Spark/Ignition Analysers, Round Engines?
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Spark/Ignition Analysers, Round Engines?
I seem to recall some of the older farts I used to work with at BAF maundering on abour their old Carvairs (aka DC6s) and the extraordinarily complex engine management that was required in those days. One of the features was apparently (or am I dreaming?) a panel that analysed the ignition systems of the four engines so as to troubleshoot them if required.
Any of my former highly esteemed colleagues out there or any other radial operators who recall this, or indeed any of the fine detail of engine handling of these evidently somewhat delicate systems?
And can add explanations in as much detail as you wish?
Do I recall tales of power, flap, gear and and prop settings used far out on the approach so as to avoid any changes in throttle settings at all until landing as throttle/power setting changes upset the engines? Or was I being fed a tale?
Explaations on technique would be fascinating.
Any of my former highly esteemed colleagues out there or any other radial operators who recall this, or indeed any of the fine detail of engine handling of these evidently somewhat delicate systems?
And can add explanations in as much detail as you wish?
Do I recall tales of power, flap, gear and and prop settings used far out on the approach so as to avoid any changes in throttle settings at all until landing as throttle/power setting changes upset the engines? Or was I being fed a tale?
Explaations on technique would be fascinating.
All very true Mel; I think the analyser was an oscilloscope which could be cycled through each engine in turn and then each plug on each magneto.Depending what the `picture` showed ,the `gingerbeer` could determine what condition the ignition/mixture strength was..An `ECG` for the engines in simple terms..
With respect to the selection /reduction of `power` on big radials ,for descent,the throttle(s) should not usually be reduced to the extent that manifold pressure is low enough that the propeller is being `driven by the airspeed` and prop RPM in the governing range...ie approx 15"MAP ,and 1500 RPM..A further reduction in MAP will cause the prop to be `unloaded` by airspeed an this can cause `big-end problems` with oil flow to the bearings....as the oil ways are designed to cater for the` Prop pulling the aircraft`,and not driven...
Same was true on the C-130, if one was aggressive pulling the throttles back in a descent ,one could get a Negative `Torque` indication ,but it would trigger the NTS to `coarsen ` the props...
All good reasons to set the aircraft up nicely stabilised,so you only need to keep reducing power down to touchdown.....
With respect to the selection /reduction of `power` on big radials ,for descent,the throttle(s) should not usually be reduced to the extent that manifold pressure is low enough that the propeller is being `driven by the airspeed` and prop RPM in the governing range...ie approx 15"MAP ,and 1500 RPM..A further reduction in MAP will cause the prop to be `unloaded` by airspeed an this can cause `big-end problems` with oil flow to the bearings....as the oil ways are designed to cater for the` Prop pulling the aircraft`,and not driven...
Same was true on the C-130, if one was aggressive pulling the throttles back in a descent ,one could get a Negative `Torque` indication ,but it would trigger the NTS to `coarsen ` the props...
All good reasons to set the aircraft up nicely stabilised,so you only need to keep reducing power down to touchdown.....
