Complex engine management

[BadAim]

Originally Posted by Triggaaar

This is going to be tough, and great.That's easy when crusing/climbing/shallow diving etc, but when in a dogfight and doing loops etc, where your speed will be dramtically changing all the time, it must be a nightmare.

Damn Skippy! The 109 is a bear, after a 15-20 minute dogfight last night in which I shot down nothing, I needed to teak a break and rest, because the mental workload was so high! (I'm sure that this situation will improve with familiarity)

P.S. The above is not a complaint: I love it!

[Moggy]

Originally Posted by BadAim

The boost gauge is your friend. There will be no more slamming the throttle to the firewall and flying 'till you run out of fuel. CEM is certainly a different world now.

Absolutely and if memory serves the maximum amount of time allowed with the boost plug pulled was 5 minutes with Rolls Royce engines. During the Battle of Britain, the pilot also had to record if he pulled the plug in his combat report.

[Triggaaar]

Originally Posted by Multimetal

I'm sure that over the life of this sim we'll get used to it and be rewarded with a whole new level of realism!

That's the great thing about there only being a small choice of aircraft in this initial release. We can stick to a couple of planes and learn how to fly.

[robtek]

And i bet in the "full real" online-wars there will be many, many, many "expensive" gliders.

[T}{OR]

Originally Posted by Triggaaar

This is going to be tough, and great.That's easy when crusing/climbing/shallow diving etc, but when in a dogfight and doing loops etc, where your speed will be dramtically changing all the time, it must be a nightmare.

Well, you gotta start somewhere first. In order to drive an F1 car, first you need to learn how to drive.

For everything else, Azimech is here. I don't have the time to write about all this stuff.

[Richie]

Originally Posted by SG1_Gunkan

I am having a hard time with the complex engina management. Not because of the sim, is amazing to control the engine at this detail, is because is not explained deeply in the manual.

At this point, i blow the spitfire engine very easily, and hurricane sometimes, and the BF109E is more easy but i only can get 400 km/h at low level...

The basic controls are throttle, pitch and mixture? I didn't set the mixture not the radiator, just because of the russian menus.

To start the BF109, open the fuel (yellow lever at left part of cockpit), set magnetos to M2 and press I.

The pitch directly change the helix angle with air, but be carefull to don't go too much RPM (> 2500 rpms). The normal RPM to me are 2200 RPMs. In the BF110 i am having a REAL hard time because i killed the engine easily because of my bad pitch control...

Inthe spit there is no something like pitch, i only have two position and i don't really understand, one is to slow and one is too high.

This is what i know at this moment from Complex engina management, i think is AMAZING, but i don't have any information about how to make this work well. I need your help, because it's not written in the manual.

Someone can explain me how this work?

Check out some official stats and see how fast that 109 went on the deck. It won't be as fast as it went at altitude. I found some Emil stats. Remember you don't get true air speed off of your gauges witch pick it up from air passing threw your pitot head.

http://www.battleofbritain1940.net/0013.html

[Blackdog_kt]

Originally Posted by robtek

And i bet in the "full real" online-wars there will be many, many, many "expensive" gliders.

Hahahah, so true. Although to tell you the truth, i can't wait for the "190 is uber" posts once we get that fully automatic bird

Originally Posted by BadByte

If La-5 makes it into CoD, I will not fly it with complex engine management on .
"For example, rapid acceleration required moving no less than six levers." Taken from http://en.wikipedia.org/wiki/Lavochkin_La-5

It's the same thing with all USAF fighters. To execute a simple boom and zoom bounce with the P-47 you need to:

lower the turbocharger RPM (this is like a throttle for high altitudes, but it takes time for the turbo to spool up/down and this makes it difficult to judge the fine-tuning of it all)

set the pitch/RPM for the dive

possibly lower the throttle too (if it's a long dive and you want to accelerate slowly)

close the cowl flaps (they can get damaged at high speeds, these control the cylinder temperatures)

adjust the intercoolers for the temperature you expect to meet at the lower altitudes as you dive (these control carburetor temperature: too low and it freezes and stops fuel to the engine, too high and the mixture is too lean to produce power and causes overheat in the cylinders)

adjust the oil coolers in a similar manner to intercoolers (low oil temp means the oil is thick and doesn't flow or lubricate well plus oil pressure gets high and you might burst a pipeline, high oil temp means the oil breaks apart/dissolves, lubrication is bad because the oil runs through the parts too fast and it may even catch fire)

The only help in all this is that oil temps change slower than carburetor temps and cylinder temps so you can afford to make a mistake, plus late war US aircraft usually had automatic oil cooler control.

