flight planning: wind, flight level, route , fuel, time optimum

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Zacke
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flight planning: wind, flight level, route , fuel, time optimum

Post by Zacke »

Hey guys,

I know one could calculate the best flight level or best (alternate) route with given winds aloft, gross weights, performance data and maybe step climb calculations. But in the 40s and 50s did they really calculate that things down to the last numbers or where there some rules of thumb to fly high or low etc.?

An example: I'm planning to go from KBDL to KORF on Thursday early morning. With FL240 headwinds will be around 60 kn and with FL120 the headwinds are somewhere around 30 knots. I know it's a quite short flight and maybe therefore it's not wise to climb to FL240. But let's assume it's a long haul flight and a more general question.
I think at first one should look for the smoothest air for passenger comfort (no turbulence layers, no turbulent clouds, thunderstorms etc.). Aside these aspects where would you choose your flightlevel for fuel and time economy? Flying high for the highest TAS or flying lower for avoiding that strong headwings?

I watched a Lufthansa Super Star (Lockheed L-1649) promo where they flew from Hamburg to New York City and said the flightlevel will be 4000m (=13.000 ft). For sure that was for avoiding the jetstream over the atlantic.

I know it's a complicated question but maybe there's a more or less short and pragmatic way to handle this problem.

Thanks in advance,
Zacke

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Paughco
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Paughco »

One way is to prepare your flight plan with SkyVector. Click on the Layers link on the upper right of the window, and select wind barbs. You can then click on the little gear symbol to vary the altitude of the wind barbs to see what's happening at various altitudes and forecast times. Adjust altitude and/or route to optimize winds enroute.

Seeya
ATB
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flapman
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by flapman »

Zacke wrote: 29 Sep 2020, 07:39But in the 40s and 50s did they really calculate that things down to the last numbers or where there some rules of thumb to fly high or low etc.?
They calculated to the "last numbers" with the best data they could reasonably get hold of. The rule of thumb is to choose the altitude that makes those numbers the best.
But let's assume it's a long haul flight and a more general question.
I think at first one should look for the smoothest air for passenger comfort (no turbulence layers, no turbulent clouds, thunderstorms etc.). Aside these aspects where would you choose your flightlevel for fuel and time economy? Flying high for the highest TAS or flying lower for avoiding that strong headwings?
Fly at the altitude at which you can safely maximize your Groundspeed for a given KIAS (and power setting).
I watched a Lufthansa Super Star (Lockheed L-1649) promo where they flew from Hamburg to New York City and said the flightlevel will be 4000m (=13.000 ft). For sure that was for avoiding the jetstream over the atlantic.
Possibly. They might also have been extremely heavy and couldn't climb higher. They may have also step climbed over the many hours of that flight.

As you said, the answer can get quite complicated. :D

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MkIV Hvd
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by MkIV Hvd »

Paughco wrote: 29 Sep 2020, 11:12 One way is to prepare your flight plan with SkyVector. Click on the Layers link on the upper right of the window, and select wind barbs. You can then click on the little gear symbol to vary the altitude of the wind barbs to see what's happening at various altitudes and forecast times. Adjust altitude and/or route to optimize winds enroute.

Seeya
ATB
Well there's something very cool about Skyvector (which I use on every flight ;)) that I did not know. Thanks for mentioning that Paughco!

Cheers,
Rob
Rob Wilkinson
A2A: Civilian Mustang, T-6, Bonanza, Comanche, Cub, C182, Spitfire, P-40, Cherokee, P-51 - VATSIM P4 and some other stuff...

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Jacques
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Jacques »

In the very back of the manual is a cruise schedule chart that provides guidance for answering your question. As always you will need to play around with your payload, altitude, mixture and power settings to best suit your needs.

Zacke
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Zacke »

Thanks for your fast responses.

@ Paughco: Yes, I alway use skyvector for flight planning and know the wind options. There I get my wind data mentioned above from. But as far as I understand skyvector has only the aircraft performance for one given cruise profile (in my case for FL240) and does use it even if you're planning for FL120. That's my problem. ;) Maybe the best way would be to test the Connie for all kind of performance values with different FL and so on and then create different aircraft profiles within skyvector. Then you could check out quite fast which FL would be best (ignoring different OATs, weights etc. ;))

@ Jacques: Yes, I've seen that schedule in the manual but I always cruise with much lower engine settings for endurance and noise reduction reasons: 1600 rpm/27 MP. That schedule is missing different power output levels.

Zacke
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Zacke »

By the way: I think the weather and winds aloft forecast of the 40's and 50's must have been much (!) weaker than today. A relatively thin network of balloon sondes, especially over oceans. Maybe the main source were reports from other aircraft which calculated winds aloft "on the run" and in a tight schedule for the main routes.

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Jacques
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Jacques »

Hey Zacke, try this link https://ww2aircraft.net/forum/threads/l ... ual.22092/ for the C-69 manual...some of the charts in the back may lead to more ideas for cruise profiles. Its the military version so you might not find much for cruising above 15.000’.

Zacke
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Zacke »

Thanks for the link. Good stuff! What a pitty they're only up to 15000 ft.

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Jacques
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Re: flight planning: wind, flight level, route , fuel, time optimum

Post by Jacques »

Yes, it would be a bit like Christmas to find a manual for the early civilian Constellation! :D

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