Spitfire(s) trim and elevator in BoX...

[Guest deleted@50488]

The subject of the prevailing elevator down on many shots and videos of various Spitfire models in flight as opposed to what we have in BoX suggests that something is modelled differently in the Spitfire Vb and IX variants available in game.

 

With any combination of weight ( * )  / speed / power I am never able to set elevator trim in such a way that I can observe the elevator even if just slightly deflected down without the aircraft "wanting" to dive.... Flying level always actually requires a bit of Up elevator, which is not in sync with what we can observe IRL ( ? )

 

One among many references to this "Spitfire feature" : https://forum.keypublishing.com/showthread.php?122379-Spitfire-flight-control-rigging

 

( * ) only based on fuel load, no ammunition since that's the way those aircraft are seen flying on those shots and videos.

Edited May 30, 2018 by jcomm-in-combat

[AndyJWest]

Possibly the BoX FM doesn't correctly model the downward deflection of the airflow behind the wing? I'm not sure it really matters much though, since 'flying right' is more critical than minor graphical issues.

[Guest deleted@50488]

This elevator deflection is well documented at the bottom of Fig. 9 on : https://ntrs.nasa.gov/search.jsp?R=19930092582

[ACG_Smokejumper]

On 5/28/2018 at 1:31 PM, AndyJWest said:

Possibly the BoX FM doesn't correctly model the downward deflection of the airflow behind the wing? I'm not sure it really matters much though, since 'flying right' is more critical than minor graphical issues.

 

Is it just a graphical issue or a flight model flaw though? I'd like to see a modern combat flight sim beat the older ones. Cliffs for example shows the proper level flight elevator angle.

 

If it's just graphics fine, hopefully a fix is in the works but I wonder if it's an FM problem. If visual positioning is the physics math this means this Spitfire is incorrect.

 

Edited May 30, 2018 by 7./JG26_Smokejumper

[Guest deleted@50488]

I strongly believe it's an FDM issue too... Otherwise I wouldn't really mind that much...

 

There are two areas where I think the Spitfires in BoX are disagreeing with RL data. This is one of them.

 

To experiment simply start the Spits, any of the models ( less the clipped wing model because I haven't seen any data for those... ) and it'll start trimmed by default for cruise conditions. Take control of it and try with various combinations of weight / fuel and speed... You will always have to pull the stick to keep it level once "AP" is disconnected... which is exactly the opposite of what the charts show, or you'll have to set the trim towards the tail-heavy side.

 

The other flaw IMHO is the rather tame sideslip induced by prop effects. Again based on available charts from test flights like the NACA one linked above one can see how sensible to higher power settings, specially at lower CAS, the aircraft is regarding the development of considerable sideslip angles. In BoX  we can takeoff and practically get our feet of the rudder. While maintain wings level there is almost imperceptible sideslip at least depicted by the turn & slip gauge, down to just a bit above stall.

 

Or set yourself inflight, add full power and start a steep climb without touching the rudder. Do it with and without default trim settings, and watch down to what speeds and up to how high AoAs you can reach without practically no need for rudder.

 

Edited May 31, 2018 by jcomm-in-combat

[unreasonable]

I cannot add anything about sideslips tame or otherwise - not sure what figures you think the indicator should reach.

 

But on the subject of the trim, I almost fully agree - but if I trim fully (or nearly) tail heavy, full tanks, I need a forwards stick pressure on my G940 (FFB with a little spring centering on)) to fly level. It is quite definite - but easily trimmed out. The odd thing is that when you look at outside view in this case the elevator appears to be level with the stab: if it is tucked below, it is just about imperceptible.  So there may be some element that is controller related, and it may be a mismatch between graphical representation and FM.  But overall I agree it suggests the centre of gravity (and/or lift or whatever) is fractionally out. Worth asking about.

 

On another matter, Spitfire related, may or may not be trim related, I find that I cannot do an approach as set out in the PN because at the rpm and boost recommended for the stages of the approach, (2650 and -2 for level approach, -3 for -500ft/min then 3000rpm -3/-4 for final) the damn thing will never slow down far enough to lower gear!  I have to put the throttle completely to idle - which the PN says should only be done once on the ground.  I wonder if you have the same experience?

