Boeing 787 Aerodynamic Report

[RobertSmalls]

Originally Posted by Old Mechanic

Good to hear from you Robert. For a while I though the aliens had taken you to another planet.

regards
Mech

Nope, my mind is still intact. I've just been satisfying my engineering cravings at work and elsewhere. But it's nice to see posts from the familiar faces here again.

@kach: It's a shame, but one of the reasons cities like London and New York have such good subway systems and walkability is that travelling by car is so terrible. If you build better highways or raise speed limits, people aren't going to spend any less time driving to work, they're just going to live farther away. That's why I'm not so sad that efficiency improvements like the "air taxi" died last decade.

Originally Posted by tortoise

The aerodynamic drag of ten Insights going 560 mph, that is. (Wouldn't that be fun?)

I believe drag coefficents on aircraft are calculated using area in plan view (from above or below) rather than frontal area.

Drag coefficients for cars, fish, and aircraft use different reference areas, but Cd*A is still comparable.

Ten Insights going 560 mph at 37000ft. That would be fun. Everyone would need supplemental oxygen, though. Air density is a quarter of what it is at sea level.

Suppose an Insight gets 75mpg at 68mph. Suppose it were driving at the above altitude and speed, ignoring a while slew of problems with the idea. Aerodynamic drag is proportial to speed squared times density, so it would be 16 times greater at 560mph. You burn fuel 16 times as fast, but cover ground 8 times as fast. Therefore, you'd be getting around 38mpg.

@TVago: People who spend their money as they see fit often buy destructive things, like gasoline. Doing whatever you want with your money is your right. However, acting without regard to the impact of your actions on others is, at best, childish. We can do better.

[t vago]

Originally Posted by RobertSmalls

@TVago: People who spend their money as they see fit often buy destructive things, like gasoline. Doing whatever you want with your money is your right. However, acting without regard to the impact of your actions on others is, at best, childish. We can do better.

Sure we can.

People who spend their own money as they see fit often buy destructive things, it is true. People who spend other people's money as they see fit are just as destructive, if not more. And speaking of destructiveness, which is more destructive for a hypothetical 1 hour plane/5 hour car trip?

You know, looking back at the first post, it's really easy to just look at the gas mileage of a 787 vs a Prius and conclude that that cross-country travelling family of 5 is wasteful. 15 hours to drive cross-country in a Prius? Oh, sure! It took me 40 hours to drive cross-country once, and I was single back then! How will that family escape being caught for speeding bordering on criminal recklessness? You do know that they'd have to be travelling an average of 190 MPH to make that 15 hour trip length, right? What will the kids pee in? An empty bottle that they pour out the window? How about stops for food at, er, interesting places? How about construction delays? How about those other factors I mentioned? Let's pray to God that that family of 5 doesn't get broadsided by some texting-and-driving jerk.

...And that's my point. There are more things than are dreamt of in your fuel economy universe.

[GRU]

and there is no risk in flying!? stop trying to make flying look great, there are plenty of bad things that come with flying but i was trying to say it's not worth taking a 1 hour trip with a plane. it all depends on the situation but in most cases a 1 hour flight will cover around 300 miles. If you're going more than 600 miles i wouldn't even think about driving

[mechman600]

Originally Posted by GRU

agreed, sometimes i wonder why people brag about taking 1 hour flight which took 5 hours total to get from point A to point B when they could have just taken their car for a 4 hour trip and eliminated the process of checking baggage, waiting on the plane and airport, taxi and other things involved when flying.

I agree. Drive to the airport (or drop your car off at a friend's house and have him/her drive you to the airport) - 1/2 hr, check in - 1/4 hr, wait - 3/4 hr, get on the plane and wait - 1/2 hr, fly, wait for bags - 1/2 hr, rent your ride - 1/2 hr, drive to your destination -1/2 hr. That's another 3-1/2 hrs on top of the actual flight. If it's a short flight, I would rather drive myself, even if it takes a couple of hours longer. I can listen to my own music, see some scenery, relax and breathe non-stuffy air.

