 |
Web Hosting by Netfirms | Free Domain Names by Netfirms |
|
|
|
Building Tips and Tricks
When you are deciding to build your scale model, you will have many kits and manufacturers to select from. You will also notice that not many of them are sold as Control Line Models. Brodak seems to have the largest supply of CL planes. But, don't let that throw you. RC kits have great detail and are easily converted. Finding kits in the 40 size and converting to Carrier is not a problem and the selection of airplanes is greater, with RC kits.
After you have selected the plane you want, build the RC kit the same as you would as if it were going to be RC . Build according to the instructions and plans that come with the kit. You will need the Servos, Battery Pack, pushrods, clevis and linkages, the same as you would for RC flying and hook up. Try not to mix your servos. Maintaining consistency is important. If you need to mix servo types make note of the polarity. (information on servo connection). You will need a NYLON or COMPOSITE Plastic Bellcrank, for the Elevator control (in the smaller airplanes and Metal or aluminum for the larger planes. Instead of connecting the Elevator to a Servo, you will be connecting it to the Bellcrank, with lead out wires, or stranded cable that exits the left wing tip. (lead out information). The Elevator is the only manual control for the airplane, when you use the ScaleMaster Operating System. You will also need some "weight" (about 1/4 oz to 3/4 oz) in the right wing tip. If you are going to use Rudder and Ailerons make sure that they are configured for "R" right bank and Right Rudder only, and functional at lower speeds, with 0 deflection at high speed. Don't over due the tip weight..remember it is only to counter line drag on take off. If it is going to be a Carrier Airplane then make the wing a permanent installation, rather than removable.
Make your Wing Flaps, Retract Gear and Throttle the same as you would for
RC. If you have a military plane, you can also get scale looking bombs and bomb
racks. Follow the directions for installation according to the products
installation instructions and connect a servo for their operation. Use Micro servos
for the "non" stress or non pressure controls, such as throttle.
The ScaleMaster "Medallist" has 3 Toggle Switches, 2 Push Buttons and 1
Proportional Lever control to handle your function operations. Flaps, would be done
by the Proportional Lever control..while Retracts would be a Toggle Switch operation and
Bomb Release would be a push button. Retract Servos are available from all of
the major RC manufacturers...choose the one that is best for your plane (space and
movement). We use the HiTec Low Profile Retract Servo. There are Linear Servos
as well for tight areas. You might also use Air Operated Cylinders for retracts, in
the larger planes.
With some imagination you could design your own assembly to make Sliding Canopy, moving Gun Turrets, Bomb-bay Doors, etc. I even know of one pilot who is making his Scale Pilot so that he waves to the spectators. Don't be afraid to go on line and seek advice or talk to your local hobby shop. In California, the Los Angeles area, you can contact "Robin" or "Ray" at Robins Hobbies 1822 West Glenoaks Blvd. Glendale, CA 91201 (818) 240-2093. Robin's carries a full line of products for RC Kits that can be converted to CL as well as RC Cars and Helicopters, and if he does not have it in stock he will order it for you. The service in Robin's is excellent and they are always willing to help the novice builder/pilot. A Local Flying Club in your area is also a great place to share information and get help.
There is no limit to what you can do. You are only limited by your
imagination. Here is an example of how to make engine "cowl (cooling)
flaps" operate in proportion to the throttle control. The flaps open to allow
more exit of hot air, at low speeds. At high speed the flaps are closed and the
natural venting curvature at the firewall serves as the hot air exit. This is
because at high speed allot more air is forced past the cylinder head than at low speed,
so the opening does not have to be as large.
The illustration below uses the P-51 Mustang fuselage and engine cowl outline, however,
this is NOT the scale position of the cooling flap on the mustang. The scale
position is at the aft end of the intake scoop, on the bottom of the airplane.
Routing a scale duct for a flying model (of the mustang) is very difficult, simply
because of the way model construction is done. Making a scale flap work on a mustang
model is not hard, but making it functional is. See the "Scale"
section Philip Avonds mustang (rear view) for the actual flap location.
The Corsair or other radial engine airplanes do have the cowl flaps at the rear of the
engine cowl. There are more cooling flaps for radial engines, from lower third 6
panels for the Thunderbolt to 7/8th of the diameter of the Corsair.
The bracket for the control horns, in the case of this illustration, would be made of 1/16" x 1/4" aluminum bar stock and the length made to fit the size of the engine. The control horns, themselves, are made from thin brass bar stock, or double folded coffee can, tin. The axle is made from 1/8" piano wire. There are 2 flap actuator arms, one on each side of the cylinder head, and a throttle horn located in line with the throttle arm on the engine carburetor. All of the arms are silver soldered to the axle in the proper position. And then the whole assembly is mounted with the screws from the engine back plate.
The Cowl Flaps are made from coffee can, as are the tabs for the push rods. The flaps are hinged, with piano wire and coffee can, in the center of the flap section, while the push rods come down off of the control horns on each side. You can use "small" nylon clevis connectors for the push rods, or "Z" bends. The actuators push on the outside cowl flaps and the and the center flap is brought down in proportion with spreader fins, on each side. In the animation above, it shows an aileron style ball link. This method is best as opposed to splitting the push rods as illustrated below. Also, the vertical control horn, on the axle, is longer than the flap horn. This differential is needed so that the flap does not become a "dive brake" under your fuselage.
