Single Engine Taxi - Won't Taxi

[RedSqn Commander]

With either engine shutdown it's not possible to taxi at all.

[Terry Dactil]

Since you can't lock or steer the tail wheel, what else can you expect?

On the ground, there is no way you can turn towards the good engine unless you are already moving and can use differential brakes.

However to get moving, you can only start move in a circle into the dead engine. There is absolutely no way to turn towards the good engine as the thrust and braking are in the same line.

I flew DC-3s many years ago and soon learned that when you land with only one engine the flight ends where you stop if the tail wheel is unlocked.

[RedSqn Commander]

I totally get what your saying but I just find it hard to believe there wouldn't be enough (less asymmetric) thrust to provide movement sufficient enough to allow differential braking to perform some form of taxi... even though it won't be pretty. 

 

With no RW twin or tail dragger experience I have to accept what your saying.

 

I can't find any material to suggest it will/has taxied on one engine, but I also can't find anything which says it can't or it must be parked on landing, even in authentic pilots notes.

 

Interesting never the less.

[Yo-Yo]

On 9/21/2021 at 1:54 AM, Terry Dactil said:

Since you can't lock or steer the tail wheel, what else can you expect?

On the ground, there is no way you can turn towards the good engine unless you are already moving and can use differential brakes.

However to get moving, you can only start move in a circle into the dead engine. There is absolutely no way to turn towards the good engine as the thrust and braking are in the same line.

I flew DC-3s many years ago and soon learned that when you land with only one engine the flight ends where you stop if the tail wheel is unlocked.

It's just because of cruel physics... If you have asymmetric force (thrust) applied it creates a moment. This moment can be counteracted with a pure moment (if you, for example,  start to spool up a giant flywheel at the vertical axis :D) or with a decentered force - a sideforce of the fixed tailwheel you do not have actually.  The braking force of a tire right under the engine could eliminate this moment but the only small detail spoils all - the braking force must be exactly equal to the thrust eliminating it as well. 

[Hamm66]

I disagree. I was able to taxi back with the right engine alone from standing still with the brakes on after a left engine failure. I was able (with difficulty) to taxi back to the ramp and request a 'repair engine' from the ground crew and continue the mission.

 

What I did was; leave the parking brake on and increase power on the working engine (stick pulled all the way back), full rudder before releasing the brake and then, once rolling, tap the brakes whilst maintaining full rudder to try to run straight. It was hard to do (for me at least).

[TheCrysinator]

Since you can't lock or steer the tail wheel, what else can you expect?
On the ground, there is no way you can turn towards the good engine unless you are already moving and can use differential brakes.
However to get moving, you can only start move in a circle into the dead engine. There is absolutely no way to turn towards the good engine as the thrust and braking are in the same line.
I flew DC-3s many years ago and soon learned that when you land with only one engine the flight ends where you stop if the tail wheel is unlocked.

Can you lock the tail wheel in the Mozzie? I experienced a similar outcome as you described when doing single engine landings and it's definitely something I don't want to repeat!

[Terry Dactil]

14 hours ago, TheCrysinator said:

Can you lock the tail wheel in the Mozzie?

No. No tail wheel lock. So once you have stopped the game is over.

This explanation might help ...

While you are moving any braking action gives you a force forward through the center of gravity due to inertia.

Take the remaining engine thrust into account then the resultant forward force will be shifted over a bit toward the operating engine but will still be pretty close to the aircraft center line

This means you can apply a braking force on either side of this forward force to produce a turning effect and steer the aircraft.

However, once stopper there is no inertia to use and resultant forward force is now on the engine thrust line.

Since this is over the wheel and brake there is no way to apply any braking force outboard of the engine to turn in that direction.

The only chance you have is if the tail wheel is locked straight and you can get moving again to get some  inertia or momentum to use again as above.

To really over analyze this you can take into account the P-factor offsetting the thrust line to the side of the descending prop blade.

