Delta-V Race to Laythe in an SSTO

[Joseph Kerman]

As one can tell, Matt Lowne did a video showcasing a Laythe SSTO with 4025 m/s dV in LKO. So my challenge will be, can you do better? Could you make the most out of as little dV as possible?

Here are the rules:

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1) No dirty cheating alpacas (no debug menu)

2) You must have either a video or a full album of the mission

3) KER must be installed

4) No mods (besides KER)

5) You must show the Resource Tab always if you make a video

6) You must bring at least 10 passengers with 2 pilots to Laythe and back

7) Finally, you have to have clear knowledge of gravity assists

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Leaderboard:

1st place: @herbal space program, 3390 m/s (Yay, you get your first badge)

2nd place: @Matt Lowne, 4025 m/s

3rd place: @Firemetal, 6250 m/s

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So build away, intrepid builders. May the Best SSTO win!

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Oh yeah, anyone who at least beat Matt's score gets a badge (WIP).

Edited July 13, 2017 by Joseph Kerman

[Human Person]

Where do I start counting my delta-v? in LKO? Does it have to be an SSTO?

[Joseph Kerman]

1 hour ago, Physics Student said:

Where do I start counting my delta-v? in LKO? Does it have to be an SSTO?

dV in LKO, and an SSTO, like Matt.

[Matt Lowne]

It would actually be pretty easy to beat my record, that SSTO was very heavy so burns were quite long and therefore not the most efficient. Plus the flight to Jool could have been trimmed using better gravity assists. 

[herbal space program]

I'm pretty sure I can smoke this thing unless certain other old-timers show up, but I have some questions first:

Are we counting the dV required to get to the ground and back into orbit at Laythe?

If not, do we still need to land and go back to orbit?

Is what you are asking for actually the lowest expenditure of vacuum dV from LKO back to LKO? That is, if I make LKO with say 5km/s dV based on my nukes and get back there with 2km/s, will that count as using only 3km/sec dV, or do we need to do some messy calculations with dV in air at Laythe on the Rapiers? I've never used KER, so I don't know how it calculates. If you know the dry mass of your craft and the ISP of the engines, remaining vacuum dV for a particular stage is dirt simple to calculate using the rocket equation, so that's what I've always done, but I guess I can install and use KER to do that if necessary.

 

PS: Is there a link to Matt's video somewhere? I don't know where to find it.

 

Edited June 25, 2017 by herbal space program

[qzgy]

32 minutes ago, herbal space program said:

PS: Is there a link to Matt's video somewhere? I don't know where to find it.

 

Here you go. (there is also somewhere a commentary video)

[herbal space program]

35 minutes ago, qzgy said:

Here you go. (there is also somewhere a commentary video)

Thanks! I can see now that he did use the famous @PLAD K-E-K-K-J route outbound, but there are definitely some inefficiencies in the Jool system segment and the return that could be improved upon, so worth it for me to try...

Edited June 25, 2017 by herbal space program

[Firemetal]

6250 in an SSTO was my best. (Yeah I suck) I'll post the link to the mission report in a bit.

Here it is.

Fire

Edited June 25, 2017 by Firemetal

[Joseph Kerman]

3 hours ago, Firemetal said:

6250 in an SSTO was my best. (Yeah I suck) I'll post the link to the mission report in a bit.

Here it is.

Fire

Nice. But that is about as far as you can get?

[Firemetal]

Just now, Joseph Kerman said:

Nice. But that is about as far as you can get?

Well, others have gotten further and so can I. But I have tried to do this many times before and failed. This version barely made it. I may attempt it again sometime in the future. But that is it for now.

Fire

[Joseph Kerman]

anyone?

[herbal space program]

7 hours ago, Joseph Kerman said:

anyone?

Have you ever tried this yourself? This takes a lot of time!  

I've actually got my ship built and on LKO now, which was a challenge in itself since we need to ship 12 Kerbals, but the fun has only started.....

 

Edited June 27, 2017 by herbal space program

[Joseph Kerman]

10 hours ago, herbal space program said:

Have you ever tried this yourself? This takes a lot of time!  

I've actually got my ship built and on LKO now, which was a challenge in itself since we need to ship 12 Kerbals, but the fun has only started.....

 

I am just budding in interplanetary SSTO making. A 100-Kerbal SSTO to Duna, I just barely made it there, and now I am not so sure about the craft. I have no KER, so I have no idea if I can get anywhere.

 

Craft file: https://mega.nz/#!9rggDAxD!L8I49cp_l3LKI6IQO3MezDkV5f0g_0pDD2xn5L0gblY

[herbal space program]

On ‎6‎/‎27‎/‎2017 at 7:50 PM, Joseph Kerman said:

I am just budding in interplanetary SSTO making. A 100-Kerbal SSTO to Duna, I just barely made it there, and now I am not so sure about the craft. I have no KER, so I have no idea if I can get anywherre

I hardly consider 100 Kerbals to Duna Budding!  Seriously, If you landed something that size on Duna horizontally, you're doing really well!

