Hangar 9

Saratoga 40

A Versatile RTF airplane disguised as an ARF

By: Frank Granelli

The Saratoga 40 from Hangar 9 is one of the newest ARF plus airplanes we have tested to date. The Saratoga 40 is a 40-size (64-inch span) Almost-Ready-to-Fly (ARF) that can be powered by a 40-.52 2-stroke glow engine, or by a .56 to .82 4-stroke engine or by an outrunner “46” size electric motor. After flying the Saratoga with the electric motor, my guess would be that flying this airplane with either a .52 2-stroke or an .82 4-stoke engine would be more in the realm of model rocketry than model aviation.

There will be more on how the Saratoga 40 flies in a bit. For now, let’s look at assembling this ARF Plus airplane. What do I mean by ARF Plus? Basically, I mean that this airframe is actually a Ready-To-Fly (RTF) aircraft that arrives without the radio or power systems. The construction is identical to an RTF in every way. But instead of having to fly with whatever radio and power system the manufacturer supplies, the pilot gets to choose what goes into the airplane.

Photo 1

As part of its RTF heritage (even though there has not yet {hint-Hangar 9} ever been an RTF Saratoga 40 from which to generate a heritage) the Saratoga 40 has the following RTF assembly features:

Ø  All control surfaces are hinged and attached.

Ø  All control horns are factory installed.

Ø  Both the vertical fin and stabilizer feature easy bolt-on assembly.

Ø  The tail wheel assembly is factory installed on the rudder.

Ø  The wing halves slide over two aluminum tubes without gluing

Ø  The servo mounting holes are pre-drilled

Ø  The control rods are factory cut and already bent for servo connection.

Ø  Blind nuts are factory installed for cowl mounting and motor/engine mounts. The cowl mounting holes are pre-drilled

Ø  The pin release for the top hatch is factory installed.

Ø  Blind nuts for the landing gear are pre-installed. There was a problem on this one so read the text.

All of these features are more RTF and are above and beyond what the usual ARF features. Assembling the Saratoga 40 can be performed by anyone in 3-4 hours. The airplane has to come out straight and true as everything was factory aligned. Only three areas require gluing; the windshield with canopy glue, the factory painted pilot with silicone adhesive and the throttle pushrod support with epoxy.

Photo 2

All the major parts are shown in the photo above. Note the assembled tail wheel and the servo mounting holes already drilled. Another time saver is in the lower right of the photo but is difficult to see even when the photo is enlarged by clicking on it.

Photo 3

An enlargement of the lower right corner shows the clear cowl right next to the factory painted version. You do not want to cut that pretty factory painted cowling any more than is absolutely necessary to make room for your engine controls and muffler exit. After the engine is installed, the clear cowling is mounted and all the clearance cuts made. Then, the clear cowling slides over the painted cowling and the cutouts are then transferred to the painted cowling. This saves a lot of time and prevents mistakes.

But since this Saratoga 40 is the electric version, the clear cowling was not needed as there were no cutouts for the electric powered version. While many Saratoga 40's will be built with glow power, I chose electric power because this airplane is going to spend most of its life on floats. The Saratoga 40 has the float mounts built right into the fuselage and includes a float mount adaptor in the box. Even the rear float mount screw holes for the nylon strap holders are pre-drilled. Is there anything that Hangar 9 did not do for the pilot?

By using electric power for the float version, I don’t have to worry about the engine’s stalling far out in the lake. The only boat I have is a blow-up raft so I hope to keep retrieval trips to a minimum. Putting the Saratoga 40 on floats and flying the seaplane version is a second article and will be published shortly in the Flight Tech Section. Look for it.

Photo 4

Photo 4 shows everything needed to assemble the electric powered Saratoga 40. The four servos are JR DS821 Digital Sport servos featuring ball bearing output shafts and high-strength gearing. While weighing the same 1.5 ounces as standard sport servos, these digital servos feature precise control response and have excellent centering far better than any non-digital servo.

The Electronic Speed Control (ESC) is the E-flite 60-Amp Pro Brushless ((EFLA1060). It is equipped with a Battery Eliminator Circuit (BEC) and will power the receiver and up to 6 digital servos (or 7 standard servos). This ESC is fully programmable for braking, timing, start types and voltage cutoffs. The ESC will handle up to 6-cell Lithium Polymer batteries. The ESC even arrives pre-wired for motor connection (I hate soldering motor connectors).

The Saratoga 40’s motor uses 4-cell Li-Poly packs. The 4-cell, 3850 mAh battery used is the new Thunder Power Pro-Power series 30C pack (THP3850-4SP30). I don’t recommend using more cells or a much larger capacity battery for land use as that will cause the airplane to be far too nose heavy. Even with the smaller pack, a little tail weight is needed to balance at the designed 2.75 inch mark. The 3850 mAh pack provides at least 15 minutes flying time, maybe more, and more than enough power for some vertical performance (see the videos).

The E-flite Power 46 brushless outrunner motor is a 670 Kv unit that will run continuously at 40 Amps maximum. Its maximum burst current is 55 Amps while the ESC peaks at 75 Amp Bursts. Turning the recommended APC 13 x 6.5E in. propeller (“E” stands for “electric”) at 7,400 rpm, the motor draws 38.5 Amps at 15.8 Volts while drawing 601 Watts. This is so far below both the ESC’s and the battery’s capabilities (the battery will deliver up to 115A and the ESC up to 60A) that neither gets even warm after a hard, prolonged flight.

Photo 5

Photo 6

Photo 5 shows the very complete hardware kit included with the Saratoga 40. If you are assembling the engine version, there is a complete clamp-on universal engine mount included. The fuel tank and all its parts are also included. Each hardware package is labeled so you can tell where every piece is intended to be used (photo 6).

