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Old 8th Feb 2001, 07:29   #1 (permalink)
Retarded Spark
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Post Longest Take-off Run

I just heard on the radio, from a well respected academic (Dr Karl, for the Aussies) that the longest take-off run for an aircraft was by a C-130 Hercules in the Arctic. He says he read it in Air and Space magazine, where asome researchers were being picked up from their station. After loading the aircraft with everything, they attemped to take off but couldn't get off the ground. They lowered the rear door and began offloading equipment, clothing, even computers (minus the hard-drives witht he vital data) before the thing finally got off the ground. Apparently it took 50km. Now I am sure there are more remarkable and unbelievable things out there, but I wonder and ask you who know the Herc better, how long would they have taken to cover this distance at take-off speed? And does anyone have more info, as the details were quite simple due to the broad audience.
 
Old 8th Feb 2001, 08:11   #2 (permalink)
 
Join Date: Oct 1999
Location: Melbourne - Australia
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Imagine if it was a hot day!!!
Lurk R is offline  
Old 8th Feb 2001, 10:34   #3 (permalink)
Retarded Spark
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About the only thing going for them!
 
Old 8th Feb 2001, 10:53   #4 (permalink)
Slasher
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Well its hardly surprising!

* The Earth is an oblate spheriod so its flattened at the Poles. This means the curvature of the Earth couldnt help them

* The Earths cetrifugal force is zero at the Poles, so the Herc weighed more.

 
Old 8th Feb 2001, 14:00   #5 (permalink)
Zeke
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Slasher,

Gravity is a function of the mass and distance between of two objects, not the curvature of the earth, or the centrifugal force. Gravity is the acceleration on the aircraft mass that makes and aircraft weigh something.

The only other factor I can think of (_MAYBE_) is that the exhaust from the engines locally melted some of the ice to get humid air that would stick to the cold aircraft skin giving and increased TOW.

I do not believe 50 km TODR figure at all. In the cold conditions the engines and aircraft would perform well in the dense air, the drag force from the ice runway is not that significant.

Z
 
Old 8th Feb 2001, 18:35   #6 (permalink)
Ultralights
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Red face

Maybee they forgot the release the tiedown blocks!


[This message has been edited by Ultralights (edited 08 February 2001).]
 
Old 8th Feb 2001, 20:15   #7 (permalink)
3holelover
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Obviously the Herc had too much fuel! After 50 clicks at a take-off power setting it finally burned off enough weight. They could've saved a lot of grief by dumping some in the first place. Sounds like the Twotter had the same problem
 
Old 9th Feb 2001, 01:21   #8 (permalink)
Luftwaffle
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When I heard this story, the problem was that the skis stuck to the snow and despite rocking the aircraft and other such trick float/ski pilots use to try and unstick, they just couldn't ovecome the suction to get it off the ice. I remembered the number being closer to 15 km than to fifty, but you can't stop a good story.
 
Old 9th Feb 2001, 08:03   #9 (permalink)
NIMBUS
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Question


50-60km take-off runs, or taxi and T/O?

Tcas Climb,
<<<..About 1hour of this and we sucseeded in getting airborne, we were doing about 35 knots so it was about a 63 kilometer takeoff run..>>
Are you saying you took off at 35 kts?
I know nothing about Otters, but that seems a little low. What's the stall speed?
 
Old 9th Feb 2001, 08:40   #10 (permalink)
Dave Incognito
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Zeke,

while gravity is a function of mass & distance, it also changes with latitude. Closer to the poles, the value is greater than at the equator. For example:

Equator - 9.780 m/s2
Sydney - 9.797
Melbourne - 9.800
Sth. Pole - 9.832

Willing to be corrected, but I believe that this is due to the rotation of the earth and associated centripetal acceleration.

However, rotation of the earth really only affects space vehicles (hence the space launches at Cape Canaveral). This utilises the earths larger orbital velocity nearer the equator.

Oh well, a great story none the less, thanks Dr. Karl & Retarded Spark.

Have a good one, Dave.

------------------
Flying is easy - just throw yourself at the ground and miss.
 
