### Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

### Messages - DuncanDoenitz

Pages: [1] 2 3 ... 8  Next >
1
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 27, 2021, 01:38:16 PM »
This is the difference between arithmetic and science.  You are putting data into a calculator and expecting it to work it out for you.  You can't do that if you haven't got your head around the science first.  If we actually wanted to know the terminal velocity of the skydiver, or how long it takes him to impact, the calculator would be great.  But we don't.  If we had 2 identical spheres of pure gold, and wanted to know the weight one of them we could weigh it using some kind of scales to balance against a known mass.  Or we could determine the volume of water it displaces, and multiply by the density of pure gold.  But we don't, we only want to know if they are identical, so we can just balance them together on scales.  No calculations.  No numbers.

Lets see where we disagree on the science:

Round Earth

The skydiver has mass, and he will be accelerated downward by a force of 9.81 m/s/s multiplied by his mass.
At the instant of release, he will feel weightlessness, as the force of gravity is not being opposed.
As soon as he develops airspeed he will feel an opposing force upward due to aerodynamic drag.
The drag force is proportional to his size and shape, and to the square of his airspeed.
As soon as he develops airspeed, and hence drag, he will begin to feel some of the effect of gravity.
Because he is feeling a downward force (Gravity) opposed by an upward force (drag), his airspeed will increase at <9.81m/s/s.
As airspeed increases, the force of drag will increase.
At a particular airspeed, the increasing force due to drag will equal his mass multiplied by 9.81 due to gravity.  He will stop accelerating.  His airspeed will be constant thereafter, until impact.  This is the Terminal Velocity (TV).
He is no longer weightless, as he is being supported by the force of drag so feels the effect of gravity.
The force of drag is not a constant; it increases with airspeed until stabilizing at terminal velocity.

If he was a styrofoam mannequin, but with the same aerodynamic size and shape, the upward drag-force would equal his gravitational down-force at a reduced airspeed, so his TV would be lower, so time-to-impact would be longer.

Flat Earth

Prior to jumping, the skydiver is at identical altitude to the RE case.
The human skydiver has identical mass and aerodynamics.
Prior to jumping, skydiver has the same upward velocity and (UA) acceleration as Earth.  His airspeed is zero.  (His speed relative to the universe is the same as Earth, a gazillion mph, but we are only interested in speed relative to the Earth/Atmoplane).

He jumps....

For a few milliseconds his airspeed remains zero, but he is no longer accelerating upward and his universal speed is constant.  He experiences weightlessness.
At no point is he subjected to acceleration downward.
The Earth continues to accelerate upwards at 9.81 m/s/s.  As the Atmoplane is static with respect to Earth, it also accelerates at 9.81m/s/s, unmitigated by any aerodynamic forces.
As the skydiver has constant Universal Velocity, but the atmoplane is accelerating upward, then he will begin to experience an upward airspeed.
As the airspeed increases at 9.81m/s/s, the skydiver will become subject to the force of drag, which will increase identically to the RE case, as his aerodynamic properties are identical.
As soon as he develops airspeed, and hence drag, he will begin to feel some of the effects of UA; no longer weightless.
This upward force will be opposed by the inertia of the skydiver due to his mass, which is identical to the RE case.
As he continues to accelerate upwards with respect to the universe, the rate of acceleration will increase, due to increasing airspeed, until the upward force of drag equals his mass multiplied by 9.81 (due to UA).  This is TV.
At TV, his acceleration is now identical to the Earth/Atmoplane, but his Universal Velocity is lower, so  the Earth will be  catching up.
He is no longer weightless, as he is being accelerated at 9.81m/s/s by the atmosphere.

If he was a styrofoam mannequin , the upward drag force would equal his mass multiplied by UA at a lower airspeed, so he would have a lower TV.  Because his TV is lower, his UV is higher, hence closer to that of Earth.  Because he is now accelerating at the same rate as Earth, but spent less time un-accelerated, earth will still impact him, but time to impact would be longer.

In summary; same mass, same drag, same acceleration.  Different pos/neg signs.

Please let us know if you (or anyone) have a problem any these statements.

