Guelph Gremlins Model Flying Club

Instructor's Corner

By Craig Skinner, 2001

This article is aimed both at the student pilots and those of us wanting a spring review. The instructors have put together a list of pointers about learning to fly and other useful tricks of the trade.

Yes, We Have Instructors

Newcomers to the hobby sometimes have trouble finding an instructor. Here's the situation: Most mornings and evenings when the weather is suitable you can find one or more instructors at the field. Go prepared to fly. Some instructors will accept phone calls in advance to arrange sessions, but most do not, so don't be disappointed if you don't have one person exclusively. Have your plane in flying condition to the best of your ability. Try to avoid wasting your instructors time having to balance your plane, check your batteries or adjust linkage; arrange to have that done some time before going to the field (Ask an experienced modeller to help you). Before each flying session make sure that your tutor is aware of your progress so far and any problems that you are having. Good Luck.

Check it Out!!!

Make the most of your tutors time by having your plane prepared before you go to the field. If you are just starting out it's a good idea to have an experienced R/Cer look over your plane and equipment. This person doesn't have to be an instructor; most members are glad to spend an hour or so going over your plane at home to make sure balance is ok, alignment is accurate, servos are secure, pushrods are not sloppy, engine bolts are tight, etc. There are dozens of items that can be missed by a beginner, and going to the field without correcting them will take time away from your flying…and the flying time of your instructor.

Trees? What Trees?

A brisk breeze across the field (that is, from the road toward the tree line) provides a challenge in two ways. You can take off and land down the field cross-wind, OR use the wind to shorten your approach and come in from the trees toward the road.
If the wind is brisk your final approach can be drastically shortened, perhaps up to 50%, so that you come in on a steeper line - that is you can turn your base lag far short of the trees and do your final approach with your normal air speed but, of course, less ground speed. Also, with a lower ground speed, you can land successfully on a shorter runway (i.e. cross-field). Give it a try.

The Famous Flame-out!!!

The most common cause of engine failure after several minutes of flight is too lean a mixture. After adjusting your carburetor setting by pointing the nose upward, if you are still unsure of your engine's reliability, here's a tip.
Do most of your flying at the downwind end of the field and high enough so that in the event of a flame-out you can land on the field. You can then make further adjustments and fly again at the downwind end until you are satisfied your engine is reliable. You'll avoid a lot of bruises.

To Turn Or Not To Turn!!

"If your engine quits in flight, resist the temptation to turn back to the runway; maintain your direction and land straight ahead". Good advice, but, of course the rule doesn't apply if you have lots of height. Then there are the borderline cases when you are "quite" high but not "real" high…it's a decision you make depending on your experience, and, most important, on the wind. For instance, if you are flying INTO the wind when the engine quits, your chances of a successful turn (without stalling) is not as good as if you had been flying WITH THE WIND.
To illustrate: Let's say your airspeed at the flameout is 40 kph into a 20 kph headwind. If you turn 180 degrees you will immediately cut your airspeed in half…and you might be close to a stall. On the other hand, if you are doing 40 klicks flying downwind and do a 180 INTO the wind you maintain more of your airspeedand are more likely to make the turn safely. But keep in mind, all things being equal, a turn puts you closer to the stall. If in doubt, don't do it.

Is It Squirrely?,

If your plane, on its trimming flight, veers to one side, you can straighten it out by (1) rudder, or (2) aileron. But which one? Ideally, if the fault is caused by a twist in the rudder, one doesn't want to compensate by adjusting ailerons, and vice versa.
To determine where the fault lies, use the fast/slow method. Fly fast and trim ailerons - then slow down and adjust rudder. Repeat this until normal flight is straight. This technique works because rudder is more sensitive than ailerons at low speed.

You Gotta Be Kidding!!!

Want to double-check your balance point (CG) during flight? Here's how. Take your flying beauty to a safe height, fly level, reduce throttle to about ¼, and trim for level flight. Now without changing the throttle setting, push the elevator stick forward and put the plane into a 45 degree (approximate) dive. If the plane pulls up by itself you are nose heavy and if it steepens the dive you are tail heavy. Now some of you have already disagreed with that diagnosis, thinking that it is backward. Not so. You see, when you trimmed the plane for level flight, if it was nose heavy you trimmed in some up elevator to compensate. So during the dive, speed increased, the up elevator became more effective, thus raising the nose.

The Trimming Loop

In previous articles we talked about trimming your trainer (or any other plane) by the fast/slow method. Here's another way to check trim. Do two or three continuous loops. If the plane drifts away to one side correct rudder trim, then fly level and correct any remaining drift with aileron trim. Why does sideways drift with successive loops indicate rudder (and not ailerons) out of trim? Because ailerons will cancel out any drift in a loop-whereas rudder's effect remains on the same side whether upright or inverted. Think about it.

What's the Differential?

Some planes seem to resist a turn into a brisk wind. Since we usually teach aileron turns, we often neglect to stress the importance of rudder, but judicious use of the rudder stick will bring the tail around smartly when aileron aren't doing the job. Use of rudder also makes a "prettier" turn, eliminating the crabbing tendency of some aircraft. Another way to assist turns is to build "differential" into your aileron travel. Simply put, this means that the ailerons travel further upward than downward. The upward aileron thus creates more drag and that drag assists in pulling the plane around. Differential can be accomplished at the control arm or at the servo.

