Bob Underwood Box 40, St. Peters MO 63376
Newcomers
SOMETIMES MORE is not better! You know: that extra bowling league you joined, five more miles per hour when the radar gun is aimed your direction, the extra yard of topsoil you think you need.
Modeling has the same kind of problems. For instance, when you glue pieces together, a common error is to give it an extra shot of glue to "make it stronger." It usually doesn't. The extra glue adds weight and often makes sanding harder. The trick is to get the adhesive into the joint and make certain the joint is a good wood‑meets‑wood arrangement.
Joints and fitting
Have you seen joints where the modeler attempted to fill the gap with glue rather than cut a piece that actually fits? Cut the piece a little long the first time. No big deal—remember, once you've cut a piece, you can never cut it longer!
Needle valve and engine tuning
We often get into trouble adjusting the needle valve. The instructions included with your engine will give a ballpark figure on how many turns to open the needle valve for starting. This is only a guesstimate; temperature, humidity, fuel, tank placement, and other factors play a role.
The instructions will tell you to turn the needle valve clockwise until it closes all the way—don't force it. Back it out the number of turns suggested, prime or choke the engine, and connect the battery to the glow plug.
Using a starter, a "chicken stick," or other protection for your hands, flip the propeller counterclockwise. When it starts, it should be on the "rich" side—heavy on the fuel/air mix. Once you have properly broken in the engine, you can begin to "lean" it out. Gradually close the needle valve to achieve a proper fuel/air mix.
"More is not better" applies here. The tendency is to lean it out just another notch or two—don't. A lean engine run means a hot engine and ultimately (and quickly) one that's ruined.
As you fly, the fuel level in the tank falls. This results in the engine leaning out during the flight because it must draw fuel from a lower level. You may notice old-timers holding the model with the nose almost vertical as they adjust the needle valve. They're checking to ensure the needle valve is set rich enough so the engine will not "go lean" during the flight.
Fasteners and torque
Another "more is not better" problem occurs when tightening screws, nuts, and bolts—especially on engines. After operating an engine for an hour or so, check that all the fasteners are snug. This includes those holding the head, crankcase cover, carburetor, etc. These often use hex heads, and it's easy to really "put the arm to it." Resist the urge to severely torque them down.
One of three things could happen: you could strip the threads (usually in the engine itself), shear the fastener, or break an engine piece. The latter is common with lug‑type fittings used on rear crankcase covers. Overtightening glow plugs almost always strips the threads in the head rather than the plug. Many wrenches allow quite a bit of pressure because of their design—be careful.
Gaskets, seals, and tightening patterns
If you disassemble the engine, replace the gasket or O‑ring.
First, it costs almost nothing but serves an important purpose. It provides a crushable seat to absorb torque and seals against air passage.
Air leaking into the engine through carburetor throats, crankcase covers, etc., usually results in difficulty adjusting the fuel/air mix and causes a lean run. Some engines do not use a gasket for sealing; they rely on closely machined parts. Many manufacturers provide a pattern or plan for the order of tightening fasteners—especially for cylinder heads. Heed these instructions; ignoring them may warp the head or prevent proper sealing. That costs reliability, compression, and power.
Fuel, oil, and performance
More is not better with the nitromethane content or the oil content of the fuel. A tendency is to think that more nitro will produce "hotter" fuel and more power, or that more oil will create better lubrication. Follow the manufacturer's recommendations.
As with automobiles, compression ratio and other factors affect optimum operation. Increasing performance requires juggling many factors: compression, type of glow plug, propeller size, engine timing and porting, intake size, etc. Changing any one of these can drastically change engine performance.
If you must experiment, change one element at a time and log what you did. It's like achieving the perfect shade of paint only to discover you forgot to record the quantities of the basic colors used.
Control surfaces
More is not better when it comes to control‑surface movement for the newcomer. Most kits and Almost‑Ready‑to‑Fly (ARF) models now include the proper surface movement in their setup instructions. Resist the temptation to think, "If that elevator (or rudder, or aileron) is going to wave at me, let's make it really wave!" If you ignore the suggested amounts and go heavy, you'll have trouble—like Professor Harold Hill's warning in The Music Man: "You've got trouble, right here in River City!"
Quick tips
- Don't overdo the length of those first flights. You're going to be nervous enough without prolonging the agony. Ten minutes is an absolute max—five is probably better. If you go too long, all you do is practice your best mistakes.
- Don't crank up that plastic‑covering iron beyond the recommended heat level, thinking it will make the covering stick better. You'll just learn how to repair the hole you melted in the middle of the wing.
- The nose gear on your tricycle‑gear airplane doesn't have to turn much at all. Too much movement will make your takeoff look like a failed sobriety test in front of the state highway patrol!
Transcribed from original scans by AI. Minor OCR errors may remain.
