Recent content by Devin-M

I took some measurements today. The temp was constant 55f. A full preconditioning took 3.3kWh. Then after 2 hours of driving and 61 miles traveled, maintaining the constant preconditioning took a further 1.3kWh. In the pictures below, the preconditioning energy use is shown in miles. These miles...

This graph supposedly shows 30F weather, initial 10% state of charge, temperature preconditioned (grey) vs not preconditioned (green: Source: https://insideevs.com/news/699912/supercharging-tesla-winter-preconditioned-vs-cold-battery-test/

PS… It isn’t necessary to fully charge the battery each time. As seen above, with the battery pre-warmed, two separate 15 minute charging sessions with driving in between provides more energy and range than a single 30 minute session. *EDIT: When I initially viewed this chart I thought it...

Problem: You’re an Uber driver with a Tesla Model 3. Today’s low: 30F, high: 65F. You want to reach a USD$ profit target in the least number of hours, but your choices could have added cost. Do you preheat the battery only when you are headed to the charging station (to increase the charging...

Sorry it’s taken me so long. I’m planning to run the numbers with a 5 solar mass black hole and a 1 solar mass black hole - in a conversation I had with Grok, it told me that the 5 solar mass BH could give 0.95c and the solar mass black hole could give 0.99c at a large distance in this scenario...

kinetic energy per Kg?

So in the formula in post 5, is y the lorentz factor, r the distance in meters from the center? Is M the mass of the black hole in kg? What is E? Energy in Joules?

I will try to work this out later when I have a chance, but on the basis of the photon sphere being smaller on small black hole, and therefore light has to orbit in a tighter radius, I would assume space is more curved at the photon sphere of a smaller black hole. It might take me a day or 2 to...

Would you get the same boost at the edge of the photon sphere with any black hole or is this specific to Sag A*?

And this: “ Oberth effect also can be used to understand the behavior of multi-stage rockets: the upper stage can generate much more usable kinetic energy than the total chemical energy of the propellants it carries.[2]”

Hmm, I thought some of the fuel getting more kinetic energy before being used might be helpful, since the wikipedia article for oberth effect says this: “ In terms of the energies involved, the Oberth effect is more effective at higher speeds because at high speed the propellant has significant...

I assume this is treating the burn as an instantaneous impulse. Would extending the burn over time result in higher speed? In this case, during the burn, a portion of the fuel would acquire more kinetic energy before being utilized.

Seems 0.4c final velocity craft with oberth effect would indeed arrive out to the distance of Andromeda Galaxy before the 0.33c direct route craft, despite the extra distance and time spent getting to Sag A* first at 0.1c before the final burn 0.23c burn.

I’m a bit confused. In this section of the wikipedia article on the Oberth effect, it says: “So if a spacecraft is on a parabolic flyby of Jupiter with a periapsis velocity of 50 km/s and performs a 5 km/s burn, it turns out that the final velocity change at great distance is 22.9 km/s, giving...

If it makes the problem more tractable, the thrust could be treated as a semi-instantaneous impulse, such as an explosion, rather than 7 minute sustained burn. I’m mainly concerned with yes / no is 0.95c possible with 0.33c delta v near sag a* by taking advantage of the oberth effect.