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Twist

May 1999

DC-GYRO CONSTRUCTION:

This model incorporates all the excellent aerodynamic characteristics of the "Suitcase Minnie" autogyro. It also has the new "flex" hub that is simpler to build than the mechanical hub. Being similar to the "Minnie" model, it can be sufficiently dismantled to permit packing in a box or suitcase for shipping or travel if desired. Before beginning construction, you must make an important decision: What motor size do you want to build? The .061 or the .09 or.10 powered model? The motor you select must have throttle control and will dictate the type and position of the motor mount and front bulkhead. The smaller .061 will mean that the bulkhead must be moved forward to aid in balancing the model, and that the bulkhead will be a balsa / plywood lamination, with the mounting plate completed of light plywood. If you are going to use a .09 or .10 motor then the bulkhead must be moved aft, and you have the option of using a fiberglass motor mount or a -hard- plywood mounting plate. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The recommended sequence of building is to begin with the fuselage sides and then the ply doublers, followed by the stick framing, and the bulkheads. Build the tail parts, cut & install the rear fuselage balsa block, then cut the slot in the block for the vertical fin. With the fin ready you can make the stabilizer and secure it in place with the small screws, which anchor into short pieces of Sullivan nyrod sleeving that are imbedded in the aft fuselage balsa pieces. Once this is completed, then you can proceed with the forward engine mounting, servo plate, top forward 1/16" sheeting, and then on to the rotor system (head, hub, and blades) etc. The landing gear, tail skid, and anything else left can be completed last. It is important to use light to medium balsa, nothing hard and heavy. The model must be kept as light as possible, or it may not fly.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1. FUSELAGE and TAIL CONSTRUCTION: NOTE: The fuselage construction shown on the plan is for the MP Jet .061 powered model. For the larger motors (.09 to .10) the front bulkhead may need to be moved slightly to accommodate the motor, along with extending the 3/32 balsa sheeting (with 1/64 ply doubler) aft to the tail rather than use the 1/8" stringers. This is done to strengthen the aft fuse and aid in balancing the model for the larger engine. Edge glue 3/32 balsa sheet parts together and cut out the two side sheets. Cut the 1/64 ply doublers, and then cut the lightening holes in the interior ones (not necessary for the outside pylon doublers). Using a thin coat of epoxy, laminate these parts together. Use weights to press and keep the parts together and flat. What you see below is the inside of each side. CAUTION: Remember to make a left and right side! Left and right fuselage assemblies:

(A) 1/64" ply doubler (B) Lightening holes cut in ply before gluing to balsa sides Take a completed sheet side, lay flush on the plan, and add the 1/8" strip balsa. Cut the 3 bulkhead parts, and laminate with the thin ply doublers where shown. Align the sides and bulkheads on the vertical view on the plan and CA/epoxy in place.

Outside of the left fuselage panel:

(A) Front bulkheads (B) Outer pylon ply doubler (C) Stick framework (D) Fuselage tail block

Bulkheads glued in place on the right side panel:

(A) Front bulkheads (B) Note the lightening holes cut in the ply doubler (C) 1/8" balsa stick framework Bulkheads and the balsa tail block glued in place:

Build the Vertical tail fin now, but do not cut the slot in the fin (for the horizontal stab) at this time. For the lighter .061 model, the stick framed vertical fin is used. Use the solid fin for the .09 - 10 versions. With the tail fin available, carefully cut the vertical slot in the aft fuselage balsa block. Use caution: This slot must have the fin fit snug (slightly tight) and be in vertical alignment with the upper fuselage pylon sides.

