Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Does Not Look Like 190 Mph To Me  
User currently offlineWardialer From United States of America, joined Sep 2001, 1183 posts, RR: 0
Posted (11 years 6 months 1 week 1 day 20 hours ago) and read 9795 times:

Whenever I see like a B737 or B747 on a take-off roll, it does not seem like its going 150 to 190 mph.

And BTW, I do not believe at all that there going that fast at all, its more like 110 mph.

Please dont tell me that on a 6700-foot runway a B737 can acheive a 155 mph ground speed. Thats hard to believe!!!!!!

Seriously speaking of my own opinion, these take-off rolls have to be in the range of 80 to 110 mph the maximum. And same goes for a B747.

One proof might say it all, but until then I just dont believe it.

72 replies: All unread, showing first 25:
 
User currently offlineDoug_Or From United States of America, joined Mar 2000, 3443 posts, RR: 3
Reply 1, posted (11 years 6 months 1 week 1 day 20 hours ago) and read 9737 times:

welll the large size of the aircraft may make their actaul speed harder to identify to the untrained eye. I can assure you that most large transport aircraft will usauly have a rotate speed at least in the 115-145 knot range (about 140-180 mph). weather or not you choose to believe this is of course up to you.


Please dont tell me that on a 6700-foot runway a B737 can acheive a 155 mph ground speed. Thats hard to believe!!!!!!


welllllll do the math. or the physics. whatever. MGTOWs and engine thrust ratings are widely availble. pick a plane and go at it!



When in doubt, one B pump off
User currently offlineAaron atp From United States of America, joined Mar 2000, 533 posts, RR: 2
Reply 2, posted (11 years 6 months 1 week 1 day 20 hours ago) and read 9732 times:

it's an optical illusion my friend...

it has to do with how you brain processes information sent by your eyes.


It's getting late, I'm sure someone can fill in the details of monocular vision cues...

If not, I'll give it some thought and post a followup tomorrow


User currently offlineDoug_Or From United States of America, joined Mar 2000, 3443 posts, RR: 3
Reply 3, posted (11 years 6 months 1 week 1 day 20 hours ago) and read 9729 times:

Please dont tell me that on a 6700-foot runway a B737 can acheive a 155 mph ground speed. Thats hard to believe!!!!!!



also, they must be able to do this in much less runway- an a/c must be able to accelerate and then stop in an emergency to be allowed to take off fro ma runway- for instance on that 6700' runway the a/c may rotate at 3000'



When in doubt, one B pump off
User currently offlineMjzair From United States of America, joined Nov 1999, 401 posts, RR: 0
Reply 4, posted (11 years 6 months 1 week 1 day 20 hours ago) and read 9723 times:

You judge speed based on the amount of time an object takes to travel a distance equal to its length.
For example a baseball will always look like it is going faster than a 747 if both are travellin at 100 MPH because a baseball travels the distance equal to its size (i.e. 2 inches) a lot quicker than it would take for the 747 to cover a distance equal to its own.
While watching planes land, look at an RJ. I would guess that a typical approach speed is 130-140, not too much different than a 747. But, you will think that the RJ is travelling faster because it is so much smaller.


User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 5, posted (11 years 6 months 1 week 1 day 19 hours ago) and read 9697 times:

There is 2 different side to this. If you watch a jet taking off from an observation area- i.e a 737 or a 747 then i agree it doesn't look as if the jet is going very fast at all. As someone mentioned above this is due to the large size of the aircraft. If you look from a pax point of view during the takeoff roll, it will appear that you are going very fast indeed. Just look at the runway go by below you as the plane rolls down the runway. It's all an illusion.

User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 6, posted (11 years 6 months 1 week 1 day 17 hours ago) and read 9640 times:

As an addition to what i said above look at the difference between an F16 taking off and a 737 taking off. They both rotate at approximately the same speed, only the F16 looks like it's going a lot faster at that point because it is so much smaller. I noticed this at an airshow i was at recently. This 727 did a 100 ft runway fly-by at around 250 kts and it really didn't look like it was going that quick. Then when the F16 did the flyby at similar velocity it looked much quicker!

