Blenheim take-off issue

[1.JaVA_Platypus]

Hi guys,

I am a fan of the new sim, Il-2 Cliffs of Dover. There are still a few issues to be resolved, but underneath the mud of many small and smaller bugs, lies a real gem. When it runs properly, it will be two or three generations ahead of Il-2 1946! I am a natural bomber pilot, flying for the red side. So naturally, I should fly the Blenheim. Starting the engines takes a little attention, but isn't too difficult. Take-ing off however is far more difficult. On the internet, I found the pilot's manual for the Blenheim V, wich should have the same engines of the Blenheim IV in the game. In the PDF, at page 33, paragraph 9 it says:

9. TAKE-OFF
(i) There is a slight tendency to swing to the right

Well, the tendency to go to the right is pretty stong. It is not possible to counter this with the rudder, altough it helps of course. It is only possible to take off when engine 2 is running at its max (but don't do that for too long) and running engine 1 for about 40pct. With the reduced power, it will take a long time before the Blenheim reaches take-off speed. So I think there is some kind of bug involved that makes the airplane go to the right far too much. I hope it can be fixed.

[242Sqn_Chap]

I have found exactly the same.

The only way to take off seems to be to run engine 1 at about 30% and 2 at full power or it swings to the right regardless of rudder.
Once airborne, changing to course pitch however, the engines revs do equalise and its Ok from then on. I havn't tried it yet but am wondering if Course pitch may help during take off also ?

Its difficult at the moment sometimes to know if something is a deliberate feature & is part of the difficult learning curve....or is a bug.

I am guessing that something may not be right here though ? (tail wheel misalignment? Torque error ?)

Perhaps somebody could post the correct way to take off in the Blenheim if its not a bug ?

[bando]

The Blennheim starts with the rudder fully trimmed to stbd. Have you corrected this?
I gave up on that cross country mission a while back and made my own mission. I never had any problems with the plane after that, but it spawns always with the rudder trimmed fully stbd so I immediately trim it neutral before even the engines start.

[242Sqn_Chap]

You are quite correct Brando.

By trimming the rudder trim full left it is possible to take off with both engines and the rudder (In the past I had to tap the brake to keep centred...but I don't if I don't use that cross country mission (something not quite right with that is there.)

Now to discover how to fly it at more than about 30% power for longer than 5 minutes without burning out the engines :-(

[Blackdog_kt]

I'm not trying to be a smart-ass here, but how do you define 30% power?

The reason i'm asking is that i see too many people used to IL2 thinking that available power = the amount of throttle travel.

This is definitely not true. A supercharged engine might actually go over the power it can stand if you push the throttles to the stops while on the ground.

Let's say we run an engine at 1 Ata, once at 1km and once at 3km. Due to the drop in outside air pressure the air getting sucked into the engine is thinner as well, when flying at 3km we need to open the throttle more than we opened it at 1km. However, if the engine runs at 1 Ata and the same RPM, it's producing the same power in both cases regardless of how far forward the levers in the cockpit are.

The reason i used Luftwaffe numbering conventions is that the RAF aircraft have an automatic regulator for the manifold pressure, which keeps boost steady during altitude changes. This means that moving the power levers selects a manifold pressure, which is then maintained by automatically varying the throttle vanes in the engine's manifold intake (as long as the engine can do it that is, if you want to achieve +8 psi boost at 30.000ft you probably won't be able to due to the low ambient air pressure).

Nevertheless, just because there is available throttle travel doesn't mean it should be used for any length of time.
It might be there just to get you off the ground safely with a heavy bomb load, but not sustainable for the long run. Or it might be something you elect to do when you're hunted down by a pack of 110s and you see some Spitfires in the distance, trying to close the gap faster and risking blowing an engine out in exchange for getting the bandits off your back.

I too have seen the radial engines (not just the Blehnheim, the G.50 and BR.20 as well) being a bit temperamental and sensitive to temperature changes. However, 30% of throttle travel can be a lot of power in many engines in the sim.
As an example, the boost levels in the RAF instruments are relative to the air pressure of a normal day on seal level, positive being above 1 bar and negative being lower than 1 bar of pressure.
When your instruments read 0 psi at 10000ftm, your engine is actually working in thin air and yet managing to produce the exact same amount of power it would at sea level. That's no small feat at all and since you get more than sea level power (it's easy to hold +2.5 in a Blenheim at 8000ft) while cruising in thinner air, you are actually going faster.