Radio Control
SCALE
Bob & Dolly Wischer
ON-BOARD IGNITION
A high percentage of Scale models need weight added in the nose to counterbalance a tail-heavy condition. Don't feel bad about having to add nose weight—it's needed on some full-size aircraft too. The DC-4, for example, carried about three-quarters of a ton of ballast in its nose. Nevertheless, adding weight to an already-burdened Scale model can seem wasteful.
A convenient (and useful) five-ounce nose weight is a 4 amp Ni-Cd D-cell that can also be used for on-board glow ignition. Reliable engine idling and positive throttle response under all conditions are benefits of using the cell. All D-cells are not alike. The common inexpensive variety found in electronic retail stores is much lighter, is rated at 1.25 amps, and is really a C-cell in a D case. Most glow plugs draw about three amps, which results in a very short useful life between charges if a 1.25-amp D or C cell is used in place of a four-amp cell. We use the GE 1.25V, 4 Ah model HD1000.
There are several ways to use a cell for on-board glow ignition:
- Direct connection to the plug. Use an On-Off switch somewhere in the model—preferably near the receiver switch—to avoid overlooking it at the beginning of a flight. Turn it on when the flight begins and off after landing. Current flows throughout the flight and engine idle is ultra-reliable. A freshly charged cell has a life of over one hour. Mount the cell on a plywood plate with an aluminum strap, assembled to the engine mount and positioned as far forward as possible for best weight distribution.
- Throttle-actuated lever switch. A sub-mini lever switch (e.g., Radio Shack No. 275-016) actuated by the throttle servo linkage can energize the glow plug only at low throttle positions. This greatly extends battery life compared with the simple system. It is advisable to use an On-Off switch in series with the lever switch even though it isn't strictly necessary; without it the pilot must remember to disconnect the battery at the end of each flight, which is easily forgotten.
Using the cell only at low throttle, a fully charged cell will last through a dozen flights. Keep wire leads to the cell short; preferred wire size is No. 18 stranded for current-carrying capacity.
The Off switch (single pole) should be capable of carrying three amps. A double-pole switch with the poles connected in parallel will carry twice the rated capacity. Recommended small, light slide switches include Radio Shack No. 275-401 (single pole) and No. 275-403 (double pole). Slide switches with silver contacts are preferred for current-carrying and vibration resistance. The Noble switch used in radio installations is another option.
A compact, reliable connection to the glow plug can be made by soldering a wire to a brass wheel collar. Clamp the collar over the plug tip with its set screw, making certain it does not touch the cylinder head. If in doubt, use an insulating washer under the collar to avoid a short circuit. If the cylinder-head collar doesn't protrude above the glow plug terminal, the collar will fit inside a tight engine cowl space. A commercial glow connector can be used in place of the collar; Model Products Corp. markets the Head-Lock Remote Single Glow Plug Connector. A permanently wired remote on-board jack could be modified to accept an on-board battery.
Everyone has a favorite system for connecting an external starting glow battery. Many recent Scale models are equipped with the sub-mini phone jack used on small personal radio receivers (Radio Shack No. 274-292), mounted in an inconspicuous location inside the rear edge of the engine cowl where it can easily be reached. The on-board battery is wired through the jack so it is disconnected when the external-starting plug is inserted; this avoids the problem of mismatched polarity on the starting battery's leads. When the external starting plug is removed, the internal D-cell is reconnected into the circuit—the contacts for making and breaking the internal circuit are part of the jack.
After an on-board cell has been installed, the external starting battery often isn't required any longer. With the simple system, merely flip the switch and the engine is ready. If a throttle lever switch is used and the second On-Off switch is omitted, there is always the chance the pilot will forget to open the throttle at flight's end and will run the battery down. Even worse, some unsuspecting modeler may flip the prop and get a nasty surprise from a whirling prop on a live engine. We are programmed to think an engine is dead if no external battery is visible. This is not a joking matter—it has happened and represents a real hazard. The second On-Off switch prevents accidental engine start-up.
LETTER FROM DALE
From distant Saudi Arabia come these thoughts by Dale Johnston:
"You haven't heard from me for a couple of years (not since the scale speed controversy). I cannot, however, hold off any longer on the Precision Scale/Sport Scale issue. The expressed purpose of Sport Scale was to increase Scale model activity, which it has. The rationale was to encourage participation in Scale by reducing the requirements. The escalating number of entries in Sport Scale since its inception is self-evident of its success. Let's not foul up a good thing when it's working! Changing the Sport Scale event when it's doing exactly what was wanted doesn't make any sense at all. The problem is that Precision Scale modelers are 'dumping' into Sport Scale through the path of least resistance. There is no incentive for them to participate in the more difficult event.
