Futaba 7C 7-Channel FASST RC System

The new Futaba 7C 2.4 GHz FASST RC System is one of the latest additions to the very rapidly expanding list of 2.4 GHz airborne radio control systems. We as modelers know Futaba as a leading manufacturer of radio control systems for model cars, airplanes and helicopters. However, Futaba is actually one of the world’s largest manufacturers of all types of electronic control systems for a wide variety of industries.

Futaba has been designing and making 2.4 GHz industrial electronic control systems for many years. During that time, they have gained a reputation for innovation and problem solving. Within the past two years, Futaba has turned their 2.4 GHz design expertise loose on the RC hobby world to the modelers’ benefit. The new 7C FASST RC System is the latest example.

For those who are not familiar, or only vaguely acquainted with 2.4 GHz, maybe a few descriptive words are in order. Note: This is a very non-technical section designed only to point out the 2.4 GHz systems’ differences / advantages. All you radio technicians out there, thank you for all the great stuff you have given us but don’t expect anything even close to engineering here.

2.4 GHz RC systems work on two entirely different principals from our “conventional” RC radio systems. First, systems like the FASST transmit their signals on 2.4 GigaHertz frequencies instead of on the 72-75 MegaHertz band (72 MHz band for airborne models) or the 27 MHz frequencies that we have used for the last 40+ years. In itself, this would make most of us think, “Fine…whatever”. We really don’t care about what radio frequencies are used as long as our signals get to the airplane and are understood.

While that is true for most of us, utilizing the 2.4 GHz band has several serious benefits for us, the “common” pilots:

Ø       Using the 2.4 GHz band means that each transmitter and receiver can utilize a special code. Once bound together, the receiver will translate signals only from its own transmitter. All other signals, even ones on the same frequency, are ignored. This about eliminates interference “shoot downs” from other transmitters. The Futaba 7C also features something called “Pre-Vision Screening” that further prevents the receiver from responding to unwanted 2.4 GHz signals. Just to make sure what Pre-Vision Screening was all about (as a former marketing guy I know better than to go by names alone), I contacted Futaba’s technical service and got this response:

Here is  ”what Pre-Vision is, does and why it is important.  First of all, only Futaba is able to offer our modelers Pre-Vision as they have patented the technology (# 6,141,392). That is, no other radio manufacturer, or firm, can match this unique feature.

As the receiver receives the signal from the transmitter Futaba’s Pre-Vision seamlessly scans the incoming data and applying a very sophisticated error correction technique. This eliminates any errors or difficulties and provides the modelers with a solid, impenetrable link with their aircraft.”

Ø       The transmitter simultaneously transmits information using either one or two frequencies (or pipelines as the engineers say). The pipelines may be redundant or may be carrying separate information. There are 80 pipelines (frequencies) allocated to all types of RC control so many transmitters can be operating at any one time; without interference.

Ø       For technical reasons none of us are yet old enough to know, many 2.4 GHz transmitters produce a shorter latency period. The latency period is the time from when the transmitter stick is first moved until the servo starts to obey the command. This means faster servo response and a tighter piloting “feel” for the aircraft. While not apparent when flying most trainers, a short latency period is readily noticeable flying sport aerobatic airplanes.

Ø       Many 2.4 GHz transmitters, all the FASST Systems included, frequency hop through the 80 channel RC range. Futaba calls their frequency changing feature “Channel Shift”. Hundreds of times a second, the pipeline changes frequency. Even though the frequency is constantly changing, the FASST system will never interfere with other 2.4 GHz RC systems in use.

Ø       Metal to metal radio noises, a big problem for helicopters that can cause 72 MHz systems nightmares, find it so difficult to affect 2.4 GHz systems as to make such interference nearly impossible.

The second advantage is the way 2.4 GHz operation is managed in this country. In its regulations, the FCC strongly suggests, to the point that it is nearly a requirement, that all 2.4 GHz transmitters, RC systems included, must look ahead to find an “open” frequency before transmitting on, or hopping to, any 2.4 GHz frequency. Therefore, if one transmitter at the field is already using a frequency and then a second transmitter is switched on, the second transmitter will not transmit on, or hop to, the frequency being used by the first transmitter.