I haven't had a chance to download and look  at your ship yet, but I think I can help you on the getting anywhere score:

1) Behold, the rocket equation!: dV = ln(wet mass/dry mass)*ISP*9.82. It's really pretty simple to use. To make a handy Excel spreadsheet, put your engine ISP in cell A2, your dry weight in B2, your starting fuel (units of LF + Ox if applicable) in C2, and your ending fuel in D2. Then paste this formula into E2: =LN(($B2+(C2*0.005))/($B2+(D2*0.005)))*$A2*9.82 and Voila!  now you know your deltaV for whatever quantity if fuel you want to burn at a given ISP and dry weight.

2) If you want to know how much dV it takes to get from A to B, take a gander at this:

Between those two things and knowing your TWR in local gravity you can easily figure it out. Unless of course you want to get into gravity assists, but that's a topic for a later post on this thread.....

Edited June 29, 2017 by herbal space program

[Joseph Kerman]

5 hours ago, herbal space program said:

I hardly consider 100 Kerbals to Duna Budding!  Seriously, If you landed something that size on Duna horizontally, you're doing really well!

I haven't had a chance to download and look  at your ship yet, but I think I can help you on the getting anywhere score:

1) Behold, the rocket equation!: dV = ln(wet mass/dry mass)*ISP*9.82. It's really pretty simple to use. To make a handy Excel spreadsheet, put your engine ISP in cell A2, your dry weight in B2, your starting fuel (units of LF + Ox if applicable) in C2, and your ending fuel in D2. Then paste this formula into E2: =LN(($B2+(C2*0.005))/($B2+(D2*0.005)))*$A2*9.82 and Voila!  now you know your deltaV for whatever quantity if fuel you want to burn at a given ISP and dry weight.

2) If you want to know how much dV it takes to get from A to B, take a gander at this:

Between those two things and knowing your TWR in local gravity you can easily figure it out. Unless of course you want to get into gravity assists, but that's a topic for a later post on this thread.....

I never landed the craft anywhere...

[herbal space program]

On ‎6‎/‎29‎/‎2017 at 5:58 PM, Joseph Kerman said:

I never landed the craft anywhere...

 

I would say that landing a spaceplane on Duna is up there among hardest things I've done.

http://imgur.com/a/oKMLa

The whole bouncing off the ground and then landing upside down and exploding thing is just murder. Also too the very thin air. Doable though! And getting home is a total breeze by comparison.

Edited July 7, 2017 by herbal space program

[Firemetal]

Didn't think I could do better, but I did. Over 2000 m/s better! Still doesn't beat Matt's though. Video, stats, and craft file coming soon.

Fire

[herbal space program]

OK, here's my final entry. Total dV expended from LKO-Laythe ground-Kerbin ground: 3390m/s. Here's the final album:

http://imgur.com/a/rkYEZ

Don't know why it won't embed, any advice on that would be appreciated. I flew this whole mission by hand with a Nintendo controller, and aside from KER my only computational aids were a calculator and a couple of Excel spreadsheets I made. My plane ships 12 Kerbals as required and makes LKO with 4966m/s in the tank. It weighs about 105t on the runway, with a dry weight of around 43t, and uses 5 Rapiers + 4 Nervs, It took a total of 1263m/s to get to a Jool  encounter, 1304 to get to low Laythe orbit, 1308 to get to the ground on Laythe, and 2371 to get back to low Laythe orbit. Outbound, in addition to a slightly messed-up version of the Plad KEKKJ assist route, I used 4 successive encounters inside the Jool system to get to a survivable Laythe atmospheric entry, as illustrated in the album. From there all it took was an 8m/s de-orbit burn to get to the surface. My best performance among many attempts  getting back to LLO from there was 1033m/s for a total of 2371.From there, I was ultimately able to get back to a Kerbin transfer orbit using Tylo for 681.5 m/s. From my initial Jool transfer orbit, which hits the top of Kerbin atmo at a blazing 4100m/s, I swung around Kerbin to drop to a slightly less than 2:1 resonant orbit, then did a 140m/s DSM near the subsequent solar apopapsis to raise my PE back to Kerbin's orbit and set up another Kerbin encounter there. I thought that would be enough to give me a survivable aerocapture, but as it turns out even that ~3600m/s entry was still too fast for me to get captured without something exploding. I ended up having to do a combined aerobraking-gravity assist maneuver from there to drop to a 3:2 resonant orbit, requiring another 90m/s DSM to finally get to a survivable Kerbin aerocapture. From there, it took only another 15m/s for me to get to LKO and then the ground. Sorry, I did not land on the runway, although with enough tries I'm sure I could have. Between the tight heating envelope for re-entry and the lousy aerodynamic trim of my ship at that fuel level, I just ran out of patience trying to deadstick it to the exact right spot.

