Did 1. 0 nerf SRB's too much?

[Bev7787]

SRBs are cheap and work better for me in early career in launching satellites to explore the Kerbin system

[SRV Ron]

My Minotaur 5 probe can no longer reach Duna let alone orbit Mun under 1.02.

[inigma]

Composite SRB made for a space shuttle, 24 all stock parts. Works beautifully!

See my sig for shuttle.

Edited May 14, 2015 by inigma

[inigma]

'nother SRB pic, this time showing you how they work

Beautiful? Functional? You bet! (craft file editing at its best - for the advanced engineer inside all of us)

all stock parts.

[zarakon]

'nother SRB pic, this time showing you how they work

Hmmm, it really doesn't show that. They still look like stacks of liquid fuel tanks.

[inigma]

Sorry, try this:

Each SRB is made of 8 stock boosters connected to the second from the top tank, strapped by 8 struts to the bottom clipped tank. All liquid tanks are empty of course, as they simply act as shrouds.

Then to the craft file itself to edit the solid booster amounts for each booster from 2500 units to 3750, to account for the extra/empty space above in the top two empty liquid tanks. It's not cheating since the individual solid boosters would contain that amount anyways if they were as long as these boosters appear, that and the extra mass is factored automatically into the game physics. Totally stock.

Edited May 14, 2015 by inigma

[Frostiken]

Besides reading stats have you actually played the game in 1.0? Because to my understanding and from actually played, they did some major modifications to the physiques engine and how ISP works in vacuum. Some of the stats have gone down but they actually perform better/more efficiently/different than previous when in a vacuum.

So far, SRBs to me feel buffed if anything with the new atmospheric changes. A single SRB takes me all the way into space and then some beyond 200km out! The LVT-45 also feels more fuel-efficient now in space, a lot of the engines do actually. I suggest you just try some of them out and see how it actually "feels" in the game besides what the stats say.

The problem is that SRBs are typically radially-mounted, and the drag changes mean that basically SRBs have undergone a net *nerf*.

The Thud radial LFE has the same problem - it was okay before, but with the new drag profile, it's barely as aerodynamic as a radial fuel tank with the lousy nosecones on it (despite being much smaller) so ultimately the engine is slightly worse in 1.0 than it was in .9.

[Tankbuster32]

I'm a little late to this post, but I have found something. Not only have the SRBs been nerfed into oblivion, but an SRB-based rocket is larger (which makes no sense, as solid fuels are supposed to be more dense than liquid ones) and more expensive (makes no sense, solid fuels are supposed to be cheap) than a liquid-propellant rocket with the same performance. The reason for the SRBs being so terrible is probably their abysmally low specific impluses which are not much better than sugar-based rockets in reality. Even the RCS thrusters, which I believe to be cold-gas thrusters, outdo the SRBs in terms of isp.

A fix for this: improve the isp of the rocket engines so that they sit more in the 200-250s range.

[WafflesToo]

I've run several cost-analysis' on payloads ranging from 1t to 10t and SRB cost between 1-1/2x and 2x as much for the same amount of dV as a LFO engine. They were dirt-cheap in 0.9 which off-set all of their disadvantages; they have no advantages in 1.0.x that I can tell.

[mythbusters844]

This is from another thread:

I definitely prefer the new liquid engines, if only because Squad is finally using realistic Isp numbers. The engines are all right in a believable range for LOX/kerosene or NTO/UDMH rockets, which makes balancing mod parts much easier.

But they really need to do something about solids. They were always worse than they should have been, but they hardly even have a purpose now. You can buy model rocket engines with better Isp.

Kerbal liquid engines vs. some close real-life matches:

| Engine                    | Thrust  | Mass   | Sea Isp | Vac Isp |
| ------------------------  | ------- | ------ | ------- | ------- |
| LVT-30 Reliant            | 215 kN  | 1.25 t | 280 s   | 300 s   |
| LVT-45 Swivel             | 200 kN  | 1.50 t | 270 s   | 320 s   |
| RD-0110 (Soyuz)           | 298 kN  | 0.40 t | ~260 s  | 326 s   |
| ------------------------  | ------- | ------ | ------- | ------- |
| RE-M3 Mainsail            | 1500 kN | 6.0 t  | 285 s   | 310 s   |
| RD-275M (Proton)          | 1833 kN | 1.26 t | 285 s   | 317 s   |
| ------------------------  | ------- | ------ | ------- | ------- |
| LV-909 Terrier            | 60 kN   | 500 kg | 85 s    | 345 s   |
| SpaceX Kestrel (Falcon 1) | 30 kN   | 52 kg  | --      | 320 s   |
| SpaceX Merlin 1D Vac      | 800 kN  | 500 kg | --      | 340 s   |

In general, Kerbal liquid engines (like all the other parts) are super-dense to balance them against the tiny, super-dense planet. That's fine.

