[CLOSED]Bf-109 Trim controls

[Anatoli-Kagari9]

For me the only problem right now is the pitching moment due to flap deflection.

 

As Pilum noted in the "Bugs" section, and even according to the ED Manual, flaps in the K4 make the aircraft nose heavy, while the model presently transits into a tail heavy state...

[Ballenato]

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

 

 

 

 

 

Unfortunately not in my hands. A year ago my HD broke and lost all documentation relating to production test at Messerschmitt. Fortunately I know who has them and I can tell him send them back again, hope in a short time ill get them back. I'm still recovering and collecting the lost information, it was quite traumatic see years of research lost by failure of hardware. Sorry :(

 

 

 

PD: Thx Yo-Yo for the answer.

[DB 605]

I just got my hands again finnish book called "Lentäjän näkökulma" (pilot's viewpoint). There is quite well known finnish test report from 1943, of Bf 109 G2 "MT-215", Erla-built machine wich was in almost new condition. You can found some performance figures of this test from Kürfurst site for example.

 

This part of text is quite interesting and pretty much opposite of what we have currently in game (note that this is my own translation and may contain some errors but point should became clear. Original text by test pilot himself, Pekka Kokko. Landing gears are already down at this point): "Taking flaps down makes plane nose-heavy, so at same time must trim elevator to position -3...-5, wich is good position to landing."

 

Now if you trim plane in -5 position in landing configuration at game, it'll became pretty horrible to fly. You must push the stick forward to almost limit and if you let go, plane will dart up like a rocket and stall. I have some doubts about that would be case in real life...

 

 

Another interesting note comes from Mark Hanna's report of flying the "Black 2", ex-buchon converted to Bf 109 G10:

 

"Above 550km/h, one peculiarity is slight nose-down trim change as you accelerate. This means that when you run in for an airshow above 500km/h, the airplane has a slight tucking sensation- a sort of desire to get down to ground level. This is easily held on stick, or it can be trimmed out, but it is slightly surprising initially."

 

Now we get this in game only in when plane is trimmed full nose-heavy and speed doesent affect it a lot.

 

Yo-Yo, as you are far more knowledgeable about these things than me, would you explain what would be the benefits of design if trim really worked like it does now in game? I.e when trimmed full nose-heavy it will go only slightly nose-down and when trimmed full tail-heavy flying became almost impossible?

Edited December 10, 2014 by DB 605

[Pilum]

Good info DB 605 :thumbup:

 

And here is some more input from two other sources on the change of trim due to flaps:

 

British Royal Aircraft Establishment report RM2361 Me109E handling and performance evaluation, by M B Morgan, September 1940:

 

”The juxtaposition of the tailplane-adjusting wheel and the flap-control wheel was also considered an excellent feature, as the wheels may be operated together with one hand and the change of trim due to flaps thereby automatically corrected.”

 

The same report say’s that a total of 5,75 revolutions of the trim wheel were needed to move the tailplane from the max incidence of +3.4 degrees to –8.4 degrees. So it seems the Emil at least could increase the tailplane incidence as far as to 3.4 degrees positive.

 

From article ”Four of the finest” in Royal Air Force Yearbook 1975: English test pilot Captain Eric Brown on the captured Me109G6 he flew in 1944:

 

”The flaps were raised manually by means of the outer of two concentrically-mounted wheels to the pilot’s left, the inner wheel adjusting the tailplane incidence. Thus the wheels could be moved together to counteract the change in trim as the flaps came up.”

[SlipBall]

+3.5.. that would be nice

[Pilum]

+3.5.. that would be nice

 

Yup, but this was on the Me109E though and unfortunately the K4's Flugzeughandbuch gives max 1 deg 10 min so that's just 1.17 degrees. But if we now only have 1 deg in DCS then another 0.17 deg would at least be in the right direction :smilewink:

 

OTOH would be interesting with some c.g. data on the K4. If this was more nose heavy than the E then you would not need to set as much positive stabilizer to hold down the nose. IIRC then both later Spits and Me109's carried a lot of ballast in the tail to offset the heavier engine installations on later marks so maybe that is why they settled for less upward trim.....

[Ballenato]

Differences G1 Vs K4 elevator/trim deflection. The K4 is from somewhere/time Kurfust post. The G1/2 one is from original found at Ausgburg Messerschmitt factory.

[SlipBall]

Differences G1 Vs K4 elevator/trim deflection. The K4 is from somewhere/time Kurfust post. The G1/2 one is from original found at Ausgburg Messerschmitt factory.

 

 

cool!...but I can't make out the + num in the first image, I'll guess 2 ?...looks like 1 70

[Pilum]

Differences G1 Vs K4 elevator/trim deflection. The K4 is from somewhere/time Kurfust post. The G1/2 one is from original found at Ausgburg Messerschmitt factory.

 

Nice! Thanks for posting. So it looks like they progressively reduced the total throw of the stabilizer going from E to K4.......

[SlipBall]

it seems to me that some thing might have changed with her nose down capability, and in a positive way. I did however re-calibrate, so it could have been that, or could be that mini up-date I had today

[Yo-Yo]

Nice! Thanks for posting. So it looks like they progressively reduced the total throw of the stabilizer going from E to K4.......

 

Yes, and 1.83 degree (1 deg and 50') we have now is a little bit more...

 

Anyway, it's not so simple with the retrimming for flaps down. THe test flights results show that balance for neutral stability is different for flaps up and down conditions. It means (if its familiar to you) that balance curves in CL-Elevator_position coordinates can lay in different ways regarding CoG position, i.e. retrimming for the same CL can be in both direction or zero depending on CoG position.

