Minimal Orbital

[Bluejayek]

Put this craft into a stable orbit above the atmosphere.

The craft consists of a (nonstock) 0.01 mass ASAS (because I\'m a bad pilot and have no joystick), a half tank of fuel, a full tank of fuel, and a lander engine.

This is the closest I have come:

If you want to take off the ASAS because you\'re actually a good pilot, go ahead, bonus points

Without the ASAS, this would be, as far as I know, the smallest craft capable of making orbit.

The ASAS module is attached.

Mainly, I am posting this because I am convinced it is possible to orbit with this, but I have been trying for a couple hours and havent managed it.

Edit: One final note. This will not take off immediatly, it is too heavy. You have to throttle to full, and wait for about 20% of the top tank to burn off before it leaves the ground.

Congratulations to Romfarer for the first successful manual orbit of this craft. Also to The_Duck for the first orbit of any type (Mechjeb assisted). Bluejayek (myself) has also been successful in orbiting this craft manually.

The new challenge is to put this into a stable orbit above the atmosphere, complete at least one orbit, and return the kerbals SAFELY to the surface. This will require a fully powered landing as there is no parachute available.

Congrats Romfarer for succesfully returning his Kerman to solid ground!

[UmbralRaptor]

In principle, it has a good enough mass ratio for orbit. However, the TWR is a nightmare. It might be easier with an LV-T30 or 45. >_>

edit: best I\'ve done with this is ~2100 m/s at ~55 km. Grr...

[Bluejayek]

In principle, it has a good enough mass ratio for orbit. However, the TWR is a nightmare. It might be easier with an LV-T30 or 45. >_>

edit: best I\'ve done with this is ~2100 m/s at ~55 km. Grr...

Those two engines are too heavy. They add 1.5 mass to the orbiter, and considering the dry mass of this is only 2, thats almost double.

One other thing to consider is dropping the second half tank entirely. It reduces the dry mass by 0.2, and also increases the TWR by a significant ammount. I have gotten to around 50km/2000m/s with that setup, but I don\'t think it has quite enough juice to make it all the way.

[UmbralRaptor]

Those two engines are too heavy. They add 1.5 mass to the orbiter, and considering the dry mass of this is only 2, thats almost double.

It\'ll still have enough ?V. eg: What Foamyesque did back in February.

[Bluejayek]

What foamy did was the absolute minimum with that engine. This is half a tank less.

[UmbralRaptor]

I managed to badly mistake the design -- I thought it had 2 full tanks. :-[

I don\'t suppose that Kosmo-not\'s approach is acceptable? Same amount as tankage as what you\'re going for, though higher overall part count.

[Bluejayek]

The point is to do with as little as possible

Cutting out the decoupler and extra engine is better!

The idea of this is to top Kosmo\'s approach.

[UmbralRaptor]

We\'ll see -- gravity drag losses hurt this badly. Maybe if I have an initial Ap of more like 40 km...?

edit: I think a more continuous ascent profile is in order?

edit 2: I *think* reversing the tank order makes a difference here. Also, pitchover runs into some harsh issues. Too early, and aerodynamic drag kills you. Too late, and gravity drag does instead.

[The_Duck]

It\'s possible, in principle. I managed to get MechJeb to fly it into a 70km x 70km orbit after a few launches spent playing with the ascent profile. I eventually succeeded with a turn start altitude of 15km and a turn end altitude of 60km (and the default final pitch of 0 degrees, and the default turn shape).

(I left out the ASAS and used a radial MechJeb model, which is essentially weightless).

[grovest4life]

Can I submit my own design to the challenge or is only your ship allowed for this challenge? If the design is open I have a one and a half tank equivalent orbiter design that can reach orbit with a parachute on-board and enough fuel to de-orbit and land safely with a few sips of fuel to cushion the landing. Here is the photo album http://imgur.com/a/6pYxg. I did use Mechjeb since I\'m not to good at hand flying but I have included the mechjeb free version craft file. Name of craft is tentative yet though.

[Bluejayek]

Can I submit my own design to the challenge or is only your ship allowed for this challenge? If the design is open I have a one and a half tank equivalent orbiter design that can reach orbit with a parachute on-board and enough fuel to de-orbit and land safely with a few sips of fuel to cushion the landing. Here is the photo album http://imgur.com/a/6pYxg. I did use Mechjeb since I\'m not to good at hand flying but I have included the mechjeb free version craft file. Name of craft is tentative yet though.

