Report Card for Donald Trump

[David Horn]

(01-16-2017, 01:13 PM)SomeGuy Wrote:

Warren Dew Wrote:Supersonic flight is not inherently less fuel efficient on a per mile basis, just on a per hour basis.

Yes, it is.  Fuel use is largely a function drag, and drag is a function of speed.  In addition, the drag coefficient increases significantly after about Mach 0.8, pushing up fuel consumption dramatically.

It's not that it is impossible to fly past the sound barrier, I just question whether it is possible to do so cheaply.

But what would I know?

The only model that's even reasonably fuel efficient is the semi-ballistic model, that involves near-space flight during most of the trip.  Essentially shooting the vehicle into sub-orbit using a rail launcher, and more-or-less coasting in for a landing seems a bit extreme for all but the truly adventurous.  I don't see it, but it seems possible.

[Warren Dew]

(01-16-2017, 01:13 PM)SomeGuy Wrote:

Quote:Branson has been trying to provide supersonic service for some time; he tried to buy the remaining Concordes from British Air when British Air stopped flying them when the internet bubble burst.  That's why I view this as credible.  This company is connected to his Space Ship One venture, which is less likely actually to offer paid service, but which has relevant technology.

Don't get me wrong, I think all that stuff is cool, but I wonder what technology you'd think Space Ship One has that would translate into affordable supersonic commercial jets?

Composite materials suitable for the high temperatures of supersonic applications.

Actually this is interesting for another reason:  aerospace composites are a new technology, and Boeing already has a worldwide lead in them.  Since engineering is being done by a US team for this, it extends the US technology lead.  This is the kind of manufacturing I think the US can usefully emphasize:  emerging technologies where the US has a technical lead thanks to our strong University network.

Quote:

Quote:Supersonic flight is not inherently less fuel efficient on a per mile basis, just on a per hour basis.

Yes, it is.  Fuel use is largely a function drag, and drag is a function of speed.  In addition, the drag coefficient increases significantly after about Mach 0.8, pushing up fuel consumption dramatically.

It's not that it is impossible to fly past the sound barrier, I just question whether it is possible to do so cheaply.

But what would I know?

It's not that simple.  Drag coefficient increases substantially right at the sound barrier.  However, it then falls again at higher speeds.



If you're cruising at mach 2 or above, there's no fundamental reason why fuel economy has to be worse for supersonic flight.  There are differences due to much more research and development money being spent on optimizing engines for subsonic fuel efficiency, but that just means we ought to expect rapid improvement once fuel efficiency becomes a focus for supersonic engines.

[SomeGuy]

Quote:What you quoted was what I thought.  Comparative advantage held in Ricardo's day because capitalists were leery of investing abroad for fear their property being confiscated by foreign governments (e.g. investment made in imperial Russia before 1917 or American oversea capital assets that were nationalized by socialist governments after WW II). 

Well, I don't think Ricardo was really worried about Communist expropriation at the time.  There is that, but also that a sole proprietor would actually have to move to a different country and culture, which is what he was talking about in the quote I provided.

Quote:What I was asking about was the silly thing to which you referred.

Remind me.  What "silly thing"?

[Mikebert]

(01-16-2017, 03:03 PM)Warren Dew Wrote:

(01-16-2017, 01:13 PM)SomeGuy Wrote:

Quote:Branson has been trying to provide supersonic service for some time; he tried to buy the remaining Concordes from British Air when British Air stopped flying them when the internet bubble burst.  That's why I view this as credible.  This company is connected to his Space Ship One venture, which is less likely actually to offer paid service, but which has relevant technology.

Don't get me wrong, I think all that stuff is cool, but I wonder what technology you'd think Space Ship One has that would translate into affordable supersonic commercial jets?

Composite materials suitable for the high temperatures of supersonic applications.

Actually this is interesting for another reason:  aerospace composites are a new technology, and Boeing already has a worldwide lead in them.  Since engineering is being done by a US team for this, it extends the US technology lead.  This is the kind of manufacturing I think the US can usefully emphasize:  emerging technologies where the US has a technical lead thanks to our strong University network.

Quote:

Quote:Supersonic flight is not inherently less fuel efficient on a per mile basis, just on a per hour basis.

Yes, it is.  Fuel use is largely a function drag, and drag is a function of speed.  In addition, the drag coefficient increases significantly after about Mach 0.8, pushing up fuel consumption dramatically.

It's not that it is impossible to fly past the sound barrier, I just question whether it is possible to do so cheaply.

But what would I know?

