My JS41 performance during the cooler spring season was great; would get decent climb rates without AOA icing and EGT to the max line.

 

This summer, I'm struggling to get above 11,000 ft.

My TAT at 11,000 ft is 12* C and the SAT is 6* C as I'm flying right now.

 

Is the air just too warm for me to get more power out of the engines?

Are you running 100% rpm?

How heavy are you?

 

Glenn Davy

Torque is 100%, fuel loaded was 35% of max, with a PAX & cargo of 4994.

I wasn't heavy at all.

Well, I know I had a heck of a time getting a J31 at about 95% of MTOW to climb with 500fpm+ past FL100 last week with about the same ambient temperature. But the J41 has about 500+ SHP more per engine and if it's not heavy it should be able to climb without much of a problem past FL110 as far as I know. If it was the temperature, I think you would have been EGT limited and not able to run 100% torque.

 

I think I've read about a bug with air temperatures and performance before, but I can't remember if it was with the J41 or another aircraft. I guess that's not much of a help, but you might want to try and setup the same situation a couple of times. See if it happens every single time or if it's a bug that happens once every X times.

I flew the same route twice in a 24 hour period. I had performance loss on the engines during both flights. If it's a bug it's only appearing when FSX is set to warmer weather, because I sure wasn't seeing this happen during winter/spring.

That's interesting. Not sure what to say. I went out today from Dulles back to Westchester using real weather (and it was HOT), and loaded to about 21,500 lbs at takeoff. I didn't have any problems getting to 17,000 (still climbing about 800 to 900 fpm at that point. I did have to watch my EGT's on the way up, that's for sure. On takeoff I was temping out before I got to 100% TRQ, so it was a pretty warm day. One would think I'd see the same thing as you. That's odd. I don't know what to say on that. Sorry.

 

Glenn Davy

What do you mean by struggling?

What was your weight?

You had 100% TQ, but what was your RPM setting?

What IAS are you using?

What do you mean by struggling?

What was your weight?

You had 100% TQ, but what was your RPM setting?

What IAS are you using?

 

I mean the plane struggles to climb, doing only about 300-400 fpm with an IAS of 170.

My weight isn't the problem.

My payload is 4994 lbs with 2000 lbs of fuel, plus the empty operating weight of the aircraft, 14647 lbs.

Altogether about 21641 lbs.

 

I don't recall the RPM numbers, but I had the EGT to the max line.

Sounds dumb, but try another flight under the same conditions. If you find you are climbing ok, drop your gear and see what happens. I know, I know, but just try it. It wouldn't be the first time someone (not me, of course (err, ahem ) :P ) forgot to raise the gear, or accidentally dropped it. Flaps would be another thing to check.

 

Glenn Davy

Yeah I triple checked the gear and flap handles on both flights.

The aircraft was clean. I just don't get it.

By the way, is this when using a weather engine like REX (Essential or other) or AS2012 (or earlier version)? Or with just the FSX default weather engine? Addon weather engines sometimes create weird problems like this, even when they are coded exactly "by the book" so to say.

 

Otherwise, if the problem persists there are a couple of options:

 

- Set up a scenario in which the problem occurs for you. Describe how to set it up, and we can then double check it on our J41's.

- Reinstall the Jetstream 41 and see if the problem persists

- Raise a support ticket with PMDG if all else fails?

 

I hope we'll get it fixed somehow for you :P.

Here's a couple more things to try as experiments:

 

1. When it happens, try leveling off and doing a slow descent a thousand feet and then restart your climb and see if it's better. (It worked for me once and I want to see if it works for you.)

 

2. Try flying 'spring' again and seeing how it does.

 

Also, make sure your RPM is 98% as close as you can get it. I'm also assuming your engine anti-ice is off.

 

Also, I wonder what would happen if you climbed at a higher speed up there...say, 190. The added airflow might actually increase your available power because of lower EGT?

Going to try another flight this week, I'll report back.

Thanks for the responses thusfar.

If you fly online, make sure you're not using FSINN weather. It has a bug that makes the temp warmer as you increase altitude.