Buzzard Collectors

[iontom]

 

On 12/27/2017 at 6:23 AM, FreeThinker said:

@DStaal

Alright, I have calibrated KSPIE Bussard Ramjet drag to a top speed of 0.12c You can go faster by disabling the ramjet. Ideally, you combine it with a  beam core antimatter reactor with magnetic nozzle to accelerate to 0.67c, coast to the destination and then use the magnetic scoop to drag down to 0.01c

I finally had time to test this yesterday. Been a busy few months, plus I had to figure out some issues that Kopernicus and CommNet were causing for me.

I loved the new Anti-Hydrogen tanks. I'll try to think more about those too. I could ONLY  reach about 0.15c, but I still was playing around w/ antimatter to matter to dry mass ratios. I mostly just threw things together to test. I'd love to see your craft designs for those!

In regards to reviewing the braking force, I'll review some eqns tomorrow. The braking range sounds about right though. I wasn't able to find if you had a special tank designed to capture interstellar medium. It is mostly molecular and atomic hydrogen though, but you'd still need some mechanisms to cool and prepare it. There's some helium and dust. https://en.wikipedia.org/wiki/Interstellar_medium

The harder part will be determining deceleration to mass inflow rate - so how quickly you brake vs how much ISM/hydrogen you can fill into your tanks. I think you must have this modelled a little bit already but it seems to be mostly with your special bussard engine? Theoretically you could use that hydrogen w/ any engine, but would it really be enough is the question.

Also - it'd be exciting to apply a similar force mechanic to a photon sail. You've got a lot of the pieces in place for it to work. I also saw this today - looks like they might be modelling project Starshot or trying to.

Keep up the awesome work!

[FreeThinker]

8 hours ago, iontom said:

I loved the new Anti-Hydrogen tanks. I'll try to think more about those too. I could ONLY  reach about 0.15c, but I still was playing around w/ antimatter to matter to dry mass ratios. I mostly just threw things together to test. I'd love to see your craft designs for those!

 

Yep, you got that right! As you know Antimatter is extremely hard to store at high mass ratios. The achieve the best mass ratios we need to store it as a big frozen ball contained magnetically in a near zero-g environment  in deep space (far away from the sun or other heat). The key is maximizing the mass ratios for the final interstellar trip in interstellar space.  The trick to achieve it is to use 2 stages where the first stage consists of high resistant Antimatter tank which serves as a temporary transfer storage stage of antimatter while being in the solar system until drifting into interstellar medium after which you transfer all antimatter to the interstellar tanks with much better mass ratios before going full throttle on the interstellar antimatter engines. According to my calculations, a mass ratio of e (= 2.718) should be possible, allowing the interstellar vessel to achieve 0.67c. Possibly using multiple stages or drop tanks this could be increased much higher. Perhaps we should make a change of it, trying to go as fast as possible.

Edited February 21, 2018 by FreeThinker

[iontom]

7 hours ago, FreeThinker said:

Yep, you got that right! As you know Antimatter is extremely hard to store at high mass ratios. The achieve the best mass ratios we need to store it as a big frozen ball contained magnetically in a near zero-g environment  in deep space (far away from the sun or other heat). The key is maximizing the mass ratios for the final interstellar trip in interstellar space.  The trick to achieve it is to use 2 stages where the first stage consists of high resistant Antimatter tank which serves as a temporary transfer storage stage of antimatter while being in the solar system until drifting into interstellar medium after which you transfer all antimatter to the interstellar tanks with much better mass ratios before going full throttle on the interstellar antimatter engines. According to my calculations, a mass ratio of e (= 2.718) should be possible, allowing the interstellar vessel to achieve 0.67c. Possibly using multiple stages or drop tanks this could be increased much higher. Perhaps we should make a change of it, trying to go as fast as possible.

Yeah, I think there's a few mass ratios here. To start with, here are the ones that directly are measured when building a ship in the VAB:

M_{H_reaction}/M_AH

(M_{H_reaction} + M_AH + M_{H_ReactionMass})/M_{Dry_Ship_Mass}

Now, I guess it turns out the actual ratios are much more complicated. Firstly, some of the hydrogen you're carrying doesn't react, it just gets superheated an ejected at relativistic speeds. There is a ratio of hydrogen/antihydrogen that gives you the amount used for fuel and the amount that just gets blasted out at relativistic speeds.

Then you add stuff like relativistic mass, and it gets WAY crazier:

I think here's the same EQN from wikipedia:

This looks scare but might not be super hard to calculate since its just numeric, plug and go. It just changes with your speed so your TimeWarp mod may have issues.

Quote

 

"We thus have the surprising result that, even with its extraordinarily high Isp, the antimatter rocket is limited to a ∆V per stage of around 0.25c."

Source

 

 

Then Page 14 and 15 have some a breakdown of nominal mass ratios. And Jesus it's complicated. Depending on your acceleration profile, your trip time can be halved, but your fuel mass cost goes up by factors of 10 or more.

Now, this source is for a purely antimatter driven ship. Using a magnetic sail for braking probably cuts down the nominal wet mass by a lot. Probably more than half depending on how much hydrogen you acquire from your magscoop. You probably could also accelerate with a magsail out of a solar system if you had an ionized beam source propelling it. Or even a microwave laser would probably reflect off the sail if you set it up correctly. I wonder if you could have trapped ions in a much larger sail shape than the wire mesh... Def needs more research. It might be worth putting our questions together and emailing Robert Frisbee. 

Then there's the issue of scaling - hitting such massive velocities looks like it may require gigantic ships. The only viable option I've seen for this is Part Welding and changing TweakScale to allow massive ships, like that guy who made the Star Wars Destroyers. Using tools like that would need to scale correctly with the IE Mod's reactors, engines and timewarp acceleration.

Navigation in these missions is really hard in KSP already too (or was when I tried it on Monday). At least, knowing when to start decelerating or using your magsail is really hard to do by yourself. An interstellar co-pilot / planner tool would really help. So many challenges! 

Cheers