Be sure the stab and fin align squarely with the vertical pylon when cutting slots. On the fin, carefully mark and cut the slot for the horizontal stab. You can now make the stab assembly. Sand in a slight airfoil shape to the stab on the outside of the center section. Carefully cut and epoxy the stab dihedral tips, and then CA the small thin Carbon Fiber strips in place, on both top and bottom. The ply center plates are glued in place over the CF strips, both top and bottom. Insert the stab in the bottom of the fin. File/sand the slot just enough to permit insertion of the stab. Align the parts squarely with the fuselage, pin in place, and mark for the mounting screws on the stab. With a small hand pin drill, drill for the mounting

screws. Remove/detach the fins, and then hand drill (in the balsa block) for the 1/2" long nyrod screw-anchor pieces, and epoxy the anchors in place. Following this exact sequence will insure the stab, nylon anchors, and screws are all in perfect alignment. Bottom view of tail section:

(A) Carbon fiber strips (B) Tail skid (C) Stab fits into slot in the fin (D) Fin fits into slot in tail block Fuselage details:

(A) 1/32" rear receiver compartment sheeting (B) Triangular top sheeting supports (C) Servo tray Install the motor mounting you selected at the beginning. The mounting shown in these photos is the flat ply plate (with a Cox .074 installed). Prepare the one ounce fuel cell (Sullivan R-1) and drill the forward bulkhead for the fuel lines. If you have selected the .09 or .10 motor, you may want to use a 2 ounce fuel cell, and if you do, then place both the receiver and small battery in the compartment aft of the servo area to help counter balance the larger engine and fuel cell. Use small pieces of 1/4" triangular balsa (as shown in the next photo) to brace the bottom of the motor mounting plate (if this is what you selected). Triangular pieces are also used to provide support for the top sheeting. The Rotor Head must be built and installed on the pylon before completing the fuselage construction, to accommodate the servo tray installation.

Landing gear mounting:

(A) Triangular motor mounting plate (B) Gear wires in the block grooves (C) Plastic sheet and small screws secure the landing gear wires Cut the landing gear mounting blocks from 1/4" light ply, grooving the slot for the gear wires with a Moto / Dremel tool, and glue the blocks in place. Drill holes for the short 1/2" vertical portion of the gear. Bend the music wire gear, insert in the grooves and holes, and secure in place with a 3/8" x 2" piece of plastic, and several tiny wood screws ("Perfect # P101" 3/8"). Light weight wheels are necessary. Use Dave Brown "Lite-Flite", Hayes racing wheels, or make your own as shown on the plan from lite plywood and rubber "0" rings. Remember, the model is hand launched, thus it is not necessary to have large wheels for ground rolling. Note the position of the triangular pieces that form the servo plate support in the photo below:

(A) Servo tray (B) 1/4" triangular tray support guides Glue these servo plate support triangular pieces in place to the bulkheads only. Do not glue the servo plate. It is designed to slide within the triangular guides and be removable. Do not install the top fuselage 1/16 sheeting until after the servos and rotor/throttle connections have been completed.

Fuselage compartment detail:

(A) Receiver (B) Plastic bottom hatch (C) Battery (D) Aft receiver/battery compartment ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2. PYLON and ROTOR HEAD COMPLETION: If your work has been good to this point, the space between the top of the pylon tips should be approximately 1/4". Note on the plan the small shims necessary to hold the rotor head vertical without any wobble. Glue 1/8" balsa, file and sand as necessary, and harden the shims with CA glue. Cut the 4 (1/8" light ply) parts for the rotor head. Cut the hinge from .030-.040 polypropylene. If you cannot find any .030 poly, you may substitute the plastic from a 3 lb. coffee can lid, for the hinge. This coffee lid plastic is not as strong as PP, and is more flexible, so reduce the head/hinge spacing from 1/8" to 3/32". Also, if the lighter plastic is used, inspect it frequently for fatigue cracking / tearing. If you are using the .09 -.10 motor, you may use the "Sterilite" .050 Polypropylene for the hinge and substitute a micro size servo (Such as the Tower TS-10 or TS-11) for the roll and pitch positions. The .050 PP is a bit heavy/stiff for the sub-micro servos; therefore it is necessary to use the stronger servo when using the heavy PP. The photo below is of the "alternate" fiberglass hub. The rotor head on the right is of the standard polypropylene shown on the plan. Note that you can clearly see where the toothpick dowel pins are inserted in the head.

