by Bruce Tharpe
TURBINES
The ideal turbine for your airframe will depend on your jet experience and style of flying. The
"official" recommendation from PST is 14 to 20 lbs. of thrust, but they do allow for up to 36 lbs.
of thrust for advanced pilots. If the Reaction ARF is going to be your first turbine model, you
should probably stick to the official range. To me, the PST J800R (18 lb) is a perfect match for
the airframe. Others in this class are the JetCat P70 (17+ lb) and the Wren Super Sport (18 lb). Do not get
the impression that the Reaction will putter around like a high-wing trainer with this kind of
power! With 14 - 20 pounds of thrust, it will fly in the 120 to 150 mph range and be able to do all
types of jet aerobatics.
The next level of turbines are at the upper recommended limit, or just over it. This middle range of turbines
includes JetCat P80 (21 lb) and the Artes JF-100 Falcon (22 lb). This extra bit of power will be nice if
you plan to install a smoke system.
The most power-hungry pilots will be looking at the top end of the spectrum. The prototypes were tested
extensively at the factory with a PST J1300R (28 lbs) for power. The experienced pilots there
loved the combination, reporting not much extra speed, but lots of extra vertical performance.
They even installed one of their new J1600R (35 lb) turbines, and did demo flights at Top Gun 2008.
That kind of power gives you unlimited vertical performance, but it uses a lot of fuel and pushes the
airframe to the limit. Other engines in this class are the JetCat P120SE (28 lb), the Wren XL200 (33 lb),
the Artes JF-120 Eagle (30 lb), and the JetCat Titan (34 lb).
Kraivuth at PST wrote this to me:
"We tested the Reaction ARF with J1600R and wowwwww. I put her into vertical climb right after takeoff and she
will go out of sight if don't power down. Structure strength is more than enough to take this 36 lbs thrust.
We put her into many high G maneuvers with ease. Personally, I still think that the J800R is the best
combination. J1300R and J1600R are for show and hot rod flying".
Keep in mind that you can "detune" your turbine to put out less thrust by simply programming the ECU to
a lower rpm figure. This would be a good idea for early flights while you get used to the airplane.
RADIO AND SERVOS
You will need at least a seven-channel radio for the Reaction ARF. If you install the optional speed
brake or add a smoke system then you will need more channels. If you have extra channels, you can use
separate channels for each aileron and/or separate channels for the rudder and steering servos. Personally,
I have settled on the Futaba 9C transmitter because it is easy to program, has lots of mixing functions,
and has slider switches for flaps, which I consider much easier to use than knobs.
Digital servos are recommended for the ailerons, elevator, and rudder. I also like digitals on the flaps,
but PST recommends analog servos to prevent over current draw and possible burnout. We both prefer analog
servos for nose wheel steering and for activating air valves (retracts and brakes). The minimum recommended
torque value for each function is listed here:
Elevator (1 Servo) 9 kg-cm/125 oz-in
Ailerons (2 Servos) 6 kg-cm/83 oz-in
Rudder (1 Servo) 6 kg-cm/83 oz-in
Flaps (2 Servos) 6 kg-cm/83 oz-in
Steering (1 Servo) 6 kg-cm/83 oz-in
Pneumatic Brake Valve (1 Servo) 3 kg-cm/42 oz-in
Pneumatic Retract Valve (1 Servo) 3 kg-cm/42 oz-in
Optional Speed Brake (1 Servo) 6 kg-cm/83 oz-in
I've made a list of common servos, broken down by manufacturer, that are suitable for the Reaction ARF.
These are not the only servos that can be used, but it's a good place to start.
Download
REACTION ARF SERVO LIST 21.2KB .pdf file
RETRACTS, WHEELS, AND BRAKES
PST manufactures their own brand of retracts, wheels, and brakes, and offers them in a complete
package that is perfectly suited to the Reaction ARF. However, the generic mounting areas for the
retract units make it relatively easy to install other brands of equipment. PST specifies
Robart Heavy-Duty 630 Series or Spring Air 700 Series as possible alternatives. Some strut length
modifications may be necessary to make them fit properly.
OPTIONAL FUEL TANKS AND HEADER TANKS
The ARF package includes an 84 oz. (2.5 liter) fuel tank, which is plenty for the smaller turbines. They
also offer an optional one-liter fuel cell that can either be used to extend the fuel load (for
the larger turbines) or as a tank for smoke fluid. Although not included in the ARF package, I highly
recommend the installation of a header tank designed to eliminate bubbles in the fuel as it travels to
the turbine. Perhaps the best known header tank is the UAT from Bob Violet Models. PST also makes their
own , called the Bubble Sucker, based on a baby bottle. Links to header tank options are given below:
- LINK:
BVM Ultimate Air Trap (UAT)
- LINK:
Hanson Super Trap
NEW! Optional Main Fuel Tank. PST now offers an optional 3.8 Liter fuel
tank (equals 1.0 gallon!). This is meant to replace the standard main tank and optional 1L fuel cell. If you
are going to use a larger turbine (25 lbs. thrust or more), you may want this extra fuel capacity. If you want
to install a smoke system, you may want to stick with the standard main tank for fuel and 1L fuel cell for
smoke fluid. If you order this new 3.8L tank for $60, it will replace the standard tank in the ARF package -
you will not receive the standard tank.
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