Air Craft DataSheet

SEE JETI "ADVANCE" TIMING/BRAKE INSTRUCTIONS

Air Craft offers a wide range of Jeti and Hacker Master brushless speed controllers for airplanes, helicopters, R/C cars and trucks. Jeti and Hacker ESC are outwardly similar; both are assembled at the Jeti factory and share the same dimensions and weight for those controller sizes which are offered in both brands.  Hacker ESC differ from Jeti in that the Hacker-designed software affords greater control over timing and frequency settings. Also, several sizes and types are only available under the Hacker banner. The variety of features can be confusing, so we've tried to lay it all out for you here.

It's important to understand that different motor types have different timing and frequency settings at which they reach peak efficiency.  Ideally, you want to choose a motor controller which has timing/frequency fairly well matched to the motor you intend to run, and you don't want to pay any more than necessary for the optimum (or near optimum) setup. In general, frequency has much less impact on efficiency than does timing, and if you have a choice between "too much" timing advance, or "too little", it's better to go with the lower setting. The information on optimum modes below can also be affected by motor Kv, magnet/rotor type, peak rpm, and other considerations.  Depending on the motor, it may not matter much that the "optimum" timing is achieved.  Mega motors, for example, run very well on any timing setting from modes 1 to 3.

These are the timing and frequency settings that may, or may not, be selectable:
  Timing
    Mode 1  Optimum for Hacker, Lehner, and other 2-pole motors
    Mode 2  Optimum for Aveox and AstroFlight motors
    Mode 3  Optimum for Mega, Jeti, Plettenberg and other 6-pole motors
    Mode 4  Optimum for AXI, Kohler, Actro and other Outrunner motors

  Frequency
    Mode 1  Optimum for Hacker, Lehner, and other 2-pole motors - 8 kHz
    Mode 2  Optimum for Aveox, AstroFlight, Mega, Jeti, Plettenberg - 16 kHz
    Mode 3  Optimum for AXI, Kohler, Actro and other Outrunner motors - 32kHz

Some Additional Model Information...

• JETI ADVANCE SOFT PCO
  In the Jeti-Hacker lineup, this new feature is found only in the Jeti ADVANCE controllers.  These controllers, like all Jeti/Hacker models, will signal when the motor pack is near 0.7v/cell. When that occurs and the brake is set to OFF, the ESC will GRADUALLY reduce power to the motor to signal that it is time to land, which allows better control of the aircraft than a complete power cut does, especially for models with high wing loading.  When the brake is set to ON (for gliders with folding props), the motor cut is hard, to reserve maximum battery capacity for extended gliding and long landing approaches.  In this case, as with previous Jeti ESC, limited motor power can be restored by throttling back to zero, and then forward again to adjust the landing approach, or go around one more time.
   
• HACKER MASTER HELI CONTROLLERS  (see mode setting instructions here)
  These new HELI controllers are bringing affordability to electric heli pilots everywhere, and are getting excellent reviews for smoothness, reliability, and ease of use.  Instead of setting brake ON/OFF, the Heli ESC allow you to chose between "Normal" and "Constant RPM" (governor) modes.  By adjusting your throttle to less than +/- 100% in this mode, you leave a margin which the controller automatically uses to maintain rpm as you maneuver - that makes flying easier, and aerobatics much smoother. Given that Helicopters may use four or more servos, and one or more gyros, Air Craft strongly recommends that HELI BEC operation be limited to 9 cells or fewer. (see "BEC vs OPTO" below)
   

SPECIFICATIONS for all HACKER and JETI BRUSHLESS ESC

CONNECTORS for BATTERY to ESC

About 90% of speed controllers returned for problems encountered in flight (motor cuts under power, etc...) turn out to be fine.  In most cases the problem can be traced to one of three things: 1) battery condition poor, 2) battery type inappropriate for amperage level, 3) connectors too small, poor quality, or worn out.  When you choose your motor, ESC, battery, and propeller it's very important to match everything to the amperage you will draw, especially battery and connectors.

BATTERY > ESC Connectors for Current Draw:
1A to 6A - JST connectors or Dean's Micro (for Micro, Indoor, Slowflyers)
4A-11A - Dean's Micro or 2mm Gold connectors (S280-350)
4A-20A  - 2mm Gold connectors or MPX (S400-S480)
18A-75A - 2.5mm silicone wire and 4mm Gold connectors (Most 500/600 class and brushless motors)
50A-120A- Robbe 4mm Hi-Amp Gold connectors and 4mm silicone wire (Competition gliders, Pylon, etc...)

And about 95% of the ESC which come back blackened and burnt are the result of connecting the battery to the ESC backwards, so be absolutely sure that you have plus and minus matched up before you connect the battery.  It's easy to make a mistake, so polarized connectors, like all listed above, are a very good idea.

If you have questions about the appropriate current draw for a particular battery, just email us.

Some General Information about Speed Controllers, Brushless Motors, and Batteries

CONNECTING ESC and MOTOR

Brushless motors use 3-phase alternating current supplied by the speed controller, so there is no "plus" or "minus" as in brushed motors.  This means that you can connect any of the three wires from the ESC to the three at the motor without worry.  Do this with the propeller removed and advance the throttle until the motor is turning smoothly, then check motor shaft rotation.  For direct drive, planetary gearboxes, belt drives, and inner-driven gearboxes the motor shaft should turn counter-clockwise when viewed from the front (normal rotation).  For off-set gearboxes (the kind where the small pinion gear runs on the outside of the large spur gear)  the rotation should be clockwise viewed from the front.  If direction of rotation is not what you need, simply choose any two wires and reverse them - simple!  If your wires have colors, normal rotation will be something like: red>red, yellow>white, black>blue/black, but it's not important as long as you have the proper motor rotation.  For smaller motors you can solder the ESC wires directly to the motor wires, or use some of the new MP Jet 1.8mm or MP Jet 2.5mm connectors.  For more than 35 amps,  the 3.5mm Gold connectors are best - use the excellent Polyolefin 4.8mm shrink tubing to insulate them.