Clamp the two top head ply parts in position on the hinge, apply a little thin CA to prevent slippage, and drill for a single toothpick dowel. Note that the slots for the two wire rods are cut in the hinge before the assembly is clamped and pinned. Apply a little epoxy, insert a round toothpick in that hole, and allow the epoxy to cure. Once the parts are secure from moving, drill for and glue the remaining toothpick dowels. After these have cured, sand off the pins flush with the plates. Now align the bottom plates, clamp to hold, drill and glue the dowel pins as you did above with the top plates. An alternate method of cutting the above parts is to trace the parts on paper, spray with 3m 77 or other suitable spray glue, and press on to the material as a pattern for cutting. Then, again use the spray glue to hold the parts together for drilling and pin insertion. Rotor head assembly:

(A) Nylon/plastic bearing spacer (B) Bearings (C) Pitch rod connection The rotor shaft (3/32") and pitch lever arm (1/16") are made from music wire. Music wire tends to be slightly oversized, and it may be necessary to sand/file/polish it to accommodate the bearings. Before gluing the shaft in place on the head, check to see if your bearings will fit without polishing. If necessary, and certainly before gluing the shaft in place, polish the shaft in a drill press, using one of the bearings as a guide. Once the shaft is prepared, now carefully drill out for the 3/32 rotor shaft and the 1/16 or 5/64 music wire pitch lever rod. Notch the insertion end of each wire with a Dremel / moto tool and epoxy in place. The notches will aid in holding the wire in place. The roll lever arm is made from hard PC board fiberglass. If this material is not available, a suitable substitute is a Robart #331 ball link control arm (3/4" size). Thin plywood is not recommended. Connection to the roll servo is made with 2/56 wire pushrod or 2mm pushrod wire. The roll arm is subject to dual axis movement, thus I recommend you use a closed ball link connection at the arm if possible (DuBro

#2134). With these small models it is OK to use a "Z" bend, a small nylon klevis, or an "EZ" connector at the servo. The initial neutral lateral trimmed setting is to have the rotor level (0 degrees left or right). To connect to the pitch lever arm (1/16 or 2/32 music wire) slip a closed-ball link connector on the arm as shown on the plan. Hold in place with wheel collars. A 2/56 rod or 2mm rod wire is satisfactory for the pitch servo to lever connection. The initial neutral trimmed setting (pitch) is with the rotor shaft parallel to the front edge of the pylon (11 degrees tilted aft of level). The rotor hub is secured to the vertical shaft with 3/32" wheel collars. Separate the hub from the collars with one or two nylon washers. I recommend you use two (2) collars on the top for hub security. NOTE: For additional security, you can grind two small flats on the shaft where the set screws contact the shaft. A removable thread locking compound may also be added to the threads of the set screws for even more security. 3. SERVO MOUNTING: It is not necessary to use large high powered servos on these models. The new micro sized ones are ideal, and the sub-micro is perfect for the throttle control. I have found that servo failure in flight is rare, and damage generally occurs when you allow the rotor blades to strike the ground on landing, etc. You must be careful not to "bump" the rotor while handling the model on the ground, where you place unnecessary sudden stress on the servo gears. If you wish you can obtain metal gears for the Hobbico or Tower micro servos, and remove much of the concern over gear breakage. Cut the 1/8" light ply servo plate slightly large, then trim / sand to permit it to slide upwards within the guide slots formed by the triangular pieces. Servo mounting detail:

(A) Throttle servo (B) Lateral/roll servo (C) Pitch servo

head, and pull the servo plate down out of the fuselage. After installation & servicing, the plate is then pushed up into position and re-connect the rods to the rotor control head.

To connect or service the servos, you disconnect the arms at the rotor

This plate will be held in place by the bottom hatch. Mark for the servos and cut the openings. Note that the throttle servo is mounted with the lugs on the left side with the arm on the right side, when looking from the rear toward the front. It is important to use the micro-submicro size servos, since weight conservation / reduction is important. Use 2/56 rods, 2 mm, or .050 music wire for servo to rotor head connections. The standard factory servo arms with the servos should be fine for the pitch and roll, however you may have to fashion a longer arm on the throttle servo to accommodate the higher carburetor throw necessary. Use Sullivan # 507 cable for the throttle connection. Harden the end portions of the light 507 cable with normal electrical solder if desired. If necessary you can sub a .030 music wire in the # 507 nylon tube for this. The Servo to Receiver wires will pass thru the pre-cut holes in the bulkheads. 4. FUSELAGE COMPLETION: With the rotor head installed, the servos connected (including the throttle cable), you can now add the 1/16" sheeting along the top of the forward fuselage area (shown below) back to the rear Rx / battery compartment. Use portions of 1/4" triangular balsa to support the sheeting where necessary.

