 7/11/2023: Added kit review from Model Builder, September 1986, thanks to RFJ.

Supplementary file notes

Article (MA 1984).


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4-40 (oz14906) by Doc Mathews 1985 - model pic

  • (oz14906)
    by Doc Mathews
    from Ace RC
    57in span
    IC R/C Kit
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 23/10/2023
    Filesize: 995KB
    Format: • PDFbitmap
    Credit*: dfritzke
    Downloads: 699

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