[CLOSED]Bf-109 Trim controls

[Pilum]

I have to add that pilot's notes on modern flying 109s must be added with actual balance for the trim they use and whether trim tabs were bend for their planes to get said trim.

 

Though NII VVS report has no direct mentioned neutral trim tab, the common engineering sense tells that as the trim tab is ADDITIONAL and secondary mean of trim, so, presumed neutral.

 

I agree that it makes sense that the NII VVS test most likely had the trim tab in a neutral position if nothing about the tabs was mentioned in the report. In addition, I have no reason to think otherwize than that the current DCS Me109K4 is correctly modeled when it comes to cg, response to elevator and trim changes etc so don't get me wrong, I'm not critizicing, I'm making a suggestion for a refinement :smilewink:

 

The point I want to make is that the trim tab on the trailing edge of an elevator is a powerful tool to change the trim and that small adjustments of the tab will give significant changes in the trim point. In addition, I see no contradiction either to the NII VVS test, restored 109's flying today or the current model of the K4 if the elevator trim tab in DCS was to be digitally tweaked slightly. In fact, I just took the DCS K4 for a ride and concluded that it is very close to being fully trimmed at high speed with the adjustable tailplane only and looking at the external, the change of elevator angle required to trim is barely noticeable.

 

So, seeing the very small change of elevator needed to trim, I think tweaking this in the DCS model would be the correct thing to do since IMHO an IRL 109 pilot would no doubt ask his crew chief to do this.

[IIIJG52_Otto_]

I agree with Pilum and Crumpp. The trim tabs are a final touch, so that the airplane fly, to pilot' taste..

[Anatoli-Kagari9]

And... the aileron trim too, please, like we can ( could ? ) in the Fw190 D9 ;-)

 

And... the rudder trim tab too - why not ?

[Solty]

I think that 109 should be possible to trim in the rearm menu on the ground. That would be accessible and easy to change. For MP that is. Second option could be in ME, for SP purposes.

[Yo-Yo]

What's the point to double the trim sources for pitch? I would understand if it is constant value. But the pitch trim is something you have to set directly before you start to roll regarding the current balance, field, wind and finally - your preferences, etc.

[Anatoli-Kagari9]

What's the point to double the trim sources for pitch? I would understand if it is constant value. But the pitch trim is something you have to set directly before you start to roll regarding the current balance, field, wind and finally - your preferences, etc.

 

I agree regarding the pitch trim, because indeed the aircraft models no rigging variations with time, hardware stress etc... So, our simulated Bf109 K4 will always be in as good shape as when it left the factory properly calibrated, unless it takes hit's... but that's another story...

 

But! Aileron and Yaw adjustable trim tabs ( by ground crew ) could be given the chance to be adapted to the type of flight we're up to, just like in the Fw190D9 ;-)

[Yo-Yo]

I agree regarding the pitch trim, because indeed the aircraft models no rigging variations with time, hardware stress etc... So, our simulated Bf109 K4 will always be in as good shape as when it left the factory properly calibrated, unless it takes hit's... but that's another story...

 

But! Aileron and Yaw adjustable trim tabs ( by ground crew ) could be given the chance to be adapted to the type of flight we're up to, just like in the Fw190D9 ;-)

 

They are already available.

Edited March 6, 2015 by Yo-Yo

[Anatoli-Kagari9]

They already available.

 

Ok, thx Yo-Yo...

 

Last time I tried it didn't have any effect on the K4 ( aileron trim ). Maybe it got active only in 1.2.15 ( ? )

[Yo-Yo]

Possible versions lag.

[IIIJG52_Otto_]

In the book: "Messerschmitt Bf-109; Owners' Workshop Manual" of Haynes Publishing 2009.

There is some commentaries about trim settings of Bf-109 in operations and Bf-109G2 "Black-6", the last original "Made in Germany" werk nummber: 10639, restored to airworthy condition.