User currently offlineDragogoalie From Australia, joined Oct 2001, 1220 posts, RR: 6
Reply 7, posted (11 years 6 months 1 week 23 hours ago) and read 9440 times:

Yeap, Its a conspiracy, they're all really going 30 knots, you're right, everyone else is wrong :-p


Formerly known as Jap. Srsly. AUSTRALIA: 2 days!
User currently offlineSccutler From United States of America, joined Jan 2000, 5618 posts, RR: 28
Reply 8, posted (11 years 6 months 1 week 22 hours ago) and read 9420 times:

...of course, in an A-340, there is this concern.

(ducks for cover)



...three miles from BRONS, clear for the ILS one five approach...
User currently offlineAA61hvy From United States of America, joined Nov 1999, 13977 posts, RR: 56
Reply 9, posted (11 years 6 months 1 week 22 hours ago) and read 9404 times:

Once again, damn physics!
--
Yeah the A340 usually takes off going 50mph, climbing at a rate of 100 feet per minute  Wink/being sarcastic. I actually love the A340!



Go big or go home
User currently offlineFSPilot747 From United States of America, joined Oct 1999, 3599 posts, RR: 12
Reply 10, posted (11 years 6 months 1 week 21 hours ago) and read 9396 times:

"Please dont tell me that on a 6700-foot runway a B737 can acheive a 155 mph ground speed. Thats hard to believe!!!!!!"

Well allegedly this DOES happen so you might just have to accept it. It's harder to believe that you don't believe it. But, I like the way Drago put it. Just keep believing that..

FSP



User currently offlineWardialer From United States of America, joined Sep 2001, 1183 posts, RR: 0
Reply 11, posted (11 years 6 months 1 week 21 hours ago) and read 9393 times:

So there actually taking off from the ground at a speed of MORE than 80 mph right?????



User currently offlineTimz From United States of America, joined Sep 1999, 6903 posts, RR: 7
Reply 12, posted (11 years 6 months 1 week 20 hours ago) and read 9386 times:

Okay, let's take a well-loaded 747-400, taking off at 400 tonnes. At zero mph the four engines produce something like a thousand kilonewtons; at takeoff speed it's a lot less, but dunno how much less. What if the average force during the takeoff is, say, 600 kN? That makes the average acceleration 1.5 meters per second per second, so in 50 seconds they're up to 75 m/sec equals 145.8 knots, having covered 1875 meters equals 6152 feet.

So what's hard to believe? Or are you just pulling our legs?

[Edited 2003-06-26 04:24:24]

User currently offlineContinental From United States of America, joined Jun 2000, 5522 posts, RR: 17
Reply 13, posted (11 years 6 months 1 week 20 hours ago) and read 9392 times:

737 V1 is about 145 knots. That's about 167 mph at the moment of rotation. When I fly Continental from MSP, we're always in a 737. The 737 rotates full about when the runway is halfway done, that's about 5,000-6,000 feet, I'd imagine if you used the rest of the runway, you can get near 240+MPH, so it is indeed an illusion. When I see an airplane takeoff, it may seem slow, it's just the distance that's screwin' with ya.

co


User currently offlineLstc From Canada, joined Jun 2003, 320 posts, RR: 0
Reply 14, posted (11 years 6 months 1 week 20 hours ago) and read 9370 times:

Well...ground speed at takeoff can be 80 mph....if the wind is right down the center of the runway at 60 mph!

 Smile


User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 15, posted (11 years 6 months 1 week 18 hours ago) and read 9342 times:

It's the magic elves that use Santa's magic to get the 747 into the air at such a rediculously slow speed. If you listen really closely, you can hear them jingling and whistling as they work!  Big grin


Chicks dig winglets.
User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 16, posted (11 years 6 months 1 week 17 hours ago) and read 9323 times:

The brain can play some funny tricks on you. Have you heard of the visual illusion where the moon appears MUCH larger when it's near the horizon as compared to when it's directly overhead. The moon never actually changes size throughout it's movement across the sky, but you'd swear it's 2-3 times larger when it's near the horizon.

User currently offlineHa763 From United States of America, joined Jan 2003, 3673 posts, RR: 5
Reply 17, posted (11 years 6 months 1 week 14 hours ago) and read 9310 times:
Support Airliners.net - become a First Class Member!

