[CLOSED]Bf-109 Trim controls

[NeilWillis]

According to the manual, the trim is adjustable from -6 to +1.something degrees.

 

I understand a negative number to mean the elevator would be angled downwards by the said -6 degrees, and the positive means up for the +1.something degrees.

 

If that is the case, isn't the trim reversed? On takeoff, rolling in full down trim gives a reading of 2 on the trim gauge, and full up trim give a reading of -6.

 

The controls aren't reversed, but it seems to me that the trim works the opposite way to that intended. Is this a bug, or am I just reading it incorrectly, and there is more up trim than down, and a negative number means up trim is applied?

 

This would easily account for the fact that we can't seem to get sufficient down trim under most flight parameters.

[Anatoli-Kagari9]

It was developed that way, next to the flaps wheel, because it was more intuitive, and supposedly easier to cope with by the pilot.

 

Reasoning is, if you add flaps, you will operate the trim wheel in the same direction. The effect of deploying flaps should actually be that of the "nose becoming heavy", calling for trim "up", and hence rotating the trim wheel CCW in the same direction that you operate the flaps wheel.

 

The reverse when you raise flaps, rotating it's wheel CW, and thus asking for trim adjustment CW...

Edited December 9, 2014 by jcomm

[NeilWillis]

Yep, I am not in any way questioning the operation, but I am questioning how much trim is available. And should negative trim = nose up? If the trim movement is back to front, and the -6 should apply to nose down, it might account for the difficulties.

Edited December 9, 2014 by NeilWillis

[Anatoli-Kagari9]

Yep, I am not in any way questioning the operation, but I am questioning how much trim is available. And should negative trim = nose up? If the trim movement is back to front, and the -6 should apply to nose down, it might account for the difficulties.

 

I guess the negative values mean nose up, positive nose down.

 

My only "experience" :) comes from using the Bf109 F4 and G2 in il2 BOS and the Bfs in Cliffs of Dover.

 

In il2-bos, the G2, just like the K4, also has between -6 and +2 for trim settings, but it doesn't want to rise is nose on takeoff like our K4 does :)

 

But! I believe Yo-Yo already stated that this is correctly modeled in the K4.

 

Probably teh only problem right now is that flaps set at 1 or 2 create a pitch up, instead of a pitch down tendency, which helps making things worse....

[Skulleader]

Hello guys,

 

If it's possible I would like to know if anybody can explain why -6 degrees ?

I don't know for you but for me during takeoff my trim is +2 and also all my flight + landing trim is +2.

 

But I don't know why -6 degrees, it's not too much -6 degrees ?

Naturally without the +2 degrees the K4 have heavy nose so added more negative trim it's very dangerous or for other reason ?

 

Use the negative trim is with external load ?

Please can you tell me when you use the negative trim ?

 

Thanks in advance, Skull.

[Anatoli-Kagari9]

I don't really know if the scale actually translates into degrees, but, anyway it proves that overall this aircraft might behave like being "nose heavy".

 

Also heard that during highspeed dives the pilots might get out of stick to recover, and had to use the stabilator.

 

Also, since it is supposed to carry up to 500kg bomb, which, I guess, might cause it even more nose heavy ( ? )

[FoReIgNeR]

In aerospace engineering a positive elevator (and elev. trim) deflection induces a negative pitch moment on the aircraft (i.e., nose down). The sign of the trim wheel corresponds with what I would expect.

 

However, I don't understand why the engineers didn't provide more nose down trim authority... But anecdotal evidence seems to indicate that 109 pilots indeed needed to push the stick a lot.

[Anatoli-Kagari9]

However, I don't understand why the engineers didn't provide more nose down trim authority... But anecdotal evidence seems to indicate that 109 pilots indeed needed to push the stick a lot.

 

Yes :) , and add to it the need for continuous left rudder at cruise and higher speeds or during dives, which "created the mith" that Bf109 pilots were chosen among those with a longer left leg :)

 

What the heck made them leaving the adjustable trims for rudder and aileron out of the cockpit??? Well...

 

But now that I finally started learning and using "Rise of Flight", I noticed that almost all of the models I tried, which do not have an adjustable stabilizer ( some ww1 models have it though ) I have to use forward stick at cruise settings :-/ Becomes tiresome during long missions ....

 

BTW: The -6 .. +2 range is common to il-2 BOS G2

Edited December 9, 2014 by jcomm

[El Hadji]

What the heck made them leaving the adjustable trims for rudder and aileron out of the cockpit???

 

I have often thought about this. And about the poor visibility. I mean German engineers always seem to come up with great solutions but I really can't understand why they failed here? Or is it just 'flawed' when we sit here 70 years later in front of our screens pretending to be aces?:joystick:

[DB 605]

And about the poor visibility. I mean German engineers always seem to come up with great solutions but I really can't understand why they failed here? Or is it just 'flawed' when we sit here 70 years later in front of our screens pretending to be aces?:joystick:

 

Look at fighters from late 30's, none of then actually have very good visibility. Or even early-mid 1940's...looks first generation Mustang, Corsair, P-47, P-40 etc. etc. All have horrible "bird-cage" canopies with endless rows of frames around. FW 190 was actually one of the first "next generation" fighters with cockpit kinda built on top of the frame rather than inside of it. So it's simply about evolution.

