FLIGHTBASICS
What you’lllearn:First flights can be intimi-dating, but this chaptercontains all of the tips andtechniques you’ll need totake off—and land!—safely.Expert pilots detail hand-launching techniques, howto master control inputswithout leaving the ground,and even how to tame astall. Move on to flat turnsand flying with ailerons, andyou’ll be well on your wayto earning your wings!
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Flight basics30
Get a grip!Hand launching works great, especiallyfor smaller lightweight flyers. In fieldswith tall grass, hand launching is theonly way to go. A certain amount ofcare is required, though, as you arehandling a model whose propeller isspinning. To successfully launch amodel by hand involves more thanjust grabbing it and throwing it towardthe sky. First, with one hand, hold yourmodel firmly just behind its center ofgravity while your other hand holdsyour radio. Hold your model overheadwith its wings level and its nosepointing toward the far end of theflying field. Throw it overhand, andaim its nose at or slightly above thehorizon. Don’t launch the model in asteep, climbing attitude, as it willquickly slow down and may crash ifit stalls shortly after it’s released.
Take a few quick steps and release themodel as your hand and arm just passthe vertical position; follow throughwith a smooth, single arm action.Hold the model off to one side slightlyso that you do not hit yourself with awingtip or the tail. Don’t wind up andside-sling your model as if you’re try-ing to strike out a batter! And don’tlaunch your model underhand as ifyou’re lobbing a lawn dart or heavinga shot put! Think overhand javelin-style or throwing darts at a wall target!
What’s nextAfter you launch, make any requiredadjustments to keep your model’swings level and its nose pointingslightly above the horizon. Let itgain airspeed before you make yourfirst turn.
Hand-launchingbasics—by Gerry Yarrishillustrations by David Baker
With the proper hand-launching technique, your motion is effortless and graceful. When you throw your model,think of it as tossing a dart! Never launch your model underhand.
When we think of airplanes taking off, we usually imagine themrolling down a long runway, lifting off andclimbing skyward. With electric-poweredbackyard flyers, however,we don’t need a long runway. Many do havelanding gear and wheels,but for the most part,they aren’t big enoughto allow the model totake off from grass;instead, they require asmooth, flat surfacesuch as a paved parkinglot. If you fly from afield, as most of us do,there is another way toget your model into theair: hand-launch it!
31Hand-launching basics
If the model zooms upward sharply,add some down-elevator to bring it toa level attitude and prevent it fromstalling. If the model heads toward theground after being launched, add onlya slight amount of up-elevator (apply-ing too much up will slow the modeland cause it to stall).
Hand launching is such a success-ful way to get models airborne thatmany don’t even have landing gear.Landings are usually made with themotor turned off; the model simplylands and slides to a stop on its belly.Almost all electric-powered gliders dothis. The advantages of being able todo without landing gear are simplifiedconstruction and less weight and drag.Less weight and drag mean longerflight times and better performancefor a given amount of power. Handlaunching allows you to fly from areasthat wouldn’t allow operation oflarger, landing-gear-equipped models.If you have a large enough backyardand there’s enough room for a land-ing approach, hand launching andbelly landings offer a perfect way touse the area. After all, it’s the flyingthat counts.
Don’t throw your model like a javelin or heave it likea shot put. To get it airborne, aim it toward the hori-zon, take a few steps and gently release it overhandwith a smooth arm follow-through.
Backyard flyers don’t have to be thrown as if you’re trying tostrike a batter out! Leave your sidewinder pitch at home,and your model will love you for it.
The best way to safely hand-launch a model is to have a friend do it for you.This allows you to hold your radio with both hands and to concentrate on yourmodel. You can do the same for your buddy when it’s his turn to fly. If you dofly by yourself, hold the transmitter off to one side so your model doesn’t hit theantenna. Also, hold in a slight amount of up-elevator while you hold the radio,or add a little up-trim to the controls. Release your model smoothly, and asyou follow through, bring your launching hand to the radio and grab the stickas soon as you can.
The buddy system
Flight basics32
Easysteps tofirst-flightsuccess—by John Reidillustrations by David Baker
OK; you’ve assembledyour plane, balanced itand checked the con-trols. It’s a beautiful daywith hardly any wind,and you can’t wait to getto the baseball fielddown the street andhead for the clouds! Weall know that the bestway to learn how to flyis with someone moreexperienced, but can yoube successful on yourown? This month, we’lltalk about some simplepractice tips for your firstfew flights. Follow thesein sequence, and you’llbecome a backyard acein no time!
Hail a taxiNo; not that kind of taxi! We’re talk-ing about driving the plane on theground. Taxiing slowly gives you afeel for the controls—especially whenthe plane is coming at you, and thecontrols feel reversed. The ruddercontrols ground steering. Notice howmuch throttle it takes to get the planerolling. After a few trips back andforth, speed up a little. Now get theplane right up to takeoff speed (butdon’t take off yet!), and see whetheryou still have complete control. (If the plane does start to take off,keep the sticks where they are, cut thethrottle back to idle and let the planesettle back down to earth.)
If your plane is a tail-dragger (twomain wheels with a small wheel underthe tail), the back of the plane maycome off the ground as the planespeeds up; if this happens, just pullthe elevator stick toward you (that’sup-elevator) to prevent the plane fromtipping over. Even when the tail is inthe air, the rudder controls which waythe plane turns.
