Relative fuel consumption

[dick56]

In the northern Hemisphere the wind direction rotate clockwise from the ground up to about 55,000 feet. Above around 55,000 feet there is no wind.

When the SR-71 was cruising at 85,000 feet, they never worried what the wind was as there was none. From Area 51 after breakfast to Eglin Air Force base in Florida, it was 55 minutes and it was 55 minutes back to Area 51, but first you had to do a 258 mile radius turn over the Atlantic to turn around at Mach 3.2. Then you had to descend to around 28,000 feet to get enough fuel from a tanker to get back west and land in time for lunch. Quite a mornings work!

 

[dick56]

I just took a look at the average ground speed taken from my Garmin Navigator of my Cessna 340. After 401 hours of flying, the average ground speed was 169.1 knots. The 340 cruises at 200 to 210 knots true airspeed. Most of my flights are above 18,000 feet, but time to climb can be as much as 28 minutes at 130 knots, and you add in headwinds and crosswinds and sometimes tailwinds and it averages out to 169 knots after 400 hours. The highest speed recorded was 314 knots groundspeed, but not much of that. Attached is a screen shot from the navigator of the 314 speed run.
Desert Flyer

 

[fliger747]

Back to the first entry of this thread, a tail wind will not affect the climb, nor will a headwind once you are on course in a steady ascent. The only thing important to the plane is the IAS for a given weight and temperature. However the ground speed will be affected and hence the angle of the climb as plotted across the ground.

 

[gumbyk]

Back to the first entry of this thread, a tail wind will not affect the climb, nor will a headwind once you are on course in a steady ascent. The only thing important to the plane is the IAS for a given weight and temperature. However the ground speed will be affected and hence the angle of the climb as plotted across the ground.

That's true for a one-way trip. If you have to turn around and come back, the loss of performance due to the headwind on the return trip outweighs the increase of the outbound trip.

 

[fliger747]

It's true for any airplane at any time.