Engine Failure Behavior (question for Jan)

[tango4]

Hi IXEG team,

My question is especially directed to Jan. 

First of all all what I will say below is with X-Plane 11.05 and IXEG 1.2

Here is my issue: I want to practice some engine failures at V1.

I am using default XPlane failure (engine failure at a specific speed which I arm for V1). I tried it at different weights.

My problem is that I have the feeling that the initial reaction of the aircraft is way too abrupt and rudder not efficient enough. I don't have enough rudder authority to counter it, and for example if I fail Eng1 the aircraft veers to the left EXTREMELY fast and I can't even stay on the runway almost every time. (Sorry I can't be more precise). It's as if the engine goes from full power to zero power instantaneously

Now, I don't pretend to be an awesome pilot of course ! The reason I have the feeling there is something strange is that I am consistently able to counter such a failure on other sims known for their quality flight models like Aerowinx PSX and Majestic Q400.

Jan, I'd be interested to get your take on it or point me to a specific technique for this aircraft.

All the best.

 

Charles MOULIN

[Litjan]

Hi Charles,

make sure that your reaction is correct in dependence to V1. If your engine fails below V1, you must immediately retard the live engine to idle. Speeds below V1 are also below Vmcg (minimum control ground) most of the time - at this speed it is impossible to keep the aircraft going straight with one engine at full power.

If you are above V1, you can continue - but you must make sure to stay at that speed or higher to have enough authority on the ground to keep going straight. In the air you must be abvoe V2 (as this ensures speed > Vmca) so you can control the yaw with rudder and some bank.

If you have additional crosswind and the runway is wet or even icy, you may be unable to control direction even at V1 - but this condition is not taken into account when doing the takeoff calculation.

I agree that the onset of yaw is pretty fast in X-Plane - compounded by the fact that you have no "yaw sensation" to alert you - in the real plane kicking the correct rudder is almost instantaneous, almost like moving the handlebars when riding a bike. Like a reflex.

Cheers, Jan

 

[tango4]

Well, that's what I call fast support !

Thanks a lot for your help.

Just a small confirmation: as I do not know a good take off performance calculator for that plane, I usually use FMC computed V Speeds. I guess the V1 it provides should be OK as long as I am not limited by the runway length or obstacle clearances. Could you confirm that assumption is right with regards to that specific issue ?

What I might do is  trigger the engine failure 2 or 3 knots above V1 just to be on the safe side regarding Vmcg.

 

Charles

[Morten]

Also note that the XP11 tyre/friction model is still under construction by Laminar and might affect this.  We will review this after XP v 11.1 is out

[Litjan]

1 hour ago, tango4 said:

Well, that's what I call fast support !

Thanks a lot for your help.

Just a small confirmation: as I do not know a good take off performance calculator for that plane, I usually use FMC computed V Speeds. I guess the V1 it provides should be OK as long as I am not limited by the runway length or obstacle clearances. Could you confirm that assumption is right with regards to that specific issue ?

What I might do is  trigger the engine failure 2 or 3 knots above V1 just to be on the safe side regarding Vmcg.

 

Charles

That is correct - the calculated V1 should be safe. Vmcg for the 737 is usually not higher than ca.115 kts.

Of course a pilot needs to be able to handle an engine failure at lower speeds, too - but you need to be extremely fast to avoid running off the runway if an engine fails at low speeds (20-50 kts), especially on a wet runway. Then again, running into the grass at that speed is not catastrophic...

Jan

 

[tango4]

Thanks a lot to both of you.

It may indeed have something to do with tyre friction and the fact that engine failure seems a bit sudden in XPLANE.

Because the issue I have is really with the initial reaction. Once airborne the 737 is a bit tricky with an engine out especially at high gross weight, but it does seem realistic (here I have difficulties also, but because of my lack of skills !).

Anyway, I really appreciate your help.

 

Charles