5. ROTOR HUB COMPLETION: With these small model gyros I use small model car ball bearings (Team Losi A-6912 XX, 3/32 x 3/16" ball bearings) obtainable at most model car hobby stores. The hinge material used in the rotor hub is critical for proper and safe operation of a model autogyro. I recommend you purchase a small STERILITE refrigerator container at WalMart, KMart and other such stores having the Sterilite containers. Look for a container with a flat lid large enough to make the hinges for the Hub and Head assemblies. Check the bottom of the lid for the triangle & number "5", and the letters "PP". Note: Use only a portion of the lid, not the large bottom of the container.

Rotor hub w/fiberglass hinge:

(A) Bearings (B) Nylon bearing spacer (C) Brass bearing sleeve

NOTE: The photo shown above is of the alternate hub (fiberglass hinge) construction, though nearly identical to the Poly hinge hub (photo below), the above hub features a rigid hinge of thin (.030) fiberglass. Blade holding tangs are not required of the hub shown here, with the blades being directly mounted to the fiberglass, and are free to flap. Note the extreme smallness of the ball bearings at the right.

Rotor hub w/polypropylene hinge:

(A) Polypropylene hinge (B) Brass bearing sleeve epoxied to bottom plate (C) 1/32" incidence shim (D) Fiberglass hinge (E) Blade tang parts

Rotor Hub Top View:

(A) Note the groove for up-flapping (B) #2 x 3/8" flat head screw (holds tangs plates together) (C) 2/56 bolts (that hold the center plates together) Rotor Hub Bottom View:

(A) Note the tangs fit tight against the center hub plate (B) The Brass sleeve is epoxied to the bottom parts only Cut all the 1/8" light ply parts, and the plastic hinge. The brass tube is used as a ball bearing sleeve. I recommend you mark and drill for the center brass bearing sleeve before you mark and cut the exterior dimensions of the center triangular hub pieces. This will enable you to ensure the bearing sleeve is as close to the actual center of the parts as possible. Alignment / centering of all parts is very important for the hub.

NOTE: The blades must be oriented at 120 degrees from each other, therefore use caution in cutting the hinge to assure this alignment, and when assembling the hub, the arms of the hinge must extend directly out (90 degrees) from the side edges of the triangular center parts, and radiate at the 120 degrees. Any deviation will create an imbalance in the rotor.

Once the center sleeve hole is drilled, align the top and bottom triangles with the hinge (using the brass tube), drill for and insert the 2/56 bolts. (As an option, you can drill and glue toothpick dowels rather than use the bolts, or use #2 x 1/2" wood screws). Insuring that the parts are aligned (the brass bearing sleeve is 90 degrees vertical to the

hub wood parts), use a little epoxy to glue the sleeve and the circular shoulders to the main hub triangles. The important thing is that the hub needs to rotate on the bearings without any wobble. Next we can assemble the blade tang pieces (the tang is the part to which the rotor blade is bolted to). Again, be sure the blade tangs align 90 degrees to the sides of the center triangle and radiate an accurate 120 degrees apart. The bottom tang piece butts tightly up against the lower triangular center hub piece. This is to prevent/minimize the blade droop. Note that the top tang piece is slightly beveled at the inner end to allow the blade to flap "up" about 15 degrees. It is not critical to have all tangs beveled the exact same amount, just be certain that at least 15 degrees of up flap is available. Clamp each tang set together on the hinge material, drill and insert the two small flat head screws which hold the tang plates together. An optional method is to insert/epoxy two toothpick dowel pins rather than the screws. The dowel pins will be lighter, but will prohibit you from taking the tang apart later if necessary. The choice is yours. Drill for the 2/56 blade mounting bolt using a 5/64 drill. If you have a 2/56 bolt tap, a good suggestion is to drill this hole with a 1/16" drill, then harden the hole with thin CA glue, and then tap threads in the hole for the bolt. This simply aids in keeping the blade more secure with less tendency to become loose. The second (inside) mounting hole is drilled with a larger drill (3/32 to 1/8"). The purpose of this is to hold a balsa stick shear pin. This balsa pin will help keep the blade aligned during pre-rotation, and should the blade(s) strike anything the pin will shear and prevent/minimize blade damage. The blades must be shimmed to insure a slight negative true incidence. If not shimmed, and simply mounted flat to the tangs, they will be set for a positive incidence of about 1+ degree, and may not spin up before launch. A simple and very accurate way to shim the blades is to cut small (1/8" x 1") pieces from 1/32" plywood and glue them to the aft edge of the blade tang as shown on the plan. This shim strip will set the blade to a slight negative angle of incidence of approximately 1°. I painted my completed hub assembly with Testors model paint, black.

