So, who wants to win 1 million Euro?

[Echnaton]

So what does everyone think? Is it time for me to ban Heiwa if he doesn't start showing some willingness to learn? Or are you happy to keep using Heiwa's ignorance for your own self education?

Perhaps we could enforce the requirement that he limit the discussion to answering direct questions. It will at least give him one last chance to make a point. 

[dwight]

I didn't want to do this.

Heiwa

The European Maritime Safety Agency (EMSA) is a European Union agency charged with reducing the risk of maritime accidents, marine pollution from ships and the loss of human lives at sea by helping to enforce the pertinent EU legislation.

I wrote to EMSA a few days ago.  Not only did they say Heiwa Co was not in any way connected with them, or European maritime safety, but they had never even heard of Heiwa Co.

You are acting fraudulently, yet you froth and foam with rage while launching accusation at others.  Do you see why we are having problems?

Yeah, Heiwa, where is the pleasure you seem to derive from pointing out other people's error, now that the tables have turned? Or is that an element of you that the some would say is "best left unsolved"?

[Heiwa]

It has been repeatedly demonstrated how Apollo went to the Moon and back.

Yes, it has in several reports that I use as reference - see link in post #1. I evidently do not believe these reports and therefore we have this friendly discussion. Let's keep it that way.

See, e.g. my post #786. Can you really show by engineering calculations that you can slow down a 43.5 ton space ship from 2 400 to 1 500 m/s speed in space by burning 10.8 ton fuel at 30 kg/s producing a 97 400 N force?

Or that a 5.6 ton module of thin plates/stiffeners arriving into Earth's atmosphere at 11 200 m/s speed is slowed down by friction turbulence to 100 m/s speed during 18 minutes without heating up the inside at all? A few centimeters away the air is glowing hot, the heat shield is at 1600°C and inside - 20°C!

[Chew]

I want to see Heiwa's equation for aerodynamic drag that somehow allows a parachute to slow an object, doesn't allow a re-entering spacecraft to slow down, but does allow a meteroid to burn up in the atmosphere. I'm sure every automobile manufacturer would pay a billion dollars for an equation that actually worked in the real world that would enable them to create a drag-free 1000 mile per gallon car.

[Zakalwe]

I didn't want to do this.

Heiwa

The European Maritime Safety Agency (EMSA) is a European Union agency charged with reducing the risk of maritime accidents, marine pollution from ships and the loss of human lives at sea by helping to enforce the pertinent EU legislation.

I wrote to EMSA a few days ago.  Not only did they say Heiwa Co was not in any way connected with them, or European maritime safety, but they had never even heard of Heiwa Co.

You are acting fraudulently, yet you froth and foam with rage while launching accusation at others.  Do you see why we are having problems?

I'm finding it difficult to believe that someone who has a M.Sc in Naval Architecture and Marine Engineering (achieved at Chalmers University in Sweden) would act in this way and be so ignorant of fairly basic physics and mathematics.
http://heiwaco.tripod.com/cv.htm

Is it possible to see if he was an alumnus in 1969?

[Echnaton]

Can you really show by engineering calculations that you can slow down a 43.5 ton space ship from 2 400 to 1 500 m/s speed in space by burning 10.8 ton fuel at 30 kg/s producing a 97 400 N force?

Or that a 5.6 ton module of thin plates/stiffeners arriving into Earth's atmosphere at 11 200 m/s speed is slowed down by friction turbulence to 100 m/s speed during 18 minutes without heating up the inside at all? A few centimeters away the air is glowing hot, the heat shield is at 1600°C and inside - 20°C!

The facts of Apollo are on record and widely accepted by the relevant experts.  The  burden of proof is on you to show that it was not possible and to provide an alternate hypothesis to explain the observations.  Your challenge gimmick does not relive you of this burden, so stop dodging.

[Andromeda]

I didn't want to do this.

Heiwa

The European Maritime Safety Agency (EMSA) is a European Union agency charged with reducing the risk of maritime accidents, marine pollution from ships and the loss of human lives at sea by helping to enforce the pertinent EU legislation.

I wrote to EMSA a few days ago.  Not only did they say Heiwa Co was not in any way connected with them, or European maritime safety, but they had never even heard of Heiwa Co.

You are acting fraudulently, yet you froth and foam with rage while launching accusation at others.  Do you see why we are having problems?

I'm finding it difficult to believe that someone who has a M.Sc in Naval Architecture and Marine Engineering (achieved at Chalmers University in Sweden) would act in this way and be so ignorant of fairly basic physics and mathematics.
http://heiwaco.tripod.com/cv.htm

Is it possible to see if he was an alumnus in 1969?

And why would it take 4 years?

[Zakalwe]

And why would it take 4 years?

Engineering degrees generally take 4 years or more in Europe.

[Abaddon]

... I therefore suspect that Heiwa believes the spacecraft had to gradually change attitude during the burn to keep the engine pointed in the direction of travel.

Well, it didn't. The spacecraft was aimed in a particular direction for the burn, and remained pointed in that direction for the duration of the burn.

