Faster Throttle movement on Takeoff

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Tim737800
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Faster Throttle movement on Takeoff

Post by Tim737800 »

Hello Guys,
Im have a new Motorized throttle for a few days. It’s awesome to watch the levers move.
But I discovered, that the movement of the throttles after pressing TOGA on the Takeoff-run is way to slow.
I often reach 90-100 Knots before the engine takeoff power is set. In real life they take approx 1-2,5 sek to reach their power setting.

Would be awesome since taking off with high weight or on short runways is sometimes pretty close 😅😅


Thanks for the help

Cheers from rainy Germany
Tim
Building a Full size b737 Cockpit with galley and cabin inside of Ex Boeing 737-500 VQ-BAE
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Egyptair
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Re: Faster Throttle movement on Takeoff

Post by Egyptair »

+1

Ahmed
Sudden81
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Re: Faster Throttle movement on Takeoff

Post by Sudden81 »

Tim737800 wrote: 04 Nov 2021, 21:35 Hello Guys,
Im have a new Motorized throttle for a few days. It’s awesome to watch the levers move.
But I discovered, that the movement of the throttles after pressing TOGA on the Takeoff-run is way to slow.
I often reach 90-100 Knots before the engine takeoff power is set. In real life they take approx 1-2,5 sek to reach their power setting.

Would be awesome since taking off with high weight or on short runways is sometimes pretty close 😅



Thanks for the help

Cheers from rainy Germany
Tim
Do you have a video of that?

I think Ian D Williams sad it would take 4,5-5 seconds. But that is from idle to full. Maybe from 40%n1 to takoff thrust it will be 2,5 second if 80-85% n1 is commanded?

Very sad if it is 2,5 seconds from 0 to 100% n1. I have bin searching for the correct rpm motor for years.

One question that I wonder is. Does the handles move faster then the engines spool up? Is it the same in that case when the plane reduce speed in VNAV?

I can see one strange thing in this clip: https://youtu.be/JF4hMXI82-s

After TO/GA is pushed the TQ handels move quite fast to on posision then creaps the last cm is this done by the aircraft or by the pilots. If it was the plane that was doing that it is more logic that the handles would creaps the last millimeters?

Looking almost the same in this clip: https://youtu.be/eb36feRMTGI

In this clip it is eaven more clear, they klick TO/GA from idle.
https://youtu.be/5y0YnDLsyCI

It looks more like 4 second than 5.

Have never seen this before.

Best regards
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dvincent
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Re: Faster Throttle movement on Takeoff

Post by dvincent »

That is not a Prosim problem, it is an adjustment in the throttle.
Regards,
Dirk

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Sudden81
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Re: Faster Throttle movement on Takeoff

Post by Sudden81 »

dvincent wrote: 08 Nov 2021, 12:45 That is not a Prosim problem, it is an adjustment in the throttle.
dvincent what is not a ProSim problem?

The speed?

You are absolutely right IF ProSim's speed is correct. But you do not answer some of the questions that are asked.

Is ProSim's speed correct?

If the TQ handles move faster, the n1 has time to wind up. I guess so. I could also imagine that the Handles should not move faster than the motors have time to wind up? What's the point of that? But it is better for someone who has more knowledge to answer.

But the hardware you use naturally plays a role, if you use RC Servo and Pololu servo control cards, or Pololu JRK dc motor cards, or Phigets, it is clear that there will be a difference.

The hardware should follow what ProSim commands. Prosim should probably then command a certain speed? If the speed is then too low, then it is ProSim's fault. If the hardware is too slow, then it is obviously the hardware fault.

But there are a few mixed things in this matter.

As you can see in the last video clip, it takes about 4 seconds from idle to N1. If it takes the same time for ProSim to do this without hardware then you have just the right dvincent.

But maybe we should differentiate between n1 value and commanded handle position?

Are they really the same. We must get an answer to that, if we are to be able to answer anything.

If it is true that the speed quickly goes up to a value and then fine-tunes the last cm, then ProSim has not simulated this, and no one has noticed this.
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Sudden81
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Re: Faster Throttle movement on Takeoff

Post by Sudden81 »

I can see in my latest post I express myself very strangely. I can see that it is not easy to follow my reasoning.

Sorry for that.

I will see if I can get som help expressing what I mean.
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OE1CGA
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Re: Faster Throttle movement on Takeoff

Post by OE1CGA »

i my case (CFY v3) the T/O power is set and the A/C has not yet reached 30 kts on a rolling T/O.
Airport elev. 610ft.

So, this looks to be alright, maybe the throttle lever movement is just a little bit slow.
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Re: Faster Throttle movement on Takeoff

Post by willow »

Greetings

It seems we have two topics in his thread.

(1) The speed that the thrust handles move in relation to the speed that the handles move in the real aircraft (too slow); and,

(2) Whether ProSim calculates the correct %N1, and generates the correct speed when the autothrottle is controlled by ProSim (the position and speed of the thrust handles follow based on the hardware and software calibration).

The speed that the thrust handles move can be adjusted in the software, so that it matches the %N1 output that is being generated by ProSim (as @dvincent has correctly stated).

However, the speed that the thrust handles move can be very subjective - what is fast for one person may appear slow to another.

As @Tim737800 (original poster) stated that his thrust levers were moving more slowly than in a real aircraft, perhaps a video showing this can be posted along with a video from the real aircraft showing throttle movement. A 'rough' comparison in the speed at which the thrust handles move can then be done? Until this occurs, it's anyones guess..... :?:

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mickc
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Re: Faster Throttle movement on Takeoff

Post by mickc »

To settle the speed questions, the real throttles move like this:
In takeoff or go-around, the A/T moves the T/Ls at a rate of 13.5
deg/sec to a predicted position. For final adjustments, the A/T
moves the T/Ls at a maximum rate of 5 deg/sec. In modes other
than TO/GA, the A/T limits thrust lever rates to 3 deg/sec.

For descent retard from cruise flight, at FMC top of descent
(TOD) the A/T commands the T/Ls to reduce engine thrust to
idle. In descent RETARD, the thrust levers move to the aft stops
at 1 deg/sec.

The A/T goes into the flare retard mode during landing if on G/S
and in MCP SPD mode. The A/T commands the T/Ls to move to
the aft stops at 3 deg/sec. After landing, the T/Ls move to the
idle stop at 8 deg/sec. During the flare retard mode, the T/Ls get
to idle within 6 seconds.
Note that the full range of motion of the thrust levers is 84 degrees.

With a closed loop servo motor system such as a Pololu JRK (that has the PID settings properly tuned) Prosim replicates this extremely well.
Also, looking at the commanded N1 arrows on the engine display does not directly relate to the handle position.
On the real TQ, the movement is non-linear, so the lower range of motion adjusts the N1 quickly, but the upper range is more spaced out.
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Tim737800
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Re: Faster Throttle movement on Takeoff

Post by Tim737800 »

I will post a video of the levers… but. They correspond with the n1 indication. From IDLE to FULL POWER it takes about 8-10 seconds… way to much

But I will make a video
Building a Full size b737 Cockpit with galley and cabin inside of Ex Boeing 737-500 VQ-BAE
Converting OEM parts...
just ask if you are interested in measurements or anything else
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