Governor Evolution Â

          I have been spending considerable time and effort evaluating various types of both rotor and engine governors. I have been involved in this process since 1995 and have experienced first hand many changes and improvements. These changes came gradually due to the more limited electronic resources available at the time and the small nature of our hobby. Manufacturers of governors came and went while others hung in with the same design. Still others marketed a common unit by simply adding their own labels. Today things are changing due to flash ROM and the common availability of SMT process to the smaller manufacturer. Larger manufacturers are often focused on many products in order to stay in business; these may include model airplanes, boats helicopters and sometimes radio equipment. Their attention and resources are divided by this very nature. During the last 18 months I have been in touch with a small company called Model Avionics. They are dedicated to radio controlled model helicopters from an electronic standpoint and are highly focused upon engine governors. The TJ designer Paul Beard, regularly flys RC helicopters. I have enjoyed many changes over the 18 month time period to an already well functioning governor. The evolution of the Throttle Jockey governor also came about by way of average model helicopter pilot input. That would be people like you and I.

          The first version took the RC helicopter community by storm due to the exceptionally good performance coupled with a very reasonable price. The popularity of 3-D flying does not hurt either, as this is a prime application for any governor. Playtime for many is at a premium and governors take much of the fine set-up work away from a hobbyist. As crude as the first TJ unit looked due to the lack of a cosmetic plastic casing did not remove its welcome by most everyone, once appraised in the air. The problem with the first unit in production is that it left out people on a tight budget in need of a cheap way to extract governor 3-D performance from their helicopter. This has to do with the cheaper radio system being fully tasked on all 6 channels when using a switched heading hold or dual rate gyro. Price conscious people in want of a cheap way out were being penalized by earlier gyro/radio purchasing decisions. A competitor’s governor product line offered such flexibility but at double the cost. Once this was realized, the next generation TJ emerged with an onboard rpm adjuster freeing up any previous radio demand.

 

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         At about the same point in time the upper operational limit was increased with the newer “Extreme TJ� version allowing engine speeds up to about 20,000 engine RPM. This was good for those few wanting to access very high rotor rpm with the smaller engines but additionally of interest to those competing in drag racing etc. For many this added extra did nothing either by way of performance or price change. Still the fact that a small change was made to satisfy a few clearly demonstrates a willingness to quickly follow smaller but substantial market demands. Two product amendments in a short time span to an already useful and successful device is a big welcome surprise.

          Today we have the latest addition to the Model Avionics governor family named the TJ Pro. It combines all previous TJ features and adds others. This unit is destined towards the flyer needing the extra edge in governor performance. I will forewarn you that for many the added performance over the existing units is small and most likely accessed by those having the flying skills and support equipment to appreciate it. It also requires a special super servo to take full advantage of its design. Unfortunately the faster super servo adds substantial cost to engine management even though the TJ Pro certainly does not. Like most cutting edge things it follows the “theory of diminishing returns� cost wise. Fortunately the SS feature is selectable in the TJ.

            If you are running average speed servos on the swashplate then the governor response time needs only be so fast. If however you are running high speed digitals and in addition utilizing this potential through your flying style along with the supported engine power, then the super servo support will give the most notable benefit. Most all governors have a lag time unrelated to servo speed and more relevant to the update rate from the governor to the servo. Sometimes the throttle response of the engine can be a limiting factor for the speed of engine torque changes. A faster servo in these governors is usually a waste of money, but not so with the Jockey Pro. For the expert, SS support is a reasonable trade off. A good analogy would be the top HH gyro products available today compared to other common HH gyros.

         Unlike the earlier amended changes to the original TJ, the Pro unit is completely new in appearance, firmware programming, and internal/external construction. Expect a polished appearance and higher grade (complexity) internal components. The product has taken on a new physical and functional standard, which complement each other. The set-up of the unit however still remains very simple to complete. As a user, one will find all the features available independently on previous TJs now all bundled up into one unit. In other words the TJ Pro may now have its rpm programmed (9500-20500) either in the unit or remotely from the radio transmitter. It retains a wide spread installation application, but now it does so in one version.