blades resist spinning up in a light breeze, it may be necessary to increase the negative incidence slightly. Just be aware that the more negative the incidence, the easier to pre-spin, but at a loss of rotor performance. Ideally, it is desired to be as close to zero as possible and still be able to pre-spin the rotors. The rotors must accelerate into autorotation before flight is possible. You can recognize this autorotation by the rather sudden/rapid acceleration of the rotor. Even if your rotor appears to be spinning rapidly at the beginning, it may not be in autorotation. You can easily recognize the autorotation acceleration as it is very pronounced. Using the same thinking, if your rotor spins up quickly, but seems to lack lift, you may want to sand the shims slightly to decrease the negative incidence ever so slightly.

NOTE: The blade, if mounted flat without the shim, will have a positive incidence of about 1°+, and the rotor will be very difficult to pre-spin for launch. If you find the

6. ROTOR HUB - SHAFT MOUNTING:

(A) Bearing spacer (B) Bearings (C) Pitch ball link connections The rotor hub assembly is held in place on the rotor shaft with three 3/32" wheel collars. If you can obtain a small thrust bearing, use one. If not, at a minimum, use two nylon washers between the sleeve/bearings and the collars. I suggest you use two collars on the top to insure in hub does not come off in flight. Install the hub on the shaft with the top of the top wheel collar at the top of the shaft. A small thrust bearing, between the ball bearings and the wheel collars, helps considerably in obtaining a good smooth rotor RPM, however is not absolutely necessary for flight. In the absence of these thrust bearings, the nylon washers are necessary. An excellent thrust bearing is part# A 7 Z 7-012, available from "Stock Drive Products", New Hyde Park, NY. Telephone #516328-3300. This is a 1/8" ID (.125) bearing (the smallest they have) and costs only about $2.50 and is well worth the cost. The nylon washers are available in many hardware stores, and in the large stores such as Home Depot, Eagle, and Lowes. 7. ROTOR BLADES: NOTE: If you prefer to opt out of making your own blades, you can purchase AeroBalsa's item number 11218RB and save yourself a lot of time. www.aerobalsa.com (1) Select a good quality 3/16" sheet of lite to medium balsa 4" x 36", with a uniform grain throughout. By using a uniform weight sheet, it will be far easier to complete all blades equal in weight with a minimum of difficulty in balancing. Mark & cut the three 15 1/4" x 1 1/4" blade blanks. I usually make 4 blades at a time, having a spare is certainly handy in case you error while sanding the airfoil.

Note the 2/56 mounting bolts are installed away from the center of the hub, and the balsa stick shear pins are placed in the (1/8") holes closer to the center of the hub. The root ends of the blades are curved so that they will clearly pivot aft and shear the balsa pin if the rotor strikes anything. This method eliminates or minimizes blade damage.

Select very straight 1/8" square (or 1/8" x 3/16") spruce (or pine) strips for the leading edges. Cut to length, and epoxy to the bottom leading edge of each blade blank. Be sure the blade/strip is held flat against the work table while drying, and that the bottom of the strip is level with the bottom of the blade. Make an airfoil template from thin cardboard or plastic, and file/sand the blade blanks to shape. It is important to keep all the blades as equal in shape as possible. The more uniform the airfoil the better the

performance.

