flying-b773
Posts: 378
Joined: Sat Apr 28, 2001 11:24 pm

Size To Speed... Concorde Excluded!

Thu Jul 25, 2002 4:10 am


no concorde here....

the speed of the planes are kinda acording to size.

though the biggest, the 747 and 777 flies the faster..... followed by the A330/340 , the A310/300 and the B757/767 almost the same, than by the smaller A320/B737. as the size gets smaller, the speed decreases as well.

a flight from akl to sin may jolly well create a difference of more than 30 minutes if it were to be flown by the 747 and the 767/340.

pardon my poor knowledge here, but why is it so?
 
Arsenal@LHR
Posts: 7510
Joined: Tue Mar 20, 2001 2:55 am

RE: Size To Speed... Concorde Excluded!

Thu Jul 25, 2002 5:10 am

The 744 is the fastest subsonic jet, it has a higher cruise speed than all other aircraft, the 777 comes second, therefore the flying time is slightly decreased. Maybe someone can elaborate a bit more?
In Arsene we trust!!
 
strickerje
Posts: 706
Joined: Tue Feb 20, 2001 1:35 pm

RE: Size To Speed... Concorde Excluded!

Thu Jul 25, 2002 6:08 am

I'm no expert, but I'll give it a shot -

You've said that the fastest aircraft are the 777 and 747, followed by the A330/A340. You might also notice that these are also the longest range. For a regional jet, MD-80, or 737 flying 1000 miles or less, speed is not imperative because most of the scheduled time is cusioning for traffic and delays. On intercontinental flights, the relatively small difference does make a difference.

Eg: 565 miles per hour is the published cruise speed of the 747-400, and I'll estimate 500 miles per hour for a smaller regional aircraft.
* ATL-GPT (351 miles) - @500mph = 0:37, @565mph = 0:42
Once you add the time to takeoff and climb and waiting in traffic, that's almost no difference.
* ORD-HKG (7793 miles) - @500mph = 15:35, @565mph = 13:48
Time to takeoff and climb and waiting in traffic is roughly the same whether you're going 500 miles or 5000, so here the near 2 hour difference makes a big difference. So you can see why, for the larger and longer range aircraft, it is worthwhile to put forth the extra research and development time and money in squeezing out the highest cruise speed possible without harming the fuel economy.

-Jeffrey
 
strickerje
Posts: 706
Joined: Tue Feb 20, 2001 1:35 pm

RE: Size To Speed... Concorde Excluded!

Thu Jul 25, 2002 6:15 am

After all that editing and proofreading, seems I can't make one post without screwing something up...

ATL-GPT (351 miles) - @500mph = 0:37, @565mph = 0:42

Those times should have been reversed.

Higher speed = shorter time. Embarrassment
 
slawko
Posts: 3742
Joined: Tue May 25, 1999 7:40 am

RE: Size To Speed... Concorde Excluded!

Thu Jul 25, 2002 7:19 am

I think strickerje got it right, the smaller aircraft can fly slower because the flights that they are used for are relatively short. If you look back in time speed was a much more important factor to companies, the 727 for example is very very fast as compared to current aircraft that serve the same role, same goes for the 707, DC8, TU-154, IL62. Back then fuel was cheap and speed was more important, today airlines have higher fuel costs, and so going M.80 instead of M.84 on a short flight will save millions of dollars each year in fuel costs, while only costing the airline 3 or 4 mins per flight on the schedule.
"Clive Beddoe says he favours competition, but his actions do not support that idea." Robert Milton - CEO Air Canada
 
high_flyr69
Posts: 497
Joined: Mon Apr 30, 2001 6:19 am

RE: Size To Speed... Concorde Excluded!

Thu Jul 25, 2002 4:06 pm

The 727-200 advanced was also a very fast jet. From a book i read i found out it could cruise at 950kph...quite a performance for a small airliner
Diplomacy is the art of saying 'Nice Doggy' until you find the shot gun