Tail Coming up at ~70 km/h on Takeoff

I am reading many accounts and watching videos of restored Bf-109s during takeoff. A very common notation is that one should delay allowing the tail to rise before rudder becomes effective (60-70 km/h) and that it easily rises at this point.

But in DCS module I cannot get such tail rising behavior during the takeoff run. Even with full forward controls the tail is not rising smoothly, easily, or naturally until much faster (~140 km/h).

How can I raise the tail smoothly in this airplane to see over the nose at < 100 km/h?

Hi Frederf,

little kick on both brakes to get the tail up at around 70 Km/H. But if you hit the brakes to strong, you go nose over :).

On the other way i take off like in the 190, hold the stick till 120 Km/H back and than center it slowly, this make here going easy of the ground at about 160 Km/H, Now you need to pull the stick little bit forwart or you will stall. gear in, flaps in and down to ATA 1,25. I alsway take off with ATA 1,45 and 2600 rpm`s no MW50.

regards

Little_D

With flaps down to the 2nd mark the 109 comes up on the mainwheels quite nicely (not sure what speed but it is quite 'comfortable'. Just need to give it a bit more right rudder and maybe a touch of right aileron when the tail comes up. Will be a bit sudden with the left yaw but nothing too crazy.

dont know at what speeds exactly the 109 should pull up its tail...what i do notice though, is that all ww2 modules so far somehow dont want to pull their tails really up...watching videos on youtube of 109s, P-51s taking off, it seems they indeed get their butts sooner up, and then keep rolling on their main wheels for quite a while until they rotate.and it seems that the aircraft do that by themselves and no pushing of the stick is necessary...which goes hand in hand with many pilot comments where they say that pushing the stick was a bad idea, and the planes want to pull up their tails by themselves.

yes, in dcs, the tail comes up as well...but thats followed pretty much immediately with rotating off the aircraft...i think there's something slightly off in dcs. cant say what it is though, just my impression.

Nice videos!

Could it be that this has to do with how prop wash over control surfaces is modeled in DCS? I know someone will lose it at this comment but in the 'other' sim this effect is much more pronounced. Noticed in several videos with 109s in particular that they use alot of rudder when taxiing whereas in DCS its pretty useless. I always taxi 100% with brakes in the 109.

possible. look at how little right rudder the 109 actually needs there to stay straight on take off.

Yeah.. the rudder is utterly ineffective in DCS. Californischer riesenslip (sideslip)? No way. Snap roll? Not a chance. Taxiing with rudder, even at high RPM? Nope!

This always has thrown me off a bit tbh.

:lol::thumbup: yeah, californian sideslip...we already call it the lichtenstein slip

Prop wash impingement on tail surfaces could be the reason. In the video above it takes 24 seconds from brakes release to liftoff. The tail is definitely airborne after the first 10.

In this the transition is seen to take place at ~100 km/h indicated complete by ~130 km/h without extreme forward stick position.

You are comparing unladen, light aircraft with a fully armed module I think here.

As for the non-existent rudder inputs - just re-watch the video of the interview with Erich Brunotte the FW-190 pilot. He clearly states that full rudder - and some differential braking was required in the 109. The fact that you can't see any obvious rudder deflection in the videos may be down to the way the aircraft have been trimmed, or the low power settings used to take off, who knows?

The bottom line with all these discussions about flight models are purely opinion, and meaningless without any genuine supporting evidence. Why are you pinning something down to prop wash when there are far more factors involved, all of which contribute.

Have any of you tried taking off with less than, say, 30% fuel, and all the ammunition AND weapons stripped out? I suspect that the videos show aircraft far far lighter than the wartime configurations simulated here.

That would make an enormous difference.

there are enough wartime videos as well, which show the exact same behaviour. sure in war some took off with more than 30% fuel and fully equipped.. also, rewatch the video of erich brunotte yourself...lots of stuff which should make you doubt a couple of things in dcs, as for example the californian sideslip.

meaningless opinion?thats your opinion...

if you think dcs is 100% spot on to reality then fine for you,..there are people though who really like what dcs is doing, but are convinced that it could do even more realistic than it already does, and also think that we have the devs capable of improving the sim further.

meaningless opinion?thats your opinion...

if you think dcs is 100% spot on to reality then fine for you,..there are people though who really like what dcs is doing, but are convinced that it could do even more realistic than it already does, and also think that we have the devs capable of improving the sim further.

I haven't ever said that DCS is accurate, simply because I have never even sat in the majority of the modules we fly, let alone flown the real thing. All I can say is that there is more to the flight models than simple guesswork, and I would rather trust Yo-Yo than the armchair amateurs (and please don't think this is a dig at anyone. It does however reflect the level of knowledge available to most of us).

It isn't an opinion that the views stated are meaningless. They are just completely meaningless as reference material and until such point as some empirical evidence is produced to make them anything more than simple opinion without substantiation, they will remain meaningless. It isn't that I am suggesting anyone is wrong for holding them, or that they may not be valid.

A lack of empirical evidence is something that many have been accused of hiding behind on a regular basis, but regardless of people arguing for or against something, ED will not pay any heed to opinion. That's just a fact of life that everyone needs to adjust to.

I did however simply state that to pick on a single factor and ignore everything else is frankly pointless, and I stand by that. What about P-factor? Torque? Undercarriage forces? Do people have the ability - with no access to the numbers in the software - to discern exactly what prop wash is doing? Of course not, and to untangle all the factors involved in just the take off roll is a minefield.

I am not arguing for or against any particular standpoint, I am just asking that people who know no more than I, who want to improve flight models, need to be far far more logical and precise in their approach, or what they say means nothing.

Just producing a few videos doesn't add anything to the argument without knowing the most basic facts, and no one here does know what the take off weight of any of the aircraft featured was. How then can a comparison be made?

