EVE Express!

[kahlzun]

In the spirit of the Munar express challenge, as done by the famous Scott Manley

, i thought it was time to expand the scope.

Namely, to look beyond cislunar space to the planets beyond! A true Brachistochrone flight! To Eve!

Effectively, the challenge is thus: In the shortest time possible, travel to the body in question, land safely, plant a flag, and return to Kerbin, again landing safely and planting a second flag. The trick is that "infinite fuel" cheat (alt+f12) is active, meaning the ship can have extreme accelerations.

The idea is to accelerate to about halfway between the two bodies, turn around and decelerate to allow safe landing.

Note that as flags need planting, kerbal/s must be carried on the flight.

Scoring is entirely based around the time taken for the round trip.

Screenshots and/or video is required showing the flag being planted on both Kerbin and Eve, as well as the MET of the recovered ship (F3 screen)

Eve has been chosen because of its proximity, as well as its thick atmosphere which helps slow down the craft (aerobraking).

My attempt will be uploaded shortly.

RULES:

Victory conditions as outlined above. Fastest time to complete all criteria in one 'go' wins.

Stock parts only (with one exception)

No hyperedit/similar 'cheaty' mods.

MECHJEB is allowed and is, in fact highly recommended. The 'Landing Guidance' system can tell you if you will land on ground or water, and keeping in mind you can't plant a flag on water, would be highly useful. Also the TGT+ allows you to accurately target the destination.

EDIT1: This is taking longer than I expected. I guess this will add another element to the challenge: how long you can be patient enough to continue the burn for..

EDIT2: Well, I crashed on return to Kerbin because I tried to land at the KSC and didn't retroburn. The theory is shown to be sound, however.

Video pending.

EDIT3: Apparantly I'm unable to record commentary at the momeny, so my example is delayed..

EDIT4: Uploaded the example video sans intended commentary. Behold!

Edited July 27, 2014 by kahlzun

[Red Iron Crown]

This would be a bit painful to do as we're limited to 4x time acceleration when the engine is burning. I haven't run the numbers but from the hip I think a brachistochrone transfer is likely to take several days of game time, so you're looking at at least a few hours of watching the ship burn while pointing manually.

I would be interested to know how to calculate and pilot a brachistochrone trajectory, maybe one of the rocket scientist types around here can illuminate us.

[kahlzun]

It actually wasn't too bad. With a low TWR of 7, after about 10-15 minutes of burning, i had an eve collision in ~5h30m. I was travelling around 262km/s at the time.

Considering parts in KSP can get up to ~200TWR, I'd expect times in the realm of 10-15 minutes for an Eve landing are possible, especially if you don't bother to retroburn (eve's atmo is thick enough to bleed off speed ridiculously fast.)

Starting a new save puts Eve and Kerbin near each other (~4.8Gm) so it is helpful.

Edited July 26, 2014 by kahlzun

[Red Iron Crown]

That's more of a high-energy Hohmann transfer than a brachistochrone transfer. Though your results are encouraging, look like my guesstimate was several orders of magnitude off. Should be able to do it in a about an hour or less of burning. Do you do the transfer at 0 phase angle?

[EdFred]

OKTO2 + command chair + inline stabilizer + Oscar B tank + KR-2L + massless solar panels = winner.

Kerbin TWR of over 38. Interplanetary TWR of over 45000.

Currently travelling at 1382855.4m/s - I hope I can stop. Even going through the core of Eve my encounter only lasts 3 minutes. We will see how thick Eve's atmo really is.

Well, that didn't turn out so well. Peaked at almost 1800km/s. My Eve escape was the same time as my encounter. I waited too long to do my retro burn. The KR-2L was destroyed on impact along with the reaction wheel, Jeb, and the chair. Oddly enough, the Oscar B, probe core and solar panels survived. I bounced off Eve, and am now traveling at 2083692.6m/s directly back at Kerbin.

Edited July 26, 2014 by EdFred

[kahlzun]

That's more of a high-energy Hohmann transfer than a brachistochrone transfer. Though your results are encouraging, look like my guesstimate was several orders of magnitude off. Should be able to do it in a about an hour or less of burning. Do you do the transfer at 0 phase angle?

If you had the patience to do it 'properly', with a high-TWR engine and ludicrious speed , then a brachistochrone would probably be the fastest way, sooner or later even Eve's legendary atmosphere would lose the ability to slow you down enough.

Its braking ability is quite shocking though, I went from ~265km/s to 1km/s in the space of about 4 seconds. Poor Jeb must have felt like he hit a wall!

It wasn't quite 0 phase angle, probably closer to 5 or 10 degrees, but like i said before, starting a new save file puts them pretty close together, with Eve practically on the DN of the orbits. That being said, 0 phase angle would probably be the shortest distance, with the added complication that you will have to complete the landing on Eve at night.

Note that when i said a 15 minute burn, i did include the contraction from 4x, it was closer to an hour to Jeb.