It looks slow because of the distance between you and the moving object. You would tend to judge speed by its size and how fast it moves through your field of vision. The farther away the moving object is, the larger your field of vision is. Ever notice how slow and long it takes an airplane to pass over when you spot one way up in the sky? It still is going 400+ kts but looks like it is going much slower because you are watching it move through a bigger space.

User currently offlineRick767 From United Kingdom, joined Jan 2000, 2662 posts, RR: 51
Reply 18, posted (11 years 6 months 1 week 13 hours ago) and read 9292 times:

On a similar vein to Ha763s comment, when we had visitors to the flightdeck in the past a very common question (or comment) would be "It doesn't seem like we're moving very fast".

That is simply because at 37,000ft there is nothing close to the aircraft against which to relate it's speed.

Travelling at 550mph across the ground or sometimes even faster simply cannot be judged from that height. Opposite direction traffic on the same airway 1,000ft below or above also travelling at 550mph is an incredible sight though, that really makes you realise how fast you're going!

Anyway to put some figures on the original question for the 757 we will generally rotate at about 135-145 knots (155 - 167 mph) depending on weight and flap setting. On the 767-300 for a longhaul trip at 180 tonnes we're looking at 164 knots rotate speed with a Flap 5 take-off (189 mph).

So yes, we are going that fast. Honest  Big grin



I used to love the smell of Jet-A in the morning...
User currently offlineManzoori From UK - England, joined Sep 2002, 1516 posts, RR: 33
Reply 19, posted (11 years 6 months 1 week 7 hours ago) and read 9244 times:

It's the magic elves that use Santa's magic to get the 747 into the air at such a rediculously slow speed. If you listen really closely, you can hear them jingling and whistling as they work!


Don't be ridiculous! Everyone knows it's the collective willpower of the 400 or so people on board that's keeping that 747 aloft. It's amazing what willpower can do for you... just ask Yoda!

 Wink/being sarcastic

Rez



Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 20, posted (11 years 6 months 6 days 17 hours ago) and read 9155 times:

Will power? Oh, come on! That theory was discarded 30 years ago! It is all PFIL, Passenger Fear Induced Lift. They're all pulling up on the armrests, knuckles white, and off you go. You have to get some speed and noise first to scare them, that's why you have engines and runway.

On approach you need more passenger fear, so you extend the flaps creating more noise.

Noone has come up with a plausible operation for cargo ops as of yet, but they suspect bumblebees are involved.

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 21, posted (11 years 6 months 6 days 16 hours ago) and read 9143 times:

I thought it was just a bunch of smoke and mirrors. I mean come on how can something that heavy really fly  Wink/being sarcastic It's all a conspiracy. When you board a 747 you don't really fly at all. Special gas is pumped through pressurisation system which induces hullucinations and you then think you're flying. The engines are really only there to make noise.

User currently offlineMiles_mechanic From Canada, joined Sep 2001, 137 posts, RR: 0
Reply 22, posted (11 years 6 months 6 days 16 hours ago) and read 9144 times:

Rick767 made a good point about not being able to tell how fast you are going when up at 37,000 ft. I remember a couple years ago, I was flying on a Northwest 727, and because of the strong head wind the captain decided to keep the plane down lower so the winds weren't so strong since we were a bit late leaving anyway. Well it turned out that at 24,000 ft where he said we were flying, we were just above the tops of the clouds, and at times there were cloud tops at our height. It was amazing how fast those clouds were going by my window when they were just off the wingtip. A very memorable trip.
Miles


User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 23, posted (11 years 6 months 6 days 15 hours ago) and read 9129 times:

+ve Rate,
sssch! You'll blow the chemtrail secret!

The smoke is really in the wires. Think about it. The wires go to the electrical gizmos. When the gizmos break, the smoke comes out and they stop working as they are smoke powered.