Take off OK—whoa, now! I know just whatyou’re thinking: you’ve done yourground-school taxiing, and now, you’reready to tear into the sky. Relax! We’regoing to take baby steps, but you’ll beflying high before you know it.
Begin the takeoff by standingbehind the plane and pointing it intothe wind (however slight it may be).Slowly advance the throttle until theplane moves along the ground at apretty good speed, and gradually addsome up-elevator until the plane startsto take off. Remember; the planeshould have a nice, smooth climb-outinto the sky, so try to keep the stickmovements slow and gentle. As theplane leaves the ground, stop addingup-elevator, and hold that stick posi-tion. Let it climb out until it’s about 20or 30 feet high. Keep the wings levelby using the rudder or aileron sticks.
Now throttle the motor back untilit’s at a slow idle, or it turns off. Ease off on the elevator a little, and letthe plane settle back down to earth.Keep the wing level all the way backdown. Just before the plane touchesdown, add a little up-elevator so theplane doesn’t hit the ground hard(this is called “flaring”). You’ve justcompleted your first flight! Now taxithe plane back toward you, and trythat again. Continue to practice theseshort little flight hops until you feelat ease with the plane in the air.
Making the turn Now that you’ve mastered straight andlevel flight, it’s time to make yourfirst turn. After all, I’m sure you’retired of taxiing all the way back from
Relax! Learning to fly is easy if you follow these simple steps.
Practice taxiing until you’re com-fortable with the controls.
33Easy steps to first-flight success
each of the short flight hops. You’ll doall the same things that you did onthe straight, short flights, only now,you want to keep climbing until youare about 100 to 200 feet above theground. Slowly (notice that I said“slowly”) push the stick to the right orleft, and make a nice, easy turn. Whenthe wing banks (that is, one wingtipis higher than the other) to about 10
or 20 degrees above level, hold thestick there. As the plane flies throughthe turn, it starts to drop and losealtitude. Gently pull back on the elevator stick, and feed in a little up-elevator to keep the plane levelthroughout the turn. When the planehas completed the turn and is head-ing back toward you, return the sticksto the neutral position; the planeshould level out. If the plane contin-ues in the turn after the stick iscentered, slowly add in the oppositestick until the wing is level, and thencenter the stick again.
Congratulations! You’ve just madeyour first turn, and it wasn’t so hard.After the plane flies by, make the sameturn at the opposite end of the field.Continue to practice the same turn,making big, level ovals in the sky untilyou have to land the plane. Calm down
while the battery is charging, then slapit back into the plane and head forthe sky. This time, do the oval in theopposite direction.
At the end of the day, when every-thing has been turned off, take a lookaround, and stand tall and proud:you are the new backyard ace of theneighborhood. Take that plane home,and enjoy your accomplishment.
Continue to practice turns and levelflight on your next flying adventure. As your confidence grows, do somefigure-8s (left turn, then right turn);loops (full up-elevator until the planemakes a full vertical circle in the sky);and rolls (full right or left until the planerolls over completely and is in level flightagain). Just make sure that you haveplenty of altitude when you try newmaneuvers; that way, you can recoverto level flight if you get disoriented.
Maybe your flying field has tall grassthat won’t allow the landing gear tomove freely for a ground takeoff,or your plane doesn’t have landinggear. How do you get your planeinto the air? You use the samemethod as the Navy uses to get itsfighter aircraft into the sky! Of course,you won’t be using a steam catapultto hurl the plane into the air at amillion mph (OK; I’m exaggeratinga bit here). No; you’ll just use yourhand to give the plane a gentle,level toss into the sky.
Hand-launching works great—especially for smaller, lighter flyers.You’ll need to be careful, as you arehandling a model with a spinningpropeller. The proper technique isto hold the model firmly just behindthe center of gravity while you holdyour radio with your other hand.Face into the wind, and start themotor. Keep the wings level, and aimthe nose slightly above the horizon.Give it a smooth, gentle toss, as if youwere throwing a dart at a target ona wall. Don’t launch the plane in asteep, climbing attitude; it will quicklyslow down and will possibly stall.
After the plane has been launched,bring your hand back to the controlsand input any adjustments you mayneed to keep the wing level (remem-ber—slow and gentle stick controls).Let the plane fly out in a level flightand gather some airspeed before itclimbs and gains altitude. There youare; your model is airborne, and youdidn’t even need a runway.
Hand-launchtechnique
Practice turning in one direction, making big, level ovals in the sky.
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1. Never slam the sticks to the extreme ends of their move-ment. Always—always—make easy and smooth stickmovements. In RC flying, slow and smooth is much bet-ter than fast and hard.
2. Whenever possible, fly over grass. That way, if the planemakes an occasional “rough” landing, it will hit some-thing that’s semisoft. Think of it this way: if you trippedand fell, would you rather it be on grass or concrete?
3. Make sure that you have plenty of room to fly your plane.Fly it in a field that seems way too big for your tiny planebecause even small planes eat up a lot of sky oncethey’re airborne. Give yourself more room than you need.
4. If you can afford to, bring along an extra battery or twofor your plane. The extra juice will mean that you cancontinue to fly while the battery you just used up isrecharging. Maximizing flight time at the field will quicklyimprove your flying skills.
5. Don’t fly where someone else is already flying, unless youknow which frequency the other flier is using. If anotherflier turns on a transmitter with the same frequency asyou are using, your plane will crash. Be aware of whatother people are doing.
