Bulky and unruly payloads

[Kerr_]

So i think i'd like to make some mun/minmus bases that look like... well... bases, rather than landed ships. that would mean: large, awkward, bulky.

Any suggestions on how to lift these in the new aero?

[n0xiety]

Firstly if you don't want to go 20km straight up then start your gravity turn which will cost you alot of dV you need mechjeb. In the new version of mechjeb you can set the AoA limit degree which prevents flips. It limits your angle of attack against your prograde so lets say you set it to 3 degrees it won't turn the rocket more then 3 degrees infront of the prograde untill the prograde catches up. This is just not humanly possible so you do need mechjeb. I recommend 3 degrees AoA.

Another trick you can use is to have a fairing at the bottom and at the top of the payload and connect the bottom one to the top inverted one. I carry big payloads at the middle of the rocket using this and they are always stable. You can use this however bulky your payload might be. It will just cause more drag as you make it wider tho.

[SlabGizor117]

Yeah, fairings are the way to go. As far as getting them to the Mun or Minmus, I've found what helps me is to make one part and kinda "step back and take a look". With most medium 2.5m size things, something I would expect a base to be made out of, I've found that a half size 2.5m tank(half of an orange tank) and a skipper has plenty of Delta-V, and more than enough TWR to get the burn done reasonably fast. Then, I would make a fairing around it, and now you step back again and say, "I need to get this to Low Kerbin Orbit. What's the best way to do that without overengineering my rocket?" For rockets this size, I usually use a Delta-IV Heavy style of rocket, with a bunch of orange tanks and mainsails. Normally I asparagus stage the radial boosters, and it works really well for me.

Have fun!

-Slab

[Kerr_]

Let me define bulky.

[EtherDragon]

I would say that definitely meets the standard for bulky and unruly.

[Kerr_]

and fairings dont work very well

[Jonboy]

Firstly if you don't want to go 20km straight up then start your gravity turn which will cost you alot of dV you need mechjeb. In the new version of mechjeb you can set the AoA limit degree which prevents flips. It limits your angle of attack against your prograde so lets say you set it to 3 degrees it won't turn the rocket more then 3 degrees infront of the prograde untill the prograde catches up. This is just not humanly possible so you do need mechjeb. I recommend 3 degrees AoA.

Another trick you can use is to have a fairing at the bottom and at the top of the payload and connect the bottom one to the top inverted one. I carry big payloads at the middle of the rocket using this and they are always stable. You can use this however bulky your payload might be. It will just cause more drag as you make it wider tho.

It's definitely humanly possible. You don't "need" mechjeb. Mechjeb might make it easier though.

[Mister Dilsby]

You may find some good ideas over here.

[worir4]

You could try split up the payload or another alternative is to use multiple rockets for the same payload. An example is on that base in the image above you can use four rockets on each side of the rocket. This makes it easier to lift and also the fairings don't look so strange. Don't forget struts!

[Kerr_]

I'm more interested in the idea of getting something ridiculous like that to minmus, than designing a practical base. Also I want to do it stock.

I cant put this piece back together, unless i want a hundred clampotron minis

[Requia]

Firstly if you don't want to go 20km straight up then start your gravity turn which will cost you alot of dV you need mechjeb. In the new version of mechjeb you can set the AoA limit degree which prevents flips. It limits your angle of attack against your prograde so lets say you set it to 3 degrees it won't turn the rocket more then 3 degrees infront of the prograde untill the prograde catches up. This is just not humanly possible so you do need mechjeb. I recommend 3 degrees AoA.

Another trick you can use is to have a fairing at the bottom and at the top of the payload and connect the bottom one to the top inverted one. I carry big payloads at the middle of the rocket using this and they are always stable. You can use this however bulky your payload might be. It will just cause more drag as you make it wider tho.

Or you can make a ~10 degree turn (exact amount varies by craft) at 30m/s then just kill sas and let the forces at play work for instead of against you.

[n0xiety]

It's definitely humanly possible. You don't "need" mechjeb. Mechjeb might make it easier though.

Sorry but some of my rockets are so unruly and bulky that it literally isn't humanly possible to do a gravity turn starting at 3km... I use mechjeb with 1 degree AoA on those unusual rockets and it barely saves it. If it goes up to 3 degrees whoops rocket suddenly starts flipping all around. And with the not so smooth keyboard controlls small hits means more than 3 degree turn and flip as always.

[Requia]

Sorry but some of my rockets are so unruly and bulky that it literally isn't humanly possible to do a gravity turn starting at 3km... I use mechjeb with 1 degree AoA on those unusual rockets and it barely saves it. If it goes up to 3 degrees whoops rocket suddenly starts flipping all around. And with the not so smooth keyboard controlls small hits means more than 3 degree turn and flip as always.

