...10,000kg payload to 32.5deg 250km by 220km orbit with second stage burn to depletion.MECO at t+145s, 1.5km/s.First stage boostback to LZ-1, with only 99km apogee...Seems like a pretty nice time for the first stage. Are there any obvious issues with it though?
Seems like a pretty nice time for the first stage. Are there any obvious issues with it though?
Quote from: Flying Beaver on 04/12/2017 09:43 pmhttps://www.flightclub.io/results/?id=0d9a43bc-328a-481d-9cbc-22321c3f95d3&code=NONEIf you visit the link posted, you'll see there's a graph of throttle settings over time. The MaxQ throttle looks like 70% from T+50 to T+75. Bit extreme, I reckon, but probably explains the dV deficiency.Quote from: Flying Beaver on 04/12/2017 09:43 pmSeems like a pretty nice time for the first stage. Are there any obvious issues with it though?The main problem I have is that your landing burn lasts for almost 90s. The retropropulsion through the entire lower atmosphere is the reason why the aerodynamic pressure on descent is so low, but this is extremely inefficient! Also the landing burn is at about 50% throttle the entire time which is also very inefficient. Best to do as short a landing burn as possible to minimize gravity losses - so you wanna maximise aerobraking and burn at a high throttle setting when you do start the burn. Kudos getting to orbit on the first attempt though, that's pretty impressive
But it is still 10tons to LEO, with RTLS, no matter how inefficient the landing burn. Would the reason for SpaceX not using a profile like this be about having a buffer for second stage performance?
A preliminary S1 profile for NROL-76. Thrust still appears to be 90% of rated, so perhaps not Block 4.
I already did analysis here and here, if you want to compare and contrast.
Interesting. Did you subtract the acceleration caused by gravity? Also, what is the jump in velocity near 245s and 337s?
Quote from: Welsh Dragon on 05/02/2017 12:19 pmI already did analysis here and here, if you want to compare and contrast.Thanks, I should explain what I've done, perhaps it's slightly different. <snip>
Mine are just straight plots from the telemetry.
I literally sit there and copy the numbers off manually. Every 5 seconds for the whole flight, every second for the burns.