Rate of Climb for Commercial Airliners?

[BoDEAN]

I hear the U2 Spyplane climbs at 18,500 FPM.

Shesh!

 

[atldc9]

My B717-200 weighs 120,000 lbs, and has 37,000 lbs of thrust, so about a 3.2 to 1 power to weight ratio. At max gross, 1000' pressure altitude (ATL), and normal temps, ie 70-85 F, it will climb out at better than 2000 fpm all the way to 310.

Lighten it up and cool it down, ie TO weights around 100 k and temps in the 40- 60 f range., and you have 3000 plus to 350.

That is with climb speeds of 300 KIAS until crossing over to M 0.77, which is usually long range cruise for us. We fly a fuel efficent profile, not for speed. Mmo is 0.82, and it will do every bit of it, it just gets better mileage around M 0.77.

I flew one empty with not much fuel once, TO weight about 84,000 lbs. Now that was a rocket ship. 6000 fpm plus all the way to 370.

Typical times to clime are about 18-21 minutes to the 350-370 range.

 

[banned username 2]

I flew one empty with not much fuel once, TO weight about 84,000 lbs. Now that was a rocket ship. 6000 fpm plus all the way to 370.

Thats amazing because I did a maintenance flight in our 900EX and I was at 33,000 lbs. T/O weight with 15,000 lbs of thrust (2.2:1 ratio slight better than your 84,000 lb 717 was that day)

And we definately did better than 6000 FPM down low (below 20,000) but by the time we got into the 30's it was down to around 3,500 FPM and passing through 37,000 it was probably 2,400 FPM and passing throught 43,000 it was down to around 1,200 FPM....

Let remember folks, jet engines are NORMALLY aspirated engines... they lose thrust as you climb...a 5,000 lbs thrust engine puts out about 1,120 lbs of thrust at 40,000 ft at M0.80

So to be doing 6,000 FPM (steady state) up at FL370 you would have to be doing better than 15,000 FPM (steady state) down low... With a 2.2:1 thrust ratio I just don't see that happening (steady state) I flew a Lear and had taken off with a 2.0:1 ratio and only saw 10,000 FPM down low (steady state)

 

[atldc9]

Sorry Falcon Driver- You are right, I went back and edited the post to add the climb altitudes, and didn't see where I put that one.

On that ferrry flight, it was an INITIAL climb greater than 6000 fpm, and by the time we leveled off at 370, it was down to about 2500-3000.

Sorry for the mistake.

 

[banned username 2]

Sorry Falcon Driver- You are right, I went back and edited the post to add the climb altitudes, and didn't see where I put that one.

On that ferrry flight, it was an INITIAL climb greater than 6000 fpm, and by the time we leveled off at 370, it was down to about 2500-3000.

Sorry for the mistake.

No problem, just want to make sure the "fish" isn't getting TOO big in these stories!

Can you believe people accuse me of being anal retentive? Such Nerve!

Sorry, I am a stickler for accuracy....

Fly Safe!

 

[atldc9]

No worries, and I keep my fishing stories at http://www.cafelocale.com/cgi-bin/show.cgi?13/13.html

But anyway, back to engines and climb performance. The reason the 717 climbs so well normally is that it uses the br-715 engine. That engine is thermodynamically rated at 24,500 plus pounds of thrust. It was certified on the 717 at 21,500, flat rated to some ridiculously high temp. AirTran only bought 18,500 pounds of thrust from each engine, which is still plenty. So you see, the 18,500 we pay for, is from an engine thermodynamically rated at 24,500 + lbs of thrust. That is a lot of flat rating, and hence maintains the climb rate to a higher, or hotter temp.

And the tuna were that big this season.

 

[banned username 2]

Yeah, understand the flat rating... our engines are flat rated to ISA+17°C (90°F @ SL)... Makes a big difference!

Fly Safe!