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Annie - I am not martyn. I don't even know who martyn is except I gather he was on this forum once. Who is being paranoid?

LN



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LordNibbler wrote:Annie - I am not martyn. I don't even know who martyn is except I gather he was on this forum once. Who is being paranoid?

LN


So it was not an accusation it was a question ?...all you had to say was NO I am not Martyn ....
but all the Drama ....."so now I am being accused of being someone " why that reaction to a very simple straight forward question ?? :confused:
you mentioned "we had discussed this before" in a post but you just joined so how could we of ???? :confused: :chin:
and that is why I thought you may of been an old poster under a new name ....its not rocket science :rofl:




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Let me explain the blast crater point as it is quite a simple thing.

There are various factors that contribute towards the small blast crater (which is still easily visible in the A11 photo).

Firstly, as Wotsit correctly says, the engine was actually switched off before touch-down. It was meant to be switched off the moment the contact light illuminated in the cabin. The contact probes were at least one metre long given their relative size to the landing pads which were one metre diameter.

The engine was switched off early to prevent the engine bell from rupturing by pressure buildup as the bell got close to the ground. Although I don't fully understand why they needed to prevent this given that particular engine was not used again, I gather there was also an element of pride amongst the pilots in that none of them cracked the bell on touch-down. Maybe if pressure buildup was sufficient enough to crack the bell, it might also damage the underside of the lander?

Next, the lander was actually descending slowly in one sixth g so the energy needed from the engine was one sixth that needed on Earth.

Next, there is no atmosphere on the moon so the blast forces from the engine are not distributed by surrounding air mass. This is why the blast crater is localised and not spread out.

I think that on all landings, the lander was also moving laterally at the point of touch down. This can be seen in some photos by looking at the landing pads and contact probes which shows movement across the soil. The effect of lateral movement when combined with the engine being switched off early is of course to further diffuse the blast crater.

All the pilots reported back on the depth of the blast crater. I can't remember the exact figures but I think it was described as being in the region of 4 to 6 inches. You can't really tell from the photo what the depth is. The depth would also have been limited by the depth of the lunar soil as below that was rock. Again, I'm not sure on the regolith depth but when they started to plant the pole for the flag, they soon ran into difficulty so it wasn't that deep. On some later missions when drilling core samples, they actually had to abandon them because they couldn't get the drill in more than a few inches.

Anyway, put all those facts together and it is quite understandable why the landers didn't blast out a crater we might expect to see (any comparisons with an impact crator or bomb crator are totally wrong).

Comparing the blast effect of the landing with the take-off is not comperable. At take off, the engine is having to put out enough energy to get a heavy object moving and moving fast as the lander had to reach lunar orbit. As everyone knows, the most difficult part is to get something moving so the engine was having to pump out considerably more energy at take off than it was at landing. It was also a different type of engine using a different type of fuel which might have contributed to visible effect (although I'm not sure on that point, other than the colour of the flame). Next time you fly off for your holidays, compare the energy needed to get the plane flying to that needed to get the plane landed - it isn't a perfect analogy but at least gives you an example.

Hopefully, that was informative :)

LN



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and 10 days nearly till Santa flies down my chimmney and leaves me presents ....gosh I hope he does not leave too much soot on my floor :D
Doncha just love this stuff !! :D




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LordNibbler wrote:Let me explain the blast crater point as it is quite a simple thing.

There are various factors that contribute towards the small blast crater (which is still easily visible in the A11 photo).


I can easily see it on the Apollo 12 pic, but not on any of the Apollo 11 pics


Firstly, as Wotsit correctly says, the engine was actually switched off before touch-down. It was meant to be switched off the moment the contact light illuminated in the cabin. The contact probes were at least one metre long given their relative size to the landing pads which were one metre diameter.

The engine was switched off early to prevent the engine bell from rupturing by pressure buildup as the bell got close to the ground. Although I don't fully understand why they needed to prevent this given that particular engine was not used again, I gather there was also an element of pride amongst the pilots in that none of them cracked the bell on touch-down. Maybe if pressure buildup was sufficient enough to crack the bell, it might also damage the underside of the lander?

Next, the lander was actually descending slowly in one sixth g so the energy needed from the engine was one sixth that needed on Earth.

Next, there is no atmosphere on the moon so the blast forces from the engine are not distributed by surrounding air mass. This is why the blast crater is localised and not spread out.