 

As each additional 2.4 GHz system is employed, it follows the same routine; skipping the frequencies already being used by other transmitters. Futaba’s “Channel Shift” protects all users on 2.4 GHz regardless of who manufactured their RC systems.

Ø      Therefore, no RC 2.4 GHz transmitter will be using the same frequencies as another at the same time. This means that it is impossible for one RC 2.4 GHz transmitter to shoot down another transmitter’s airplane.

Since identity codes and frequency protection are both active, losing your 2.4 GHz airplane to interference is made about as impossible as it can be. In these days of Park Flyers and mass market-purchased airplanes that are operated anywhere, including near your club field without your knowledge, having a 2.4 GHz system is almost required protection.

Photo 1

OK, let’s get off the 2.4 GHZ bandwagon and take a look at the Futaba 7C FASST System. The heart of this system is its T7C transmitter. This 7-channel transmitter is almost identical to the very popular Futaba T7CAP transmitter except that it sends out its signals on the 2.4 GHz band instead of via Pulse Code Modulation (PCM) on the 72 MHz frequencies. The T7CAP transmitter is a 1024 unit meaning that its servo control is extra precise. Since the 2.4 GHz T7C unit is based on the T7CAP, it should also feature 1024 precision.

The transmitter can be optimized for fixed wing airplanes or for helicopters. This review will deal mainly with the System’s airplane application but a single, quick software switch makes this System heli-ready.

Photo 2

The T7C, and the T7CAP, transmitters belong to the “Intermediate” class of transmitters. Today’s computer transmitters fall into four basic classes, depending on cost and capabilities. The first class, we’ll call it Basic, have limited capabilities. Most are 4, 5 or 6-channels and can perform low-level computer trimming functions. The Basic transmitter’s functions most used are:

Ø       Servo reversing

Ø       Sub-Trim (setting the neutral point)

Ø       End point adjustment (expanding or limiting servo travel at full control deflection)

Ø       High/Low adjustable servo travel rates on elevator and ailerons (sets the airplane’s control responsiveness)

Ø       Exponential on elevator and ailerons (sets the airplane’s control sensitivities)

Ø       Some feature Aileron Differential (adjusting aileron movement to reduce adverse yaw)

Ø       Flaperon setting (allows using a servo for each aileron and/or using ailerons for flaps)

Ø       Limited flap to elevator trim adjustment

There are a few other Basic features such as elevon settings, delta aircraft use this setting as their ailerons also function as elevators and fixed rudder-to-aileron mixing for pilots still learning that their left hands move sideways as well as up (high throttle) and down (low throttle).

Basic computer transmitter RC systems usually sell in the $170 to $230 street-price range. Many of these transmitters are supplied with today’s Ready-To-Fly airplanes. Many systems usually also feature a 6-channel receiver to make use of the flaperon, V-tail and elevon functions.

Intermediate transmitters have 7-8 channels for greater flexibility. These transmitters have all the Basic features while also using more advanced, programmable mixing. Most also allow Exponential and Adjustable Rates on the rudder. The T7C FASST transmitter has both these latter features.

The T7C FASST System has several more features, some not common on Intermediate transmitters (marked with a +). The T7C’s “beyond Basic” features are:

Ø       Three programmable mixing functions. The pilot can mix any channel with any other and then adjust the mix rates. This is especially important for preventing knife-edge walking by mixing rudder to elevator (a very important trimming function).

Ø       Fully adjustable and programmable Snap Roll switch and servo settings.

Ø       Since all the trim “levers” are digital, the T7C also features an adjustable engine cutoff switch (+).

Ø       Auxiliary channel functions (Ch 5 – 7) are programmable to any switch or to none if they are to be operated only by the programmable mixing function (+). Several functions can even be assigned to the same switch but all will be operated to their preset movements simultaneously when that switch is thrown.