 

In that book, Dave Southwood the RAF test pitot, who flew the Bf-109G2 "Black-6", He says.

In page 96:

"" In the pre -take-off check, I set 20º flaps and 1º nose up tailplane trim. The original data said 0º trim, but 1º nose up was added after the propeller ground strike on the first sortie. ""

In the page 97 of same book Dave Southwood says:

""trim settings: The ailerons and rudder fixed trim tabs were adjusted to give centralized slip ball and wings level flight with cruise power (1.0ATA, 2000rpm) set in straight and level flight. If adjustments were needed, the rudder trim had to be adjusted first before the required aileron trim tab adjustments could be made. Note that if the ailerons trim was correct at these cruise conditions, it was correct throughout almost the entire required flight envelope. ""

 

This means the airplane is not tail heavy, and capable to straight and level flight with correct trim tabs set on ground, and with elevator trim handwheel set to zero.

 

What's the point to double the trim sources for pitch? I would understand if it is constant value. But the pitch trim is something you have to set directly before you start to roll regarding the current balance, field, wind and finally - your preferences, etc.

I quote myself, to remember what the pilots who are flying these airplanes are reporting...

I don't want the Bf-109K4 become a UFO, I just want to behave like the real airplane IRL

And now 109K4 in DCS is far from that behavior, it was stable with a tendency nose-heavy that pilots was reporting.

 

Väinö Pokela, Finnish fighter ace (5 victories) and Me 109 trainer about Me-109G, he say:

""It flew like on rails even when shooting."""

 

With de CoG, displaced rearward the bf-109 have not the reported stability by the pilots.

I remind you also, that we are now taking-off with the handwheel trim set to +1, (nose-down) and that is just the opposite of that pilots was done in reality.

The strong tendency nose-down with landing flaps deployed, which force to adjust the trim handwheel full nose-up, is not modeled now in DCS.

This makes me think that trim data in the VVS test, that Yo-Yo says are miscoded or inverted.

Edited March 6, 2015 by III/JG52_Otto_+

[Yo-Yo]

I quote myself, to remember what the pilots who are flying these airplanes are reporting...

I don't want the Bf-109K4 become a UFO, I just want to behave like the real airplane IRL

And now 109K4 in DCS is far from that behavior, it was stable with a tendency nose-heavy that pilots was reporting.

 

Väinö Pokela, Finnish fighter ace (5 victories) and Me 109 trainer about Me-109G, he say:

""It flew like on rails even when shooting."""

 

With de CoG, displaced rearward the bf-109 have not the reported stability by the pilots.

I remind you also, that we are now taking-off with the handwheel trim set to +1, (nose-down) and that is just the opposite of that pilots was done in reality.

 

What is the exact value of CoG distant from the Neutral Point - 2.7%, 3.8%, 0.7% to match "like on rails" definitions?

Does it mean that nobody of MkV Spit pilot can shoot accurately as Mk V was neutral even in gliding?

 

As well as I-16 pilots.

 

By the way, most of powerful fighters were prone to be neutral or even unstable at power-on conditions due to prop effects.

[Crumpp]

Does it mean that nobody of MkV Spit pilot can shoot accurately as Mk V was neutral even in gliding?

 

It means they are going to have a harder time shooting accurately compared to a more stable airplane.

 

That does not mean it is impossible but it will be different from a more stable design and it will take some time to get used too.

 

 

 

With its Neutral Stick Fixed and Stick Free neutral to unstable at normal CG, short stick travel, sensitive elevator, and deep high energy buffet zone, the Spitfire is going to be a fun airplane to master but it was a pilot's airplane.

[Anatoli-Kagari9]

Excellent source of info Crumpp.

 

We should save this link, so that when Yo-Yo becomes attacked by all of the naysayers, because they feel the Spitfire is impossible to properly handle, we can then remind them of these notes!