Trim the Trimming Buttons

Let's say you've trimmed your plane so that it flies straight, but your trimming buttons on the transmitter are now off-center. Not the best arrangement and a further adjustment is required on the ground. Before shutting down your receiver and transmitter, note very carefully (and remember) the positions of the control surfaces (rudder, elevator, ailerons). They are now in the "good flying position" as a result of the trimming you have done in the air. Your next move is to move your transmitter trimming buttons to neutral. Of course, that will throw your control surfaces off again, right? So, what you do now is adjust each clevis until each surface is back to its previous (carefully noted) position. Now, before every flight you can make sure the trimming buttons are in neutral and your plane will be trimmed.

Check out the Stall

When starting to fly a new or different plane, check out its stall characteristics. Take it up high, reduce throttle and raise the nose a bit. When it stalls does it keep the wings level or drop off to one side? Does it come to a reasonably slow speed without stalling? If not, you know that you'll have to come in reasonably fast when landing. If you're not satisfied with the results, re-check the CG and inspect the wings for warp. You'll feel more comfortable landing the thing or doing slow fly-pasts if there are no surprises at low speed.

The Days of BBB (before buddy boxes)

You guys who are learning with buddy boxes don't know how lucky you are. When we learned (back in ought-five) crashes were common during training. Nowadays, after a training session you are quite secure in the knowledge that your plane will go home with you. In those "olden days" of BBB there were two very common causes of disaster. They were (1) confusing left and right when the plane was approaching, and (2) nose too high at low speed. Even after, "wings parade" we can still fall victim to those two pitfalls. To avoid the left/right confusion there is no better advice we can give than to repeat the old saying" Point the stick to the low wing". As for not pointing the nose up unless you have sufficient speed, this takes some experience and self-discipline because the obvious urge is to keep the plane away from the ground. All we can say is keep reinforcing the thought that it's a no-no.

Deflate That Balloon.

One of the difficulties to overcome in training is "ballooning". You turn toward the field to land and before you realize it the plane's nose goes up. This ballooning is caused by extra lift when turning into the wind from a cross-wind. The nose-high attitude distracts your attention from all the other adjustments you are trying to make at that time. This can result in a poor approach and an aborted landing. Practice will overcome the tendency to balloon but you can help it along by trying to make your turns flat and steady, by using rudder, and by using a little less up elevator in the final turn.

The Free Fall.

A good exercise to perform at some time during your training is a "free fall". Take your plane up high, point the nose way up, kill the throttle, take your hands off the controls…and watch what happens. The nose will point to the ground, speed will build up, lift will increase and the plane will pull out of the dive…by itself. Well, with some planes you might have to help it a little with some up elevator. The purpose of this exercise is to demonstrate that when you have sufficient height and you panic, just killing the throttle will result in the plane saving itself. Good for your confidence.

The @%$#&*! Engine Won't Start.

Among the frustrating problems for a beginner (and often the rest of us) is starting and tuning a model engine. Some general rules: (1) Open the throttle, cover the carb intake with your thumb, and flip the prop three times, (2) Remove thumb, close, throttle, and flip three more times, (3) Attach igniter to the glow plug and flip to start the engine. You'll be surprised how often the motor will start with that last flip. What happened during this procedure is that #1 pulls fuel from the tank and #2 distributes it into the crankcase. Now for tuning. With the engine running, open the throttle, adjust the needle valve for maximum rpm then point the nose up at least 45 degrees. If rpm's remain steady your ok…if not open the needle valve a few clicks. The next step is to verify the idle mixture. Run the engine at idle for 10 - 15 seconds then open the throttle fully. If the engine quits immediately you probably need to enrich the idle mixture. If it stumbles and sputters but doesn't die immediately the idle mixture is too rich. If it revs up smartly when the throttle is advanced you are in good shape. An improperly set idle mixture can cause a flameout. These are very basic suggestions that may not apply to every situation and every engine, but might be of help.

Check the Buddy Box, Buddy!

Before a flying session you can save the instructor's time and gain his undying approval by checking out your buddy box as well as your plane. After hooking the boxes together, make sure that all control surfaces coincide for both direction and trim. Direction: Turn on the master switch and check that the surfaces on the model move in the right direction when activated by the sticks on both boxes. Trim: Turn the training switch on and off. If the control surface move, then the trim on the slave is out of adjustment with the master. Taking care of this item will get you into the air a lot sooner.

The Lop Sided Dumbbell Circuit.

This circuit allows you to practice both turning in each direction and also an approach in each direction. The wind must be calm or light to do this circuit otherwise you will be coming down the field very fast in one direction. After take-off or a low approach, turn 45 degrees towards the trees, then (and before you reach the trees) turn 225 degrees in the opposite direction back to line up on final approach.

This document and a Realflight airport file of our the Guelph Gremlins Model Flying Club Field are available for download here