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Old 04-13-2017, 04:20 PM   #1
Alfredson007
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Default The only issue with Flight Model

First of all i must say, that, while obviously i am not a real Spit pilot i must say this must be the closest to a real deal i've experienced.

There is only one thing that, in my mind seems unreal. When i ease the throttle there's hardly any reaction to the plane's pitch attitude. I admit that due to the changing twisting and turning reactions of the propeller (which are awesome) it is a bit hard to diagnose what the plane is doing but i've even seen nose up reaction after significant power reduction.

Now, since this is a prop plane and the horizontal stabilator is where they usually are - behind the prop, reducing thrust should ~immediately weaken the airstream over the stabilazer making the nose go down, and the plane should climb when adding thrust. This only happens after the speed reduction of reduced thrust which is not right in my mind.

What'ya think?
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Old 04-13-2017, 04:23 PM   #2
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The spitfire is tail heavy, and the elevator is pointed down slightly in cruise to compensate for this and reduce drag in hard turns. This leads to some rather fiddly pitch handling when you're not in a dogfight.
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Old 04-13-2017, 05:25 PM   #3
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Quote:
Originally Posted by Alfredson007 View Post
First of all i must say, that, while obviously i am not a real Spit pilot i must say this must be the closest to a real deal i've experienced.

There is only one thing that, in my mind seems unreal. When i ease the throttle there's hardly any reaction to the plane's pitch attitude. I admit that due to the changing twisting and turning reactions of the propeller (which are awesome) it is a bit hard to diagnose what the plane is doing but i've even seen nose up reaction after significant power reduction.

Now, since this is a prop plane and the horizontal stabilator is where they usually are - behind the prop, reducing thrust should ~immediately weaken the airstream over the stabilazer making the nose go down, and the plane should climb when adding thrust. This only happens after the speed reduction of reduced thrust which is not right in my mind.

What'ya think?
Was the Spit perfectly trimmed for a given airspeed and level flight when you performed this test?
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Last edited by OnlyforDCS; 04-13-2017 at 05:29 PM.
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Old 04-13-2017, 05:47 PM   #4
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Originally Posted by OnlyforDCS View Post
Was the Spit perfectly trimmed for a given airspeed and level flight when you performed this test?
Absolutely. But as i said, the test is not very easy to perform accurately, since the power reduction causes torque changes etc and you need to keep the plane level, so a hands off test is quite impossible but anyway no pulling back is necessary and it indeed might climb.

The P51 mustang however, starts to dip nose if you retard the throttle.
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Old 04-13-2017, 05:50 PM   #5
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Quote:
Originally Posted by Alfredson007 View Post
The P51 mustang however, starts to dip nose if you retard the throttle.
Because of its differently configured center of gravity and horizontal stabilizer.
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Old 04-13-2017, 07:17 PM   #6
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I look forward for stiffness to be added ( with dynamic pressure ) to the rudder axis, to better balance the feel of the three controls.
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Last edited by jcomm; 04-14-2017 at 09:49 AM. Reason: My rubish in the original post...
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Old 04-13-2017, 09:01 PM   #7
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Originally Posted by Pocket Sized View Post
Because of its differently configured center of gravity and horizontal stabilizer.
Well you might be right. I just do not figure this out. If the plane is "tail heavy", or the CoG is more aft than usual, ok they slightly increased the AoA of the stabilazer, but shouldn't it still react to airflow preetty much normally...? Tailheaviness would sound really bad. The Airacobra was tail heavy in some situations and it could end up in fatal accidents for that, but its engine was mounted behind the pilot...
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Old 04-14-2017, 03:21 AM   #8
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Only airspeed is going to change the lift when you reduce the throttle, if nothing else is changed. One thing my group has noticed is that when you reduced the throttle, the plane wants to yaw to the left, the same as when you add throttle. That's fine and correct when adding power due to torque and other factors, but definitely shouldn't be happening when reducing power.
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Old 04-14-2017, 04:30 AM   #9
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Quote:
Originally Posted by jcomm View Post
Unfortunately while an update with rudder forces isn't issued I can't really find the flying characteristic of the DCS IX that accurate :-/
Based on what?
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Old 04-14-2017, 09:45 AM   #10
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Quote:
Originally Posted by SiThSpAwN View Post
Based on what?
Based on my more than 40 hrs in DCS's Spitfire :-)

Well, jokes apart, and while you should always filter my exclamations .. I believe it was even mentioned by developer on some thread I can't find right now.

Of course it's not impeditive or a show stopper. It can somehow be tamed down using, for instance, 25 % curve for rudder axis - that's what I am using...

Anyway, post amended ;-)

Here's that interesting "NACA" report: http://jsbsim.sourceforge.net/spit_flying.pdf
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Last edited by jcomm; 04-14-2017 at 09:56 AM.
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