NOTE: The following paragraph explains how to add carbon fiber strips to the top and

bottom of the blades. If using blades from AeroBalsa, this step is not required. Cut two 15" (1/8" wide) strips of (iron-on) Carbon Fiber for each blade. Mark the strip location at 1/2" from the leading edge, and tack the CF in place with a hot covering iron. Then use thin CA glue to secure the CF strips to the blades on both the top & bottom. Using a small piece of waxed paper (to keep your fingers clean), will keep the strip smooth to the blade when applying the CA glue. The fiber bracing will keep your blades from breaking in-flight. Cut the root-end mounting pads from 1/64 (bottom) and 1/32 (top) plywood, and epoxy in place, using clamps to insure the top pad conforms to the airfoil curvature.

strength as well as insuring that your model stays within the flight weight limit. If you absolutely cannot find the CF stripping, I would perhaps use a 3/16 square spruce spar down the chord balance/bolt line of the blade to maintain adequate strength in the blade. I have not used a wood spar type blade on this model, so I cannot say for sure that it will work as well, and it will be heavier than the original blade, and excess weight is not good. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 8. BLADE BALANCING: It is very important to fully balance the blades. Each blade must balance along the chord line, 1/2" in (aft) from the Leading edge. To do this, insert a thin nail, or piece of wire, in the mounting hole at the root end of the blade, and suspend vertically in line with a door frame or something else known to be vertical, such as a window frame. If you've constructed your blades well, the tip end of the blade leading edge will be hanging toward the rear of the blade slightly. Check and compare each blade using the same procedure. Each blade will require a slight amount of lead weight between the

NOTE: It is highly recommended you do not omit the Carbon Fiber strips for the stabilizer and homemade blades. Using such light & strong material insures adequate

chord line (Carbon Fiber) and the hardwood leading edge, near the tip of the blade. Once each blade is within a degree of vertical, they should be OK in regard to chordwise balance. The blades must be also balanced spanwise, along their length. Using a small dowel, place a blade perpendicular on the dowel & rotate the dowel to "teeter" the blade to locate the lengthwise balance point of that blade. Do this with each blade and mark the point of balance. Ideally, all blades will balance at the identical point along its length. If any mark is more than 1/8" off from the others, insert/glue a bit of lead weight at the appropriate end of the blade to bring it into balance. Note: insert/glue any weight used to spanwise balance a blade, in line with the chord balance line/Carbon fiber, 1/2' in from LE. This slight tip weighting of all blades works very well to improve overall performance. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 9. MODEL COMPLETION: Shape the landing gear struts from 1/16" music wire (5/64" for .09/.10 models), and use small lightweight wheels. Since this model is hand launched, it is needless to use large wheels, with the object to keep the weight low. The very light and inexpensive wheels shown on the plan are fine for most ground/grass flying surfaces. For a hard surface, I found the Dave Brown Lite Flite, small pylon racer wheels, or Williams Bros. 1 7/8" (Vintage wheels #128), work well . There several engines that can be used with this model. The MP Jet .061 (Carlson Engine Imports, Phoenix, AZ.) is excellent (shown below on the left). A Cox .074 (if you can find one) is a good one. The AP Hornet .09 (Hobby Shack) is a great engine, and an OS .10fp can be used if desired. You must adjust your building of this model according to the motor you elect to use. The heavier motor will necessarily have to be mounted further aft than the light ones, and on a stronger mounting, closer to the CG. The smaller, lighter motors need to be forward and can be mounted on a light ply plate. The motor on the right below is the Norvel .061 R/C... While a strong enough motor to power this model, I personally do not like to use it due to the poor muffler installed. The Norvel will spew fuel exhaust on the model. If you can satisfy yourself with exhaust removal with the Norvel motor, it would be suitable to power this model. It is easy to install a short silicone exhaust deflector on the MP Jet .061 shown on the left. The new AP Hornet .09 (Hobby Shack) also appears to be an excellent, if not ideal choice for the heavier version of this model. The MP jet motor is currently available from Carlson Engine Imports, Phoenix, AZ.