Your problem is you're trying to do the work. You need to let gravity do the work for you, tilt yourself just a bit off the launchpad and gravity slowly tips the rocket over. I put this thing in orbit in one piece without fairings, at supersonic, manually: http://imgur.com/MT4O6BC

[n0xiety]

Your problem is you're trying to do the work. You need to let gravity do the work for you, tilt yourself just a bit off the launchpad and gravity slowly tips the rocket over. I put this thing in orbit in one piece without fairings, at supersonic, manually: http://imgur.com/MT4O6BC

You know what you got there is a perfectly symetrical lander which should be easy for me to get up there even with its bulky appearance. Im talking about payloads that are not symetrical and that pulls the rocket towards one side and flip. Here is my minmus operation:

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What you see here is a Fuel refinary and a science jeep with basicly 50000dV and can go anywhere fast on minmus. Collected all the science in 30 minutes and visited atleast 20 sites for crew reports which was my mission. (I know 50k was a bit op. Ended up using 15k for everything on Minmus) The Lander works as a refueling station for the 4 ion engines at the bottom of the jeep + its the way back home leaving the jeep at minmus. As you can see the minmus bus is not symetrycal and this causes alot of problems when i try leaving the turn to gravity itself. I have to force it to stay straight because of the uneven drag forces. Could i have built a rocket that is balanced with the Bus? Ofcource i could. But that would take alot of trial and error and maybe 5 times more time which i just don't want to spend for a refinary operation. So mechjeb provides me with the easy solution to this = Precision which is humanly impossible. I can give you the craft file and i bet you won't be able to make orbit with that bus without changing the design or going straight up till you reach 25km then start turning.

Edited May 21, 2015 by n0xiety

[Dilli]

I have put something similar on the minus. Went straight up till 25km-30km, then slowly turned to about 45 degrees and kept burning till apotosis was about 100km;

Low TWR (~1.2-1.4) until in orbit helps as does keeping speed low (~250m/s) until about 15km up then gradually increase thrust helps prevent flipping and wobbling.

Strutting everything well then liberally add delta wings to the bottom of the launcher to keep it going straight.

Troubleshooting - if it wobbles or tips below 25km while going straight up strut where there is obvious flex in the rocket and/or try go a bit slower.

- If wobbles / flexes also try limiting or disabling gimble on the launcher engines and disabling reaction wheels on the load (on mine only the center engine had gimble enable but limited to 50%) and/or adding a probe core further down the rocket to a part of the launcher and controlling the launch from there.

- If SAS cant hold it on course going straight up add bigger / more wings to the bottom of the launcher and/or strut obvious flex in the rocket.

[Requia]

If it's balanced enough to hold it off center it's balanced enough to point at prograde with built in SAS. The point is you never ever need to point anywhere but prograde while going faster than 30m/s.

[delabu]

I have the problem that I want to put bulky loads into orbit using a re-usable bottom stage. So, the bottom stage cannot have fins as it enters rockets first during re-entry so that I can give it a nice braking punch to stop the thing from burning out. So it needs to re-enter tail first. I need to unlock those fairings, though...

[Sharpy]

Your problem is you're trying to do the work. You need to let gravity do the work for you, tilt yourself just a bit off the launchpad and gravity slowly tips the rocket over. I put this thing in orbit in one piece without fairings, at supersonic, manually: http://imgur.com/MT4O6BC

That's a happy illusion with balanced, tight loads like yours.

The bottom one (power tower) required about twice its own weight in struts attached to decouplers to make it to the orbit in one piece. Once strutted properly it allowed for schoolbook gravity turn.

The top one - I couldn't get it to do a gravity turn - I couldn't even get it to fly straight up! At 400m/s it would flip if it strayed one degree from prograde. I overcame it with a pinecone nose - a nose cone thickly lined with Vernor engines.

And this one would perfectly follow a gravity turn, except - as normally - the nose wouldn't point exactly prograde. Which resulted in dumped stages to crash into the main hull or rip the drills off. The ascent had to be done with SAS on, set to prograde.

By the way, ever tried to bring a standard-sized airplane into orbit as a rocket payload? Good luck with your "let gravity do the work for you".

- - - Updated - - -

If it's balanced enough to hold it off center it's balanced enough to point at prograde with built in SAS. The point is you never ever need to point anywhere but prograde while going faster than 30m/s.

If you don't care about your orbit inclination. Rockets often stray off the 90 degrees course.

If you don't really care about the gravity turn being optimal. You can end up anywhere between flying horizontally at 25km and aiming 30 degrees from vertical with 80km periapsis, all depending on your payload's lift/drag profile.

[Sharpy]

Delabu: Find Warzouz's SSTO Cygnus rockets. They are SSTO, they have fins, and they have zero problems reentering tail first and braking using their engines. I don't quite know just how that works, but it works, and works well.

edit: oh, I realized I know how that works. Airbrakes near the top of the rocket. They provide just enough drag to keep it stabilized tail-first.