6. Don’t fly on windy days. If you can feel the wind in yourhair, it’s probably too windy to fly; save your plane andyour flight plans for another day.
7. Balance the plane according to the instructions. Someready-to-fly planes are balanced at the factory, but if yourinstructions recommend that you balance the plane, youshould do it.
8. Fly at home. There are many good flight simulators onthe market today; invest in one. They can give you a feelfor how an RC plane flies. It’s better to crash many vir-tual planes than one real one. Besides, who doesn’tenjoy a good video game?
9. Make sure that the control surfaces move in the rightdirections. Believe me, when you move the stick to theright, you will want the plane to go to the right. If youaren’t sure in which direction the surfaces should move,have the plane checked out at your hobby shop.
10. Wear sunglasses. The first time you watch your plane flyinto the sun and your eyes tear up from the intenselight, you’ll understand why this flying accessory isessential. The cool factor is important, too!
Top10 tips for a successful flight
Flight basics
Pilot debriefingTo be successful on your own, you musttake each step slowly and practice,practice, practice. Never slam thesticks around; gradually move themin the direction you want to go. The plane’s nose shouldn’t continu-ally point up for long periods; the planewill slow down and stall (because thereisn’t enough air flowing over the wingto keep it flying). To prevent thisfrom happening, fly the plane levelmost of the time, and do shallowclimbs and dives. These tips shouldget you through the first couple offlights and on your way to becomingthe number-one ace on your block.
Never slam the sticks;easy, smooth stick correc-tions are the way to go.
35Slip & slide with flat turns
One such maneuver is the flat turn(turning the airplane without bankingits wing). This involves yawing theplane through 360 degrees using therudder, ailerons and elevator to keepthe plane perfectly flat and with itswing level. Although this sounds easy,it takes a lot of practice to use all ofthe model’s controls simultaneouslyto properly execute the maneuver.But when you’ve mastered this move,all of your flying buddies will wonderhow on earth you did it.
Model requirementsWhether you’re able to successfullydo flat turns will depend largely onyour aircraft’s design. Almost any typeof model can do flat turns; it can havea high or a low wing, or the wing can be in the middle of the fuselage.The main requirement is that it musthave ailerons, a rudder and elevator.Also the less dihedral the model has,the easier it will be to do the maneu-ver (dihedral induces roll when rudderis applied).
At the fieldBefore you try a flat turn for the firsttime, there are a couple of things tobe aware of: a flat turn requires a lot
of rudder throw, and this creates a lotof drag. While applying lots of rudder,be careful that the plane doesn’t slowdown too much, or it might stall and crash.
Let’s do some 180-degree turns firstto see how the plane reacts to largerudder inputs. Start by establishing astraight flight path parallel to theflightline and at a safe altitude. Setthe throttle to about 1⁄2 or slightlymore. Just as the airplane gets rightin front of you, use only the rudder(start slowly and use about 1⁄2 rudder)to turn the airplane away from theflightline and observe what it does.The airplane will start to do threethings at once: yaw, roll and lose altitude. To keep its wing level, you’llneed to apply opposite aileron andup-elevator to prevent the plane fromlosing altitude. If you used left rudder,apply right aileron and move theaileron stick just enough to keep thewing level. Also add throttle as neces-sary so that the plane maintains itsaltitude. The rolling motion thatoccurs as you apply rudder is called“roll coupling,” and just about everymodel exhibits this trait.
When the aircraft has turned 180degrees, return the sticks to neutral
Slip &slide withflat turns
Now that you’ve prac-ticed flying your model,you’ve probably donebasic aerobatics such asloops and rolls and areready to try somethingreally different. Thoughlooping and rolling anairplane can be excitingand challenging, thereare other maneuvers thatare more challenging andare very impressive whenperformed correctly.
Combinations of upright and inverted flat turns are the foundations for more complicated maneuvers.
During a left flat turn,apply left rudder, right aileron
(to keep the wing level) and up-elevator to keep
from losing altitude.
ff
—by Rick Bellillustrations by Richard Thompson
& FX Models
Flight basics36
and fly straight and level. You shouldnow be flying in the opposite direc-tion from where you started themaneuver. Practice this a few times,and be sure to do it from left to rightand right to left, as the plane willmore than likely react differently inboth directions. Just remember thatflat turns are high-drag maneuvers;after all, you are forcing the airplaneto fly sideways. Also, there is lesstotal wing lift because in a flat turn,the inside wing is actually moving ata slower airspeed than the outsidewing, and less lift means that youcould stall the wing. If you do stall it,neutralize the elevator, rudder andailerons; increase the throttle a little;and let the nose drop slightly. As yourplane regains airspeed, apply a littleup-elevator, and you will have fullcontrol again.
Maneuver variationsOK; let’s get to the really interestingstuff. Now that you can do 180-degreeflat turns, try a full-circle flat turn.Start the maneuver as before, and adjust
the ailerons, elevator and throttle tokeep the plane perfectly flat and level.
Remember to compensate for anywind as you fly the circle; the planewill tend to drop slightly going down-wind and then rise slightly as it fliesinto the wind. As before, do left andright and circles.
Now combine the left and right cir-cles and do a figure-8. This will reallytest your piloting skills! After you’vecompleted a full circle, very quicklyapply opposite rudder and aileron tostart the second half of the maneuver.It isn’t easy to do it so that the transi-tion from one circle to the next is
smooth and seamless; it takes a lot ofpractice. But you’re having fun, right?This maneuver looks exceptionallygood down on the deck.
