why should the stick be held backward during taxi? - Page 3 - ED Forums
 


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Old 01-12-2018, 05:17 PM   #21
Captain Orso
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Aside from keeping the tail down in general during taxiing, the more weight on the tail wheel the better it stayed straight:

Full Thread here: Engine Boost Control + Ground Handling

Excerpt:
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Originally Posted by NightRush View Post
Ground Handling

Tail Wheel Castering
Tail wheel, currently in game the aircraft's tail wheel behaves like a shopping cart; in that is has reduced or no centering force to bring the tail-wheel aligned under the fuselage centerline. So what is happening in sim, the aircrafts tail refuses to stay behind the main wheels even when centered, and no external force is added (Power applications or wind)

In real life, while it is true the tail wheel is free-castering that is not the full story. The tailwheel design has a built in weight and geometry centering. I will do my best to describe it here with images and words.

The first is the weight/geometry holding the tailwheel centered. The axis that the tail wheel rotates through horizontally is on a tilted plane. Unlike say a shopping cart where the wheel rotates in a plane parallel with the ground, the wheel has a high point and a low point in its travel.

What this means is for the tail wheel to move from its centered position, there needs to be enough side load to compress the tail wheel oleo strut to effectively raise the tail. As the contact patch of the tail wheel rotates to say 180 degrees to centreline, the angled plane mean the wheel is in a "lower" position that when it started from its trail position. (See next picture) Please note that the image is showing the tail wheel oleo uncompressed, ie no weight on the wheel (and also those sweet sweet photoshop skills)

This means the tail wheel has oleo compression force centering the tailwheel once there is forward movement. Ontop of which any elevator and prop blast forces needed to be added to this as well.



The other centering force thats acting on the tail wheel is simply the wheels axis is behind the yawing axis/horizontal plane. This trail force naturally makes the tail wheel want to be behind the rotating (castering) axis due to friction.

What this means in practice with the above two scenarios, is as the aircraft starts rolling forward the tail wheel naturally wants to allign itself with the center line of the fueslage. However in game, we currently have a tailwheel that wonders around aimlessly. It however does feel like it has some centering force as ground speed increases and elevator loads hold the tail wheel to the ground. But its at the slow speeds where the tail wheel should have a little bit more natural centering force. Once the aircraft is at a walking pace, brakes should only be required to turn the aircraft, not keep it straight (in a zero wind scenario)

I'm still wondering if ED actually modeled this.
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Old 01-12-2018, 09:10 PM   #22
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Good explanation, Orso, and it makes sense (as much sense as British engineering ever makes sense).

Would also request devs to confirm it actually is modeled.
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Old 01-17-2018, 12:04 PM   #23
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I originally modded the FM\FMOptions.lua file for the spit to alter the friction of the tail wheel castor via this
tailGearAxleFricM0f = 35.0 -- Original 11.0


...amongst other things.. which improved it for me at least.
Also these, the top one making it less like a power ball bounce:-
tailGearSpringForceFactor = 11000000 .-- Original 17000000
tailGearStaticForce = 6000 -- Original 3000

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Old 01-17-2018, 01:48 PM   #24
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I have the Crosswind pedals too. I use the either pedal applies brakes method because it is analogue (incremental control) whereas the joystick lever is digital (Fully on or off only).

The pedals can be awkward until you get used to them, but they give far more subtle and precise control than an on off button can.

I'm looking forward to getting hold of a VKB joystick with the analogue lever too of course.
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Old 01-19-2018, 11:34 AM   #25
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Quote:
Originally Posted by NeilWillis View Post
I have the Crosswind pedals too. I use the either pedal applies brakes method because it is analogue (incremental control) whereas the joystick lever is digital (Fully on or off only).

The pedals can be awkward until you get used to them, but they give far more subtle and precise control than an on off button can.

I'm looking forward to getting hold of a VKB joystick with the analogue lever too of course.
I use the analogue lever on my VPC stick , works very well. I used to have assigned to both Crosswind pedals but like the lever better.
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Old 01-19-2018, 06:17 PM   #26
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Using analog brake lever on my MCG, it's a work in progress for me but it is easier to use
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Old 01-20-2018, 06:13 AM   #27
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I use my home made brake lever. It really improved taxiing in the russian aircraft, and the Spit.
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