Tail Dragger turns too slow on the ground

[wilderobb]

How can I get my tail dragger to turn a little better on the ground? It will turn, but it takes forever to get lined up on the runway. Any Help, Thanks a Million

[Hagar]

Depends on the aircraft. Some taildraggers have steerable tailwheels but many of them are fully castoring. In this case the steering on the ground is controlled by the rudder on single-engined aircraft, sometimes assisted by differential brakes. This can also be controlled with the throttles on multi-engined types. To be effective the steering is done with short bursts of throttle & large rudder movements. Unless there's a strong tailwind make sure you hold the stick hard back at all times to keep the tail down while taxying.

That's how it's done in real life & this is simulated in FS to some extent. You can cheat by editing the tailwheel parameters in the [contact_points] section of Aircraft.cfg. The tailwheel will usually be point.0 but I don't have FS installed right now & can't remember the exact parameter that affects the steering angle. You can check this from the comments in any default Aircraft.cfg. The value can be anything between 0.00 (fixed) & 180.00 (fully castoring). I find that a steering angle of 60.00 or thereabouts is about right.

Also remember that some aircraft will have a tailwheel lock to keep it straight on take off. This has to be disabled before steering on the ground.

[RollerBall]

Righty ho - here's my standard reply that I keep on file...

The main problem with tail draggers is that designers, in an attempt to be 'realistic' make the tail wheel castor through 360 deg.

This in fact is totally unrealistic for the sim which cannot handle it. Here's a snippet from the contact points section of a DC3 taken from my folder.

[contact_points]
point.0=1.000, -34.390, 0.000, -1.611, 1574.000, 0.000, 0.995, 90.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000
point.1=1.000, 2.630...etc

The 90 in red is the steering angle. Some designers make this figure 180 for tail draggers and the plane is virtually uncontrollable on the ground.

Even 90 is quite a big figure. If you set it to 60 or 70 the plane will still turn very well and will be nicely steerable.

Unfortunately many designers, even some quite big ones, have still not grasped that the MS Flight Simulator program engine is far from perfect. This applies to almost every parameter IMO. You can't plug in 'real life' numbers and get something that performs like the real thing. Maybe in X-Plane but not in this sim.

And I'm speaking as someone who has modded dozens and dozens of FDEs.

BTW

You can edit the aircraft.cfg file using a text editior such as Wordpad or Notepad.

[wilderobb]

Im not quite sure of what to change so heres my contact points:[contact_points]

point.0=1, -20.6, 0.0, -1.9, 1574.8, 0, 0.5, 75, 0.5, 2.5, .5, 0, 0, 0

point.1=1,   3.9, -5., -6.7, 1574.8, 1, 3.2, 0, 0.5, 2.5, .5, 0, 0, 0

point.2=1,   3.9,  5., -6.7, 1574.8, 2, 3.2, 0, 0.5, 2.5, .5, 0, 0, 0

point.3=2 ,-4.1,-14.8, 3.5, 1574.8,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,5.0,0.0,0.0
point.4=2, -4.1, 14.8, 3.5, 1574.8,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,6.0,0.0,0.0
point.5=2,-16.3,  0.0,-2.4, 1574.8,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,9.0,0.0,0.0
point.6=2,  5.5,  0.0,-1.8, 1574.8,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,4.0,0.0,0.0
static_pitch=11
static_cg_height=5.4
gear_system_type=0

Thanks for the replys

[RollerBall]

hmmmm... yours already has a reasonable steering angle. The problem lies elsewhere. What aircraft is it? Can you post a copy of the Moments of Inertia section in the cfg file because it's probably there.
That's the bit that looks like this....

empty_weight = 3912
empty_weight_roll_MOI  = 8892
empty_weight_pitch_MOI  = 3761
empty_weight_yaw_MOI  = 10671

[Nav]

You'll find that a burst of throttle acts on the rudder (particularly with single-engine types) and helps the turn a lot. You have to be careful not to overdo it though!

Some types (like the DC3 and the DH88 Comet) need a burst of throttle-and-brakes applied to start the turn. But it's important to use opposite rudder in good time to cancel the turn, if you don't it will just go on turning.

Best to keep the tailwheel lock on when taxiing straight, release it to turn. Forget the keystroke required, see 'Kneeboard/Keys').  

[Jakemaster]

yeah, what plane is it?  also, try hitting SHIFT+G to unlock the tailwheel

[MattNW]

Also make sure you don't have your tail wheel locked. If it seems to turn slow then press "Shift+W" and see if that doesn't improve handling. Be sure however to hit "Shift+W' again after you are lined up and ready to take off or you might go for an unexpected tour off the runway.  ;D

[TacitBlue]

I thought Shift+W was the water rudder.
I usually use a lot of differential brake when taxiing tail-draggers. Seems to work for me.

[Hagar]

I thought Shift+W was the water rudder.
I usually use a lot of differential brake when taxiing tail-draggers. Seems to work for me.

This is the default command
Tailwheel Lock On/Off SHIFT+G

Of course, you can reassign it to any spare key you wish.

It will depend on the type of aircraft but it's worth remembering that many taildraggers were intended to operate from grass fields with no defined runways. They usually take off & land directly into wind & can be very difficult to control crosswind or on the ground in windy conditions. I taxyed single-engined taildraggers like the Tiger Moth & Auster every working day for two years & it was very often easier to turn the wrong way & go round in almost a complete circle to point in the direction you wished to go. We would never taxy a biplane like the Tiger Moth in winds over 20 knots without a man on the wing, let alone allow anyone to fly them. At places like Old Warden where they display vintage taildraggers they never taxy those valuable aircraft without a man on each wing to help with manoeuvring. It's difficult to see over the nose of most taildraggers so you have to constantly weave from side to side to see where you're going.

PS. This is what can happen all too easily when landing slightly out of wind in gusty conditions. The pilot is Andy Sephton, highly experienced chief pilot of the Shuttleworth Collection at Old Warden so even the best can be caught out. The shot was taken by CraigL who was standing next to me at the time.

[wilderobb]

Yes Rollerball, the aircraft is the Douglas World Cruiser, a fantastic aircraft and very well done by Dennis Simanaitis. The part of the file you asked for is:

empty_weight=4300.0
empty_weight_roll_MOI=30000.0
empty_weight_pitch_MOI=60000.0
empty_weight_yaw_MOI=90000.0
empty_weight_coupled_MOI=0.0
max_gross_weight=6915.0

I may just have to have the locals turn me around.
Thanks again to all for the help, Wildie.

[RollerBall]

Woo

those figures are much too high for an aircraft like this but having now tried it, that's been done to disguise what I'm afraid is IMO a rather poor air file.

As soon as you reduce them the plane starts dancing about on the ground with the engine at idle with sparks jumping up off the rear scrape point. This is often symptomatic of a contact points problem. The class for point 0 (the first entry on that line) needs to be changed from 1 to 3 as it's a skid but that doesn't help much.

I've messed around a bit but I'm afraid I could never get to love this one so I'm leaving it for now - probably for good actually   :-/

[wilderobb]

Ok, Thanks anyway. I too got the same reaction when I changed things too. I'l leave it as it is I guess.

[RollerBall]

I dunno - I'm a sucker for a challenge. I've almost finished a completely new air and cfg file for the wheeled version which solves the turning problem and gives more or less the right cruise performance. I'm just sorting out the trim.

You'll have to PM me your email and I'll send the files to you to test.

[RollerBall]

OK robb gottit - now delete your last post or remove the email because otherwise that's how you start getting tons of spam and stuff  ;)