It's not that simple.  Drag coefficient increases substantially right at the sound barrier.  However, it then falls again at higher speeds.



If you're cruising at mach 2 or above, there's no fundamental reason why fuel economy has to be worse for supersonic flight.  There are differences due to much more research and development money being spent on optimizing engines for subsonic fuel efficiency, but that just means we ought to expect rapid improvement once fuel efficiency becomes a focus for supersonic engines.

Um yeah there is.  You are showing a plot of drag coefficient CD.  Drag force is proportion to CD and speed squared. Since work is force integrated over distance, fuel economy (i.e. work per distance) would be correlated with drag force.  So even if CD returns to its subsonic values, fuel economy at 1500 mph would still be nine times less than at 500 mph.

[SomeGuy]

(01-16-2017, 02:56 PM)David Horn Wrote:

(01-16-2017, 01:13 PM)SomeGuy Wrote:

Warren Dew Wrote:Supersonic flight is not inherently less fuel efficient on a per mile basis, just on a per hour basis.

Yes, it is.  Fuel use is largely a function drag, and drag is a function of speed.  In addition, the drag coefficient increases significantly after about Mach 0.8, pushing up fuel consumption dramatically.

It's not that it is impossible to fly past the sound barrier, I just question whether it is possible to do so cheaply.

But what would I know?

The only model that's even reasonably fuel efficient is the semi-ballistic model, that involves near-space flight during most of the trip.  Essentially shooting the vehicle into sub-orbit using a rail launcher, and more-or-less coasting in for a landing seems a bit extreme for all but the truly adventurous.  I don't see it, but it seems possible.

Which, you know, would look an awful lot like a ballistic missile launch on the radar.  I am sure you could work out institutional arrangements, but I'm not seeing it as a routine mode of transportation.  A lot still goes wrong with launches, and I can't imagine it being a pleasant trip.

Nor would it be particularly cheap.  But sure, it is presumably possible.

[SomeGuy]

Quote:Composite materials suitable for the high temperatures of supersonic applications.

How would that make commercial supersonic flight cheaper?  It's already possible, has been for decades.

Quote:Um yeah there is.  You are showing a plot of drag coefficient CD.  Drag force is proportion to CD and speed squared. Since work is force integrated over distance, mpg would be correlated with drag force.  So even if CD returns to subsonic levels, fuel economy at 1500 mph would still be nine times less than at 500 mph.

What Mike said, and you still have to bust through the sound barrier both ways.  Aviation is a fairly mature industry, with a lot of money behind it already, and it still stagnated after the 70s.  I just don't think we are going to see these sorts of radical improvements you're hypothesizing in the absence of some sort of technical advancement a damned site more impressive than cool composites.

[Mikebert]

(01-10-2017, 01:28 PM)SomeGuy Wrote: You mention comparative advantage, you might want to look up what David Ricardo actually said concerning situations where one trading partner has a consistent advantage in all or most goods, what he thought that might do to the other country, and the ridiculous thing that he thought would prevent it.

Here.

[SomeGuy]

(01-16-2017, 03:20 PM)Mikebert Wrote:

(01-10-2017, 01:28 PM)SomeGuy Wrote: You mention comparative advantage, you might want to look up what David Ricardo actually said concerning situations where one trading partner has a consistent advantage in all or most goods, what he thought that might do to the other country, and the ridiculous thing that he thought would prevent it.

Here.

Thanks.  That's largely where I was going with that, that the "feelings" (which might have been a logical assumption at the time for all the reasons stated) that would prevent the mobility of capital are long since defunct, and in another section (concerning automation, funnily enough.  Oh how things change) that lower prices do not necessarily benefit workers if the decline in their income exceeds the price difference between old and new goods.

I suppose it's only really ridiculous if you consider that people still cite him now without actually, reading what he wrote and how the situation might be different today.

[SomeGuy]

Also,if we have quite finished irritating each other in the "regeneracy" thread, I'd like to continue the M & T discussion.  In my case I'd like to post the actual graphs and cycle dates, and definition of terms, from LSWP, and you in turn post what you think is wrong with it, how it should be extended, etc.  But I don't want to do that work if you're not going to participate.


Game?

[Warren Dew]

(01-16-2017, 03:13 PM)Mikebert Wrote:

(01-16-2017, 03:03 PM)Warren Dew Wrote:

(01-16-2017, 01:13 PM)SomeGuy Wrote:

Quote:Branson has been trying to provide supersonic service for some time; he tried to buy the remaining Concordes from British Air when British Air stopped flying them when the internet bubble burst.  That's why I view this as credible.  This company is connected to his Space Ship One venture, which is less likely actually to offer paid service, but which has relevant technology.

