Tips, Tricks & How To

Glider Tow Release

by Eric McRae

This month we will highlight a tow release arrangement that has been thoroughly tested and abused and is really very simple to incorporate into your sailplane.  For me, the most important factors for a nose release mechanism are strength, reliability and simplicity.  Most generic sailplanes consist of a solid balsa nose-cone, glued to the front former.  Behind the former is usually where the "guts" of the plane begins. Batteries, servos etc......  The drawings that follow will illustrate one design that will work easily on any solid nosed craft and with some ingenuity the principles can be applied to hollow noses as well as the tail or midsection of the tow plane.

FIGURE 1 SHOWS A TYPICAL SOLID BALSA NOSE-PIECE

Before you start, you should know where the all of your other hardware is going to be placed.  You will later have to route a Sullivan #504 Gold - N - Rod or equivalent from an appropriate spot on former 1 to the release servo.  Begin by marking an exit location on the back side of former 1 and to keep your drill bit from wandering, punch a good sized dimple at the center of the nose cone.  Now for the fun part.  Drill a 3/16" hole from the front of your nose cone to the exit location that you previously marked on the back of the former.  Go ahead and install the outer sleeve of the Gold - N - Rod .  The front of the sleeve should extend just slightly past the front of the nose cone.  It is best if you don't glue the sleeve to the nose block.  If you make a mistake or need to replace it later, it might be a project in itself to remove.  Secure it elsewhere if necessary.

FIGURE 2 SHOWS THE HOLE BEING DRILLED FOR THE GOLD - N - ROD SLEEVE

(My illustration shows a straight shot through the nose.... Your hole will most likely be angled ....Not to worry!)

The next step is to drill the receiver hole that will hold the "ball" until you release it.  The placement of the receiver hole is somewhat dependant on the shape of your nose ( Go ahead, look in the mirror) and the location of the exit hole in the former.  It is best to drill the reciever hole at a downward angle or you may have to rotate the plane in order to set the ball in place.  I would suggest an angle of between 45 and 60 degrees, relative to your sleeve, for a smooth release.  If you are carefull, you can use a standard 1/8" high speed steel bit but I would suggest using a Dremel with a small ball cutter.  If you have to use a drill, start the hole using a piece of brass tube as a drill bit to keep from gouging out the exit hole.  Once you have a good start on it, you can change back to the HSS bit.

FIGURE 3 SHOWS THE RECEIVER HOLE BEING DRILLED AND THE RESULTING CAVITIES

After completing the receiver, file any excess sleeve tubing flush with your nose cone and remove any burrs inside the tubing. Now it's time to install the inner push rod and make the appropriate servo connections.  The pushrod must completely cover the receiver when extended and fully clear the receiver when retracted.  You can use any unused radio channel that suits you.  On a four channel radio controlling a three channel sailplane, I usually use the unused rudder stick for release, but a gear channel or toggled channel works well also.

The only thing left to do now is to rig your tow line with an appropriately sized release ball.  Depending on the size of your release installation you can use many things for the ball.  One of the best things I have found is a stainless steel fishing leader that you can find at Wal-Mart or any place that sells fishing tackle.  I bought a set of 5 or 6 of these for a couple of bucks a few years ago.  You can also use necklace beads as well.  I have even melted the end of my nylon tow line and simply formed a ball.  Whatever you use, make sure that it fits loosly in the receiver and releases smoothly.

Here is how it works!

 
	Fig. 4			Fig. 5			Fig. 6

• Figure 4 shows the inner sleeve fully extended, blocking the ball.
• Figure 5 shows the inner sleeve fully retracted, allowing the ball to exit the receiver.
• Figure 6 shows the ball clear of the nose.  You are now at altitude ready to search for some boomers!

Compatibility Chart

Here is a compatibility chart that may help in selecting compatible finishing / covering materials for your aircraft. Some materials, when applied over others may not cure properly, and or may cause a breakdown in the base materials.

Example 1: You CAN put Epoxy Enamel over Polyester Resin ( Find Epoxy Enamel in the OVER section of the chart and follow the column down to the intersection of Polyester Resin. You will find a "C" which stands for COMPATIBLE.
OR
( Find Polyester Resin in the UNDER section of the chart and follow the row across to the intersection of Epoxy Enamel. You will find a "C" which stands for COMPATIBLE.

Example 2: You CAN NOT put Polyester Resin over Epoxy Enamel ( Find Polyester Resin in the OVER section of the chart and follow the column down to the intersection of Epoxy Enamel. You will find a "N" which stands for NON_COMPATIBLE.
OR
( Find Epoxy Enamel in the UNDER section of the chart and follow the row across to the intersection Polyester Resin. You will find a "N" which stands for NON_COMPATIBLE.