There is no atmosphere of course but the gases from the engine are there. I still would expected more disturbance.



I think that on all landings, the lander was also moving laterally at the point of touch down. This can be seen in some photos by looking at the landing pads and contact probes which shows movement across the soil. The effect of lateral movement when combined with the engine being switched off early is of course to further diffuse the blast crater.

All the pilots reported back on the depth of the blast crater. I can't remember the exact figures but I think it was described as being in the region of 4 to 6 inches. You can't really tell from the photo what the depth is. The depth would also have been limited by the depth of the lunar soil as below that was rock. Again, I'm not sure on the regolith depth but when they started to plant the pole for the flag, they soon ran into difficulty so it wasn't that deep. On some later missions when drilling core samples, they actually had to abandon them because they couldn't get the drill in more than a few inches.

Anyway, put all those facts together and it is quite understandable why the landers didn't blast out a crater we might expect to see (any comparisons with an impact crator or bomb crator are totally wrong).

Comparing the blast effect of the landing with the take-off is not comperable. At take off, the engine is having to put out enough energy to get a heavy object moving and moving fast as the lander had to reach lunar orbit. As everyone knows, the most difficult part is to get something moving so the engine was having to pump out considerably more energy at take off than it was at landing.


But for an equal mass you need just as much energy to get something to stop as to get it going. And ....... the mass of the object that takes off is much lighter than what landed. So you'd expect actually less power on take off



It was also a different type of engine using a different type of fuel which might have contributed to visible effect (although I'm not sure on that point, other than the colour of the flame). Next time you fly off for your holidays, compare the energy needed to get the plane flying to that needed to get the plane landed - it isn't a perfect analogy but at least gives you an example.


I think a harrier jump jet would be a better example. On landing you are pushing against gravity to stop, on take off you are pulling away from gravity to move.


Hopefully, that was informative :)

LN



Yup. :) - Although maybe Apollo 11 was faked and Apollo 12 was real. :) :)

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What if .....just what if ....we have all been squabbing for years over crap ....and while we are squabbling other things are going on ???? I like to keep all options open ....this interview is facinating ..






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smeggypants wrote:I can easily see it on the Apollo 12 pic, but not on any of the Apollo 11 pics


But you can still see the change in colour of the soil where the engine disturbed it.

There is no atmosphere of course but the gases from the engine are there. I still would expected more disturbance.


Well, as I already said, the engine was off at least one metre above the ground which coupled with fact it wasn't working very hard (see next point) in one sixth g lessens the disturbance.

But for an equal mass you need just as much energy to get something to stop as to get it going. And ....... the mass of the object that takes off is much lighter than what landed. So you'd expect actually less power on take off


It wasn't the engine that generated the stopping forces, it just slowed it down. The stopping was actually done by the moon itself! They landed at a couple of feet per second purely under the effect of lunar gravity, not at zero feet per second under engine power so the impact of the landing pads on the soil is what actually stopped the craft. The engine was not providing that energy.

At take off, yes they had a lighter load but the engine is still having to work harder than the landing because firstly it is having to get a static load moving against the force of gravity whereas the landing engine was just slowing it down and not stopping and secondly, because the speed of lift off was considerably higher than the speed of landing. It would be interesting to do the maths for this but I don't know what formula is the correct one.

I think a harrier jump jet would be a better example. On landing you are pushing against gravity to stop, on take off you are pulling away from gravity to move.


Yes, that is a much better example.

There are two factors why I think take off or more energy consuming than landing.

First as stated, a lot of the energy of landing is taken by the ground unless the pilot controls an absolutely perfect landing at zero f/sec. From memory, when a Harrier lands, it drops the last few inches. The important point though is that as he is descending, he is using the force of gravity but is providing partial lift against it, ie, he doesn't need to generate enough energy to overcome gravity.

Secondly, for take off, you are having to provide all the energy and enough energy to exceed the force of gravity as well as provide the speed of take off. This has to be more energy than landing.

Yup. :) - Although maybe Apollo 11 was faked and Apollo 12 was real. :) :)
[/quote][/quote]

:)

Ironically, 12 is the one where they've hardly got any TV film coverage because one the astronauts pointed the camera at the sun and burnt out the tube.

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annie27 wrote:
LordNibbler wrote:Annie - I am not martyn. I don't even know who martyn is except I gather he was on this forum once. Who is being paranoid?

