v12 or v10

[saviour stivala]

A ‘fork and blade’ con-rod design chose will eliminate any possibility of the engine being a ‘boxer’.

[echedey]

so would the crankshaft of the v12 have to be flat or cross crankshaft?

and the arrangement of the cylinders would have to be what I think is going to be the best 60º, as my thought was 75º like ferrari.

[Jolle]

so would the crankshaft of the v12 have to be flat or cross crankshaft?

and the arrangement of the cylinders would have to be what I think is going to be the best 60º, as my thought was 75º like ferrari.

For racing engines, the solution for the highest power is even firing intervals per exhaust heather. From that you’ll get your crank offset.

[Tommy Cookers]

so would the crankshaft of the v12 have to be flat or cross crankshaft?

neither

every 60 degree V12 ever made has a 240 degree crankshaft - ie 3 planes equally spaced (like every inline 6 cylinder)

see this https://www.enginehistory.org/members/a ... Evol.shtml
the diagram the author calls it a 6 throw crank

[echedey]

in the star can be

[J.A.W.]

so would the crankshaft of the v12 have to be flat or cross crankshaft?

neither

every 60 degree V12 ever made has a 240 degree crankshaft - ie 3 planes equally spaced (like every inline 6 cylinder)

see this https://www.enginehistory.org/members/a ... Evol.shtml
the diagram the author calls a 6 throw crank

The author of that article appears unaware of the concept of "flat" or "cross" plane orientation
of crank-throws, since if disposed at a regular 120 degrees, whether a 3, or a "6 throw crank",
its a 'tri-plane' variant of a "cross" type arrangement, whereas a "flat" plane is at zero/180/360.

"Cross" plane effectively means any 'off angle' orientation, rather than straight-line or "flat".

Case in point, Laverda initially built their 3cyl with a 180 degree "flat" 3 throw crank, but later
introduced a more usual 120 degree 'tri-plane' 3 throw unit.

The author of that article ignores 'master-slave' conrod set-ups, & blithely misapprehends the
dynamics, in particular seemingly dismissing the "flat plane" 4 throw Napier Lion crank as a
typical 'inline 4' balance-wise, despite the fact that it was a 12cyl engine, with 3 banks disposed
at 60 degrees in a 'broad-arrow', or semi-W arrangement.

See the article linked below, for a recent well-written dissertation of these particulars:

http://enginehistory.org/Piston/Napier/ ... onHx.shtml

[J.A.W.]

...every 60 degree V12 ever made has a 240 degree crankshaft
- ie 3 planes equally spaced (like every inline 6 cylinder)

What about this (ok, 180 degree) 'V12' design then, T-C?

These crank-throws appear atypical, & in contravention of your assertion?



Note: its a 2-stroke so all the pistons going down - are on the combustion stroke..

[Tommy Cookers]

...every 60 degree V12 ever made has a 240 degree crankshaft
- ie 3 planes equally spaced (like every inline 6 cylinder)

What about this (ok, 180 degree) 'V12' design then, T-C?
These crank-throws appear atypical, & in contravention of your assertion?
Note: its a 2-stroke so all the pistons going down - are on the combustion stroke..

this (the Nomad) crankshaft is a 6-plane type
found ie normal in 12 cylinder 2 strokes (eg diesels) - to give the desired 12 firings per rev (not 6 paired firings)
6 planes as if the usual 12 cyl crankshaft has been cut at the mid-point and one half rotated 180 deg before rejoining
the Crecy (90 deg) of course has this type

I was trying to help the OP by keeping things simple

[Tommy Cookers]

.... a 240 degree crankshaft - ie 3 planes equally spaced (like every inline 6 cylinder)
see this https://www.enginehistory.org/members/a ... Evol.shtml
the diagram the author calls it a 6 throw crank

"Cross" plane effectively means any 'off angle' orientation, rather than straight-line or "flat".

