Hartzell or other C/S?

[gmcjetpilot]

Originally Posted by Bevan

Terry, Because it passed with LASAR, I wonder if that means OK for Lightspeed. Anyone know? Bevan

We're experimental and like a 1000 separate aircraft manufactures, so Hartzell can't analyze ever combo we come up with. How many pipes, ignitions and inductions are there?

Electronic ignitions are all considered about the same. Hartzell actually used Light Speed for many or most of their test. What's assumed is electronic ignitions are equivalent. Why? TWO THINGS: One they put out a huge strong spark, which makes a stronger power pulse; Two, they are dead accurate and fire with such precision they tend to aggravate harmonics. Mag timing kind of floats around a little, and of course mags a have much weaker spark.

I want to emphasize the word ASSUME. If the actual combo was not tested its a guess. The only way to know for sure is test it on your plane with all the parts. Call Hartzell and tell them what you have and they will make an educated guess of how your configuration compares to whats been tested. When you get into high compression, fancy cold plenums, fancy cams, pipes and ignition you are experimental all the way.

[Andy_RR]

Originally Posted by gmcjetpilot

One they put out a huge strong spark, which makes a stronger power pulse; Two, they are dead accurate and fire with such precision they tend to aggravate harmonics. Mag timing kind of floats around a little, and of course mags a have much weaker spark.

George, how did you come to this conclusion? This appears a little like received wisdom to me.

All the spark can do is initiate combustion. A higher energy spark will result in a lesser ignition delay, but the burn rate will be more or less identical. What electronic ignition systems do (over magnetos) is advance the ignition. It is predominantly the advanced ignition that is responsible for the 'stronger power pulse'

The accuracy and reduced variability of the ignition timing is also unlikely to be more than a limited player in the torque forcing function, since the firing frequency is still there. What is more likely happening is that the amplitudes of the higher order frequencies in the torque forcing function are much greater.

A

[Bevan]

Originally Posted by gmcjetpilot

Electronic ignitions are all considered about the same. Hartzell actually used Light Speed for many or most of their test.

George, I dont believe one should assume that all electronic ignitions are the same in how they affect propeller stress. There's just too many variable.

Further, Rick at Hartzell tells me the IO-360-M1A was tested with the Lasar system (and passed). He went on to say that the Lightspeed II would probably have the equivalent affect as the Lasar BUT but this statement could not be extended to any other EI.

Bevan

[Ted Johns]

Originally Posted by Andy_RR

All the spark can do is initiate combustion. A higher energy spark will result in a lesser ignition delay, but the burn rate will be more or less identical. What electronic ignition systems do (over magnetos) is advance the ignition. It is predominantly the advanced ignition that is responsible for the 'stronger power pulse'
A

Nope. The EI advance only happens at low manifold pressures, to improve economy. At high power settings, the advance is right where a mag would be, subject to individual owner calibration.

All ignition events are NOT created equal. A low power spark does not always result in complete combustion due to charge stratification, among other things. This is why a high power, longer duration spark gives more of the combustion events a greater chance to complete in the proper time to utilize the best crank angle, thus increasing power.

[Mike S]

Originally Posted by gmcjetpilot

What's assumed is electronic ignitions are equivalent. Why? TWO THINGS: One they put out a huge strong spark, which makes a stronger power pulse; Two, they are dead accurate and fire with such precision they tend to aggravate harmonics. Mag timing kind of floats around a little, and of course mags a have much weaker spark.

The Laser system uses one of the mags as a sensor, so it is subject to the same level of timing "float" as a regular non electronic setup.

To really keep the timing dead on, a pickup at the crank/flywheel is needed.

Some E.I.s---E/Pmag, I believe, (and, I think, even Light speed has the option) are timed by the use of a mag port in the accessory case instead of the crank trigger.