Optimizing flight/speed with CEM

[Bulau]

Well, I've read that there is a mixture bug that affects the Hurricanes, perhaps also the Spits, wherein the mixture control is bass-ackwards. So you might try setting mixture to RICH and see if that actually gets you LEAN.

My understanding of coarse pitch is that it's for cruising economy. If you're trying to catch up, use fine pitch.

[Vengeanze]

Guess you opened up radiators. Otherwise that will overheat your engine and break it a couple of minutes after take off.

Otherwise your to procedure looks ok.
You could add like 20 clicks on nosedown trim to get your aft up faster.


Edit: Actually no need to switch on Magnetos in CloD. Just the fuel cock and 15% throttle and hit I. After that u can run through the check list while the engine warms up.

[prophet106]

Thanks for the replies chaps (and that lengthy one Woarmonger, excellent).

Yes i open the radiator fully for take off/landing and keep it at about halfway during flight. i'm still slightly at a loss as to the exhaust though. i haven't even contemplated playing it online yet. just working my way through the campaign (hence having to use the spit). i'll try doing as you say with regards to keeping low after takeoff and building up airspeed before climbing.

yes the first couple times i took off for an interecption i keep climbing in fine pitch on full power. It either pops the piston head or blows the carb.

Thanks again. more innane questions to follow im sure !

[Blackdog_kt]

Whoarmonger got most of it and you seem to have a good grasp on things, so i'll only add two things:

Mixture: Not all people agree it's a bug, because it was reversed in the real aircraft too. This is a carry-over from manual mixture systems, so that by pulling the throttle back the detent on the throttle lever will also pull the mixture back into rich to prevent fuel starvation.

Try to think in terms of what you see the controls doing in the cockpit and not what your key bindings are titled and you'll be fine: auto-rich mixture is with the lever fully back and auto-lean with the lever fully forward.

Prop pitch: Think of it like gears in a car. The two-stage prop only gives you two gears (fine and coarse pitch) so it's like you only have 1st and 4th gear, but they do have a pretty wide power band. In fact i find these Spits pretty easy to manage compared to a 109 which has fully adjustable but still manual pitch.

Use fine pitch just like you would use 1st gear in your car: Slow climbs, low speeds, to limit your speed in a dive (just throttle back a bit to avoid over-revving it), when you want faster response to throttle changes (both decrease and increase) like for example when taking off/landing. It's good to have it on fine for the landing approach in case you need to go around too.

Use fine pitch like a 4th gear: Fuel economy during cruise, attaining your top speed, accelerating in the dive and climbing while at high speed (switching to fine for every climb is like driving on the highway at 140km/h and downshifting to 2nd gear whenever you see a small upwards slope on the road: the torque sure is enough to climb it, but you are bleeding off speed like crazy).

Keep in mind that changing the pitch will also affect manifold pressure, even more so with these props because the pitch change and resulting torque change is quite big: boost will rise when setting coarse pitch so you might need to throttle back a bit, in a similar fashion it will drop when going to fine pitch and you might need to throttle up a bit.

As you can see, it's mostly situational and there's not a hard and fast rule. In fact, there are cases when flying at fine pitch all the time severely limits your performance, like for example trying to catch a 109 in a dive: fine pitch will not only cause the RPMs to pick up and force you to throttle back, it also gets to a point during the dive that the prop creates considerable drag, due to the prop blades being almost face-on to the incoming airflow. It's like having a disc-shaped airbrake in front of you.

Switching to coarse pitch in such a case presents a smaller "head-on" cross section of prop blades in regards to oncoming airflow and lets you pick up more speed.

[EZ1]

You may want to keep that radiator open a bit more in flight--85% maybe. I just closed mine to 50% and it blew a gasket in about a minute. LOOK at the temp guage.

[prophet106]

Thanks again for the tips chaps, invaluble

EZ1 i normally fly with my rad about 70% closed, it seems fine at that setting ? Temperature normally sits at around 100

I do have another question with regards to airspeed; Just flown the mission on campaign where you fly as #2 to the wing-co to take photos of the jerry airfield near calais. You both fly at low level all the way to the French coast. Now if i am flying manually he slowly draws away from me. If i switch to autopilot he manages to catch up again. What am i doing wrong ? I have -

- Airscrew in coarse pitch
- Rad about 70% closed (temp sitting comfortably on about 100 IIRC)
- Fuel rich (assuming it's rich, if i switch it back the other way it slows down)
- Elevators trimmed so it's almost flying level (apart from the torque which needs a bit of left aerlieon)
- Throttle pretty much at 100%

When the autopilot takes over no levers change position ? However those exhaust traces do disappear. Next time somebody is flying a spit would they mind quickly switching the cockpit off and seeing if they still get the slight smoke from the exhaust ?

Thanks again

NB - Bagged two 109's and a 110 yesterday for the first time flying with CEM. Nice feeling

[touchdown42]

Just an idea, perhaps you've trimmed nose heavy and the smoke comes from neg G carb overflow.

What if you pull the Spit into a slight climb? Still black smoke then?