 

About elevator trimming issues, i think it's all about beta and there will be changes in future.

[Yo-Yo]

Look at fighters from late 30's, none of then actually have very good visibility. Or even early-mid 1940's...looks first generation Mustang, Corsair, P-47, P-40 etc. etc. All have horrible "bird-cage" canopies with endless rows of frames around. FW 190 was actually one of the first "next generation" fighters with cockpit kinda built on top of the frame rather than inside of it. So it's simply about evolution.

 

About elevator trimming issues, i think it's all about beta and there will be changes in future.

 

No, trim is the same real plane had and nothing will be changed in general. THe trim with 1.5 stab trim requires almost constant slight stick pulling at high speed. Especially with the full tank.

[SlipBall]

good to hear that it is correct, and no need throwing away what we have learned through practice already... I don't want to have it other than how it was in RL

Edited December 9, 2014 by GT 5.0

[DB 605]

No, trim is the same real plane had and nothing will be changed in general. THe trim with 1.5 stab trim requires almost constant slight stick pulling at high speed. Especially with the full tank.

 

Ok, thanks. Then something else will change i guess, as currently we need to trim it to nose-heavy even with full flaps and gears down. Wich is not exactly what i read from pilot notes or manual of real plane.

[SlipBall]

Actually she'll take off quite well with the trim set at 0 and even when set at -2 ...so I'm not sure if we really even have a problem :D

[Kwiatek]

Loking at DCS K-4 take off it's clearly got strong pitch up tendency during lift a plane which need s push stick reaction.

 

I dunno about it casue at video with real 109 G-4 Red 7 i see that pilot use strong push stick forward to rise the heavy tail then he move stick back to lift the plane.

[SlipBall]

I think what is being seen is low and slow, with lots of lift

[DB 605]

Actually she'll take off quite well with the trim set at 0 and even when set at -2 ...so I'm not sure if we really even have a problem :D

 

Well i only have G6 (real) manual, but there it says for take-off set trim to 1 (nose-heavy) and for landing -3 (tail heavy). In DCS if you trim it to -3 with full flaps and gears down, you have to push stick quite strongly to forward and if you let stick go it'll stalls right away. Feels quite unnatural to me and opposite to what i've read. Anyone have real K4 manual? What are recommended trim setting there for T/O and landing?

[pingo]

Well i only have G6 (real) manual, but there it says for take-off set trim to 1 (nose-heavy) and for landing -3 (tail heavy). In DCS if you trim it to -3 with full flaps and gears down, you have to push stick quite strongly to forward and if you let stick go it'll stalls right away. Feels quite unnatural to me and opposite to what i've read. Anyone have real K4 manual? What are recommended trim setting there for T/O and landing?

 

Well check this site:

 

https://mega.co.nz/#F!KJ5X1CgQ!E5bpiw4KSd8jCy3SZ9RS7Q

 

There are a few for the k4 think you would find the bf109k4_handbuck.pdf interesting it`s 26.8MB

[Kurfürst]

I have often thought about this. And about the poor visibility. I mean German engineers always seem to come up with great solutions but I really can't understand why they failed here? Or is it just 'flawed' when we sit here 70 years later in front of our screens pretending to be aces?:joystick:

 

Remember they never flew alone, like many sim pilots do... the loose Schwarm formation (aka tactics) made up for this - the whole formation could check the airspace with restriction, and they had radios to report contacts.

[Yo-Yo]

Well i only have G6 (real) manual, but there it says for take-off set trim to 1 (nose-heavy) and for landing -3 (tail heavy). In DCS if you trim it to -3 with full flaps and gears down, you have to push stick quite strongly to forward and if you let stick go it'll stalls right away. Feels quite unnatural to me and opposite to what i've read. Anyone have real K4 manual? What are recommended trim setting there for T/O and landing?

 

I do not use the manual just a Soviet report about 109G trim with all CoG positions, recorded elevator angle, etc, etc, for different stab position. I think it's more than enough to judge about the trim of the plane. Then we have special 109K weight and balance chart.

[Ballenato]

Yo-yo why not use original factory test? AFAIK, on K4 CoG changed due relocating internal system.

 

Greets

[Solty]

Check the section called "Landing" maybe that can help.

http://www.eaf51.org/newweb/Documenti/Storia/Flying_%20109_ENG.pdf

[Kwiatek]

I read about take off and with flaps 20 deg and trim +1 after rise the tail there was need stick back to lift the whole plane. In landigs section there is no info about trim. I think i got some book where Mark Hanna describe trim with landing on 109.

 

Dunno how it is with DCS K-4 casue i dont have it yet.

Edited December 9, 2014 by Kwiatek

[Kurfürst]

Yo-yo why not use original factory test? AFAIK, on K4 CoG changed due relocating internal system.

 

Greets

 

Do you have any K-4 Ladeplan perhaps? Or even better, the one which details every single item?

[Yo-Yo]

Yo-yo why not use original factory test? AFAIK, on K4 CoG changed due relocating internal system.

 

Greets

 

The test is conducted with regards of measured CoG location that gives certain %% of CG location regarding MAC. K4 weight and balance is taken from original factory documents, so, any test conducted with the same airframe with different weight and balance conditions will be valid.