Pilum

OK, I'm not sure how I should interpret this? Does it mean you are looking into the trim and flap moment issue? :) Is the measured Me109G data you are referring to above from the attached report? Also, in the current DCS Me109K4 where is the center of gravity located when fully armed and full internal fuel load?

Yes, but it would be interesting to know how much ballast they but in there and where the c.g ended up. So what we need is a so-called "Ladeplan" for the K4 showing weights and balance.

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?

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

I'm not sure but I think the reduced upward throw from 3.4 to 1.17 deg could be due to the later me109's being more nose heavy due to the heavier engine installations. IIRC then there was ballast in the tail in the K4? Regarding Mr. Brunotte statement, I think the DCS K4 is also controllable in a wide speed range so I see no problem there. In addition: My main concern is not the trim range (although it would of course be nice to be able to completely trim out at high speed if this is historically correct ;)) but the trim change due to flap deployment and that was why I posted in the first place.

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.....

So does this mean you have had some indications that this will be corrected then? Here is some more information further supporting that there should be a nose down trim change when deploying 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.”

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.”

Yes let's hope they do fix it. It looks at bit strange when you deploy flaps and trim and the outer wheel spins counter clockwize and the inner trim wheel clockwize. Doing that while flying IRL would require a great deal of finger dexterity. :music_whistling: Actually the British RAE conceded that the flap/trim arrangement with the control wheels placed together was one of the good points on the Me109 because you trimmed at the same time you deployed or raised the flaps by spinning both wheels in the same direction. Otherwize they were rather sparing in their praise of the Me109E as I recall it :smilewink:

Yep, either they tweaked this or I have made huge progress as a pilot. Unfortunately I don't think it's the latter :smilewink:

I have since I got the K4 of course been testing out it's characteristics and left the Dora in the hangar. To me it seemed easier to do takeoff's in the K4 because it seemed more responsive to rudder input and there also there seemed to be less lag than with the Dora. No need to tap the brakes at all. Then it struck me that we now have 1.2.12 and has this been tweaked in the Dora as well? Before 1.2.12 I used to have to use the brakes to keep straight but now the rudder is all I need and taking off is a breeze :) So is it just me or has this been adjusted? Anyone else notice any difference in Dora's response to rudder at takeoff?

Concerning the processing cost of player versus AI DM: While I of course don't know the inner workings of the DCS source code, I can see a way around this: Just introduce an breakpoint between AI and player DM in the code for offline play: If num AI>X use AI DM for AI else use player DM for AI Since there obviously already is a player DM the amount of coding needed should be minimal. Just a matter of deciding X which could even be a player defined variable so you could set this depending on your computer specs........

Yep, the AI are simply too tough in DCS right now but as I see it, since it seems pretty balanced it's not as serious as it would be if the relative performance say between 50-cals and Mk108 was off. IIRC then the German WW2 estimate was circa 4-5 Mk108 hits to down a B-17 as compared to 20 Mk151 hits. Not an absolute number of course but statistically....

With the caveat I have done no systematic tests with the K4, I get the impression that it in many cases it requires around 4-5 Mk108 hits to put P-51 AI out of action. This is too much I think since it seems that IRL in many cases just 1 Mk108 hit should be enough. However, on the positive side the tough AI seems to be a "balanced" problem right now since statistically you need around 100 50-cal hits to down an AI Dora and around 20 Mk151 hits to down a p-51. It also seems to be a general problem that AI performance is not affected by hits and they happily continue flying until they die irrespective if they soak up 20 mm or 50-cals. So it looks like you in DCS need around 4-5 times as many hits across the board meaning it is at least balanced even though I would be happy if the AI damage model was adjusted so that statistically you would need either one Mk108, 5 Mk151 or 20 50-cal hits to shoot down the AI which would bring it closer to IRL numbers. So IMHO, the Mk108 does no better nor any worse right now: It's just a general problem in DCS that the AI are too tough :smilewink:

There seems to be something strange with the trim change when flaps are deployed in the Me109K4: Trailing edge flaps should give a nose down pitching moment when deployed while in DCS there is a nose up pitching moment. The nose down pitching moment is due to the fact that the extra lift generated by the flap acts aft of the center of gravity which causes a nose down moment. This effect is to some extent offset by the increased downwash on the tail which however is not large enough to cancel out the nose down moment which consequently needs to be trimmed out. At least this is the case in most aircraft I believe. In fact IIRC then this was why the trim and flap wheels were placed so close together on the Me109’s: When deploying the flap the pilot would grab both wheels and move them togther which would deploy the flaps while at the same time moving the tail plane incidence to cancel out the trim change caused by the flaps. So IRL the pilot would spin both wheels counter clockwize when deploying flaps. However, in the DCS Me109K4 it is the other way around: The flap wheel is spun counter clockwize to deploy flaps while the trim wheel needs to be spun in the other direction to trim out the nose up moment caused by the flap deployment. This indicates to me that there is a fundamental issue here with the DCS Me109K4: How come we get a nose up moment and not a nose down moment when flaps are deployed?

