Race to Proxima Centauri

[A Fat Pokemon]

I made 21658.4 M/S without a sun dive, just a straight out burn.

[zarakon]

(0.13 sun dive)

[MeticulousMitch]

Congratulations to new challenge leader Max Schram! Very efficient rocket by the looks of things, and I especially like the detachable fuel tanks.

Won't be long now before I'm booted off the leaderboard...

most of my rocket was destroyed because of a mecjeb warp error but heres the pic.[ATTACH=CONFIG]34834[/ATTACH]

Fried, I'm having trouble reading the speed on your picture. It looks like 73,101.x m/s, but I can't read the number after the decimal point. Can you confirm for me what the full number is?

Also, mechjeb aside, I assume this is using modded parts judging by that odd-looking capsule. Again, hard to tell from the low-quality screenshot.

@Zarakon: You should try this challenge in 0.17 - sundiving is a lot of fun with the new sun model.

[SunJumper]

I would assume the number to be zero...

[Fried]

I can confirm and it was with mods but no sundive i will post a hire rezz photo of the speed soon but it is lees than it was in that pic by a few m/s because of deseleration.

[Max Schram]

Since i have not much to do at work atm, i did some simulation on this topic. I want to share some of the results with you guys to improve our final velocites.

First some considerations:

I thought about the Sundive and its effect on the final result and came to the following conclusion: Gravity is acceleration in direction of the governing body (The Sun) and decreases velocity over time. To minimize its influence it's necessary to increase the distance as quick as possible, because the amount of deceleration decreases with distance. In order to achieve a maximal velocity we not only want to generate as much deltaV as possible, we also want to apply it as fast as possible.

A low periapsis and high apoapsis support this fact, because this setting ensures a maximum velocity for the closest (to the sun) part of the trajectory. Since a bi-elliptic transfer is the most efficient way to reach the sun, this is what we are looking for. Initiating a burn near periapsis also increases this effect. I did an ODE solve for the Movement Equation around the sun and generated some pictures to illustrate the previous thoughts.

The first two pictures show the effect of the apoapsis altitude on the final velocity. The effect grows with altitude, but doesn't increase to much after 200e9 m. Going even higher mostly increases flight time to a couple of years, which would take hours even on full time warp.

I measured the final velocity at 9e10m to cut down simulation time. But a faster vessel (without additional deltaV applied after this point) will also be faster at 100e10m.

The next pictures illustrate the impact of the periapsis altitude. As expected, the final velocity is decreasing with higher periapsis. The main reason for this chart was my own consideration while doing this challenge: Burning before periapsis, increased it about some 100km and i was worried it could have an impact on the result. But 100km is relatively small compared to the altitude increments in this test and can be ignored safely.

The last test is the most interesting and covers some effects of the burn point and the applied deltaV. The first picture illustrates the varying burn interval relative to the periapsis. The x-axis in the second picture corresponds to the burn start time before the periapsis, relative to the full burn length. E.g. -1 corresponds to the left trajectory of the first picture and 0 to the most right trajectory.

The five curves show different vessels with an increasing amount of Rockomax X200-16 Fuel Tanks. The rest is: Command Pod Mk1 and LV-N Atomic Rocket Engine. As one can see, the best point to burn is between 60% - 70% of the burn time before peripasis. This might vari for other crafts, with more thrust or better staging. Adding deltaV (more tanks) does help, but only to a point were the final velocity can't be increased.

[Fried]

Im lost english please at what altitude should i strive for and where do i burn?

[Max Schram]

Go for a Sun apoapsis above 100,000,000km (the more the better) and a Sun periapsis below 100km (the lower the better). Then calculate the remaining burntime of your vessel (time = Fuel/FuelPerSecond) and take 50%-70% of it. Start burning at this amount of time before periapsis in prograde direction until you run out of fuel.

[skippy]

80.379 years missed the mark by a little and yes definitely with mods also how do i upload the screenshot

speed 16211202.6 m/s

distance 1159 Gm

[SmallChange]

Please mind the post dates