From The President

“In like a lion, out like a lamb”, or is it “In like a lamb, out like a lion”? In Oklahoma it’s anyone’s guess, but we’ve had some great flying weather lately and it’s only going to get better. We had a great turnout on Sunday afternoon (Mar 9) and I couldn’t pass up the beautiful day on Tuesday Mar 11 either. Naturally, the wind picked up as soon as I got there but it wasn’t all that bad. All in all those were two great flying days and plenty of action for everyone. I only wish I could have gotten out more during the month.

If you weren’t at the February meeting you missed a lot of fun and a great presentation by Jerry Britsch on applying fiberglass cloth. We had a drawing for a rather interesting selection of parts, old radios, airplane kits, etc. and Bill McArthur won the $5 Trivia prize. See the official meeting minutes elsewhere in this newsletter for further details. And, you don’t want to miss the March meeting when, among other things, Dan Quinten will brief us on the upcoming Senior Pattern fun-fly. Sounds like a lot of fun and good times to be had.

Other items on the agenda include:

Ø updates on Heatwave ’08, Gatesway Balloon Festival, TGD fun fly events (several in the works), possible dates for a field Spring cleaning work day, etc.

Ø upcoming Bald Eagles fun fly announcement and dual membership offering

Ø discussion about Beginner’s Training Night

Ø results of the Member Survey

Ø Old and New items of business

Ø If you have a project underway and would like to tell us about it, bring it along and we’ll make time for you

So, grab your best bud and bring him to the meeting. We’re back on our normal meeting schedule for March 25, Martin Regional Library, 7:00 pm. We’ll have some fun things and Doug has some more of those nifty items for a drawing.

See ‘ya on the 25^th, and keep flying safely.

Jack Rogers,

President

Minutes of February Club Meeting

The February meeting of the Tulsa Glue Dobbers was held on Thursday, February 28, rather than on Tuesday because of a library function conflict. The same will happen in April when we will meet on the fourth Thursday rather than Tuesday. March will meet at the usual time. Twenty four members were present. The minutes of January were read and approved. Jack Rogers welcomed three newcomers to the meeting and then recognized the birthdays for the upcoming month.

In old business, it was announced that the War Bird fly-in scheduled for June 21 would conflict with the Copan event, and in order to respect their use of the date, we will seek an alternate schedule. Other fly-in events were announced, most of which were float fly events in Kansas and Missouri. Dave and Walt Hendon attended the meeting after a long absence, and Dave reported on the indoor electric fly-in that he hosted at the old Rose Bowl building. About thirty people attended, Brandon Chitty put on his usual unbelievable show and only thirteen people had to be treated for hypothermia in the unheated Rose Bowl. Dave hopes to continue hosting such events monthly.

In new business, Calvin Campbell brought one of Brandon’s old foamy planes for show and tell. It was the plane that Fancy Foam built for Brandon’s winning routine at the 2006 indoor TOC event. Jack announced that the Gatesway Foundation wants the TGD to participate in their big balloon festival at Will Rogers Downs. After some discussion, it was decided that Jack and Chris Raymer will travel to Claremore to investigate the suitability of the site for us to fly our planes.

Tim Tipton reported that he and Dan Quinton plan to host a Senior Pattern competition at our field on May 3 and 4. This competition requires planes from the 70’s era and earlier with no pipes and no retracts. Rules can be found at seniorpattern.com. We then discussed the scheduling of a spring club picnic, a fun-fly event, and some pylon racing. Doug Bromley and Bill McArthur will coordinate the dates. Jack then asked for input about a spring clean up and repair of our facilities, and announced that we will be taking bids on a mowing contractor for this season.

The main program for the evening was a demonstration by Jerry Britsch on the water based urethane method of fiberglassing. He offered many tips and showed us what a wonderful surface can result from this process.

Finally, Doug held a drawing for several door prizes that came from the estate of Glue Dobber member John Mannix who passed away in September shortly after moving here from Boston and joining our club. More items will be offered at the March meeting. The meeting adjourned at 8:50 pm.

Submitted by

Doug Bromley,

Secretary

APRIL BIRTHDAYS

Happy Birthday to these ‘Dobbers

Autogyro Aerodynamics

After reading many explanations of how autogyros fly, I have come to the conclusion that the discussion can get too technical too quickly. Let’s start with a simple analogy.

