Rudder output correct?

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heskelin
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Rudder output correct?

Post by heskelin » 14 Oct 2006, 23:26

I find Safirs responce to rudder input a bit unusual. The ac gets some yaw input but there seems to be no affect on speed or descent. Try a landing with opposite rudder/airelon.

I have almost zero real life experience on any ac. A few hours on c172 does not qualify me as master.

Can someone confirm that rudder works as it should on Safir?

Normally I would not care at all but with this suberb product I need to know!

snave
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Post by snave » 15 Oct 2006, 03:02

Check your realism settings in the sim and your rudder pedal calibration.

I can sideslip the Safir with ease using rudder pedals and a FF joystick.
Simon Evans

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Sebastian
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Post by Sebastian » 29 Apr 2007, 14:38

The Safir cannot sideslip - even with maximum realism settings.

Try the Realair-addons: Decathlon, Citabria, Scout, Spitfire, Marchetti. These can sideslip in its sense to reduce speed significantly, the Safir can fly with sideslip settings, but it won`t reduce speed.
Greetings from the Ruhrgebiet, Germany

Sebastian

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snave
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Post by snave » 29 Apr 2007, 19:54

Mine does... and be VERY careful about assuming the role of sideslip is to decrease airspeed.
It is not, although it is often a side-effect. The primary function of SIDESLIPp is to alter the relative aerodynamic effect, to xchange the relative track without altering the heading of the aircraft. And is primarily used in crosswind landings...

What you are confusing here in your terminology is `sideslip` with FORWARD-slip:
Forward-slip is used to INCREASE rate of descent WITHOUT INCREASING airspeed. Note the very different cause/effect criteria!

One does not use `sideslip` to slow an aircraft. Indeed the POH may stipulate the maximum airspeed at which such actions may be performed as they fall within the Va (Maximum Manouevring Speed) envelope, as it usually involves near-maximum deflection of controls.

One slows to use sideslip, not uses sideslip to slow. ;-)

Therefore - and please don't take offence - but your comment is meaningless.
:D
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Sebastian
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Post by Sebastian » 29 Apr 2007, 21:08

Thank you snave for this new info about slipping. In the german terminology we do not make differences between sideslips and forward-slips. Slipping is a favorite theme in our bushpilots forum as many of us love to fly the Realair Decathlon which is a flapless plane that has to be flown with a lot of forward-slipping to reach small bush bases.

Nevertheless, as you call my comment meaningless, I - and so do some others of us - would like to know about the Safir`s ability to perform effective forward-slipping. My impression is that the rudder-effectivness is to weak, but I know that a lot of real airplanes are not designed to perform such manovers. Do you know more concerning this?
Greetings from the Ruhrgebiet, Germany

Sebastian

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snave
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Post by snave » 30 Apr 2007, 02:14

As I have said in another reply, I have no stick time in a Safir to be able to comment on whether the real one can sideslip - but given that the aircraft was designed in the Forties I'd be surprised if it couldn't.

However, the Safir was fitted with split flaps, a particular type of wing flap (invented by Orville Wright, as it happens) that is known for increasing drag MORE than increasing lift. Other types of flap operate differently in the lift:drag ratio, and one may presume that split flaps were chosen for the Safir because they provide additional lift in the first position, then only increasing drag after that, allowing for steep descents without increas in airspeed - which is also the purpose of the forward slip. The DC-3 was also fitted with such flaps, to keep landing speeds low to reduce float and bounce.

So the forward slip would be kind of redundant in the Safir but I can certainly envisage situations where a pilot might prefer the forward slip to the drag of flaps. The Safir was aerobatic, as seen in the flight manual here:
http://www.fcfk.com/safir/sb91/manuals/AFM91B_i2.pdf
so there is no doubt in my mind it would have been approved for slips and would have had the control authority to perform them.
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Sebastian
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Post by Sebastian » 30 Apr 2007, 02:59

So, when the FS-Safir is not able to do forward-slips, it is some kind of unrealism in the flightmodel of the Safir!?!? For sure, it cannot perform forward-slips in FS in conjunction with additional drag effects.

Of course, it has flaps and I also know split flaps of that flying era were exactly designed in the way you described.

BTW: In the DC-3, as I read, it was a not uncommon technique to raise flaps up a step just before touchdown to decrease lift and prevent bouncing effects - so far concerning the lonesome drag effect of full flap settings with split-flap planes ;-)
Greetings from the Ruhrgebiet, Germany

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snave
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Post by snave » 30 Apr 2007, 17:43

No, so we come full circle to my original reply. On my computer I am able to perform forward slips and sideslips with ease. I can perform crosswind approaches using either wing-low or crab technique. For sure.

It is therefore not the flight modelling that is wrong, it is something in your controllers or setup. Perhaps you could give us more details of your controllers and how you have the simulator settings within the sim. The main reason the rudder doesn't do as it should is either because you have autorudder enables, or because you have a previous flight which you have saved with Yaw Damper engaged. Start with the default flight in the Cessna, then switch to the Saab.