Edited May 31, 2018 by unreasonable

[Guest deleted@50488]

@unreasonable,

 

I'll try those approach / landing tests and report back.

Regarding the sideslip mentioned above, page 14 of the NACA report linked above starts describing it and the charts 9, 10 and 11 of the same document further can give an idea of how much sideslip angle should be given by the turn & slip indicator.

 

P.S.: Confirmed your observations regarding approach and landing configuration - indeed impossible to bleed off speed ! Good one !

Now, again about the sideslip, the strange thing is that, if we set the rudder trim to it's supposedly neutral setting, by hitting the RESET TRIMMERS key, we have more indicated sideslip at higher speeds / lower AoAs than at low speed / high AoA ( ? )  Really weird I believe...

 

Edited May 31, 2018 by jcomm-in-combat

[unreasonable]

@jcomm

 

Thanks - will try some pull ups. That report is a about tests on a Mk V A, my comments above were based on observations on the BoBP Mk IX.

I will do some pull ups and see if I concur with you on the slip numbers.

 

Edit - I do. Looked at two elements from the report: the comment that at low speed with level wings there is appreciable amount of L sideslip (presumably with neutral rudder trim?) and the sideslip angle during pull ups with feet off the rudder bar.  On the first I got maybe 2 degrees: on the pull ups almost nothing. That is for both MkV and IX.

 

Coming from RoF, I had rather got used to the controls not being well harmonized; quite rightly for most WW1 aeroplanes.  I have to admit I find flying now a little bland since the roll/yaw update.  

Edited May 31, 2018 by unreasonable

[Guest deleted@50488]

Thanks  @unreasonable, let's hope the devs read these topics at the forum, and give some feedback ( ? ) 

 

 

Edited May 31, 2018 by jcomm-in-combat

[ACG_Smokejumper]

10 hours ago, jcomm-in-combat said:

@unreasonable,

 

I'll try those approach / landing tests and report back.

Regarding the sideslip mentioned above, page 14 of the NACA report linked above starts describing it and the charts 9, 10 and 11 of the same document further can give an idea of how much sideslip angle should be given by the turn & slip indicator.

 

P.S.: Confirmed your observations regarding approach and landing configuration - indeed impossible to bleed off speed ! Good one !

Now, again about the sideslip, the strange thing is that, if we set the rudder trim to it's supposedly neutral setting, by hitting the RESET TRIMMERS key, we have more indicated sideslip at higher speeds / lower AoAs than at low speed / high AoA ( ? )  Really weird I believe...

 

 

 

Also agree about side slip. I do not have to touch my rudder trim as often as I did in Cliffs. Now I know video game to video game comparison is not ideal but I do feel they really nailed the Spitfires in Cliffs. The anecdotal stories align with the Cliffs version of a video game Spitfire where as the BoX one is a touch off, in my opinion of course.

 

An in game comparison is the 109, I stand on the ruder a lot to correct slip.

Edited May 31, 2018 by 7./JG26_Smokejumper

[unreasonable]

Further observations on the Spitfire:

 

1) It does not seem to slip left when you pull up from level flight with the rudder trimmed: but, if you push the nose down, even a little, it swings right - it is easy to get the slip indicator at the R hand stop with only a small push. When you then stop pushing, the slip indicator returns to the upright position.  So maybe not so far off the NACA test?

 

2) On a number of occasions now, when I have pressed the key to raise gear after take-off, my engine has stopped!  Good practice for straight ahead emergency landings, I suppose... I have not yet found a pattern in when it does or does not do this. Anyone else had a similar incident? 

 

[Guest deleted@50488]

3 hours ago, unreasonable said:

Further observations on the Spitfire:

 

1) It does not seem to slip left when you pull up from level flight with the rudder trimmed: but, if you push the nose down, even a little, it swings right - it is easy to get the slip indicator at the R hand stop with only a small push. When you then stop pushing, the slip indicator returns to the upright position.  So maybe not so far off the NACA test?