LN


So it was not an accusation it was a question ?...all you had to say was NO I am not Martyn ....
but all the Drama ....."so now I am being accused of being someone " why that reaction to a very simple straight forward question ?? :confused:
you mentioned "we had discussed this before" in a post but you just joined so how could we of ???? :confused: :chin:
and that is why I thought you may of been an old poster under a new name ....its not rocket science :rofl:



:D :D :D gosh you would of liked Martyn a really nice lad but who always managed to avoid questions that were awkward by ignoring them and changing the conversation ...but like a said a really nice lad ! :)




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LordNibbler wrote:
smeggypants wrote:I can easily see it on the Apollo 12 pic, but not on any of the Apollo 11 pics


But you can still see the change in colour of the soil where the engine disturbed it.



Sort of but it doesn't look disturbed



LordNibbler wrote:
There is no atmosphere of course but the gases from the engine are there. I still would expected more disturbance.


Well, as I already said, the engine was off at least one metre above the ground which coupled with fact it wasn't working very hard (see next point) in one sixth g lessens the disturbance.

But for an equal mass you need just as much energy to get something to stop as to get it going. And ....... the mass of the object that takes off is much lighter than what landed. So you'd expect actually less power on take off


It wasn't the engine that generated the stopping forces, it just slowed it down. The stopping was actually done by the moon itself! They landed at a couple of feet per second purely under the effect of lunar gravity, not at zero feet per second under engine power so the impact of the landing pads on the soil is what actually stopped the craft. The engine was not providing that energy.



Fair point. but surely they wouldn't have wanted to land with any significant 'bump' otherwise it might have damaged something?


At take off, yes they had a lighter load but the engine is still having to work harder than the landing because firstly it is having to get a static load moving against the force of gravity whereas the landing engine was just slowing it down and not stopping and secondly, because the speed of lift off was considerably higher than the speed of landing. It would be interesting to do the maths for this but I don't know what formula is the correct one.


Yeah I'd like to see some maths on it. I suppose if you knew all the masses of the craft and the speed is touched down at it wouldn't be that difficult



I think a harrier jump jet would be a better example. On landing you are pushing against gravity to stop, on take off you are pulling away from gravity to move.


Yes, that is a much better example.

There are two factors why I think take off or more energy consuming than landing.

First as stated, a lot of the energy of landing is taken by the ground unless the pilot controls an absolutely perfect landing at zero f/sec. From memory, when a Harrier lands, it drops the last few inches. The important point though is that as he is descending, he is using the force of gravity but is providing partial lift against it, ie, he doesn't need to generate enough energy to overcome gravity.

Secondly, for take off, you are having to provide all the energy and enough energy to exceed the force of gravity as well as provide the speed of take off. This has to be more energy than landing.

Yup. :) - Although maybe Apollo 11 was faked and Apollo 12 was real. :) :)


:)

Ironically, 12 is the one where they've hardly got any TV film coverage because one the astronauts pointed the camera at the sun and burnt out the tube.

LN


Dumbass!! I bet they threatened to leave him there!!! :rofl: :rofl: :rofl:

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Drop ????I think not




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annie27 wrote:Drop ????I think not


It's the suspension/shock absorbers in the landing gear does the final act of bringing it to a stop. This is Nibbler's point. Same behaviour as in the moon lander

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smeggypants wrote:
annie27 wrote:Drop ????I think not


It's the suspension/shock absorbers in the landing gear does the final act of bringing it to a stop. This is Nibbler's point. Same behaviour as in the moon lander


so let me get this straight ....its not the downward propulsion of the engines that helps it land and stabilise ????
wow all that science education gone to waste ..... ;) :D




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annie27 wrote:
smeggypants wrote:
so let me get this straight ....its not the downward propulsion of the engines that helps it land and stabilise ????
wow all that science education gone to waste ..... ;) :D


Yes it is up to the last section of it's travel. It would be a waste of fuel to hover the craft so it's velocity is zero right at the point of touchdown. This is especially important for a moon landing when every ounce of mass counts. You use the friction of the landing gear shock absorption instead of fuel

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smeggypants wrote:
annie27 wrote:
smeggypants wrote:
so let me get this straight ....its not the downward propulsion of the engines that helps it land and stabilise ????
wow all that science education gone to waste ..... ;) :D


