The 109... questions

[Blackdog_kt]

@ xnomad and madrebel: Excellent, thanks a lot, i will check out the documents now and the radiator indicator next time i fire up the sim.

[schnorchel]

CEM and temperature effect on @4km, set 85% pitch get 2550 RPM, RAD full open, throttle 100%( I can not find a WEP on 109E3 so far) water temp 100C, I can only get 400km/h IAS. means almost 500km/hTAS, I think it is too slow. something wrong I did?

[engarde]

As an aside, i have read that many P38's in Europe were lost on the bounce as they were difficult to quickly set up for combat trim.

Perhaps these posts were the very same difficulties discussed over evening muster back in the day?

[Winger]

Originally Posted by xnomad

@Blackdog_kt

Excellent write up.

Here's a tip:
The water radiator settings can be seen on the wing roots of the 109. There is a little rod/pin that shows the radiator settings. Lean out and look down and you'll see them. If the rod is all the way out the rads are fully open. If the rod is not visible the radiator is fully closed. If you zoom in on them you can see the settings labelled in fractions.

There should also be a degree indicator on the left wing showing the flaps position but it's not there. In the picture below it is on the right wing.
http://www.pbase.com/bertone61/image/79470175

Hey. How did you set up zoom if i may ask? Are you pressing a key and then moving the mouse? I find that pretty circumstantial and set 2 axes of my hotas to have they mouse Y-Axis and another one to toggle zoom mode. My problem with that is that i cannot seem to influence the speed in wich the zoom changes. And by default its pretty damn fast.
I would love to have the possibility to change zoom slowly and kind of "analog" by simply pressing and holding one button to zoom in and another to zoom out. Dont know if you guys know ROF. But they solved this pretty perfect. There is a setting with wich you can influence the inertia of the zoom. Is there something like that in CLOD too?

Winger

[adonys]

I've found out it's rather hard to exceed 400 IAS in Bf109E3, but sometimes you can do it.

Combat (full power settings - bold settings are your main goal):
- oil radiator almost closed 30% open (between 20-40% open, I'm modifying it all the time) - keep an eye on oil's temp all the time
- prop pitch anywhere around 90% (between 80-100%, I'm modifying it all the time, accordingly with oil rad modifications, and trying to keep the RPM in the desired area)
- throttle kept modified (accordingly with the above oil rad and prop pitch settings and trying to keep the RPM in the desired area)
- RPM around 2500 (between 2000 and 3000)
- speed over 400 IAS
- water rad fully open

Don't forget to lower/cut the the throttle in dives (and eventually ease your prop pitch too), and get it back once leveled.

Cruise (economy settings - bold settings are your main goal).
- water radiator fully opened
- oil radiator fully opened
- prop pitch 100% (between 90-100%)
- throttle around 45% (between 45-55%)
- RPM around 2000
- speed over 300 IAS
- manifold pressure as lower as you can manage it (to conserve fuel while keeping a reasonable speed)

[robtek]

Here is the howto for the 109E :
http://rapidshare.com/#!download|688...buch.pdf|16097

[Blackdog_kt]

Originally Posted by adonys

I've found out it's rather hard to exceed 400 IAS in Bf109E3, but sometimes you can do it.

Combat (full power settings - bold settings are your main goal):
- oil radiator almost closed 30% open (between 20-40% open, I'm modifying it all the time) - keep an eye on oil's temp all the time
- prop pitch anywhere around 90% (between 80-100%, I'm modifying it all the time, accordingly with oil rad modifications, and trying to keep the RPM in the desired area)
- throttle kept modified (accordingly with the above oil rad and prop pitch settings and trying to keep the RPM in the desired area)
- RPM around 2500 (between 2000 and 3000)
- speed over 400 IAS
- water rad fully open

Don't forget to lower/cut the the throttle in dives (and eventually ease your prop pitch too), and get it back once leveled.

Cruise (economy settings - bold settings are your main goal).
- water radiator fully opened
- oil radiator fully opened
- prop pitch 100% (between 90-100%)
- throttle around 45% (between 45-55%)
- RPM around 2000
- speed over 300 IAS
- manifold pressure as lower as you can manage it (to conserve fuel while keeping a reasonable speed)

Excuse me for saying so, but i tend to do cruise a bit different, lower the throttle and then drop the RPM. Reducing the pitch has the effect of raising the manifold pressure again, so i re-adjust the throttle which again affects the RPM (throttle affects RPM only on the German aircraft and on the RAF aircraft that don't have a constant speed prop, aircraft with a CSP keep the RPM steady on their own) and so on...but after a couple of back and forths it settles into a steady situation.

