This part talks about the electrical power sub-system of the lunar module.
It is described in the part 5 of the lunar module handbook.
Link to the LM handbook
They say:
"Ground return in the LM is generally accomplished through the metal structure, whereas ground return in the command module is isolated from the command module structure".
The problem is that, when the LM is docked to the command module, and the command module provides power to the LM, the metal structure of the LM makes a contact with the metal structure of the command module, which means that the ground return of the LM is also the metal structure of the command module.
This is the schema of the battery voltage and current monitoring circuit.
An amperemeter, circled in red, measures the current which is going through; about this amperemeter, they say this:
"The indicator scale is graduated from 0 to 120 amperes, although the input signal is of considerably smaller amplitude".
Indeed, the current which goes through cannot be greater than 2 amperes, for it goes through a 2 amperes fuse I have circled in red.
Using a scale from 0 to 120 amperes to measure a current smaller than 2 amperes makes no sense.
The indication which is read on this amperemeter will be less than precise, meaningless.
Now, an Apollo believer has pointed out to me that there was a branch going on the left, and that the important current could come from this branch.
So, I looked what was on the left, and I saw that it was going to a rotary switch; all the contacts of this rotary switch pass through 1/8 AMP fuses; I show two of them circled with orange, but the other contacts also come from such fuses.
So, even from the left branch, an important current cannot come which would justify the use of an amperemeter graduated up to 120 amperes.
This is the schema of the primary bus voltage monitoring circuit.
An OR gate, I have circled in orange, receives three signals which indicate whether the voltage is less than 112 volt, or its frequency is less than 398 cps or greater the 402 cps, and in one of these events , its output is set to 1 and energizes a relay which sets on a caution light.
The alternating current is sent through converters which convert it, one its voltage to a DC current, and the other one its frequency to a DC current.
But these converters only make a conversion work, they don't make a comparison of the voltage they produce with voltages corresponding to the controls which are to be made (i.e. the voltage of the alternating current must not fall under 112 volts, and its frequency must remain comprised between 398 and 402 cps).
There are comparators missing after these converters to make these comparisons.
In this modified circuit, I have added the comparators which are missing, and which allow to make the necessary controls.
A voltmeter allows to measure the voltage of one of the signals arriving on a rotary switch.
Each of these signals is comprised between 0 and 5 volts, which means that, whatever the position of the rotary switch, the signal which goes through the voltmeter is also comprised between 0 and 5 volts.
The problem is that this voltmeter is graduated from 20 volts to 40 volts.
Explain me how a voltmeter which is graduated between 20 and 40 volts can indicate a voltage which is under 5 volts?
This is the schema of the malfunctioning battery isolation circuitry.
An OR gate, I have circled in red, receives all the malfunction outputs of the batteries, one input per battery malfunction.
For instance, the malfunction output of the Battery 2 (colored in orange) goes into one input of the OR gate, and the malfunction output of the Battery 3 (colored in violet) also goes into a different input of the OR gate.
If one of the two malfunction outputs goes high, the output of the OR gate will also go high and set a caution light on.
Now, what is abnormal is that the malfunction outputs of the Batteries 2 and 3 are connected together (by the connection I have colored in red), when they should go separately into inputs of the OR gate.
The result is that, if one of the malfunction outputs is low, it will force to low the other malfunction output it is connected to, even though the latter should go high, thus preventing the output of the OR gate from going high and setting the caution light on.
This is the schema of the command module/lunar module primary transfer logic.
They say this about this logic:
To transfer the power on the lunar module from the lunar module internal power to the command module power:
- The command module disactivates the lunar module power.
- The command module initiates the command module power to the lunar module.
Conversely, to transfer the power on the lunar module from the command module power to the lunar module internal power:
- The command module disactivates the command module power to the lunar module.
- The command module initiates the lunar module power on.
The command module disactivating LM power means that the switch I have circled in red is changed position.
The switch is now on the low position, but it does not mean that the LM power is already connected to the command module power, for the low position of the switch is not currently connected to the command module power.
The switches I have circled in red must also be changed to connect the command module power; this is what they call "initiating the command module power to LM".
After the switches have been changed, the LM power is now connected to the command module power.
Conversely "Desactivating command module power to LM" means acting on the switches I have circled in red.
Now they have been changed so that the command module power no long comes to the switch circled in red.
"command module initiating LM power on" means changing this switch position.
After the switch has been changed position, the LM power has been transferred to its internal power.
But it was not necessary to complicate so much: the lower end of the switch circled in red could directly permanently be connected to the command module power, so that this switch would just have to be changed position to switch the source of the LM power.
This is the schema of the Deadface relay and staging logic.
The abort stage button energizes electromechanical relays I have circled in red; these electromechanical relays change the switches I have circled in orange and violet.
