trivial trivia

[alpha2]

Hint: It's related to "groundspeed".

[bermudahwin]

24 minutes ago, alpha2 said:

Hint: It's related to "groundspeed".

If it was 100 mph  over 100 miles each way with a 10 mph wind the return journey will be quicker than the outward. The total time 2.02 hrs

If there were no wind each trip would be 1 hr each way totlalling 2.00 hrs.

I think... it was calculation number 50 or 60 and my head hurts.

Harry

 

 

[alpha2]

You got the idea. Basically, you spent LONGER going at a slower groundspeed. You spend a noticeably shorter time going faster. More time at 110 kts groundspeed, less time at 90 kts groundspeed.  

I think I only had one student get it right the first time. It's critical, though, as in airplanes, you don't burn miles per gallon, you burn hours per gallon. "Time in your tanks" was the rule.

Jeff

[bermudahwin]

Loads of wasted paper...

I had the feel of it but the maths eluded me, logically I cannot work out if the time was "made up" or not.

H

[alpha2]

You can only make up the time, if the time spent at the two different groundspeeds were the same, but you spent more time at the slower ground speed to cover the fixed distance, and less time at the higher groundspeed over the same distance. Can't make it up. The students always fell into the "groundspeed vs. airspeed" thing. They always figured if your airspeed was the same, you could make it up. Your groundspeed into the wind was 90kts, (100kt airpspeed, minus the 10kt headwind). Return trip, same 100kt airspeed, but 110kt groundspeed. (100kt airspeed plus 10kt tailwind.)

FYI, your time enroute into wind would be around 1:07, and time back would be around :54.

We aren't even getting into density altitude and True vs. Indicated airspeed. Yeah, ground school is a bitch.

Jeff

[Mjolnir]

so how fast are you really going in relation to earths rotation and universal expansion?

[alpha2]

Universal expansion is unclear, as recently it was discovered that as opposed to the universal expansion slowing, as most thought, it was continuing to accelerate. Big shock, so I won't address that.

However, your "airspeed" will be the same. But, there is Coriolis effect. And the effect of that will be different depending on latitude and direction of flight.

It's not just aviation that's affected by Coriolis. Long distance shooting must take it into consideration. Even over 1000yds the impact point on target will be different if firing position is reversed with target location. (Not much, but still...). The field artillery guys take it into account.

Jeff

[alpha2]

One more thing, there is a reason rocket launches into space are done as close to the equator as possible. Earth rotation gives them a head start for picking up orbital speed.

[bermudahwin]

@alpha2 Dang it to heck I was a minute out, but still don't fully understand why.

@Mjolnir the math is a bit questionable, but Monty Python sang the Galaxy Song, which explained it to me.

 

 

 

[Mjolnir]

32 minutes ago, alpha2 said:

Universal expansion is unclear, as recently it was discovered that as opposed to the universal expansion slowing, as most thought, it was continuing to accelerate. Big shock, so I won't address that.

However, your "airspeed" will be the same. But, there is Coriolis effect. And the effect of that will be different depending on latitude and direction of flight.

It's not just aviation that's affected by Coriolis. Long distance shooting must take it into consideration. Even over 1000yds the impact point on target will be different if firing position is reversed with target location. (Not much, but still...). The field artillery guys take it into account.

Jeff

yep. you just explained  why toilets in Australia flush counterclockwise.