In post #786 the question was about how much fuel was used (to produce a force) in order to just slow down a space ship to get into Moon orbit or to the speed up the space ship to get out of Moon orbit. Nobody seems to know the answer as no replies have turned up.

Another question is evidently in what direction this force is applied during the speed change maneuver. And for how long.

To get into Moon orbit you must, apart from slowing down, change course from a straight one into an elliptical/circular one around the Moon and Moon gravity will assist. Peter B suggests that during a 6 (or eight) minutes burn (30 kg/s fuel burnt) applying 97 400 N force in one particular direction suffices.

It is a complicated maneuver in 3-D. The inertia force of the space ship is applied in one direction, Moon gravity pulls in another direction (I assume the trajectorey is already curved due to Moon gravity) and then you apply a third force - the brake force - in a third, particular direction while losing 10 800 kg mass in the SM ... that you keep steady all the time? If the brake force is not in the direction of travel, it will evidently also change the direction.

There is then quite a number of factors to keep an eye on. Just how to keep the space ship stable in one - the right - direction during 6 minutes braking/turning, while you loose 10 800 kg mass (30 kg/s) is complicated. Imagine if the space ship tips over and goes away in the wrong direction ... and you have no fuel left or means to correct it.

So I am happy, Peter B, that you have pointed out that the brake force cannot be applied in the direction of travel but in another particular direction where it is held steady when the space ship changes direction and looses mass and slows down. You are a genious.

Now tell me how much fuel you need to slow down!  

I checked the numbers and 10,800 Kg looks on the money.
I will split the million with Peter B.

[Noldi400]

Let me after about 785 posts remind you about topic, i.e. my Challenge about safety of space travel and associated fuel consumption. You have to demonstrate how to travel to the Moon and back to win the prize (€1M). It is not easy.

Say that your space ship has mass 32 676 kg excluding fuel and that you must slow down from 2 400 to 1 500 m/s velocity to insert into Moon orbit. Your space ship has a P-22 KS rocket engine with 97 400 N thrust (at full blast). How much fuel do you require to carry out the braking maneuver?

If you suggest, e.g. 10 898 kg, you must support your answer with proper calculations to win the prize (€1M). I have a feeling you need >80 000 kg.

OK, let's work through that. This will be simple math as - once again - I'm not an engineer and my math skills aren't that deep. Despite your comments, Tsiolkovsky gives us all we need.

BTW, without a time frame thrust is pretty much irrelevant - since we're talking about Apollo, I'm going to assume a P22K AJ10-137   rocket engine with an exhaust velocity of 3079 m/s.

So. The Rocket Equation:

Delta-V = EV * ln(m₀/m₁)

Where m₀ = Total mass before the burn
          m₁ = mass after the burn
          ln = natural logarithm
          EV = exhaust velocity

So, let's plug in the figures and solve for the difference between m₁ and m₀, which will be the fuel used to produce the desired change in velocity.

Delta-V = 2400 - 1500 = 900 m/s change in velocity.

900 m/s = 3079 m/s *  ln(m₀/32676)   ; divide both sides by 3079 (units cancel out)

0.2923 =  ln(m₀/32676)                       ; take the inverse ln of each side

1.3395 = m₀/32676                             ; multiply both sides by 32676

43769.5 = m₀                                      ; which gives us the mass before the burn...

43769.5 - 32676 = 11093.5                                   ; subtract the mass of the spacecraft and voila!
                                                                           ; we get the amount of mass expended.

And there's your answer, arrived at using the figures you provided and some ninth grade math.

Some of you professional number-crunchers want to check my work, please?

[Andromeda]

And why would it take 4 years?

Engineering degrees generally take 4 years or more in Europe.

Chalmers website says their MSc programmes are currently 2 years long?

[Andromeda]

The maths looks good to me, Noldi400.

[Zakalwe]

And why would it take 4 years?

Engineering degrees generally take 4 years or more in Europe.

Chalmers website says their MSc programmes are currently 2 years long?

Perhaps he was held back a couple of times? 

[Abaddon]

It has been repeatedly demonstrated how Apollo went to the Moon and back.

Yes, it has in several reports that I use as reference - see link in post #1. I evidently do not believe these reports and therefore we have this friendly discussion. Let's keep it that way.

See, e.g. my post #786. Can you really show by engineering calculations that you can slow down a 43.5 ton space ship from 2 400 to 1 500 m/s speed in space by burning 10.8 ton fuel at 30 kg/s producing a 97 400 N force?

Expending that fuel gives a delta v of 1018 m/s, so also on the money. Where's my million?

[ka9q]

43769.5 - 32676 = 11093.5                                   ; subtract the mass of the spacecraft and voila!
                                                                           ; we get the amount of mass expended.

And there's your answer, arrived at using the figures you provided and some ninth grade math.

Some of you professional number-crunchers want to check my work, please?

Looks right to me for the specific numbers provided. Note that they're not the actual figures for the Apollo 11 mission.

Please wire me my share of the prize money.