fuel flow of erj135?

It varies widely but I say average is 2500 PPH total in cruise pulled back a little bit. I've seen lower and much higher if we are going home. :)
 
Too much!

An approximate numeral answer would be 1200PPH per side at around the normal cruise speed.
 
Actually, at FL300 the fuel flow would be more like 1550 pph per engine. At FL350 the fuel flow would be about 1230 pph per engine.
 
FlyChicaga said:
Actually, at FL300 the fuel flow would be more like 1550 pph per engine. At FL350 the fuel flow would be about 1230 pph per engine.
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Maybe in the detent but I remember seeing it lower. Between 1200 and 1300 a side at like .70 or so. I will keep an eye on it when I go back in a couple days.
 
You guys fly at .70M? The only time I'll fly that slow is in turbulent conditions or if we are well ahead of schedule. Normally flying that slow only helps save fuel when we have a large tailwind, whereas flying at .76-.78M gives us our best fuel efficiency.
 
Speaking of cruise speeds, there was another Southernjets flight crossing thru "London Control". "London Control" asks, "Delta XX, say mach number"

"Ahhh, we're ahhhh seven six eight"

That last digit scrolls around like a freaking slot machine!
 
Doug Taylor said:
Speaking of cruise speeds, there was another Southernjets flight crossing thru "London Control". "London Control" asks, "Delta XX, say mach number"

"Ahhh, we're ahhhh seven six eight"

That last digit scrolls around like a freaking slot machine!
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:D:D:D:D
 
Perhaps, I haven't really looked into it. I think it has more to do with not wanting to be 30 minutes early on every flight because for some reason we are always horribly over blocked. On our longer legs or going home of course we will get it up close to the red line but for the most part we will pull it back to around .70-.72. Our flights in the 135 are usually under an hour with the exception of a couple.

How did you figure that it is most efficient at .76? I can see it on longer flights but if a flight is an hour and you are burning 500 more pounds of fuel and only getting there a few minutes earlier it doesn't make sense to me.

But I dunno, we fly slow, we get paid by the minute... :)
 
For what it's worth Mach .1 ~ 60 kts. .01~6 knots .001 ~ 0.6 knots.

ROOOOOOUGHLY. But perhaps Tgrayson could elaborate.
 
SoCalAprch said:
How did you figure that it is most efficient at .76? I can see it on longer flights but if a flight is an hour and you are burning 500 more pounds of fuel and only getting there a few minutes earlier it doesn't make sense to me.
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Basically, by flying slow into a headwind you are staying aloft longer than you would by flying faster. You may have a fuel flow of 2400 pph compared to 3000 pph, but if you add 30 minutes to the flight, have you gained anything? All you've done is stay airborne for an extra 30 minutes and broke even on fuel burn.

Surprisingly, I climbed one evening at 310 knots and transitioned to .72M up to FL370, accelerated to .78M, then did a 4.0 degree descent to our destination. We shaved off over 20 minutes of scheduled flying time from our paperwork, and saved over 1000 lbs of fuel. It was the complete opposite of what you would expect from that profile.
 
FlyChicaga said:
Basically, by flying slow into a headwind you are staying aloft longer than you would by flying faster. You may have a fuel flow of 2400 pph compared to 3000 pph, but if you add 30 minutes to the flight, have you gained anything? All you've done is stay airborne for an extra 30 minutes and broke even on fuel burn.

Surprisingly, I climbed one evening at 310 knots and transitioned to .72M up to FL370, accelerated to .78M, then did a 4.0 degree descent to our destination. We shaved off over 20 minutes of scheduled flying time from our paperwork, and saved over 1000 lbs of fuel. It was the complete opposite of what you would expect from that profile.
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I agree with you, however what I am saying is that I don't think you are gonna shave 20 min off of a 45 minute flight and I don't think flying at .78 going from CVG - IND is saving you enough time to save you fuel. Now if you are doing 1.5 hour flights or longer then yes by all means you are 100% correct. If we go by Doug's simple math you are only going 36 knots faster, on an hour flight you will only make it there a couple minutes before yet you will need to make up at least 15 minutes to save the fuel. And this will all have to be made up in Cruise considering that we are climbing and descending at the same FF rates.
 
I checked my answer when I posted it against a large size high resolution picture I took a few weeks ago; in the climb passing FL310 it was 1550PPH if you are curious taseal. Now that I think of it, that probably is close to that altitude and the 1200 figure probably is more geared towards 350 and up. On the day I took that picture though, it couldn't have been more than about 1400PPH at FL310 once CRZ would be set and the power back a smidge. Variance with conditions.
 
While a rule of thumb is up here being read, I'll add one that I think is useful -

.6 mach = about 6 miles per minute
.7 mach = about 7 miles per minute
.8 mach = 8 miles a minute
Right on up to NJA_capt velocity
 
Nerded out and looked at a big picture I just took as well and at 340 at .76 we had 1200 per side. So I figure .72 at 300 will be around 1300 per side.
 
A good rule of thumb in the EMB-145 is that your total fuel burn will be your indicated airspeed x 10. This seems to hold true at any altitude, and is very handy to know. No need to fish around for power settings, simply set the fuel flow at 1250/side, and voila 250 knots at any altitude (okay, in reality it gives you more like 240 (who wants master warnigs going off anyway) and will vary slightly depending on weight, but close enough assuming you're clean).

At FL 300 and M.76, you're indicating about 280 knots I'd guess, so that'd be 2800 lbs/hr. You should probably subtract about 5% for the EMB-135 due to the lower weight, so about 2700 lbs/hr at FL300 and .76 in the EMB-135.

Typically we cruise at FL350-370 for flights longer than 300 NM or so....you'll see about 2400-2600 lbs/hr at those altitudes if you wish to cruise at M.76-.80.

I believe the controllers in Houston stated they observed higher angles of climb by jets when there was no 250 knot speed limit below 10,000 feet.

Pilots that think they're saving tons of fuel by climbing slow in a jet are funny. Pay attention to your vertical speed next time you get restricted to 250 in the climb. It's probably not that much higher than what you'd be doing at 290-300+, not to mention you're covering ground about 100 knots more slowly. I would not try and outsmart the people that wrote your manuals, odds are there were people smarter than you writing than those things, with more data to back up their knowledge. But hey, I could be wrong, I'm just a pilot.
 
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