LITHIUM POLYMER AUTO-CUT SETTINGS

Lithium Polymer batteries can be damaged if discharged below 2.7 volts.  Therefore it is important to know the auto-cut capabilities of the speed controller you are using.  Auto cut is the feature built into the ESC which monitors battery voltage and stops the motor when the battery voltage falls to a certain level.  That level is the "Auto-cut voltage".

The most programmable speed controllers with respect to auto-cut are the Castle Creations line, with settings for 1-4 cells lithium polymer.  The new Jeti Advance have an auto-detect circuit for Li-Poly packs, and set auto-cut appropriately in that way.  JES-04-3P ADV has 2-3 cell auto detect. JES-08-3P ADV and higher detect 2-4 cells, but should only run 3 cells max on BEC.  The Hacker Master ESC from 4A to 30A models are selectable for 2 or 3 cells Lithium Polymer.

Jeti Gold do not have auto-cut settings.  Because their minimum voltage is 5.0V, they can safely be used with 2-cell lithium polymer packs (2.5V per cell is OK as the battery will come back 2.7V+ under no load).  If you are using 3 cells lithium with the Jeti Gold ESC, however, you need to be very careful to leave some reserve capacity in the pack and land before auto-cut level is reached.

BEC VS OPTO

The BEC allows you to power the Rx and servos from the motor pack, thus eliminating the weight and maintenance of a separate Rx battery pack. That's it for BEC advantages...

The BEC converts the motor pack voltage (say 9.6V) to what the Rx requires (usually 5V). The difference of these two numbers (in this example, 4.6V) times the amperage draw of the servos equals the watts that the BEC will convert to waste heat. If the waste heat rises too high, the BEC will fail, causing a "no control" situation. Increasing the cell count (bigger difference in voltage) or number of servos (higher amperage draw) increases the chance that the BEC will be overstressed. The BEC can also be affected by heat created in the ESC as it passes current to the motor, so running at high amperage, or for extended periods at 60-90% throttle, can contribute to BEC related failures, too. BEC systems can also allow noise generated in the motor to pass down the cable to the Rx, causing glitches and, in severe cases, another "no control" panic scene. Although modern ESC have improved on this point, you still need to be concerned about the power remaining after the ESC has cut motor power due to low battery voltage - with nine to ten cells you may have little time to safely land before all power is lost.

The "OPTO" ESC require that a separate battery pack be installed to power the receiver. That's it for OPTO disadvantages....

Because the motor control circuitry is optically isolated from the line to the Rx, glitches due to motor noise are greatly reduced. Since you have a separate battery pack for the Rx, you can use the motor pack until it cuts off at low voltage without worry. This might allow you to use a smaller, substantially lighter motor pack, because you never feel like you have to leave a "reserve" for the BEC. You can run your motor at 80 amps if you like, and not worry about losing control of the servos (assuming the ESC can handle 80A, that is). You can fly your glider for an hour if you find good air, without worrying about the BEC. You can reduce the chance that your airplane will be destroyed, or that someone will be hurt on the ground.

But BECs are really good to have, sometimes. A small Rx pack (300 NiMH or 270 NiCd) weighs 28-38g. In a Speed-400-sized plane or smaller, that's a big percentage of the total flying weight, so the advantage of BEC is great.  BECs make good sense in small planes, and they are generally very reliable on eight or nine cells, up to 35A, even in larger models. In a model with just a few lightly-loaded servos, safely going beyond those numbers may be possible.

On the whole, though, BECs are overused in larger models.  Consider that, in a four-pound (1.8Kg) airplane, a 28-40g Rx battery is insignificant, really - just a few percent of the all-up weight that won't materially change the way the plane flies or feels - It's just another battery to charge. Considering all the advantages of OPTO, especially the safety aspects, charging an extra battery is a pretty cheap ticket...  Or consider our S-BEC (Super BEC), which is a switching-mode power supply to replace Rx battery packs.  It can safely be used for packs from 7 cells up to 30+.
 

DISABLING BEC to USE MORE CELLS (for Jeti & Hacker ESC)

Lets say that you have a 5 pound Skywalker that really needs twelve cells to fly decently.  Your Jeti 40A ESC says 6-12 cells, but you KNOW that 4 servos, 12-cells, and a five-pound airplane is a recipe for danger.  So how do you disable that BEC to use 12 cells?

Well, it's easy... all you have to do is attach a separate receiver battery pack and switch harness. Plug it in to any open slot in the receiver. Use that to turn the ESC on and off, and leave the original BEC switch in the "OFF" position. To be extra safe, remove the red wire from the connector block that goes into the receiver throttle channel (just push the little retainer clip down with a piece of wire and slide the wire out, then tape it up).

By the way, the cell counts listed on the Jeti/Hacker ESC are the real limits. For example, the JES-40-3PBEC is rated for 6-12 cells - and you can't exceed that 12-cell limit, even after the BEC is disabled. Jeti has included voltage limits in the ESC to insure that the control logic circuits get the proper voltages. If you attempt to exceed the rated voltage, the ESC simply won't arm. The Jeti / Hacker 70-3POPTO, for another example, are limited to their rated 16 cells by the same protection circuit.
 

(all the content on this page is the sole property of Air Craft and may not be distributed, copied, paraphrased, or used in any way by any other commercial entity - April 12th, 2002)