Quote:
Originally Posted by utu
No, it has only 2 position mixture: rich and lean. Lean is for cruise, because the Spit has huge amount of fuel consumption and this is a good compromise between horizontal speed, temperatures and fuel consump. The mixture is not critical like a Cessna or other small planes, where you have to listen to the engine and then pulling or pushing the mixt lever to find the right mixture. An engine of 27 liters works different. Tried at at +4 and +2 boost, even at high, med and low rpm: climbing full CEM over 5000ft means engine's fail with Spit mkIIa (rotol prop).
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Well, I've just tried it with both Mk1a and MkIIa Spits and got to 10000ft and back down again without mishap.
Once started on the ground in rich mixture, radiator fully open, allow engine to warm up to 80 degrees or so with brakes on and 0 boost.
Immediately taxi to runway and take-off at +5 boost.
As soon as you take-off, lower boost to +4 and pitch to 2650, and set engine to lean mixture.
After building up some speed, trim for climb at 160 - 180mph. Obviously IAS decreases as you climb.
Then it seems to be a balancing act between prop pitch and boost.
Coarsening the prop pitch keeps oil temp under control, lower revs=cooler oil temp, higher revs=higher oil temp. Keep to about 70 degrees.
Engine boost keeps water temp under control, keep to about 90 degrees.
I didn't go into the red boost zone at all much on the climb, so no more than +4 and sometimes as low as 0 boost.
All this was with coolant rad fully open.
After reaching 10000, I chopped the throttle and changed to rich mixture to keep the motor running, closed the coolant rad and pretty much split-'S'-ed to the deck.
For a trickle of power for landing I had to go back to lean mixture and back again to rich on chopping the throttle once on the ground again for the taxi.
Hope this helps!