That's it, no facts, no opinion, no evidence means anything without context.

Shall we summon Yo-Yo?

...I did however simply state that to pick on a single factor and ignore everything else is frankly pointless, and I stand by that. What about P-factor? Torque? Undercarriage forces? Do people have the ability - with no access to the numbers in the software - to discern exactly what prop wash is doing? Of course not, and to untangle all the factors involved in just the take off roll is a minefield....

i confess i havent flown a p51, fw190, 109 or spitfire, but im happy i am not an armchair pilot only....anyway, please, have a look at the FMoptions.lua file and ask yourself, whether all the entries are based on scientific facts and sources, or whether some of them are guesses themselves...infact this file was adjusted by ED after someone on this forum,did guesswork and adjusted this file to get a more "believable" groundhandling.(based on nothing but feeling).. i am convinced that many things in dcs are just that, estimated guesses, especially when its about groundhandling...

but im also convinced that things like P-factor and the like are also good approximations at best, and there will always be room for improvement.

crosswind-landings are a nice example where you really feel limitations of dcs.yes feel, no hard evidence, but once you have to give rudder into the wind, you know if you have flown in real life, that something isnt quite spot on.

besides, nobody in this thread was complaining or accusing ED of being wrong so far, it was a discussion only with rather questions than claims.

so why screaming for evidence immediately? im sure, Yo-Yo does know himself, that his exceptional flight model will never be 100% spot on, and that there will always be something to fiddle around with, add, adjust.

No one said its the only cause. No one is demanding changes be made. It's just speculation and discussion in a forum, sort of what is supposed to happen here. I was just throwing an idea out there about something I ha noticed and it seems others noticed it too. Maaaaybe at this point the next step is look for charts and submit a bug report after testing.

How do we know how much fuel the aircraft has loaded in the video? Anybody mentioned speculations here?

What I do see for a fact is the small rudder type and very little rudder deflection on takeoff. The take off run was 650m +-30m measured with google earth. Flaps are set to ~6-8 deg, horizontal stab at 0. Thats a starting point I would say.

i confess i havent flown a p51, fw190, 109 or spitfire, but im happy i am not an armchair pilot only....anyway, please, have a look at the FMoptions.lua file and ask yourself, whether all the entries are based on scientific facts and sources, or whether some of them are guesses themselves...infact this file was adjusted by ED after someone on this forum,did guesswork and adjusted this file to get a more "believable" groundhandling.(based on nothing but feeling).. i am convinced that many things in dcs are just that, estimated guesses, especially when its about groundhandling...

 

but im also convinced that things like P-factor and the like are also good approximations at best, and there will always be room for improvement.

crosswind-landings are a nice example where you really feel limitations of dcs.yes feel, no hard evidence, but once you have to give rudder into the wind, you know if you have flown in real life, that something isnt quite spot on.

 

besides, nobody in this thread was complaining or accusing ED of being wrong so far, it was a discussion only with rather questions than claims.

so why screaming for evidence immediately? im sure, Yo-Yo does know himself, that his exceptional flight model will never be 100% spot on, and that there will always be something to fiddle around with, add, adjust.

Screaming? Really? I am afraid you are taking the tone of what i said entirely out of context and proportion.

Yes, it is a debate, but why shouldn't a debate be based on facts rather than presumptions? All I have suggested is that we ought to limit ourselves to something provable. I don't recall anywhere stating that ED was doing anything in particular, and I certainly haven't suggested that what anyone said isn't valid. However to validate something, and raise it out of the world of supposition and fantasy, why can't we have some fact finding?

I can pick anything out of the air and make wild inaccurate statements, but it still remains totally pointless - which everything that has so far been said regarding prop wash and it being the cause of anything.

Nothing was substantiated, nothing can be substantiated, so the whole premise of the debate remains pretty pointless, wouldn't you agree? I just said I trust Yo-Yo more than anyone that has thus far contributed to this. As for looking at the FMoptions.lua, it's all gobbledygook without knowing what is behind the numbers. No doubt you know exactly what it all means?

You have only succeeded in making yourself look pretty foolish by putting words into my mouth. I am however deeply impressed that you're not an armchair pilot. You still have no stick time in any WW2 tail draggers I presume? No, nor do I! I will still trust Yo-Yo as we have nothing better to base our experiences on right now.

armchair amateur, foolish...what else you want to call me?:doh:

You guys complaining about rudder effectiveness on the ground should probably (re-)read this piece here:

https://forums.eagle.ru/showthread.php?t=179253

He explains it very nicely.

And maybe especially this little quote:

Is it more difficult in DCS than in the real world?

 

For those who doubt the validity of how DCS TW aircraft behave, and the difficulties they simulate, I can say with some authority that they are pretty much spot on. Therefore, the problems being described on these forums are also very much representative of the real world. The thing that sets DCS apart from other PC based simulations, and a number of commercial simulators, both leisure and certified which I have experienced, is that so many of these factors deemed undesirable in the real world, are faithfully modelled, along with the challenges they bring.

yes, of course, i dont think anybody is complaining about the rudder when the aircraft is still in a 3point attitude with slow speeds.this is a very good write up from him, but not directly related to this topic,...neither is the effectiveness of the rudder.

im still searching for a certain video on youtube where you see a squadron of 109s taking off...unfortunately i cant find it, but will continue the search.

and sith is of course right as well,the cg will shift with different loadout. no doubt about that.you can easily feel it even during flight,...still i think, what we have in dcs, mind for all ww2 aircraft not just the 109, and what can be observed on different videos(also wartime ones), is very close, but not yet totally perfect. my2c...search for that certain vid continues.

no K4 but waoh, that was some quick tail rise...maybe 5seconds to lift the tail.

Also ~ minute 10:00..