Don't get me wrong, I think all that stuff is cool, but I wonder what technology you'd think Space Ship One has that would translate into affordable supersonic commercial jets?

Composite materials suitable for the high temperatures of supersonic applications.

Actually this is interesting for another reason:  aerospace composites are a new technology, and Boeing already has a worldwide lead in them.  Since engineering is being done by a US team for this, it extends the US technology lead.  This is the kind of manufacturing I think the US can usefully emphasize:  emerging technologies where the US has a technical lead thanks to our strong University network.

Quote:

Quote:Supersonic flight is not inherently less fuel efficient on a per mile basis, just on a per hour basis.

Yes, it is.  Fuel use is largely a function drag, and drag is a function of speed.  In addition, the drag coefficient increases significantly after about Mach 0.8, pushing up fuel consumption dramatically.

It's not that it is impossible to fly past the sound barrier, I just question whether it is possible to do so cheaply.

But what would I know?

It's not that simple.  Drag coefficient increases substantially right at the sound barrier.  However, it then falls again at higher speeds.



If you're cruising at mach 2 or above, there's no fundamental reason why fuel economy has to be worse for supersonic flight.  There are differences due to much more research and development money being spent on optimizing engines for subsonic fuel efficiency, but that just means we ought to expect rapid improvement once fuel efficiency becomes a focus for supersonic engines.

Um yeah there is.  You are showing a plot of drag coefficient CD.  Drag force is proportion to CD and speed squared. Since work is force integrated over distance, fuel economy (i.e. work per distance) would be correlated with drag force.  So even if CD returns to its subsonic values, fuel economy at 1500 mph would still be nine times less than at 500 mph.

This is only true at constant altitude at subsonic speeds.

At supersonic speeds, the boundary layer speeds must remain subsonic due to speed of sound limitations, which changes how skin friction drag operates.

In addition, for both subsonic and supersonic speeds, higher speeds result in higher lift.  This permits aircraft to achieve adequate lift at higher altitudes where the air is thinner.  This in turn reduces drag.

Finally, at supersonic speeds, there is compressibility drag, but again, the compression wave can be used for lift.  This permits supersonic transports to cruise at much higher altitudes than subsonic transports, which again reduces drag relative to flying "in the soup".

[Warren Dew]

(01-16-2017, 03:19 PM)SomeGuy Wrote:

Quote:Composite materials suitable for the high temperatures of supersonic applications.

How would that make commercial supersonic flight cheaper?  It's already possible, has been for decades.

Reduced structural weight, resulting in larger payloads or reduced fuel consumption for the same payload.  There's a reason why airlines are replacing aluminum aircraft with the composite 787.  Also, reduced need for exotic metals like titanium to withstand temperatures in key locations.

[SomeGuy]

Quote:This is only true at constant altitude at subsonic speeds.

At supersonic speeds, the boundary layer speeds must remain subsonic due to speed of sound limitations, which changes how skin friction drag operates.

In addition, for both subsonic and supersonic speeds, higher speeds result in higher lift.  This permits aircraft to achieve adequate lift at higher altitudes where the air is thinner.  This in turn reduces drag.

Finally, at supersonic speeds, there is compressibility drag, but again, the compression wave can be used for lift.  This permits supersonic transports to cruise at much higher altitudes than subsonic transports, which again reduces drag relative to flying "in the soup".

You say all of that, and yet I don't think that this actually cancels out the inherent drag from moving through even a thin atmosphere at LUDICROUS speed.  There's a reason that all of the actual supersonic aircraft built optimize their airframes to minimize drag, and take advantage of vortex lift at slow speeds when taking off and landing.

I'm still not seeing the fundamental breakthrough that allows this to be done in a cost-efficient manner.

[SomeGuy]

(01-16-2017, 03:49 PM)Warren Dew Wrote:

(01-16-2017, 03:19 PM)SomeGuy Wrote:

Quote:Composite materials suitable for the high temperatures of supersonic applications.

How would that make commercial supersonic flight cheaper?  It's already possible, has been for decades.

Reduced structural weight, resulting in larger payloads or reduced fuel consumption for the same payload.  There's a reason why airlines are replacing aluminum aircraft with the composite 787.  Also, reduced need for exotic metals like titanium to withstand temperatures in key locations.

Yes, but are they cheap?

[Warren Dew]

(01-16-2017, 03:54 PM)SomeGuy Wrote:

Quote:This is only true at constant altitude at subsonic speeds.

