Two pedal sets and one tiller ... what can be done for "soft" switching ?

[Pete Dowson]

Also I got mention about testing the flight controls after a/c moves off from a former B737NG Ryanair pilot, now flying the triple seven with Emirates.

Interesting as I am pretty sure it is Ryanair pilots my contact deals with! I'll pass on to him these conflicting reports! ;-)

Pete

[eudoniga]

Interesting, isn't it ?

I lately watched a VHS of a simmer friend, it was about a 737 old generation, and - being usually interested in the 737 procedures - I noticed the pilots checked the yokes and the rudders on their way to the runway ... and it was taped on video ... :mrgreen:

Obviously I can't tell you if anything "mechanical" changed from those a/Cs to the 737NG.

Will try to enquire more, it has become ... intriguing ! :cool:

As always, thanks for your dedication and neverending attitude about perfecting FSUIPC.

Rgds,

Eu

[Pete Dowson]

Interesting, isn't it ?

Even more intriguing now, actually. I think things must have changed somewhat. RyanAir now follow Boeing recommendations in this matter -- see the extract from their current checklist below, which is from the official Boeing one.

Additionally he explained "when you move the rudder pedals then the nose wheel will NOT steer if you keep the tiller in position, because the tiller is the only direct control for the nose wheel and can not be overridden by the rudder. So if you move the rudder then you will see on ground that as well the tiller will move magic to the nose wheel position because its actuator has a direct wiring connection to it (a bit more complicate but in a simple way seen). And that means if you move the rudder pedals you can just keep the tiller in its position to let the Nose wheel NOT steer."

This is actually relevant in the before-taxi scenario, i.e. while static, because of the possibility of the toeing gear still being connected, or, if not, scrubbing of the nose wheel tyres on the ground and the unwanted additonal wear this would cause.

So the problem in FS is that unless the creator of an add-on aircraft can do it (if it is possible), the nose wheel cnnot be held straight whilst the rudder is moved, so that part of the real thing cannot be executed. Additionally, I have had it confirmed that at all speeds less than 30 knots the rudder maximum deflection is 7%, which is about 10% or its normal max of 67%, so my original 10% minimum to 30 knots was correct.

Regards

Pete

===========================

My red highlighting

From actual Ryanair Checklist

3.11 Before Taxi Procedure – Pilot Flying <RYR>

Flight controls ...........................................................................................................Check

Make slow and deliberate inputs, one direction at a time.

Move the control wheel and the control column to full travel in both directions and

verify:

• freedom of movement

• that the controls return to center

Hold the nose wheel steering wheel during the rudder check to prevent nose wheel

movement.

Move the rudder pedals to full travel in both directions and verify:

• freedom of movement

• that the rudder pedals return to center

[eudoniga]

I see.

With no big search, I had found a passage from a book I bougth, Mike Ray's B737 Checkride procedures manual, deals with flight controls among the "DURING TAXI" stuff (p. 147), saying "... both pilots should 'get on the controls' while the Captain moves them gently, through their full range of movement." So - maybe - one thing is what airlines suggest (or command) to their crews for a variety of reasons, including ... the sake of tyres (which is good), and another thing is what can materially be done with the a/c (which is neither necessarily bad to the machine nor dangerous for people).

Good for me, I can write - and follow - my own company checklist ! :ph34r:

As for the manoeuvering angles, I found useful info (in the same sense you were told) from Bill Bulfer's 737 Flight Deck Companion (p. 130), confirming that tiller's full travel is 78° and overrides pedal input, whilst pedals' full travel (on the ground) is 7°. A similar contribution taken from an airliners.net forum thread, also about some mechanical details: "... hydraulic power is used as the "muscle" for nosewheel steering, with commanded inputs from the tiller or rudder pedals either mechanically (cable) or "by wire". The linking/mixing of the tiller/rudder controls to the hydraulic metering valve (which ports pressure to either left or right actuators) is such that they input with different ratios: ballpark figures here as A/C differ;... full tiller input will usually steer the nosewheel approx 78 degrees from the centerline - or - Full rudder input will move the nosewheels somewhere around 7 to 8 degrees from centerline".

But - as you said - FS is another deal ! :roll:

Thanks for helping, I will post the final impressions about your new improvements, which may well become the new "state of the art" in this field ... ;)

Brgds,

Eugenio.

[Pete Dowson]

Thanks for helping, I will post the final impressions about your new improvements, which may well become the new "state of the art" in this field ... ;)

I've changed them slightly again, though the settings you will want to use will be the same. In 3.999y4 and 4.859m, which I'll upload later after a little more testing, the MaxSteerSpeed parameter has all these facilities:

8 The facility to 'blend' FSUIPC's steering tiller control into rudder control as speed whilst on the ground increases has been improved for airliners with a set of facilities to restrict the rudder effect in different groundspeed ranges.

The simplest of these facilities keeps the rudder at 10% of its input until half way to the full threshold speed, then increase linearly to 100% This is intended to make reasonably easy to check the rudder pedals whilst taxiing without causing bad swerves, and also allows some use of rudder even at very slow speeds at the end of the landing ground roll. The value of 10% minimum comes from the 737NG where at taxi speeds the rudder deflection is a maximum of 7 degrees compared with 67 degrees fully.

To make FSUIPC do this blending instead of the normal 0-100% linear method simply change the

MaxSteerSpeed

parameter in the relevant [JoystickCalibration] section of the INI file to a negative value, eg -60 for the default 60 knot threshold.

A more complex specification can be provided which allows the user even more scope. The

MaxSteerSpeed

parameter can be given as

MaxSteerSpeed = Qn1,n2,n3,n4

where n1 to n4 are numbers used as follows:

• If n1 is not zero, then rudder effect is 0% (ie eliminated) until a groundspeed of n1 knots. Then the effect rises linearly from 0% at n1 knots to 10% at n2 knots.
  

• If n1 is zero, then rudder effect is 10% until the groundspeed reaches n2 knots. n2 is not allowed to be zero.
  
• If n3 is not zero, then rudder effect rises linearly from 10% at n2 knots to 30% at n3 knots, then linearly again from 30% at n3 knots to 100% at n4 knots.
  
• If n3 is zero, then rudder effect rises linearly from 10% at n2 knots to 100% at n4 knots. n4 is not allowed to be zero.
  

Note that apart from the option for n1 and n3 to be zero, n4 > n3 > n2 > n1. You should see that the option:

MaxSteerSpeed=-60

is in fact the same as specifying

MaxSteerSpeed=Q0,30,0,60

There is one shortcut.

MaxSteerSpeed=Q

is the same as specifying

MaxSteerSpeed=Q10,20,30,60

Note that both tiller and rudder need to be assigned in FSUIPC by the "direct to FSUIPC calibration" method, and both be properly calibrated, for any blending to be active in any case.

Have fun!

Pete