About Tim's Universal Timer

Things that have been done with the TUT

The TUT is so very versatile that it is difficult to describe what can be done. So instead, I'll describe what has been done with the TUT. Each of these programs is written in a scripting language that is unique to the TUT, and is designed to make it easy to write such programs -- so if you see that the TUT does almost what you want but not quite, please contact Atomic Zombie Workshop with questions about what the TUT can do.

Howard Rush's FAI Program

The driving force behind the TUT development program was Howard Rush's desire to tweak the behavior of his airplane beyond what was available from an Igor Burger accelerometer-based timer. Howard still wanted to use an Igor Burger timer to control his motor during the main part of the pattern, but he wanted different behavior during the starting and ending phases of the flight.

This was accomplished by with the TUT by writing a custom program. The Igor Burger timer is plugged into one of the TUT ports, and the airplane's ESC is plugged into another. (The other two ports are used for annunciator lights to alert the pilot to the active flight phase).

With Howard's FAI program running, the flight is divided into six phases. Most of the times and throttle settings can be changed using the JetiBox or USB port.

Howard's FAI program uses all four I/O ports in the TUT: one is used for input from the Igor Burger timer, one is used for output to the ESC (electronic speed control), one is used to indicate whether the TUT is taking input from the Igor Burger timer or is using its own internally-generated throttle command, and one is used to indicate the end of the flight, in a manner that helps the pilot locate the motor cutoff in a desirable spot relative to the wind.

This program can use the gyroscope on the TUT-HR to determine the cutoff point of the approach lap. However, the way that Howard Rush set his program up for the 2014 World Championships, the gyro was not used. So one could run this program on a TUT-FC and get the same functionality as Howard did at the World Championships -- but using the gyro is more fun.

In the idle phase, the motor throttle is held at 0%, so the motor stays off while the pilot walks to the center of the circle. This phase lasts for 20 seconds, and is followed by the takeoff phase.
In the takeoff phase, the motor throttle is held at 60% for 10 seconds to give a smooth takeoff instead of the sudden burst of acceleration typical of electrics. The takeoff phase is followed by the pattern phase.
In the pattern phase, motor throttle control is handed over to the Igor Burger timer, if it is present. This hand-over of control happens over a period of 1.5 seconds, to prevent sudden surges in the airplane speed during judged level flight. The pattern phase lasts for 280 seconds and is followed by the post-pattern phase.
(If there is no input from a timer, the TUT defaults to a throttle setting of 75%. This not only saves your flight (and plane) in the event of a loose connection or a malfunction of the Igor Burger timer, it also means that you can run the TUT without the Igor Burger timer.)
In the "post-pattern" phase an annunciator LED (available from Howard) blinks once every 5.2 seconds, and ends bang on a blink. This phase lasts for 20 seconds and is followed by the approach phase. The pilot can shorten or lengthen his laps as necessary, by flying high or performing loops, to cause the airplane to enter the approach phase at the desired point.
(Howard used this feature because he wanted to control the position of the motor cut-off in the pattern, but he wanted to avoid any hint of using an engine cut-off device that was under pilot control, based on some ambiguous wording in the 2014 FAI rules.)
In the approach phase the throttle ramps up to 90%, and stays at that setting for one lap or a timeout, whichever comes first (Howard had his TUT set up to use the timeout). The approach phase is followed by the landing phase.
The landing phase simply cuts the throttle to 0% and keeps it there, ending the flight.

Howard Rush's AMA Program

One of the salient features of Howard's FAI program was that the TUT did not provide any shutoff mechanism. This was done because Howard felt that there was an ambiguity in the rules, and he neither wanted to make any waves about the wording before the contest, nor did he want to be challenged on the rule at the contest.

This was not an issue for AMA competition. For AMA competition, Howard wanted to be able to use the TUT to detect a shutoff loop late in the pattern, and enter an approach sequence after a shutoff loop is executed.

The same four I/O ports are used in Howard's AMA program, except that instead of blinking, the "end of flight" annunciator channel is used to tell the pilot that the TUT is armed and ready to detect a cutoff loop.

The initial flight phases are identical: they only differ in the final phases:

Idle, Takeoff, and Pattern phase are all identical to the FAI program.
After the pattern phase, the timer enters a "post-pattern" phase. An annunciator LED (available from Howard) comes on to warn the pilot. When the pilot executes a loop lasting more than 3/4 of a turn, the TUT waits until the end of the loop, then enters the approach phase.
The approach and landing phases are identical to the FAI program.

Tim Wescott's Test Program

An amusing aspect of the TUT development is that while its primary use is as a timer for electric flight, its developer, Tim Wescott, flies with glow engines. There are a number of initiatives active at the Atomic Zombie Workshop to use the abilities of the TUT to fly better with internal combustion, but Tim has yet to use it in competition.

