He111 engines, can someone explain me why ?

[F/JG300_Gruber]

I've been asking myself these two questions for years, waiting to eventually understand by myself what the answers are but since I'm still in the dark today, I thought I'd better ask for a bit of enlightment.

 

First question is : why does the engines seems to have their torque effect reversed compared to the other German planes ? The Jumos are rotating clockwise like the Bf110 and most other german planes, yet cut the throttle in flight and you will have to apply right rudder, apply full throttle and you will have to apply left rudder. Exactly the same situation as in the Pe2 and it's counter-clockwise rotating klimov engines.

Does this has to do with the single vs twin tail-fin arrangement ? Is the port engine giving more pull than the starboard one for technical reasons ? Specific propwash effect ?

Ever since I started to fly this plane in BoS, probably back in 2015 or so, I've been wondering why this plane was steering to the right on take-off. But I recently noticed that this strange behaviour was also to be found in flight.

 

Second question : Upon crossing the 3000m mark, when the supercharger kicks into the 2nd stage, the manifold pressure increases from 1.05 ata to 1.25 ata (depending of course on throttle and rpm settings) and yet the rate of climb falls down for a couple seconds and even if it kind of recovers, it never goes higher than what you get at 2800-2900m.

If I replicate an increase of MP at lower altitude (say 2000m) from 1.05 to 1.25 ata, the increase in power output causes an immediate increase of the climb rate. So I don't understand the drop I get with the supercharger stage switch. I suppose that there is something a bit more complex than "higher MP = increased power output" in the case of a supercharger changing gear but I don't really understand what could happen to explain this.

 

Thanks for your time 

[Finkeren]

To your first question: It has to do with the way the propwash interacts with the single tail fin.

 

Reqiuem’s turorial on handling multi-engine AC explains the principle, even though it is really about the effect of losing power on one engine:

 

[Dakpilot]

I am not certain on He-111 engines but a guess, related to similar engines, would be when changing supercharger gear there is an increase in power required to drive it, this results in temporary performance drop until supercharger is working more efficiently

 

(extreme generalisation)

 

Am sure someone with more accurate knowledge will chime in

 

Cheers, Dakpilot

[F/JG300_Gruber]

To your first question: It has to do with the way the propwash interacts with the single tail fin.

 

Reqiuem’s turorial on handling multi-engine AC explains the principle, even though it is really about the effect of losing power on one engine:

 

 

Thanks Fink, however the video is showing what I'm expecting the plane to do : propwash + pushing the tail from the left side, so with the combination of the propeller torque, the nose will have a clear tendency to swing to the left requiring right rudder input to compensate, which is what is shown in the video. But in game, the plane still acts the complete opposite and yaw to the right instead.

 

 

I am not certain on He-111 engines but a guess, related to similar engines, would be when changing supercharger gear there is an increase in power required to drive it, this results in temporary performance drop until supercharger is working more efficiently

 

(extreme generalisation)

 

Am sure someone with more accurate knowledge will chime in

 

Cheers, Dakpilot

 

That could be an explanation.

 

I made a little test on a server this morning, and if I'm forcing the supercharger in 1st gear during the climb, I get a good performance up to 3500m, from this point switching back to auto makes the airplane nose up just a little. 

So maybe 3000m isn't the optimal altitude to gear change ? I remembered that from Cpt Brown book speaking about the 87D3, he kept the supercharger in 1st gear up to 3500m on his Jumo 211 J

Edited December 10, 2017 by F/JG300_Gruber

[Guest deleted@50488]

Cut what throttle ? right or left ?

 

If you cut left ( critical ) than I assume the left rolling / yawing tendency will be there.

 

Only reason for a right yawing / rolling tendency would be some weird calculation of the propwash interaction with the tail and rear fuselage ?