 

         The TJ pro has room in its electronic architecture to handle future improvements or additions. One item currently being worked one is a throttle mixture input to the main carburettor needle by way of an additional servo. As explained to me the theory is to initially lean the mixture during throttle punch out and then richen it when the major power is on tap for cooling purposes. The extra accessory TJ Pro port supplies rpm rate of change, target rpm along with throttle position. I’d surmise from this description that a piggy-back unit would be used between the TJ and a mixture servo. Presently there is an onboard glow add-on that accepts data from this port. It is claimed to increase engine power and throttling transition.

 

         The device is retained into what appears to be a small gyro sensor like casing. It looks identical to the CSM micro 560 gyro casing. It has two LED indicators labelled “Set and Sens�. A Manual adjuster pot (Man) is positioned next to them for on-board RPM setting. Six ports are located at the lower front and unlike the former versions it has no hard wiring into it. The unmarked recessed port is for factory programming and QA (quality assurance) testing. An integrated battery low feature electrically removes the TJ from the system  at 3.56V and below. Normal throttle signals are then fed through to the servo. Included are two male to male indexed wiring harness extensions, two magnets, a 30 and 50/60 sensor mount, one Hall sensor with a slightly longer indexed lead, and of course the dedicated instructions. A very small but appreciated add on is the “Chinese Finger Trap� wire sheathing included with two Ty-raps, mounting tape,  and a short piece of shrink tubing. Personally I prefer to use CSM gyro mounting tape on all applicable components.

         The green LED is a triple purpose indicator, one of setup mode, one of super servo support by changing the green color to yellow, and finally a status for the throttle stick engagement point. The status portion will be green or yellow dependant upon if you are in SS mode or not. The red LED as with other versions is for accurately setting the air gap between the magnet and the sensor.

         Evaluation is carried out on a Raptor 50. The first tests are in the non-super servo mode using a regular sport servo. No surprises here since it performed exactly as previous TJ versions which is pretty good. At this point I’d have to call it a performance and technical draw between it and the GV-1 with all factors averaged out. The GV-1 seemed to extract slightly more engine power abet with a looser control on rpm.

         The next test is using the TJs super servo mode with the same Raptor 50 helicopter packing a 250 hz JR  DS8417 digital throttle servo. The 8417 servo specs are .10@ 60 degrees at 80 in/oz torque. Quite impressive and quiet expensive for a throttle application, which by the way was robbed from another healthy Raptor’s tail rotor pitch control. The cyclic and collective servos in this test are much slower at about .20/sec/60degrees rotation giving the Pro a sure speed advantage. This combination is tested in both SS and normal mode to thoroughly check our results.

         During the SS test we found the performance of the Pro to notably surpass that of any other governor on the market. Over speeding is a non issue and engine power is available immediately with no lag under all conditions. This assumes of course the helicopter is not over pitched. We are unable to discern a change in rotor speed during normal and all 3-D manoeuvres completed. Typically tail slides are hardest to prevent overspeeding and usually aggressive multiple flips and rolls controlled by a governor cause a small lag in engine note. This configuration does not. It is a very accurate combination with excess potential only to be harnessed through the use of faster swashplate servos.

                     The next check came with the above combination switched into the normal or non-SS mode with all else remaining the same. Here we found a smaller difference when comparing SS mode to the average .22 speed non-SS throttle servo situation. The biggest bang for the buck comes from using a very fast servo plugged into this governor with the SS mode being the rather tasty frosting on the cake. Although we could hear a change in engine note with the fast servo/non-SS it performed as good as a GV-1 but without any overspeed whatsoever. With a slow economical servo tied to the Pro, the GV-1 installed in our aircraft has a very slight overall performance edge. I have found a faster servo to do little for increasing the GV-1 performance.

         As a final confirmation we leaned the engine in the SS mode just enough not to enter a “wah-waa� condition typical of poorly tuned Raptors. As the name suggests this noise is a condition of rapid engine oscillation with a corresponding tail wag. When we switched to the non-SS mode with the same fast servo this oscillation became known. The SS system is fast enough to override a marginally poor midrange.

Basically to acquire cutting edge TJ Pro performance you will have to pay extra for a higher end SS throttle servo. When you consider the governor options available today you will still be further ahead with the additional servo cost added to the price of the TJ Pro. Do you need to change governor brands? That depends on your flying skill, financial situation, and personal expectations along with existing equipment.