Edited March 6, 2015 by jcomm

[Crumpp]

, so that when Yo-Yo becomes attacked by all of the naysayers,

 

I will understand his pain.....

 

:noexpression:

 

they feel the Spitfire is impossible to properly handle, we can then remind them of these notes!

 

Because there will be those people.....

 

:thumbup:

[Pilum]

I hope no one falls for the OFF TOPIC Spitfire trolling posted above. Seriously, if you feel an urge to diss the Spit even before it is released then by all means start a dedicated whining thread on that but pls don't mess up this thread where the topic is the 109's trim controls. Thank you.

[Pilum]

What's the point to double the trim sources for pitch? I would understand if it is constant value. But the pitch trim is something you have to set directly before you start to roll regarding the current balance, field, wind and finally - your preferences, etc.

 

Sure, we don't need to introduce a secondary source for trim in pitch: However, what a change in the elevator trim tab setting would accomplish is a translation of the trim range of the adjustable tailplane to encompass a larger nose down range meaning you could actually trim out the K4 also for high speeds. How large this translation should be would be determined by how much up bend you would apply to the trim tab and the point here was that if this was configurable in DCS (prior to take off) then we could all set this to our own individual taste just as it would be nice to do this also for rudder and aileron. Again, all this would be historically correct since this is what you IRL can do as well: The tabs allow you to within reasonable limits set at which speed and power setting your plane trims out in yaw, roll and pitch.

 

However, if having all this configurable in DCS is off the table then just adding a constant value to offset the current K4 adjustable tailplane trim range in pitch towards a more nose heavy range that would also be OK IMHO.

Edited March 6, 2015 by Pilum

[NineLine]

I hope no one falls for the OFF TOPIC Spitfire trolling posted above. Seriously, if you feel an urge to diss the Spit even before it is released then by all means start a dedicated whining thread on that but pls don't mess up this thread where the topic is the 109's trim controls. Thank you.

 

Well Yo-Yo mentioned the Spitfire first, and I dont see anyone dissing the Spitfire assuming you mean Crumpp's post?

 

At any rate, the topic is 109 controls, I do believe Yo-Yo's comments were not an invitation to start talking about the Spitfire...

[Pilum]

Well Yo-Yo mentioned the Spitfire first, and I dont see anyone dissing the Spitfire assuming you mean Crumpp's post?

 

OK, maybe painting up hypothetical scenarios with "naysayers" and "those people" in reference to the Spitfire is better classified as being made in poor taste rather than dissing.

 

At any rate, the topic is 109 controls, I do believe Yo-Yo's comments were not an invitation to start talking about the Spitfire...

 

Sounds good!

[Anatoli-Kagari9]

OK, maybe painting up hypothetical scenarios with "naysayers" and "those people" in reference to the Spitfire is better classified as being made in poor taste rather than dissing.

 

 

 

Sounds good!

 

Ah! So it was all about me :-)

 

Sorry to know :-/

 

No Pun was intended for anyone in special - I just recalled that sometime ago Yo-Yo had commented that if people were finding the pitch axis in the Fw190, and latter the Bf109 too sensitive, they would be surprised with the Spitfire handling, requiring even more careful touch... As far as I can tell from that text Crumpp posted, this is how the real thing was, which is great to know.

 

Just that.

[Crumpp]

I do believe Yo-Yo's comments were not an invitation to start talking about the Spitfire...

 

No it was not nor was there any intention of starting another Spitfire thread. I am sure there will be plenty in the future!

 

It was actually a comment on neutral to unstable designs. That is the topic Yo-Yo was referring too and was just using the Spitfire and I-16 as an example.

 

It really has nothing to do with discussing the Spitfire except is a good example of how instability effects the aircraft as a fighter. Neutral or unstable is not a requirement for good maneuverability either.

 

 

Neutral to unstable designs do not make good shooting platforms because of their stability characteristics. They tend to be "twitchy" airplanes and difficult to precisely control.