Another variation is to do flat turnsas you fly inverted. To do a left-handcircle, use right rudder, left aileron anddown-elevator. Of course, the oppositeis true for a right-hand circle. Doingcircles and figure-8s is very challeng-ing but rewarding. Combinations of upright and inverted flat turns are the foundations for more compli-cated maneuvers. Master them, and you’ll be well on your way tobecoming a backyard ace!
f fUse left rudder, right aileronand up-elevator during thefirst circle of a figure-8.
As soon as the first circle iscomplete, quickly apply rightrudder and left aileron tocomplete the second circle.Don’t forget to use elevatorto maintain altitude.
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2
ff
37Quit stalling!
Angle of attackThe angle of attack (AoA) measureshow much a line, drawn from theleading edge to the trailing edge of aflying surface, is not aligned with thedirection of the oncoming wind. At avery small AoA, a wing may provideonly a small amount of lift. As youincrease this angle, however, the wingprovides more and more lift. Increasethe angle and you increase the lift,but at a certain point, the AoA stopsproducing more lift and instead startsto add drag. This happens ratherabruptly for some wings; for others,the transition is gradual.
If you continue to increase theAoA past this point, the wing’s abilityto produce lift is severely diminished,and it stalls. When we say that awing has “stalled,” we mean that itsAoA has increased to a point atwhich the wing produces little or nolift and lots of drag. Without lift,gravity causes the plane to head forthe nearest planet: Earth.
Stall controlYou can change the AoA of the wingof a typical 3- or 4-channel modelplane in only one way: by operatingthe elevator. Stalls are always causedby the pilot’s pulling back on thetransmitter stick! Always!
Let’s look at the stall that can happen when you are landing. Theplane is close to the ground, and youhave throttled back or are perhapsgliding in. As a plane slows, the wing
develops less lift. So to go still slower,you gradually pull back on the stickto increase the AoA. This increasesthe lift of the wing to compensate forthe loss of lift caused by flying moreslowly. If you overdo it (that is, if youpull back too far on the stick), theAoA will get too high, the wing willstall, and the plane will fall.
Stalls can occur when you are in aturn, too. A conventional airplane turnsby banking (with the rudder or ailerons,depending on the model), and then bythe pilot’s pulling back on the stick tomake the plane go around the turn.
Did you catch the key phrase? It’s“… by the pilot’s pulling back on thestick.” If you pull too far, the planewill stall. This can happen at any speed.If you have enough elevator authorityand if you pull back far enough, youcan stall the plane. Many trainershave tiny elevators to help minimizethe chance of stalling inadvertently,but these planes can still be stalled.
A third kind of inadvertent stallsometimes happens at the bottom of aloop, when you are trying to pull out.The plane is going very fast, straightdown, and you pull back on the stick.If you pull back too far and if there issufficient elevator authority, you willstall even though the aircraft may begoing as fast as it can.
To summarize: whatever its speed,a plane stalls whenever too much elevator is used. This is true for invertedflight also, but in that case, you’vepushed too far forward on the stick.
Quitstalling!
—by Jef Raskinillustrations by Clarence Porter
People who are unfamil-iar with flying think thatan airplane is said to“stall” when the engineunexpectedly quits. But aswe fliers know, that isn’tright. Even a glider (whichdoesn’t have an engine)can stall in the sense thatpilots use the term. It isimportant to understandstalling because unin-tended stalls can cause acrash. But some aerobaticmaneuvers require stalling!Just what causes stalls andhow to avoid—and use—them is sometimes apuzzle, even to pilots.
A common—but mis-leading–explanation ofstalling is that a planestalls when it tries to flytoo slowly. But that isn’tthe whole story; a planecan stall at any speed! I’ll explain.
Master the stall, and you’ll be better equipped to prevent your plane from crashing.
Flight basics38
Getting out of a stallIf you are high enough and if the planeis trimmed well, just letting the stickgo for a second or two will usuallysolve the problem. Removing theexcess elevator removes the cause ofthe stall, and with enough altitude,the plane resumes non-stalled flight,and you can use the controls to get itstraight and level. Adding power willspeed stall recovery.
Some planes just drop their nosewhen the wing stalls; this is the easiestkind of stall to cure. With other planes,both one wing and the nose drop,and the plane enters a spin. Releasingthe elevator usually turns the spin intoa dive, and you can gradually pull upinto level flight. Sometimes, releasingthe elevator and using opposite rudderis required. It depends on the design ofthe airplane and where it is balanced.The farther back a plane is balanced,the more aggressive its stalling behavior.
Aerobatics with stallsIn snap rolls, you deliberately stall onlyone wing half. The other half is stilllifting, so the plane rolls very quickly.In a snap roll, you usually start withfull up-elevator and also apply rudder.The up-elevator brings the wing near tothe AoA at which it will stall, and sud-
denly applying rudder makes one wingstall while the other is still flying. Theplane makes an incredibly fast, gyrat-ing roll. Not every airplane does asnap roll in quite the same way; someneed a bit of aileron to get it going,others can hardly snap at all. Somerequire elevator application ahead ofrudder, and so forth. That’s why it’s anadvanced maneuver. Also, unless youstart it heading upward somewhat,your plane will lose altitude.