After you do all this and dive, you can attack your target. When you pull back up from the dive to climb away you need to do all this in reverse.


Dynamic weather in the future will also make it more difficult. In ISA conditions (international standard atmosphere: an ideal, rare to see in real conditions physics model, but still close to the real thing), the ambient temperature changes 2 degrees Celsius every 1000 ft. You dive 5000ft, the air outside will be roughly 10 degrees hotter, etc, and this also has an effect on how your engine works, imagine diving on a bandit 8000ft below, that's a full 16 degrees Celsius of difference (hence the intercooler, cowl flap and oil cooler adjustments in the example above).

However, with dynamic weather we don't have an ISA atmosphere. We will also have temperature inversion layers, icing layers, cold fronts, etc. Imagine diving and having adjusted for the warmer air and then you hit a patch of cold air and don't notice because you're looking at the banding below and not the needles in the cockpit: shock cooling, carburetor icing and so on.

There's a reason that wartime pilots who got shot down and lived to talk about it usually said "i didn't even see what hit me": they had no HUD and no HOTAS and they had to keep their eyes inside the cockpit for a substantial amount of time to keep the aircraft "healthy"

Originally Posted by SG1_Gunkan

I am having a hard time with the complex engina management. Not because of the sim, is amazing to control the engine at this detail, is because is not explained deeply in the manual.

At this point, i blow the spitfire engine very easily, and hurricane sometimes, and the BF109E is more easy but i only can get 400 km/h at low level...

The basic controls are throttle, pitch and mixture? I didn't set the mixture not the radiator, just because of the russian menus.

To start the BF109, open the fuel (yellow lever at left part of cockpit), set magnetos to M2 and press I.

The pitch directly change the helix angle with air, but be carefull to don't go too much RPM (> 2500 rpms). The normal RPM to me are 2200 RPMs. In the BF110 i am having a REAL hard time because i killed the engine easily because of my bad pitch control...

Inthe spit there is no something like pitch, i only have two position and i don't really understand, one is to slow and one is too high.

This is what i know at this moment from Complex engina management, i think is AMAZING, but i don't have any information about how to make this work well. I need your help, because it's not written in the manual.

Someone can explain me how this work?

There four propeller types:

1) Fixed pitch prop: This is like in the Tiger Moth, no pitch control at all. The more throttle you give or the more airspeed the airplane picks up, the higher your RPM gets.

2) Variable pitch prop: The system used by the 109. In this you directly control the prop blade angle. This means that when your speed changes, you have to change pitch too. If you leave the prop at the same pitch, it will go to higher RPM when you are increasing airspeed and lower RPM when you are slowing down.

3) Constant speed prop: In this one you don't control the prop blade angle directly. You control something else (maybe oil pressure inside the spinner or another mechanical system). The way it probably works is that the mechanical system wants to change the angle one way, the airflow on the prop wants to change it the other way. If you balance these two things together, you get an equilibrium. So, when one of these things changes the other changes too.

This gives you constant RPM and it's the easier propeller to use (unless you have a fully automatic system, like the Fw-190 for example). If you want to do 2500 RPM you just move the controls until the gauge shows 2500 RPM and leave it there, it will automatically adjust the angle to give you this RPM.

Of course, the prop blades don't have unlimited angle travel: If you go very fast the automatic system can't change the angle anymore and RPM goes up. If you use too low throttle, there is not enough power to turn the prop and RPM goes down. But most of the time, RPM stays where you set it to stay.

4) Two-stage prop: This is probably what happens to you in the Spit. Some early Spits and Hurricanes didn't have a constant speed prop. They had a prop that only had two positions, a high RPM position for take-off and climb and a lower RPM position for cruise and dive. This is like having the 1st kind of prop (the Tiger Moth prop) but for two positions.


Apart from that, there are things you can't do in a real engine but i don't have CoD yet and i don't know if it models all of them. The most important one is don't use high throttle with low RPM.