Also want to add my thanks and appreciation for the work ED is doing. I really like the look of the new Me109K4 and of course the other WW2 birds. In addition I want to add that the posts I do listing things that seem off in bug section are by no means a critique but merely ruminations and suggestion for making a great sim even better. One more thing: That the developers take the time to interact with us forum members here is great and something other flight sim developers could learn from. Keep up the good work and thanks ED! :thumbup:

Well AFAIK the Me109 slats are a derivate of a design by the British company Handley-Page and the stated idea with this design is exactly the automation and that the flaps are deployed gradually which was also patented by the same company. However, slats of this type that are not properly set and aligned can come out with a bang: As an example, if there is a gap on the slats trailing edge this will cause a suction force that keeps the slat closed until the leading edge suction forces overcome this and the slat deploys instantaneously with a bang. This could very well explain the Russian results that they deployed with a bang at a higher Cl than expected. In addition, that they open and close at different speeds is not strange since the slats in the figure I referred to in post #1 also show this type of hysteresis. In addition, British RAE report RM2361 Me109 handling and performance evaluation, M B Morgan, states that the slats deployed at Cl=0.865 so this seems to be in line with the German numbers I posted before in post #1. So I’m more inclined to go with the German numbers and explanation for how the slats should move as mentioned in post #1: If well maintained and properly aligned and trimmed, they should deploy gradually and not just snap out. Anyway, would be great if you could get some info from former pilots on this.:thumbup:

OK,good! Do you have any info on if it's going to impact the AFM or is it eye candy only?

It looks like the slats just pop out and don’t move out gradually as they should IRL: The slats on the Me109 either had a linkage system (early model) and later a rail system with rollers. Both were designed so that the resulting aerodynamic forces on the slats would pull them out gradually. So if the aoa is gradually increased, the slats should move out only gradually starting at Cl=0.8 and aoa 12 degrees and then move out progressively as aoa increases to about 18 degrees (Cl=1.2) when they are out against the stops. Reference: Hoerner Fluid Dynamic Drag book page 6-9 figure 16 which in turn comes from German WW2 report by Petrikat, Slats in a water tunnel test, Ybk D Lufo 1940 p I-248. Consequently, it would from a visual perspective be nice if this was modeled in the sim, i.e. that if you gradually increase load factor, the slats move out gradually as well. However, one question that also springs to mind is how the slats are taken into account in the DCS AFM? If this has an impact on the flight model then the slat issue is more serious than a mere eye candy issue I think.

+1

I think you lost track of the fact that the onus is on you to come up with the evidence: Kennblatts were used by the Germans themselves to summarize the key characteristics for their aircraft so I'm more inclined to believe them and the attached Kennblatt rather than some cherrypicked top end outlier you found in a test report with unknown provenance.

Blanket statements claiming some data to be the "correct data" and the other data as "significantly simplified need to be backed up by evidence. AFAIK German Kennblatt figures are reliable but if there is evidence to the contrary then I'm willing to change my mind. Also, on what evidence does the claim it is "understood" that the climb was done under certain conditions meaning they "can be improved significantly" rest? Anyway, It's up to DCS to judge if they rather trust the kennblatt figure of 580 Km/h or if they want to use your figure of 595 Km/h. I suppose they have both datasheets. Seeing you are advocating 595 Km/h Kurfurst, I'm sure there is no higher figure around for the K4 so it's always good to know what value the top outlier has. ;)

OK, thanks for that. Should have RTFM before posting :doh:

OK, that is interesting data but they are not the same engine really: The DB605A has a lower compression ratio and runs on B4 fuel while the DB605 AM has a higher compression ratio and runs on C3 fuel so thermodynamically they are different. That being said, it was interesting to see that there does not seem to be that much more power that needs to be cooled of when you compare these different engines and that if the radiator can handle the DB605A at 1310 Ps then it can of course most likely handle the 1800 Ps DB605AM. But is DCS not modelling the Me109K4 with the DB605D 1.8 ata engine? For this version we do at least have solid kennblatt data: 1800 Ps S&N Leistung and 1275 Ps S&K Leistung with S&N Leistung giving 710 Km/h at 7.5 Km and 580 Km/h at sea level with the standard propeller. There is of course other K4 data but some of that is with a special thin bladed propeller and I would assume that DCS would model a K4 with a standard propeller? Anyway, I guess we will see that on Wednesday.

Yep, some pilots complained that it required quite a bit of pressure IIRC which we of course won't suffer from in DCS ;) OTOH during a dogfight the speed keeps changing so you need to change the rudder pressure anyway to keep the ball centered for gunnery. Trim would have been helpful for cruise and climb though.......