(click for larger view)
No matter which flap configuration you use (simple single section center flap or 3 flaps with center section spreader fins) the overall parts are the same...It's only the location of the arms that would change. (Parts are illustrated above)
A single flap in the center of the cowl
is much easier to build and is very effective. However, this can make the flap over
size for the airplane that you are building, or, be non scale if your airplane requires
multiple flaps.
Make sure that you get the proper alignment of the arms, before you silver solder them to
the axle. Measure and then measure again. Also, make sure there is enough
distance between the axle and the Bracket back, to allow for the Hex head or Allen Head
screwdriver, once the axle is soldered in place. Replace the crankcase screws with
screws that are 1/16" longer than the ones you took out, making sure that the threads
are the same. Use lock tight or silicon to seal them in.
Yes, this is a tight fit. But the added cooling that this provides is well worth the effort. Be patient. Not shown in the illustrations is the exhaust manifold. You will need to do the mechanics around the exhaust. The Throttle Arm should be a straight shot, depending on the size of engine. If not, a gradual bend or a lazy "Z" bend in the arm to compensate for corners is okay, as this is a non-pressure operation, and the bend should handle it fine.
As you progress, your skill in building and flying will improve and your choice of airplane will no longer be limited to single or double control or semi-scale or fixed gear models. Multi-function is the way of the future and the ScaleMaster CL Operating System will be leading the way. Before too long, you will be doing your own designs for linkages.
SCALE STRUTS (tip)
Figure 1 is a standard Robart Scale Oleo (strut) Cover. Although, they have a great amount of detail and add a more realistic look to your gear, they are not true scale. If you are building a "Fun" Scale model, then by all means use the struts as they come, in the stock configuration. Using the cover on a "Stand-Off" or "FAI" Scale model, could hurt you if the judges look closely enough. For larger size planes, functioning struts from BVM, Robart or other company is far more practical for shock absorption on landing. The above scale gear covers work well with Hobico mechanical retracts for 40 and 60 size planes.
Most airplanes, in the fighter category, due not have the (drag) torque links (scissors) above the tire, on the main gears. The "scissors" are generally within the same diameter as the tire and fit into the wheel well. Nose Gears, do have the scissors above the tire. The exceptions to this rule are the airplanes that have "offset" oleos. That is, that the oleo is directly over and center line of the tire, rather than along side of it. An example would be the gear on a P-51 Mustang. Check documentation carefully to find out which type gear is right for the plane you are building.
Check your documentation completely to make sure how the strut is configured on the real airplane. With a little modification, you can get a more realistic strut and also use it to actuate the Strut Door.
Figure 2 shows a modified strut. I use 2 sets of struts to make 1 realistic pair. First I cut away the "hub" below the scissors, above the axle. I trim out the plastic to allow for the Piano Wire to accommodate the bend for the axle. I fill this in with Bondo and shape it to scale. This brings the scissors down to the approximate scale position. Next I fit the Wheel Assembly and Tire over the axle and mark the top of the tire on the strut cover. This mark is used as the bottom mark line for the scissors portion. Next, I take the 2nd pair of struts and cut the scissors portion away from the tube. Then cut the oleo cover so that the scissors portion fits, matching the bottom of the portion on top of the line I made. Then replace the upper part of the strut cover. The Scissors portion is placed at a 90o angle to the Wheel. Fill in any miss matched edges with balsa filler, Bondo, or epoxy.
Make a Gear Door pushrod from a piece of small brass or copper tube. The inside diameter should be just large enough to insert a cotter pin in each end. Silver solder the assembly together. The hole you drill in the 2nd scissors top, should be large enough to accommodate the hub screw that comes with the struts. Insert the pushrod in the trimmed out area and thread in the screw. Coffee can works well to make the doors and door bracket hinge and pivot hinge.
There are many CA glues, out there, that you can use. But the one that I have used for over 30 years, I feel is still the best and was the first and original CA glue, is Satellite Citys' "Hot Stuff" and Accelerator. Although, there are many CAs, ZAP to SuperGlue...There is only one Satellite City and only one Hot Stuff. Zip Kicker also works very well as an accelerator for hot stuff, in addition to any other CA glues. These glues do give off a smell and fumes that can be hazardous. Make sure that you use them with good ventilation. Also, take care to make sure you are not allergic to CA before you use any of this type product. There are other glues that were used before the introduction of hot stuff and those glues are still around and are very adequate for your building needs.
Thin is
the Red Label and Gap Filling is the Yellow. Use on all Balsa and Some
Hardwood surfaces. Use Accelerator first on the hardwood to prep it...Use Epoxy on
Hardwood Engine Mounts and Landing Gear Rails.
The Accelerator can be gotten in small bottles, with a pump action spray head, and larger
bottles for refilling.
Thin dries fastest, gap filling is slower. Use kicker sparingly.
Click on the Images for a great source with fantastic prices.