48-7S fan club.

[magnemoe]

Does anybody else seriously love this lite inline engine?

As in it becomes you most used engine outside of the mainsail for boosters.

Only downside is the low trust but for small landers with seats and probes its more than enough and with its small size its easy to stack. You can use three small struts to get an radial placement.

I found it made lots of other engines obsolete in practice. very low weight, decent ISP for an so small engine. the 3rd highest TWR in the game, the radial version 24-77 has a bit lower weight 0.09 but far worse ISP.

The only remaining use for the 24-77 is on skycranes where you want an short burn to land something. If you do long burns use 48-7S on struts but the 24-77 works well if you want 4-6 of then and perhaps 4-500 m/s ISP to deorbit or land on Minus or final braking on places with atmosphere.

The ant win for very light probes and landers together with the oscar tank but if you need three oscar tanks and two radial ants or more replace the ants with an 48-7S.

The 909 looses out in any scenarios I have found, a bit better ISP but half the TWR squeezes it very hard between the 48-7S and the LV-N.

[RocketPilot573]

I use them on my VTOL...

The plane cannot hover on the 909s alone.

[SkyRender]

It's actually a bit of a misconception that the 48-7S is always a worse choice than the 909. For any sort of light-lander application, it blows the 909 out of the water and actually gets better efficiency while doing it. I highly recommend the 48-7S for any gravity level below 2m/s.

[Giggleplex777]

I think I under use that engine.

[magnemoe]

It's actually a bit of a misconception that the 48-7S is always a worse choice than the 909. For any sort of light-lander application, it blows the 909 out of the water and actually gets better efficiency while doing it. I highly recommend the 48-7S for any gravity level below 2m/s.

Correction the 909 is an better choice for standard heavy landers, the things with the two man lander can, 100 liter monoprop, 4 large landing legs and docking port, dry weight 3.6 ton.

With 180 liter fuel the 909 get 1442 m/s while the 48-7S get 1407 m/s, the 909 benefit will increase as we add more fuel, now the LV-N get 2225 m/s but is harder to build an lander around.

In short the 909 win the heavy lander competition, it also win with 90 liter fuel something who surprised me.

Now let us scale things down, one man lander can 50 liter monoprop and the medium landing legs dry weight 1.2 ton.

With 90 liter fuel the 48-7S get 1825 m/s, the 909 get 1672 m/s, with 270 liter fuel the 48-7S get 3524 m/s, the 909 get 3422 m/s

Scaling things even more down to probes or rover seats and the 48-7S win on walkover.

I managed to forget the heavy landers as I have worked on small stuff the last month and used a lot of 48-7S, one of the creation is an 8 ton Eve lander who can reach orbit from 6500 meter.

[Zeroignite]

I'm a recent 24-77s convert. Previously I'd used the radial 24-77 for small craft, but the stack version is kind of completely better. The only awkward thing is stock auto-fairings on decouplers being half-meter... good thing the procedural fairings mod has me covered

[SofusRud]

that engine seriously needs to be nerfed. I say it should have the same or similar ISP to the little radial red engines

[magnemoe]

that engine seriously needs to be nerfed. I say it should have the same or similar ISP to the little radial red engines

Might be but think that the red radial is underpowered,

ant isp: 290

24-77 isp : 300

48-7S isp : 350

909 isp : 390

The 20 kN engines is 13 times stronger than the ant, the 909 is 2.5 times stronger than them so they should be closer to the 909 than the ant and the 48-7S lays pretty much in the middle.

Only thing might be to increase the weight to 0.15 that would put it more evenly between the ant and the 909.

Might also be that radial engines should be weaker, look at the terrible mark 55. its very easy to just group 4-8 of an radial engine around an tank.

[bsalis]

I agree that the 48-7S is a bit OP.

It's wrong to compare it to the 24-77, because that is already a bit on the OP side itself.

[magnemoe]

I agree that the 48-7S is a bit OP.

It's wrong to compare it to the 24-77, because that is already a bit on the OP side itself.

The 24-77 has high TWR but poor ISP, however the only two measure points is the ant and the 909. Might say that the ant is to small to be efficient, you sacrifice isp to get an 30 kg engine.

Now increase the weight of the 48-7S to 0.13-0.15 ton and perhaps 0.18-0.2 ton for the 24-77 as it has to have the radial connector and I think it should fit right in.

[Tw1]

It's a great little engine for small landers, or Munar accent stages. Or retro thrusters, for small, fast adjustments. I used it a fair bit when it was in KSPX, and was happy it's now stock.

