Helicopters
Walt Schoonard
BY NOW, let's hope that you have purchased a Heli-Baby kit. This is, without a doubt, the finest small helicopter to come on the market to date. I say this because of fine engineering and flight characteristics. I have over 50 hours of air time on mine, and, each time that I fly it I am more impressed than ever before. However, I have found some wear points, and have made some mods to increase their life.
There have been some very good articles published about building this helicopter, but this article will deal with flying the Heli-Baby. I don't mean to tell you how to fly it but rather to pass on to you my findings.
The old "pet" engine theory holds true with this helicopter too. I have seen them flown on all kinds of engines, and it still holds true that you cannot overpower a Heli-Baby either. It will fly on most any .40 engine that you can get into it, but the .40 Schnuerle really do a fine job. This shows up when you make a rapid descent and then try to stop before slamming into the ground. The two engines that show abundant power are the Webra Speed .40 and the .05 Max .40 Schnuerle. I have the Webra .40 Speed in mine, and it flies on one-third throttle which leaves a wide margin of power to spare. This spare power is available on command, and I'll tell you later how to use it to an advantage.
Some mods must be made to get this engine into the Heli-Baby. First, the drive spool on the Webra must be turned down so that it will go into the fan recess. About .050 thousandths will do fine. This then lets the fan come too far back, and it strikes the carburetor. I use a Kavan carburetor — the .61 fits the .40 also. The front of the carburetor has to be cut off to miss the fan. This can be done with a Zona saw and finished with a file. If the fan is still too close to the air-blade screw, then place a washer between the fan and the drive spool to make proper clearance. You will then need to make four small slots in the side frames to clear the backplate bolts. The motor will now fit into the Heli-Baby with ease.
Why do I use a Kavan carburetor on this engine? First of all, this helicopter must have an instant engine response. It must also be linear from full slow to full high. This carburetor has an excellent idle and is linear all the way through. The control arm can be loosened and positioned as needed. I have mine set up so that the arm is 90° to the pushrod when the servo is in the center position. The air bleed can be preset at half open before installing, and on the K&B 500 fuel will need no further adjustments. Set the barrel stop so that the engine can be stopped by closing the barrel on low trim. Engine should start on low throttle and middle trim. High trim should engage the clutch. I use the Schluter starting belt on mine, and I highly recommend using an electric starter over the hand starter. I use a Semco 202 CBT muffler. It is very quiet, and the rear exhaust makes a very clean running machine.
My Heli-Baby weighs 6½ pounds with a full tank of fuel. It hovers at half throttle and flies at one-third. The extra power does not make a hot rod of it but rather a wide reserve power margin. From a hover, if you just push forward on the stick, it will go forward alright and run right into the ground. How far away will depend on how high you are hovering. So as you push forward, add some power. Now, if you are using most of your power to hover, where will you get the needed extra power?
In transitional flight, I use forward trim so that it will fly away from me hands off. In a turn, I apply rear cyclic and left or right cyclic and add power. The turn is now made with little or no cyclic control but rather with power. This leaves nearly all the cyclic control left to use should you need it. Climbing is done the same way. This has enabled me to loop the Heli-Baby in stock form. Recovery from a loop is done with power; thus the tail does not drop, and the loop is much tighter and safer. I am sure that this sounds like an odd way to turn and climb, but you must realize that the main rotor blades are very small and have little pitch. If turns and climbs are made with cyclic only, you will be doing so on one blade, and a stall will result. I have been able to do sustained knife-edged flights with this machine. Do it cross wind with the wind into the top of the rotor. Start your practice with a lot of altitude, and when perfected, you can do it head high. With forward trim, achieve a lot of speed downwind, then turn cross wind and roll to the left and add power and some right rudder. Then listen for the applause from the spectators!
When doing landings from transitional flight, turn your favorite direction and roll it on its side as it goes downwind and come off the power to suit the descent you want. Turn into the wind with tail rotor and let it slip in towards you. Hold back on the cyclic to keep the nose high and then stop—add that reserve power and right rudder and watch it stop in mid air! Now forward cyclic and reduce power to let it descend to a smooth landing. Hold some left rudder as you come off the power, and you will make it look very professional.
Now bring the power up smoothly, adding a little right rudder and forward cyclic, and take off with a little rear left cyclic. Pull around your head in a tight circle and do the landing again. Now stand back and take your bows—you have earned them!
Just remember that turns and recoveries are done with a little cyclic and a lot of power. When you have become acquainted with the Heli-Baby, you can do spins at high altitude by adding power and then left tail-rotor command. To stop spinning, just let go of the rudder and fly out of the spin. Later, when you get brave, you can do spiral take-offs adding power, left rudder, and literally screw the sky.
Almost everywhere you go, helicopter pilots complain about the wind. Well, let me tell you, this little baby loves the wind! I have flown in 30-knot winds at our state symposium with this machine, and the only hairy part is when you come to land from a hover. This requires some deft stick movements and some tight concentration. I do recommend adding some weight to the nose for windy conditions. Further stick-on lead is great. Stick it near the front end under the floor. The added weight is also helpful in doing loops. Why, I do not know, but Horace Hagen suggested this, and it works great!
Wear Points—Mods to Improve and Prevent Failure
The control arm on the fly-bar tends to move, and this can cause loss of control. Remove the Allen set screw and replace it with an Allen cap screw like the ones used in the blade holders. Cut it off to proper length. This will permit a larger wrench, and it can be tightened where it won't come loose.
The tail rotor is turning the same speed as the engine (12,000-14,000 rpm) so some things in this area need to be improved. First of all, the T/R blades tend to sling off, and I am sure that you can imagine what will happen as a result. A simple fix is to epoxy a small piece of 32nd plywood on the back side of the blade in the holder and redrill. I have some 50 hours on the same T/R blades, thus modified. Another wear point is the belt pulley in the rear. It is centered by the needle-bearing cages, and the constant pulling of the tail rotor to the left wears the gear on the left side. This will cause the T/R shaft to move back and forth and a very sloppy T/R centering will result.
DuBro collars can be drilled out or use Kavan blade balance collars. Put one on either side of the T/R shaft outside the needle bearings and tighten so that there is no bind or slop. The collar must be routed to clear the collar. This has moved the wear point outside where it can be lubricated easier and adjusted out as wear occurs. The pitch control trailing plate is nylon and squeezed between two trim collars, and heat results that can melt the nylon. When this happens, you will lose T/R command, and this will crash the machine, right now. A small washer between the collars and the nylon will provide a bearing surface and prevent heat build-up. Lubricate this and the tail-rotor bearings each flight. Yes, I said each flight!
The tail-rotor belt should be adjusted just so it won't slip. Check by holding main rotor and tail rotor. Only tighten just so it won't slip under moderate pressure. You probably will find that the tail boom is sandwiched between the holding bolts so it won't easily adjust. This can be improved by slotting the lower-bolt hole slightly so that, when loosened, the boom slides easily. I hope that this article will increase your flying pleasure with the Heli-Baby.
I have developed some hardened tail- rotor shafts and main-rotor shafts; also, seesaws that are three times harder than stock. I also have blade holders that don't split blades when you tip over. These are all available from Miniature Aircraft Supply, 2563 Diversified Way, Orlando, Fla. 32804. Phone 305-422-1531. I have a complete setup of the Heli-Baby that I will send to anyone that sends me a self-addressed stamped envelope requesting Heli-Baby setup. If you aren't flying, you aren't trying!
(My address is 2080 Sharon Rd., Winter Park, Fla. 32789.)
Transcribed from original scans by AI. Minor OCR errors may remain.