Ø       Preset Elevator to Flap mixing. This moves the flaps downwards when “up” elevator is inputted and flaps upwards (above the wing) with “down” elevator”. The results are CL stunt-like square loops, very tight turns without stalling and other interesting, 3-D like maneuvers.

Ø       Ailevator function (+) for matching twin elevator servos. But this function goes one step further by allowing the separate elevators to also function as “ailerons” such as those used in the full-size F-14 Tomcat. Not only is this function unique to the T7C transmitter, the T7CAP transmitter does not have it, but this is the first time I know about having this pre-programmed function on any but the most very advanced systems.

Ø       An Airbrake function (+) used for setting “crow” programming that lowers the flaps while raising the ailerons for extra drag and near vertical descents. The Airbrake can be activated by either a switch or by throttle settings.

Ø       Adjustable trim “lever” sensitivity (+). The pilot can set each control’s trim button to move a lot per step, gross trim changes used for first flights, or a little for those final , very sensitive trim settings.

Ø       The dual, or even triple, rate controls can be set to one switch per control surface or all controls rates put on a single switch. In fact, this transmitter has programmable switch controls for just about every function.

Ø       The T7C transmitter retains memory settings for 10 aircraft. Each aircraft’s name can be set up to 6 characters.

Ø       The T7C transmitter also has a model copy feature that allows copying the programming from a model in memory to another memory model. This is used to setup “Flight Modes” to re-trim an airplane for various weather conditions.

All these capabilities can seem complicated. Actually, the transmitter’s 72 x 32 LCD computer screen makes it fairly easy to move through the various mixing and trimming functions. What Futaba calls “Dial N’ Key” programming is actually a rotating wheel and four-way cursor movement. This combination does make it easier to scroll and jump through the menus. The illustrated instruction manual covers everything in detail with a programming example for every function.

The real key to best utilizing this FASST System is to know what functions you will need for an aircraft, and then use the instruction book’s examples to dial them in for your airplane. After looking at the rest of the System, we’ll program and trim an actual intermediate, sport airplane (advanced trainer) called the TAMEcat 40 from The World Models (available through Airborne Models http://www.airborne-models.com/ ).

Photo 3

The R617FS 7-channel receiver contains two antennae. Since all 2.4 GHz receiver antennae must have each antenna 90 degrees offset from the other, the R617FS’s are preformed to this configuration. For best reception, the antenna should be kept fully “extended” as shown. Most of the antenna is just connecting cable. The actual receiving portion comprises only the short, uncovered section near the tip. This light weight, just 0.34 oz., unit is 1.64 in. long, 1.08 in. wide and 0.36 in. thick. It is light enough for all but the tiniest indoor aircraft and will fit just about anywhere inside an aircraft. The receiver draws very little idle current, just 80 mA.

While the R617FS is a 7-channel receiver, that only applies if it is installed in an electric-powered aircraft that is using an Electronic Speed Controller equipped with a Battery Elimination Circuit (BEC) or if the final, seventh servo is wired, along with the receiver battery, into the Channel 7 receiver port with a “Y” cord. In the BEC example, power for the receiver and servos comes through the throttle channel. But if a separate receiver battery is to be used, in larger electrics and all glow/gas applications, then the “Y” cord must be used for the battery connection.

 

However the battery is connected; make sure that the two antenna wires are positioned 90 degrees relative to each other. The FASST R617FS receiver has some selective circuitry that constantly monitors the signals being received by both antennae. This circuitry then directs the receiver to use whichever signal is the strongest. Having the two antennae at 90-degree angles insures that the antennae “see” different signal “pictures”; presenting the receiver’s selective circuitry with the clearest signal strength choice.

 

Here is a useful little inside tip although this was not done on the TAMEcat. Futaba’s FASST system antennae, complete with extension wires, are about six inches long. It is usually possible to extend one antenna outside the fuselage for an even stronger signal reception. Treat the exit point as you would a 72 MHz antenna wire. Keep it away from exhaust residue and in a place not usually handled. Do not place it between the metal landing gear legs. Only the FASST systems allow outside antenna placement because of the extra antenna length.