Planes with strongly tapered wingsare usually easier to snap-roll thanplanes with less tapered or untaperedwings. A lot of washout (where thewingtips are twisted to have a lowerAoA than the wing roots) can helpprevent snap rolls. That’s why goodfirst airplanes often have rectangularplanform wings and some washout.
Stall recovery101One of the hardest things to learn whenyou see a stall starting on a straight-ahead landing is that you should pushon the elevator stick. This is difficultbecause all your instincts tell you to pullup! But to save the plane, you need alower AoA, and you can get that onlywith some down-elevator. This takes alot of practice, which is most safelyobtained by practicing stalls and stallrecovery high up in the air. Get to know
what a stall-about-to-happen looks likeand just how much elevator has to beapplied to kill the stall before the stallkills the model.
I have seen many fliers crash byunintentionally doing a snap roll whenthey turned onto final for landing.They are trying to go slowly, so theyhave input a lot of up-elevator, andthen they use the rudder to make thatlast turn. But that’s exactly what youare taught to do to start a snap roll!Suddenly, and without enough alti-tude to recover, the plane does a snaproll into the ground. I ruined a fewmodels that way myself before Ilearned the key facts about stalls:
• On a conventional plane, stalls arealways caused by the overuse of theelevator and can happen at any speed.
• The use of rudder or aileronwhile holding up-elevator can causeone wing to stall, and the plane maystart a snap roll.
• The times when you may beholding too much up-elevator with-out realizing that you are doing soare when landing, when makingsharp turns and when pulling up athigh speed.
These are the times when stalls usu-ally get pilots into trouble. The defenseagainst unwanted stalls? Understand-ing why and how they happen.
Rectangular wings (left) are lessprone to sudden stalls than taperedwings (right).
A wing will stall when its AoA reaches a certain angle relative to its direction of flight. Several factors can affect this angle; when the wing is stalled, it produces little, if any, lift and lots of drag.
AoA AoA AoA AoA
Straight flight Increased liftLess lift/more drag
No lift/lots of drag
39Fun in the wind
Back in grade school, we learned aboutsolar energy and how it affects theweather by heating and cooling theground. Hot air rises, and cool airsinks. This is basically where windcomes from. High- and low-pressurezones drive the wind from one placeto another. But enough of the boringscience stuff.
Stay calmIt is really easy to “read” the wind;just look outside and see whether the leaves on the trees are still or arewaving about. Flags atop tall flagpolesare another good wind-speed indica-tor. If a flag is waving at 90 degrees tothe pole, it’s probably best to stayindoors and wait for a calmer day.Because the air is calmest early in themorning and late in the afternoon orearly evening, try to arrange yourflying to take advantage of these conditions. And whatever the winddirection may be, always launch andland your model into it! With all slow-flying models, calmer conditions arealways preferable.
TurbulenceTurbulence (rough air) is a sneakycondition that seems to pop out ofnowhere; it can greatly affect yourmodel’s flight path. When wind flowsaround an obstacle such as a hill, a tree, or a building, it swirls aroundand creates updrafts and down cur-rents. If you fly near or over trees,you’ll immediately see its effects asyour model flies into and out of therough air. To avoid turbulence whenthe wind is blowing, stay away fromtrees, or at least fly several feet aboveor below their tops. Flying too closeto trees often leads to loss of controland can cause your model to get stuckon a stray branch several feet abovethe ground! Buildings and structures
Fun in thewind—by Gerry Yarrish
illustrations by David Baker
When we go out to flywith backyard flyers, one of the variables wehave to take into accountis the wind, and there’smore to think about thanjust air velocity. We musttake into account factorssuch as rising air currents,sudden gusts and unpre-dictable turbulence as well.Though we can’t controlthese, we can learn whereto find them and how toavoid them when they popup! Let’s take a closer lookat the ways of the wind!
Besides enjoying a great view, you can also benefit from rising air currents when you fly from a hilltop!
Catching a thermal will lengthen your flight times.
Flight basics40
also generate turbulence. It’s never agood idea to fly close to or over build-ings anyway, so avoid doing thiswhenever you can. If you fly at abaseball field, anticipate the rough airaround those tall chain-link backstops.You don’t have to avoid large struc-tures altogether; just make a mentalnote of where they are, and be readyto correct your model’s flight path ifyou encounter those invisible bumpsand swirls.
Thermals and rising air currentsRising air currents are generatedwhen the sun heats the ground.Darker patches of ground, such aspaved parking lots and plowed farmfields, heat up more quickly thanlighter areas and generate rising aircurrents known as thermals. Thermals,however, aren’t necessarily bad.
Many modelers search for thermalsand use them to their advantage. You “catch a thermal” when yourmodel flies into a column of rising air and is carried upward by it. Flight times are greatly extended, and you can conserve your batterypower. But watch out! Your model canbe carried to such an altitude that it’svery difficult to see; a flyaway is areal possibility if it gets too high.
When the wind blows perpendicu-lar to a steep ridge, a cliff, or ahilltop, the upwelling air currentsproduce usable lift. This free liftingforce is what makes slope soaringpossible. You don’t need a very highhill or ridge—just a sustained wind.Some modelers have even used theslope effect around highway over-passes to fly their models, so youdon’t really need to be near an ocean breeze.