So I've learned how to fly, what now?

( or How to avoid the R/C Doldrums )
by Bob Norvell

In the beginning, there was simply a radio, a box of wood and paper, and you. The wood became a trainer, and soon the shiny new engine will roar to life, converting the precious juice to noise, gooey slime on the trainer, and hopefully some forward thrust. Your heart pounds and your hands shake from the adrenalin rush, you clumsily taxi your labor of love around the field and line up for take-off. A highly recommended instructor puts sufficient air beneath your Sullivan Skylites and hands the radio to you. Straight and level, circles and figure eights. A loop, a roll, and finally after many flights, you take off solo. A few more hops and your ready to land your own ship. Inverted flight, spins and even knife edge, the landmarks sail by. Suddenly the miracle of flight is no miracle after all. You are a competent pilot now and the thrill is all but gone. What can you do to recapture the challenge of R/C flight?

1. Set yourself some goals: Originally, flight itself was your goal. Once you have met your goal,set another one (Not too high, just out of reach). An example for sport flyers could be to perform a slow roll so that you cross a specific point inverted. A beginning pilot might set a goal of touching down at a specific point on the runway. Glider pilots can try for longer flights, while jet pilots might set the goal of becoming airborne. Anything goes, so long as it's a challenge and some satisfaction can be had in the process and accomplishment.

2. Cross Train: Try a little bit of everything, even if it's not your primary aviation interest. Some different fields to explore are as follows.

• Free Flight: No you can't control these after they've left your hand, but you don't have to buy a radio either. We are blessed to have several accomplished free flighters among us (Gene Smith, Larry Kruse, Gene Post & Don Abbot) and access to a large field in which to chase models.

• Pylon Racing: Now this one's a rush. We've got the pylons-race what you've got. Quickie kits like the Scat-Cat are pretty inexpensive (around $30), but I've raced a Goldberg Eagle against Mark's Eagle. It may look boring, but head to head racing is always exciting for the pilots.

• Slope Soaring: There are two locations locally that can sustain gliders (given a good south wind, that is). The Gentle Lady apparently rules supreme in Stillwater, but occasionally the wind is strong and straight enough to keep heavier ships aloft. Bring some 5 minute epoxy and CA for this one as you're never very far from the hard stuff!

• Aerobatics: Everyone tries aerobatics, but few actually decide a routine before they leave the ground. Even loops and rolls can be challenging if you determine your entry and exit points in advance. Watch the "Wring it Out" videos for inspiration here.

• Soaring: While working the thermals ( around here ) can drive you to drink, you can investigate different avenues to getting aloft. Paul likes to carry gliders up on his Aeromaster with a cradle of his own design. I prefer a straight air tow, although the glider and the tug need to be matched somewhat in flight speeds etc. Power pods, Hi-Starts, hand tows and Pauls arms are good options also.

• Helicopters: While it may cost a little more to "try" this one, it is fascinating and challenging. I understand that heli's are able to perform many of the same maneuvers as fixed wing aircraft, but I've never seen an R/C plane hover!

• Scale Flight: How about trying to make your model appear as realistic as possible? Slow climbouts, gentle turns, you'd be surprised how challenging scale flight can be. We have examples a plenty flying across the field from the airport.

So you've got the R/C blahs? Set two goals, use your imagination, and you'll be fine by the weekend!

Sloping

by Bob Norvell

Too windy for all trainers, and even your low-wings and sport planes won't be much fun? Check the wind direction. South to southeast, you say! Dust off your gliders and hit the slopes!

While there are definitely limits for most thermal soaring gliders, a nice steady south wind of at least 8mph seems to be the ticket around here, and the straighter and stronger the better. Here's how it works, according to our limited experience. When a straight wind encounters a slope, i.e. a dam or hill, the airflow is temporarily directed upward. Given a reasonably wide and steep slope perpendicular to the wind, the resulting updraft is sufficient to keep your glider aloft almost indefinitely. Think of it as a thermal that never moves(pretty neat, huh?). As a bonus, when the wind is redirected upward, it's not as fast as the wind moving across flat ground, so that a glider isn't just blown away. Any glider can be slope soared, but maneuverability is a good thing. The Gentle Lady seems to rule in very light conditions, but I've seen many models(Spectre, Wristocrat, Skeeter, Metric) perform well in moderate winds. When Gary England is on the StormTracker, it's time to get out the Coyote and Ridge Rats for some serious excitement.