2
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 26, 2021, 09:52:08 PM »
You found an online calculator for a Flat Earth Skydiver??

3
##### Flat Earth Investigations / Re: Branson to go only 55 miles up !
« on: July 26, 2021, 07:04:02 PM »
Personally, I'm not convinced of any shape to be determined from what are obviously short focal-length cameras on the Virgin craft.  Face it, the cameras are not there for science, they are there to provide shiny publicity images for the Virgin operation.  You are always going to get this when the camera is attached to the device it is photographing.  The image from Felix Baumgartner's capsule is another example.

Having said that, the FE cause is hardly advanced by Pete giving us 3 screenshots from at least 2 different cameras, taken at airliner-altitude and purporting to show concavity (unless, of course, he is just seeking to demonstrate the futility of our attempting to draw such conclusions).

On the other hand, the RE cause is not advanced by making unsubstantiated claims about what we think the craft passengers saw through the enormous windows.

4
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 25, 2021, 11:57:08 AM »
First of all, your (light brown) "47 second" line is not valid because it is a straight line.  It should be a curve as the object is accelerating, until it reaches terminal velocity, at which point it will become straight.  What is the terminal velocity?; depends on the aerodynamic drag.  You can't just interpolate linear points between zero and 47 seconds.

Second of all, you seem to be adding the acceleration of the (RE) skydiver to the acceleration of (FE) Earthing in coming to your 8 second and 11 second estimates.

Third of all, you are still including a hypothetical starting velocity of 100-somethings.  The initial velocity is zero, because that is the relative velocity of Earth and the object/skydiver.

Look at it again:

Initial relative velocity of object to Round Earth-and-atmosphere = zero.  Initial relative velocity of object to Flat-Earth-and-atmoplane = zero.

RE acceleration due to gravity = 9.81.  FE acceleration due to magical UA = 9.81.

Drag-coefficient of object is identical in both scenarios.

On release, object and Earth initially accelerate towards each other at identical rates in both scenarios.

Airspeed of the objects develops identically in both scenarios.

As airspeed is identical, the force of drag is identical.

RE object will continue to accelerate due to gravity at 9.81, opposed by drag (which is increasing with airspeed) until the force of drag = force of gravity.  At this point, Terminal Velocity, the object will stop accelerating and will continue to fall at constant velocity until impact.

Flat Earth-and-atmoplane will continue to accelerate at 9.81.  The object is not accelerating due to UA, but begins to feel an upward force due to drag as the atmoplane develops airspeed around it.  The drag increases with airspeed until its force = 9.81.  At this point, Terminal Velocity, the object will have identical acceleration to the Earth-Atmoplane.  Although its acceleration is identical, its universal velocity is lower, so the FE continues to approach it until impact.

It doesn't matter what the numbers are.  For the same object in the same density air; the relative starting-velocity is zero, the acceleration of the object/air due to gravity/UA is identical, therefore the airspeed is identical, therefore the drag is identical, therefore terminal velocity is identical, therefore time-to-impact is identical.

5
##### Flat Earth Investigations / Re: Branson to go only 55 miles up !
« on: July 24, 2021, 09:23:28 AM »
The FAA know as we all do that this is a very 'cheap' claim from these billionaires who have trawled for the lowest bar possible and want to hand out the accolade of astronaut to anyone who pays up.

Now that's not really what NASA et al want. They want you to think astronauts are brave. And so when men were in rocket aircraft in the 1960s breaking speed and altitude records, they wanted to give them something for that. Little astronaut wings. But just sitting on a small private aircraft to receive the same honour cheapens it.

So they've got them on "You just sat there and did nothing". I'm sure they'd like to get them on "You're not in space" but then they have to remove the honours they handed out to men who actually deserved them.

But the thing about truth is that the FAAs or NASAs version of it is neither here nor there. At 85km ... Branson is still in the territory of clouds. I don't care what NASA say, you don't get clouds in space.

Will be interesting to see if the pilots of Branson's aircraft get given astronaut wings because they weren't sat there doing nothing. That would put Branson's nose right out of joint.
For the record, no, they didn't "get given" astronaut wings following this flight.

