Fuel efficiency in headwinds

[Awful_Charlie]

I already did this somewhere in times past:

It's tailored for Bravo PoH figures and UK wind charts, but easily changed. It used Ed Williams aviation formulae, so has macros in it

Put in the wind: (using SW UK in this example)

and the desired track

Read off the best/worst speeds and mpg

 

[Wayne Cease]

3 hours ago, jaylw314 said:

Nice!  I have to say, though, the main reason I started the idea in the first place was to maximize the amount of fuel reserve I had left after a long trip in headwinds rather than the cost savings.  Fuel is cheap, but fuel remaining is priceless...

You'll could get kicked out of the CSOB club saying things like that.   

Look at the data though.  At 30-40 knots of headwind you're not saving much if anything by flying under 75% power.  At 250 nm you're looking at saving 0.72 gallons between 75% and 55% at 30 knots and 0.45 gallons at 40 knots.  For a 750 nm trip you're looking at only 2.16 gallons in 5:20 hours to 1.35 gallons in 6 hours of flying.  That's not a lot added to fuel remaining.  If you're pushing the limits of your reserves, it's important, otherwise not so much.  But if you're pushing those limits, options for a fuel stop (in case the winds are even stronger) is even more important.

I built a distance-time spreadsheet many years ago; right after we came back from a weekend trip into 50+ knot headwinds.  The headwinds were slower at lower altitudes, but also rather turbulent, so we stayed slow and smooth; I didn't need my wife puking on our first weekend flying trip.    We were in a 172 and the spreadsheet showed me a M20J would get back in those headwinds almost as fast as the 172 would arrive with no wind.  I've been making speed a priority ever since.  

 

[ilovecornfields]

Anyone else just use the Mike Busch approach of looking at the fuel totalizer and seeing how much fuel you’ll have when you land and adjusting the red knob to get what you want? I can burn between 10-18 gph at cruise in the Ovation. With “only” the 89 gallon tanks that’s a lot of variability I have when deciding what settings to use. While I like going fast, it’s rarely worth it to burn the extra dinasour juice just to gain a few minutes. 

Unlike some people here, I haven’t solved any partial differential equations since college and I’d rather fly then mess with an excel spreadsheet so the other methods don’t work well for me. I’d rather play with the real numbers in the air than the theoretical ones on the ground.

[Danb]

I do this all the time

[jaylw314]

On 11/14/2018 at 1:54 PM, ilovecornfields said:

Anyone else just use the Mike Busch approach of looking at the fuel totalizer and seeing how much fuel you’ll have when you land and adjusting the red knob to get what you want? I can burn between 10-18 gph at cruise in the Ovation. With “only” the 89 gallon tanks that’s a lot of variability I have when deciding what settings to use. While I like going fast, it’s rarely worth it to burn the extra dinasour juice just to gain a few minutes. 

Unlike some people here, I haven’t solved any partial differential equations since college and I’d rather fly then mess with an excel spreadsheet so the other methods don’t work well for me. I’d rather play with the real numbers in the air than the theoretical ones on the ground.

I can't fly too well when I'm on the toilet 

[201er]

On 11/14/2018 at 1:54 PM, ilovecornfields said:

Anyone else just use the Mike Busch approach of looking at the fuel totalizer and seeing how much fuel you’ll have when you land and adjusting the red knob to get what you want? I can burn between 10-18 gph at cruise in the Ovation. With “only” the 89 gallon tanks that’s a lot of variability I have when deciding what settings to use. While I like going fast, it’s rarely worth it to burn the extra dinasour juice just to gain a few minutes. 

Unlike some people here, I haven’t solved any partial differential equations since college and I’d rather fly then mess with an excel spreadsheet so the other methods don’t work well for me. I’d rather play with the real numbers in the air than the theoretical ones on the ground.

I gotta be flying over 8 hours usually for that to even be a concern.