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XyZspineZyX
10-11-2003, 09:56 AM
I've just started a campaign with CEM switched on, and I'm still a little confused by prop. pitch settings. I understand it's like gears, but (a)which way is low gear and which way is high? I assume that 0% prop pitch is like 1st gear, and 100% is high gear.

I notice setting lower prop pitch acts like an air brake too - is this just like slowing down with gears or am I missing something?

During a fight, when speed is changing a lot, is it worthwhile changing pitch? What should I set it at?

XyZspineZyX
10-11-2003, 09:56 AM
I've just started a campaign with CEM switched on, and I'm still a little confused by prop. pitch settings. I understand it's like gears, but (a)which way is low gear and which way is high? I assume that 0% prop pitch is like 1st gear, and 100% is high gear.

I notice setting lower prop pitch acts like an air brake too - is this just like slowing down with gears or am I missing something?

During a fight, when speed is changing a lot, is it worthwhile changing pitch? What should I set it at?

XyZspineZyX
10-11-2003, 10:18 AM
Still can't work it out. I get better acceleration and top speed at 100% pitch - all lower settings just make it fly worse. What's the point?

XyZspineZyX
10-11-2003, 10:40 AM
100% is like 1st gear. 95%-85% is like 2nd and so on...

I used to fly with auto, but the response is definitely better with manual control. It's like anything else, it takes time to get used to.

Cheers,

CrazySchmidt.

(Have been here from the beginning, will be here till the end)

XyZspineZyX
10-11-2003, 10:40 AM
Bnej_03 wrote:
- I've just started a campaign with CEM switched on,
- and I'm still a little confused by prop. pitch
- settings. I understand it's like gears, but (a)which
- way is low gear and which way is high? I assume that
- 0% prop pitch is like 1st gear, and 100% is high
- gear.
-
- I notice setting lower prop pitch acts like an air
- brake too - is this just like slowing down with
- gears or am I missing something?
-
- During a fight, when speed is changing a lot, is it
- worthwhile changing pitch? What should I set it at?
-
-

The car gear thing isn't really a very helpful analogy. Further confusion is caused by the game terminology, which is the same for variable pitch (VP) systems and constant speed (CS) propellers.

100% 'prop pitch' is either fine pitch (VP) or max engine rpm (CS), and 0% 'prop pitch' gives the coarsest pitch (VP) or min rpm (CS).

Most of the ac in FB use CS propellers (109 & 190 don't, and the TB-3 has a simple fixed pitch prop). In a CS propeller the pilot schedules the rpm at which the engine is to run, the propeller adjusts the propeller pitch so that the engine runs at that speed. Setting a higher speed will cause the angle to fine off a little sp that the prop spins faster, and setting a slower speed will coarsen the blade angle to increase the load on the prop and slow it down. Changes in airspeed will be automatically adjusted for: going faster will result in a coarser blade angle, going slower, a finer angle.

With a CS propeller the 'prop pitch' is just another power lever. You want it at 100% for take-off and combat. 90% is about right for normal climbs and cruising can be done at 50-75%. Running the engine at lower rpm doesn't wear it out as quickly and, more importantly in FB, keeps the temperature down.

You do slow down better with a low prop pitch setting, however, the reverse should be the case once the throttle is closed. This might be corrected in 1.2.

In a fight you should leave pitch at 100% to give max power. I've seen some suggestions that playing with pitch can help with turning, diving etc. It shouldn't do. If you're doing anything which requires max power, and everything, apart from slowing down quickly (if you really want to do that), does require power. To slow rapidly and avoid overshooting it will help to cut the pitch along with the throttle, however, as said above, this is wrong and may well change.

With CS equipped ac you need to set 100% for take-off, combat and landing (ready for any overshoot). Do other climbs at 85-90% and cruise around 60%. That's all you need to know to start with.

In a 190 the auto system works well, so leave it in auto and that's all you need to know. The same ought to be true of the 109, but isn't. If you need to ask then it's probably best to leave the 109s in auto also, but be aware that you can get better performance if you play with the prop pitch. If you were talkin about 109s post again and I'll tell you what I know /i/smilies/16x16_smiley-wink.gif

Kernow
249 IAP

XyZspineZyX
10-11-2003, 10:44 AM
The higher the percentage of the prop pitch, the shallower the angle at which the propellor blades meet the air as they spin. At 0% they are as close to pointing directly forwards as possible. That means that at 100% pitch, the blades aren't at as steep an angle as they spin which means that they can spin faster (think of a paddle moving through water - if it's side on and presents a low profile it slides through easily, if the flat face is in the direction of motion then it's way hard to move and goes way slowly).

Power output of the engine is a function of revs per minute: the higher the rpm, the higher power output you'll get. If it goes too high though, you'll blow the engine up. Most of the engines in FB (and this is really general, so don't get upset if it's not accurate for all) can handle around 2500 rpm with no real trouble. Much more than 3000 rpm will destroy a 109 engine (for instance) in a few seconds.

Lower pitch is better for fuel economy, but awful in combat.


In combat you want it as high as possible without blowing the engine. You can either monitor it really closely and keep changing it to keep it high but not too high, OR set it at a safe level and deal with the fact that you're not going to get as much power as you otherwise could but at least you can concentrate on other things.



--

That's my understanding of it, anyway. If I'm wrong, I'd certainly appreciate someone pointing that out.

There's a good article on it here: http://www.avweb.com/news/columns/182082-1.html

XyZspineZyX
10-11-2003, 11:06 AM
I think the car transmission analogy still holds:

Fixed Pitch prop: There's only one gear ratio.

Variable Pitch prop: Manual transmission. 100% is the lowest gear, 0% the highest.

Constant Speed prop: Auto transmission. 100% is like combat/power/sports setting; 50% is like the economic/cruise setting.

Hope this helps.

XyZspineZyX
10-11-2003, 11:55 AM
Thanks for the help people! I think I have it sorted now. It's certainly interesting managing prop pitch manually in the 109, I managed to kick the 109K4 up to 600km/h IAS at sea level for about 10 seconds in level flight (20km/h over the object viewer max), and I held it at 580 for a couple minutes too. Letting the engine rev. at 2800 for a minute certainly gives the beast a kick for acceleration too!

I was a bit confused at the difference between the 109s and the other planes, but it all makes sense now.

On the Russian planes, I like being able to get the extra boost below 1000 by using 120% rich too.

XyZspineZyX
10-11-2003, 02:53 PM
It seems to increase in speed slowly.....not all at once. In fact in the Jug in some cases like if you go from say..100% to 80 it will drop first then start to pick up....actually that makes a lot of sense..LOL.. I like the way all the CEM is modeled in this sim.....

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XyZspineZyX
10-11-2003, 03:11 PM
Also, the higher the altitude, the thinner the air. Therefore adjust prop pitch to try to catch more air to keep speed. If you lower prop pitch at low altiudes, watch your RPM's, especially on the 190's and the 109's. S!

XyZspineZyX
10-11-2003, 03:30 PM
The 190s used a CS propeller in automatic and in manual. The 109 behave basically like a CS propeller only in automatic.