In fact, they didn't "get given" anything following this flight.  Dave Mackay and Michael Masucci both already earned their FAA accredited astronaut wings as test pilots of VSS Unity in 2019.

And 100%, in my opinion, Sir Richard and the other passengers have been to space, but have not earned anything.

6
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 23, 2021, 09:03:35 AM »

Don't sweat it, its an interesting thought experiment, but I don't know what the drag coefficient of our hypothetical object is either.  The thing is, its like a wind tunnel.  Happy with that concept?  Drag increases with velocity, doesn't matter whether our object is accelerating in still (RE) air, or it's stationary in accelerating Wind Tunnel/FE air; same result.  And the relative acceleration is always going to 9.81 m/s/s.

7
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 23, 2021, 08:42:47 AM »
Quote
You are the one who introduced it to begin with, that's why I am asking you.

Sorry I wasn't more clear.  I meant I don't have the answers to that question because it's not my theory.  The earth has been accelerating according to FE, so at any given moment it has an "initial velocity".  I just picked 1000 at random.  And I don't know what it is supposed to be relative to because the story keeps changing.  Is the relative velocity between the earth and a falling object 0?  If so, and they are accelerating at the same rate, then they would never meet.  So the velocity of the falling object must be different, but I don't know what that is supposed to be, so i just started with 9.8 at 1 second.  If you think it should be something else, I can change it.

The velocity and acceleration of a SUSPENDED object are IDENTICAL to EARTH.

At the INSTANT of RELEASE, the velocity is identical, BUT THE OBJECT STOPS ACCELERATING.

In the seconds following release, the OBJECT MAINTAINS CONSTANT VELOCITY, BUT THE EARTH CONTINUES TO ACCELERATE, so it starts to catch up with the object.

8
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 22, 2021, 12:16:11 AM »

1.  First, nice that you've shown some calculations.  Thank you.

2.  You seem to be using a mixture of SI, MPH and Ft/Sec which is confusing.

3.   How did you calculate the aerodynamic drag?  I don't see a Cd.  What is its size and shape?  How have you incorporated Velocity-squared? Why is it in units of "Kg/m"?

4.  Why are you doubling the acceleration in the FE case?

5.   Why have you specified a Mass?  Its immaterial.  But you haven't specified a size and shape (Surface area and Cd)

6.  How have you  calculated that "with air resistance it will take 14 seconds ......".

7.  In FE (and why the f@@@ I am defending FE I'm not sure), the atmosphere is not providing any resistance to the Earth's acceleration, because there is no relative airspeed between the Earth and the atmosphere.  The Earth and its atmosphere are essentially one unit that is being accelerated upwards by a magical force*.  The acceleration of Earth serves to compress the atmosphere at its base, which is why its density decreases with altitude, but it is static, it has no inherent movement relative to the Earth so, so its velocity-squared equals zero, so its drag equals zero.

8.  I'm with Clyde; why 1000 mph (or m/s on the spreadsheet)?

* As a side issue, we may like to ask ourselves why, in the Earthly realm, Magical Acceleration only acts directly on the Earth.  Everything else is not accelerated, unless it is supported by the Earth directly (like houses, the atmosphere, you and me) or indirectly (like an aircraft supported by the atmosphere, or the 50 kg object in your hand).  Odd thing is, that all this stuff (the houses, the object, the aircraft, molten lava) is all actually made out of Earth, but doesn't float.  Weird.

9
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 21, 2021, 08:17:27 AM »
Quote
The Earth's initial velocity with respect to the about-to-be-free-falling object is 0mph. It seems like you aren't taking that into consideration. I don't know why you are choosing an initial velocity of 1000mph, what that velocity is supposed to be relative to, or how you are constructing this in your head, but I think you are adding some extraneous data points that are confusing you.

If the relative velocity between the object and the earth is 0 and rate of acceleration is the same, the earth and the object will never meet.  The distance between them will always be the same.

Duncan suggested that the object would be subject to some air resistance, which would change the relative velocities.  That’s reasonable. That would mean even though the initial velocities are the same, the rate of acceleration and the velocity of the object would be reduced and eventually the earth and the object would meet.

