Tommy Cookers wrote: ↑
Sat Jan 22, 2022 7:06 pm
J.A.W. wrote: ↑
Sat Jan 22, 2022 3:12 am
"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.