If it is the left engine operating this will be slightly inboard of the engine, so it should be theoretically possible with the left brake to  generate a very small left turning force, but I don't expect ED to get down to this level of detail.

(Just tried that and it is true. I could only go in circles to the right).

 

PS.
This thread has brought back memories as I've been telling this from first hand experience with tailwheels.
Many years ago I was flying DC-3s in New Guinea and we had an engine failure and landed on a small remote airstrip.
The landing was not a problem, but we needed to get clear of the strip to allow another aircraft to land with the maintenance crew and spare parts for the repairs.
Turning around 180° at the end of the strip was easy, but now that the tail wheel was unlocked we could only go in circles.
Fortunately the local police had working gang nearby, so with them pushing on the rear fuselage and tail for steering and us using the good engine for moving, we "taxied" back along the strip to the parking bay.
That was great fun and entertainment for everyone.
Thanks for bring back the memory.

Edited September 23, 2021 by Terry Dactil
Memories

[grafspee]

21 hours ago, Hamm66 said:

I disagree. I was able to taxi back with the right engine alone from standing still with the brakes on after a left engine failure. I was able (with difficulty) to taxi back to the ramp and request a 'repair engine' from the ground crew and continue the mission.

 

What I did was; leave the parking brake on and increase power on the working engine (stick pulled all the way back), full rudder before releasing the brake and then, once rolling, tap the brakes whilst maintaining full rudder to try to run straight. It was hard to do (for me at least).

Taxi back mossie has reverse thrust ?

[Terry Dactil]

12 hours ago, grafspee said:

I was able to taxi back with the right engine alone from standing still

I would be interested to know if you could confirm that you had no assistance from any external turning force helping you like not being on a level surface or with any crosswind.

If you could repeat the exercise in the opposite direction that would be significant.

[grafspee]

6 hours ago, Terry Dactil said:

I would be interested to know if you could confirm that you had no assistance from any external turning force helping you like not being on a level surface or with any crosswind.

If you could repeat the exercise in the opposite direction that would be significant.

How did you do that? I did not type that sentence,  i was quoting someone else but it is labeled that i did type it.

I type only one sentence in this threat "Taxi back mossie has reverse thrust" 

[Terry Dactil]

Sorry. I should have cut the quote from the original post a few posts higher. I thought that quoting a quote would be tagger  with the original and did not bother to check .

Anyway, I think most people can work out what I was referring to,  just as most people also know the difference between going back and going backwards.

[Hamm66]

No, I did not taxi backwards. Ha Ha! It is entirely possible that this was a fluke. My left engine was overheating everytime I got to the runway before the last update - it does not overheat now. I did notice that although it was smoking and running rough it did not register as a failure when I ended the mission.

 

On the occasion I mention above I thought I had shut down the left engine and I was sure I was at a full stop at the seaward end of Manston airfield. Due to the bug I thought my engine was overheating as it was smoking and rough. I stopped the left engine but I still had both engines selected as I increased the throttle input and began to taxi. So there may have been a difference between the physics and the graphics.

 

Either way, hard to test as the new update has changed the conditions. Left engine works fine now....

 

Edit: I went back and attempted to replicate the situation (albeit with the new update) and, although I was able to get a bit of forward momentum it was not enough to actually taxi anywhere - I just wound up going in large circles until my right engine burned out. Must have been a fluke before.

Edited September 24, 2021 by Hamm66
more information

[Terry Dactil]

Thanks for that info.

I tried some exercises at Manston as it looked to be the most level surface available with plenty of clear space.

I was never able to successfully taxy on one engine from a standing start.

The best result I had was when I had a 15 kt crosswind. This almost worked, and I managed some progress down the runway.

However, each brake release/apply cycle cost a few degrees of heading that could not be recovered, so I eventually ran off the side of the runway.

ED have got this right and it matches what I have experienced in real life.