The problem is they would never meet in the same time frame that we see in reality.

With gravity at 9.8 and air resistance of 2.4 a 50 kg. object will fall 1000 ft. and meet the ground in 10 seconds. That makes the effective rate of acceleration 9.5  That’s what we would expect to see in reality, using standard method of calculation.

So if we have the earth accelerating up from 0 height at 1000 mph and 9.8 and the object accelerating up from an initial height of 1000 ft. at a rate of 9.5, at the end of 10 seconds the object would be at 17225 and the earth would be at 16274.  They are still 951 feet apart.

(In the FE Model); Immediately upon release, the Earth&Atmosphere&Object have identical velocities.  However, while the Earth&Atmosphere continue accelerating up at 9.81 m/s/s, there is now no force whatever acting upon the object so it is at constant velocity, so the Earth&Atmosphere will start to catch up with the Object.

In the seconds following release, as the accelerating atmosphere begins to have velocity relative to the object, the Object will become subject to aerodynamic drag, which will provide a force Up, beginning to accelerate the Object upwards.

It is important to note that this is upward force is not a fixed quantity. (I don't know how you came up with a figure of 2.4 (units?) for a 50 kg object).  The upward force is directly proportional to the Object's size and shape (technically, its surface area and Drag Coefficient), to air density (so it is reduced at higher altitudes) and to the square-of-air-velocity.  That "square" is important, as it means the drag force is very small at low velocities, but increases rapidly with higher airspeed.  It is not a constant force, it increases as velocity increases.

Please note that the upwards force is completely unrelated to mass.  Flat or Round Earth;

1.   The "downward" force ("gravity" or "UA") is related only to mass and a constant rate of acceleration.
2.   The "upward" force is completely unrelated to mass.  It is related only to size and shape of the Object, air density, and the square of relative-velocity.

All of this is exactly like RE, applying Jack's pos/neg sign changes.

10
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 20, 2021, 02:21:00 PM »
Quote
But if you drop an object with initial velocity zero, then that initial velocity is with respect to the earth's surface, so both the object and the earth (and indeed the atmosphere) are moving at the same velocity. From the moment it leaves your hands, the earth and atmosphere would continue accelerating, but the object would not, other than a small acceleration caused by the atmosphere pushing on it.

If the object and atmosphere are accelerating up at the same rate and velocity as the earth, the earth and the object would never meet.
When released, the object is not accelerating up, but the Earth-and-atmosphere are.  Once the object begins to feel airspeed, it will begin to accelerate up again, but not at the same rate as Earth-Atmosphere.  The amount of acceleration it gets from aerodynamic drag is directly proportional to its size and shape, but it will always be less than the acceleration of Earth-Atmosphere.

11
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 20, 2021, 08:27:22 AM »
Just for the record, Jack appeared to agree with me.  That is not necessarily the same thing as me agreeing with Jack.

However; I was stating that a Round-Earth case, where a "falling" object accelerates downward towards a constant-velocity planet whilst being opposed by aerodynamic drag, produces the same effect as a hypothetical disc-world accelerating upward towards a constant-velocity object, with the atmospheric air-cushion providing an equivalent upward aerodynamic force.

Yes, acceleration is a vector quantity.  In RE it's (what we perceive as) "Down", and in FE it would be "Up".  So yes, I would still agree with Jack that this would represent a simple change of pos/neg, and the magnitude remains identical.

In both cases, and again I think Jack would agree, the aerodynamic accelerating force is always "Up".

He is also correct in bringing up the Archimedes effect, which is independent of aerodynamics.

It is not exactly the same - on a hypothetical upwards accelerating disc world, gravity would be uniform world-wide. Whether you are standing on top of Mt. Everest, or sailing on the Indian Ocean, you should experience the same downward acceleration no matter where you are on the plane. Such would be the nature of an upwards accelerating plane.

But the reality is that you do not experience the same gravity everywhere on earth. Because the Earth is not a perfect sphere, you can have a variable distance to the Earth's center, which has a tiny, but measurable effect on the gravity you experience. Gravity is 9.7803 metres per second squared at the equator and 9.8322 m/s2 at the poles. Mount Nevado Huascarán in Peru has the lowest gravitational acceleration, at 9.7639 m/s2, while the highest is at the surface of the Arctic Ocean, at 9.8337 m/s2.