Don’t let a little wind stop youfrom enjoying your model. Readingthe wind and adjusting your flightpath are very easy if you know whatto look for. Simply by understandingfrom which direction the wind isblowing and adjusting your model’sflight path accordingly, you’ll maxi-mize your backyard-flying fun.
Avoid turbulence near tree lines.
41Flying wing basics
Flying wings are especially advanta-geous for electric pilots; a sleek wingwith a simple Speed 400 motor caneasily reach speeds of 60mph or more.Flying wings are more durable thanconventional planes. Since most aremade of foam and have rear-mountedmotors, very little, if any, damage issustained during a mishap. Let’s takea closer look at the hows and whys offlying wings.
What happens without a tail?Flying wings come in many configura-tions, but three basic designs are mostpopular: the plank, the sweptback andthe delta (the sweptback-wing designis the most common). So, what makesa flying wing fly?
If you removed your model’s fuse-lage and tail from behind the wingand then simply threw the wing,what would happen? Correct! It wouldjust nose-dive into the ground. Why won’t the wing fly? It flewbefore, right? Not really. Three forcesact on every airfoil: lift, weight (verti-cal components) and drag (horizontalcomponent). If the lift and weightwere placed on the same spot, the air-foil would be stable and would flywithout needing a fuselage and ahorizontal stabilizer. But most airfoilsaren’t stable; the lift of most wings is behind the center of gravity (CG),and this creates a turning momentthat causes the wing to nose-dive.This is where the fuselage and stabi-lizer come into play. The aft part ofthe fuselage is a long arm that places
the stabilizer at a distance behind the wing. The stabilizer creates adownforce and counters the turn-ing moment of the wing; hence, stable flight.
A flying wing, on the other hand,doesn’t have a fuselage and horizon-tal stabilizer to create the necessarydownforce, so the stability must bedesigned into the wing itself. One ofthe biggest considerations of a flyingwing is the longitudinal stability andthe location of the CG. On a conven-tional airplane, the horizontal tailand its distance from the wing makeit easy to achieve longitudinal stabil-ity. To achieve longitudinal stabilityon a flying wing, the CG must be for-ward of the lift of the wing. But thiswill result in the wing’s nose-diving,just like a plane on which the backhalf of the fuselage has been removed.To bring things back into balance,the wing itself needs to supply thebalancing force. This is done withthe shape of the airfoil, the sweepof the wing, or both.
It’s all in the shapeSo how does all of this tie together tomake a wing fly? Everything dependson the shape of the wing. With asweptback wing or a delta wing, airfoils that are symmetrical (thathave the same shape on top and onthe bottom) are the best choice.They tend to reduce the nose-downpitching action, thereby making thewing more stable. Most of thesedesigns also have a slight twist in the wing; this is called washout, and it
Flyingwing
basics—by Rick Bell
The flying wing has beenaround since the early daysof aviation and continuesto intrigue designers andpilots alike. A flying wingdiffers from a conventionalairplane in that it has nofuselage or stabilizer; it con-sists only of a wing. It alsohas some advantages over a“normal” airplane; it’s eas-ier, quicker and cheaper tobuild, and it offers lowerweight and drag for a givenwing area.
Flying wings have a wide flight envelope and are very aerobatic.
Shown, top to bottom, are the three most popular flying-wing configurations for park flyers: plank wing,sweptback wing and delta wing. Each has specialdesign features that allow it to fly like a conven-tional airplane.
Flight basics42
occurs when the trailing edge of thewing is tilted upward at the wingtip.This twist helps prevent the wing fromstalling. The sweep of the wing alsoprovides a tail-moment arm, much thesame as a fuselage with a stabilizer.
On a plank-type wing, a wide-chord,semisymmetrical (more curve on topthan on the bottom) reflex airfoil iscommonly used. In a reflex airfoil,the entire trailing edge of the wingcurls upward; this provides the neces-sary downforce to prevent the wingfrom pitching downward. Most flyingwings are also unstable in the yaw axisand use a vertical fin for stability.Again, the placement of the fin dependson the design of the wing. Generallyspeaking, delta and plank-shaped wingsfly better with a large fin on the center-line of the model. On sweptback wings,fins called winglets placed on thewingtips provide optimum perform-ance. Of course, there are exceptionsto every rule, but that’s what makesexperimenting so much fun.
Flying wing control surfacesBy now, you must be wondering: if there is no horizontal stabilizer,where do the elevators go, and howdo you make the wing go up anddown? They can’t be on the trailingedge of the wing where the ailerons go,can they? On flying wings, the controlsurfaces are called elevons (a combi-nation of elevators and ailerons).They move up and down together aselevators, and they also move inopposite directions to act as ailerons.
To achieve this in a model, controlmixers—either mechanical or elec-tronic—combine the elevator andaileron commands from the transmitterto obtain the correct elevon movement.Electronic mixing, either in the trans-mitter programming or by means of aplug-in mixer between the servos andthe receiver, is the most common andeasiest way to control elevons. Mechan-ical mixing usually involves a slidingservo tray and complicated linkages.
Another way to treat elevons is tosplit them in half. The inboard por-
tions of the control surface act only aselevators, and the outboard sectionsact as ailerons. You usually see thistype of configuration on a delta wing.
Flying a wingAs unconventional as flying wingsare, they do fly quite well. But thereare a few things to keep in mindwhen you fly a tailless model. First,the CG needs to be as far aft as possi-ble yet still maintain longitudinalstability over the pitch axis (elevator).If the CG is too far forward, the wingwill require a lot of upward elevondeflection to fly level, and this willcause unnecessary drag and willdegrade performance.