However, i use lower RPM (in fact i use the settings stated in the manual) with 1.2 Ata, since i think that RPM has a bigger effect on fuel consumption. For example, the Hurricane has a "cruise mode lock" on the propeller once you pull it fully back and it uses 1800 RPM or so for extra fuel economy.

Using 1.2 Ata, 2300 RPM and bit of trim i can easily cruise at 380-400 km/h with the water rads full open and the oil rads about 70% open.

The reason i'm using mid-range values for MP and RPM instead of high RPM with low MP is that every single aircraft checklist i've seen (both for combat and civilian planes) tells the pilots to use lower RPM in cruise to conserve fuel.

MP also has an effect in fuel consumption as the more air getting sucked into the engine the more fuel the metering valves/injection system/carburetors drop into he mix.

The thing is that using lower RPM lets you get more speed from the same amount of MP, as long as we're talking about cruise in level flight. After all, the reason RPM drops is because the prop is in coarse pitch and getting a bigger bite out of the air, making it more efficient for straight and level flight.
It's like going to 6th gear on a car when driving on a highway and dropping your RPM to 2500 without changing the amount of throttle you use: you won't accelerate/decelerate fast if you change how much you press the gas pedal, but you are sure getting where you want to go fast and with lower fuel burn, as long as you don't need fast responses from the engine.

Going low Ata with RPM is like doing the same speed in that car but instead of using 6th gear and 2500 RPM you use 4th gear and 6500 RPM: it's going to burn much more fuel and it's not even sure you'll get the same speed in the end.

The way it works is very different, but the end results are very similar so that it's easy to think of prop pitch and RPM like gears in a car. For example, whenever the car goes uphill we down-shift to increase our RPM and the engine's responsiveness, whenever the aircraft climbs we can go to high RPM to do the same.
During slow driving we use low gears that give us high RPM and fast response at low speeds, during the landing circuit we use fine pitch and high RPM for the same reason. Just like lifting your foot from the gas pedal will slow your car down via the gears if you are in low gear, using high RPM with low MP in an aircraft will do something similar. In this case however the braking is not only a function of the gearbox absorbing part of the energy, but mostly the propeller acting as an airbrake.

If you are on fine pitch/high RPM and the engine is not making enough power to turn that prop then it's getting turned by the air and windmills while at fine pitch (ie, the prop is almost flat, face-on to the incoming airflow)-->extra drag.

So, by using that analogy you can think of many useful scenarios.
What do you do to speed up in the dive faster or just let it pick up speed more efficiently? The same thing you'd do to speed up when driving a car downhill, progressively switch to higher gears/lower RPM while pressing the gas pedal or just go high gear and let it roll on its own. In our aircraft, this means coming back on the RPM a bit.

What if you want to go slow in the dive? Well, it's similar to what you'd do to keep your car from speeding up too much when driving downhill, use a lower gear/higher RPM while coming off the gas pedal. So, just chop the throttle and go to high RPM and the prop windmilling effect will give you the drag you need.

I'm not an expert or a real pilot and i certainly don't want to play it smart on you, i'm just surprised that your method is so different and that makes me want to compare notes.
You know, like a couple of pilots talking about "how to get that extra bit of performance" between sorties. Cheers

[Winger]

Originally Posted by Blackdog_kt

Excuse me for saying so, but i tend to do cruise a bit different, lower the throttle and then drop the RPM. Reducing the pitch has the effect of raising the manifold pressure again, so i re-adjust the throttle which again affects the RPM (throttle affects RPM only on the German aircraft and on the RAF aircraft that don't have a constant speed prop, aircraft with a CSP keep the RPM steady on their own) and so on...but after a couple of back and forths it settles into a steady situation.

However, i use lower RPM (in fact i use the settings stated in the manual) with 1.2 Ata, since i think that RPM has a bigger effect on fuel consumption. For example, the Hurricane has a "cruise mode lock" on the propeller once you pull it fully back and it uses 1800 RPM or so for extra fuel economy.

Using 1.2 Ata, 2300 RPM and bit of trim i can easily cruise at 380-400 km/h with the water rads full open and the oil rads about 70% open.