Interesting design. Is there a reason for the stack decouples on the bottom?

As per allowed in the challenge, people are welcome to post their minimal designs. I\'m just trying to see what the absolute minimum is that can achieve orbit. On that criteria, the deisgn I posted seems to be the best (Since duck was able to orbit it), as it has 4 fewer parts then yours, and a takeoff mass of 2.2 less. That being said, yours is a MUCH more practical design, being able to deorbit and land safely. Very impressive.

[grovest4life]

The decouplers on the bottom are to fight the sticky pad bug I am dealing with they release the moment the engines fire other wise the ship acts like its glued to the pad.

[Romfarer]

I made orbit with apoapsis 118,321m and periapsis 74,689m. One FL-T250 tank and one FL-T500 tank + pod and the LV-909 engine of course. Having an ASAS module on any minimalistic challenge is a HUGE handicap and i never use that.

[Bluejayek]

I made orbit with apoapsis 118,321m and periapsis 74,689m. One FL-T250 tank and one FL-T500 tank + pod and the LV-909 engine of course. Having an ASAS module on any minimalistic challenge is a HUGE handicap and i never use that.

Screenshot? Also, what sort of ascent profile did you use? Very good job either way.

Also, as I stated, the ASAS is a modded one with 0.01 mass, so minimal handicap. Just used because I have issues doing small corrections without it on such a tiny craft.

edit 2: I *think* reversing the tank order makes a difference here.

Hmm. With halftank on top, once it is dry you are carrying 4.2 mass. With the fulltank on top at half dry, you are carrying 4.15 mass units. You are correct, it seems it would make a minor difference.

[VinnyMB25]

Challenge Accepted... 8)

[Romfarer]

Screenshot? Also, what sort of ascent profile did you use? Very good job either way.

What you dont believe me? I can do orbit with 13 SRB\'s 8)

As for ascent profile, i use the following method: Start with full burn, make sure to hit CAPSLOCK to enable your manual SAS. Somewhere between 13 and 14km start your 'curve'. Basically start tillting your craft (to the right) towards a 90 degrees vertical axis (HDG) and 0 degrees lateral axis. This is the heading you want you craft to be traveling at orbit, somewhere above 68km. To execute 'the curve' correctly and speed efficiently you want to always have the craft direction arrow inside the yellow circle (the heading your ship is actually traveling). This way you loose the least amount of speed. When you are at 40km height, you want your craft to be traveling at approximately 30 degrees lateral. Then comes the tricky part.

It is unlikely you will be traveling 0 degrees lateral at the point you hit 68km height. Therefore you have to cut your engines somewhere close to 68km. It is no point in using engines after 68km unless your picth is close to 0 degrees lateral. I usually drift at this point until the pitch of my craft is somewhere approximately 2-4 degrees lateral, then i make a full burn in the direction im traveling until the fuel is gone. At this point you want to have a speed close to or preferably above 2300ms.

NOTE: This is the same maneuver you use to stabilize your orbits: At apoapsis, speed up in the direction you are traveling to elevate your periapsis.

Sorry if i have stated the blatantly obvious...

[Bluejayek]

What you dont believe me? I can do orbit with 13 SRB\'s 8)

I definately believe you, but pictures are always nice! Preserve the flight for all time so future generations can stand in awe of your brave astronauts achievments while looking at the faded pictures in the Kerbsonian museum of aeronautics!

As for ascent profile, i use the following method: Start with full burn, make sure to hit CAPSLOCK to enable your manual SAS.

FACEPALM!

I did not know about precision mode.... This makes flying so much easier without an ASAS.... Thank you.... With this knowledge I chucked the modded ASAS module and flew this thing manually for the first time (More on that later)

Somewhere between 13 and 14km start your 'curve'. Basically start tillting your craft (to the right) towards a 90 degrees vertical axis (HDG) and 0 degrees lateral axis. This is the heading you want you craft to be traveling at orbit, somewhere above 68km. To execute 'the curve' correctly and speed efficiently you want to always have the craft direction arrow inside the yellow circle (the heading your ship is actually traveling). This way you loose the least amount of speed. When you are at 40km height, you want your craft to be traveling at approximately 30 degrees lateral. Then comes the tricky part.