Mount the engine with zero degree side thrust, and 5 degrees downthrust. The fuel cell recommended is a 1 ounce, rectangular or round one to keep weight to a minimum. It is possible to use a 2 ounce cell with the .09 or .10 engines Servo pushrods: Use regular 2/56 rods or smaller music wire. Remember, the servo arms on these small servos are very small and cannot accommodate large wire. EZ connectors work very well. DuBro swivel ball links are excellent for connecting to the rotor head, due to the two- axis pivoting of the head. This is the same type link used on helicopters. Normal nylon pop-on/off ball links can be used on these small models if desired, if you insure there is no binding that could cause the link to be "popped" off. Since they are not as secure as the closed links, they are not recommended for larger model autogyros. For the throttle cable connection, use the thin Sullivan #507 control cable, hardened at the ends with rosin solder. Receiver: Use the smallest/lightest receiver you can find. I use the FMA Tetra, or Fortress Micro. The JR 600 receiver is also good due to their small size and light weight. You can also save weight by making your own lightweight switch harness if possible, using Radio Shack #RS 275-407 switches. Receiver/battery installation: The model is balanced when it hangs nose down about 5°-10° when held by the rotor pivot shaft. The small flat (250-270 MAH) battery or the receiver can be installed below the fuel cell or aft of the servos. Depending on how the model hangs, install the receiver/battery to obtain the proper balance. Tail Skid: A music wire of approximately .035 (1/32") diameter works well for a skid that projects down about 1". See the drawing on the plans for completing the skid. Using 1/2 of a normal nylon airplane hinge works well. Insert the wire in the hinge, bend to shape, then epoxy into a slot where shown. There is more stress on a model autogyro at landing than during flight. The desired touch down is a near zero forward and vertical movement. It is not unusual to experience a short drop vertically, thus placing a stress on the fuselage between the rotor and the tail skid. An excellent option is to attach (with CA glue) a narrow strip of Carbon Fiber along the bottom of the fuselage to minimize possible brakeage of the balsa framed fuselage on landing. If you build the model to accommodate the .09 or .10 motor, the aft fuselage will need to be sheeted with balsa/ply and therefore the CF

strip would be purely optional for the sheeted fuselage. If you fear your ability to land softly, install the CF strip regardless of which version you build. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 10. BALANCING AND FLYING: BEFORE attempting flight, and with the fuel cell empty, hold the model up by the rotor hub/shaft. The model should hang nose down at about 5 to 10 degrees. This is commonly known as the "hang angle". This slightly nose down angle is necessary for flight stability and to enable the model to assume a nose down "glide" if the motor fails, giving you a degree of control over the ground impact. Without it, and if the motor fails, the model may become uncontrollable and where and how it lands will be totally out of your hands. Also, if the CG is on or aft of the rotor, the model may be excessively sensitive in roll control. If the model lacks the nose down attitude, place the battery in the forward compartment, or install heavier wheels, etc., to obtain the proper attitude. If the model has excessive nose down attitude (over 10 degrees), install both the receiver and battery in the aft compartment. Complete all balancing with the fuel tank empty. Adjust the fore/aft rotor tilt servo control to allow the rotor to be flat/level (or slightly down in front) with the transmitter stick/pitch control servo in the full forward position. Adjust the aft servo tilting so the rotor will spin no closer than 1 inch above the aft fuselage structure. Set the lateral (left/right) throws to allow 7-8 degrees tilt each side. You will find that the model will react quite well with this amount of lateral tilt. Anything in excess of that may make the model highly "sensitive" and promote over controlling. If the model experiences any problems completing a turn, it will almost always be when attempting a right turn. This is probably because your turn is into the advancing blade, thus your final control throw settings may require a little more right throw than to the left. The rotor rotates counter-clockwise when viewed from the top. You can test the rotor for lateral trim that may be necessary for initial flight. Hold the model with the right hand, just below & forward of the pylon, at a nose high (45 degree angle), and point the nose directly into a breeze. Lightly flip-start the blades with the left hand, and if the breeze is sufficient (5k or more) the rotor should slowly accelerate or at least continue to rotate at a moderate rpm. If the breeze is not strong enough to accelerate the rotor automatically into autorotation, walk slowly into the breeze, maintaining the nose high attitude. The rotor should then accelerate into autorotation. This sudden rotor acceleration is very noticeable, and an increase in lift will be noticed. When you notice this sudden and noticeably high speed RPM, slowly lower the nose to perhaps only 20-30 degrees nose high, while continuing to maintain the high rpm. Now, the model should gain lift and become very light. At this time note any tendency for the model to pull/lift to the right or left. If you do not notice any unusual tendency, leave the lateral trim zero (disk level left/right) for launch. It would not be unusual for a model of this configuration to lift slightly to the right, requiring a couple degrees left pre-tilt trim in the rotor for launch, however most of my models have zero left/right trim