Agreed.  I was answering the OP's question.

In practice, there are variations in Planet-Earth's surface g, just as there are variations in the atmospheric drag due to the vertical component of atmospheric currents (like thermals).

12
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 19, 2021, 10:30:49 PM »
Just for the record, Jack appeared to agree with me.  That is not necessarily the same thing as me agreeing with Jack.

However; I was stating that a Round-Earth case, where a "falling" object accelerates downward towards a constant-velocity planet whilst being opposed by aerodynamic drag, produces the same effect as a hypothetical disc-world accelerating upward towards a constant-velocity object, with the atmospheric air-cushion providing an equivalent upward aerodynamic force.

Yes, acceleration is a vector quantity.  In RE it's (what we perceive as) "Down", and in FE it would be "Up".  So yes, I would still agree with Jack that this would represent a simple change of pos/neg, and the magnitude remains identical.

In both cases, and again I think Jack would agree, the aerodynamic accelerating force is always "Up".

He is also correct in bringing up the Archimedes effect, which is independent of aerodynamics.

13
##### Science & Alternative Science / Re: FE and ICBMs
« on: July 16, 2021, 02:10:20 PM »

And you keep using "that word," when you call out what is, quite obviously, TWO WORDS.

Have a nice day.

Since we're not advancing the argument at this stage, I think you quite obviously mean "..... what are, quite obviously, TWO WORDS".

Anywho; Has everyone heard of "muzzle velocity".  Its the key parameter in the ballistics of firearms and artillery.  Nothing to do with rates of acceleration.   Nothing to do with average speed in the barrel.

Muzzle velocity.  The instantaneous speed at the end of burn.

14
##### Science & Alternative Science / Re: FE and ICBMs
« on: July 15, 2021, 01:02:48 PM »
A Formula 1 race starts when the red lights go out, not when the car starts moving.  If a car is moving when the red lights go out, it is disqualified.

Its velocity at the start is zero.

15
##### Flat Earth Investigations / Re: Branson to go only 55 miles up !
« on: July 14, 2021, 01:04:28 PM »
Where does London start?  City of London?  Greater London?

London is enormous. You missed another of its excellent airports. London Oxford Airport.

No, I didn't miss it.  I was listing the destinations offered by a particular service provider.  But you are correct in pointing out that other alternatives are offered by other providers.

Now, it calls itself Windsor castle, but I think it is pretty obvious that it is not Windsor castle.

With respect, its only obvious to you because you did your research.  You would want to be sure that its a "Windsor Castle" that satisfies your requirements before you book an Uber.  Would you want to finish up at the the big fortified house in Berkshire, for instance, when your mates are waiting for you down at the pub?  If I was going to spend several hundred thousand dollars on a ticket from Sir Richard, I think I would first satisfy myself with where he was taking me.  Its on the VG website:

APOGEE
Nearly 300,000 feet above Earth, the cabin becomes your playground to unbuckle and experience weightlessness.

16
##### Flat Earth Investigations / Re: Branson to go only 55 miles up !
« on: July 14, 2021, 10:26:22 AM »
Where does London start?  City of London?  Greater London?

Easyjet claims to be able to fly me to 4 airports in London; London Gatwick, London Luton, London Southend, and London Stansted.  None of these are within any recognised boundary of the City, and Stansted is actually 47 Km from the Tower of London.

So are they mis-selling?  I'm an intelligent kind of guy, and before I spend my £19.99 I'm going to do my research see if its where I want to go.  I could pay more and get a helicopter into Hyde Park.  Or maybe Luton is close enough to satisfy me.  (Disclaimer; have you been to Luton? Don't).  Can I buy a souvenir London Bus at Gatwick?  You betcha!

Branson's marketing is quite clear on what you're getting for your money.  You want more?  Just like Easyjet, the developing market is filling up with alternative providers, who will fly you to London City, Earth-orbit, or (potentially) the Moon.

