Flight Dynamics

[Macpah]

Don't argue with Gerry... you can't win... just simply walk away. He is the singular person I have on ignore on the entire internet.

 

Will do, thanks Ed. :wink:

[ZG862]

Stall speed is fixed in FSX?

 

Hmm. Don't think so. Stall has a lot more to do with angle of attack than airspeed. There's a section in the .air file that defines the position of the wing centre of lift for a given angle of attack which suggests to me (aerodynamics numpty) that this is modelled in the FDE. If/when I get my head around this I'll give a better answer.

 

Z

[TrafficPilot]

 

 

Isn't this what you're talking about?

https://www.youtube....h?v=fumnit13r80

 

Yes - although in that example the aircraft appeared to stall around the published straight and level power off stall speed. If it was realistic that Tomahawk (and ANY aircraft attempting that manouvre) would stall at a much higher airspeed due to the excessive bank angle.

 

For anyone interested in learning more I recommend "Stick and Rudder" by Wolfgang Langewiesche. First published in 1944 and still the best book available today. Available at most good online bookstores!

 

Cheers

Adam

[jcomm]

Or, See How it Flies

 

But I also particluarly like to read an article, published in the "Stick and Rudder" section of www.aviationsafetymagazine.com, in April 2006 under the tittle:

 

"Cross-Coordinated"

[JB3DG]

How is that possible when it isn't modelled in the FSX FDE?

 

I am talking about the stall speed increasing as the angle of turn tightens - as in real life. A "gotcha" which has killed lots of novice pilots in the past.

 

It IS modeled in FSX. Its a simple basic. Bank angle increases, vertical component of lift decreases. Higher angle of attack to maintain level flight. Reduce speed, reduce lift. Higher angle of attack to maintain level flight. Exceed critical AoA and level flight can no longer be maintained and the aircraft falls out of the sky.

 

I don't know who came up with the idea that it doesn't exist in FSX but that is complete hogwash. I fail to see how it is even possible for it to not exist unless someone feeds complete garbage into the airfile and cfg....even then.

[denali]

 

 

it's really a very interesting read (if you love absurdly complex math!).

 Can you tell me what the book is?  I love acm!!  I have it with my afternoon tea.

 

 

Systems modeling is being moved to the 'exterior'... they're trying to make it so you can inject your own engine simulation, as example.

 This is what I remember as the current model for FD.  It's probably best to leave it up to the individual aircraft models and their creators to make them as realistic as possible, and support that with any hooks they can provide.

 

 

I have Kuchemann's book.

 Wow, this is strangely relevant to something else I am working on.  Can anyone tell me if this Kuchemann is the same one?   http://www.merga.net.au/documents/RP_Prasad_1994.pdf  This is a sincere question.  Sorry for the digression.

If you can't tell, I'm not even quite done reading the thread, sorry.  I know what the other book is already, thanks.

[vololiberista]

 Wow, this is strangely relevant to something else I am working on.  Can anyone tell me if this Kuchemann is the same one?   http://www.merga.net.au/documents/RP_Prasad_1994.pdf  This is a sincere question.  Sorry for the digression.

If you can't tell, I'm not even quite done reading the thread, sorry.  I know what the other book is already, thanks.

 

The Aerodynamic Design of Aircraft (Aiaa Education Series)7 Dec 2012

by Dietrich Kuchemann

[mgh]

The Dietrich Kuchemann (of Concorde wing fame) died in 1976.

[mikea76]

I was disappointed with the A2A Cherokee. Great looking aeroplane with a fantastic VC but the handling IMHO is nothing like a real Piper Cherokee. The A2A model wallows all over the place and as for the trim?! Full up elevator trim required on final approach and STILL not enough to trim out the flare? If that is how their "real world" Cherokee flies I'd put it in the hanger for some major attention to the trim tab.

 

 

Its funny I was having the same problem with needing full up trim on final as well.  I read some piper forums and there is quite a bit of discussion on how to land the real 180 properly  after reading some different techniques and  a lot of practice I came to the conclusion that I was flying it like a tapered wing cherokee now  I can get greasers out of it without full up trim, I am normally pretty light so about 70 MPH over the fence you will be back on the yoke a little. I have checked my trim after landing and I am pretty close to neutral maybe a little nose up trim.  

 

I have a question have you flown a real 180? the reason I ask is I tried flying it like the 161 that I currently train in and that caused a LOT of issues for me.  

 

I may be 100 percent wrong on this but I think some of the issue is with our controls, unlike a real plane where the feel changes with airspeed  our center point is fixed and the feel is fixed in our sim controls. This causes a lot of problems with RW pilots.

