Take Off N1 Thrust question

[Bob Reed]

Thank you for that Themis! Looks like I need to dig out a couple of my manuals....

[Trevor Hale]

Interesting. Actually the Dassault Falcon has a System A and System B braking system. As you hold pressure on the toe brakes and advance the throttles there is a point in which the system itself realized that system A cannot sustain the braking pressure, you feel a little jolt as system a releases and system B engages, Feels like your feet slip off the peddles and when you release the toe brakes the aircraft thunders down the runway!

Amazing feeling.. Like you cannot believe...

[Tomlin]

Trevor, you've actually got to take off in a Falcon jet? Wow, that must have been really awesome. I would love to do the same in a LJ45. Actually, to be honest, I love flying in almost any aircraft. But, the one youre building is such a bonus to the experience!

[Trevor Hale]

Trevor, you've actually got to take off in a Falcon jet? Wow, that must have been really awesome. I would love to do the same in a LJ45. Actually, to be honest, I love flying in almost any aircraft. But, the one youre building is such a bonus to the experience!

Yes, I get to ride in them occasionally. When I travel for Business.

[Ray Proudfoot]

The parking brake is merely a physical lock on the brake pressure in any case, so whether you use foot pressure or the parking brake lever is rather irrelevant. If you have your pmSystems programmed correctly you'd find you have to depress the toe brakes to create the brake pressure then pull the PB handle to lock the pressure on. In that sense it is rather similar to the way the parking brakes operate in a humble Cessna.

Regards

Pete

Hi Pete,

Yes, I remember your system where it was necessary to push both pedals to apply the p/b. Perhaps on my next visit we can try the auto-throttle on t/off instead of manual throttle control. I bet that surprises you.

Cheers.

[Ray Proudfoot]

Hi Themis,

Thanks very much for that info. If I understand the instructions correctly during taxiing on the active N1 should be around 40.

Once lined up I switch A/T on and manually advance the throttles to N1 and then engage THR (TO/GA). The a/p will then make adjustments to the throttles to ensure they don't exceed N1.

You haven't mentioned the brakes. Are they touched at all once the aircraft is lined up and before the throttles are advanced to N1?

Thanks.

[themis]

Hello Ray,

When you taxi you try to not speed up over 20knots Ground Speed. If you are close to manouvering areas (near airports buildings) you try to be at 10 knots . In real life I've seen taxi speed up to 40 knots when the Tower is not seeing you..

The N1 value on taxi is not something to be considered of. Depends on your weight. The 737 doesn't need huge amounts of thrust to taxi. Just an initial push...and it rolls and very easily a bit over idle.

When you reach holding point if there is traffic you can use the parking brake to fully stop the aircraft and not applying toe brakes as you waiting for clearance. In critical phases (holding point, line up) if you think that there is gonna be a delay before the clearance arrive, you can use parking brakes for safety that the aircraft would not "slip" on the runway. After you get the clearance and release the brakes you advance the throttles to taxi for line up and *when you feel comfotable* you advance the Throttles up to 40% N1 waiting for the engines to stabilize... then TOGA... autothrottle does the rest.

When you get used to the procedure you can advance the throttle to 40% starting from the holding point and not after lining up as the real experienced pilots do...

In short runways I'll use brakes at the stabilization period to gain some meters.

Themis

[Peter Dowson]

Is it possible to program this even with using the Parking Brake release when toe brakes are applied? I have not done too much with PMSystems yet.. Just looking at starting.

Provided you program your parking brake lever to operate the pmSystems switch, not the FS one directly, the option code in the current 737 pmSystems logics handle the checking to see if you are pressing the pedals enough before engaging. I'm not so sure they currently offer automatic release on pushing the toe brakes, if that's what you mean, but that should be easy enough -- I haven't got that in operation here.

Of course the braking should, in any case, be dependent upon having sufficient brake pressure, but I've no dial for this in my cockpit so I've not got that implemented. For this to be truly correct the toe brakes should also be routed via pmSystems, which isn't so easy considering they are normally axes not buttons. Really I would need to add axis-disconnection facilities in FSUIPC, similar to those for other axes (for "fly-by-wire"), where the input axis value is supplied in a different offset but not applied to the real FS controls. Something else for my list I suppose.

Regards

Pete

[Peter Dowson]

Yes, I remember your system where it was necessary to push both pedals to apply the p/b. Perhaps on my next visit we can try the auto-throttle on t/off instead of manual throttle control. I bet that surprises you.

Not half! You have always been so steadfast inn refusing to use TO/GA!

Pete

[Thomas Richter]

For this to be truly correct the toe brakes should also be routed via pmSystems, which isn't so easy considering they are normally axes not buttons. Really I would need to add axis-disconnection facilities in FSUIPC, similar to those for other axes (for "fly-by-wire"), where the input axis value is supplied in a different offset but not applied to the real FS controls. Something else for my list I suppose.

Regards

Pete

Hi Pete

Oh ja. Hopefully it is near the top of the list (Vers. 3.xx + 4.xx)