Ultralight challenge: Lowest launchpad mass to orbit and beyond

[flashcactus]

Not really an entry as its just a tweak to the Timmy Tiny by swapping out the Oscar-Bs for a Round-8 and adjusting the fuel in the FL-T100. Gives a bit more dV and reduces the weight a little.

I make it 0.784+0.005=0.789t.

MechJeb will put it into a stable 71K orbit.

(Unless its different enough to count as an entry...)

Well, given that almost all the base-challenge non-tweakscale entries have been 2-stage rockets with an FL-T100 + Rockomax 48-7s as the first stage, and some combination of the OKTO2, OSCAR/Round-8 & LV-1 as the second, it's as different as one of these can be. I need an orbit+MJ or map+highlighted Pe shot to verify it, though, and the challenge rules also require a .craft file, which is probably not necessary here

[ihtoit]

mine's a single stage with useful payload. I think that deserves its own board, TBH.

[Foxster]

Well, given that almost all the base-challenge non-tweakscale entries have been 2-stage rockets with an FL-T100 + Rockomax 48-7s as the first stage, and some combination of the OKTO2, OSCAR/Round-8 & LV-1 as the second, it's as different as one of these can be. I need an orbit+MJ or map+highlighted Pe shot to verify it, though, and the challenge rules also require a .craft file, which is probably not necessary here

Well, OK then. Here you go...

0.784+0.005=0.789t (0.005 is for the solar panel)

...and a craft file...

https://www.dropbox.com/s/4zptiiiywihqjo7/Challenge%202.craft

Edited August 17, 2014 by Foxster

[Cat Biscuits]

Oh sry, I hope this does the trick, Im just lucky its easy to fly these runs are definitely helping me nail the whole gravity turn/terminal velocity thing, is good practice.

Im thinking a run at the moon next will make things more interesting

Edited August 17, 2014 by Cat Biscuits

[flashcactus]

Oh sry, I hope this does the trick, Im just lucky its easy to fly these runs are definitely helping me nail the whole gravity turn/terminal velocity thing, is good practice.

Okay, added.

Im thinking a run at the moon next will make things more interesting

Definitely will, especially since we have no non-ion moon landings yet .

[Foxster]

"Tom Thumb" Minmus lander...

1.446+0.025=1.471t

https://www.dropbox.com/s/9q7slnx7pl1qk39/Tom%20Thumb%20Minmus.craft

[Foxster]

"Tom Thumb" Mun lander...

1.859+0.026=1.885t

https://www.dropbox.com/s/ozd7mh705k2oco8/Tom%20Thumb%20Mun.craft

Edited August 17, 2014 by Foxster

[Cat Biscuits]

oh noes "no craft file provided"!

are my links failing?

https://drive.google.com/file/d/0B7eHPS0lfgpGUEl2WEhIclhHLUU/edit?usp=sharing

[flashcactus]

oh noes "no craft file provided"!

are my links failing?

https://drive.google.com/file/d/0B7eHPS0lfgpGUEl2WEhIclhHLUU/edit?usp=sharing

er sorry, didn't notice it Must be fixed now.

[flashcactus]

"Tom Thumb" Minmus lander...

1.446+0.025=1.471t

https://www.dropbox.com/s/9q7slnx7pl1qk39/Tom%20Thumb%20Minmus.craft

Okay, added.

"Tom Thumb" Mun lander...

1.859+0.026=1.885t

https://www.dropbox.com/s/ozd7mh705k2oco8/Tom%20Thumb%20Mun.craft

The link you provided seems to point to the same file as the previous one, so I'll have to ask you to re-upload this one first and link it.

[Foxster]

Link to Tom Thumb Mun craft updated.

[flashcactus]

Link to Tom Thumb Mun craft updated.

Okay, the mün craft is okay. Congratulations on being the first Exploration Mode entrant

[Heimdall5008]

Okay, my first challenge. After trying to optimize the fuel engines even more (and spectaculary failing) I changed my strategy and build a craft with the shiny new monopropellant engines.

The craft basiclly consists of 3 FL-R10 mono tanks, 1 tiny TR-2V stack seperator, 2 O-10 engines and an OKTO2 core. The top most tank (second stage) is only filled to 90%. To be able to operate the probe indefinatly in orbit I but a battery and 2 solar panels on it, but I can make orbit without them.

According to MJ the craft has 765 kg. Add each 5 kg for battery and solar panels and I come to 780 kg. The craft has dV of 3711 m/s (atmo) / 4892 m/s (vac) with a max TWR of 5.20 (first stage) / 15.91 (second stage).

With the help of Mechjeb I can put the probe in a stable 71 km orbit and have still 200 m/s left for deorbit (or some useful payload like a 2HOT ).

If someone can show me a site that accepts craft files I will upload it. At the moment I have not found a site that accepts this format.

/EDIT:

Okay, tested a bit further. My craft "Mono Orbiter" still works with only 85% monopropellant in the top tank. That are 20 kg down again.

So new stats are 760 kg / 745 kg with 50 m/s left in 71 km orbit.

Edited August 17, 2014 by Heimdall5008

[Foxster]

Okay, my first challenge. After trying to optimize the fuel engines even more (and spectaculary failing) I changed my strategy and build a craft with the shiny new monopropellant engines.

http://s1.directupload.net/images/140818/temp/imcvp3vw.jpg

The craft basiclly consists of 3 FL-R10 mono tanks, 1 tiny TR-2V stack seperator, 2 O-10 engines and an OKTO2 core. The top most tank (second stage) is only filled to 90%. To be able to operate the probe indefinatly in orbit I but a battery and 2 solar panels on it, but I can make orbit without them.

According to MJ the craft has 765 kg. Add each 5 kg for battery and solar panels and I come to 780 kg. The craft has dV of 3711 m/s (atmo) / 4892 m/s (vac) with a max TWR of 5.20 (first stage) / 15.91 (second stage).

With the help of Mechjeb I can put the probe in a stable 71 km orbit and have still 200 m/s left for deorbit (or some useful payload like a 2HOT ).

http://s14.directupload.net/images/140818/temp/d34c2zv4.jpg

http://s1.directupload.net/images/140818/temp/wnesb68w.jpg

If someone can show me a site that accepts craft files I will upload it. At the moment I have not found a site that accepts this format.

/EDIT:

Okay, tested a bit further. My craft "Mono Orbiter" still works with only 85% monopropellant in the top tank. That are 20 kg down again.

So new stats are 760 kg / 745 kg with 50 m/s left in 71 km orbit.

Did you add 2x0.09 for two massless engines? If not then I make that 0.760+0.18=0.94t

[Cat Biscuits]

Oh I used googledrive for my craft file, can store anything, you would just have to learn how to share a folder via hyperlink.

[flashcactus]

Okay, my first challenge. After trying to optimize the fuel engines even more (and spectaculary failing) I changed my strategy and build a craft with the shiny new monopropellant engines.

http://s1.directupload.net/images/140818/temp/imcvp3vw.jpg

The craft basiclly consists of 3 FL-R10 mono tanks, 1 tiny TR-2V stack seperator, 2 O-10 engines and an OKTO2 core. The top most tank (second stage) is only filled to 90%. To be able to operate the probe indefinatly in orbit I but a battery and 2 solar panels on it, but I can make orbit without them.

According to MJ the craft has 765 kg. Add each 5 kg for battery and solar panels and I come to 780 kg. The craft has dV of 3711 m/s (atmo) / 4892 m/s (vac) with a max TWR of 5.20 (first stage) / 15.91 (second stage).

With the help of Mechjeb I can put the probe in a stable 71 km orbit and have still 200 m/s left for deorbit (or some useful payload like a 2HOT ).

If someone can show me a site that accepts craft files I will upload it. At the moment I have not found a site that accepts this format.

/EDIT:

Okay, tested a bit further. My craft "Mono Orbiter" still works with only 85% monopropellant in the top tank. That are 20 kg down again.

So new stats are 760 kg / 745 kg with 50 m/s left in 71 km orbit.

Nice one, but you have to count the monoprop engines too (they're massless). That's also a great opportunity to throw those solar panels&batteries away in order to not count them. I'd also recommend draining one of the bottom tanks instead of the top one, you could remove more fuel this way without sacrificing delta-v.

As for where to upload stuff, Google drive & Dropbox both seem to be popular choices, Mediafire is a decent file hosting site, and the ultimate solution would be to get yourself your own website and host all that stuff there, as I do. I have a paid fancy domain&virtual server, but if you don't want anything but a place to upload files, a free alternative will do just fine.[spoiler=]http://host-ed.me is a nice hosting if you choose to actually do that

[Heimdall5008]

Did you add 2x0.09 for two massless engines? If not then I make that 0.760+0.18=0.94t

No, I did not know that they were massless, I thought only parts with drag 0 are not counted. My bad. Can I find somewhere a list which parts are considered massless or to get the real weight of the craft?