In order to test the TUT, and Howard's competition programs with a glow-powered setup, and to have a platform for gathering data with it, Tim has his own program which is customized for use with an internal combustion engine.

Like Howard's TUT programs, Tim's uses all four of the available I/O channels. One channel is configured to take input from an Igor Burger timer (although this has never been tried). One channel is connected to a switch, and is used to set the engine needle valve before launch. One channel is used to drive a throttle servo. The final channel is configured to blink an annunciator LED in a similar manner to Howard's FAI program (although it has not been used).

The phases of Tim's test program are as follows:

The pre-idle phase is reached any time the engine set-up switch is closed. It sets the engine throttle output to the pattern setting. In a normal flight, this is used by the pilot to set the engine needle valve, exactly as one would do for a normal stunt plane. As soon as the switch is opened the TUT goes to the idle phase.
The idle phase holds the throttle at 12% (in practice, 25% is usually used, to prevent the engine from stalling). Idle phase lasts for 20 seconds while the pilot saunters to the center of the circle. Idle phase is followed by the takeoff phase.
The takeoff phase holds the throttle at 60% (65% or 70% in practice), and lasts for 10 seconds. It is followed by the pattern "A" phase.
The pattern "A" phase holds the throttle at 75% throttle, and lasts for 200 seconds, which should carry the pilot well past the outside round loops. The outside round loops, are the last point in the pattern when the airplane does more than 1.5 consecutive loops (after the vertical eight, there are no round loops of more than 360 degrees rotation). The pattern "A" phase is followed by the pattern "B" phase.
The pattern "B" phase is identical to the pattern "A" phase, except that it is terminated either by the TUT after 100 seconds, or by the pilot executing more than 1 3/4 consecutive loops. This allows the pilot to precisely determine the beginning of the approach phase. The pattern "B" phase is followed by the approach phase.
The approach phase is like Howard Rush's approach phase, except that when Tim sets it up, it terminates one full lap, cutting the airplane off at the point where it exited the cutoff loop. The approach phase is followed by the landing phase
The landing phase cuts the throttle to 0% which, on a correctly set-up engine, cuts off the engine and allows the airplane to land.

Fred Cronenwett's Engine Sequencing Program

Fred Cronenwett's engine sequencing program really shows the versatility of the TUT's programming model, because the staff at Atomic Zombie Workshop had no inkling that anyone would want such a thing, yet it turned out to be a fairly simple program to write.

Fred's engine sequencing program is designed to give a realistic engine startup sequence to a multi-motor, electric powered model airplane. With this program, the first motor and the TUT are both connected to the receiver with a Y harness. The other motors (up to three) are connected to the other three TUT channels.

When the throttle is advanced above 5%, the motors start up in sequence, with five seconds between motor starts. When the throttle is cut, the motors shut off in sequence.

Traveling through the phases of Fred's program is more confusing, because the program will go through them in both directions, depending on the throttle setting. Also, if the throttle is suddenly advanced, the program will jump to the final phase.

Off phase is where the program starts. All throttle outputs are held at 0%. The TUT stays in the off phase until either the throttle is advanced past 15%, in which case it jumps to the fly phase, or until the throttle has been advanced past 5% (idle), in which case it jumps to phase 0.
In phase 0 all throttle outputs are held at 0%. The TUT stays in this phase for five seconds, at which point it either goes back to off phase if the throttle is below 5%, or to phase 1 if the throttle is above 5%.
If at any point the throttle is advanced past 15%, the TUT will jump to the fly phase, to avoid a serious asymmetrical throttle condition.
In phase 1, channel 2 output is held at 5% (idle) while channels 3 and 4 are held at 0%. The TUT stays in this phase for five seconds, at which point it either goes back to phase 0 if the throttle is below 5%, or to phase 2 if the throttle is above 5%
If at any point the throttle is advanced past 15%, the TUT will jump to the fly phase, to avoid a serious asymmetrical throttle condition.
In phase 2, channel 2 and 3 outputs are held at 5% (idle) while channel 4 is held at 0%. The TUT stays in this phase for five seconds, at which point it either goes back to phase 1 if the throttle is below 5%, or to phase 3 if the throttle is above 5%
If at any point the throttle is advanced past 15%, the TUT will jump to the fly phase, to avoid a serious asymmetrical throttle condition.
In phase 3, all output channels are held at 5% (idle). The TUT stays in this phase for five seconds, at which point it either goes back to phase 2 if the throttle is below 5%, or to the fly phase if the throttle is above 5%
If at any point the throttle is advanced past 15%, the TUT will jump to the fly phase, to avoid a serious asymmetrical throttle condition.
In the fly phase, all three output channels echo the throttle input on the input channel. All four motors should respond to throttle together. The TUT stays in this phase until the throttle drops below 5% (idle), at which point the TUT will jump back to phase 3 to start the engine shut-off sequence.