Spooling up delay driving me mad!

[David Rogers]

Hi all,

Can anyone advise me how to reduce the delay that occurs in the engines spooling up, when I advance my throttles, when using PM ?

I wholly appreciate there is a spooling delay on a jet engine but on my set-up, when I advance throttles nothnig happens for 3-4 seconds before the engines start to spool, which is unrealistic.

Also, I believe this issue is causing some problems I have with speed control using the MCP, (where speeds are shooting through because of slow spooling).

I checked the 737700 file in the CDU for this but couldn't find anything that obviously relates to this spooling speed parameter.

Any pointers ?

Thanks,

[Ray Proudfoot]

David,

If you hit F4 (max thrust) do you still get the problem? If you don't then try calibrating your throttle. If the problem is still there with F4 then sorry, don't know the answer.

[Bob Reed]

I have watched many videos on 737 takeoffs.. There is a substantial delay in spool up when you advance the throttles. You are supposed to do it in at least 2 stages... 40 to 60% "depending on who you talk to" and then advance to take off thrust.. Watch the videos there is a delay..

[Tomlin]

Slightly off topic, but not really...

I have noticed lately that when starting the engines on the Learjet PMRJ, that sometimes the first stage (N1) is not showing hardly any movment at all until after getting a lightoff at 21% N2. Then, sometimes I do get normal slow movment on N1. It's like a software lag or something. Also, my Copilot PMRJ screens have been in weird places lately when starting that client, it's moving after starting it's PC.

[Michael Carter]

I used to fly a diffrerent 727 before the DF came along, and it too had engines that took forever to spool. JT-8D's don't take THAT long to come up from ground idle.

The parameters to change are in the .air file and I was able to get a more realistic spool-up time by adjusting a few parameters.

I don't know where it is in PM, but I think that has more to do with the flight model than the PM program.

[sas550]

Check if flaps, spoiler and trim seem to respond slow aswell. If so it's most probably network lag. I suffered from it at before I tweaked my lan and everything that was supposed to show on that pc runnin the GC software (upper eicas) lagged behind with 5/10 seconds.

[David Rogers]

Cheers guys, I'll check these things out. As I said, I know there is a spool up delay for real, but this case is excessive. I suspect Anders is correct and it's a network delay that I'll need to tweak out.

[Bob Reed]

Are the engines actually taking that long to spool, or is it just the PM display taking that long to catch up...?

[rob747]

Interesting reading this. I've noticed a considerable slow down of spool up to Take Off Thrust when useing the TOGA on my 747. This was fine up until the latest version. Example: Arm VNAV and Autothrottle's (GC Displays Blank TOGA TOGA, VNAV Armed). Spool up to 40%, Engine's stable so then hit THR (TOGA) and then it's real slow getting to take-off power..... like I said - only started to happen in this latest GC version.

[sas550]

Interesting reading this. I've noticed a considerable slow down of spool up to Take Off Thrust when useing the TOGA on my 747. This was fine up until the latest version. Example: Arm VNAV and Autothrottle's (GC Displays Blank TOGA TOGA, VNAV Armed). Spool up to 40%, Engine's stable so then hit THR (TOGA) and then it's real slow getting to take-off power..... like I said - only started to happen in this latest GC version.

Hi Rob! This is a known prob with the latest MCP build. Enrico is working on it. (Hmm something familiar with this last sentence) :)

Revert to an earlier mcp build or spool them up manually until you're almost there before hit toga.

[rob747]

Glad to hear it!! Well - at least I know it's not my set up now!!! :)

Interesting to see when the next update will be.....

[David Rogers]

Are the engines actually taking that long to spool, or is it just the PM display taking that long to catch up...?

Hi Bob,

A bit of both I think but probably more along the lines of the actual spool (and thus aircraft performance being affected, not just instrument readings).