No crater under LEM 9982 lbs engine?!

[trodas]

No crater under LEM?!

( http://upload.wikimedia.org/wikipedia/comm...S11-40-5921.jpg )

This is example how a rocket engine - Armadillo LOX/Alcohol small rocket engine with thrust only 500 lbf:

vid: http://media.armadilloaerospace.com/2005_0...0/allHovers.mpg
rapid: http://rapidshare.com/files/260334954/Arma...0lbf_rocket.mpg
YouTube: http://youtube.com/watch?v=mHuhtS3658o

So, a 500 lbs rocket engine can do THIS?! Can blast a small crater in solid CONCRETE?! (second try) Now what can do a 9 982 lbs rocket engine of the Apollo LEM? ( http://en.wikipedia.org/wiki/Apollo_Lunar_Module )
And with a light regolit dust, to witch is possible engrave foot-marks so easily!

A very good explaination of the hoax is here:
http://youtube.com/watch?v=yEQNZQdJFtI
http://youtube.com/watch?v=Nz5sfwyvAK0
http://youtube.com/watch?v=_tTAK77Df7w
http://youtube.com/watch?v=GGh_t_cpEI0
http://youtube.com/watch?v=NsnJSwKol68

...but I think the presented evidence itself is more that enought.

[Swift]

trodas,
A few friendly pieces of moderator advice (this is not a warning, at least yet).

First, this has been discussed multiple times here. A little bit of searching will find this. This is not a new item.

Second, IIRC, you already have multiple discussions going in other threads. You might want to make sure you've addressed any outstanding questions in those threads - you are required to answer direct questions put to you if you are advocating a conspiracy theory - if that is news to you, you need to read the rules and the Advice for CT supporters.

Third, if you want to have a serious discussion about this, you might want to lose the in the thread title. It makes it look like you are just pulling our chains.

[LaurelHS]

Do you plan on returning to your Serious problem with the stars thread and addressing people's responses there? The same question goes for your Shadow length in LRO images thread. People on this board tend not to like hit-and-run posters.

[Van Rijn]

Old claim with many problems, including the suggested thrust at landing.

See here:

http://www.clavius.org/techcrater.html

[Gawdzilla]

I have some time to waste, so:


WHAT did the engine do to "solid" concrete, please? And what is the hardness of "solid" concrete, a mix of cement and sand, versus that of the lunar rock?

AND, how long, in real minutes, was the full force of the rocket focus on that one area of concrete? The LEM arrived laterally as well as vertically.

[slang]

Man, if you put the same amount of effort that you put into compiling this post into reading all responses to your other posts, I'm sure you would already have found the answer to this question. Clavius.org for all your regular hoax claims.

[pzkpfw]

Can someone explain why I don't leave skid-marks every time I stop my car?

[kleindoofy]

Can someone explain why I don't leave skid-marks every time I stop my car?

Stop driving like a wuss and you will.

[slang]

Can someone explain why I don't leave skid-marks every time I stop my car?

You might... if you stop your car in a really scary situation.. I'll leave the details to the imagination. And apologize for that.

[sohh_fly]

This is like a scene from the twilight zone.
A whole lot of imagination,now where's the reality?

Trodas: you still have so many question's to answer,but I suspect it's all hit and run's.And I'm not talking baseball either.

[Dave J]

Shoot, trodas, I can burn a hole throigh a 1/32" steel plate in under a second with an Estes A8-3. Doesn't have diddly to do with the throttled down LM descent engine landing on a dusty/rocky lunar surface, but neither does your demonstration.

[Glom]

First off, the LM DPS had a throttle. Look up the actual thrust at touchdown before making irrelevant comparisons.

[Gawdzilla]

Actually, Ralph Rene's footage from P&T helps make the point. He blows away the layer of dust and pebbles on the concrete, but doesn't pit the underlying material at all. Thanks, Ralph.

[JayUtah]

...

So, a 500 lbs rocket engine can do THIS?! Can blast a small crater in solid CONCRETE?!

Nope.

Where did you study engineering? Please provide an answer.

What you see is not the plume digging a hole in solid concrete, but rather the concrete responding to the heat load by spalling. This is a well-known property of concrete, familiar to engineers. If you apply a significant localized heat load to concrete, the aggregate particles expand at different rates and mechanically fracture the concrete. That's what you see here.