OKTO2 + command chair + inline stabilizer + Oscar B tank + KR-2L + massless solar panels = winner....

You have to remember that you need to plant 2 flags for the challenge: one on Eve and one on Kerbin. You don't replenish the flags on the EAS1 chair, so you'd either need to bring 2 kerbals or a pod.

Please tell me if the bounced debris actually hits Kerbin, that would be hilarious!

Edited July 26, 2014 by kahlzun

[kahlzun]

Uploaded example video (Youtube is still chewing on it, give it a few minutes)

This shows my (failed) attempt, and gives some useful tips.

[EdFred]

If you had the patience to do it 'properly', with a high-TWR engine and ludicrious speed , then a brachistochrone would probably be the fastest way, sooner or later even Eve's legendary atmosphere would lose the ability to slow you down enough.

It wasn't quite 0 phase angle, probably closer to 5 or 10 degrees, but like i said before, starting a new save file puts them pretty close together, with Eve practically on the DN of the orbits.

Note that when i said a 15 minute burn, i did include the contraction from 4x, it was closer to an hour to Jeb.

You have to remember that you need to plant 2 flags for the challenge: one on Eve and one on Kerbin. You don't replenish the flags on the EAS1 chair, so you'd either need to bring 2 kerbals or a pod.

Please tell me if the bounced debris actually hits Kerbin, that would be hilarious!

It missed Kerbin, but not by much. it passed between Mun and Kerbin, but was going fast enough it didn't even register that there was an encounter. I went warp 100,000x and did some work around the house, and came back this:

[kahlzun]

Some high-TWR parts, with their weaknesses listed:

[table=width: 500]

[tr]

[td]Name[/td]

[td]Mass[/td]

[td]Thrust[/td]

[td]TWR[/td]

[/tr]

[tr]

[td]Sepratron[/td]

[td]0.0125*[/td]

[td]18[/td]

[td]146.8[/td]

[/tr]

[tr]

[td]LES SRB[/td]

[td]1.0*[/td]

[td]750[/td]

[td]76.45[/td]

[/tr]

[tr]

[td]RT-10 SRB[/td]

[td]0.5*[/td]

[td]250[/td]

[td]51[/td]

[/tr]

[tr]

[td]KR-2L[/td]

[td]6.5[/td]

[td]2500[/td]

[td]39.2[/td]

[/tr]

[tr]

[td]KS-25x4[/td]

[td]9.75[/td]

[td]3600[/td]

[td]33.5[/td]

[/tr]

[tr]

[td]48-7S[/td]

[td]0.2[/td]

[td]30[/td]

[td]30.6[/td]

[/tr]

[/table]

*= SRB weight given in 'depleted' state.

Weakness of SRBs: No thrust gimballing. No throttle. Have to activate/deactivate 'infinite fuel' to control.

Weakness of LES: Non-straight thrust may cause difficulties under high timewarp.

Weakness of KR-2L & KS-25x4: Heavy engines cause difficulties turning, difficult to return Kerbal to pod.

Weakness of 48-7S: Low thrust requires engine cluster to approach theoretical TWR. Sound is annoying.

Edited July 27, 2014 by kahlzun

[kahlzun]

"MET182y" That was some long housework!

Out of curiousity, what was the MET when you hit Eve?

Also, infinite fuel removes the fuel check, you didnt need the oscar-B

Edited July 27, 2014 by kahlzun

[EdFred]

"MET182y" That was some long housework!

Out of curiousity, what was the MET when you hit Eve?

Also, infinite fuel removes the fuel check, you didnt need the oscar-B

The MET was under 2 hours. Closer to 1 than 2 I believe. But I burned towards Eve until about 45 seconds before the encounter. It got big in a hurry. And the inline reaction wheel survived, it also bounced off Eve, and was on a similar trajectory into no where. I know that the fuel tank wasn't needed, but without a fuel tank KER wouldn't give me a TWR.

[MarvinKitFox]

Just some info..

Using a design based around 2*seats, a pile of cubic struts and some seperatrons, I can *get* there in 50m12s, if I assume aerobrake.

Unfortunately, at that time the speed of 3700km/s takes me through EVE's atmosphere, even on a glancing blow, in ONE physics tick.

...Which crashes me to desktop.

(heck, I pass through Gilly's orbit in 12 seconds!!!!!)

With turnaround and slowdown, the way i'm supposed to do, The trip should take about 76 minutes, there and back each..

I still have to figure landing, as the seperatrons only respond to all-off or all-on, thus I have a choice of 0m/s or 1233 m/s of acceleration.

Ew kahlzun! I see your design is only 7.09g of acceleration. No kidding there is room for more vroom!

Seperatrons(empty, plenty of them) top me out at 125.6g

dOH! forgot a picture.

Here in the VAH still. Don't quite believe the TWR, it drops a good bit when 160Kg of Kerbal climbs aboard.

Edited July 27, 2014 by MarvinKitFox