Free Tail Wheel Rotation during Taxi - ED Forums
 


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Old 01-21-2018, 09:07 AM   #1
Weegie
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Default Free Tail Wheel Rotation during Taxi

Ok I'm ready for a bunch of sarcasm and general put downs

My question is why when the tail wheel in the Dora is unlocked does the aircraft swing so unpredictably and abruptly compared with the Spit.

I have no facts to bring to this argument but surely the Spitfire is more akin to a motorcycle with the main gear wheels being so close together, the Dora more like a trike, so the Dora would be the more predictable of the 2 to taxi with an unlocked tail wheel.

I've spent a lot of time in the Spit and have now been refreshing myself in the Dora and I just find that it seems to swing more violently than the Spit and is a lot less predictable/controllable.

When swinging one way and wishing to go the other and trailing the opposite brake, nothing usually much happens then BANG it starts to swing violently the other way......its like the tail wheel is stuck then suddenly frees itself with a vengeance.

The Spit isn't easy but providing it's caught early it's behavior is quite predictable. I just cannot do the same in the Dora and waddle down taxiway like a Penguin until I get stick back

Perhaps my technique is all wrong if so I'd love to be enlightened

Last edited by Weegie; 01-21-2018 at 10:45 AM.
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Old 01-21-2018, 02:57 PM   #2
probad
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comparisons to a bicycle or trike cant really be made since the tailwheel is freecastoring, so theres no force against lateral movement either way. however in brake-turn scenarios the width of the undercarriage on the dora serves to make it much more sensitive, as the movement arm from the acting force to the pivot point is so much longer.

the dora also has an absurdly powerful engine for the size of the plane and it should be no surprise that even what feels like minor movements of the throttle will lead to strong torque swings on the ground -- most people are far too cavalier with how fast they taxi anyways and if you taxi at recommended rpm settings (aka slowly and not going for that instantaneous acceleration) the dora is quite manageable.

snaking isnt exactly "bad" as you see irl warbird pilots snake down the taxiway for visibility, especially important for aircraft with such long noses.
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Old 01-21-2018, 03:18 PM   #3
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Thanks probad I hear the arguments and agree.

I am very gentle usually I never exceed 1200rpm most of the time under 1000 and when releasing the stick to free castor the tail wheel I'm at idle & not going much over walking speed on release

I don't think it's torque swing as I'm at or close to idle and not changing throttle settings (most of the time)

To me it's more like the tailwheel is stuck one way around then snaps and castors the other.

Maybe that's the way the real bird is but it's a helluva handful for a sausage fingered virtual pilot like myself
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Old 01-21-2018, 03:32 PM   #4
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not sure how strong and "extraordinary" your issue is then, a video or replay might help

unrelated, manual recommends not dropping rpm below 1000.
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Old 01-21-2018, 04:12 PM   #5
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You can find a brilliant 3-parts essay on our forum about taildraggers with brilliant explanation of unstable nature of their ground behavior. The possible difference between Spitfire and Dora can be either in the greater distance between main gear and CG Dora has or in the fact that you begin to counteract the instability from the start for Spit anticipating it.
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Old 01-21-2018, 06:15 PM   #6
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Quote:
Originally Posted by Yo-Yo View Post
You can find a brilliant 3-parts essay on our forum about taildraggers with brilliant explanation of unstable nature of their ground behavior. The possible difference between Spitfire and Dora can be either in the greater distance between main gear and CG Dora has or in the fact that you begin to counteract the instability from the start for Spit anticipating it.
Thanks Yo-Yo

Yes I have them & I'll need to re-read all 3 again.

It's aircraft related, I'm pretty sure but I don't know why the Dora sometimes behaves the way it does, it doesn't seem to occur every time.

I don't doubt the model I just find it a bit odd and counter intuitive, but lots of things are I suppose...................counter-steering was another one (not aircraft related)
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Old 01-23-2018, 12:17 AM   #7
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It might not have any relation, but don't forget that the Center of Gravity (CG), is further forward on the Dora than the Spit. That could affect the movement of the tailwheel due to more weight on the tailwheel.
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