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Old 04-13-2011, 06:19 PM
utu utu is offline
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Quote:
Originally Posted by Dutch_851 View Post
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!
If you can climb at 10000 ft without any stutter then you have found the little trick. Was it smooth?
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