Now, this is the thread to give people increased confidence in flying! Big grin

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineBruce From United States of America, joined May 1999, 5067 posts, RR: 15
Reply 24, posted (11 years 6 months 5 days 23 hours ago) and read 9043 times:

I can relate to this thread. When I watch a 747 land, as it is on final approach, it looks like it is moving sooooooooooooooo slow, like it is just hanging there in the sky. A beautiful sight btw. The 737 looks like it is moving much faster.


bruce



Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
25 Beefmoney : Optical illusions can be tricky indeed. Watching a 747-400 come in on approach is always a little adventure for the mind. Looks like its going 30 mph,
26 Positive rate : When i go spotting i usually take my scanner with me and listen in. Normally the planes inbound on the ILS call the tower at 5 miles. From the point w
27 Wardialer : I'll bet I could win a race with a B747 If I was rolling down the runway with my 4 cylinder. seriously speaking. I still think there going at around 8
28 Fritzi : Wardialer, Next time you fly, look out the window during takeoff. If you still think you take off at 80 mph after that, then your an impossible case!
29 Post contains images M717 : Wardlialer, I don't know what else to tell you except you are WRONG. How many times to guys that actually fly the aircraft have to tell you? Apparentl
30 Post contains images FredT : Looking out my window, the earth does look flat. Can't believe how the entire scientific community have gotten this wrong! I bet I could ride right to
31 FSPilot747 : M717, don't waste your time. Wardialer doesn't know squat about aviation. Stick with the non_aviation forum Wardialer. FSP
32 Post contains images M717 : "Wardialer doesn't know squat about aviation." FSP, Evidently, that is the case.
33 XFSUgimpLB41X : Yep..we're all liars. Go race that 747 with your 4 cylinder... get eaten alive. Remember in that video from the 747 the cockpit window's are 50 some o
34 Wardialer : M717, Ok go for it. Give me ALL the lists of rotation speeds. Go right ahead. And im not talking about Airspeed here, Im talking about groundspeed. BT
35 E1FAIL : I drive faster than 80 in my car and the tires hold up just great. BTW, airplane tires have speed ratings.
36 Positive rate : Any rotation speed more than 80 mph or so, WILL blow a tire due to friction and accumalation of heat. Are you having us on dude? Seriously if that's w
37 Scootertrash : IMHO, Wardailer has gone sucker fishing and gotten lots of bites! Easy to do here, what with the normally serious nature of the posts. If he is being
38 Post contains links Ha763 : Straight from the Boeing airport planning manual for the 747, the tire speed limit for the 747 tires is 235 mph (378 kph). See the many graphs showing
39 Wardialer : BTW, why is the take-off speed for the Beech less than the landing speed?? Thats strange, its supposed to be the other way around.
40 Scootertrash : Not necessarily true, Wardailer. When departing, a smaller flap setting (in terms of degrees) is typically used than on landing. The greater flap sett
41 Timz : (Yeah, it looks hopeless, but...) How about this. A heavy 747 will take maybe 7000 feet to rotate, right? Sometimes even more. You think they have acc
42 IMissPiedmont : Wardialer, I thought you died 23 years ago! Fess up, you are indeed my old buddy Don right? The same person who would look at a contrail above and say
43 Post contains links IHadAPheo : I have a few links to the goodyear aviation tire site with more data than you can shake a radar speed gun at http://www.goodyearaviation.com/img/pdf/e
44 AA61hvy : Anyone know how many hamsters it takes to get the 744 off the ground?
45 Post contains images FSPilot747 : Nah just kidding Wardialer. I just figured some of you would get a kick out of that. It was irresistable, sorry. Mods if you find that innappropriate
46 Post contains images Scootertrash : No, No... That is highly appropriate! Not to mention funny as heck!
47 Post contains images Francoflier : Hey, think about it: When you take off from runway 09, you are actually slowing down. The Earth's rotation is pulling the runway from underneath the p
48 Post contains images HAL : Hey, think about it: When you take off from runway 09, you are actually slowing down. The Earth's rotation is pulling the runway from underneath the p
49 Positive rate : Actually taking of on runway 9 you are accelerating because you are heading eastbound, the same direction the earth is turning. If you're taking off o