 

Which brings us back to the topic, the Bf-109 was good stable gun platform. Having to fight a fixed trim tab that is out of trim is not really representative of that gun platform. The fixed trim tab should not left at neutral but rather should be adjusted to the cruise position at Höchstzul. Dauerleistung. That is setting in the Flugzeug Handbuch, IIRC.

[Solty]

It's the fact that Spitfire (especially early versions) had realy big problem with high speed roll rate (similarly to the 109 the ailerons became heavy) but the elevator was light.

 

This created a situation at high speed when the pilot had to struggle and use a lot of force to move the ailerons and at the same time use the elevator very gently.

[Yo-Yo]

Sure, we don't need to introduce a secondary source for trim in pitch: However, what a change in the elevator trim tab setting would accomplish is a translation of the trim range of the adjustable tailplane to encompass a larger nose down range meaning you could actually trim out the K4 also for high speeds. How large this translation should be would be determined by how much up bend you would apply to the trim tab and the point here was that if this was configurable in DCS (prior to take off) then we could all set this to our own individual taste just as it would be nice to do this also for rudder and aileron. Again, all this would be historically correct since this is what you IRL can do as well: The tabs allow you to within reasonable limits set at which speed and power setting your plane trims out in yaw, roll and pitch.

 

However, if having all this configurable in DCS is off the table then just adding a constant value to offset the current K4 adjustable tailplane trim range in pitch towards a more nose heavy range that would also be OK IMHO.

 

Pitch trim ALREADY has a control in the cockpit. This trim covers full range of steady flight speeds and allows to trim nose-up attitude even if the plane has only a half of its elevator. And both trim tabs for a rudder and ailerons. I think it's not necessary to double pitch trim controls for the sake of "historical" setting of stab angle. Sic!

Edited March 7, 2015 by Yo-Yo

[SlipBall]

Personally I never touch or feel the need to adjust the trim, its good that it is there though. Same with the tail wheel lock, not really needed but good that it is available.

[Pilum]

Pitch trim ALREADY has a control in the cockpit. This trim covers full range of steady flight speeds and allows to trim nose-up attitude even if the plane has only a half of its elevator. And both trim tabs for a rudder and ailerons. I think it's not necessary to double pitch trim controls for the sake of "historical" setting of stab angle. Sic!

 

But the trouble right now in DCS is that the trim range does NOT cover the whole speed range: At top speed you need to apply a bit of down elevator to stay level. If you let go of the stick the K4 climbs. Again, if you don't want to add a trim tab option for the elevator then how about adding a constant to the elevator hinge moment to offset the adjustable tailplane trim range to a more nose heavy range? Again, this would be "historically" correct since any pilot could do this. Why on earth would a pilot fly around in an airplane that you could not trim to level flight at high speed when all he needed to do was get the trim tab on the elevator slightly adjusted?

[Solty]

The horisontal stablisizer trim is different than the trim tabs. It was used if the plane was too stiff or when the nose started to rise again.

"These were fixed trim tabs and not movable by the pilot. They were bent by the ground crews at the first flights. So the Me109 was pre-trimmed for cruising speed."

http://www.wwiiaircraftperformance.org/me109/Diving_Test_109F_W.Nr.9228_ger_eng.pdf

 

YoYo if you realy don't want it to be changed by the players (for some reason) just set those trim tabs to cruise speed, because right now the 109 pilots need to trim down -2 all the way just to keep it level through most of the flight. Because of that, the plane can't trimed to nose down attitude.

 

Also, why would the pilot need -2 and 6+ horisontal stab trim if anything above 0 makes the plane loop on itself :P

 

Another change that I would make is that both horisontal stabilizer trim wheel and flaps wheel should operate a little bit slower to simulate the realy small cockpit in which the pilot could operate.

 

NOTE: The trim wheel is even closer to the pilot's body so it would make it harder to move it well with that motion.

 

Just my few cents.:pilotfly: