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2 burns, that'all


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this is a simple challenge where your goal is to get to the surface of duna and back in two continuous burns, you can stage, but the throttle slider must stay on until the burn is complete. you can throttle down and adjust your burn a bit, but once you throttle to less then 20% then that burn is complete and hope that it brings you to duna(the less then 20 percent thing is just so that someone can't just set the thrust limiter to 0.5% and get away with all the adjustment in the main burn itself).

once you power down to less then 20% and don't turn it completely off then it is then concidered part of the correction burn(s)

of course that is extremely difficult, so instead the winner will be the person with the lowest amount of delta v used to adjust combined between both burns.

if you don't have a mod that allows you to see delta v then just take the amount of fuel used and divide it by the mass of the vessel after the adjustment burns to get your score (lower is better).

just for the sake of easiness in the math rcs is not allowed, just rotate the craft and use the main engine(s).

no mechjeb or something of the sort.

I tried it but I used at least 400 delta v both ways (and I don't count in the leaderboard).

good luck, more questions just ask.

current ranking leaders.

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Edited by rockets-don't-make-toast
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15 minutes ago, qzgy said:

Can you show your attempt? I would say this challenge is near impossible.

it's really late so I'll do it tomorrow.

I know it's near impossible, that's why I made it so that the person with the least adjustment needed outside of the burn would win.

so the closest to perfect would win.

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6 hours ago, MiffedStarfish said:

So you have to launch, get up to 75000m, then escape and Duna encounter in one burn. Then when you get to Duna you need to capture, deorbit, land, achieve orbit, escape and let in encounter in burn.

<backs away slowly> 

in my attempt I just waited until the duna transfer window, waited until dusk then burned straight up until I was set to escape kerbin and in a trajectory to intercept duna, then I did some adjustments until the intercept was deep in duna's atmosphere, got there, used areobraking to slow myself enough to land then used parachutes to land. Some complications arose and I couldn't do the second burn (tipped over) but I would've done the same thing but from duna to kerbin.

6 hours ago, Physics Student said:

Sounds doable, will try.

 

1 burn to get a close approach with duna

1 mid course correction

 

would it be an exploit to use staging for coasting phases?

 

the object of the challenge is to get as close to to duna as possible in 1 burn, then if necessary some mid course corrections, slow down and land on duna using non powered means, repeat for kerbin. the way you win is to use the least amount of delta v in mid course corrections.

Edited by rockets-don't-make-toast
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On ‎7‎/‎1‎/‎2017 at 7:58 PM, rockets-don't-make-toast said:

this is a simple challenge where your goal is to get to the surface of duna and back in two continuous burns, you can stage, but the throttle slider must stay on until the burn is complete. you can throttle down and adjust your burn a bit, but once you throttle to less then 20% then that burn is complete and hope that it brings you to duna(the less then 20 percent thing is just so that someone can't just set the thrust limiter to 0.5% and get away with all the adjustment in the main burn itself).

once you power down to less then 20% and don't turn it completely off then it is then concidered part of the correction burn(s)

of course that is extremely difficult, so instead the winner will be the person with the lowest amount of delta v used to adjust combined between both burns.

If you're going to go to such lengths to make this difficult, then you really ought to explicitly outlaw McJeb and other fly-it-for-you systems like Precise Node, because making that sort of thing trivial is what they're all about. Also, I could easily cheat my way around these rules by using a tiny engine at full throttle for my orbital transfer stage, so if you really want to go this route then you ought to specify some minimum TWR rather than throttle or thrust limiter setting.

Quote

if you don't have a mod that allows you to see delta v then just take the amount of fuel used and divide it by the mass of the vessel after the adjustment burns to get your score (lower is better).

Why not just use the rocket equation? LN(wet wt./dry wt.)*ISP*9.82? Fuel is 0.5t/100U. I mean, I know this is rocket science but that part's pretty easy!

Quote

using monopropellent? then use the monopropellent engines. rcs thrusters are too complicated to work in.

RCS thrusters obey the rocket equation like everything else, so I'm not sure why it's too complicated. You could always make people calculate the dV based on the otherwise dry weight of the craft to insure they get no extra dV for the convenience of using RCS. Disallowing it only makes the process of correction really tedious because you have to keep re-orienting your ship to make small adjustments. Anyway, I'm not trying to be  a wet blanket, but I think with a little more thought this could become a fairly interesting challenge. However IMO you are not quite there yet.

 

Edited by herbal space program
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10 minutes ago, herbal space program said:

If you're going to go to such lengths to make this difficult, then you really ought to explicitly outlaw McJeb and other fly-it-for-you systems like Precise Node, because making that sort of thing trivial is what they're all about. Also, I could easily cheat my way around these rules by using a tiny engine at full throttle for my orbital transfer stage, so if you really want to go this route then you ought to specify some minimum TWR rather than throttle or thrust limiter setting.

Why not just use the rocket equation? LN(wet wt./dry wt.)*ISP*9.82? Fuel is 0.5t/100U. I mean, I know this is rocket science but that part's pretty easy!

RCS thrusters obey the rocket equation like everything else, so I'm not sure why it's too complicated. You could always make people calculate the dV based on the otherwise dry weight of the craft to insure they get no extra dV for the convenience of using RCS. Disallowing it only makes the process of correction really tedious because you have to keep re-orienting your ship to make small adjustments. Anyway, I'm not trying to be  a wet blanket, but I think with a little more thought this could become a somewhat new and interesting challenge. However IMO you are not quite there yet.

 

1. I bet a lot of people would see that equation and be turned away from the challenge (people that don't understand that equation can still do the challenge half decently).

2. it may be less accurate but it's just easier to use the fuel used during the correction burns divided by the mass of the vessel after the correction burns.

3. yes I'm going to outlaw mechjeb but in what I have seen from mechjeb it isn't very good at going from ground to duna transfer in one burn.

4. again with the easier way of doing things it's just easier not to use rcs at all.

5. most of that is just so the challenge isn't so math oriented, the idea of the challenge was to see if you could be accurate enough with the controls to in the main burn so that you would use the least amount of delta v in mid course corrections.

6. I know a lot of people like to be very math oriented when it comes to this game but a lot of people don't care for the fine details, they just want to see if they can do it.

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46 minutes ago, rockets-don't-make-toast said:

1. I bet a lot of people would see that equation and be turned away from the challenge (people that don't understand that equation can still do the challenge half decently).

To be fair, if you're considering a direct ascent to Duna and back with a single burn, you're probably way past the rocket equation.

I guess you could either brute force it and burn straight to Duna consuming immense amounts of dV, or work out some math and launch at the right moment. The second method would save plenty dV, but would require a bit more planning than the first one.

Once you know where / in which direction to launch, the challenge is far from impossible (the hardest part might be landing on Duna without engines).

 

I don't have much time to try it myself, but I'd enjoy seeing how people did it. If you have already done it yourself, posting a few screenshots of your attempt might give other players an incentive to do it too.

Edited by Gaarst
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7 hours ago, Gaarst said:

Once you know where / in which direction to launch, the challenge is far from impossible (the hardest part might be landing on Duna without engines).

I think the way around that would be by starting that second burn before touching down, and just making sure that your TWR on Duna is <1 at 25% throttle. Nothing in the rules says you have to stop burning just because you've touched down. Also come to think of it, I've built a Duna-and-back capable SSTO in the past. Taking that to orbit happens at full throttle the whole way, after which ejecting to Duna on the nukes at >20% throttle the whole way would probably just be a matter of working out the right timing.  One could then do a powered touch-and-go on the landing leg, never going under 20% throttle, and take right back off into Duna orbit and back home. I guess for that the hardest part would be landing it deadstick on Kerbin directly from the transfer trajectory, but I actually just a couple of days ago (as part of @Joseph Kerman's challenge ) managed to aerobrake into Laythe with a spaceplane, from a just survivable atmospheric capture into a 50X52 km orbit, using only 1m/s of dV to circularize at the end. once I'm done with that challenge, maybe I'll try that approach to this one...

Edited by herbal space program
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