Photo 4 

The system can be ordered with one of three servo choices. The standard servo choice is the S3001 ball-bearing servo. This servo produces 41.7 oz-in of torque, good enough for most sport models up to about a 6-ft. wingspan, and requires only .22 seconds to travel 60 degrees. A lighter, slightly more powerful servo, the S3004, produces 44.4 oz-in of torque and weighs 0.28 ounces less.

But the real choice for this System is the Futaba S3152 Digital servo. While it is more powerful, 69.4 oz-in of torque, the real advantage is its extreme precision that matches the transmitter’s 1024 resolution. The digital servo centers more consistently, a must for aerobatics, and offers greater precision at all points. A digital servo makes the best use of a 2.4 GHz system’s short latency period. This would be my servo choice when getting a 7C system and this servo is available for both helicopter and aircraft systems.

This System is also available without servos. “Why” is unsure because the system with servos costs only $20 more for four S3004 servos and just $50 more for four S3152 digital servos. Try purchasing four S3004 servos for $20 and see how far you get. The S3004 servos are $13 each and the S3152 servos are $30 each at discount. Even if you want or need to use different servos from those included in the System, get the servos anyway. All RC pilots will need extra servos at some time in the future and S3004 servos at $5 each is a bargain way too good to pass up. The same applies to the $12 digital S3152 servos.

  

Photo 5            Photo 5A

The instruction booklet takes the pilot through programming step by illustrated step. It uses specific examples for each function. Not only does it show how to accomplish certain mixing functions but then expands the subject to include how to adjust or trim each function.

Photo 6

The World Models (TWM) TAMEcat 40 was the first “fightrainer”, an RC trainer designed to resemble a scale fighter aircraft, ever introduced. Jeff Troy, editor of Park Pilot magazine (http://www.parkpilot.com/), designed the TAMEcat back in the 1990’s. TWM now offers this airplane as an ARF. In fact, Sport Aviator will be reviewing this model in the near future.

Photo 7

In addition to its own article, we used the TAMEcat 40 to test the Futaba 7C 2.4 GHz RC System. The TAMEcat 40 is capable of some interesting aerobatic performance even though it is a trainer. But to make full use of its abilities, the pilot will have to do some mixing and trimming.

The installation was pretty straight forward. Note that the twin antennae are placed exactly 90 degrees apart. Two small pieces of transparent tape hold them firmly in this position. 2.4 receivers can be sensitive to the aircraft’s attitude as “seen” from the transmitter’s position. Placing the antennae at the 90-degrtee point minimizes the affects of the airplane’s attitude.

Note that the actual signal receiving antenna, the bare wires at the ends, are completely free of all obstructions. The ends are kept free of the wires especially. Conductive surfaces can interfere with 2.4 GHz signals. The reduction in signal strength is not usually a factor, but it is a good idea to keep wires away from the antennae on all 2.4 GHz setups.

Except for the antennae placement, all other installation tasks are the same for a 2.4 GHz system as for a conventional 72 MHz one. Once the RC system is installed, it is time to setup the controls. Here is where the 7C system starts to shine. Center the trims and turn on the RC system.

  

Photo 8         Photo 8A

The first setup step is to manually adjust all control surfaces to the neutral position with the trims centered. Sometimes, it is difficult to get a particular control surface in the exact neutral position. One half turn of the clevis moves the aileron too high but going a half turn less means it now is too low. The T7C transmitter’s sub-trim function takes care of this. As photo 8 shows, final trimming both ailerons to neutral meant lowering the right aileron by 32 points and the left by 52. Such a mismatch is very common when setting up twin aileron systems.

The sub-trim function is accessed, like all the T7C’s basic functions, by pressing the Mode/Page button once. Advanced trim settings such as mixes, flaperons and “hard wired” settings are accessed by pressing the same button one more time. Once on the desired menu, use the rotating button to scroll to the desired function and then press it to access that function. This is a very easy way to move around a function list menu.