The reason RPM gets low is because the blade hits the air with a bigger angle of attack: resistance is bigger and that's why the RPM drops, but also the propeller pushes more air and generates more power.

This is what you do for fuel economy, reduce throttle to burn less fuel and increase propeller angle of attack to make up the lost power from the lower throttle setting.

If you keep the prop angle of attack high (aka low RPM) and increase the throttle too much the engine wants to turn faster. Since the engine is connected to the prop and the prop can't turn faster due to air resistance, the engine can't accelerate either: all this pressure has nowhere else to go except on the engine and damage occurs. I think that in real airplanes, if you lower the RPM too much you can see the engine manifold pressure increasing fast without moving the throttles, this is how you realize that your RPM is too low for your throttle setting.

Now, as to how to use all this, think about propeller RPM like you do for gears in a car.

If you want to start from a stop, accelerate from a slow speed or drive uphill what do you do? You use 1st or 2nd gear. You use the gear that gives you the most RPM. This is the same for the airplane: use high RPM for take-off,climb and fast acceleration from a slow starting speed.

There is also one more case that's similar to cars. You can down-shift gears when driving downhill and you don't want to accelerate too much. You can do the same with the airplane, if you want to go slower in a dive you can lower the propeller angle of attack which will increase the RPM. This means that the propeller is facing the incoming air almost head-on: if this happens with enough throttle you will accelerate, but if you do it with low or idle throttle the propeller disk turns from the airflow's energy and not from the energy and acts like an airbrake. Just like cars however, if you go fast your RPM will increase too much and you will have to reduce it or risk damaging the engine.

The opposite happens with low RPM. In cars higher gears give you lower RPM for the same speed/throttle. If you want to go fast without burning too much fuel or if you want to accelerate better when driving downhill, you use a higher gear (lower RPM). It's the same with aircraft too, use high propeller angle of attack (low RPM) for cruise and accelerating in dives.

This is also why landings are also made at full RPM: if you close the throttle the plane slows down rapidly, if you open the throttle if accelerates rapidly. Try to fly a takeoff and landing at full RPM, then at half RPM and you'll see the difference. It's like trying to accelerate a car from 0-120 km/h and then stop at the shortest possible space without using the low gears at all but only 4th gear: it will take ages to get to the speeds where that gear is effective and when you need to stop it will also not provide any gearbox braking.

Of course, cars have 4-6 preset gears that are tested to work best with the car and you can't select the "useless" positions.
In aircraft on the other hand, you can move the pitch controls over a wide range of very small adjustments. It's like the aircraft has hundreds of gears (one of every fraction of a degree of propeller angle of attack), but not all of them are useful.

That's why operating manuals tell pilots what is the proper RPM for each phase of flight: the engine might give best acceleration at 2700 RPM, best cruise at 2500 RPM and a bit of both but not very good at 2600 RPM. The difference is that in a car you know that you can only go from 3rd to 4th gear, in the airplane you can't skip 2600 RPM and somebody has to tell you that it's not the best setting


Sorry for the long post, i hope it helps a bit.

[svanen]

Thanks for your long replys, very interesting, looking forward to learn more about this.

[Skoshi Tiger]

According to the pilots notes in the Collectors edition, the spitfire has a mechanical linkage between the mixture leaver and Throttle. The mixture leaver is on the lefthand side of the throttle I think (I'll check when I get home).

"Throttle an mixture controls - The throttle an mixture leaver (10 and 11) are fitted in a quadrant on the port side of the cockpit. A gate is provided for the throttle leaver in the take-off position and an interlocking device between the two leavers prevents the engine from being run on an unsuitable mixture" from the MK II book but from memory it looked fairly similar!)

Cheers!

[RAF74_Winger]

Won't be much use for the 109 and the two-speed props on the spit & hurri, but the way I was taught to use a CSU was "rev up, throttle back"

i.e.:

When increasing power - set the rpm first, then increase the throttle.
When decreasing power - throttle back, then adjust the prop.

Also consider that the CSU's on these big props will have a considerable amount of lag & consequent overshoot - increase throttle gradually. Also, for the spit, you'll want to make absolutely certain that the mixture is in 'Auto rich' before using very high power settings.

Hope that's of some help, I don't have the game yet so I'm just posting from previous experience.

W.