I really thought I could do better than this, but clearly I underestimated how big a problem re-entry heating would be in this version. If I were going to do it again, I guess I would have more shielding, radiators, aerobrakes, etc., although sticking all that stuff on an SSTO spaceplane is kind of inelegant IMO. Perhaps the Mk3 parts would perform better also, as that Mk2 cockpit really got hot quickly. In any case, This run beat the current leader by 635m/s, but I believe that with a more heat-resistant design and somewhat better planning the 3000m/s mark is definitely attainable. I hope somebody comes along to prove that true, but missions like this are a big commitment . For those new to this kind of stuff, I think the album will illustrate a couple of useful strategies for saving fuel, and I hope somebody will find it helpful in that regard. On thing I'd like to point to in particular is the strategy of using a combination of gravity assists and DSM's to climb a ladder of resonant orbits out of your parent body. Using this strategy, you can get pretty much anywhere from LKO for <1500m/s, around 1377 to get to Jool capture, using only Kerbin for gravity assists. Juno used this strategy, and I made an album about it a while back: http://imgur.com/a/XQSnn.

Off to make another Duna spaceplane....

Edited July 13, 2017 by herbal space program
updating progress some more

[herbal space program]

Just dropping a new post to tell OP that I'm finished with this challenge. Please see my post directly above for details...

[Bottle Rocketeer 500]

@herbal space program Can you please tell me the time (in kerbin time) you launched, as I haven't yet found any such windows for K-E-K-K-J transfers.

[NISSKEPCSIM]

Might try this after I get a certain project out of the way...

[herbal space program]

On ‎6‎/‎24‎/‎2017 at 2:37 AM, Joseph Kerman said:

 

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2nd place: @herbal space program, 4966 m/s

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Really? You're scoring me only on how much dV I had on LKO and not how much I actually used to get Laythe and back?  I took considerable pains in my album to show that I only used 3390m/s of the 4966 I had on LKO to finish the mission. You can see that when I am back on the ground on Kerbin, I still have 1,924 LF on board.  Are you really going to penalize me 1.584m/s just because I hauled it all the way to Laythe and back without using it? Please reconsider. I spent a crazy amount of time planning, flying and documenting this mission, sparing every m/s I could in all sorts of ways, and scoring me just on what I had in the tank on LKO and not what I actually used trivializes that large effort. Launching with less fuel would actually have made the mission easier not harder because I would have had a better TWR for my orbital maneuvers.

Please note: OP did acknowledge my actual score in response to this, so the matter has resolved very much to my satisfaction 

Edited July 13, 2017 by herbal space program

[herbal space program]

4 hours ago, Bottle Rocketeer 500 said:

 Can you please tell me the time (in kerbin time) you launched, as I haven't yet found any such windows for K-E-K-K-J transfers.

I ejected from Kerbin on Y2, d164, which is the first such window, but in hindsight I don't recommend that one. I kept arriving at my second Kerbin encounter too early. These routes were figured out by @PLAD, who has a series of them listed in his posts. I believe the second window was right around the first day of year 4, but if you contact PLAD or look through his post history a bit, I'm sure you can find the exact number. If you just look at how the ejection burn is set up in my album, you can see what it should look like in terms of how the bodies are aligned.

Edited July 13, 2017 by herbal space program

[tseitsei89]

1 hour ago, herbal space program said:

Really? You're scoring me only on how much dV I had on LKO and not how much I actually used to get Laythe and back?  I took considerable pains in my album to show that I only used 3390m/s of the 4966 I had on LKO to finish the mission. You can see that when I am back on the ground on Kerbin, I still have 1,924 LF on board.  Are you really going to penalize me 1.584m/s just because I hauled it all the way to Laythe and back without using it? Please reconsider. I spent a crazy amount of time planning, flying and documenting this mission, sparing every m/s I could in all sorts of ways, and scoring me just on what I had in the tank on LKO and not what I actually used trivializes that large effort. Launching with less fuel would actually have made the mission easier not harder because I would have had a better TWR for my orbital maneuvers.

 

Agreed. Scoring like this is just stupid...

[PLAD]

3 hours ago, herbal space program said:

I ejected from Kerbin on Y2, d164, which is the first such window, but in hindsight I don't recommend that one. I kept arriving at my second Kerbin encounter too early. These routes were figured out by @PLAD, who has a series of them listed in his posts. I believe the second window was right around the first day of year 4, but if you contact PLAD or look through his post history a bit, I'm sure you can find the exact number. If you just look at how the ejection burn is set up in my album, you can see what it should look like in terms of how the bodies are aligned.

Yup, that is the first KEKKJ window start date. It's in Kerbal time (6/426) though, in my old posts I do it in Earth time (24/365), so my old K146-E195.7-K296.2-K509.25-J821 becomes the following in Kerbal time (which pretty much everyone uses now):

K y2 d155 - E y2 d353.7 -K y3 d330 - K y5 d330 - J y8 d299.   Note that the Kerbin start window is wide, I leave on the early side (y2d155) because I use the Mun for an additional boost, and 48 hours later like hsp did is also OK. (Heck, all the times are flexible if you are willing to use more dv for corrections on the way, though the Eve flyby time is the most critical to get right.)

@herbal space program, excellent mission by way!