The author ... misapprehends the dynamics ...dismissing the "flat plane" Napier Lion as a typical 'inline 4' balance-wise

http://enginehistory.org/Piston/Napier/ ... onHx.shtml

both your statements above are .... wrong

the Lion's unbalanced (ie not cancelled internally) inertia forces are ......
just about the same as an equivalent 'flat-crank' 90 deg V8 ie matching capacity etc - eg the Hispano-Suiza(s)
so the (peak) vibratory forces (essentially 2nd order) are just about the same
about double those of a notional 'third of a Lion' flat-crank 4
ie quite a lot - especially compared to straight 6s straight 8s and V12s
the 'flat-crank' inline always has non-cancelling 2nd order inertia forces due to the effective changes in rod length


yes that's a good article on the Lion .... but .....

NA Lion on 10:1 CR & c.100 Octane fuel more efficient than supercharged engines on standard fuel of 50/60 Octane
no surprise there !
(Benzole was Benzene, Toluene and Xylene(s) - then add TEL - so very high 'Octane')
later in WW1 US-sourced c. 50 Octane fuel (replacing our E Indies fuel) forced lowered CR pistons eg 5:1 CR
we now know Albert Ball etc hoarded old pistons and babied engines unless at altitude
there were no ONs till 1930ish

the airlines wanted the Jupiter - eg because of ease of servicing (only removing the cylinder needed)
both Jupiter and Lion were toast when everyone else started making alloy heads with shrunk-in valve seats c.1926

[echedey]

This has me with melted and is driving me crazy because the mathematical formula tells me that I have to divide 720º / number of cylinder, and those are the degree that have to have the crankshaft 4 cylinder 180º 5 cylinders 155º degrees, 6 cylinders 120º degrees, 8 cylinders 90º degrees, 10 cylinders 72º degrees 12 cylinders 60º degrees but the crankshaft is supposed to go to 120º degrees I think if I'm not mistaken.

[Jolle]

This has me with melted and is driving me crazy because the mathematical formula tells me that I have to divide 720º / number of cylinder, and those are the degree that have to have the crankshaft 4 cylinder 180º 5 cylinders 155º degrees, 6 cylinders 120º degrees, 8 cylinders 90º degrees, 10 cylinders 72º degrees 12 cylinders 60º degrees but the crankshaft is supposed to go to 120º degrees I think if I'm not mistaken.

What do you mean with “the crankshaft suppose to go to 120 degrees”?

[Tommy Cookers]

This has me with melted and is driving me crazy because the mathematical formula tells me that I have to divide 720º / number of cylinder .... 12 cylinders 60º degrees but the crankshaft is supposed to go to 120º degrees I think if I'm not mistaken.

the crankshaft planes are notionally 0 deg 240 deg 480 deg 480 deg 240 deg 0 deg
viewed from an end this looks like 0 deg 240 deg 120 deg 120 deg 240 deg 0 deg

though we think of 120 deg firing intervals each crank pin is in rotation 240 deg after the previous pin

[J.A.W.]

.... a 240 degree crankshaft - ie 3 planes equally spaced (like every inline 6 cylinder)
see this https://www.enginehistory.org/members/a ... Evol.shtml
the diagram the author calls it a 6 throw crank

"Cross" plane effectively means any 'off angle' orientation, rather than straight-line or "flat".

The author ... misapprehends the dynamics ...dismissing the "flat plane" Napier Lion as a typical 'inline 4' balance-wise

http://enginehistory.org/Piston/Napier/ ... onHx.shtml

both your statements above are .... wrong

the Lion's unbalanced (ie not cancelled internally) inertia forces are ......
just about the same as an equivalent 'flat-crank' 90 deg V8 ie matching capacity etc - eg the Hispano-Suiza(s)
so the (peak) vibratory forces (essentially 2nd order) are just about the same
about double those of a notional 'third of a Lion' flat-crank 4
ie quite a lot - especially compared to straight 6s straight 8s and V12s
the 'flat-crank' inline always has non-cancelling 2nd order inertia forces due to the effective changes in rod length


yes that's a good article on the Lion .... but .....