BTW, the DC3 technique you refer to was NOT to decrease lift, but to decrease float-in-ground-effect caused by the cushioning effect of the large underside surface area of the wing and the extended flaps trapping the air. I have commented previously on how just a few knots fast and the Sibwings Safir does exactly the same thing... and this was confirmed as something also witnessed in the real thing.
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Sebastian
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Post by Sebastian » 30 Apr 2007, 21:29

Hi snave, I thought the from you described float-in-on-ground-effect is nothing else than a lift effect, but that doesn`t matter here.

To my controller setup: I call myself a serious flightsimmer :-D , so my FS has never seen an autorudder and I did not fly a yaw damper controlled aircraft before. Instead, I mostly fly the RealAir Decathlon, Spitfire und Sibwings Safir.

I use a Logitech Force Feedback Stick with standard setup. I am really curious how you can do real effective forward-slips with the Safir - everyone in the Bushpilots.net-forum agreed with that. It would be nice to see a video of one of your flights. Crosswind-landings with sideslips are something else than about additional 500 to 1000 feet sinkrate per minute more during forward-slips. The RealAirs can do that, but they are the only planes I know in FS. The freeware Airhead Decathlon should do either, but here noone of our bush-pilots has ever managed to fly effective forward-slip approaches as well. With the RealAir Decathlon (flapless aircraft) I can sink with more than 1500 feet per minute without increasing speed.

So far, this is no problem with the Safir, because, as I already wrote, not every plane is designed to perform forward-slips.

But solution for this question is near. One of our forum members is real-Safir-experienced, I will ask him in our forum and report on this here later.
Greetings from the Ruhrgebiet, Germany

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snave
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Post by snave » 01 May 2007, 13:07

You need rudder pedals to be able to do slips. If you are only using the joystick twistgrip you cannot apply the consistent and delicate application needed. What rudder pedals do you use, and do you use FSUIPC for calibration?

On the subject of ground effect: While this might not be a forum for complex aerodynamic discussions, I can assure you that ground effect is NOT a product of lift. Refer to:
http://www.se-technology.com/wig/index.php
which discusses what ground effect is - it is a DRAG factor, not a LIFT factor. When an aircraft wing is in ground effect (IGE) there is a reduction in Induced Drag, NOT an increase in lift. Indeed, if you think logically, there couldn't be - lift is a function of wing shap, speed, angle of attack, and induced drag. In the `float` configuration IGE, speed is reducing or constant, angle of attack is constant and the wing shape is fixed. So the only thing that could cause the continued flight, or float, is a reduction in induced drag...

To go back to your DC-3: What pilots do is change another factor - the wing shape (raise the flaps a notch) - and this does affect the lift, and the aircraft sinks. It also explains why a low-wing aircraft is affected more than a high wing aircraft IGE for the same wing shape, area, airspeed and AOA. The LIFT is the same. it's the induced drag that is different.

Hope this helps, as if you are planning on taking to the skies for real you will need a good understanding of what these terms mean, and how they affect the flying abilities of aircraft.
Simon Evans

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Sebastian
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Post by Sebastian » 01 May 2007, 22:35

snave wrote:You need rudder pedals to be able to do slips. If you are only using the joystick twistgrip you cannot apply the consistent and delicate application needed. What rudder pedals do you use, and do you use FSUIPC for calibration?
Wrong! I am pretty good in flying with the stick, using the Z-axis for the rudder, the hat for viewing und the other hand for either the throttle-axis or for my little cat who likes to sleep on my flying arm during FS-sessions... :lol:

No, you really do not need extra rudder-pedals, I have some, but I like sitting on my sofa in front of my notebook with my flightstick and my cat. As I said, the Realairs perform greatly with this configuration. I also do not have FSUPIC registered as I don`t find it necessary for the kind of planes I am using. Rudder pedals certainly make it easier to apply delicate subtile doses of rudder inputs but this doesn`t make the difference between no forward-slipping and easy-to-do-forward-slipping, does it?

P.S.:
Interesting stuff about drag, lift, etc.., although I hate physics and mathematics, I am alway grateful to learn something about real flying ;-)
Greetings from the Ruhrgebiet, Germany

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snave
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Post by snave » 02 May 2007, 01:05

It is pointless continuing this if you have no rudder pedals on which to base your assessment. Without them, you cannot easily apply the control elements necessary to forward slip as you can't truly separate out the various controlling elements.

Use your rudder pedals, and we can continue this conversation.

The fact is aircraft have rudder pedals, not rotating sidesticks, and after a hundred years - and several experiments at alternatives - it is reasonable to assume that rudder pedals have proven their effectiveness and why they are needed. No flight sim enthusiast who has used rudder pedals would comment as you have...

It is that simple. And we have got to the heart of your original question - you don't have the controls to be able to successfully carry out the manouevre. It's not the aircraft, it is your computer. As I said.

Saitek have some nice pedals, as do CH Products.
Simon Evans

anders
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Re: Rudder output correct?

Post by anders » 08 Jan 2016, 18:05

Hallo all Safir-lovers !

The SAAB 91-rudder in FSX doesn't function at all ! When you turn left (without banking) the plane turns right ! Impossible to make correct crosswind-landings. When I learned flying many years ago , the instructor showed the "rudders secondary effect on the aircraft" , first he plane turns , then it banks in the same direction due to the outer wings higher lift , then the plane turns into a downward spiral .
This effect can be demonstrated in most FSX-planes (even addons) , but not with the Safir !


Best Sim-regards

Erik

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