As with thermal soaring, the object of the game is to find and stay in the areas of maximum lift.Unlike thermals, though, the lift zones are fairly constant and well-defined. Keeping close in to the slope at the crest is the most reliable method, making tight pylon-style turns into the wind at each end of your run and bringing the glider quickly back into the lift zone. In marginal lift, it is important to complete your turn and get your wings level again to stay aloft. The basic flight pattern resembles a very long figure"8". In better conditions, there is another lift zone in front of and above the slope, 40 feet or more out at about a 45 degree angle. By building some speed along the slope and making a climbing turn , you can find your glider way out there almost hovering. From there you can try loops and rolls without the immediate danger of hitting the slope.

1. Keep the nose down! Especially on a first launch, you don't want to get blown back behind the hill where the airflow is downward at best.

2. Go fast! Ten feet off the ground is no place to practice stall recovery. It's amazing I know, but if you are going downwind at 20mph in a 20 mph wind, you're stalled. (Actually, it looks pretty cool until the ground jumps up and grabs your plane)

3. Nevernevernever ever turn downwind, towards the slope! (See #1 and #2)

4. Because of the above tips, take along some 5-minute epoxy, wide tape and CyA glue.

5. HAVE FUN!!!

Tip of the Month

by Neil Retherford

This month I've got a building tip for the Scat Cat quickie 500 builders. This will also work for any model with a small firewall. Have you drilled the engine mount holes in the firewall and discovered that the holes passed through the triangle stock in the corners? It's difficult to mount the blind nuts if there is no flat. Use a Dremel stone with a diameter at least as big as the diameter of the blind nut. Insert the shank of the stone through the drilled holes from the inside of the tank compartment. Chuck on the shank and turn on the Dremel and pull back gently against the triangle stock. In a short time you will have a round flat centered on the bolt hole that will accept the blind nut. See the illustration.

Aerobatics 101.1

The Hammerhead
by Eric McRae

The hammerhead turn is a vertical stall maneuver. It is usually entered from straight and level flight, with full power. Pull back stick (up elevator) until the plane reaches vertical and slowly reduce power to about 30%. Apply necessary right rudder during the decelerating climb to counter the torque effects of the engine and apply elevator and aileron as necessary to maintain pure vertical tracking. Your plane will slow and finally stop, completely stalled. At this point or just slightly before, apply full left rudder to initiate the turn-around. Some aircraft will begin to roll due to roll coupling tendencies from the rudder. If this should occur, you will need to apply some right aileron to keep the turn flat. As the flat turn is completed, a short but strong input of some opposite rudder (in this case, right rudder) may be required to keep your plane's tail from rotating past the vertical centerline. On the downward leg, slowly apply power and apply back stick to straight and level at the same altitude that you entered the maneuver. Even with a simple maneuver there are lots of things to think about and many variables that may force you to modify your plan. Check your plane for roll coupling.

Fly straight and level (Trimmed for hands off) Apply quite a bit of left rudder. Does the plane roll left? If it does then it exhibits roll coupling and when rudder is applied in the hammerhead, opposite aileron will have to be used to correct it. Also, since airspeed at the top of a hammerhead is practically nil you will probably have to use generous amounts of aileron. (In truth only the wing on the high side of the turn is even remotely flying) Concentrate on the rudder first. Keep entering the maneuver and try to time the rudder just as the plane stalls. Do this over and over until you are comfortable with the climb and stall of your plane. Don't worry about the rest of the maneuver, just recover and enter the maneuver again until you master that part. when you break down a maneuver in this way you train your mind and hands to do the required inputs without much conscious thought. Then you can begin using aileron to keep the turn flat, concentrating on that portion of the maneuver. Keep adding elements of the maneuver, one at a time until you get it. Have fun!

Tip of the Month

by Neil Retherford

Many of you may have shop tips or field tips that you assume everyone must know. Believe it or not you could be a wealth of information to the new guys as well as to the old hands. This month I'm going to offer one of my simple but useful tips.

Many times during the construction of a model I need to prop something up or shim a part into position (i.e., wing tips, ribs, trailing edge, etc.). Most of the time there is nothing the right size or thickness to do this. My trick, is to take a piece of trailing edge stock, or aileron stock, and cut it into pieces about one to 1 1/2 inches long. Use the most crooked and heaviest stock you have. Don't waste the good stuff. Then use the wedges you've made, and shim the part to just the perfect height or position. You can also stack multiple wedges to get the height required and then clamp the assembly in place with a T pin.