NA Lion on 10:1 CR & c.100 Octane fuel more efficient than supercharged engines on standard fuel of 50/60 Octane
no surprise there !
(Benzole was Benzene, Toluene and Xylene(s) - then add TEL - so very high 'Octane')
later in WW1 US-sourced c. 50 Octane fuel (replacing our E Indies fuel) forced lowered CR pistons eg 5:1 CR
we now know Albert Ball etc hoarded old pistons and babied engines unless at altitude
there were no ONs till 1930ish

the airlines wanted the Jupiter - eg because of ease of servicing (only removing the cylinder needed)
both Jupiter and Lion were toast when everyone else started making alloy heads with shrunk-in valve seats c.1926

Of course a 'flat' plane crank has no off-angle big-end journals, it is, by definition 'flat',
& must be either zero/180/360 degrees in orientation. However, the cylinder bank angle
(if not also solely 'flat' inline angle-wise) will alter the dynamics considerably, you need
only check how a 360 degree 'flat plane' crank behaves in a zero degree twin, vs V-twin,
or various iterations of V-4/8, with either 180 or 360 cranks, in various V-angle cylinders..

Are you seriously suggesting an ~8 litre inline 4* wouldn't have vibration issues far worse than the Lion?

Napier Lion was hardly "toast" by the mid-20s, given it remained in production/service for another
20 years, & was powering world-speed & distance record machines over that period...

Nor was the Lion a 'buzzy' engine like usual* 'flat' plane 4cyl engines, certainly if it was, it would've
proven unsuitable for being run hard, in lightly-constructed aircraft & racing/LSR machines.

Even the Americans, who seemed determined to 'damn with faint praise' the example of the Lion
they had under test, remarked on the Lion's lack of vibration, though they'd mounted it rigidly..

*Sans counter-balancer palliatives.

[J.A.W.]

This has me with melted and is driving me crazy because the mathematical formula tells me that I have to divide 720º / number of cylinder, and those are the degree that have to have the crankshaft 4 cylinder 180º 5 cylinders 155º degrees, 6 cylinders 120º degrees, 8 cylinders 90º degrees, 10 cylinders 72º degrees 12 cylinders 60º degrees but the crankshaft is supposed to go to 120º degrees I think if I'm not mistaken.

Check these vids out, Boxer 6 & flat 12, same no' of crankpins see the dynamics:

[Tommy Cookers]

However, the cylinder bank angle ... will alter the dynamics considerably, you need only check how a 360 degree 'flat plane' crank behaves in a zero degree twin, vs V-twin,
or various iterations of V-4/8, with either 180 or 360 cranks, in various V-angle cylinders..

Are you seriously suggesting an ~8 litre inline 4* wouldn't have vibration issues far worse than the Lion?

Napier Lion was hardly "toast" by the mid-20s, given it remained in production/service for another
20 years, & was powering world-speed & distance record machines over that period...

again ....
a 12 cylinder is vibration-free as its pistons move via a 3 plane crank ie their acceleration vector sum is always zero
a 'flat crank' 12 cylinder engine could have zero vector sum at 1st order frequency - but never zero at 2nd order
yes if Napier had chosen banks at 120 deg (like an 'equal' 3 cyl radial) that would give zero sum 1st and 2nd order
but remember the established c. WW1 3 cylinder radial eg Anzani was 'unequal' angled just like the Lion

yes I seriously suggested the 8 litre inline 4 would have about half the vibrational energy than the whole Lion had
(of course the Lions energy is spread over notionally 3x the mass - so the amplitude of whole Lion vibration is less)
and yes - I have flown behind such (an ENMA Tigre c.8 litre inline 4 ) and it's rather smooth
anyway the tens of thousands of 'flat crank' V8s were successful at this time ie the Hispano-Suiza/Wright

propeller rotational and blade-bending vibration is perceived as 'engine vibration' and exists regardless of engine
yes the Lion arrangement giving a shorter crankshaft was less vulnerable eg to the metalisation and gearing of props
(Napier had 'invented' inline 6 car engines with crankshaft torsional resonance - and glamourised it as 'power rattle')