They say this:
"after the ascent stage battery MFC's have placed the ascent stage batteries on the line, additional abort stage relay contacts supply an on/off reset signal through the RJB, to each descent stage battery and to the deadface relays".
The ascent stage batteries are placed on line by the switches I have circled in orange, and the additional abort stage relay contacts are those I have circled in violet; the problem is that the first switches and the second ones are activated in the same time.
The switches circled in violet are changed simultaneously with those circled in orange, not later like they try to make believe!
If they had wanted to delay the switch of the additional abort stage relay contacts relatively to the activation of the ascent batteries, they should have connected them to electromechanical relays commanded by the delayed action of the abort stage button (which was perfectly possible, but not made in the interface they show).
This is the schema of the Descent stage electrical control assembly.
They say this about this control:
"The MFC's are electrically interlocked to prevent closing an HV contactor when a LV contactor is already closed and vice versa".
Two barred parallel bars, annotated "HV", on the path of the HV set, mean that the HV set command can only be taken into account if HV is not currently set.
Likewise, two barred parallel bars, annotated "LV", on the path of the LV set, mean that the LV set command can only be taken into account if LV is not currently set.
But these controls don't prevent from setting HV on if LV is currently set, or from setting LV on if HV is currently set, which are yet the actual controls which should be made.
Preventing HV from being set if it is already set is not very useful, for, if HV is already set, setting it a second time will not change its state.
This is how the controls should have been done, like I show on this modified schema:
- HV setting should be prevented if LV is currently set (I have changed the annotation from "HV" to "LV").
- LV setting should be prevented if HV is currently set (I have changed the annotation from 'LV" to "HV").
This is the block diagram of an Inverter.
A DC-TO-DC converter provides a regulated signal from 53 to 60 volts.
This signal is converted into an alternating current.
The alternating signal then goes into a voltage regulator which provides a control output which goes into the DC-TO-DC converter, so that the voltage of the alternating current is stabilized at 115 volts AC.
But it is a useless complication, for it is easier to regulate a continuous current than an alternating one (for the alternating current has to be converted to continuous to make the regulation).
In fact the regulator should have directly regulated from the continuous output of the DC-TO-DC converter, so that the output of the latter is directly regulated at 57.5 volts DC (which becomes 115 volts AC after conversion to alternating current), like I show on this modified schema.
They say:
"When EPS batteries are in use, the primary glycol cooling loop (EPS) must be operating. If this restriction is not observed, EPS components will be damaged. The only deviation to this is at low power (200 watts or less); then batteries can operate for 8 hours without cooling."
And after 8 hours they need cooling?
How do they determine this figure?
It must also depend on ambient temperature which can change!
They don't specify at which ambient temperature this estimation is valid.
They say:
"When supplying power, temperature must be maintained between +29° and +100° F.
If this restriction is exceeded, battery would be damaged or voltage output could go out of specification (less than 26.5 volts dc)."
29°->100° in the fahrenheit scale represents -1.6°->37.7° in the Celsius scale.
It's not very tolerant; it seems that your car batteries are able to do better than the batteries of the lunar module!
Now, what allows to control the temperature in the lunar module?
The batteries of course!
If the batteries are not able to maintain the temperature above the low threshold of their normal functioning range, they still will be less able of it after they have lost power because of the temperature going under the low threshold.
So, because they lose power and are less able to maintain the temperature, the temperature is going to drop more; and, because the temperature drops more, the batteries lose more power, and, because the batteries lose more power, the temperature drops more, and, because the temperature drops more, the batteries lose more power, and so on...
It's a vicious circle!
They say:
"Maximum continuous inverted power output must not exceed 350 volt-amperes. Demand can go to 525 volt-amperes for up to 10 minutes. If this limitation is exceeded, inverter components could be damaged."
If the maximum power output cannot continuously exceed 350 volt-amperes, it means that an excess of power beyond this limitation would quickly cause damage.
525 volt-amperes is much beyond this limitation, so it is obvious that it would quickly be damageable, much quicker than in 10 minutes!
They say:
"Maximum command module power to LM during docked coast phases is approximately 296 watts peak (average is approximately 108 watts). If this restriction is exceeded, circuit breakers in the command module will trip, shutting off power to the LM.
Oh really?
This is rather brutal!
Why not simply limit the power to this restriction rather than outright shutting off the power if it is exceeded?
They say:
"Available ascent electrical energy is 17.8 kilowatt-hours at maximum steady-state current drain of 50 amperes per battery, at 28 volts dc."
And this:
"Available descent electrical energy is 58.6 kilowatt-hours maximum at steady-state current drain of 25 amperes per battery, at 28 volts dc."
The individual power of an ascent battery is equal to 17.8/2=8.9 kilowatt-hours, while the individual power of a descent battery is equal to 58.6/5=11.72 kilowatt-hours.