Some kinds of maple seeds have a wing with an airfoil. It spins as it falls, and the upward force on the blade slows the fall. The force that keeps an autogyro airborne is the same that acts on the maple seed. Now if you attached a thread to the seed and pulled in horizontally as it fell and spun, it would fly! Well, maybe it would need a tail and a more efficient blade, but you get the point. The arc of the rotor would angle back a bit, and the resulting upward force would be greater than the gravitational force.

Hopefully, from this explanation, you can see the differences between an autogyro and a helicopter. Most importantly, an autogyro rotor is not powered. It is simply freewheeling in the wind. The plane of the blades is titled back opposite the direction of travel, not forward like a helicopter. And the blades have a negative angle of attack. This makes sense because if they had a positive angle of attack they would spin backward when the wind hits from underneath.

Most autogyro blades have a special hinge to keep them at the proper angle of attack.

The hinge line is at an angle to the blade, so when the blade tilts up, the angle of attack decreases (leading edge is lower.) And if the blade tilts down, the angle would increase, but a stopper blocks the downward bend. You don’t want the blades dropping and hitting the airplane. Hinging the blades also helps to decrease unwanted roll forces caused by the differences between advancing and retreating aerodynamics.

Preflight Inspection

Preflight training teaches the student how to inspect and prepare his model for flight. Like full-scale airplanes, a model airplane flight does not start with takeoff and end with landing. It starts with preflight inspection and ends with inspecting the airplane for any damage because of hard landings or suspicious behavior during flight. As are full scale airplanes, our model airplanes are complex machines. To ensure a successful flight we must make sure that all components are in proper working order.

We are in this hobby mainly for the fun, but we all crash—we just don’t know when. Even trainer models flown with an instructor using a buddy box will crash. The causes can be component failure or pilot error; yes, instructors err too.

To keep it fun we have to follow safety rules—both general safety rules as well as specific rules that apply to our model aircraft field. Students must learn to follow these rules to ensure that all pilots and spectators are safe and property damage, if any, is limited to our model airplanes only. Safety is of concern to everybody—all pilots at the field whether club members or not, flying or not, spectators, and people just passing by. All model-aircraft pilots should enforce the rules and make bystanders aware of potential hazard areas around the field.

Inspection of a new airplane starts with checking the integrity of the main glue joints and all screws. A student’s model comes to the field already assembled so it’s not possible to thoroughly check whether it is perfectly put together—whether it’s scratch-built, built from a kit, ARF, or RTF. Despite this, an instructor is able to check the components that are likely to fail under stress during flight. These likely failures are the wing joint, tail feathers, control surfaces, landing gear, engine mount, and firewall.

Models are not considered airworthy if there are any problems found. Remember, you’re a winner when you get your airplane(s) home in one piece even if you haven’t flown them. Any problem(s) found need to be fixed and another inspection performed. Some of the problems can be fixed right at the field. Others require more time and the convenience of a workshop.

Test the wings by placing the center flat on your chest and pulling the wingtips with a reasonable force. Performed the test in both directions—top and bottom of the wing. The joint should not crack. Some ARF and RTF manuals state to use tape or small plastic straps and screws to hold the wing halves together. My advice is to glue the wing halves together using 30-minute epoxy unless the wing is specifically designed to use a different method, such as the NexSTAR wing.

Pulling the tail feathers up, down, and sideways should not move them. Again some ARFs and RTFs use studs glued in the fin and nuts (with plastic inserts to prevent them from unscrewing) to bolt the tail feathers to the fuselage. It’s somewhat handy for transportation and storage but they are also more likely to fail, so my advice here is to glue them in place while still using the nuts.

Pulling the control surfaces—ailerons, elevator, and rudder (and flaps on some airplanes)—is the easiest way to check them. They should stay in place. Inspect the hinge gap; is it too big? If so, seal it. The easiest method I’ve found is to use regular Scotch tape. I always carry a roll in my flight box for repairs at the field (including repairing holes in the covering caused by landing in the weeds).