Photo 9

After all controls are centered, it was time to setup control movement. Use the End-Point function for that. This makes throttle setup so easy that no engine should ever be misadjusted when using this System. Note that high throttle travel was reduced to 93% and low throttle to just 65% of full travel. The 65% low throttle setting set the idle at 2,200 rpm when the throttle trim was centered. Bring all other control surfaces to recommended travel settings.

  

Photo 10          Photo 10A

On high rate, the TAMEcat used 30% exponential for a soft feel around neutral, great for slow and point rolls. But the ailerons still travel to their maximum distance if the control stick is moved all the way. That is essential for snap rolls, spins and stall turns. On low rate, exponential was reduced to 20% since aileron travel was reduced to 75% of full travel. The T7C transmitter features dual rate / exponential settings on elevator, aileron and rudder.

Frankly, I no longer use low rate settings. Instead, I set the exponential rate high on my competition aircraft, ~45% for ailerons, 70% for rudder and ~40% for elevator. This provides the gentle feel of “low rate” during regular flight yet retains full aerobatic potential. I am just not smart enough to remember various switch settings during a competition flight.

If the dual rate function is assigned to switch “G”, it is possible to have triple rates. “G” is a three way switch. Assigning one of more channels’ dual rate functions to this switch converts it (them) to triple rates. One, two or three channels can be assigned to “G”. If multiple channels are assigned to the triple rate switch, all assigned channels switch rates simultaneously.

Photo 11

Back to the TAMEcat 40 setup. The T7C transmitter features digital trims on all 4 major channels. This is a nice feature as the transmitter always remembers the trim settings for each model in its memory. But a digital throttle trim makes engine shut down less than convenient. The T7C uses an engine shutdown setting on switch “B”, or on any switch the pilot chooses. The throttle cut is set after setting the idle. Set the amount of servo movement that will completely close the carburetor barrel from the idling position when switch “B” is deployed.

There are also fail safe functions, servo reversing (used a lot on the TAMEcat 40), trim sensitivity settings and a timing function in the Basic menu setups. The trainer switch activator is also here. Why isn’t the trainer switch not always activated? The T7C’s programming allows the pilot to reset the spring-loaded “trainer” switch to be a snap roll switch that activates all control surfaces when performing a snap roll.

  

Photo 12        Photo 12A

The advanced menu’s most important function sets up the flaperons. Whenever an airplane uses two aileron servos, it is possible to configure the ailerons as flaperons. Flaperons are simply ailerons that also can be lowered to act as flaps for extra lift and drag. Having flaperons also allows the pilot to set varying aileron differential, the upwards moving aileron travels further than the one going down. This matches the drag on each end of the wing; especially on flat-bottomed airfoil like the TAMEcat 40’s, and helps eliminate adverse yaw.

The TAMEcat 40 required 20% differential to eliminate adverse yaw at slow airspeeds. This airplane has so much lift that it could fly at less than 10 mph. The differential really improved handling at low speeds. The airplane liked a maximum flap deployment of 25%. The T7C allows the pilot to make these fine adjustments based on test flight results. Use the flap-trim function to set flap travel.

There are three programmable mixes in the Advanced Menu. These mixes are primarily used to trim an airplane for aerobatic flight. Aerobatic flight is difficult enough without having to fight the airplane through maneuvers. The trimming goal is to have the airplane fly in whatever attitude a pilot places it without needing compensating control inputs.

   

Photo 13         Photo 13A

For example, the TAMEcat 40, being a trainer, will not fly straight in knife edge flight. Maximum rudder application while in knife edge makes the airplane pull towards the “belly”. Using the first mix function, rudder input also causes the elevator to move upwards. Left rudder required 30% “up” elevator for straight knife edge flight while right rudder only needed 17%. Left rudder usually requires more elevator input.

In aerobatic airplanes, excessive elevator mixing means the airplane is probably tail heavy. Adjusting the CG will reduce the amount of required elevator mixing allowing the mix function to only do the “fine tuning”. In trainers however, it means the airplane has a flat bottom shoulder wing and changing the Center of Gravity (CG) will have very little effect.