17
##### Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: July 12, 2021, 10:10:13 AM »
By "light", I assume you mean "less dense".

Same as Round Earth.  In RE all matter with mass is attracted to the Earth at the same rate of acceleration, but as soon as it develops velocity it becomes subject to aerodynamic drag.  The drag of less dense items is generally greater than denser ones due to the difference in surface area, so they feel more drag, so they move more slowly.  eg; a one gram feather has more surface area than a one gram lead-pellet.

In FE, the atmosphere ("atmo-plane" in FE yuk-speak) is supported by the Earth so accelerates at the same rate.  Hold the lead-pellet and the feather in your hand and they are feeling Universal acceleration because your feet are on the accelerating Earth.  Release them, they stop accelerating, but the Earth and atmo-plane continue accelerating towards them.  The pellet has a smaller surface area, so experiences less drag and remains relatively stationary.  The feather, due to its larger surface area, feels more drag so starts accelerating upwards in the airstream so, to the observer, appears to fall less slowly.

If both items were in a vacuum chamber they would fall at the same rate, RE or FE.

18
##### Science & Alternative Science / Re: FE and ICBMs
« on: June 21, 2021, 03:05:40 PM »
Oh Jesus. 7.17km/s is a velocity. As he says in his quote. They have different units than acceleration. Slow down. Take a breath.
If you understand enough to correct what it should be to your own mind, then run with it.

This is you objectively fucking up and then doubling down on it. What will it take for you to understand that you aren’t currently knowledgeable enough to analyze this issue?
The rate I put forth is fine. I mistakenly put the word acceleration instead of the word velocity.

Kindly pat yourself on the back, take two if you care, my apology for using the wrong word in this case, and have a great rest of your day.

Before you go, if you can explain how a 16,038 mile per hour velocity at t+5 could possibly translate into an average rate of 3,000 mph over 5 minutes, that would be terrific.

ETA: To totally satisfy what appears to be a certain need for perfection in others, 0 - 16,038 mph translates to an acceleration of 23.9 m/s2.

You need to understand the difference between an average and an absolute.  The average family has 2.4 children. So does an average family exist?

In physics, averages might make for interesting comparison, but are no basis for calculation.  The only considerations in calculating the energy state at a particular instant are its instantaneous position and velocity.

Consider this; Urbanville and Townsville and are 60 miles apart.  They are served by a train which does the journey in one hour.  How the f*** are you supposed to get off the train in Townsville if it is doing an average of 60 mph?

19
##### Science & Alternative Science / Re: FE and ICBMs
« on: June 21, 2021, 11:08:10 AM »
You are completely missing the point.  Kinetic energy and momentum have nothing to do with average speed, and even less to do with "average acceleration".  The only relevant number is its instantaneous velocity at the time of engine shutdown.  Do you not understand anything about physics?  If the average acceleration equals 3000 kmph (what?), do you not understand that the RATE of acceleration has been increasing exponentially for the entire 5 minute burn due to the decreasing mass of the projectile?

Sorry to appeal for assistance, but can anyone out there help him with this?

20
##### Science & Alternative Science / Re: FE and ICBMs
« on: June 19, 2021, 06:04:22 PM »
I think the "missile" aspect is also a little challenging.

He claims some experience of witnessing a Tomahawk;  "I cannot get into any particulars, except to state it was testing".

A cruise missile, of course is fundamentally different to most other guided missiles.  A solid-fuel booster accelerates it to cruise speed, where a turbine engine takes over and propels it at a fairly constant sub-sonic speed for the next several hours under aerodynamic control to its target.  And the cruise engine keeps running right up to impact.  This was the design of the WW2 German V1, and every cruise missile since.

I'm guessing he may also have difficulty with the concept of, for instance AAMs like AIM-9 Sidewinder, AIM-7 Sparrow and early AIM-32 ASRAAM, where the solid-fuel rocket motor accelerates it rapidly to multi-mach numbers within 2 or 3 seconds, and it glides the rest of the way to its target.  Judging from his posts, he seems to think that a (obviously fictional) ICBM motor should run until, at least, apogee.

Pages: [1] 2 3 ... 8  Next >