Engine thrust for taxi 737?

[chksix]

I did a search but could not find this question asked before.

How much thrust do you use to get the plane rolling after pushback and what power setting will keep the plane rolling at a constant speed during taxy?

Also, how much tyre drag is generated by the nosewheel in tight turns? i.e. does the 737 slow down a lot when turning into the gate?

I'm asking for desktop simulation realism reasons....

(Is it spelled taxi or taxy btw )

[yachtno1]

Taxi and Taxying . A light 737 will move under idle thrust. Not sure about cornering though !

[FlightDetent]

Originally Posted by chksix

I did a search but could not find this question asked before.
How much thrust do you use to get the plane rolling after pushback and what power setting will keep the plane rolling at a constant speed during taxy?
Also, how much tyre drag is generated by the nosewheel in tight turns? i.e. does the 737 slow down a lot when turning into the gate?
I'm asking for desktop simulation realism reasons....
(Is it spelled taxi or taxy btw )

1. Impossible to tell (unless you're the designer). It is very much weight dependent. Tiny slope which there is always, makes a lot of difference. Once moving, it may even keep accelerating on idle over even and level ground, Weight again.

2. Dtto. It seems to slow down a little (this must be the case - physics)

3. Always tought this was a uk/us thing. Tire, Tyre.

[chksix]

Thanks!

It seems my model is behaving correctly then

[Luckyguy]

It is recommended that a maximum of 35% N1 is used to start the aircraft moving and after this sufficient power should be maintained to keep the aircraft moving at a constant steady speed. Most operators use a maximum of 25 or 30 kts g/speed. Light weight aircraft, as previously stated perhpas need no increase in power to start moving: heavy aircraft may need 35% ! I have used as much as 45% to get a heavy aircraft moving up a slope !

[XPMorten]

1. I'm afraid not, X-Plane's brakeaway friction is too high.
You can't design your way around that.

M

[Rotates Lowly]

A B732 will in most cases start rolling without any thrust application, but the B733/4 need help, and I agree with the 35% to 40% on the latter two types mentioned. For the B732 a maximum of 1.1 EPR is recommended for passenger comfort. By the way, I operate these types out of hot & high airfields, although at high weights these figures are applicable at sea level as well.

[chksix]

The ground friction and tyre model in Xplane is indeed flawed and the interface in PlaneMaker does not provide enough options to tweak it.


Very light rolling resistance is making the plane behave somewhat closer to reality.

[Tee Emm]

For the B732 a maximum of 1.1 EPR is recommended for passenger comfort.

.

1.1 for pax comfort? For taxiing? They really must get upset when you apply take off thrust. Doesn't make sense...

[I-2021]

Pax confort is not really a factor at that stage. Jet blast is a factor... the FCTM gives guidelines on how to taxi and there are not many ways to do it.

[A37575]

It is recommended that a maximum of 35% N1 is used to start the aircraft moving

Interesting figure. Request the reference page in the Boeing published FCOM or FCTM for this figure as I could not locate it anywhere.

[barit1]

The 35% recommendation may be a CFMI request to minimize risk of FOD & erosion. Running static generally causes an inlet vortex to form ahead of the engine, which can pick up trash off the ramp. Once you're rolling the vortex blows away; using the least-possible breakaway thrust is good practice to preserve your engines.

[FlightDetent]

Well then. But what about the official guidance, numbers in FCOM/FCTM. I do not recall any (more) but perhaps it is just because it is immposible to have any.

What is the (recommended) maximum for cross-bleed N1, that may give a hint.?