To turn the wing in flight, you’llneed to use a combination of aileron(to bank the model) and up-elevator(to control the radius of the turn).The more elevator you use, thetighter the turn. As you can imagine,a flying wing can turn very sharply.
It isn’t very difficult to launch aflying wing, despite the absence oflanding gear or a fuselage to grip.One method is to bungee-launch it(much like firing a slingshot). Themost common technique, though, isto hand-launch it. Here’s how: placethe wing on your fingertips with yourthumb grasping the leading edge ofthe wing. Raise the wing over yourhead with your fingertips pointedover your shoulder and, using astraight-arm, overhand motion, taketwo or three steps and then toss themodel; don’t throw it. Release thewing, hit the throttle, and it will beon its way. One note about hand-launching flying wings: because mosthave a rear-mounted motor and pro-peller on the back of the model,never grip the model at the rear, nearthe propeller, or launch it with themotor running; the propeller couldstrike you.
Flying wings are fascinating flyingmachines; they have a wide flightenvelope, are very aerobatic and aredamage resistant, which makes themgreat for beginners. Why not giveone a try? You, too, will say,“Farewell to the fuselage!”
The airfoil used for a flying wing plays an important role in determining its flight performance. A semisymmetri-cal airfoil that is reflexed (top) is widely used on plank-type wings. Sweptback and delta wings use asymmetrical airfoil (bottom) with washout on the tips to provide the necessary downforce.
Reflex
Weight
Weight
Balancingforce
Balancingforce
Lift
Center of gravity
Center of gravity
Aerodynamic center–neutral point
Tail-moment arm
Tail-moment arm
Washout
<
<
>
>
<
Lift
The control surfaces on a flying wing are called elevons. They work together as ailerons and elevators to con-trol the pitch and roll of a flying wing. Transmitter programming or an electronic mixer plugged in between theservos and receiver synchronizes their movements.
Elevatormovementfor pitch
Aileronmovementfor roll
43Easy fun-fly maneuvers
Fun-Fly ChallengeBasic fun-fly maneuvers and missionscan be very simple: you competeagainst the clock to do specific maneu-vers, increase the precision in whichyou execute your flights and add acertain degree of chance to enhancethe fun factor. Here’s a breakdown ofstuff I enjoy.
Timed flightThis is perhaps the easiest form offun-fly competition. Just get a bunchof your friends together and use astopwatch to time everyone’s flight.Pick a specific flight duration (2 min-utes, for example); the time beginswhen the model leaves the ground(or leaves your hand, if you hand-launch), and it stops when you land.The one who is closest to exactly 2 minutes wins! Oh, yeah; no othertiming devices are allowed! Just countoff in your head—one Mississippi,two Mississippi, three—until you think2 minutes are up. Allow yourself about20 seconds to set up a final approach,and try to land exactly at the 2-minutemark. Try it! It isn’t as easy as it sounds!
Timed maneuvers These are well suited to beginnersbecause they don’t require takeoff andlanding skills. The maneuvers can alsobe done with an instructor or helperstanding close by. You first determinethe maneuver to be flown: three ormore loops, three or more rolls, etc.;then, from straight and level flight,you call the start. The pilot performs
the maneuvers and returns to levelflight. Everything is done at a safealtitude, and the shortest time wins.You can also try inverted flight inwhich the longest time determinesthe winner.
Touch-and-go’sTypically, you run this event eithertimed or with a specific number ofpasses. For more experienced fliers,set the timer for 3 minutes to make asmany touch-and-go’s as they can in theallotted time. Allow less experiencedfliers 5 or 10 passes, and let them landand take off on each pass. Of course,you need a smooth flying field toallow proper touch-and-go’s.
Spot landingsYou’ll increase your precision as youtry to land either in a chalked circle(10 or 20 feet in diameter) or close toa straight line drawn across the run-way. This also is good for flying fieldswhere touch-and-go’s may not bepossible. The pilot launches his modeland then sets up for a landing in thecircle, or as close to the line as he can.Allow each pilot three to five attempts,and count the number of times themodel touches the ground. The circlecan be a bull’s-eye with two or threecircles, and you can assign points foreach circle: 1 point for simply land-ing anywhere on the flying fieldwithout breaking the model, 5 pointsfor landing in the outer circle and 10points for the inner circle. This can
Easy fun-fly
maneuvers—by Gerry Yarrish
illustrations by David Baker
Once you are bitten bythe RC bug, it doesn’ttake long before youstart looking for moreexciting challenges to dowith your backyard flyer.Just flying around in cir-cles is not as much funas accomplishing a flightmission. Flying specificmaneuvers allows you toacquire a higher degreeof skill and, as far as I amconcerned, adds greatlyto the fun. No, I’m nottalking about precisionaerobatics, though somedesigns are now capableof such performance; I’m talking about back-yard barnstorming andsimple fun-fly maneu-vers. Once you try them,you’ll look for others tojoin in and have a littlefriendly competition.
Timed maneuvers are a great way to add a competitive elementto your flying.
Flight basics44
also be a timed event in which thepilot makes as many attempts as pos-sible in the given time limit. The mostpoints determines the overall winner.