But 0,94 t is still good I think

/EDIT:

Nice one, but you have to count the monoprop engines too (they're massless). That's also a great opportunity to throw those solar panels&batteries away in order to not count them. I'd also recommend draining one of the bottom tanks instead of the top one, you could remove more fuel this way without sacrificing delta-v.

Thank you for the tips. I incorporated them and know have the following craft:

MonoOrbiter.craft

880 kg complete (added the 11 parts myself this time ), 685 kg massless, with the option to reduce it to 865 kg.

The bottom tank is only filled to 40% and I still have 20 m/s left in orbit:

Edited August 18, 2014 by Heimdall5008

[flashcactus]

Can I find somewhere a list which parts are considered massless or to get the real weight of the craft?

http://wiki.kerbalspaceprogram.com/wiki/Massless_part

The easiest way to determine whether you have to add the part's mass manually is to remove it from the vessel and see whether the mass shown by MJ/KER changes. If it doesn't, it's massless.

Edited August 18, 2014 by flashcactus

[Heimdall5008]

http://wiki.kerbalspaceprogram.com/wiki/Massless_part

The easiest way to determine whether you have to add the part's mass manually is to remove it from the vessel and see whether the mass shown by MJ/KER changes. If it doesn't, it's massless.

Thanks, seems logical.

Also now tested it without battery and solar panels. Mechjeb adds 5 electric charge, after the circulazation burn I had 6,3 charge left. Just engough to fire up SAS and burn the remaining 20 m/s retrograde before I dropped under the 5 charge from Mechjeb.

[Foxster]

Some musings on dV and orbit...

71Km orbit seems like a good target. Its above the absolute minimum for a stable orbit and allows for some slight errors in ascent.

4550 seems to be about the lowest launch delta V to get there.

If using multiple stages then the TWR on the first stage needs to be good enough to reach terminal velocity early on - but don't exceed it, use "limit to terminal velocity" in Mechjeb. This will be a TWR of 2-4 or so. Less than 1.6 and a 4550 craft will struggle to make orbit.

If using Mechjeb then tweaking the ascent path of a craft with 4550 dV that is failing to reach orbit might claw back just enough dV. For a fast craft (high TWR first stage) I find a start turn altitude of 4.5K and a turn shape of 45% leaves 50dV by orbit on a craft with 4551 at launch.

[flashcactus]

Some musings on dV and orbit...

71Km orbit seems like a good target. Its above the absolute minimum for a stable orbit and allows for some slight errors in ascent.

4550 seems to be about the lowest launch delta V to get there.

If using multiple stages then the TWR on the first stage needs to be good enough to reach terminal velocity early on - but don't exceed it, use "limit to terminal velocity" in Mechjeb. This will be a TWR of 2-4 or so. Less than 1.6 and a 4550 craft will struggle to make orbit.

If using Mechjeb then tweaking the ascent path of a craft with 4550 dV that is failing to reach orbit might claw back just enough dV. For a fast craft (high TWR first stage) I find a start turn altitude of 4.5K and a turn shape of 45% leaves 50dV by orbit on a craft with 4551 at launch.

Nice analysis. I'd go for a 70k initial apoapsis though, as it actually allows more wiggle space for an orbit with the same SMA (as kerbin's atmosphere ends at 69 077.553 m). Also, this is considerably different when using the FAR atmospheric model, where not throttling down and punching through the lower layers tends to be a better and more fuel-efficient approach.

[01010101lzy]

Okay I just found one on Baidu Tieba (Chinese website...)

The owner just posted a picture of it reaching orbit.

(Translated Chinese into English)

I made one as same as his(Mass=1.265t, dV=5372m/s, TWR=2.42)

then a lighter one(mass=0.703t, dv=4275m/s, twr=4.35)

Enough to reach orbit!

.....

so that's all.

---

Moderator Comment: Your links were broken. I removed them so you could fix if desired.

Welcome to the forums!

~Claw

Edited August 22, 2014 by Claw
broken links

[styxnpicks]

600kg to orbit 4 parts