 

I'll have to check it, but I uninstalled IL2 :-(

 

If the swirling propwash hits the right aft fuselage panels, and rudder, with enough "intensity", since these are behind the CoG, it could contribute to overcome torque from the right engine, and make it swing to the right ( ? ), but yet, that same swirling propwash would tend to hit the horizontal tail surface from bellow, increasing it's AoA and make it rise, this causing a left rolling moment and associated yawing moment ( ? )

Edited December 10, 2017 by jcomm

[=TBAS=Sshadow14]

Twin engine planes rarely do both engines output same power..

1 engine runs most electrical and hydraulicsystems causing  Power loss
even mordern planes still have this .

In game
The 111 n 88 the Right engines use 5-25L/hour more fuel then the right depending on settings
2400 RPM 1.3ATA (Left 430L/Hour Right 455L/hour) at correct alt
 

[F/JG300_Gruber]

Cut what throttle ? right or left ?

 

If you cut left ( critical ) than I assume the left rolling / yawing tendency will be there.

 

Only reason for a right yawing / rolling tendency would be some weird calculation of the propwash interaction with the tail and rear fuselage ?

 

I'll have to check it, but I uninstalled IL2 :-(

 

If the swirling propwash hits the right aft fuselage panels, and rudder, with enough "intensity", since these are behind the CoG, it could contribute to overcome torque from the right engine, and make it swing to the right ( ? ), but yet, that same swirling propwash would tend to hit the horizontal tail surface from bellow, increasing it's AoA and make it rise, this causing a left rolling moment and associated yawing moment ( ? )

 

Cutting both. The video was about flying on one engine, but my question is for standard flight with both engines in any phase of the flight (take off, climbing and so on).

I'm trying to understand if something could justify that the He111 behaves like a pe2 despite having engines rotating in the opposite direction. 

 

 

Twin engine planes rarely do both engines output same power..

 

1 engine runs most electrical and hydraulicsystems causing  Power loss

even mordern planes still have this .

 

In game

The 111 n 88 the Right engines use 5-25L/hour more fuel then the right depending on settings

2400 RPM 1.3ATA (Left 430L/Hour Right 455L/hour) at correct alt

 

 

Mmmmh, so most systems are linked onto the right engine is that correct ?

I'll have a look in my books to double check that. Thanks for your input Shadow. 

[OrLoK]

 

 

Mmmmh, so most systems are linked onto the right engine is that correct ?

I'll have a look in my books to double check that. Thanks for your input Shadow. 

 

I now know my new target!

[=TBAS=Sshadow14]

they might be.

most planes its on engine or the other.
not saying that exact cause of it ingame or the 111 is like that but fuel flows and plane behavior would suggest it is so .
 

[Guest deleted@50488]

Well, 

 

I installed il2 ( again ) and tested the 111 for a while, but strangely I never noticed any right rolling tendency, unless when I cut power in a shallow dive...

 

But I did pay attention to some of the details mentioned above, that show that it's implementation is probably filled with many other good examples of attention to detail - I did notice the difference in FF between the left and right engines - nice detail !

[=TBAS=Sshadow14]

Yeah heres a pic for reference before someone on here says im lying.
Forgot we need them here like in court of law.

[56RAF_Roblex]

 

 

the video is showing what I'm expecting the plane to do : propwash + pushing the tail from the left side, so with the combination of the propeller torque, the nose will have a clear tendency to swing to the left requiring right rudder input to compensate

 

Did you get confused?  If the tail is being pushed left then the nose will swing *right* requiring *left* rudder.

[TG-55Panthercules]

Did you get confused?  If the tail is being pushed left then the nose will swing *right* requiring *left* rudder.

 

He didn't say that the tail was being pushed left - he said it was being pushed from the left (i.e., being pushed to the right).

[F/JG300_Gruber]

He didn't say that the tail was being pushed left - he said it was being pushed from the left (i.e., being pushed to the right).

 

Thanks, you understood me right 

 

 

Yeah heres a pic for reference before someone on here says im lying.

Forgot we need them here like in court of law.