Slow-speed raceThis will test the pilot’s skill at flyingslowly from one point to another. Set up a straight course with a flagmanpositioned at the beginning and theend of the course. The pilot then fliesinto the course and adds up-elevatorand reduces power to slow the modeldown. When he enters the course,the first flagman signals to start thetimer, and the pilot then flies astraight course to the other flagman,who then signals the end of theflight. To keep the competition fair,no one is allowed to do S-turns orhover his model; it must maintainstraight, controlled forward flight.The longest lap time wins.
Dice rollsThis is strictly a chance event andrequires the modeler to take off andthen roll dice in a box. The pilot canhave a friend roll the dice. The mod-eler is then timed, as the helper rollsthe dice, until he rolls the same num-ber as the first throw. The pilot thenlands the model, and the timer isstopped. The shortest time deter-mines the winner.
All up — last downThis event is also timed and may includeas many pilots as you can accommodatewith the radio frequencies you have.Everyone lines up and launches theirairplanes at the same time. After a 1- or2-minute motor run, everyone throttlesback to turn power off. As the modelsglide back to the ground, the last oneto land wins. If you have a conflictwith radio channels, two or morepilots can fly at different times with astopwatch measuring the flight time,and the longest flight duration wins.
These are only some of the manyfun-fly events that you and yourfriends can try to add fun andexcitement to your backyard flying.You can also make up your own special events: place a Styrofoam cup on the runway and try to hit it;stretch toilet paper between twopoles and do some limbo passes, ortry to cut the paper. Anything goes,as long as you do it safely. Give it a try; everyone wants to be a back-yard barnstormer!
A spot landing tests your ability toprecisely control your model.
All-up, last-down events allow many pilots to compete at the same time.
45Ailerons: the next step
Unlike models that only have rudderand elevator control, where banking isa byproduct of deflecting the rudder,ailerons make one wing panel imme-diately go up and the other go down.You can bank a model that hasailerons much more quickly than onethat does not, and this means thatyou can make the aileron-equippedmodel do a roll just by pushing theright transmitter stick fully over toone side and returning it to centerafter the model has come back to itsupright position. It’s easy and fun.
You can also fly inverted (upside-down) much more easily with anaileron-equipped model because theailerons work in the same directionwhen inverted as when in uprightflight. Once you roll the plane upside-down, you slightly push forward onthe elevator stick to hold up the noseof the plane. Most planes will now stayinverted. With some practice, you canfly turns and circles while inverted.
The simplest aileron-equippedmodels have three controls: aileron,elevator and motor speed; truly aero-
Ailerons: thenext step
—by Jef Raskinillustrations by David Baker
Many basic backyard flyersare flown with just rudder,elevator and motor speedcontrols. These models aregreat for learning to fly andfor having fun, but addingaileron control greatlyincreases your flyingoptions—especially whenit comes to aerobatics.
n Before you attach your aileronservo’s control arm and aileronpushrod linkages, be sure to turnyour transmitter and receiver onand center the servo.
n Mechanically adjust your model’slinkages so that your ailerons areperfectly centered at neutral and thatthey move the distance recomendedby the model manufacturer.
n When you stand behind the model(facing the tail) and move theaileron transmitter stick to theright, the right aileron should moveup, and the left aileron should godown the same amount.
n Before flight, always check to be surethat none of your model’s control sur-faces are binding and that they movein the right direction.
Aileron setup tips
Flight basics46
batic models have a combination ofrudder, aileron, elevator and motorspeed control—called a “full-house”setup. You can learn a lot of aerobat-ics with just aileron, elevator andmotor control. But for some moreadvanced aerobatic maneuvers suchas knife-edge flight and slow rolls, tosay nothing of being able to steer eas-ily on the ground, you also need aseparate rudder control. If the planeis properly designed for aerobatics,using rudder yaws the plane, anglingthe nose to one side without causingthe airplane to bank or turn. Theplane flies a bit sideways.
Aileron rollsStart out straight and level, at fullthrottle. Pull the nose up slightly,release elevator and immediatelyapply aileron. As the plane gets tothe position where its wings are ver-tical (knife-edge), they can’t providelift in the vertical direction, so the
plane will fall a bit; that’s why weaimed the plane upward a tiny bit atthe beginning. The overall impres-sion is that the plane has stayed atone altitude throughout the roll. Asthe plane nears the inverted posi-tion, give a small push on theelevator stick (down-elevator) so thatthe nose doesn’t fall, then release theelevator. As the plane comes uprightagain, center the aileron stick. Nowfly straight and level to finish off themaneuver cleanly.
It takes some practice to get thetiming right and to know just how
much you have to push the elevatorstick so that the plane doesn’t bal-loon up or sag down inverted.
ConclusionWith ailerons, the sky’s the limit; you can do hundreds of maneuvers.Ailerons give more positive control ofbank, allow control when the modelis inverted and speed the roll rate.When you have mastered takeoffsand landings and can fly with someconfidence, make your next modelone with aileron and rudder controland step up to full-house park flying.
The most common way to operate ailerons with aservo is to use both sides of the arm. As the servorotates, one aileron is pulled up, and the other ispushed down.
The model always rolls toward thewing panel with the raised aileron.
1. Entry. 2. Pull nose up slightly and addright aileron. 3. Continue right aileron, and add a little down-elevator. 4. Release down-elevator, and add a little up-elevator. 5. Exitstraight and level.
1
2
3
4
5
Elevator roll