Photo 14

Like all trainers, the TAMEcat 40 also has roll coupling. The airplane banks in the direction of rudder input. Roll coupling increases the pilot’s workload during slow rolls and stall turns. To prevent unwanted banking during rudder-dominated maneuvers, the TAMEcat 40 needed 12% opposite aileron for left rudder and 9% to prevent a right bank with right rudder.

Photo 15

The TAMEcat 40m did not require the third mixing function but it is there if it ever does. Trimming the airplane for the lowest possible pilot workload is why the programmable mixes exist. But the T7C transmitter also has some “hard wired” trim functions. The Flap-Elevator mix automatically resets the elevator to compensate for any attitude changes induced by flap deployment. The TAME cat 40 needed 15% “up” elevator (you would be surprised how many models require “up” with flaps) to maintain level flight with flaperons deployed.

Photo 16

But the T7C also has an Elevator to Flap function that makes the airplane respond like a CL Stunt airplane. The flaperons go down with “up” elevator and vice versa. The TAMEcat 40 can perform some fairly exciting maneuvers when the flaperons raise upwards 50% as “down” elevator is inputted.

There are other “hard wired” mixing functions that many pilots will appreciate even though the TAMEcat 40 didn’t need them. Scale pilots will love the aileron to rudder mix that performs automatic coordinated turns. Pilots flying scale aerobatic airplanes such as Edge 540’s, Extras, and Caps will want to use the snap roll settings for precise outside snap rolls (inside snaps are usually hand flown by these pilots). Most of these airplanes, and larger scale aircraft, use separate elevator servos and pilots flying these aircraft will love the Ailevator mix that matches servo movement so the elevators both move the exact same amount.

The Futaba 7C RC System is also helicopter friendly. A complete helicopter instruction section details how to best setup and use the 7C for rotating wing flight. While I am not a qualified helicopter expert, (heck, I can barely fly the things so far), the 7C’s helicopter capabilities seem to fit almost every helicopter setup and trim requirements. Here are some of the 7C’s helicopter capabilities as detailed in the instruction booklet”.

Ø       Swash to throttle mixing helps helicopter pilots keep their rpm steady

Ø       Governor select makes it possible to match rpm/blade speed to maneuvers

Ø       3 programmable mixes

Ø       Throttle curve (5-point normal, idle up 1 & 2)

Ø       Pitch curve (5-point normal, idle up 1 & 2)

Ø       Revo mixing

Ø       Gyro mixing

Ø       Hovering throttle

Ø       Hovering pitch

Ø       Throttle hold

Ø       Trim offset

Ø       6 swash plate set-ups (5 CCPM options)

In addition to all the T7C’s special airplane and helicopter abilities, the transmitter has all of the usual amenities like adjustable stick length and spring tension, a 600 mAh Sanyo Ni-Cd battery for at least 1.5 hours of operation, mode adjustment (supplied as mode 2 but can be changed to modes 1, 3 or 4) carry handle and a supplied neck strap.

Summary

If you came to the flying field 30 years ago with this extremely capable RC system, you would probably have either been burned as a witch or besieged by modelers trying to buy it from you. But even today, this is an unusually capable RC System that sells for only $300 street price (S3004 servos). The cost puts the 7C FASST System right in the center of the Intermediate system price range. However, the 7C FASST has more features, some unique, than do most Intermediate systems. Some of the features, triple rates for example, are usually found only on Advanced or Luxury RC systems.

In addition to its Advanced system features, the 7C FASST works in the bullet-proof 2.4 GHz frequency range. You know, it just doesn’t get any better than this in this price range. Add digital servos ($330 total) for precise performance and a very tight pilot feel and the 7C FASST resides firmly in the Great Bargain range. The 7C FASST System is so extremely easy to program that even the newest RC pilot will be able to use it to its full potential.

Get more information about the 7C FASST RC System at http://2.4gigahertz.com/systems/futk7000.html

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