I can recreate the identical effect with my oxyacetylene torch, which produces almost no thrust. It will, however, cause any concrete surface to which I expose its flame to spall violently. If you see spots along the freeway were cars have caught fire, you may also see spalling effects on the roadway and guard rails. Burning cars produce no thrust, but they do indeed create a sufficient radiant and direct heat load to spall the concrete.

Your value for the DPS thrust is incorrect.

The LM DPS plume temperature is clearly below that of incandescence. This is consistent with the expectations associated with underexpanded nozzles and the well-studied thermal principles of plumes. Since the EM emissions from plumes provide a means of tracking rocket-propelled vehicles, and since the military is leaning more toward rocket propulsion for ordnance delivery, the physics of plume temperature are a matter of extreme interest to the industry.

Why do you suppose there are no qualified rocket scientists who subscribe to the silly notion that the DPS exhaust plume effects are somehow unexpected?

[Daryl71]

Trodas, perhaps you could explain to us why the two 110,000-pound thrust GE90-110B1 turbofans on the Boeing 777F don't vaporize baggage handlers hundreds of feet away from the plane and melt runways at full thrust. If a rocket engine generating 2,600 pounds of thrust (that's about 1.2 PSI of pressure at the nozzle exit, not counting the effects of vacuum dispersal) could dig out a "charred blast crater" while moving laterally over the lunar surface, it's not much of a stretch, is it?

[cjameshuff]

Lets see...

There's the fact that it hovered over the same spot for about 15-20 seconds before the concrete started to popcorn...and as for the thrust difference, it was hovering in a 1 g field, not descending in a 1/6 g field. What was the throttle setting of the lunar lander at that point, and how long did it hover at a comparable distance over the ground before setting down?.

There's also the fact that it was done in an atmosphere, reducing the expansion of the gases and thus increasing the temperature and density of the gases hitting the ground...in vacuum, you can get both more thrust and a lower exhaust temperature out of a rocket, due to the higher expansion.

There's the fact that concrete is a hydrated material, and there was likely also free water in the pavement there...it'd never totally dry, due to sitting on moist ground and being exposed from the weather. So not only was there thermal expansion, there was volume changes from dehydration, weakening of the hydrated cement, and steam pressure building up in voids inside...so the concrete did what it typically does when it gets hot enough. In contrast, the lunar surface below the generally thin loose dust layer was fairly solid volcanic rock with a water content lower than any on Earth.

Also note that the rocket exhaust can't even reliably knock those stands over, despite them being apparently a bit top heavy and having big flat areas to catch the blast (they look rather like they're supposed to fall over and out of the way, actually). The popcorning concrete in fact shoots upwind into the rocket exhaust, and continues to pop upward after the rocket shuts down...it's clearly not being carved out by the force of the jet.

[captain swoop]

Harrier Jets land on grass and it doesn't even get singed, In fact when they take off the grass is undamaged.

[Gawdzilla]

Harrier Jets land on grass and it doesn't even get singed, In fact when they take off the grass is undamaged.

However, they have been seen to make the flight deck on an LHA kind of saggy.

[JonClarke]

However, they have been seen to make the flight deck on an LHA kind of saggy.

Evidence? The Spanish operated Harriers of a carrier with a wooden flight deck for many years without a problem.

Jon

[SquantoTerror]

Evidence? The Spanish operated Harriers of a carrier with a wooden flight deck for many years without a problem.

Jon

True, though the landing area of the Dédalo's flight deck was metal.

[Gawdzilla]

Evidence? The Spanish operated Harriers of a carrier with a wooden flight deck for many years without a problem.

Jon

Just empirical. I was stationed on the Peleliu.

[JonClarke]

Just empirical. I was stationed on the Peleliu.

Cool!

was it the exhaust efflux though, or the concentrated weight of an aircraft?

Jon

[captain swoop]

Well the 3 RN 'Invincibles' haven't had a problem.

[Gawdzilla]

Cool!

was it the exhaust efflux though, or the concentrated weight of an aircraft?

