Flight model thoughts

And, the same sudden increase in the pitch attitude and AOA will occur as I have described when the flaps are raised too quickly. I had done this as a student pilot, 50 years ago.

 

Now, back to the Spitfire. I hope.

We all about Spitfire even when wonder off topic :)

There are two things I'm trying to verify:

1. Slight right stick on take off in order to compensate for prop tendencies. I'm trying to find any mentioning of this in books and internet, but so far no joy

2. Extreme pitching moment due you to flap deployment which it seems in my case producing negative longitudinal stability. Meaning when I drop flaps down, trim elevator all way aft, and let go controls Spit will continuously dip nose to the negative pitch which in turn forces me continuously back pressure on the stick. I don't know what it is. Limitation of elevator trim or actual Sit tendency. Again none mentions it in the books..

P.S.At the moment I use linear curves for my TM Warthog per Yoyo setup

Sometime ago in a thread I can't find right now, Yo-Yo gave users the choice among various possible implementations of downwash effects on pitch... There choice was to force the pilot to actually push / pull the stick accordingly like irl for each aircraft, and this is achieved both in FF and non-FF controllers by displacing the virtual stick.

Presently the displacement is probably a bit overdone, I really don't know, because what I read is that there was just a very slight trimmed AoA variation due to flap deployment. There are a worth of sources from here:

http://www.spitfireperformance.com/spitfire-V.html

including the NACA report for the VA variant:

http://www.wwiiaircraftperformance.org/NACA-Spitfire-V-Flying.pdf

... where it is mentioned starting on page 5 "Longitudinal Stability and Control"...

(P.S.: just found you can skip to page 11, Trim change due to power and flaps... )

In another sim I used the Vb wasn't so "intense" in this effect when flaps are deployed / retracted inflight.

Regarding the use of right stick deflection I also can't see it mentioned other than in an article, and in youtubes. It can actually be observed in some cockpit footage at youtube, during takeoff, but as Yo-Yo once pointed out, it is useless at the beginning of the takeoff run since the ailerons will take some good "q" to become alive... It can be used in anticipation though, because near the end of the takeoff run, specially at higher power settings, rudder trim only can be unsufficient ( ? )

You are comparing apples and oranges here as we are talking about flap extension/retraction and not flaring in ground effect.

 

@VinnieJones, I've flown a lot of planes with manual flaps but I haven't encountered a single one that starts to climb when rapidly retracting the flaps.

Most plane have that even written in the POH, not to raise the flaps too fast, or in one step, to avoid sinking.

It’s normal practice to establish common phraseology. No apple or oranges her.

I also flown/instruct in many airplanes with manual flap. First come to mind C172B and PA28. I concur I don’t remember any of them do anything but sinking after rapidly retracting flaps

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It’s normal practice to establish common phraseology. No apple or oranges her.

 

I also flown/instruct in many airplanes with manual flap. First come to mind C172B and PA28. I concur I don’t remember any of them do anything but sinking after rapidly retracting flaps

 

 

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bbrz,

In that experience I had as a student, the nose pitched up suddenly and violently. There is no room for debate about that happening or why. Of course, the plane began sinking AFTER that. It had suddenly lost lift.

So, how about we all cut the “mines bigger than yours” crap, and end this?

bbrz,

 

In that experience I had as a student, the nose pitched up suddenly and violently. There is no room for debate about that happening or why. Of course, the plane began sinking AFTER that. It had suddenly lost lift.

 

So, how about we all cut the “mines bigger than yours” crap, and end this?

I’m going to reply since you quoted me.

We are sharing our experiences. Some of us fly for pleasure, some are commercially, some are teaching ..it doesn’t matter who fly and how. We are trying to establish common ground in understanding of flight physics relative to Spit in DCS to the best of our knowledge. So sorry if it hurts you feeling it wasn’t my intent at all .

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I’m going to reply since you quoted me.

We are sharing our experiences. Some of us fly for pleasure, some are commercially, some are teaching ..it doesn’t matter who fly and how. We are trying to establish common ground in understanding of flight physics relative to Spit in DCS to the best of our knowledge. So sorry if it hurts you feeling it wasn’t my intent at all .

 

 

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My feelings were not hurt. It was my experiences that were being questioned.

My feelings were not hurt. It was my experiences that were being questioned.

Experience affect perceptions. So we all have different perceptions based on our experiences. Sharing them not a reason to get hostile about it

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It's very easy to be tricked by our sensorial input...

Then, some aircraft pitch down, while most pitch up, on flap deployment... What I really like to see is that a flight simulator tries, within what is possible for the available computing power, to replicate as close to real as possible all of these effects, preferably without any sort of "scripted" effects.... DCS is doing a great job for sure. Can it get better ? Of course it can.... and will most probably because the Spitfire is still in EA.

Am I missing something? With DCS Spit I have to fly with 1 notch nose up trim. With A2A and CloD Spits I am flying 1 notch nose down trim. I heard that Spitfire is a tail heavy plane.

Am I missing something? With DCS Spit I have to fly with 1 notch nose up trim. With A2A and CloD Spits I am flying 1 notch nose down trim. I heard that Spitfire is a tail heavy plane.

If you're not using a FFB controller, make sure you untick FF in one of the configuration menus, I don't recall exactly which one though :-/

I always have to trim the Spitfire IX in DCS nose heavy, or push the stick inflight ... and even looking at the tail you'll clearly see, just like in many real world youtubes, the elevator slightly displaced down...

I’m using warthog hotas. I checked that ff is unticked. Whats going on? :D

@ Jcomm, Vino refers to trim indicator, so type of his joystick is irrelevant.

@ Vino, I've been wondering about the same thing for a long time. I think it's the question of interpretation of how trim indicator works. Note that in DCS Spit manual, it's stated that neutral position of elevator tab equals two notches up from the center (?). Thus when we have to fly with one notch up to keep the plane level in DCS, it supposedly corresponds to roughly about one notch of trim "nose heaviness" (as can be indeed seen on external view of the elevator in flight). That would be an equivalent of one notch down in other simulators you mentioned, which I presume interpret center position of indicator arrow as the neutral one.

So the plane in all sims actually flies the same way, only the trim indicator causes confusion. Now, which implementation of that instrument is correct for "our" Mk IX? I don't know, though It's difficult not to have doubts about DCS's version, after watching vids like that one:

@ Jcomm, Vino refers to trim indicator, so type of his joystick is irrelevant.

 

@ Vino, I've been wondering about the same thing for a long time. I think it's the question of interpretation of how trim indicator works. Note that in DCS Spit manual, it's stated that neutral position of elevator tab equals two notches up from the center (?). Thus when we have to fly with one notch up to keep the plane level in DCS, it supposedly corresponds to roughly about one notch of trim "nose heaviness" (as can be indeed seen on external view of the elevator in flight). That would be an equivalent of one notch down in other simulators you mentioned, which I presume interpret center position of indicator arrow as the neutral one.

 

So the plane in all sims actually flies the same way, only the trim indicator causes confusion. Now, which implementation of that instrument is correct for "our" Mk IX? I don't know, though It's difficult not to have doubts about DCS's version, after watching vids like that one:

AH! Ok Art-J, I didn't notice he was referring to the trim gauge... thx for that.

Good question regarding which one is correctly implemented. In IL2 BoS we read 0% trim when the needle is up, like during landing on your video. That's the reference I've been using for neutral pitch trim, also in DCS.