How to Build a 3 Station In-Wing Bomb Release

by Mark "Bomber" Vasoll

This is a follow-up to my first bombing related article back in 1991 that described a single bomb release designed to be strapped under the wing of a flat-bottomed airfoil trainer (like the Eagle). Since that time I've moved on to a saturation bombing approach with a 3 station bomb release built into each side of my Eagle's wing.

Macramé bead bomb with streamer.

Now, make some bombs out of what ever is handy (make it light, so it won't dent people's cars or bodies should it get away from the drop zone). I use macramé beads with a loop of paper clip as the bomb attach loop and a short length of survey flag (to make it easier to find in the grass).

Now.... Practice, practice, practice.

A Wing Carrier

by Mark Vasoll

Wing Carrier Illustration

As the maiden flight of my 1/4-scale Citabria comes closer, I have started making support equipment. My latest creation is a simple wing rack to improve the utilization of available space in my truck. This will enable me to continue bringing more than one plane to the field, even if one of them is very large.

The frame is made of 2" x 2" furring strips which are glued and screwed to make a rigid structure. The dowels that hold the wings are 3/4" x 12" and are set at an angle so that the wings won't bounce off the rack due to bumps and curves on the road. It is important that the holes for each dowel be at the same angle, so you'll want to use a drill press when drilling these. The dowels are glued in place and some pipe insulation is then slipped over them to both cushion the surface to prevent wing damage and also provide some friction to keep the wing from sliding around.

I hold the rack upright in the truck by rubberbanding a couple of 1/4" dowels that go through the top frame member to the coat hooks that happen to be in "just the right place" in my truck. You may have to do something a little different for your vehicle.

Lessons Learned...

by Gene Smith

Model aircraft fuel systems are really simple, right? A tank, a line to the carb, and a line to muffler tap, simple! How is it possible, that about 30 things can go wrong with this setup? My latest faux pas occurred with my Champion 45L. The Champion had been flying reliably with good motor runs. A few months ago I noticed the engine was leaning near the end of the flight, more than usual. The next flight was terminated when the engine went lean fairly soon after launch. Inspection at home revealed wet foam in the tank compartment. Inspection of the tank revealed that the end cap, which threads onto the tank, had worked loose. I cleaned up the tank, screwed on the cap, and sealed the cap area with silicone. It should stay put now.

I had also been having trouble with the Fox .40 on my Scat Cat going lean and burning out plugs. It had run reliable in the past. Mark Vasoll found a crack in the fuel tubing near the motor. Moral of the story: If your motor tends to go lean, look for a fuel/air leak.

After years of racing Formula One and Quickie without losing many planes, I began to have a rash of mysterious crashes that eventually led to my dropping out of racing. I just could not keep a plane in the air. This year I finally discovered the gremlin that led to the demise of about 5 Quickies. For years I used the small Bantam Midget servos from Ace RC. They were dependable and light, but are no longer available and are too small for use with current Quickie speeds. Until the last year or two I raced, I used a commercial servo mount. However, in my last few ships I mounted the servos directly to plywood cross braces. The problem was that the commercial trays held the servos securely, but the direct mount method with pan head screws allowed the elevator servo to pop off the mount under the force of a pylon turn.

This problem was discovered with my maroon Scat Cat which wrecked twice before I tumbled to the cause. I re-installed the servos with thin ply keepers over the grommets and the Scat Cat has been reliable ever since. This problem would probably not be seen with regular servos in a sport plane, as most servos have stronger lugs and larger grommets, plus they do no have the strain of pylon turns.

Building a small plane(?), .049 gas or small electric? I saw this tip recently. Use a PAY DAY candy bar wrapper as rudder/elevator hinge material. I can see how this would work. It is really tough, yet flexible.

Winter Check List

Check for:

• Loose servo mounting screws.
• Worn clevis pins(plastic clevises) or worn threads (metal clevises).
• Flexing push rods.
• Loose horns.
• Loose or broken hinges.
• Put fuel tubing keepers on all clevises to keep them closed.
• What do the servos sound like in operation. Do gears sound worn or does the servo sound like it's straining or slow? Is there any binding in the pushrods or control surfaces?
• Loose engine mounting screws.
• Loose muffler screws.
• Leaks in fuel system (tank stopper, fuel hoses, brass tubing etc.)
• Check capacity of receiver and transmitter batteries.
• Cycle nicad for glow plug.
• Check for broken glue joints.
• Tighten up covering with heat gun.
• Clean transmitter.
• Check receiver switch. If intermittent then replace.
• Check for chafing wiring in plane and antenna.
• Plug and unplug wiring 2 or 3 times to remove corrosion.
• Center trim levers if they aren't already (adjust clevises).
• Check for frayed wiring on starter.
• Clean out field box and rearrange.