50 Post contains images FredT : Either way, you are accelerating relative to the earth. Taking off from 27 you are, however, decelerating yourself in a coordinate system fixed to the
51 Post contains images Emem : It's not only the size compared to speed but also angular velocity(=ω ). Looking on planes from a visitors terrace will give the impression of th
52 Francoflier : Yeah, It's the 27, not the 09. I know... But as I told you, I was high at the time... Talking about how fast the Earth surface "goes", it is funny to
53 Growly150 : Also, I have noticed that runways are deceptively wide. So when you are traveling on one in an airplane, it will seem as if you are going slower than
54 Post contains images Jkw777 : Further more, I would like to add the following: Planes do not fly, this is complete crap! How does a 747 get off the ground? It's crap I tell you! Wa
55 Post contains images Fritzi : Justin dude, Congrats on digging up a year old thread which he has eaten up enough already!
56 Post contains images GRZ-AIR : Given the time period in which Wardialer is a member, and the amount of posts he has written, I think someone else has logged into his PC and is writ
57 Post contains images Scootertrash : I cannot believe I just wasted 5 minutes reading this thread... It is sorta like crack, once you start you just can't stop! Or so I've heard, anyway.
58 CitationJet : it's an optical illusion my friend... it has to do with how you brain processes information sent by your eyes. I agree with Aaron, Its just like when
59 CanadianNorth : It may not look fast, but trust me when you give it some throttle todays jetliners can really move. CanadianNorth
60 Post contains images Tbanger : Also, I have noticed that runways are deceptively wide. Yeh but look how short they are!
61 GRZ-AIR : I just don't get it! THIS USELESS THREAD HAS GOTTEN OVER 60! REPLIES! 60 Replies trying to convince someone that airplanes take off at speeds faster
62 Post contains images Starlionblue : GRZ-AIR, haven't you heard? They are now using antigravity generators to assist in takeoff
63 Post contains images Capntoo : Acceleration & tires are not the issue. It's brakes! When you land on a 6700' wide runway which is only 150' long, now you have some serious brake wea
64 Post contains images GRZ-AIR : Antigravity generators? Those are the things attached to the wings right?? Thos funny looking loud things which have that turning stuff inside..just
65 Starlionblue : Those are the impulse engines. The antigravity generators are the flaplike things that extend during takeoff and landing to increase their efficiency.
66 N766UA : Are you serious? 110? That's 20 knots below stall speed even on a regional jet! The bigger jets approach more like 150-170 while the RJs and 737s are
67 7574EVER : Yeap, Its a conspiracy. - Dragogoalie You bet!!! This is right up there with those chemtrails that the government is keeping secret.
68 BartiniMan : With the childish way this guy thinks, I cant believe his parents let him drive no matter what his age. BartiniMan
69 Wbryce : such a stupid topic.... Can't believe this guys going to continue thinking that aircraft take off at these low speeds because he trusts his vision mor
70 Starlionblue : Any good pilot will tell you to trust your instruments more than your senses, or you will end up in trouble.
71 Post contains images Wbryce : Except the fuel guages of course!
72 Starlionblue : And let's not forget tha pilots should ask the pax about their opinions, in case anyone has a useful suggestion...
Top Of Page
Forum Index

This topic is archived and can not be replied to any more.

Printer friendly format

Similar topics:More similar topics...
That Passenger Has Flu And Is Sitting Next To Me posted Sat Nov 5 2005 20:03:37 by Julesmusician
Can Someone Explain Blown Flaps To Me? posted Thu Jun 2 2005 03:53:49 by ZKEYE
What Do 727 T/R Look Like? posted Thu Apr 28 2005 20:34:18 by JAGflyer
Can somebody explain to me what the Localizer is all about? posted Mon Jan 19 2004 08:42:27 by BrodieBrazil
What Do Localizer Antenas Look Like? posted Sun Apr 22 2001 05:45:21 by FP_v2
Flare Or Not To Flare? posted Mon Oct 30 2006 09:58:37 by GlobalVillage
How Does ATC Choose Which Runway To Land On? posted Wed Oct 18 2006 23:24:10 by Fll2993
How Much Space Does A Sea Plane Need To Takeoff? posted Wed Oct 18 2006 22:17:49 by Fll2993
Stored Aircraft - What Does It Take To Un-store posted Mon Jul 24 2006 22:14:13 by Dmanmtl
Why Does The Front-wheel Door Not Close On MD-11? posted Fri Apr 21 2006 00:14:33 by Aero145