It's actually hard to find anything comparable to the LV-909, because most real-life rockets in that thrust class are solids. The Poodle and Terrier are similar enough to LOX/methane rockets that one might conceivably build for Mars Direct, though, so I have no problem with them.

My only complaint is that the Isp numbers on the LVT-30 and LVT-45 are backwards. The LVT-30 clearly has the bigger vacuum nozzle, and should make more thrust because of that, and yet the LVT-45 has lower sea level and higher vacuum Isp.

Kerbal solid engines vs. stuff in the ATK catalogue:

| Motor                   | Thrust   | Mass    | Burn Time | Isp   |
| -----------             | ------   | ------- | --------- | ----- |
| RT-5 Flea               | 192 kN   | 1.2 t   | 5.7 s     | 150 s |
| RT-10 Hammer            | 227 kN   | 3.0 t   | 15.7 s    | 162 s |
| Orion 38 (Various)      | 32.7 kN  | 872 kg  | 71 s      | 287 s |
| Orion 50 (Pegasus)      | 115 kN   | 3.35 t  | 75 s      | 290 s |
| -----------             | ------   | ------- | --------- | ----- |
| BACC Thumper            | 300 kN   | 6.0 t   | 26.5 s    | 180 s |
| Orion 50XL (Pegasus XL) | 158 kN   | 4.3 t   | 71 s      | 291 s |
| Orion 50S (Pegasus)     | 467 kN   | 13.4 t  | 75 s      | 292 s |
| -----------             | ------   | ------- | --------- | ----- |
| S1 SRB-KD25k Kickback   | 670 kN   | 23.25 t | 52.1 s    | 190 s |
| Orion 50S XLG (GMD OBV) | 583 kN   | 16.11 t | 69 s      | 272 s |
| RSRM (Shuttle)          | 10811 kN | 569.4 t | 122 s     | 268 s |
| -----------             | ------   | ------- | --------- | ----- |
| Sepratron I             | 18 kN    | 72.5 kg | 5.0 s     | 154 s |
| STAR 5CB (Titan IV)     | 2 kN     | 2.4 kg  | 2.7 s     | 256 s |
| STAR 8 (MER)            | 7.5 kN   | 5.1 kg  | 4.3 s     | 273 s |
| STAR 17 (Delta/Atlas)   | 10.9 kN  | 79 kg   | 17.6 s    | 286 s |
| Estes E-30              | 33 N     | 45 g    | 1.0 s     | 189 s |

Solids are balanced completely differently from liquids. Kerbal solid rocket motors have similar masses to real-life solids, but they have laughable specific impulse. That's probably a decent balance trade-off for first-stage boosters, but it makes solids completely useless for anything else. If you have to lift it, you need better Isp than 150 s.

The thrusts are somewhat higher than real-life solids of the same size, but the real-life ones are engineered with specific grain patterns to keep thrust down. We have tweakables for thrust, so I have no complaints there.

The Orion 50 series are 50 inch diameter (1.275 m) solid rockets, so are pretty closely comparable. The Pegasus is an air-launched vehicle, though, so the motors have oversized nozzles. The ground-launched versions have an effective Isp around 270 s.

The Kickback is half-again as long as the ORION 50S XL, and taking that into account it's a very realistic thrust and weight. The Isp just sucks.

The STAR 5CB is a real-life stage separation motor. It's puny. A trio of STAR 8s each were used as the landing motors for Sprit and Opportunity. The STAR 17 is an old apogee kick motor that weighs as much as our sepratron. The Estes E-30 is a $16 model-rocket motor. Even the Estes motor has better Isp than the Sepratron. Heck, it has better Isp than any Kerbal solid rocket motor bar the Kickback.

I honestly don't think that a model rocket engine should have a higher specific impulse than an aerospace-grade rocket booster, no matter how "kerbal" it is. SRBs should also have a definite cost advantage over liquid engines.

Edited May 20, 2015 by mythbusters844

[Hannu]

I like nerfed SRBs. In 0.90 they were far too overpowered and practically free. I made often first stage from only SRBs (sometimes 40 largest SRBs) and it gave over 2000 m/s. Now they are much better. Liquid engines gives most dv and strong SRBs only help to lift stage few kilometers so that main engine gets near full thrust.