Now, the powers are not given at the same current drain; the indicated power for the ascent batteries corresponds to a current double of the descent batteries.
The greater the current the battery works on, and the shorter it will last, and conversely the smaller the current the battery works on, and the longer it will last.
For an ideal battery, it will last twice shorter for a double current; its power would be expressed as: P=I*T, I being the discharge current, and T the time of discharge.
However, a German engineer, Punkert, has shown that the power of the battery was in fact expressed by the formula: P=T*I^k, k being the Punkert constant (^ is the symbol for the power operator); the higher the Punkert constant, and the faster the battery will discharge if the intensity of the discharge current is increased.
For normal quality batteries, this constant is between 1 and 1.2.
However, for cheaper batteries, this constant can go over 1.2.
The power of the ascent battery being expressed for a double current of the descent batteries, if the ascent batteries and descent batteries are identical, their Punkert constant is then such that: 0.5^(k-1)=8.9/11.72 (8.9 being the power of the ascent battery, and 11.9 the one of the descent battery for a current half of the ascent battery).
Solving this equation gives: k=1.4.
But 1.4 does not correspond to a quality battery, like we could have expected NASA to use them on the lunar module, but to a cheap battery instead.
So, either the ascent batteries are less powerful than the descent batteries, or both are cheap quality batteries!
And using low quality batteries for the ascent is not really a wise choice, especially when, moreover their normal guidance work...
...They also have to power the RCS which constantly has to correct the torque created by the disalignment of the line of thrust with the center of gravity because of the aberrant misplacement of an ascent fuel tank...
...And they also have to power the maneuver making the LM dock to the command module.
They say:
"During descent engine burns, the corresponding descent and ascent stage batteries (by supplied bus) must be paralleled to preclude a low bus voltage due to descent battery failure."
That's true, paralleling descent batteries with ascent batteries will insure that there will be no bus voltage drop in the descent (unless the ascent batteries also fail); but, if the descent batteries are not reliable enough to guarantee the safety of the descent and need the ascent batteries for that purpose, it means that the same problem also exists on the ascent.
Yet, on the ascent, there will be no batteries to be paralleled with the ascent batteries to guarantee that there will be no bus voltage drop, and the ascent batteries will have been partially discharged in the descent by this paralleling.
It means that, in order to make the descent safer, they make the ascent still more unsafe...
...Whereas the ascent batteries still have more work to do, for they must also insure that the RCS constantly corrects the torque created by the disalignment of the line of thrust with the center of gravity, a problem which does not exist in the descent!
Absurdity at its summum!
They say:
"Both EPS: CROSS TIE circuit breakers on panel 16 must be opened during descent engine burns. If this restriction is not observed, a short on one bus will affect the other bus."
Opening one circuit breaker is enough to prevent a short on one bus to affect the other one.
They say:
"The EPS: CROSS TIE BAL LOADS circuit breaker on panel 11 must be closed at all times: If this restriction is not observed, redundant power to the Instrumentation Subsystem and EPS displays will not be available."
If it must be closed at all times, why not simply replace it by a direct connection rather than a circuit breaker?
They say:
"Maximum current drain on one ascent battery during ascent engine burns (abort condition) is 104 amperes. At higher current drains, the d-c bus voltage may drop below the low operating limit.
Let's take a battery which outputs a voltage of 28V at a maximal current of 50A.
It means that if the current drain remains under 50A, the voltage between the ends of the battery will remain at 28V.
The system connected to the battery will work correctly if the voltage remains over 26V, but will stop functioning if the battery's voltage drops under 26V.
Now, the system connected to the battery demands a current of 55A from it.
This current is over the maximal current the battery can produce at its nominal voltage, and this excessive current makes the battery's voltage drop to 25.99volts.
The current battery's voltage is under the operating limit of the system connected to the battery, and does not allow it to work.
So it stops draining current from the battery.
Because the system connected to the battery drains no more current from the battery, for having become inoperational, the battery's voltage comes back to its nominal state, a state which allows the system connected to the battery to work again.
So, if the system connected to the battery tries to drain from it a current which makes the battery's voltage drop under its operating limit, the battery's voltage is not going to remain under this operating limit in a persistent way, but is going to alternate between its nominal voltage and the operating limit of the system.
The d-c bus will not really drop below the low operating limit, for, as soon as it reaches it, it immediately goes back up.
What is sure is that the system connected to the battery is not going to work correctly if it tries to drain a current which would make the battery voltage drop under its operating limit.
They say:
"Inverter output voltage must never drop below 110 volts ac; otherwise, the descent engine control assembly (DECA) may become inoperative."
The DECA should not become inoperative if the Inverter output voltage drops under 110 volts.
If that was the case, it would mean that it is more than unsafe.
(but don't worry for them; remember: They are on the fake moonset!).