Unfortunately, anywhere I go more than an hour away is over huge, massive mountains with twisty roads where a plane has even more of a speed advantage. However, those roads are ridiculously fun to drive....

[jamesqf]

Originally Posted by mechman600

Drive to the airport (or drop your car off at a friend's house and have him/her drive you to the airport) - 1/2 hr, check in - 1/4 hr, wait - 3/4 hr, get on the plane and wait - 1/2 hr, fly, wait for bags - 1/2 hr, rent your ride - 1/2 hr, drive to your destination -1/2 hr. That's another 3-1/2 hrs on top of the actual flight.

And who's being an effing optimist now? My own experience (extrapolated a bit since I haven't flown commercial since they instituted the TSA):

Get to airport: about 1 hour from home.

Check in & security: 1-2 hours, minimum.
(Understandable reactions to security: anything from going home to jail time.)

Waiting for next flight 'cause the one you were scheduled for either was canceled, is overbooked, or has already left: about 1 in 5 chance of delay up to 8 hours.

Boarding & taxiing: 1/2 hour or more. 2 hours if you happen to be departing Dallas and there are tornados sighted - and isn't an airplane sitting on a taxiway a FUN place to wait for a tornado to hit?

Sitting on the ground for hours at a small airport in Iowa 'cause Chicago (where you're supposed to catch your connecting flight to London) is shut down due to T-storms.
Finally arriving in Chicago to discover your connecting flight has left. Having airline people tell you you can get on another flight leaving from a different terminal. Spending 1/2 hour getting to other terminal, only to find that flight has left. Airplane people say oh, the next one is back at the gate you started from, better hurry.

Arriving, wait an hour for bags. In Geneva discover your luggage is in Brussels, or maybe Moscow. Arriving home, find your luggage is somewhere, probably, but not here.

Then there are the pleasures of air travel itself: getting to sit between two obese people, having the guy in front recline his seat while your tray's down, having the people with the squalling infant in the next row decide to change its diaper in their seats...

[tortoise]

I believe the intent of the OP was to celebrate the advanced engineering of the 787, to inspire us to make comparable improvements in our cars, not to persuade us to fly.

[kingsway]

I think it is commendable to try and be economical in our consumption of fossil fuels. But lets not forget that it is our use of these fuels that has made our lives hugely more enjoyable, productive and long...

To go back to self-sufficiency would be to go back to short lives of great labour and drudgery!

By all means lets try to increase efficiency and reduce waste - but lets not take too much notice of the people who all scream 'doom and gloom' and predict the imminent and disastrous collapse of civilization as we know it!

All the previous predictions have been wrong....

[mwebb]

Originally Posted by kingsway

I think it is commendable to try and be economical in our consumption of fossil fuels. But lets not forget that it is our use of these fuels that has made our lives hugely more enjoyable, productive and long...

To go back to self-sufficiency would be to go back to short lives of great labour and drudgery!

By all means lets try to increase efficiency and reduce waste - but lets not take too much notice of the people who all scream 'doom and gloom' and predict the imminent and disastrous collapse of civilization as we know it!

All the previous predictions have been wrong....

the event has already happened , "they" were right -
those who can not see it
are very much
in denial
and will not survive what will follow , shortly

[hamsterpower]

Originally Posted by Cd

As we would near our destinations , I could hear the pilot lower the gear despite being ten minutes away away from landing. I could literally feel the drag pulling the plane .

I'm sure there is a safety related reason for lowering the gear several miles away from the airport, but it still makes me cringe every time it happens.

Yes and that safety reason is so the airplane can go from 500~MPH and 30K feet to 180~MPH and airport elevation. It's really hard to land at cruise speed.

[kingsway]

Originally Posted by mwebb

the event has already happened , "they" were right -
those who can not see it
are very much
in denial
and will not survive what will follow , shortly

You sound very much like one of those prophets of doom! Do you really know something we don't??

Just in case you are still open to considering an alternative view....
Rational Optimist*-*Matt Ridley

It is fashionable, and 'cool' to be pessimistic - but we humans have survived a long time by continuing to change and adapt... Never in the history of the planet have so many people been more affluent and healthy than they are now, and the improvements still keep coming!