requirements. However if you do experience a definite roll one way or the other, tilt trim the rotor a couple degrees in that direction. Normally if needed this trim is to the left. I doubt if you will ever find the need for a right tilt trim. Set the throttle trim so that you can stop the engine with full down transmitter trim. Do not maintain a 'high' idle trim during landing. It may make it difficult to land the model under zero to light wind conditions (the model will want to continue to fly), therefore you need to be able to slow/stop the engine while landing. For launch, start the engine and walk to a position up-wind where you can point the nose into the wind, and be able to walk into the wind a short distance if necessary. the model to roll to the side before you have the chance to correct. The model will fly in a wind over 10 kts; however avoid this as it may make it difficult to land without damaging the blades due to the wind blowing the model over after/during the landing. Don't attempt to taxi this model, it has no tail wheel, and it can easily blow over with cross-wind. Try to keep the model within 200' distance and watch it closely. Orientation with a wingless gyro can be difficult, and it is recommended you have a helper for the initial few flights. I colored the top of my rotor blades a bright color, and attempt to keep the bright disk top in view. This tells me the model is not going away. If you allow the model to get too far away, orientation will be quickly lost and controlling the model impossible. IF ORIENTATION OR CONTROL IS LOST, first reduce the power!

Important: Always launch directly into a breeze! A cross wind launch may cause

Second, release/neutralize the control stick and allow the model to stabilize itself. You may then be able to re-orientate yourself and continue to fly it. If not,

throttle off and allow the model to settle by itself.

With power failure, you will still have some limited control, depending on altitude. If at low altitude, it is best to release/neutralize the stick, and allow the model to settle like a parachute. Generally it will sustain only a broken propeller / bent landing gear/ and or a nicked rotor blade or two. Approach and land into the wind! Slowly reduce altitude & power as you approach the desired landing spot. With practice you can land at your feet with zero ground roll. Do not allow the nose to get too high too soon. The ideal landing is when you can reach a few inches above the surface with the nose slightly high and at or near zero airspeed. If you find yourself drifting crosswind during the final portion of the approach, it is best to abort the landing and try again. Without a rudder, it is very difficult to correct for the drift with rotor tilt only. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ADDITIONAL NOTES: The carbon fiber stripping is available from Tower Hobbies or Composite Structures Technology (CST) of Tehachapi, California (800-338-1278). CST refers to this particular striping as "Uni-web carbon strips" and/or "tack-on strips". It is also available from "New Creations", Willis, Texas. The roll control lever arm was made from 1/16" rigid fiberglass pc board material; however you may substitute a ROBART 3/4" Ball Link horn (# 331) for this purpose. I do not recommend using plywood. The tiny ball bearings are a key item for this model. Despite their extremely small size, they have proven to be rugged and efficient in several different size models, and I highly recommend them. They (Team Losi # A-6912 XX, 3/32 x 3/16" ball bearings) can normally be purchased at model car hobby shops. A slight amount of hinge separation is necessary for proper left/right tilt operation. The top (rotor shaft part) must be free to flex left/right approximately +/- 10 degrees with little effort. If you use very thin hinge material (non-Polypropylene, such as coffee can lid material of .025") you may reduce the separation slightly too about 3/32" because the larger 1/8" gap may allow excess flexing and fatigue. As an option, the hole (in the pylon sides) for the pitch pivot rod may be "sleeved" with a 1/4" piece of nyrod to make for smoother pivot operation, and extend the life of the head.

(2nd edition: 5-99) Jim Baxter www.autogyro.com [email protected] www.aerobalsa.com

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