Lycoming O-1230 Flat-12 Aircraft Engine

[Guest deanfi]

new one to me ,  its a old engine " The Lycoming O-1230 hyper engine"

 

very interesing site

 

https://oldmachinepress.com/2018/04/20/lycoming-o-1230-flat-12-aircraft-engine/

 

 

[skippydiesel]

Very interesting. Thanks

 

 

[facthunter]

Long cranks with lots of cylinders hanging off them are hard to manage design wise for torsional harmonics as the crankshaft a relatively long and light unit. Most aero engines don't allow for much development or else the original design was too heavy. An aero piston engine is a contest between LIGHTNESS and producing power reliably for a reasonable design life.  Nev

 

 

[Guest deanfi]

I imagine cyclinder cooling on the back half would be problematic, it was a bit of a problem on the Lycoming flat 8 in the commanche though I believe they overcame it with better ducting

 

 

[Thruster88]

I imagine cyclinder cooling on the back half would be problematic, it was a bit of a problem on the Lycoming flat 8 in the commanche though I believe they overcame it with better ducting

 

Not a problem with liquid cooling

 

 

[Guest deanfi]

Not a problem with liquid cooling

 

Duh !

 

I was having a senior's moment thinking about  the wrong engine

 

 

 

[skippydiesel]

Long cranks with lots of cylinders hanging off them are hard to manage design wise for torsional harmonics as the crankshaft a relatively long and light unit. Most aero engines don't allow for much development or else the original design was too heavy. An aero piston engine is a contest between LIGHTNESS and producing power reliably for a reasonable design life.  Nev

 

Its only 7 cylinders long, however I do agree with you.

 

Strange how they went to so much bother to  design a very flat/low frontal area engine and then stuck a whacking great magnito & starter motor on top, completely screwing up the original concept

 

 

[facthunter]

FLAT motors don't share crankpins, like VEE motors and radials do. Crankshaft "stiffness" is always an issue , creating  "don't use" rpms to avoid harmonics wrecking the show.  Also harms redrives. quills etc..Nev

 

 

[Geoff_H]

Actually as a general rule speed harmonics tend to reduce dramatically as the number of cylinders increases.  I remember being taught in 3rd year of degree that a V12 was regarded as the first "fully" balanced engine, well the vibrations were considered insignificant.  I don't know about this engine but I am not about to get the books out to calculate the effectiveness of this configuration.  

 

Interesting to note that there is a theory that a 'square 4" with contra rotating shafts should be considered extremely well balanced,. mmmm how heavy would that be?

 

 

[Mike Borgelt]

Radial engines are good. Next time you see one have a careful look. Most of it is power producing bits (cylinders).

 

 

[Guest deanfi]

Quite interesting old nasa film about propeller whirl instability,  Start around the 2 min mark

 

https://youtu.be/j6Q5ggtV-y8

 

 

[pmccarthy]

Actually as a general rule speed harmonics tend to reduce dramatically as the number of cylinders increases.  I remember being taught in 3rd year of degree that a V12 was regarded as the first "fully" balanced engine, well the vibrations were considered insignificant.  I don't know about this engine but I am not about to get the books out to calculate the effectiveness of this configuration.  

 

Interesting to note that there is a theory that a 'square 4" with contra rotating shafts should be considered extremely well balanced,. mmmm how heavy would that be?

 

Ariel square four was a quite successful bike, used by police.

 

 

[facthunter]

It's smooth but not without problems. The reversing of the rotation does  cancel out a lot of forces. If you seek challenges play with one.. Nev

 

 

[facthunter]

Torsional harmonics are generally not felt  outside of the engine but really play havoc  with the life of it if not taken into account with harmonic balancers or "live" Counterweights and/or avoiding the critical RPM settings.. There was a lot of promoting of the V 12 configuration at times but it's not immune from the problem of the crankshaft length/thickness ratio issue (Stiffness) It has a good piston mass inertia/flywheel effect  where only a couple of Pistons are stopped at any point in time as compared with any in line or flat 4 which are the worst. where all  are stationary at the same time, twice per revolution.. That could be what the lecturer was referring to and there is an optimum angle for the Vee for that effect to be best achieved.. Nev