Two Cycle Model Engine Tuning

by Mark Vasoll

Using this procedure I make needle valve adjustments only a few times per year. Mostly they are caused by fuel brand/grade changes and large temperature changes. What follows is a step by step guide that should have your engine properly tuned with minimum fuss.

• Secure the plane, use a helper as needed. You will need both hands free to tune your engine properly.
• Start your engine and set the throttle at maximum.
• Open the high speed (main) needle until the engine is obviously rich. It will be spraying raw fuel and running rather slowly.
• Slowly close the needle until engine speed just starts to increase.
• Briefly pinch the fuel line near the carb inlet and listen for an increase in engine sound pitch (rpm increase).
• If an increase was heard, close the needle a bit more and repeat the pinching process. Continue this way until the rpm does not increase when the fuel line is pinched.
• Now open the needle about 1/4 turn.
• Your high speed needle is now correctly set. If pitching the nose of the plane up or down causes the engine to lean out and die or become overly rich, you have fuel system problems. Check for leaks, kinks and so forth.
• Reduce throttle to idle for about 15 seconds (or if it won't run that long, for as long as possible without the engine dying).
• Quickly advance the throttle to full power.
• When the throttle reached full power, was there a larger amount of smoke/oil for a moment or did the engine slowly come back up to power? If so, your idle (low end) needle is too rich.
• When the throttle reached full power, did the engine quit suddenly? If so, the idle is too lean.
• Again, difficultly in finding a good setting probably indicates fuel system problems, glow plug problems or fuel problems. The quickest thing would be to switch to a new plug and repeat this entire procedure. Failing that, borrow a tank of fuel from a buddy and see if your fuel is perhaps spoiled or your engine just doesn't like the fuel you've selected.

Light Spackle Compound

From rec.models.rc

Last time I went to Sears I was looking around the paint department and saw a product called Spackle Lite. I bought some and found it is an almost exact match for CG Model Magic superlight filler. I have tried it on the plane I am building and it works fine. It is light and soft has a slightly rubbery feel to it that may keep it from cracking under stress. It can be thinned with water and I think it works as well or even better then the Model Magic...

Now for the BEST part:
it has always upset me to pay $7.00 for a 8 fl oz jar of Model Magic, I think it is WAY over priced. The Spackle Lite at Sears only cost $1.97 for the same amount. that is a savings of $5.03 on each jar. You can also buy a quart size for $3 something, that much may dry up before you could use it all, but you are still ahead.

to sum up:
The product is called Spackle Lite made by Muralo I found it in the paint department at Sears and is in a small white tub similar to Model Magic .

Preperation of Plastic Propellors

by Joe Wagner

The following was received from Ken St.Clair by e-mail.
This tidbit was received by Ken from Joe Wagner via e-mail.

Plastic props (such as Master Airscrew) have sharp leading edges and tips because that's the way they emerge from the molding dies. It would add a LOT to the selling price if the manufacturer deburred those razor-like edges at the factory.

Several years ago Model Airplane News published an article of mine about model props, in which I recommended rounding off the leading edges and tips of molded plastic props. I said doing that would not only make the props safer, but would actually improve their efficiency.

There were three interesting results from that article. First, Windsor (makers of Master Airscrews) immediately cancelled their advertising in MAN. Second, the publishers of R/C Report performed a series of tests to check my statement that a rounded leading edge makes a propeller work more efficiently. They got even better results than I did, and published an article saying so. Third, in a few months Windsor began an advertising campaign in other model magazines, containing "safety recommendations" IDENTICAL to mine in the earlier MAN article.

Sharp TRAILING edges DO maximize model airplane propeller efficiency. Rounding off the trailing edges of, say, an APC prop will noticeably reduce its effectiveness. However, it's not the TE that digs into your flesh when a prop "bites" you.

It takes only a minute or two to round over the leading edges and tips of a molded plastic prop. (My preferred method is by scraping with a sharp, rigid steel blade. Some abrasives also work -- it depends on the material the prop's molded from.) Compare the time it takes to "deburr" a prop to the time it takes just supplying the "paperwork data" to the Admitting Nurse in a Hospital Emergency Room...

True, a "deburred" propeller is STILL a dangerous device. On my own carefully-radiused Graupners and MasterProps the leading edges are probably sharper than the blades of most power lawnmowers -- and have higher tip speed too. But at least I won't badly slice two fingers just lifting one of my models out of the car -- as happened to one of my friends last summer who used the "buy 'em and fly 'em as is" method with his plastic props