Company History:
Rand
Rand Actuators
By Jay Mendoza
December, 2009
Rand Take Off Products developed a line of actuators for galloping ghost, Herb Abrams being instrumental in this endeavor. Over the course of about 5 years from 1965 to 1970 1 to 3 function pulse systems were a very popular low-cost alternative to more expensive full house digital proportional systems. The low rate 3 function LR-3 offered proportional Rudder, Elevator, and 5 position Throttle control (REM). The HR-1 was a high, or low rate single function actuator from rudder only or elevator in a dual actuator high rate system. The HR-2 was its mate and was for rudder and throttle control in low rate or dual actuator high rate systems. Over the course of time Rand offered many versions, each of which were either improvements, or variations for different applications. Eventually Rand sold the LR-3 with a battery, an integral electronic switcher circuit, and wiring harness as a complete combo they called the GG- Pack which was for REM low rate systems. They also offered another combo called the Dual-Pack which was an HR-1, and HR-2, and battery pack, both actuators had integral switchers complete with rate decoder circuitry for independent elevator control.
The LR, and HR series of Rand actuators were quite popular as they were small, light, and setup for use with pushrod type control linkages which greatly simplified the installation and adjustment of the plane. The LR-3 offered motor control, which many others did not, as such it was produced in the greatest numbers and versions. Eventually Rand became the dominant pulse proportional actuator as almost every pulse propo manufacturer offered them with their systems. Due to that, there is quite a bit of variation as some versions were OEM and not sold individually but instead were made custom for the manufacturer of the radio system they were intended to go with. Typical examples of non-standard OEM Rand actuators are those supplied with Hallco, and Min-X systems.
Pulse rates used for low rate(LR) were from 3 PPS to 16PPS with 6PPS at neutral. The high rate(HR) actuators could be run up to 20PPS at neutral (pulses per second). Although higher rates could be used, the actuator motor draw becomes excessive and the motors begin to get quite hot as a result. The dual high rate actuator systems give independent interaction free control response of elevator and rudder, and no elevator kick up during throttle changes. The low rate LR-3 had a tendency to give progressively more up the harder you turned, and also gave full up on throttle changes, this was the trade off for a simpler mechanical decoding system in an all-in-one actuator/servo. Linkages with negative exponential for up elevator could be rigged by offsetting the angle of the control horn on the elevator, and throttle changes were made in a series of blips rather than all at once to reduce the nose up tendencies of the LR-3, plus pilots also flew with a bit of down trim, or pushed forward on the stick a little.
Another drawback was that the earlier Galloping Ghost transmitters had too much throw of about 20-80% to 80-20% and this caused the LR-3 to move too much and go around, cycling the throttle whenever full rudder or up elevator was applied. To combat this, a sheet of plywood with a cutout to limit the control stick’s movement was often affixed to the face of the transmitter. Later GG transmitters were set-up for a 30-70% to 70-30% pulse shift, which was perfect for the Rand actuators. Even so, many later versions of transmitters had elevator and rudder throw adjustment pots added to fine tune the Rand for no cycling/go-around. This was due to the fact that there was some slight variation in the actuators such as the motors and springs, friction of the gears, and battery voltages being used. It is interesting to note that the Controlaire Ghost actuator overcame many of theses problems but was never as popular.
Initially, the Rand came out in 1965 when most receivers used a SPDT relay to switch battery power to the actuator. The popular method was to use one battery pack for the receiver, and a second larger more power pack to drive the actuator. If a single battery pack was used, the resultant noise from the motor and relay caused enough noise to reduce the effective range considerably. Typically a 4 cell NiCad battery, 4.8 volt pack center tapped at 2.4 volts was used to create plus and minus 2.4 volts for running the actuator motor in both directions. To reduce the weight, and noise caused by switching high current through a relay, Rand came up with a transistorized switcher for the later Pack versions of their actuators. This eliminated the second battery pack and heavy relay, which was prone to trouble under vibration and G-forces as encountered in model planes, and improved reliability considerably at the small cost of slightly increased current consumption.
Rand Pack wiring colors were as follows: Yellow for plus 3.6 volts, Green for minus 3.6 volts, and Blue for signal. Other wiring colors such as red and black for plus and minus and a third color such as white for signal was also used in the kit form of the decoder and switcher. Rand, and later Ace offered theses as separate items for those wanting to upgrade earlier versions of Rand actuators to a GG, or Dual Pack. A 2.4 volt version could be made to work at 3.6 volts by adding a resistor in line with one leg of the motor to drop 1.2 volts. The 2.4 volt versions also used a slightly lighter tension spring as compared with the 3.6 volt versions. The HR1 and HR2 that came in the Dual Pack also had lighter springs for high rate operation.
Ace R/C took over sales of the Rand products and the later versions sold by them lacked any sort of logo or name on the packaging. As Ace sold out the remaining stock, there was some interchanging of older and newer parts, resulting in some odd combinations that are therefore difficult to identify as a particular vintage or version. One must look at them and note the newest piece, as that is a guide as to when it was assembled. One must also be aware that Rand sold many variants to OEM companies like Hallco, so there are some models of Rand actuators that are difficult to date due to them being different from the models sold individually at a retail level. Bear in mind too that hobbyists would also swap parts making odd combinations that were never released by the factory.
MAINTENANCE
Typically, all the Rand actuators you encounter today will have issues with the throttle quadrant gear being cracked at the hole where the throttle arm bushing passes through, making it a loose fit and therefore the arm will not stay in adjustment. Since new parts are not available, repairs are the most practical solution. If you have access to a machine shop a replacement can be made from brass or plastic, albeit time consuming to do so. The return arms on this gear which act as ratchets when the throttle is at either extreme of it’s travel often break, a small piece of music wire can be used to pin them back together. Missing springs can be sometimes gleaned from old control stick gimbals or cassette tape decks and VCRs. The “E” clips which always are missing can be purchased at any hobby shop that carries R/C car parts. Most actuators will need a complete tear down, cleaning and lube, silicon oil and grease are the only safe lubricants to use on plastics. The motor will benefit from a cleaning with a spray motor cleaner as used for model cars, but you must test them to be sure they do not harm the internal plastics of the armature, and you must remove the motor from the actuator to prevent getting the spray on the actuator’s plastic parts. Be sure to put a very small drop of oil on the motor shafts oilite bushings before re-assembly. As with any vintage R/C component of this age, it pays to remove all wiring, re-strip the ends, tin them and re-solder them to eliminate any possibility of them failing in flight due to broken strands and fatigue. Under test a good actuator will pull less than 350 mill amperes with no load, if it exceeds that then something is binding and need to be corrected. Rusty/corroded shafts, chipped/broken/missing gear teeth, a seized motor, too stiff of a spring, or dried on dirt and oil residues are the most common causes. Often the base will be twisted due to the way it was mounted. Placing the base in a hot water bath will usually soften it just enough to make it return to it’s original shape, look for the shafts to all be parallel.
