Beast won't turn - Boosters (Answered. Kind of)

[Tokay Gris]

You should try tilting the rocket 5 degrees to the east on the launchpad. Secure it with launch clamps. Report back with results.

It would possibly make the ascent a bit better, but not much. I would still be at about 15.000 with those 5 degrees.

[ratchet freak]

It would possibly make the ascent a bit better, but not much. I would still be at about 15.000 with those 5 degrees.

no because the thrust will be going through the COM but grav force will not be parallel to it which will turn the rocket (you know like a gravity assisted turn aka a gravity turn)

[Tokay Gris]

no because the thrust will be going through the COM but grav force will not be parallel to it which will turn the rocket (you know like a gravity assisted turn aka a gravity turn)

Haven't tried that yet, BUT:

By switching on a gimbaled engine during ascent I managed to get the rocket to turn. But once I switch it off (basically switching "limit to terminal velocity" in MechJeb on and off), it straightened again.

There seems to be a tendency of boosters to go straight up. Not quite sure why yet.

Will try that tomorrow. But my guess is that those 5 degrees from launch will stay 5 degrees during ascent at best.

[Tokay Gris]

Oh, and a quick update. I changed the design a bit (still have 12 nuclears), can now make orbit easily with enough delta-V left to land on Mün or Minimus AND achieved this for only 300.000 instead of the 400.000 the problematic launch took. Will post a picture tomorrow.

EDIT: And it also looks better... And I managed to design it in a way so that really all engines fire at launch. First tests showed some flaws (such as way too few RCS ports to allow for docking, when the vessel is full), but were promising.

Edited October 2, 2014 by Tokay Gris

[Tokay Gris]

if you have only eight of them wrapped around the tank, you can place decouplers below and needn't worry about the fairings getting stuck

Tried that. Didn't work. The fairings got stuck between the engines and the tank. But solved that with actually putting the boosters laterally. It looks kind of cool, I must say....

[Ruedii]

OK, Canards on the nose of a rocket can add a LOT of torque. Just make sure their lift is countered by fins in the back.

Also, remember, the further the RCS ports are from the center of gravity the more effective they are.

Finally, reaction wheels are useless without electricity to power them, remember, boosters don't generate electricity, so if you don't have enough electricity, you can't control a rocket with reaction wheels. Likewise, if you use a probe core, you run into a worse problem, all controls freeze once you are out of battery.

[Laie]

Tried that. Didn't work. The fairings got stuck between the engines and the tank. But solved that with actually putting the boosters laterally. It looks kind of cool, I must say....

Tried that too. It works if you pay attention to the seams in the fairings. Rotate LV-N by 90 degrees.

Though I have to admit that it bugs me if the red nose doesn't face outward. And if the lateral mount even looks better... why not?

[StrandedonEarth]

Finally, reaction wheels are useless without electricity to power them, remember, boosters don't generate electricity, so if you don't have enough electricity, you can't control a rocket with reaction wheels. Likewise, if you use a probe core, you run into a worse problem, all controls freeze once you are out of battery.

This. No power means no control. Make sure you have a big battery on there somewhere, and/or an RTG to keep it powered up.

[dbmorpher]

One thing about srb's they don't produce ec when activated so you will need a power source like they said.

With these new funds I too have been using srb's due to their frugality. I think the problem with your design is that the TWR is too high. If you use vessel info on MJ you cand find the TWR on launch. If you use throttle control on your srb's they will burn longer and be more controllable.

I also agree with pecan on the use of nuclear boosters. They just aren't worth their weight or price.

[Tokay Gris]

Trust me: It isn't energy. Couple of thousand units.

[Fyzzi]

Sometimes I run into similar problems... I figured it's caused a bit by micro-oscilations due to the too low amount of struts... it simply wobbles just a bit and because it's that many parts that wobble each in other direction, it keeps you moreless straight BUT almost uncontrollable...

(happened to me, but doesn't mean it's what's causing your problem, but when it comes to me - worth a try) hope it helps...

[Hannu]

Did you try my type of solution? What was wrong with that? I use much cheap boosters at first stages and have no special problems (after learning cycle at start of new version). One large SAS-unit can steer 3-6 largest boosters depending on configuration.

[dbmorpher]

If you could post a craft file we could edit it.

The file in in your saves folder.

[Tokay Gris]

If you could post a craft file we could edit it.

The file in in your saves folder.

Thanks, but no.

First of all, I kind of solved the problem. And am currently in the process of build a lifter like Pecans. First tests looked promising.

Secondly, I prefer to build my rockets myself. I really like tips and tricks, input and criticism, but not "We edit it for you". Thanks again for the offer.

[Tokay Gris]

This is a 100t SSTO launch-vehicle, fully recoverable with drogue & powered landing.

(That's 4 KR-2Ls)

Tried to recreate that vessel. Once I understood what you meant...

BUT: Even without payload (and just counting the tanks you had on that vessel) with four KR-2Ls I get a TWR on the launch pad of 1,59. Enough delta-V to get that vessel into orbit and back. But not with a payload...

If I attach a payload, TWR drops to 1.36. (roughly 100 tons)

So... first test:

Payload 108 tons (one orange and four tin cans). TWR on the pad: 1,36. Turning at apogee was a hassle. Got to orbit. Kind of. But empty. Last drops of fuel to get there.

But I like the idea of a lifter that can get back to Kerbin.

Would you mind posting the .craft? Not to use it, just so I can see what you did there.

[Tokay Gris]

Couldn't let go.

So I build a SSTO with lifting capacity.

Looks like this:

This test, however, showed that 120 tons (and change) was too much.

This stage gets 100 tons to orbit and is (like Pecans) fully recoverable.

What this boils down to is that I can get 100 tons to LKO for about 64.000 creds.

However, I ran into a rather funny problem:

This lifter is apparently so maneuverable that MechJeb lands it right on the launchpad. During testing, I repeatedly botched the landing, because I collided with the stability enhancers.

Well, a couple of tests later, this baby works pretty well, I must say.

P.S.: Anyone know why the colors of the tanks don't exactly fit? Doesn't look like a five degree mismatch.

Edited October 4, 2014 by Tokay Gris

[Kryxal]

It might be worth recovering the LSEs before you land it, then ... or land on the runway instead!