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Post by Jairo on Nov 7, 2007 10:33:44 GMT -4
If they were running out of time and willing to take the risk, would it be possible to land and return with the LM of Apollo 10?
Besides experience, does it lacked anything necessary for a landing?
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Bob B.
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Post by Bob B. on Nov 7, 2007 11:12:24 GMT -4
I know the Apollo 10 LM weighed considerably less than the others, so clearly there was something different about it. I don't know, however, exactly what the differences were or whether it was capable of a landing.
Apollo 10 LM: 30,735 lbm
Apollo 11-14 LMs: 33,278 to 33,685 lbm
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Post by Czero 101 on Nov 7, 2007 12:39:59 GMT -4
Quoting from the Apollo 10 Press Kit: Also from the A10 press kit: From the Apollo 11 Press Kit, part 2: Apollo 11 ascent stage was 23 pounds heavier, descent stage was 220 pounds lighter, carried 8 pounds less RCS propellant, 34 pounds less DPS propellant, but carried 2,595 pounds more APS propellant, for a total weight difference of 2,356 pounds. Somewhere in there must also be that A10's LM did not carry any of the Lunar Surface Experiment packages, and I would assume that A10 also did not carry the astronaut's EVA suits or the PLSS backpacks. |
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Bob B.
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Post by Bob B. on Nov 7, 2007 13:07:54 GMT -4
That's not enough propellant to reach orbit. The APS had a specific impulse of 311 s, so the delta-v using the above numbers is,
delta-v = 311*9.80665*LN((4781+2619)/4781) = 1,332 m/s
That won't get it done. It looks like Snoopy may have been able to land but it doesn't look like it could have gotten back to Charlie Brown.
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Post by Czero 101 on Nov 7, 2007 13:28:44 GMT -4
That's not enough propellant to reach orbit. The APS had a specific impulse of 311 s, so the delta-v using the above numbers is, delta-v = 311*9.80665*LN((4781+2619)/4781) = 1,332 m/s That won't get it done. It looks like Snoopy may have been able to land but it doesn't look like it could have gotten back to Charlie Brown. Which seems to make sense considering it was never intended to land on the lunar surface, and also when looking at the propellant loadouts for subsequent missions. A11 through A17 had APS propellant loads averaging around 5,300 lbs. Also, A11 through A14 Decent stage dry weight averaged around 4,700 lbs., A15 through 17 averaged around 6,100 lbs due to the redesign to accommodate longer duration J missions. They also carried approximately 1,000 lbs. more DPS propellant. Ascent stage dry weights throughout all missions remained relatively constant averaging around 4,700 lbs. Cz |
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Bob B.
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Post by Bob B. on Nov 7, 2007 14:36:55 GMT -4
If they were running out of time and willing to take the risk, would it be possible to land and return with the LM of Apollo 10? Based on the given propellant load, apparently not. If a problem occurred during decent that required an abort, the ascent stage would have separated from the decent stage, fired its engine, and returned to orbit. I don’t know all the details of Apollo 10, but it appears they essentially practiced an abort scenario by jettisoning the descent stage and returning to the CM without landing. On the later missions the LM ascent stage needed enough propellant to reach orbit all the way from the lunar surface, which also gave the LM enough propellant for all the abort scenarios. Apollo 10 needed only enough propellant for the abort plus a margin. This is apparently what was done based on the mass figures provided by Czero 101. They had enough propellant to safely return to the CM in abort mode but not enough to allow a launch from the surface. |
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Post by PhantomWolf on Nov 7, 2007 16:16:59 GMT -4
Under the mission as was? Landing, yes, they could have. Getting back off, no they couldn't.
I guess that if NASA had really thought that the Soviets were about to land they could have fueled Snoopy's Ascent Module up to the required amount and used it for a landing though.
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Post by PhantomWolf on Nov 7, 2007 16:20:56 GMT -4
I don’t know all the details of Apollo 10, but it appears they essentially practiced an abort scenario by jettisoning the descent stage and returning to the CM without landing. That is exactly what they did. They took Snoopy down to the 50,000 feet mark, the point where the final Go/No Go is given before entering the landing program, then aborted the landing with the stages separating, a test of the abort systems as well as for LOR. |
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Bob B.
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Post by Bob B. on Nov 7, 2007 16:47:55 GMT -4
That is exactly what they did. They took Snoopy down to the 50,000 feet mark, the point where the final Go/No Go is given before entering the landing program, then aborted the landing with the stages separating, a test of the abort systems as well as for LOR. Thank, PW. I knew the general details of Apollo 10 but I wasn't certain the flight plan included the test of an actual abort scenario, though I assumed it did. It would seem a lost opportunity not to. |
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Post by Hypersonic on Nov 7, 2007 17:37:42 GMT -4
Michael Collins mentioned LM-4 being overweight in Carrying the Fire. IIRC, he said if it had been up to him he would have given Apollo 10's crew another month of training, 11's LM, and let them land.
I think the Grumman weight-reduction programs (WIP & SWIP) were incremental, and LM-4 missed the last round necessary for landing.
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Post by PhantomWolf on Nov 7, 2007 18:41:56 GMT -4
Michael Collins mentioned LM-4 being overweight in Carrying the Fire. IIRC, he said if it had been up to him he would have given Apollo 10's crew another month of training, 11's LM, and let them land. I think the Grumman weight-reduction programs (WIP & SWIP) were incremental, and LM-4 missed the last round necessary for landing. I don't know if this is actually correct. According to Apollo by the Numbers the Apollo 10 LM was 30,735lb whereas Apollo 11 was 33,278lb, that means that at launch Apollo 11 was 2,543lb heavier than Apollo 10. When you check their fuel/Oxidiser, Apollo 10 had a combined total of 18,218.7 in the Descent Module and 2,631lb in the Ascent Module, whereas Apollo 11 had 18,184lb in the Descent and 5,238lb in the Ascent, a combined difference of 2572.3lbs. That means that Snoopy was only 29.3lb heavier than Eagle. |
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Post by Czero 101 on Nov 7, 2007 21:02:04 GMT -4
I don't know if this is actually correct. According to Apollo by the Numbers the Apollo 10 LM was 30,735lb whereas Apollo 11 was 33,278lb, that means that at launch Apollo 11 was 2,543lb heavier than Apollo 10. When you check their fuel/Oxidiser, Apollo 10 had a combined total of 18,218.7 in the Descent Module and 2,631lb in the Ascent Module, whereas Apollo 11 had 18,184lb in the Descent and 5,238lb in the Ascent, a combined difference of 2572.3lbs. That means that Snoopy was only 29.3lb heavier than Eagle. I was having a hard time following your math the way it was laid out in your post so I looked at it this way: Snoopy launch weight: 30,735 DPS Propellant loaded: 18,218.7 APS Propellant loaded:2,631 Snoopy "dry" weight: 9885.3 Eagle launch weight: 33,278 DPS Propellant loaded:18,184 APS Propellant loaded:5,238 Eagle "dry" weight: 9856.3 Eagle is lighter than Snoopy by about 29 lbs. When I use numbers found in the Apollo 10 and 11 Mission reports (respective section / page numbers provided), I get this: Snoopy weight at launch: 30,735 lbs. (Appendix A.4 "Mass Properties: Table A-4-1", pg. A-10)DPS Propellant loaded: 18218.7 lbs. (8.13.1 "Consumables: DPS Propellant", pg. 8-41)APS Propellant loaded: 2631 lbs. (8.13.2 "Consumables: APS Propellant", pg. 8-41)RCS Propellant loaded: 634 lbs. (8.13.3 "Consumables: RCS Propellant", pg. 8-42)O 2 loaded, both stages: 52.2 lbs. (8.13.4 "Consumables: Oxygen", pg. 8-43)H 2O loaded, both stages: 403.7 lbs. (8.13.5 "Consumables: Water", pg. 8-43)Snoopy "dry" weight: 8795.4 lbs. Eagle weight at launch: 33,297.2 lbs. (Appendix A.6 "Mass Properties: Table A-1", pg. A-11)DPS Propellant loaded: 18,184 lbs. (9.13.1 "Consumables: DPS Propellant", pg. 9-32)APS Propellant loaded: 5,238 lbs. (9.13.2 "Consumables: APS Propellant", pg. 9-32)RCS Propellant loaded: 634 lbs. (9.13.3 "Consumables: RCS Propellant", pg. 9-33)O 2 loaded, both stages: 53.2 lbs. (9.13.4 "Consumables: Oxygen", pg. 9-34)H 2O loaded, both stages: 302.3 lbs. (9.13.5 "Consumables: Water", pg. 9-35)(* A11 Mission Report give figures for Helium loadout, but the A10 Mission Report does not, so it has not been figured into the above calculations. Helium loadout for A11 was 61.3 lbs. total for both stages. It can be reasonably assumed that the A10 Helium loadout would be of comparable weight, with a negligible margin for error.) Eagle "dry" weight: 8885.7 lbs. Based on these numbers alone, the Eagle was heavier by 90.3 lbs. However, there are some factors that are not taken into account, such as the weight of the PLSS packs, the MESA pallet and EASEP experiments which I estimate to have a total weight of about 600 pounds. If we take that into account we can figure that the difference in weight between the two vehicles would be about 500 lbs in favour of the Eagle. Cz |
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Post by PhantomWolf on Nov 7, 2007 23:53:33 GMT -4
If we take that into account we can figure that the difference in weight between the two vehicles would be about 500 lbs in favour of the Eagle.
That's assuming those things were actually including in the weights given and it wasn't just the pure spacecraft weights and not the lugage as well.
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Post by Hypersonic on Nov 8, 2007 13:34:05 GMT -4
To further confuse the issue, here are the dry weights of the stages dry from Apollo by the Numbers
10 11
Ascent stage weight, dry, lb 4,781 4,804
Descent stage weight, dry, lb 4,703 4,483
Total weight, dry 9,484 9,287
By that Eagle was lighter. But that doesn't seem to correspond with the numbers PW pulled about the same vehicles from the same source. Except that the difference between PW calculated between the total weights, 2572.3lbs, is very close to the difference between the total weights given, 30,735lbs and 33,278lbs.
To further muddy the waters, I added the dry weights to propellant and consumables, totaling 31,484.9 and 33759.8.
My guess is Eagle was lighter, but was loaded with more fuel and luggage.
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Post by Czero 101 on Nov 8, 2007 14:35:03 GMT -4
To further confuse the issue, here are the dry weights of the stages dry from Apollo by the Numbers 10 11 Ascent stage weight, dry, lb 4,781 4,804 Descent stage weight, dry, lb 4,703 4,483 Total weight, dry 9,484 9,287 By that Eagle was lighter. But that doesn't seem to correspond with the numbers PW pulled about the same vehicles from the same source. Except that the difference between PW calculated between the total weights, 2572.3lbs, is very close to the difference between the total weights given, 30,735lbs and 33,278lbs. To further muddy the waters, I added the dry weights to propellant and consumables, totaling 31,484.9 and 33759.8. My guess is Eagle was lighter, but was loaded with more fuel and luggage. The numbers you've found are the same numbers that I originally found in the Apollo 10 & 11 press kits. These were distributed typically a week or two before launch, and gave the proposed weights and loadouts, which seem generally to be slightly different from the actualy flight loadouts. The second set of numbers I used came from the A10 & 11 Mission Reports, compiled after the mission had returned, and using as much as possible accurate weights and lodouts. Of course there is always some margin for error, but, IMO, I would think that the Mission Reports would have more reliable information. Having said that, I've looked through many many different documents and onlie resources in the last little while and it seems that every one has a different figure for the LM weights. ALSJ has "as flown CM / LM stowage lists" for A12 to 17 that have weights for pretty much everything onboard, but so far I haven't been able to find a similar set of documents for any of the earlier Apollo flights. Cz |
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