Space shuttle with TWR of 1.02

[Saltless Lemons]

I built a space shuttle modeled after the real ones, and it turned out pretty good, perfectly balanced and everything. There's one problem. I have a thrust-to-weight ratio of 1.02. It just hovers there, above the launchpad, not tipping or anything, just very slightly drifting forwards.Is there any way I can bring my TWR up to a decent number without messing up the centers of mass/thrust? Or will I have to completely restart?Thanks for the help,Luke

Edited October 23, 2015 by Saltless Lemons

[FlipNascar]

Moar boosters. You don't need to restart, but you will need to rejig. Without pictures it's hard to give specific advice that relates to your launcher... I'll assume you're using a Shuttle-system in that you have a large main fuel tank, SRBs and the Shuttle attached to that... Just add some more SRBs until you get enough TWR. You can easily offset the SRBs into each other so that they don't look so ungainly. Yes, you may then need to rejig the Orbiter's positioning and the such, but it'll be a case of tweaking rather than a from scratch redesign.

[Venusgate]

I would d/l and use the Procedural Parts mod and change your stock boosters in to procedural boosters. With procedural boosters, you can modify the thrust of the boosters (at the cost of higher fuel consumption/sec) but you should be able to get the exact size you need.

[The_Rocketeer]

Bigger engines/more engines or less mass. That's kinda what a Thrust-to-Weight-Ratio is made of.

Either will probably mean re-balancing your CoT/CoM.

However, if you haven't got into an ascent, it's likely you haven't encountered the problems associated with shifting CoM yet anyway - I don't mean to be discouraging, but STS-replicas are hard mainly because of this.

[Saltless Lemons]

I managed to get it to 1.12 by dropping a bit (lot) of fuel, and surprisingly that didn't mess with the balance. I'll try adding more boosters, and see what I can do. Thanks for the help!

[AlextheBodacious]

so... it's answered...

[rotisserie919]

First off, 1.0 TWR is essentially hovering in place. You must pay the gravity well toll of 1.0 for a given SOI body, anything after that will go towards accelerating. In your case, your extra 0.02 TWR * Gravity of Kerbin@sea level is the equivalence delta-v of just under 10 cm/s^2, or about a light stroll in a vertical direction if you're lucky enough to stay straight.

That means you're paying the toll but aren't thrusting enough to benefit from it. You need more boosters.

Id set aside your SRBs temporarily and augment your main engines until they slightly exceed the 1.0 TWR by themselves for your shuttle with a maximum test payload. This will allow your shuttle to cruise on whatever acceleration your SRBs provide at launch with just enough excess throttle to make course corrections as needed while burning efficiently during ascent.

Now add your SRB stage and you should see your TWR climb nicely. If it is a significant TWR hike, you can then save fuel by throttling down your mains to save fuel then re-throttle them during SRB separation. Or if you want to extend your SRB burn, you can throttle them down and they burn slower to help safely push through the thicker lower atmosphere at safer speeds.

I, personally, am a fan of liquid boosters that I also feed their fuel into the main tank so when the boosters are spent, they leave the main fuel tank full after first stage separation. Hope these thoughts help. Homer->Mobile:D

[Saltless Lemons]

Okay, thanks for the info, it helps a lot!

- - - Updated - - -

Yeah, I was doing this on my phone and forgot to change the status. It's fixed now.