Rockomax 48-7S and LV-1 rebalancing

[NERVAfan]

I've seen the Rockomax 48-7S engine described as overpowered, and the TWR does seem very good...

I'd like to suggest that it if gets changed, the thrust should be lowered rather than raising the mass, since the only other in-line 0.625m engine (well, besides the ion) is the LV-1 "ant" engine, which is kind of useless. So the 48-7S IMO is a needed engine (for small landers on Mun and so on) even if overpowered. Maybe the Isp could be lowered a bit too?

For that matter, the LV-1 probably needs a bit of a boost. It has bad TWR and unimpressive Isp... it probably needs a slightly better vacuum Isp.

Just some thoughts....

[CaptRobau]

The LV-1 seems to get a boost in .24, according to the more recent Squadcast. Along with the Ion engine. Both are to make them more useful. Nothing about the Rockomax though.

[Supernovy]

I've found the LV-1 to be pretty well balanced considering its tiny mass. It's right between the 24-77 and ion engine in terms of TWR and Δv on comparable small probe designs. A higher I_sp with the same mass could lead it to being overpowered.

The mass ratio of xenon tanks is lower than LFO tanks, from what I've seen, so an Isp increase could lead to an ant with LFO giving more Δv and TWR than an ion engine with xenon on an otherwise identical probe.

I'm less negative on changing the LV-1's thrust, though. There seems to be a 1300% gap in thrust between the current LV-1 and 24-77, and an even larger percentage up to the next stack 0.625 metre engine, the 48-7S. The LV-1 is 300% the ion's thrust, which gives you an idea of the disparity in probe-size engines. As it seems the LV-1 is being changed in the next update, we'll just have to wait and see.

On the other hand, the 48-7S is definitely overpowered. My idea for new stats for it would be 20kN thrust, 250s-300s I_sp and 0.066T mass, to keep it at its current TWR. This gives it a slight benefit over the 24-77, but not a huge one.

I'm perfectly happy with some parts being strictly better than others so long as they're later on in the tech tree, however.

[NERVAfan]

I've found the LV-1 to be pretty well balanced considering its tiny mass. It's right between the 24-77 and ion engine in terms of TWR and ÃŽâ€v on comparable small probe designs. A higher I_sp with the same mass could lead it to being overpowered.

According to the wiki, LV-1 is 290 s vacuum Isp, 24-77 is 300 s. Has that changed?

The mass ratio of xenon tanks is lower than LFO tanks, from what I've seen, so an Isp increase could lead to an ant with LFO giving more ÃŽâ€v and TWR than an ion engine with xenon on an otherwise identical probe.

Xenon tanks do have a worse mass ratio, but I'd be surprised if it made up for 290 s vs. 4000 s specific impulse.

On the other hand, the 48-7S is definitely overpowered. My idea for new stats for it would be 20kN thrust, 250s-300s I_sp and 0.066T mass, to keep it at its current TWR. This gives it a slight benefit over the 24-77, but not a huge one.

I'd rather keep the Isp and drop the TWR a lot. You don't need that much TWR to land on Mun (or most airless bodies) and the 48-7S IMO doesn't really need to be a great ascent-from-Kerbin engine.

[UmbralRaptor]

According to the wiki, LV-1 is 290 s vacuum Isp, 24-77 is 300 s. Has that changed?

It's still the same, but the LV-1 is notably lighter. If TWR isn't a notable issue, the LV-1 is surprisingly good for low mass rockets.