"Sport Scale should be for the less-adept, who should be encouraged to advance to Precision. Conversely, Precision modelers (ideally) should not be permitted in Sport Scale. We don't allow advanced competitors to regress in Pattern! I admit, however, that this correlation is not perfect, since it compares flying skills with building skills. If applied to Scale, it might significantly reduce participation. The alternative, then, is to restrict the model instead of the modeler. Precision detail on the model entered in Sport Scale events must be penalized, just as the lack of same is penalized in Precision Scale. The best way to turn the existing situation around and get Precision models back into their own event is to deduct points for cockpit detail, rivet heads, and 'other things not visible in flight,' when they are entered in Sport Scale. On the positive side, the Precision Scale event should be officially recognized as the ultimate in Scale. This should be perpetuated at contests by awarding larger trophies, better prizes, etc. Sincerely, Dale R. Johnston, AMA 1033."
Being longtime Precision Scale modelers ourselves, we would like nothing better than to see our event perpetuated. When Sport Scale was introduced, Precision began its skid downward, and our answer to anyone hoping for its revival is a question: Where were you when we needed Precision entries at contests? Dale is concerned about changes in the Sport Scale event. Actually, the changes he refers to have occurred only in the FAI rules; our AMA rules are not affected.
We have always regarded Sport Scale as just another event, open to everyone regardless of previous experience. This parallels Soaring events, in which the Unlimited sailplane pilot is not forbidden to enter the Two-Meter class. To restrict former Precision Scale modelers to Precision only would banish them from competition. We must live with the fact that Precision Scale, as it was, has diminished.
The addition of visible detail to Sport Scale models has been a gradual change and happened long before Precision died; it's simply the natural progression of quality that has been part of Scale modeling since its beginning. As for Precision modelers taking over the winner's circle in Sport Scale, careful examination shows that consistent winners often have experience in the Pattern event. We distinctly remember that this was a sore point when Sport Scale was introduced. It remains good advice to polish flying skills for Scale events by entering Pattern contests.
Stratification within an event is inevitable, and this is why we have Expert and Sportsman divisions in Sport Scale. It provides an outlet for less-experienced competitors. The real problem, as we see it, is that many of our winners in Sportsman class who are forced upward into Expert elect to drop out when faced with stiffer competition. This also happens in Pattern. The turnover is too great; we don't retain enough of the capable newcomers.
NEW PAINTS
In the past we have mentioned burnishing metallic dope to produce a metal-like appearance. Now there is a complete line of special paints in 17 shades intended for burnishing to duplicate the appearance of aluminum plate, steel, magnesium, titanium, gun metal, exhaust, gold, copper, brass and burnt metal. These are useful for dummy engines, guns, jet aircraft exhaust areas, landing gears and other metal surfaces. The amount of buffing determines the degree of gloss obtained: aluminum plate finish, for example, can range from dull aluminum (not buffed) to an almost mirror finish when buffed with a soft cloth. The paint is called Metalizer and is available from Metalizer Products, 1019 Bonita St., Tustin, CA 92680.
NEW COVERING
Coverite is marketing a new metal-like Micafilm material with a coating that closely simulates the appearance of bare aluminum. The material, in 29 in. by 65 in. sheets, gives another means of achieving a metallic color and gloss representative of many aircraft. Micafilm isn't mirror-like nor does it attempt to simulate chrome plating; it has the look of rolled aluminum. For a polished surface it would need a coating of Coverite Glaskote or clear epoxy.
COLOR DOCUMENTATION PHOTOS
One of the most frequent requests is for documentation photos in color. Dale Willoughby has added another 14 aircraft to his listing of color photo packs, bringing his total to 465. All but five of these packs consist of photos taken personally by Dale in his travels. His list contains detailed information about each plane—color, markings and which areas of the plane are covered—and notes portions (some cockpits, for example) that may not be included. His photo pack listing is $1 from Scale Model Research, P.O. Box 685, Orange, CA 92666. For $1 more he will send a computerized list of aircraft in museums in the area you will be visiting; the list gives worldwide coverage.
NEW SCALE PUBLICATION
Model and Allied Publications of England has produced another of its series of specials, Radio Control Scale Aircraft. Each of these issues is equivalent to a whole year of our Scale columns. In addition to full-size plans for a Chance Vought Cutlass and a Bellanca Skyrocket, the book contains data on Scale Rallies in Canada, Sweden, Australia and Old Warden in England. How-to information includes Suitcase Scale, engines for Scale, flaps, researching, structural integrity, auxiliary controls, cockpits, Scale gliders, kit building, Scale detailing, and descriptions of the flight of some commonly modeled aircraft. Look for the magazine at your hobby shop or bookstore—each of these specials contains a fund of information not easily acquired piecemeal.
Bob and Dolly Wischer S-221 Lapham Peak Rd., Delafield, WI 53018
Transcribed from original scans by AI. Minor OCR errors may remain.