[Pilum]

Yes, and 1.83 degree (1 deg and 50') we have now is a little bit more...

 

Anyway, it's not so simple with the retrimming for flaps down. THe test flights results show that balance for neutral stability is different for flaps up and down conditions. It means (if its familiar to you) that balance curves in CL-Elevator_position coordinates can lay in different ways regarding CoG position, i.e. retrimming for the same CL can be in both direction or zero depending on CoG position.

 

Yes, I'm aware that the c.g. position influences trim but I think what would be good would be to get the DCS K4 trim behaviour when flaps are deployed similar to that in the quotes I posted irrespective of the reason.

 

I'm not ruling out that the issue is c.g related although I would have guessed it had more to do with the aerodynamic modeling but the DCS AFM is your domain so I was hoping you would tell us why there seems seems to be a discrepancy here? From your earlier replies and the previous discussion on the K4 weight & balance it sounds like you suspect the discrepancy is related to c.g issues?

 

In addition, if we have +1.83 deg in DCS and it should be +1.17 IRL and it is still difficult to get neutral trim at high speed then maybe this also indicates that the DCS K4 is too tail heavy now?

Edited December 10, 2014 by Pilum

[Anatoli-Kagari9]

Yo-Yo,

 

I agree it's a complex matter indeed, and for instance depending on various factors the flap deployment acn indeed create a pitch down moment, while on other occasions the pitch can increase, but on both situiations it looks plausibkle to me, so, probably you got it right after all...

 

Thx

[Fox One]

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.

 

I think that should pretty much apply to K model too. I’m no 109 expert, but I would imagine from G to K they didn’t change the center of gravity position with like half a meter. Probably such a huge change would be required in order for the K to differ so much from those trim settings recommended for G-6.

 

I’ve flown it up to 11,000 m without stores and with one 500 Kg bomb. Dived to speeds close to 900. Trimmed it for landing approach with little fuel or full tanks. And I never needed more that -1 pitch trim. If everything in DCS regarding trim is as it should be, then why the trim range goes up to -6? What is that good for?

 

Anyone have real K4 manual? What are recommended trim setting there for T/O and landing?

 

Unfortunately it seems like even luftfahrt-archiv-hafner.de doesn't have K pilot notes.

[Friedrich-4B]

These are from the 109 K Handbuch, November 1944 Teil 4 showing how the control linkages were set:

 

 

 

Edited December 11, 2014 by Friedrich-4/B

[Kurfürst]

I wonder if the DCSK4's CoG misses the weight of the MW-50/Fuel system alltogether, because the flying weight of the aircraft shown in the mission planner is missing the weight of that MW-tank (32 kg) and its contents (~85 kg)... though that would make the thing even more tail heavy.

[DB 605]

 

If everything in DCS regarding trim is as it should be, then why the trim range goes up to -6? What is that good for?

 

I asked that from Yo-Yo in post #28, hopefully he will answer...

Unfortunately it seems like even luftfahrt-archiv-hafner.de doesn't have K pilot notes.

 

I see, sad to hear. Would have been very interesting read.

[Ballenato]

For sure i may be mistaken, don't know your first resources for K4 develop, but did you take into account real pilots of real 109? I mean pilots that flew restored 109 nowadays. Very first hand source IMHO.

 

Greets

[IvanK]

I find that I run out of Stab trim at around 430Kmh IAS with MW50 in the tank, and around 520Kmh without MW50 (i.e. jettison it). Anywhere above these speeds with full down stab trim I need to hold a push force to hold the nose where I want it.... feels to me that I am running out of Nose down stab trim.

[Anatoli-Kagari9]

IvanK,

 

I am trying to find that text, but I did read somewhere on RW pilot notes that this was indeed the case with the K4.

[Solty]

I find that I run out of Stab trim at around 430Kmh IAS with MW50 in the tank, and around 520Kmh without MW50 (i.e. jettison it). Anywhere above these speeds with full down stab trim I need to hold a push force to hold the nose where I want it.... feels to me that I am running out of Nose down stab trim.

 

You can't jettison the MW 50 tank:huh:

 

Also at above 500kph you should have stiff elevator so it wouldn't probably have the upward motion. But control would be much harder too

Edited January 22, 2015 by Solty

[IvanK]

You can't jettison the MW 50 tank:huh:

 

Also at above 500kph you should have stiff elevator so it wouldn't probably have the upward motion. But control would be much harder too

 

No I meant the MW50 tanks contents :) .... pulling the jettison/dump control in the lower right corner of the cockpit.

 

Ref stiffer controls ... yes I understand that , but I am referring to stick free trimmed state to hold 1G flight, not stick force per see. I find it unusual that I cannot trim to zero stick force at typical operational speeds. however if that was the historical case so be it ... it just strikes me as unusual.

Edited January 22, 2015 by IvanK

[Yo-Yo]

I think it was Messerschmitt's style of design. Even G2 was out of trim with full tank and trimmer full nose-heavy as it is documented in NII WWS report.

 

Anyway, we asked Erich about trimmer setting and he told that he trimmed the plane only once for cruise and then did not touch the wheel.

[SlipBall]

I usually don't touch the trim much as-well, even for my landings I do not bother to

[Yo-Yo]

I guess the problem (if it presents) is in the joysticks with hard center force like Thrustmaster... never like it especially for formation flying.

 

MSFF2 - our choice! :) Get the hand away and no trimmers required :)