omelaw

what was the lowest Dv margin you haved for a flight?

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no screenshot, sorry.

but I had a 4 man mun orbiter with a single manned lander, after I do some science on mun highland and redocked it on mun orbit.

and

so I flip the ship and used the lander's engine..... 7m/s short.

then I realized I didn't decopeler that connect orbiter's engine and heatshield. so I load quicksaved..

I burn my engine for get aerobreaking on kerbin... and the poodle stoped, 18.4m/s short.

decouple engine ... Dv 0.4m/s

and run lander engine, 0.3m/s short but periaps in atmo.

 

 

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Running out of fuel 0.5m above the muns surface. So 0dv! :) After a few thousand hours of game-play this will happen a lot!

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I mostly do SSTOs and there were many cases when I spent all my fuel to get my trajectory to slightly dip into to atmosphere and then spent an hour waiting for drag to bring me down.

So probably 0? Or even less than 0 if we count the times when I had to push my craft with kerbals to get home. :)

Edit: On the other hand, there were also times when I returned home with half of my rocket still intact... from Eeloo.
 

Spoiler

This was before the ARM patch, so orange tanks were the largest in the game.

dIhWdEN.png

 

Edited by theend3r

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I've returned completely dry a couple of times. Still, I did have enough to get into a re-entry trajectory and a bit less would have sufficed, I'm sure. I think the closest to zero must've been a re-entry where my Pe ended up well over 60k. It took forever and a day to get from that to splashdown.

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I was testing a Duna lander design a few months back and ended up 35 m/s short of a stable 59km orbit. Fortunately I had over-designed the system with monoprop. I made the rest of the burn with RCS and then went back to the drawing board - the next more definitive version doesn't have the same problem. :) (smaller monoprop tanks on the next iteration resulted in more overall dV for the lander and still enough monoprop for orbital docking ops with the main crew vehicle).

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Long time ago on the return from my first ever Duna landing (and before re-entry heating), I had to jettison the life support container in order to make the return manoeuvre... so technically about -50m/s. 

Spoiler

7VCISTF.jpg

 

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I'm playing again since 1.2pre :-)

0.6 m/s, returning from Minmus during in a career game with a standard rocket. "Normally" it's around 30-200m/s from within Kerbin SOI just because i know my designs. (A little) more from other planets depending on transfer window and ISRU.

 

Edited by Green Baron

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When making replicas of the Atlas V launch vehicles (scaled to KSP but keeping a similar aesthetic) one of them (I believe it was the 431 variant) reached a 75km orbit with its maximum payload with only around 5m/s remaining. Although that was an interesting launch, because the vehicle had around 3450m/s initially, and when using MechJeb, that is usually at least 150m/s less than it needs to reach orbit. So by MechJeb's usual standards, I made orbit with around 150m/s less than it should've taken (I think what happened was that the uneven SRB placement gave the rocket a bit of extra horizontal velocity and therefore forced MechJeb to use a slightly more efficient trajectory).

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There was one time one of my Kerbals had to get out and use his EVA pack to push against the heat shield and slow down the pod.

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22 minutes ago, Vingo said:

-50 dv. it involved litho breaking though

I see what you did there.

Anyways the lowest dv margin I had on a space mission was pretty much the same as @Majorjim!, except that I ran out of fuel more around 10m above the surface. Impact blew up two of my four landing legs as well as my descent engine. Luckily nothing on the ascent stage blew.

I've had some aircraft that I've had to glide back to the KSC, and only barely made it.

Edited by EpicSpaceTroll139

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I was docking something to a mothership. I had 4m/s of DV left.

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The day I sent a Mk3 SSTO to Minmus, after the return burn I had only fuel for the fuel cells... did a 5 pass aero-brake and by adjusting pitch during passes I managed to glide and land at KSC... :P
U4Ardo8.jpgDzu8brp.jpg

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Without running low on fuel, it was still way more than I needed. I always try to make my ships bigger than they need too be. If you count running out of fuel then I have about 15 different times that left Kerbals stuck somewhere with no return. Most of these were in 1.0.5. 

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8 hours ago, Majorjim! said:

Running out of fuel 0.5m above the muns surface. So 0dv! :) After a few thousand hours of game-play this will happen a lot!

My first Moho landing went about like that.  Had to try the suicide burn 3-4 times in order to get it perfect.  The best I could do was running out of fuel at about 5m above the surface, with ~15m/s touchdown speed.  The good thing is I was using structural parts for legs, so nothing exploded.  So descent stage = empty on touchdown, ascent stage = full. 

So count me in the 'negative Dv margin' crowd for that one.

My normal launches to LKO usually end with <50m/s of remaining fuel in the ascent stage once the design has been refined/ascent optimized/payload maximized.

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Zero for a successful mission. I've had to have the kerbal get out and push to get home before.

If we look at failed missions, around -1500m/s. Stupid Moho and the lying dV maps. :mad:

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2 minutes ago, Red Iron Crown said:

If we look at failed missions, around -1500m/s. Stupid Moho and the lying dV maps. :mad:

I've found that it's good to have at least 7km/s for Moho (if aerobraking on the way back). It usually ends up being way too much, but if you have an unlucky transfer then your margin might be pretty low.

