Annual winds LBV-IAH

[OverRun]

I'm looking for the Boeing 85% Annual Winds as I study the economics of a route from West Africa to USA: Libreville to Houston (LBV – IAH), for a simple great circle track. FL370.

My experience with winds is limited to the southern Hemisphere, and this type of equatorial route is outside my experience. Naturally this is not for flight planning, aircraft dispatch, airborne flight navigation, or any other type of actual flight operation.

Cheers
OverRun

[mutt]

Be careful about using average annual winds as they usually dont reflect the higher winter winds. Suggest you break it down into quarters. You can use Boeings winds software or a flight planning system like Jeppesen.

Good Luck

Mutt

[OverRun]

Thanks Mutt - good advice on the seasons and gratefully noted. Let me follow up Jeppesen.

[enicalyth]

I have some data arranged in the four seasonal quarters but it is part of a very large pdf and you woulfd have to engineer it a bit because it is based on city pairs of which Libreville-Houston is not one. You would therefore have to jiggle it into segments of suitable city pairs.

It gives outbound and inbound winds for the 700, 500, 300, 200, 150 and 100mb pressure levels for the four seasons based on 50% occasions but incorporates a conversion table to suit the percentage occasion you want based on the standard deviation.

I could send you a disk. It would be from an expired Airac Cycle and if you attemopted to autorun it then a big red warning would disallow access.... but if you just click of the drive and select "Explore" it allows you in.

Methinks post is best in this case. Oh, and it does the same for temperatures as it does for winds.


PS - Hang on Prof! I'm a stuffwit!! I have just realised I can "print" the selected pages from the pdf into an mdi file. mdi is the microsoft document image format and it loses a bit of resolution but is readable and is only 1151 kilobytes. If you don't have mdi on your PC it is downloadable as a freebie from microsoft. I can wing it on its way right now. Also, what is doing the flying? I might, just might, be able to do something else too, depending on which letter of the alphabet it begins with.

Best rgds

The "E"

[OverRun]

enicalyth,

That would be really great. PM on its way.

:ok:
Overrun

[OverRun]

It really has been appreciated. Let me give some feedback on the winds issue for the interest of anyone following this topic.

Mutt made the point about the winds varying by season, and suggested I break it down into quarters.

I have got the results from a flight planning system for the route and they show clearly the difference that the varying seasonal winds make (there was a different routing each season to minimise the effect of headwinds); this is for a B777 and using 85% reliability historic winds:

Jan-Mar
Headwind 39 knots. Fuel needed 98,167 kgs. Flight time 15:05.

Apr-Jun
Headwind 38 knots. Fuel needed 92,073 kgs. Flight time 14:23.

Jul-Sep
Headwind 8 knots. Fuel needed 85,220 kgs. Flight time 13:29.

Oct-Dec
Headwind 42 knots. Fuel needed 93,989 kgs. Flight time 14:39.

Not for operational use of course, and I am reminded that Murphy's Law would mean that the first time when this is done for real, the winds would be at 99% of historical values not 85% . . . . . . :)

[enicalyth]

Prof, G'Day

Look also at Dakar-Sal Amilcar, Bermuda-Miami, Miami-Mexico City, Windhoek-Luanda.

Just sent you a zip of something else and if it is useful let me know. There is more.

Waving my paw in your general direction, stubby in the other, feet resting on the dog. Actually it's stubby in the dog, dog on my lap, phone ringing...

Best Rgds

The "E"

[OverRun]

Hi enicalyth,

Legs noted – thanks for that as I navigate my way through various tables, and I can sensibly put together the various legs.

And I've got the zip file now, and am playing it now. Really great stuff, and the ability to play with various values is superb. As they say in Libreville 'profitez de la bière fraîche, et vont bien mon ami'


Overrun

[enicalyth]

My header says it all about the zip file. Those of my own files that are not on the zip file are licensed to me but I am not averse to running some stuff for you on, say the B777, and using the sendit facility. Direct me as you please. Or you might wish to purchase a licence from the originator. These are not inexpensive, singly per aircraft model, but across a wide range of aircraft it does become expensive.

I wish I had had access to this sort of stuff years ago. I note with very much interest your figures given above and will, with your permission, run off some analyses. probably this week-end if that's OK?