[TrafficPilot]

I have a question have you flown a real 180? the reason I ask is I tried flying it like the 161 that I currently train in and that caused a LOT of issues for me.  

 

Hi Mike,

 

I've flown a few versions of the PA-28 including a '66 140 and currently train students on a couple of 161 Warriors. I just find the general handling of the A2A Cherokee to be quite unpleasant - nothing like the real thing which is easy to fly even for beginners.

 

I have recently reinstalled P3D so will reinstall and have another go after reading your post

 

Cheers

 

Adam

[ZG862]

... and currently train students on a couple of 161 Warriors. ...

 

Hi Adam,

 

I'd be interested in a real world instructor's opinion of which areas of the FDE really stand out as not tallying with your experience of the real world. I did see your comment about stalling in steep turns and I suppose it is pretty difficult to separate FDE behaviour from the behaviour of a particular aircraft - but nevertheless, what's your view?

 

Z

[ErichB]

Hi Adam,

 

I'd be interested in a real world instructor's opinion of which areas of the FDE really stand out as not tallying with your experience of the real world. I did see your comment about stalling in steep turns and I suppose it is pretty difficult to separate FDE behaviour from the behaviour of a particular aircraft - but nevertheless, what's your view?

 

Z

 

 

In my view, the disgruntlement regarding general handling of GA aircraft in a flightsim is due to the controllers we use.    I think A2A do a superb job on modelling, but if you are flying a GA aircraft with a controller that has no force feedback and little resistance - or a controller with the centering force of a ruler, you can fling it all over the shop, and it really doesn't feel real.  Adam will be more qualified to comment as an instructor, but from my own RW experience, (long time ago) the cherokee controls feel solid and has a resistance which allows you to feel the aircraft in a way that a £100 Saitek yoke will not. In the real cherokee (or cessna) you can feel a steep turn on the controls and your body which you just cannot in a sim.  The tendancy is therefore to over-control  and stall and is actually is one of the least gratifying experiences in a sim.    I would be interested to hear opinions from someone using a PFC yoke.

[ZG862]

In my view, the disgruntlement regarding general handling of GA aircraft in a flightsim is due to the controllers we use.    I think A2A do a superb job on modelling, but if you are flying a GA aircraft with a controller that has no force feedback and little resistance - or a controller with the centering force of a ruler, you can fling it all over the shop, and it really doesn't feel real.  Adam will be more qualified to comment as an instructor, but from my own RW experience, (long time ago) the cherokee controls feel solid and has a resistance which allows you to feel the aircraft in a way that a £100 Saitek yoke will not. In the real cherokee (or cessna) you can feel a steep turn on the controls and your body which you just cannot in a sim.  The tendancy is therefore to over-control  and stall and is actually is one of the least gratifying experiences in a sim.    I would be interested to hear opinions from someone using a PFC yoke.

 

I agree with much of this Erich, though I would point out that the real control resistance can vary with both airspeed, engine speed and control location on the airframe (e.g. an elevator can be effective at near stall on the back side of the power curve because they have been located in the prop wash when at the same time the ailerons can be quite loose - same thing may not apply at all on a pusher prop). To model this well, the FDE would presumably need to factor in the control effectiveness due to prop wash - and I'm not sure that ESP/FSX/P3D does. I think someone mentioned above that A2A appear to programmatically add rudder with engine speed which I am sure can be tuned to give a realistic yaw effect due to prop wash but its not the same as directly handling this in the dynamics engine. 

 

Z

[mikea76]

Hi Mike,

 

I've flown a few versions of the PA-28 including a '66 140 and currently train students on a couple of 161 Warriors. I just find the general handling of the A2A Cherokee to be quite unpleasant - nothing like the real thing which is easy to fly even for beginners.

 

I have recently reinstalled P3D so will reinstall and have another go after reading your post

 

Cheers

 

Adam

Hi Adam,

 

I have read your posts before and I knew you had a lot of real world experience so I was wondering if you flew this particular model.

 

I noticed in the a2a Cherokee that if you trim out all the pressure on the yoke for at 70-80 mph approach you will be way up on the trim and the plane will be twitchy as hell in the flare.

 

However if you keep slight back pressure ( closer to where the elevator would be neutral in the real plane at approach speeds) you don't need as much nose up trim and it lands nice without the porpoising

 

IMHO our sim controls cause this

[mgh]

In addition FSX not having force-feel (if any), it also doesn't have motion cues nor realistic visual clues either.