The ParSer Turbine Starting Engine is an optional feature with most of our GCPs, but it is also available as a standalone ParSer Module. The PN 5-11-0010, which provides for updating existing aircraft to ParSer Starting with minimum modifications.
Click the following Youtube Video link for a video demonstrating the superior abilities of our system on a Silver Eagle 210. Pilots with some turbine time will understand the terminology and timing significance
There are essentially three different types of starts for your engine.
ParSer Start the start is initiated with both batteries in parallel, just like a normal start. At a specified point during the start, the batteries are switched into a series. This results in faster acceleration from light off to GND idle and lower peak temperature.
Soft Start the start is initiated with one battery feeding the starter while the other battery supports the primary bus. Just like the ParSer Starter, at some point, the batteries are switched into a series.
Three Step Start the same as a soft start, with an added second stage inserted briefly in between with the batteries operating in parallel before switching to a series. This gives a little boost without causing undue voltage sag.
The resulting increased voltage during the later phase of the start appears only at the starter and nowhere else in the electrical system. The inrush current and impact torque on the accessory gears is significantly reduced (softer), the acceleration of the engine is greater (faster) and consequently the peak gas temperature during start is reduced (cooler).
Our experience with this system on numerous aircraft with several make and model of engines (PT6, TPE331-10, -12 & -14, Allison 250, Williams FJ33 & FJ34, Honeywell HTS900 and Walter) has taught us that to whatever extent starting requirements dictate the weight of the batteries and the current rating of the StarterGenerator we can reduce both significantly. The reduced weight in batteries and SG rating also results in lower total hardware costs. We have test data taken in the lab on aircraft and in engine manufacturers test cells that lead us to the following conclusions:
The smallest 24V aircraft batteries available, when used in our system, will outperform two of the largest available batteries in a conventional system. To put this in perspective, compare 50lbs to 200lbs. Actual lab results, in one instance, showed our engine test cell of a 56lb battery pack feeding a 200 am SG outperformed a 500lb battery cart feeding 300 amp SG.
We have observed as much as a 50% reduction in start time and as much as 180 degree Celsius reduction in peak gas temp. It should be pointed out that thermal stress is a function of both peak temp and time of exposure and is in fact related to the area under the curve, therefore reducing both yields a second order reduction in thermal stress.
High inrush current (and therefore high torque and acceleration) from zero RPM to light off has nothing to do with the quality of the start. In fact it tends to be self-defeating because it causes excess heat in the starter and gassing in the battery, both of which detract from performance later in the start.
Extra torque from the starter after light off has a great deal to do with the quality of the start. A bigger battery and SG and heavier cables can only provide marginal improvement in this critical area because what is needed is more voltage to overcome the increasing counter EMF vs. RPM of the SG.
Using smaller, lighter weight cables between the battery and the starter absolutely kills performance in a conventional system but significant reductions in wire ga are possible with our system. The reason is obvious; the critical part of the start is after light off where the extra voltage from our system largely offsets the extra resistance of the cable. But the inrush current is less, therefore a softer start. In one test in an engine test cell we introduced an extra 40 feet of 2 ga wire and still got acceptable starts.
We have observed as much as a 50% reduction in start time and as much as 180 degrees Celsius reduction in peak gas temp. It should be pointed out that thermal stress is a function of both peak temp and time of exposure and is in fact related to the area under the curve, therefore reducing both yields a second order reduction in thermal stress.