I only know one French pun... traduisez "Je bis a vore" ?? Ecoutez bien, "Je bois, sans "oh", a votre sans "t"... or je bois a votre sante, mon ami

Still waving a paw gently in your direction

The "E"

[OverRun]

Hi enicalyth,

A 777 analysis would be great for the -300ER. I have some of my own models set up and running now which I have been calibrating against the data I've received and they are making sense for those few aircraft types, which (lucky dog) includes the 777-200LR and that is the aircraft I mentioned above. If you get the chance to take a look this weekend, I'd be very grateful. I've been previously using the BADA files for fuel consumption and there is something not quite logical about their 777-200 and -300 fuel consumptions; almost as if they are reversed. Hence I'm not quite sure about the -300ER.

And many thanks for the SENDIT performance data for the A319 operation. Since the A319 is something I was looking at for regional flights, and of interest, the CAA reserve fuel policies were something new to me for the isolated airport case:

Reserve fuel policy for normal CAA profile
En-route allowance : 5% of trip fuel and diversion fuel
Diversion to the diversion airport at LRC
30 min holding at 1500 ft above alternate

Reserve fuel policy for CAA profile isolated airport
En-route allowance : 5% of trip fuel and diversion fuel
Diversion reserve : continued cruise for 120 mn
30 min holding at 1500 ft above destination

You win on the French puns. My best is:
Q. What happened when the three kittens fell in the swimming pool?
A. Un deux trois quatre cinq.

Cheers
Overrun

[enicalyth]

The trouble with websites is that we speak tersely and Prof and I being both consulting engineers don't have to spell out code of conduct.

My EULA with Jeppesen Weathertext does not preclude me from running a demo and showing it to another. I may not of course allow that other to use my terminal or my login. And if Prof likes the look of a finished article he can buy his own licence.

Likewise I use Digital Atmosphere for which I have a registered version. I have sent the Prof the same weather tables anyone can get scot free by writing to Bracknell. I propose to manually enter that W+T data in the correct format into DA and let it draw me weather maps. If he likes the finished article, he can buy a licence.

As for Boeing and Airbus Airport Technology... well tables of range, pavement loading etc are published free by one company and on authorisation by the other at reasonable cost.

I apologise for any seeming asperity but really you must think of the learned Prof and myself as gimcrack spives knocking up a dodgy runway design. Being retired and getting on it’s a rather funny image.

Prof has a very public face, website and all. Me I am an elderly retired gent, thirty years flying and eking out my coffin dodging years by being pleasant, helpful but very correct and playing strictly by the rules. There are on this very site a very long list of very respectable and internationally recognised men and women who can confirm as much.

So I'd appreciate it on my behalf and that of the Prof if you would withdraw your post as its seems to imply that we are a pair of shonky spivs. We do know how to behave and how to respect intellectual property and if you had read any one of my many posts on that very subject, you'd realise that any imputation to the contrary is unjust

All the best

"E"



All the Best

The "E"

[Compaero]

enicalyth,
If you played by the rules I am more than happy to apologise. Post withdrawn in any case. I would recommend taking some care in sentences that include the word 'licence' in a forum, it's like bomb jokes at the check-in queue. And no, I don't see you as any shonky spiv at all.

[OverRun]

Compaero,

Enicalyth has comprehensively addressed what we haven’t done, and I thank him for that.

What I might do is to spell out what we have done. I have benefited from the winds for LBV-IAH plus a deal of peripheral knowledge, and for Tech Log and the readers of PPRUNE, we have left an educational and knowledge legacy of:


The winds LBV-IAH.
Since these can be extrapolated a bit (within limits), a look at winds for any crossing from West/Central Africa to the lower USA, and of course from the lower USA to West/Central Africa.
A discussion on how a route can be built up from suitable city pairs.
A look at the long range fuel consumption of the big jets in kg/hour – in this case the 777.
Quantitative illustration of the variability of winds through the year.
Shown that the fuel load of a 777 on this route can vary by up to 13 tonnes depending on season.
For the general reader, a peek into the world of route and flight planning.
For the ATPL holder or student, and after their simple calculation of great circle distance LBV-IAH with the application of CAP697 on flight planning, enough to let them experiment with NAM and NGM on the route.
A subtle warning to the professionals that the BADA 777 fuel consumption tables need a bit of care.
Shown the CAA reserve fuel policy requirements, and the particular requirements for an isolated airport, which may just help someone avoid running out of fuel one day (such as MMA MacRobertson Miller Airlines Flight MH 372 Broome-Derby, Western Australia, Australia - July 30, 1971, VH-FKC: During the short late night hop both originating and destination airports became socked in with fog. The F-28 became dangerously low on fuel and after circling for some time the captain was preparing to ditch in the ocean. However local knowledge plus an alert Flight Service Officer got kerosene flares laid on the dirt strip at Fitzroy Crossing, and they landed, running out of fuel as the jet touched down. No lives lost or injuries occurred. In times after, I recall discussions with Ansett (who took over MMA) who operationally treated these ports at night as isolated airports).
And some French puns.