Check all linkages: there should be no play or slop. Play or slop in the linkages as well as big hinge gaps can cause flutter that can in turn destroy the wing, stabilizer, or fin to which it is attached. Although trainers have smaller control surfaces, moderate speeds of operation, and are not very prone to flutter, it can still happen—usually after the beginner pilot has soloed and starts performing aerobatic maneuvers with the trainer model at higher speeds. It happened to me; I lost my trainer due to aileron flutter.

Check all screws. I put Loctite on all metal to- metal screws—from landing gear to fuselage. Don’t tighten any engine screws if you are not familiar with the particular engine and its carburetor. Some of these should not be tight at all while others are torque-and sequence sensitive.

All wood screws should be tight, too. Use thin cyanoacrylate glue to harden the holes. First, run the screw in the hole so it taps it, then remove the screw and put a drop of thin cyanoacrylate glue in the hole. Wait for the cyanoacrylate glue to fully cure and reassemble the part. These include, but are not limited to, servo screws—the ones that hold the servos to the servo tray—hatches, tail landing gear (most high-wing trainers are not tail-draggers but use tricycle landing gear and don’t have a tail wheel), main landing gear, etc.

Most RTFs come with already assembled engines and landing gear. Usually they are not properly tightened and sometimes they become unscrewed and fall in the box. The result is a model that arrives at the field with screws missing or not tightened. Beginners are not knowledgeable enough to notice or even know how many screws should be used, and are mislead by the Ready-To-Fly advertisement of the product they just acquired.

Check the propeller. Is it the proper size for that particular airplane/engine combo? Is it suitable for training? Small diameter highpitch propellers provide a lot of speed that is not needed for a trainer model. A typical propeller for a .40-.46 size engine on a trainer plane is 11 x 5. Next, check to see if the propeller is properly attached to the engine crankshaft. The propeller nut should be tight—very tight. The modern engines have hardened crankshafts and use hardened propeller nuts, so don’t be afraid to tighten it. With an electric starter, from a safety and ease point of view, a spinner or spinner nut should be used. It should be tight, too. If the screws holding the spinner cone to the backplate are not tight, the cone will start to vibrate when applying the electric starter and shatter if it is a plastic one.

Check the center of gravity (CG) of the airplane with an empty tank. An improperly balanced airplane is hard to impossible to control. If done at the field and it’s windy, try to find a place where the wind will not affect the airplane’s attitude. Using your fingers is not the most precise method but it works. For most trainers the CG is located at the main spar. Check the CG with the fuel tank empty. When it’s full, the CG is slightly forward. It’s easier to fly a slightly nose-heavy airplane than a tail-heavy one. Most of the fuel is gone by the end of the flight, so the CG goes back to where it was set up with an empty tank.

Check the direction and the amount of control surface deflection. Do not exceed the manufacturer recommended values—they make the model more sensitive to the controls. That, combined with the inherent tendency of beginners to over control the airplane, will lead to aggravation from the student. He or she will be constantly fighting the airplane.

Do a thorough range check with the transmitter antenna fully collapsed and the engine running at idle, half, and full throttle. You can do it while breaking the engine in (if the engine is new). The servos should not twitch when you walk up to 30 paces (60 feet) away from the airplane. Twitching servos might be caused by low battery voltage for the receiver and/or transmitter pack. (Were they charged overnight?)

Break in the engine. ABC/ABN engines normally take one to two tanks before they can run reliably. Ringed engines take longer. Run the engines on the rich side of the needle valve, especially ringed engines. The airplane is ready to fly when the engine can idle and transition reliably.

Some engines (Evolution) are advertised as factory broken in. My advice is to take the time to run at least one tank of fuel through it. After that, if its performance satisfies an experienced pilot, the engine can take an airplane in the air. Keep in mind that the engine will continue to break in until it burns a gallon or two of fuel. How much depends on engine design. During that period, the engine will require some readjustment of its needles.

Leave the maiden flight to an experienced pilot. He will fly the airplane and trim it out. He will also readjust the linkages if necessary when the airplane is back on the ground so the trims can be re-centered (if the transmitter is not a computer one).

It’s that time of year again! We have new combinations for the gate and the clubhouse. Now remember anyone flying that does not display the proper member frequency clip need to be questioned. This is the only way we can ensure that all at the field are insured for our one protection. Also, maintenance and improvements to the field cost a considerable amount of money each year. There is no good reason to allow people to enjoy the benefits of our facilities without participating in the costs of upkeep and improvements.