Aviation Forums Forum Index Aviation Forums
Aviation discussions newsgroups
 
Archives   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

747 glide ratio

 
Post new topic   Reply to topic    Aviation Forums Forum Index -> Planes, gliders and flying in Australia
View previous topic :: View next topic  
Author Message
Mal
Guest





PostPosted: Tue Aug 10, 2004 10:30 am    Post subject: 747 glide ratio Reply with quote



Today at work we were discussing the 747 that went into the ash from the
volcano.

What is best glide ratio in a 747 with no power and at what speed in knots.

Thanks.

Mal




Back to top
John Ewing
Guest





PostPosted: Tue Aug 10, 2004 12:43 pm    Post subject: Re: 747 glide ratio Reply with quote




"Mal" <abuse (AT) bigpond (DOT) net.au> wrote

Quote:
Today at work we were discussing the 747 that went into the ash from the
volcano.

Here is one account - from Capt Eric Moody's website:
http://www.ericmoody.com

Quote:
What is best glide ratio in a 747 with no power and at what speed in
knots.

Thanks.

Mal

Cheers,
John



Back to top
JB
Guest





PostPosted: Wed Aug 11, 2004 9:51 am    Post subject: Re: 747 glide ratio Reply with quote

Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB


"John Ewing" <none@needed> wrote

Quote:

"Mal" <abuse (AT) bigpond (DOT) net.au> wrote in message
news:Dt1Sc.44053$K53.41744 (AT) news-server (DOT) bigpond.net.au...
Today at work we were discussing the 747 that went into the ash from the
volcano.

Here is one account - from Capt Eric Moody's website:
http://www.ericmoody.com

What is best glide ratio in a 747 with no power and at what speed in
knots.

Thanks.

Mal

Cheers,
John





Back to top
Mal
Guest





PostPosted: Wed Aug 11, 2004 11:19 am    Post subject: Re: 747 glide ratio Reply with quote

Aircraft (year) (L/D)max
Boeing B707-320 19.4
Douglas DC-8 17.9
Airbus A320 17.
Boeing 767-200 19.
Boeing 747-100 17.7
Douglas DC-10 17.7
Lockeed Tristar L1011 17.0
Douglas DC-9 (1966) 16.5
Boeing B727-200 16.4
Fokker 50 (1966) 16
Douglas DC-3 (1935) 14.7
Ford Trimotor (1927) 12.
Wright Flyer I (1903) 8.3


found it

I will stick with my 47

http://www.mals.net/camden/pages/DSC00666.htm


"JB" <jb0767 (AT) hotmail (DOT) com.au> wrote

Quote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB


"John Ewing" <none@needed> wrote in message
news:4118c2d0$0$19305$afc38c87 (AT) news (DOT) optusnet.com.au...

"Mal" <abuse (AT) bigpond (DOT) net.au> wrote in message
news:Dt1Sc.44053$K53.41744 (AT) news-server (DOT) bigpond.net.au...
Today at work we were discussing the 747 that went into the ash from
the
volcano.

Here is one account - from Capt Eric Moody's website:
http://www.ericmoody.com

What is best glide ratio in a 747 with no power and at what speed in
knots.

Thanks.

Mal

Cheers,
John







Back to top
BB
Guest





PostPosted: Wed Aug 11, 2004 1:30 pm    Post subject: Re: 747 glide ratio Reply with quote

JB wrote:
Quote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB



so (3*6076)/1000 or approx 18.2?


Regards,
BB.

Back to top
Martin Taylor
Guest





PostPosted: Fri Aug 13, 2004 2:24 am    Post subject: Re: 747 glide ratio Reply with quote

JB said....

Quote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

So you could kill the engines over my place and glide into Tulla.
Imagine the fuel savings!!!

What I reckon is ballsy is, aside from re-entry, is pointing the shuttle
at Edwards or the Cape for a unpowered landing. How they manage to get
it spot on every time (well, almost every time) is amazing.

Watched Discovery Channel and a show on the shuttle. They had a camera
on the flight deck. The woman in the right seat was reading off heaps of
numbers (probably speed, altitude and distance). Not a good time to ask
them "what time will we get home?" (as any parent with kids can
recognise...)



Back to top
BB
Guest





PostPosted: Fri Aug 13, 2004 6:04 am    Post subject: Re: 747 glide ratio Reply with quote


"JB" <jb0767 (AT) hotmail (DOT) com.au> wrote

Quote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB



Just curious..
Is that 240-250 knots well inside the windmill start envelope? (ie. Is there
a lot of room for error?)

Regards,
BB



Back to top
JB
Guest





PostPosted: Fri Aug 13, 2004 6:16 am    Post subject: Re: 747 glide ratio Reply with quote


"BB" <not (AT) all (DOT) com> wrote

Quote:

Just curious..
Is that 240-250 knots well inside the windmill start envelope? (ie. Is
there
a lot of room for error?)

Regards,
BB

It's right in the middle for the GE, but it's on the edge of the starter
assisted envelope on the RR. They need 280kias or so for a windmilling start
above about F200.

