A little-appreciated fact is that the rocket must generate aerodynamic lift

I believe that Elon Musk mentioned the angle of attack required of the rocket body cylinder during the press conference after the most recent launch.

B. There is nothing inherently improper with wings or fins located forward on the body of a missile, as they are on virtually every air-to-air missile in existence. The fact that they are located on the aft end of the MOAB is a design choice appropriate to their application in a minimalistic guidance system of a gravity bomb.

Prior to obtaining orbital velocity, an orbit-bound rocket must maintain a slight "nose high" attitude to develop a thrust vector upward, preventing it from descending below the desired trajectory, unless it has wings!

...Launch vehicles spend most of the time out of the atmosphere.Quote from: drunyan8315 on 04/16/2017 05:25 AMPrior to obtaining orbital velocity, an orbit-bound rocket must maintain a slight "nose high" attitude to develop a thrust vector upward, preventing it from descending below the desired trajectory, unless it has wings!Wrong. Launch vehicles don't flight with "canted" thrust vector to counter gravity. The rocket is in free flight, there is no side gravity force. An astronaut only feels the thrust of the engine and not a pull to the center of the earth and not to a floor like an airplane. If an airplane had strong enough engines, it wouldn't need wings.

Forgive me if this is covered elsewhere, couldn't find anything.I've just noticed that the SpaceX coverage of NROL-76 uses m/s (metres per second), but CRS-13 uses km/h (unit of the antichrist).The former is a proper SI unit of speed (yes I know some of you want feet per second or furlongs per fortnight, but SpaceX went metric, don't blame me).My problem is km/h. Really? The only time I have ever seen that is the speedometer in a car.Ok, so I'm British and less than 60 so I use m/s for engineering. When I'm driving, it's miles/hr.I would be willing to bet SpaceX use SI units (kg/seconds/metres) internally. So why on earth would they switch the coverage to use km/h?

The technical webcast (when it's broadcast, which is not every flight) only shows m/s.

For some reason I have trouble converting that [km/h] in my head to m/s,

My problem is km/h. Really? The only time I have ever seen that is the speedometer in a car.I would be willing to bet SpaceX use SI units (kg/seconds/metres) internally. So why on earth would they switch the coverage to use km/h?

Quote from: nicp on 12/21/2017 08:05 PMMy problem is km/h. Really? The only time I have ever seen that is the speedometer in a car.I would be willing to bet SpaceX use SI units (kg/seconds/metres) internally. So why on earth would they switch the coverage to use km/h?I would like they use km/s (or m/s, conversion is trivial). Something like 18000 km/h is absurd number. I never encountered such long distances in my life and have no slightest idea how fast 18000 km/h is. In contrast, 5000 m/s (or 5 km/s) is the distance from my home to Auchan, covered in just one second. Wow, it's pretty fast!

Quote from: nicp on 12/21/2017 08:17 PMFor some reason I have trouble converting that [km/h] in my head to m/s, Divide by 4, then add 10% of your new total. quick conversion. It's obviously not perfectly accurate. But the actual conversion is to multiply by (1000/3600)=0.277| (sorry that's supposed to be 7s repeating, not sure how to type a bar) and my way is the same as multiplying by 0.275. If you need additional accuracy, you can keep taking and adding 10% of your previous 10%. So, say the speed is 8000 km/h. That gives 2000 +200 +20 +2 +..... and just keep adding 10% of the previous adjustment until you reach enough accuracy.

Quote from: deruch on 12/22/2017 09:35 AMQuote from: nicp on 12/21/2017 08:17 PMFor some reason I have trouble converting that [km/h] in my head to m/s, Divide by 4, then add 10% of your new total. quick conversion. It's obviously not perfectly accurate. But the actual conversion is to multiply by (1000/3600)=0.277| (sorry that's supposed to be 7s repeating, not sure how to type a bar) and my way is the same as multiplying by 0.275. If you need additional accuracy, you can keep taking and adding 10% of your previous 10%. So, say the speed is 8000 km/h. That gives 2000 +200 +20 +2 +..... and just keep adding 10% of the previous adjustment until you reach enough accuracy.Actually, there's an easier way - the conversion factor is 3.6. There are 3600 seconds in an hour; a kilometer is 1000 meters. Therefore, an object travelling 1m/s travels 3.6km in an hour. So, 18000km/h = 5000m/s, because 18000 / 3.6 is 5000, while 7000m/s = (7000 * 3.6)km/h = 25,200km/h.Easy conversions like that are one of the advantages of the metric system.