Yes it is up to the last section of it's travel. It would be a waste of fuel to hover the craft so it's velocity is zero right at the point of touchdown. This is especially important for a moon landing when every ounce of mass counts. You use the friction of the landing gear shock absorption instead of fuel


what a load of BUNK ......if that was true it would be used today ...did you hear the bloody noise of those engines ...you could feel the pressure ....sorry ..its just not working for me the dust would have been everywhere
and I assume floated since there is no gravity to pull it back down ????? :thumb: but the pics on the moon are crystal clear no dust suspended ... ;)




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annie27 wrote:
smeggypants wrote:
annie27 wrote:
smeggypants wrote:
so let me get this straight ....its not the downward propulsion of the engines that helps it land and stabilise ????
wow all that science education gone to waste ..... ;) :D


Yes it is up to the last section of it's travel. It would be a waste of fuel to hover the craft so it's velocity is zero right at the point of touchdown. This is especially important for a moon landing when every ounce of mass counts. You use the friction of the landing gear shock absorption instead of fuel


what a load of BUNK ......if that was true it would be used today ...did you hear the bloody noise of those engines ...you could feel the pressure ....sorry ..its just not working for me the dust would have been everywhere
and I assume floated since there is no gravity to pull it back down ????? :thumb: but the pics on the moon are crystal clear no dust suspended ... ;)



It's not bunk


And every object that has mass has gravity. It's a fundamental law of the universe. The bigger the mass the bigger the gravitational force it exerts. The moon has 1/6th of the gravity of the Earth.

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smeggypants wrote:
annie27 wrote:
smeggypants wrote:
annie27 wrote:
smeggypants wrote:
so let me get this straight ....its not the downward propulsion of the engines that helps it land and stabilise ????
wow all that science education gone to waste ..... ;) :D


Yes it is up to the last section of it's travel. It would be a waste of fuel to hover the craft so it's velocity is zero right at the point of touchdown. This is especially important for a moon landing when every ounce of mass counts. You use the friction of the landing gear shock absorption instead of fuel


what a load of BUNK ......if that was true it would be used today ...did you hear the bloody noise of those engines ...you could feel the pressure ....sorry ..its just not working for me the dust would have been everywhere
and I assume floated since there is no gravity to pull it back down ????? :thumb: but the pics on the moon are crystal clear no dust suspended ... ;)



It's not bunk


And every object that has mass has gravity. It's a fundamental law of the universe. The bigger the mass the bigger the gravitational force it exerts. The moon has 1/6th of the gravity of the Earth.


oh I see ..so the dust just settled ......producing crystal clear pictures almost like a night in the desert :D




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annie27 wrote:
oh I see ..so the dust just settled ......producing crystal clear pictures almost like a night in the desert :D


Well yes it would do. And even though there's only 1/th ofthe gravity there's no air resistence on the moon so the dust would settle just as quickly as dropping a heavy object from teh same height.

They did do the dropping the feather and hammer experiment on the moon ....





To fake that they would have had to have a rather large chamber as a vacuum

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smeggypants wrote:
annie27 wrote:
oh I see ..so the dust just settled ......producing crystal clear pictures almost like a night in the desert :D


Well yes it would do. And even though there's only 1/th ofthe gravity there's no air resistence on the moon so the dust would settle just as quickly as dropping a heavy object from teh same height.

They did do the dropping the feather and hammer experiment on the moon ....





To fake that they would have had to have a rather large chamber as a vacuum


I guess you are not a fan of David Blaine then ....this proves nothing ....there is footage of the wires attached to the leaping astronauts glinting a hammer would be a chump change challenge ....
they lie about war they lie about weather they lie about swine flu ....they just lie ...
I think there is far more going on on the moon than we will ever know .....
so I guess this has to be over ....I have moved on to the the next level of my existance ....
I dont believe in God ...and I dont believe in Darwin either ....... :)




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annie27 wrote:....this interview is facinating ..



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annie27 wrote:[

I guess you are not a fan of David Blaine then ....this proves nothing ....there is footage of the wires attached to the leaping astronauts glinting a hammer would be a chump change challenge ....
they lie about war they lie about weather they lie about swine flu ....they just lie ...
I think there is far more going on on the moon than we will ever know .....
so I guess this has to be over ....I have moved on to the the next level of my existance ....
I dont believe in God ...and I dont believe in Darwin either ....... :)


how did they get a feather to fall atthe same time as a hammer in an atmosphere?

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