JB



Back to top
BB
Guest





PostPosted: Fri Aug 13, 2004 12:50 pm    Post subject: Re: 747 glide ratio Reply with quote

JB wrote:


Quote:


It's right in the middle for the GE, but it's on the edge of the starter
assisted envelope on the RR. They need 280kias or so for a windmilling start
above about F200.

JB



Thanks JB.. Kind of ties in with what we learnt regarding ground
starting of CF6 engines vs. RB211 engines (ie. the RR engines need more
air volume)...


Regards,
BB.

Back to top
JB
Guest





PostPosted: Fri Aug 13, 2004 9:08 pm    Post subject: Re: 747 glide ratio Reply with quote


"Martin Taylor" <mjpt57 (AT) yahoo (DOT) com.au> wrote

Quote:
JB said....

Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and
a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

So you could kill the engines over my place and glide into Tulla.
Imagine the fuel savings!!!

Which would be more than offset by the insurance costs......

Quote:

What I reckon is ballsy is, aside from re-entry, is pointing the shuttle
at Edwards or the Cape for a unpowered landing. How they manage to get
it spot on every time (well, almost every time) is amazing.

Watched Discovery Channel and a show on the shuttle. They had a camera
on the flight deck. The woman in the right seat was reading off heaps of
numbers (probably speed, altitude and distance). Not a good time to ask
them "what time will we get home?" (as any parent with kids can
recognise...)


On of the major problems with the design of the shuttle, is that the USAF
pushed for it to have a 1000 mile cross track capability. The USAF
eventually backed away from the shuttle, but, by then, their inputs had
dramatically affected the design. As a result, it is appreciably bigger
overall, and has a much bigger wing, than ever envisaged by NASA. The
problem with the bigger wing is that it keeps them in the area of max
heating for longer than would be the case with a smaller wing. We now know
what that does.....



Back to top
d&tm
Guest





PostPosted: Sat Aug 14, 2004 9:34 pm    Post subject: Re: 747 glide ratio Reply with quote


"BB" <not (AT) all (DOT) com> wrote

Quote:
JB wrote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and
a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB



so (3*6076)/1000 or approx 18.2?


wow, so a 747 has a better glide ratio than a Cessna , which I think is
around 9. I would never have thought that.

Terry



Back to top
matt weber
Guest





PostPosted: Sun Aug 15, 2004 1:20 am    Post subject: Re: 747 glide ratio Reply with quote

On Sun, 15 Aug 2004 07:34:30 +1000, "d&tm"
<tfmann (AT) iprimusREMOVEME (DOT) com.au> wrote:

Quote:

"BB" <not (AT) all (DOT) com> wrote in message
news:411a1f5e$0$18191$afc38c87 (AT) news (DOT) optusnet.com.au...
JB wrote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and
a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB



so (3*6076)/1000 or approx 18.2?


wow, so a 747 has a better glide ratio than a Cessna , which I think is
around 9. I would never have thought that.
Terry

Low speed wings generally obtain higher lift with higher drag. My POH

for a 182RG puts L/D at about 9. A late mode 210 is probably a little
better, but L/D at cruise for most big jets is in th 16-17 range. For
Concorde at Vr/Mgtow it was about 5 (which is why the loss of a single
engine is very unpleasant, the loss of 2 engines below about 275kt is
guaranteed to be fatal unless you have enough altitude to bring the
speed up to a place where L/ D is more favorable.

Back to top
Coop
Guest





PostPosted: Sun Aug 15, 2004 2:05 pm    Post subject: Re: 747 glide ratio Reply with quote

d&tm wrote:

Quote:
"BB" <not (AT) all (DOT) com> wrote in message
news:411a1f5e$0$18191$afc38c87 (AT) news (DOT) optusnet.com.au...
JB wrote:
Varies a lot with weight. Roughly 240-250 kias. It would go about 3 and
a
bit miles per thousand. Not that much different to a standard descent in
terms of distance, but about 40 knots slower.

JB



so (3*6076)/1000 or approx 18.2?


wow, so a 747 has a better glide ratio than a Cessna , which I think is
around 9. I would never have thought that.
Terry

Its all to do with aspect ratio and streamlining- the weight and size don't
play that big a part- except in setting the speed of the best glide ratio,
which is much higher on a heavier machine.
So a 747 can glide further for a given hieght than my Auster- but I know which
one I would rather be in if the power went off.

Coop


--
To reply, remove the nose wheel.....




Back to top
Gregory Bond
Guest





PostPosted: Tue Aug 17, 2004 5:53 am    Post subject: Re: 747 glide ratio Reply with quote

"d&tm" <tfmann (AT) iprimusREMOVEME (DOT) com.au> writes:

Quote:
wow, so a 747 has a better glide ratio than a Cessna , which I think is
around 9. I would never have thought that.

Glide ratio is pretty closely related to cruise fuel economy, so it's
really not that surprising after all!

Back to top
Display posts from previous:   
Post new topic   Reply to topic    Aviation Forums Forum Index -> Planes, gliders and flying in Australia All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB