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No. Of Jets & Slow Down Time  
User currently offlineJaemz From , joined Dec 1969, posts, RR:
Posted (16 years 4 months 4 weeks 20 hours ago) and read 1638 times:

my question is... can planes with more number of engines or more powerful ones stop more in time? perhaps an A340 or 747 can actually use a shorter runway to slow down than a 330 since their jets are more powerful to generate stronger reverse thrusts?

4 replies: All unread, jump to last
User currently offlineDas Flugzeug From United States of America, joined Nov 1999, 161 posts, RR: 1
Reply 1, posted (16 years 4 months 4 weeks 19 hours ago) and read 1591 times:

One cannot really compare the 747, as it is a much larger and heavier aircraft, and therefore has no twin engined counterpart.

As for the A340/330, no I do not believe the 340 is able to stop shorter. First, I believe it often comes in at a heavier landing weight = more momentum = more energy required to stop. Also, the 340 does not enjoy a thrust advantage, in fact, I believe it has less thrust. The 340's CFM 56 -5Cs each put out 34,000lbs as opposed to the 330's Trent 700 (example) which each put out 75,000 lbs. What it adds up to is a lighter plane (330) coming in with more thrust to reverse.

Also, I believe thrust reversal only accounts for about 15% of braking force, but I could be wrong about that.

Rock on,


User currently offlineJaemz From , joined Dec 1969, posts, RR:
Reply 2, posted (16 years 4 months 4 weeks 16 hours ago) and read 1585 times:

Howabout we compare the 747-400 to the 747-300?
the 400s have more powerful engines, they carry about the same capacity as the 300s, are they able to stop shorter? i know maybe all the avionics add to the weight of the 400, but i assume they are not too significant compared to the boost in their engines over the 300s

User currently offlineBuff From Australia, joined Mar 2007, 0 posts, RR: 1
Reply 3, posted (16 years 4 months 4 weeks 15 hours ago) and read 1581 times:

I can't give you a specific answer to your specific question, but to assess the effectiveness of reverse thrust, you must compare the thrust to aircraft weight ratio, plus a whole lot of other things. And as Das Flugzeug offered, wheel braking is much more effective at stopping the airplane. Reverse thrust reduces in effect significantly as the aircraft decelerates below 100 knots.

So there is really no answer to your question other than to compare performance charts for each type.

Best Regards,


User currently offlineJaemz From , joined Dec 1969, posts, RR:
Reply 4, posted (16 years 4 months 4 weeks 11 hours ago) and read 1577 times:

Ok thanks, well, i was actually wondering if the A340 can stop more quickly than the A330 since it has got an extra pair of muscles to boost the reverse process. thanks again anyhow...

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