Which is doing pretty much what Tech Log does – helping and teaching people. And that is why we spend many hours making our contributions. The forum is open for all to contribute. I would suspect that you have interesting knowledge, possibly from work on Piano, and your own technical contributions and additions to knowledge would be most welcome here.

Cheers
OverRun

[Compaero]

OverRun (and E),

All points noted and understood. For the record, I consider this an excellent forum for some all-important 'ground truths' and that is why I take an occasional look-in, although I rarely log-in (and given time pressures and other considerations may not be able to contribute). What is done here is good (after the inevitable chaff of any open forum is mentally filtered). Regards.

[mathy]

JBut jst in case readers do not know go to http://www.boeing.com/commercial/airports/acaps/777_2lr3er.pdf

I am a bit shocked at Overrun's figures though. The cruise portion route cannot be shorter than 5950nm in still air in my estimation. With the slighest headwind at 8kts that makes a cruise ground speed of 467kts.

I won't trouble to go on with the rest of the calculations but that is a pretty mean route when it goes windy.

352 tonnes weight Overrun?

[mutt]

I am a bit shocked at Overrun's figures though Why? What do you find surprising about them? I have a good idea of where they came from and they are real life figures.

Mutt

[OverRun]

Hi mathy,

Not 352 tonnes – well below that for this route. The passenger load is much less than some would expect. I've seen a few people do these analyses based on maximum passenger capacity which for the 777 can be anything from 305 to 550 pax. In service though, the airline seat fit can be much less than this, and my pax numbers are based on an actual airline and they are fitted for below 300 in a 3 class layout. And the cargo load is low for this route. And the fuel load is quite a bit less than maximum. It all adds up, and this operation is planned at some 50 tonnes lighter than MTOW.

For me, looking at the runway, it makes quite a difference. There is something in this which is a lesson to airport engineers and perhaps some pilots as well. Forgive me if I speak in simple terms – I am used to explaining this to governments and airports and they need it being kept simple. In the old days, inter-continental operations meant long runways – 3500m was a typical figure, and more if the runway was at elevation or in a hot place. Johannesburg is up to 4390m long. I took a look at a runway last week for another very high and warmish country, and the first pass come out at 5000 metres which is too long for the tyre temperature limits. I have a simplistic rule of thumb that tyres tend to blow at about 4500m on the takeoff run – not scientific but it alerts me to check it properly if I am close.

The outstanding performance of the modern twins has changed some of the rules of the game in terms of runway length. The aircraft that go an ultra-long distance need a lot of fuel just to be able to carry ALL the fuel required for the flight. The engines are massively up-sized so they can haul the whole lot off the ground on just one engine. When those aircraft operate on a somewhat shorter route, then the drop in fuel load needed is significant but the massive engines are still there. The takeoff performance is nothing short of astonishing (without de-rate), and inter-continental operations can easily take place off short 2500m or 2700m runways.

Cheers
Overrun
PS - and I share Mutt's confidence in the figures

[mathy]

Hello Overrun and Mutt

I begin to see more sense.

Is it more like this?

Cd0 = 0.01300 typical
Cdi = CL^2/24.38
Cdc = 0.0015 typical
OEW =168.0 tonnes.
Payload = 250.0 tonnes
ZFW = 193.0 tonnes
LDW = 203.0 tonnes
TOD = 204.0 tonnes
TOC = 294.5 tonnes
TOW = 301.0 tonnes
GS = 442.5kts
tsfc = 0.55,kg/kg-hr,
L/D = 20.2 typical average
Climb 122nm
Cruise 5968nm
Descent 130nm
Total 6220nm
Trip fuel = 98 tonnes
Trip time = 14.4hrs


The wing would have to have an aspect ratio of 8.7 and an Oswald's "e" of 0.89 for example.

Anyway nice talking to you

Mathy