[Question to RL CRJ pilots] Thrust management, how to? (no bug in here!)

[charly]

Hi folks!

Question to RL pilots.

My previous love, the Piaggio Avanti Alterna, had quite simple thrust rules: Full Power from TO to cruise. A Fadec would do the job to limit torque up to a certain level, where it would reach and keep 100% N1. In cruise, full power would not exceed VMO.

With CRJ, things do not seem that easy. Let's take it step by step.

1: TO

From FMC, we're given a TO thrust setting, depending on (from what I've read here) runway elevation and OAT. This does quite good job on long runways, but I've already scratched the ILS aerial with the gear on LFLB with that setting...

So question: shouldn't the TO thrust setting also depend on weight and RWY length? Are there any RL charts for that? (I guess also V1 should depend on these parameters, so if anybody has got these charts...)

2: Climb

I understand thrust has to be increased when air gets thinner, to keep some adequate climb rate. From Maksim (aviatop) post here, I can see that effectively thrust goes up with FL. Again, how to decide N1? Is there any ITT limit, or climb rate @ given mach to hold, or N2 limit, or any other RL rule?

3: Cruise

No doubt here, I actually set N1 to keep Mach.75. But is this actual RL speed used for cruise on the CRJ?

Just to get it "as real as it gets"....

Thks!

Charly

Edited February 4, 2012 by charly

[aviatop]

Hi Charly!

Will try to answer on your questions.

1. TO thrust setting depends on a big number of properties, and runway length and slope, too. The proper setting real pilots can find in Runway Analisys Table, which is produced on a special software by a qualified engineer. This table is made for a company routes of air carrier, if you would like to see an example of it, I can upload.

2. Yes, you right. Pilots increaseng N1 with altitude. You can find a scan of example of flight EDDV - UMMS. What about limits of N1, I dont know, but on practise I can say than I didnot see N1 more than 96%. Just remember if your V/S decreases less than 300ft/min inclusive during climb - you need to stop it.

3. CRZ speed depends on situation. Somebody likes faster, somebody - slower. On practise we flying from 0.68 to 0.8, depending on captain, aircraft condition, payload, weather, route length, etc..

If any questions - you are welcome.

Maksim.

[charly]

Thks Maksim!

This table is made for a company routes of air carrier, if you would like to see an example of it, I can upload.

I'd love to!

2. Yes, you right. Pilots increaseng N1 with altitude. You can find a scan of example of flight EDDV - UMMS.

I've checked the scan quite a lot of times, and it looked to me that it must have been an ATHR-equiped CRJ. Indeed, the increase is sooooo smooth, I can't beleive it was hand-made! I'll apply as personnal rule to keep 1500ft/min @.7M, stopping @96% N1. If ever you find a RL rule for N1 setting, I'd love to know.

Thks again! keep on posting new info here.

Charly