Quote from: edkyle99 on 02/06/2018 08:44 pmQuote from: Kabloona on 02/06/2018 08:36 pmQuote from: spacetraveler on 02/06/2018 08:34 pmElon just tweeted that the 2nd burn was to 7000km apogee, a significant raise but much less than GTO.We didn't expect an actual GTO orbit, rather a 20,000 km apogee that would give a 6-hour orbit, with restart at perigee. But obviously not.Elon's five-hours of Van Allen Belt radiation might mean two ~200 x 7,000 km orbits, maybe? I'm trying to figure the period of an elliptical orbit but my mind is buzzing right now. - Ed KyleI'm getting 2 hours, 45 minutes for a 200x7000 km orbit (semi-major axis of 20,000 km). Sound about right?
Quote from: Kabloona on 02/06/2018 08:36 pmQuote from: spacetraveler on 02/06/2018 08:34 pmElon just tweeted that the 2nd burn was to 7000km apogee, a significant raise but much less than GTO.We didn't expect an actual GTO orbit, rather a 20,000 km apogee that would give a 6-hour orbit, with restart at perigee. But obviously not.Elon's five-hours of Van Allen Belt radiation might mean two ~200 x 7,000 km orbits, maybe? I'm trying to figure the period of an elliptical orbit but my mind is buzzing right now. - Ed Kyle
Quote from: spacetraveler on 02/06/2018 08:34 pmElon just tweeted that the 2nd burn was to 7000km apogee, a significant raise but much less than GTO.We didn't expect an actual GTO orbit, rather a 20,000 km apogee that would give a 6-hour orbit, with restart at perigee. But obviously not.
Elon just tweeted that the 2nd burn was to 7000km apogee, a significant raise but much less than GTO.
Two obvious possibilities. 250 x 7000 km is a 2.76 hour orbit. Two of these is 5.5 hours, and this would maximize the Van Allen belt exposure, which Elon was stressing.Less likely, he meant 250 x 17000. That's a 5 hour orbit.In either case, a shorter than 6 hour coast makes sense. If you assume the 6 hour coast was planned for the center of the window, and they launched 1 hour after the center, then you need a 1 hour shorter orbit to get to the canonical injection spot. If they had launched at the opening of the window, it would have taken a 1.25 hour longer coast to get to the right spot.
You can actually spot a part of the center core landing leg going into the drink at 38h:34m into the web cast. I'm quite sure.
Quote from: Nascent Ascent on 02/06/2018 08:10 pmHopefully this question is ok here. Considering that F9H and D4H are about the same size what is the primary reason for the performance differences?Delta IV uses Liquid Hydrogen, which has a density of about 70 kg/m³.Falcon 9 uses RP-1 (Kerosene), with a density of around 800-1000kg/m³.So they can fit around ten times the energy in the same volume.
Hopefully this question is ok here. Considering that F9H and D4H are about the same size what is the primary reason for the performance differences?
QuoteI'm getting 2 hours, 45 minutes for a 200x7000 km orbit (semi-major axis of 20,000 km). Sound about right?You and LouScheffer agree on that (he said 2.76 hrs), so I'll take it you're both right.That means 2 orbits, then burn at/near perigee, assuming Elon's "5 hour" coast quote was a ballpark.
I'm getting 2 hours, 45 minutes for a 200x7000 km orbit (semi-major axis of 20,000 km). Sound about right?
Quote from: envy887 on 02/06/2018 08:50 pmQuote from: edkyle99 on 02/06/2018 08:44 pmQuote from: Kabloona on 02/06/2018 08:36 pmQuote from: spacetraveler on 02/06/2018 08:34 pmElon just tweeted that the 2nd burn was to 7000km apogee, a significant raise but much less than GTO.We didn't expect an actual GTO orbit, rather a 20,000 km apogee that would give a 6-hour orbit, with restart at perigee. But obviously not.Elon's five-hours of Van Allen Belt radiation might mean two ~200 x 7,000 km orbits, maybe? I'm trying to figure the period of an elliptical orbit but my mind is buzzing right now. - Ed KyleI'm getting 2 hours, 45 minutes for a 200x7000 km orbit (semi-major axis of 20,000 km). Sound about right?That's what I got as well. So 5.5 hours from 4:15, or 9:45 east coast time for the last burn, more or less.Quote from: LouScheffer on 02/06/2018 08:46 pmTwo obvious possibilities. 250 x 7000 km is a 2.76 hour orbit. Two of these is 5.5 hours, and this would maximize the Van Allen belt exposure, which Elon was stressing.Less likely, he meant 250 x 17000. That's a 5 hour orbit.In either case, a shorter than 6 hour coast makes sense. If you assume the 6 hour coast was planned for the center of the window, and they launched 1 hour after the center, then you need a 1 hour shorter orbit to get to the canonical injection spot. If they had launched at the opening of the window, it would have taken a 1.25 hour longer coast to get to the right spot.
Is that Earth reflected in the helmet?
Quote from: oiorionsbelt on 02/06/2018 08:54 pmIs that Earth reflected in the helmet?Yes, and in the side of the car!
I get 1230 m/s added for the elliptical orbit injection, meaning another ~3000 m/s remaining for TMI.
I get first apogee coming up pretty soon here, in about a half-hour give or take, assuming a 200 x 7,000 km orbit. - Ed Kyle
Quote from: edkyle99 on 02/06/2018 09:08 pmI get first apogee coming up pretty soon here, in about a half-hour give or take, assuming a 200 x 7,000 km orbit. - Ed KyleThat would be 5:35-5:40 pm or so Eastern.Second apogee around 7:00 pm Eastern, then TMI burn around 9:45 pm.
I wonder if the Guinness Book of Records will take the Tesla's 24,606 mph as the absolute world speed record for cars?
