(Delta 7925 is for some reason much more efficient at 8814 m/s). The end up with total delta-V requirement very similar to what Falcon provides: Ariane-4 9138 m/s, Atlas-1 9243 m/s, Space Shuttle 9230 m/s, Saturn V 9267 m/s, Titan Centaur 9207 m/s. This is done for many vehicles in this lecture, which quotes "Space Propulsion Analysis and Design", by Humble, Henry and Larson. From the total delta-V you need to subtract drag and gravity losses, and add the benefit of Earth rotation, and still end up with an orbital velocity of 7800 m/s. Assuming the fairing jettisons at stage separation (not quite true), the second stage starts at 138.8t and ends at 27.3t. At launch the rocket masses 606.8t, at burnout 171.8t. Now assume the first stage average ISP is 300 (between SL and vacuum), and the empty mass 29t (to include residuals). Second stage ISP is 348, from the SpaceX web site. If we assume 4t for the fairing, 4.5t for the empty mass (this will be shown to be consistent later), a typical 5t GTO payload, then the fuel is 111.5t. For the second stage, Elon Musk said the first stage is pushing 125 tonnes. This is pre-densification (and has the pre-stretch second stage) so let's add 6% to get 435,000 kg. The FAA report from 2014 says the first stage holds 411,000 kg. First, fuel amounts and other empty masses. Here are the back of the envelope calculations to back this up. Quote I can't speak for Ed, but the numbers look very plausible to me for the SpaceX claimed capacities of 22.8t to LEO and 8.3t to GTO. (Edit: envy887 says the calculator link above has been posted here elsewhere before. If there was some way to aggregate his posts and summarize them here, that would be useful. I'll also mention LouScheffer who has done excellent work estimating F9 performance on various recovery missions and the marginal differences in propellant usage based on payload mass and trajectory differences between missions. But if the creator of the calculator keeps updating it with actual mission data, it should improve with time. On a typical supersync GTO mission with ocean recovery of stage 1, the 95% confidence level for payload mass gives a range of about 1500 kg, so there's still a good bit of uncertainty. I've just started experimenting with it and don't know how accurate it is, but it seems to be in the right ballpark. To kick off the thread, envy887 just brought this Falcon 9 performance calculator to our attention: Note that it can calculate max payload to orbit with or without stage 1 recovery. I thought the subject deserved its own thread. The ship returned to the Port of Los Angeles late Monday.We've had lots of performance calculations scattered about in mission threads, but no central place to collect and discuss them. For the final landing burn, only the center engine fires to slow the rocket’s descent. Identifiable debris aboard the landing ship includes the Falcon 9 rocket’s engine section, which has nine Merlin 1D powerplants arranged in an “octaweb” configuration. The Falcon 9’s second stage continued into orbit with the Jason 3 satellite, successfully delivering the new ocean observatory to orbit more than 800 miles (1,300 kilometers) above Earth to begin a five-year mission measuring ocean waves and sea level rise. The vessel was positioned in the Pacific Ocean nearly 200 miles south of Vandenberg for Sunday’s landing attempt. SpaceX intended to recover the 14-story booster on the company’s landing barge - named “Just Read the Instructions” - in an experimental secondary objective following Sunday’s launch of the U.S.-European Jason 3 ocean observatory from Vandenberg Air Force Base in California.īut one of the four landing legs at the base of the rocket failed to lock, and the landing gear crumpled after an otherwise smooth touchdown, causing the booster to tip over and break apart in a fireball, throwing wreckage across the football field-sized ship. Debris from SpaceX’s Falcon 9 rocket booster returned to shore in Southern California late Monday after it tipped over on touchdown on a landing platform in the Pacific Ocean following liftoff with a ocean study satellite.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |