Launching light payload in FAR (the budget way)

[Mipe]

I have this problem... I've made a light probe thingy, weighing total 1.5 tons (with insertion fuel and engines). However, for the life of my goldfish I can't figure out budget-efficient (using Mission Control Extended and in debt) lift rocket. Using smallest fuel tanks and rockets I can achieve the necessary delta-v, however once the fuel is half way gone (or I drop a burnt-out stage), the CoM shifts up and the rocket begins tipping over.

When I try the bigger and heavier fuel containers and engines, not only do the costs rise, but so does the Delta-V... And as soon as the fuel tank is emptied out, the rocket again tips over.

I imagine this is because of the shifting CoM and top-heavy payload as well as due to ascent drag (using porcedural fairings for the nosecone).

I am at the end of my wits, so here I am turning to you great sages. How would you lift a small and light payload in a cost and fuel efficient manner?

[Motokid600]

I use FAR and MCE as well. I find small, light rockets are more susceptible to the aerodynamics and flip easily after second stage ignition. I simply put small wings on the second stage and it flies straight as an arrow. I use MJ which tends to over compensate in the upper atmosphere, but with fins on the upper stage its as stable as can be. As far as budget builds go.. Solid rocket boosters my friend. My light lifters consist of a solid fuel first and second stage with the third stage being liquid fuel for orbital manouvers. Also make sure you work to unlock MCE 's research. Also remember that it's not just your shifting CoM, but your TWR rises as well. Make sure you don't leave the pad with anything higher then a 1.5 TWR. ( 1.5 keeps gravity at bay. And I use a lower 1.3 for the upper stage. Then even lower for the third until about 60km where I'll put the hammer down )

Edited April 25, 2014 by Motokid600

[Mipe]

Small wings? I don't think I have those yet... But I'll consider adding what I have to the second stage as well. Any other tips?

[Motokid600]

What parts are you using? Stock? If so it may be more challenging. Other then that id say make sure you start your gravity turn really early at about 200-300 meters. Get that vertical speed up as much as possible as soon as possible this way there isn't too much turning needed in the upper atmosphere when your really moving fast.

Now im not sure what your using in terms of mods. I use alot. Im really early in the tech tree like you, but my set of parts will be much different then yours. But for what it counts heres a pic of my cheap duel stage SRB rocket. Believe it or not this rocket carries a land and return payload to the Mun and its under $50k with all the MCE research unlocked. ( which is why im barely into the tech tree ive been dumping all my science into MCE )

Post a pic of your rocket if your still having trouble ill help ya work it out.

Edited April 25, 2014 by Motokid600

[Hodo]

With FAR you should ideally start your gravity turn MUCH sooner than stock. I no longer play with a stock sized Kerbin but instead with the Realism Overhaul, and the way I managed to get my light weight communications satellites into orbit of 500km x 500km was starting the gravity turn as soon as I hit 1000m altitude or 180m/s. But I also use an Ares style rocket with a long SRB first stage. But you want to make sure your TWR should ideally be between 1.2-1.5, and if you are able use fairings around your cargo to reduce the drag on the front of your rocket. Your second stage should be about the same as your first stage for TWR, if not a bit less, I usually get away with .9-1.2 TWR. But my second stage doesn't kick in till well past 60km altitude on Earth.

[federally]

With FAR I suggest getting Procedural Fairings to shield those payloads. It makes liftoffs much easier

[Mipe]

Well, the reason I got FAR was to make those procedural fairings actually reduce drag of the rocket. I've used NovaPunch for a bit, disabled it to figure out how to launch stuff with stock. Thing with procedural fairing is that they ADD to the weight of payload... with a light payload, that's a lot. And the light payload is very very easy to lift... too easy, I find. Doesn't take much fuel, so I don't take too much fuel, however once fuel is used, the balance tips over rather quickly.

Ugh, this is giving me grey hair! Procedural fairings make things easier, but FAR makes it a pain.

Maybe I should play stock a while more to build up some more mileage...