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13 hours ago, Majorjim! said:

Running out of fuel 0.5m above the muns surface. So 0dv! :) After a few thousand hours of game-play this will happen a lot!

My favorite was running out of fuel a couple of meter before landing on Tylo. Two side boosters on rover, mechjeb decent. 
Ran out of fuel, landing legs was down and the impact destroyed legs and boosters leaving the rover free to drive :)

Else 12 m/s on an Minmus landing with an 90 ton ship in 1.2

Has done many landings on Kerbin there I spare a few m/s to burn on touchdown but that don't count I think. 
 

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I once did a trip to Eeloo (manned) and ran out of fuel while setting up my departure from Eeloo. I was lucky to have a bit of mono prop left and used that to fine tune my reentry to Kerbin. It took a couple tries and reloads but I managed to find the sweet zone and safely reentered without even skipping out of the atmosphere. This was the most awesome mission I've ever managed and doubt I'll ever get close to this again!

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In the 1.2 pre-release I had pretty much an ideal mun trip.  This was an Apollo-esque mission with a separate lander and munar ascension and command module.  I landed with 10dV left in the lander stage.  I rendezvoused with 0 dV and had to use a little of my RCS to slow but I had plenty (note: I didn't have an RCS tank, just the 10 units in the lander can).  Finally I got a re-entry trajectory from the Mun to Kerbin with about 30dV left.  The only place I wasted fuel was the lifter, I had just grabbed my standard lifters and It was a 7 ton lifter for a 6 ton craft.

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One of my first Duna missions: Despite not moving far away from Kerbin, I was sick of the trial and error portion of building, so I had started using KER to get proper readouts during construction. This had left me with a craft that on paper looked like it'd work. I also had KAS installed, as I liked doing assembly in orbit. Because using KAC from early on, I had pretty much solely relied on launch-to-encounter, as it's more efficient, and a lot more fun.

The orange three were about to take of Duna, but with lower dV remaining than I was comfortable with. I sent an engineer out to remove some parts that were deemed not critical: A few extra battery packs, the antenna (afterall, they were bringing the entire thing back home, no need to transmit), and all but one solar panel that I made sure to keep in the shade during the transit back to Kerbin. I also removed some empty TAC-LS containers.

I then launched, making sure not to let a single fart in the spacesuit go to waste for the little extra thrust I could get out of it. As soon as I was high enough to somewhat safely EVA around the ship (still it Dunas atmosphere), I sent out the engineer again to remove the landing legs. It was a pain in the aft to fight the atmespheric drag, but he eventually did it and got inside. The pilot started burning again, and I ended up getting a pretty much perfect escape angle, eventually resulting in a Kerbin encounter. Kerbin periapsis at 35km, which was as low as I dared go with Deadly Reentry. I then concluded that I had no choice but to hope for the best, as I only had 3m/s of dV remaining. From there on it was just a matter of coasting back and let the atmosphere do the rest. The 35km periapsis turned out to be perfect: It slowed me down for a capture, and after looping around Kerbin once I finally reentered for a "safe" landing. (somewhat harder than desirable due to stripping of some parachutes before departing Duna).

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Not counting times I've actually run out of fuel...

 

In my last stock game run (modded; stock as opposed to RSS) I did a tourist contract to take two tourists on a flyby of both the Mun and Minmas.

Went up with (if I remember rightly) 859m/s

Used a Munar gravity assist to kick me out to Minmas, with a small correction burn

Didn't have enough fuel to get home straightaway, so I burned for another Munar flyby (something like 50m/s short)

With the Munar gravity assist I ended up with a PE of 44km and 2cm/s left in the tank.

I was really stoked, because that was the first mission that I've sent up with the intention and need to use gravity assists because I didn't have enough fuel.

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In the 1.2-pre, I had a multi-hop ISRU mission that ran out of fuel during my last retro-burn to land on the Mun, did not even notice that I had 0 units of fuel left until I started mining.

If I had had to fly that mission again, I would not have launched with an empty LF tank, and probably would not have used the Mk3 to 2.5 adapter for launch-stage fuel(both to be refueled with LF at the first stop)

I forgot that the empty fuel tank is a trick I use for interplanetary missions with a refuel stop on Minmus, not as part of Mun-Minmus-Kerbol training/tourism missions.

I miss my KER read-outs.

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I posted this about a month ago. 3 m/s remaining as I touched down on Mun.

 

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I have been playing a hard no save/no revert so my margins have been pretty big. I did send a station with a lander to minimus.  I forgot to turn off the Fuel reserved for the lander so KER told me I had more dv then I actually had.  After some inefficient manavours I get set up right where I want to be with 50 dv left (according to KER).  I then disconnect the lander and the engine was dead.....  Upon inspection the Stations main engine had used the landers fuel.  I had originally planed about 2500 dv for the lander.  After reconnecting to the station (had to use a kerbal to dock it back as it had no RCS) and stealing the landers fuel back it had about 1400 dv.  So I probably had a margin of -1100 dv aka mission soft failure

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