Old 9th Feb 2001, 14:41   #11 (permalink)
gaunty
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Cool

Slasher

Ahhh so that explains why I always seems to use less runway when taking off into the SE.

But then wouldn't Coriolis kick in in the mid lats??
 
Old 9th Feb 2001, 17:07   #12 (permalink)
3holelover
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Ok Tcas, but after an hour at full throttle, you obviously aren't going to have as much as you'd hoped. But, the harder snow north of you wasn't mentioned in your first post.
I wonder if the Herc was a similar thing... Just needed to taxi 50 klicks to get to where there was a better surface... If so, that can't be called a take-off run now can it?
 
Old 9th Feb 2001, 18:57   #13 (permalink)
Squawk 8888
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Dave, you've got part of the picture. The centrifugal force of the earth's rotation does indeed cancel gravity to a minute extent, but it also causes the earth to bulge at the equator. Therefore the surface is closer to the centre of mass at the poles, and as Newton sez gravity increases as the two objects get closer together (the old inverse square rule). And for the rest of you, forget the notion that gravity will increase as you descend a mineshaft- it actually decreases (there is more mass above you and less below) and is zero at the centre of the earth.
 
Old 12th Feb 2001, 08:21   #14 (permalink)
Slasher
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Yeh Gaunty, thats why you need right rudder during TO at the Equator to offset Coriolis!
Hey youd remember Brain & Browns HS Argosy? If there was ever a plane that needed the curvature of the earth to get it airborne, that was the one!
 
Old 12th Feb 2001, 11:05   #15 (permalink)
Zeke
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Dave Incognito,

I would have to agree with Squawk 8888 (even that you cannot select 8 on a transponder)

Gravity reduces with the inversely square with the radius from the center of mass.

As the dist from earths core mass is less to the poles than at the equator the acceleration (gravity) is greater at the poles than at the equator.

The Luftwaffle suggestion of suction conceptually has merit, maybe its something similar to an aquaplaning phenomena. The ice changes state with movement of the aircraft on top giving a change the state of the ice to water or a thin layer of steam causing the earths atmospheric pressure from releasing the skies from the smooth layer of ice below.

Tcas climb thanks for the insight, Vmci…that’s a new one for me !. I don’t know, I just recall the C141 and C130 ops down south not requiring 50 km TORA.

Regards

Z
 
Old 12th Feb 2001, 11:49   #16 (permalink)
gaunty
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Cool

Armstrong Whitworth Argosy.

Yeah I remember when I was livng in Melbourne and working at Essendon used to see a fair bit of them then operated by IPEC.

My son then 5 called it the aeroplane with the big head and 2 tails.

We lived in Mont Albert/Balwyn sorta on track Cowes Plenty and on still nights you could hear the dogs start up some minutes before you could hear the 40 ton dog whistle pass over with the night freight from Tassie.



Check out this site I found whilst trolling for a pic brings back memories of the good old Farnborough days when I used to hang out for the BBC/ABC telecast of the Flying Display.
http://www.aeroplaneart.com.au/Image...gosy_small.jpg
Home page is really interesting too
http://www.aeroplaneart.com.au/
 
Old 12th Feb 2001, 20:31   #17 (permalink)
Slasher
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Yep thats the one Gaunts! But wasnt Armstrong Whitworth taken over by Hawker Siddeley when that 40-ton brick sh*thouse was built?
 
Old 13th Feb 2001, 10:22   #18 (permalink)
ZK-NSJ
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i feel sorry for the poor bugger
who has to go out there with the grader
in below zero temp's and clear the track.
 
Old 13th Feb 2001, 14:58   #19 (permalink)
gaunty
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Slasher
Well we learn something new every day.

You were right Armstrong Whitworth was merged into the HS group in 1935 but retained the name until 1959 when it merged with Bristol Aero Engines to become Bristol Siddley until 1966 it was merged with Rolls Royce.
Prior to all of that they had aquired A V Roe Co Ltd in 1928
Go here for the full very interesting story
http://www.rolls-royce.com/history/history014.htm
Aaaaah all those wonderful old names that were there at the beginning.

Ah James will you bring the motor around please.

Is this a motor or what?

[This message has been edited by gaunty (edited 13 February 2001).]
 
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