The engine mount and fuel tank were not used. However, those four long silver hexagons and the even longer bolts located just in front of the pilot were used. These are the electric motor standoffs used to mount the E-flite motor. More on that later.

The Wing

Photo 7

For now, let’s start with the wing. Locate the bag marked “Wing” and put aside the two nylon wing mounting bolts for now. Photo 7 shows the wing exactly as it arrives at your door. The control horn is already mounted and the aileron control rods are pre-cut and already bent to fit into the servo arm. Use the largest servo arm packed in with your servo.

Photo 8

Center the servo with your transmitter and clamp the aileron in the neutral position (see “How To Build An ARF” in the Flight-Tech Section. Check photo 52), drill out the outer most servo arm hole with a 3/32 in drill so the rod slips into the arm without “play”. Screw in the clevis almost all the way. Connect the bent rod end into the servo arm hole and secure with the nylon lock. Repeat with the other wing half. Hangar 9 puts string inside the wing so that the servo wire, with its 6-inch extension attached, can be pulled to the center section and out the corresponding small hole in the wing.

Photo 9

Each wing half slides onto two aluminum tubes as shown. The larger diameter tube is the main spar. The 4-inch long smaller tube is the anti-rotation bar that insures both wing halves have the same incidence. The halves are not glued together. While the wing-to-tube fit is tight and without flex, they are not so tight that they cannot be easily removed. This allows transporting the 64-inch wing in two pieces should your transport vehicle not be a semi-truck.

However, if you can keep the wing together, put a short piece of transparent tape over the wing center section locking the haves together. Otherwise, you might lift one half of the wing, hold it vertical as we often do with one-piece wings, and suddenly find the lower wing half parting company. The wing tip you save might be your own so tape the halves together if you can.

It requires about 30 minutes to complete the wing if you don’t rush it. Maybe 25 minutes if you do. But this is such a relaxing and fun airplane to assemble, treat yourself to a little luxury and take your time.

The Fuselage

Photo 10

Now is the time to assemble the two glued parts used in this airplane so they can be drying while the assembly is completed. Using RC 56 or canopy glue, glue the windshield in place and tape it down using low-tack masking tape. Before you glue the windshield, note that the canopy release lever is located right in the center of the dashboard. Make sure there is enough “finger” room to reach it to pull it rearwards after the canopy is installed. The instruction book covers this well.

Use either silicone adhesive or Zap a Goo to keep your pilot on the job if your Saratoga 40 is glow powered. However, since this one is electric power without vibration, I just used some 5 minute epoxy. Use tape to keep the pilot from going UA (Unexplained Absence) until your adhesive dries.

Photo 11

While the hatch is drying, start on the fuselage. Note that all the servo mounting holes have already been drilled. Even better, these holes are through a reinforced servo tray. Hooray, at least Hangar 9 understands that 1/16 plywood trays require reinforcement of the servo mounts over hundreds of flights. This tedious reinforcement job has been done for you. Way to go Hangar 9! Install two or three servos into the tray depending on your power system.

Photo 12

Photo 13

The tail feathers bolt onto the wide, study plywood fuselage stabilizer saddle. First, use some thin CAA and put some into the stabilizer holes, and in the fuselage mounting holes as shown. This reinforces the hardwood to prevent future loosening after several hundred flights. This airplane flies so well and is so easy to fly that yours will last at least several hundred flights. Probably, you will find yourself wearing out several engines or motors during this aircraft’s life span.

Photo 14

Photo 15

After the CAA has cured, insert the two “bolts” that extend from the vertical fin through the matching holes in the stabilizer until the vertical fin is resting tightly on top of the stabilizer. Then insert that assembly into the matching fuselage holes completely. There should be about 1/2 inch showing on the fuselage bottom. Insert two washers and the two lock nuts as shown. That accounts for the tail assembly in about 5 minutes, including time for the CAA to cure.

Photo 16

Use a pin vise (the small hand drill model railroaders really love) to drill a 3/32 hole in the outer servo arms as shown. Slide the two pre-cut and bent control rods through their respective installed nylon guide tubes NOTE: the shorter, 23-inch rod goes to the elevator. The longer 23.5 inch rod fits the rudder.

Photo 17

Photo 18

Install the elevator clevis onto the control rod almost to the bottom. Note photo 17 carefully. The control rod rests just inside the control horn as shown. You do not have to bend this rod. In fact, leave it that way. When you attach the clevis, make sure that the pin-mounted side is on the outside of the control horn (photo 18)

Photo 19

Then push the pin through the control horn and lock the clevis in place. Slide the small piece of fuel tubing provided over the clevis to lock it. The reason to position the pin-mounted clevis side outside the control horn is so the rod continually pushes the clevis pin into the control horn. This can’t ever come loose even when, not if, the fuel line keeper breaks off. Do not, ever, depend upon a fuel line keeper to lock your elevator clevis to its control horn. These keepers often break under years of fuel soaking and the stresses of hundreds of flights. Use the keepers of course, but do not depend upon them. Check them often and replace as required.

Do the same with the rudder. Connect the control rods to the servos. Make sure the elevator and rudder are centered with the transmitter trims in neutral. Use the transmitter’s sub-trim feature to make the final, very small, centering adjustments.

Photo 20

Now that the tail is complete, move to the front end. Need a blind nut anyone? The mounting blind nuts for both the electric and glow-powered versions are both factory installed. If using the electric-power version, punch out the two cooling holes as shown. Otherwise, leave them in place for glow-powered airplanes.