At supersonic speeds, the boundary layer speeds must remain subsonic due to speed of sound limitations, which changes how skin friction drag operates.

In addition, for both subsonic and supersonic speeds, higher speeds result in higher lift.  This permits aircraft to achieve adequate lift at higher altitudes where the air is thinner.  This in turn reduces drag.

Finally, at supersonic speeds, there is compressibility drag, but again, the compression wave can be used for lift.  This permits supersonic transports to cruise at much higher altitudes than subsonic transports, which again reduces drag relative to flying "in the soup".

You say all of that, and yet I don't think that this actually cancels out the inherent drag from moving through even a thin atmosphere at LUDICROUS speed.  There's a reason that all of the actual supersonic aircraft built optimize their airframes to minimize drag, and take advantage of vortex lift at slow speeds when taking off and landing.

I'm still not seeing the fundamental breakthrough that allows this to be done in a cost-efficient manner.

The Concorde had about the same fuel burn per passenger mile as the first generation 707.  There hasn't been any fundamental breakthrough in subsonic jets since then, despite a manyfold improvement in fuel economy; there was just incremental improvement, mostly from higher and higher bypass ratios, resulting in a high degree of optimization for subsonic jets.

I'd expect the same gradual improvement for supersonic jets once they become common.

[Eric the Green]

"Report Card for Donald Trump" That title always makes me chuckle. Considering his appointments, there's only one grade possible for his report card:

FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF----------------------------------------------------

Now, if he wants to do better, he's going to have to rev up his slogan from his TV show and use it a lot!

I expect continual twitter wars and outrages, until people get used to the idea that Trump is more interested in his ego than his new job.

[SomeGuy]

Quote:I'd expect the same gradual improvement for supersonic jets once they become common.

Emphasis mine.  I still don't see why they should BECOME common in the first place.  It would be interesting, but that's not the same thing.

[Mikebert]

Looks like Trump has drawn his first red line.  Didn't take him long.

http://www.theamericanconservative.com/l...ith-china/

Trump seems to be a big hurry, he's already working on objective six. I also notice the administration is making more noise on trade than on immigration. My belief has been that his trade policies are something *he* wants, whereas his immigration policy is more of something his voters want.
Not sure where he is going with this.  Maybe its no where.

[SomeGuy]

(01-24-2017, 05:57 AM)Mikebert Wrote: Looks like Trump has drawn his first red line.  Didn't take him long.

http://www.theamericanconservative.com/l...ith-china/

Trump seems to be a big hurry, he's already working on objective six. I also notice the administration is making more noise on trade than on immigration. My belief has been that his trade policies are something *he* wants, whereas his immigration policy is more of something his voters want.
Not sure where he is going with this.  Maybe its no where.

I think the thing with China was largely baked into the cards.  Have been saying so for years.  Better China than China AND Russia, I suppose. 

We'll see if they double down on this, or just use it as a negotiating bit.  Let's give him the proverbial 100 days, and see how this plays out.  Not just with China, but trade/immigration, too.

[Mikebert]

(01-24-2017, 08:34 AM)SomeGuy Wrote: I think the thing with China was largely baked into the cards.  Have been saying so for years.  Better China than China AND Russia, I suppose. 

We'll see if they double down on this, or just use it as a negotiating bit.  Let's give him the proverbial 100 days, and see how this plays out.  Not just with China, but trade/immigration, too.

I agree on the first.

I don't think anything will come of the China thing.  Trump would have to push the issue.

I am very interested in the trade thing.  It is possible Trump may loose interest and drop the ball on the stuff he ran on which is opposed by movement conservatives, but I hope not.

[SomeGuy]

(01-24-2017, 02:13 PM)Mikebert Wrote:

(01-24-2017, 08:34 AM)SomeGuy Wrote: I think the thing with China was largely baked into the cards.  Have been saying so for years.  Better China than China AND Russia, I suppose. 

We'll see if they double down on this, or just use it as a negotiating bit.  Let's give him the proverbial 100 days, and see how this plays out.  Not just with China, but trade/immigration, too.

I agree on the first.

I don't think anything will come of the China thing.  Trump would have to push the issue.

I am very interested in the trade thing.  It is possible Trump may loose interest and drop the ball on the stuff he ran on which is opposed by movement conservatives, but I hope not.

Some of those areas are fairly sensitive, Trump might not have to push very hard.

Yeah, I am really curious (and concerned) to see how Trump's relationship with the movement conservatives in Congress plays out, and how that affects what (if any) policies come out.  It's a tough balancing act for both of them.