Gravity, Air Friction, Drag, 50, 60, 70, 100 miles up?

[gary350]

German V2 rocket engine burn was 70 seconds. Rocket speed about 4000 ft per second. Rocket launched straight up for 3 seconds then turned to a 42 degree angle. There is a lot of counterdicting information online about how high up V2 want and how far it flew but that is not the point. Engine burn out was about 60 miles down range and about 50 miles up but rocket continues to go up for about 100 miles or so before it leveled off and started down. Germans could make adjustments to shoot V2 to 4 different towns. V2 went 120 to 230 miles before coming down. After engine burn out the rocket coasted for 60 to 170 miles,drag & gravity must be very low. After the war ended it was learned Germany was able to shoot the V2 to New York city but was waiting until after winning the War and took over all of Asia. The V2 was very primitive technology compared to today's technology the rocket had to coast 2000 of miles to reach USA.

How much less air friction = drag is there in space. It must slowly get less and less the higher you go?

How much less gravity is in outer space. It has to get less and less too the higher up you go?

Rockets never burned up on re entry they never went faster than 4000 mph.

It is very interesting to me German engineers could calculate where the rocket would land, how was it possible to know things like gravity & drag 80 miles up no one had ever been there?

 

[A.T.]

After the war ended it was learned Germany was able to shoot the V2 to New York city ...

But not from Europe. They had plans to tow underwater launch silos by submarines closer to the US shore (see time 5:30 in the video).

 

[Delta2]

About how gravity changes as we go higher and higher the intensity of gravitational field at height h above the surface of the Earth is given by the formula $$g(h)=G\frac{M}{(R+h)^2}$$ where $M$ the mass of Earth and $R$ the radius of Earth and $G$ the universal gravitational constant.

This formula which I believe is known since Isaac's Newton's era is valid if we consider the shape of the Earth to be perfect sphere and if we consider as negligible the gravitational influence of other celestial bodies (e.g Moon).

 

[Delta2]

Generally speaking, the science is usually ahead of technology. Even modern computers can be almost totally explained by classical physics(classical electromagnetism and classical and statistical mechanics) which were known from the 1880s. Now days we have relativity that tell us what happens at speeds near the speed of light but unfortunately the technology is a bit behind, fastest ever space probe made by human traveled at a speed like 1% of speed of light.

German engineers, pushed in many ways by the Nazi regime, just found new inventions and new applications for science (in short new technologies, cause that is what technology is about, the application of science to solve practical problems), a science that was already known many years or centuries ago.

 

[A.T.]

... how was it possible to know things like gravity & drag 80 miles up no one had ever been there?

As Delta noted, Newtonian Gravity was known for centuries and the density of the atmosphere was also mostly predictable by laws known at the time. But they also had the rockets themselves to do these measurements and experiments. They didn't hit London with the very first V2 that flew. They also fired some vertically up to collect data.

 

[Lnewqban]

...
How much less air friction = drag is there in space. It must slowly get less and less the higher you go?

How much less gravity is in outer space. It has to get less and less too the higher up you go?
...

The following link shows that the density of air dramatically decreases during the trajectory, but gravity not so much:

https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html

The drag force is directly proportional to the density ($\rho$) of the surrounding air.

Fd = cd 1/2 ρ v2 A

Fd = drag force
cd = drag coefficient
ρ = density of fluid
v = flow velocity
A = characteristic frontal area of the body

 

[hutchphd]

But not from Europe. They had plans to tow underwater launch silos by submarines closer to the US shore (see time 5:30 in the video).

And on the drawing board was the A9/A10 which in some configurations used the A4 (V2) as a second stage to hit the US. This was a not a ballistic missile per se but an hypersonic aircraft.