It was also likely one of the riskiest spacecraft ever flown by men -- margins were pared down so fine that many of the mission phases (especially lunar lift-off) had single-point-failure scenarios that could result in LOCV.
Every time I saw lift-off footage I was puzzled where those exhaust gazes escape to? I checked your references again and I don’t see enough space between ascending and descending modules, and top of descending module looks flat (with descending engine below). Do you know if it used some sort of solid fuel engines for the first few seconds of lift-off?
The ascent engine intruded into the crew cabin so that the nozzle was flush with the top of descent stage. The propellants of the ascent stage burn with a translucent flame.
As far as I understand RCS were used only for orientation.
I don't have any issues with flame color. I'm trying to understand where those gazes escape. I’m not rocket scientist but it seems to me that ascending engine should explode if nozzle was flush with the top of descent stage.
Was there ever a serious thought to testing just the ascent stage of the LM? Given its loaded weight of 10,000 lb, a partially fueled ascent stage may have been orbited by a Titan II, and certainly by a Saturn I. I can't think of a technical reason why the ascent stage could not be flown as a separate, early test, and given that the LM was in the critical path for Apollo, and it was plagued by delays, I can't see why this would not have been considered.
http://www.hq.nasa.gov/office/pao/History/SP-4205/ch6-2.htmlLook at the 3rd pic. The hole in the middle is where the descent engine went, but it did not fill the whole volume.
Quote from: Jim on 08/05/2009 06:26 pmhttp://www.hq.nasa.gov/office/pao/History/SP-4205/ch6-2.htmlLook at the 3rd pic. The hole in the middle is where the descent engine went, but it did not fill the whole volume.This sounds like the only possible scenario. I saw some sort of cover on top of descent engine. Did it have a hole in the middle? http://history.nasa.gov/alsj/a11/a11LM5structures.pdf (page 4)I have another, probably stupid, question. Why not to use just one engine? Both engines used same fuel and descent engine was 3x more powerful, so it could lift-off just fine. Plus, they could throttle it. It would save development costs and lunar module mass.
I think one of my favorite aspects is how they combined the 2 fuel and 2 oxidizer tanks into 1 of each and then off set them from the axis of the vehicle by the ratio of lengths vs weights to keep it balanced during the engine burns. A beautiful insight and solution.
Descent engine could get damaged on landing and not be capable of liftoff.
I have another, probably stupid, question. Why not to use just one engine? Both engines used same fuel and descent engine was 3x more powerful, so it could lift-off just fine. Plus, they could throttle it. It would save development costs and lunar module mass.
Quote from: wannamoonbase on 08/05/2009 06:40 pmI think one of my favorite aspects is how they combined the 2 fuel and 2 oxidizer tanks into 1 of each and then off set them from the axis of the vehicle by the ratio of lengths vs weights to keep it balanced during the engine burns. A beautiful insight and solution.1. I'm not sure what you mean. Each stage had its own tanks. http://upload.wikimedia.org/wikipedia/commons/e/e0/LEM-linedrawing.png2. IMHO they put those tanks too far from the center of gravity. 3. As far as I know, those engines use fuel and oxidizer in different proportion so it makes hard to balance the center of gravity. Ascent module had only one fixed engine and very small RCT for corrections.
Quote from: Jorge on 08/05/2009 08:07 pmDescent engine could get damaged on landing and not be capable of liftoff.This wouldn't happen with single engine version because this engine would stay very high in ascent stage. It could break but same could happen with ascent engine in Apollo as well.