The reason i'm using mid-range values for MP and RPM instead of high RPM with low MP is that every single aircraft checklist i've seen (both for combat and civilian planes) tells the pilots to use lower RPM in cruise to conserve fuel.

MP also has an effect in fuel consumption as the more air getting sucked into the engine the more fuel the metering valves/injection system/carburetors drop into he mix.

The thing is that using lower RPM lets you get more speed from the same amount of MP, as long as we're talking about cruise in level flight. After all, the reason RPM drops is because the prop is in coarse pitch and getting a bigger bite out of the air, making it more efficient for straight and level flight.
It's like going to 6th gear on a car when driving on a highway and dropping your RPM to 2500 without changing the amount of throttle you use: you won't accelerate/decelerate fast if you change how much you press the gas pedal, but you are sure getting where you want to go fast and with lower fuel burn, as long as you don't need fast responses from the engine.

Going low Ata with RPM is like doing the same speed in that car but instead of using 6th gear and 2500 RPM you use 4th gear and 6500 RPM: it's going to burn much more fuel and it's not even sure you'll get the same speed in the end.

The way it works is very different, but the end results are very similar so that it's easy to think of prop pitch and RPM like gears in a car. For example, whenever the car goes uphill we down-shift to increase our RPM and the engine's responsiveness, whenever the aircraft climbs we can go to high RPM to do the same.
During slow driving we use low gears that give us high RPM and fast response at low speeds, during the landing circuit we use fine pitch and high RPM for the same reason. Just like lifting your foot from the gas pedal will slow your car down via the gears if you are in low gear, using high RPM with low MP in an aircraft will do something similar. In this case however the braking is not only a function of the gearbox absorbing part of the energy, but mostly the propeller acting as an airbrake.

If you are on fine pitch/high RPM and the engine is not making enough power to turn that prop then it's getting turned by the air and windmills while at fine pitch (ie, the prop is almost flat, face-on to the incoming airflow)-->extra drag.

So, by using that analogy you can think of many useful scenarios.
What do you do to speed up in the dive faster or just let it pick up speed more efficiently? The same thing you'd do to speed up when driving a car downhill, progressively switch to higher gears/lower RPM while pressing the gas pedal or just go high gear and let it roll on its own. In our aircraft, this means coming back on the RPM a bit.

What if you want to go slow in the dive? Well, it's similar to what you'd do to keep your car from speeding up too much when driving downhill, use a lower gear/higher RPM while coming off the gas pedal. So, just chop the throttle and go to high RPM and the prop windmilling effect will give you the drag you need.

I'm not an expert or a real pilot and i certainly don't want to play it smart on you, i'm just surprised that your method is so different and that makes me want to compare notes.
You know, like a couple of pilots talking about "how to get that extra bit of performance" between sorties. Cheers

Excellent. What are you in RL? Teacher? NO - should consider changing your job. Thanks for the writeup!

Winger

[adonys]

Originally Posted by Blackdog_kt

Excuse me for saying so, but i tend to do cruise a bit different, lower the throttle and then drop the RPM. Reducing the pitch has the effect of raising the manifold pressure again, so i re-adjust the throttle which again affects the RPM (throttle affects RPM only on the German aircraft and on the RAF aircraft that don't have a constant speed prop, aircraft with a CSP keep the RPM steady on their own) and so on...but after a couple of back and forths it settles into a steady situation.

it's the same thing I said. I was writing from memory (haven't checked exactly in the game), yet I've said throttle back and low RPM (around 2000, but actually going down towards 1800), if the high prop pitch rises the RPM, then you'll lower it until you get around the needed RPM.

Which is the RPM you're using for cruising, isn't something between 1800-2000?

The two important causes for fuel consumption are throttle RPM and fuel pressure. I said throttle RPM, because RPM going higher because of the wind forcing a faster rotation of the propeller shouldn't accelerate your fuel consumption. using the same car analogy, if you let it loose downhill, faster rotation of wheels because of the gravity won't make you consume more fuel to acquire it.

That's what I believe, I'm also no pilot, just using logic and knowledge. So, don't worry, I don't have any problem arguing or being corrected (I'm not stupid enough to think I'm always right, I'm not God), on contrary, these kind of discussions improves the knowledge of all of us, and that's a good thing, isn't it?

[Geronimo989]

Ok a quite simple and maybe stupid question: Does more RPM always mean more power on the 109, with the risk of breaking the engine when exceeding the limit? Or do you get maximum power when staying in certain RPM range (2500) and you actually LOSE power when you exceeding it?