Jon

I was in the Engineering Dept., and worked with the yard birds as they were planning on how to reinforce a section of the deck for Harrier landings. I asked them if a helo full of grunts wasn't heavier than a Harrier? They replied, "It's not the weight, it's the exhaust. It creates problems for a deck this thin."

[JonClarke]

I was in the Engineering Dept., and worked with the yard birds as they were planning on how to reinforce a section of the deck for Harrier landings. I asked them if a helo full of grunts wasn't heavier than a Harrier? They replied, "It's not the weight, it's the exhaust. It creates problems for a deck this thin."

So it would be the concentrated pressure of the exhaust plume, not the heat then?

Ironic that the WWII vintrage carrier with its wooden flight deck the Spanish flew Harriers off for many years was less effected.

An OT question, since the LHAs were the second generation of USN ships to operate the Harrier I would have thought they would have been built with the deck already reinforced.

Jon

[grant hutchison]

So it would be the concentrated pressure of the exhaust plume, not the heat then?

At the hover, the exhaust plumes are carrying the same weight as the undercarriage of a parked Harrier. I'd guess that they distribute that weight over a wider area than the tyres do, even when close to landing. So if the parked Harrier doesn't bend the deck, the pressure of the exhaust plumes shouldn't either. I'd therefore guess that heat must have something to do with it.

Grant Hutchison

[Gawdzilla]

So it would be the concentrated pressure of the exhaust plume, not the heat then?

Ironic that the WWII vintrage carrier with its wooden flight deck the Spanish flew Harriers off for many years was less effected.

An OT question, since the LHAs were the second generation of USN ships to operate the Harrier I would have thought they would have been built with the deck already reinforced.

Jon

I think they were concerned about extended hover, not just normal landings. I was transfered before any mods were made, however.

The LHAs were a disaster, IMNSHO. Lytton Industries really messed up the build. For example, the automated power plants. They were designed to allow two men to run the entire plant remotely. This didn't work on LHA-1, so they removed it. While they were removing it, they were installing it on LHA-3. Then they removed it from LHA-3. While they were removing it from LHA-3 they were installing it on LHA-5.

[captain swoop]

Getting a bit OT now.

[Gawdzilla]

Getting a bit OT now.

Sowwy.

So, does anybody have the numbers for the amount of blast that would be needed to spall the regolith? Seems that would be important in considering what types of engines could and could not leave a mark.

[cjameshuff]

So, does anybody have the numbers for the amount of blast that would be needed to spall the regolith? Seems that would be important in considering what types of engines could and could not leave a mark.

Well, as mentioned before, it was the heat, not the blast...you could see bits of concrete popping upward, into the blast, and the stands only got pushed around a bit, they didn't even topple over reliably. Normal winds exert more force on objects and people walking around outside than that thing did on the ground beneath it. Maximum 500 lbf thrust (less in reality, since it was hovering)...call the impingement area 1.5 ft square...the additional pressure exerted by the exhaust was about 0.1 atm. There's turbulence and uneven distribution, sure, but it's clearly still not enough to be the cause of the damage here. The descent stage's engine was capable of producing higher thrust, but it was also operating at low throttle and in vacuum. The exhaust was expanded through a larger bell to obtain more thrust, and expanded more before hitting the ground due to the lack of an atmosphere. You can see this effect in many rocket launch clips...the exhaust forms a column with straight or inward-sloping sides at low altitude, but balloons out to the sides at higher altitude. Greater expansion leads to lower temperatures and pressures.

Portland cement's a hydrate. It hardens mostly due to water binding to salts (calcium sulfate and calcium silicate, mostly), and recrystalizing to form a solid mass. Expose it to strong heat, and you reverse the process...the cement holding the concrete together starts converting to weaker, powdery anhydrous salts, steam and stresses from thermal expansion build up, and it goes pop.

Moon rock is about as anhydrous as you can get, so it won't popcorn like that. With strong enough heating on a portion of solid rock, you might get cracking due to thermal shock with some chips thrown off, but the less solid breccias seem unlikely to behave that way. You would need a concentrated blast to break the material apart and remove it from the area to get a crater. It would be a hard thing to give numbers for even with detailed data on the ground under the landers, but it would almost have to be designed for excavation rather than thrust...no expansion bell, but a nozzle to force high pressure, high temperature gases into the forming crater.