It is unlikely you will be traveling 0 degrees lateral at the point you hit 68km height. Therefore you have to cut your engines somewhere close to 68km. It is no point in using engines after 68km unless your picth is close to 0 degrees lateral. I usually drift at this point until the pitch of my craft is somewhere approximately 2-4 degrees lateral, then i make a full burn in the direction im traveling until the fuel is gone. At this point you want to have a speed close to or preferably above 2300ms.

NOTE: This is the same maneuver you use to stabilize your orbits: At apoapsis, speed up in the direction you are traveling to elevate your periapsis.

Sorry if i have stated the blatantly obvious...

While some of what you have posted I knew already, it is all apreciated. More detail is better then less, as one can always skim through what they don\'t know. Thank you.

Using your tips, I flew this craft and managed to make it into a 281640m by 73430m stable orbit! One modification I made was to flip the order of the tanks as suggested by Umbral.

For my ascent profile, I started turnover a bit earlier then you did, around 8km. After this, I constantly turned over at 90 degrees, keeping pointed on the leftmost edge of the *GREEN* flight direction circle. After my apopsis bit around 50km, I flipped over completely horizontal and burned until it was over 70km. Then, I cut engines and waited until just before periapsis and burned the rest of my fuel.

Some pictures follow.

And we made it! Successful orbit! Too bad there\'s no return.

Further, I believe with this ascent profile done correctly, if I am more careful when I enter orbit to not raise my apoapsis above 70km, it will be possible to deorbit this craft, and MAYBE crashland with kerbals intact. I will get back to you on this.

[Bluejayek]

To update this thread: The challenge is now to successfully put this craft into orbit, complete at least one orbit, deorbit, and bring the kerbals safely back to earth. I am convinced it is possible. I managed to get into a ~70km orbit, complete an orbit, de-orbit by dropping my periapsis to ~50km and aerobraking, and have a small ammount of fuel left for \'landing\'. However, I balked on the landing and burnt my fuel too soon. With proper landing fuel use, this should be possible.

[Cooly568]

I tried this and got the apoapisis to 80 km and I didn\'t get a periapsis.

[Bluejayek]

Cooly, I recomend trying to turn over sooner. With this craft you really need a continuos turn starting from somewhere between 8k and 13k altitude. You should be fully turned over by the time your apoapsis reaches 50k, as it will keep rising on a horizontal burn. Even with this, you generally will have to bring your apoapsis to just above 70k, then wait until you are at apoapsis to burn to bring your periapsis out of atmosphere.

[Cooly568]

Cooly, I recomend trying to turn over sooner. With this craft you really need a continuos turn starting from somewhere between 8k and 13k altitude. You should be fully turned over by the time your apoapsis reaches 50k, as it will keep rising on a horizontal burn. Even with this, you generally will have to bring your apoapsis to just above 70k, then wait until you are at apoapsis to burn to bring your periapsis out of atmosphere.

I didn\'t use a ASAS so on launch I was all over the place. =P

[Romfarer]

*GREEN* flight direction circle.

Why is mine yellow?

I shall swap the order of the tanks. My crew are already experienced crash landers, however i doubt there will be enough fuel left. We will either need a parachute or some kind of big landing cushion to pull this off. ;D

[Romfarer]

Making orbit with the big tank on top makes it A LOT easier but as you can see from the scereenshot i have to make the orbit more fuel efficient to be able to land the craft.

So my plan for this is to use the standard procedure then when i am leveling out the periapsis, make it just above 68km so it will require minimal fuel to get it back to a declining orbit, then make gravity/atmosphere do the job. And finally use a maximum burn (the SRB method 8)) to land the craft.

I wonder how much fuel it will take.....

[Bluejayek]

This is still my closest attempt. As you can see, I managed to be extremely efficient with fuel, having that much left to land. However, I seriously botched the landing as I burned off my fuel at about 2000m rather then going \'SRB style\' as you say.

[Romfarer]

This is still my closest attempt. As you can see, I managed to be extremely efficient with fuel, having that much left to land. However, I seriously botched the landing as I burned off my fuel at about 2000m rather then going \'SRB style\' as you say.

Haha, it looks like all your kerbonauts have discovered the fuel gauge!

The way you describe this it sounds like you could only get one go at this, so i suspect this little tip may help: Hit F5 to save and F9 to load. Its even possible to save/load more games than the quicksaved ones by moving your sagegames/persistent files around...