 

2) On a number of occasions now, when I have pressed the key to raise gear after take-off, my engine has stopped!  Good practice for straight ahead emergency landings, I suppose... I have not yet found a pattern in when it does or does not do this. Anyone else had a similar incident? 

 

 

Never experienced that kind of engine failure. Strange ?

And yes, I acknowledge the effects described in 1) unreasonable. 

[ACG_Smokejumper]

Have any devs looked at this? I'd like to know if it's a visual bug or a FM correction that needs to be made.

 

Another issue I am not sure about is control column wobble you can only feel with force feedback. The stick does not go to centre out of a bank. It rocks the stick forward and back. Not sure if this is accurate. Another reason I dislike it is that many of your sticks are showing age in the gears and there is slop in the middle. I've got 5 of the stick so I can start tearing them apart but for those without tool skill this makes aiming a bit trickier.

 

Only the Spitfire and the P39 display this trait. It's a new feature that no other fighters have with force feedback.

 

I'm not sure its accurate at high speed but no idea where to look to get evidence.

Edited June 8, 2018 by 7./JG26_Smokejumper

[VesseL]

50 minutes ago, 7./JG26_Smokejumper said:

Have any devs looked at this? I'd like to know if it's a visual bug or a FM correction that needs to be made.

 

Another issue I am not sure about is control column wobble you can only feel with force feedback. The stick does not go to centre out of a bank. It rocks the stick forward and back. Not sure if this is accurate. Another reason I dislike it is that many of your sticks are showing age in the gears and there is slop in the middle. I've got 5 of the stick so I can start tearing them apart but for those without tool skill this makes aiming a bit trickier.

 

Only the Spitfire and the P39 display this trait. It's a new feature that no other fighters have with force feedback.

 

I'm not sure its accurate at high speed but no idea where to look to get evidence.

 For me Mig is the same. And also P-40 slightly but not bad. Rocking controls when should be centered. Force feedback issue?

[ACG_Smokejumper]

Not sure. It feels intentional. I think you are correct on the Mig3. I notice it there too. Thanks.

 

EDIT///

 

It's not the P39 that has the wobble, it's the Mig3 and Spitfire V. Have not flown the IX yet.

Edited June 9, 2018 by 7./JG26_Smokejumper

[ACG_Smokejumper]

Still nothing?

 

One of the few things we can easily show to be wrong is the elevator position. I'd like to know if visual position is linked to FM.

[unreasonable]

44 minutes ago, Agathos_Deimon said:

 

Which version of the pilot notes? The version found at Zenos Warbird or Avialogs doesnt give specific boosts and RPM for the approach and it only mentions a need for an power approach in the case the aft fuselage tank contains full fuel (see page 27). I have no problem approaching and landing the spit according to those PN and as describe at pages 26/27.

 

In general i find planes in IL2 BoX keep there speed very well. Found that already when i purchased BoS in Xmas Sale 2017 and tested FW190A3 and the Bf190s. But its a finding accross all planes, that to deaccel in the approach you have to throttle way back and best increase AoA alot or even go into some climb to get the speed down for landing config.

 

Yes they do - see section 49 Beam Approach. If those settings work for a beam approach they should work for any approach, but they do not.

 

I have no problem landing the Spitfires either, now I have got used to their unwillingness to slow down: just takes idle throttle and patience.  But you have to have 5-10 mph more speed than the PN says for any given stage because the game plane has no instrument error. 

 

This is not a real complaint BTW - just an observation about how the game works. 

[unreasonable]

 I was testing the Beam approach values as an experiment simply because they are there: normally I just do it by feel plus basic speed limits for cockpit, gear and flaps.  I found that even after adding a generous PEC to the quoted figures (ie allowing a higher speed than the printed values) I could not get close to the recommended speeds at the recommended power settings - I would be way too fast.  jcomm seems to have found the same thing.

 

You could well be right that it is a general feature: but if it is it is FM not instruments IMHO, since in this case you can adjust for PEC fairly accurately.   Maybe it is just the damp English air that is not modeled.