 

Hmmm, so which one is driving most of the power hungry goodies ? The one which runs hotter or the one eating up more fuel ?

[=TBAS=Sshadow14]

the one using more fuel

Its cooler as higher engine and fuel flow at same alt keeps it a little cooler.


Than again it could all just be a game bug thats randomly acts like real plane engines

[F/JG300_Gruber]

OK.

 

So back to the start mark it seems. If most systems are linked to engine n°1, again the higher thrust of the n°2 should make the aircraft yaw left... Still no reason to yaw right like a Peshka.

What surprises me is that if this is a modelling error, it has been transfered to the H16 as well without being noticed. 

 

I thinking about writing a PM to the engineering team about this.

[Guest deleted@50488]

OK.

 

So back to the start mark it seems. If most systems are linked to engine n°1, again the higher thrust of the n°2 should make the aircraft yaw left... Still no reason to yaw right like a Peshka.

What surprises me is that if this is a modelling error, it has been transfered to the H16 as well without being noticed. 

 

I thinking about writing a PM to the engineering team about this.

 

 

 

​​You're right and my tests were not correct :-/   Indeed there's a right rolling / yawing tendency !  Reminds me of the new "bug" in X-Plane 11.10, with the recently introduced new propwash calculations...

 

I also noticed that one the aircraft is loaded in Quick Mission it comes with a "-1" setting for Rudder Trim ( portside ! ) maybe to compensate for this "weird" right rolling yawing  tendency. Apparently Aileron trim is initialized null.

 

Thx!

Edited December 13, 2017 by jcomm

[AnPetrovich]

F/JG300_Gruber,

I've received your PM and just have made a quick test flight on H6 (default payload, 100% fuel, ISA).

I do not see any noticeable yaw reaction on throttle. The side splip ball indicator is always in the center position, and the airplane's heading doesn't change.

As it should be, because the propwash does not affect the tail on this airplane in the level flight.

The only thing that affect the yaw, as I see, is a gyroscopic moment due changing the pitch when you operate the throttle.

Could somebody make a video which demonstrates the problem you are talking about?

[Guest deleted@50488]

@AnPetrovich,

 

Strangely, i run the same test today, starting with 75% fuel, no ammunition, 1000m, and tried without success every possible combination of power setting just to find no right rolling tendency, except when, but that's correct, throttle is moved to iddle or very low settings ( the negative propwash and the prevalence of the aerodynamics compensations for cruise flight then cause na expected right rolling tendency as in pretty much every prop aircraft with CW rotating prop(s))

 

So, if in one of my previous posts I answered the original post saying that I was also able to replicate the "problem", truth is it is no longer true - everything appears to be ok now ( ? )

 

Just really don't understand what cause it in one of the tests I run before ...

[=TBAS=Sshadow14]

you guys have to remember the plane is not balanced or even in terms of drag and weight balance.

1 side is missing a fuel tank
1 side of the cockpit narrower
1 side of the plane has pilot control the other doesn't

Drag and weight are not even like the 88 well balanced

[Yogiflight]

 

 

1 side is missing a fuel tank

Sorry, but what missing fuel tank are you talking about? Both wings have an inner and an outer tank. You can see the switches of both gauges change between inner and outer tank.  The only fuel tank, that is missing, is the fuselage fuel tank, that is missing in the H16.

[=TBAS=Sshadow14]

ohh yeah sorry 1 tank missing in the H16 ...

Shh i just woke up

[Guest deleted@50488]

And... yesterday's test ( mine ) was in the H6, not in the H16 I had initially tried it in after the OP ...

 

Maybe the problem does indeed affect only the H16 variant ( ? )

[=TBAS=Sshadow14]

what rudder trim and speed are you cruising at ?

11 requires constant left rudder trim to stay ball centered and level..

Lmao i thought i was bad with worrying about numbers when i fly the 111.
but a little yaw never bothered me,
It was never a truly stable plane to fly and needed constant re-trimming.