If they do decide to nerf it, I hope they don't do much. I recall some situation where I found I could get more delta V from the 24-77, but perhaps I'm not remembering right.

Knocking it down to an ISP of 330, or 340, maybe, shouldn't be too bad.

Personally, I'd prefer to loose ISP than gain weight, as it's useful as an auxiliary engine, and extra weight will effect the delta V and TWR of a whole ship, but reducing ISP means I'd just have to be more frugal with that engine.

[RoboRay]

I love the 48-7S, but the ISP is a little high... I had assumed that it would be brought into balance when it became a stock part, but it matches the stats it had as a KSPX mod part.

I use it for the ascent stage of my Apolloesque LM...

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...among many other applications I find for it.

[ComradeGoat]

I'm using this little engine a lot on my spaceplane shuttles. It's really light and does all you need to get from a barely orbital flight at 30,000 metres to orbit.

[lazarus1024]

The 48-7s is my current favorite engine for ascent stages for that various moons and minor planets.

Well, okay, it might not cut it (as one engine anyway) for Tylo, but it works great on the Mun, Minimus, Moho, Dres, etc.

[magnemoe]

The 48-7s is my current favorite engine for ascent stages for that various moons and minor planets.

Well, okay, it might not cut it (as one engine anyway) for Tylo, but it works great on the Mun, Minimus, Moho, Dres, etc.

One 48-7s Tylo lander. The seat to let you do warp, the two oscar tanks to balance, both are dropped before deorbit burn. I use an ladder to save 70 kg.

[M5000]

Yes, I do love it. It's a nice, compact little engine. Though, I haven't found too much use for it on full-size OTVs, the LV-909 will take the cake there, unless I'm to use a NERVA, which is totally overkill for a standard run-of-the-mill OTV. But I imagine the 48-7S could find its home quite properly on a small lander or single-man OTV. I'll skip it for the satellite application, as I almost always use ion engines in that respect. Though, maybe I'm missing out....

[SkyRender]

Yes, I do love it. It's a nice, compact little engine. Though, I haven't found too much use for it on full-size OTVs, the LV-909 will take the cake there, unless I'm to use a NERVA, which is totally overkill for a standard run-of-the-mill OTV. But I imagine the 48-7S could find its home quite properly on a small lander or single-man OTV. I'll skip it for the satellite application, as I almost always use ion engines in that respect. Though, maybe I'm missing out....

For any sort of long-haul application, it's pretty hard to beat ion or LV-N engines. The 48-7S is a lander engine, plain and simple, and it excels at this in any situation where the gravity is just too darn low to justify using 909s or LV-Ns. Minmus, Bop, Pol, and even Gilly are all top candidates for using a 48-7S for your lander's engine. Twin 48-7S engines can make landing a light enough load on the Mun, Dres, or Eeloo a snap too.

[tavert]

The numbers back up liking the 48-7S for many many uses: http://forum.kerbalspaceprogram.com/showthread.php/45155-Mass-optimal-engine-type-vs-delta-V-payload-and-min-TWR

The LV-909 is almost completely obsolete now. Handful of uses for it on the border between 48-7S and LV-N, that's it.

[Aqua667]

The 48-77 is my one of my favorite engines in the game. AMAZING TWR, low profile, looks great, and I like the sound it makes . Weighs only 4 tons, but can deliver a 1/5 ton payload into LKO!

[PotatoOverdose]

Its a good small engine for small payloads. For larger (>10-15t) payloads there are better engines.

The numbers back up liking the 48-7S for many many uses: http://forum.kerbalspaceprogram.com/showthread.php/45155-Mass-optimal-engine-type-vs-delta-V-payload-and-min-TWR

The LV-909 is almost completely obsolete now. Handful of uses for it on the border between 48-7S and LV-N, that's it.

I wouldn't go as far as to say that it is obsolete. There is probably a large area of overlap where the LV-909 is within 5% of optimal efficiency of the 48-7s. The problem with your graphs is that they don't really show you how close is the next runner up. Since a large vehicle will require a lot of 48-7s engines, the LV-909 will win out on part count in many cases which leads to better fps and performance for larger rockets, while only loosing a marginal amount of dV.

The situation is probably more inline with the LV-T30 and the aerospike, both of which are really close to one another in allround performance but occasionally outperform the other at a given task.

Personally I think the 48-7s just fills a gap in the stock parts for smaller in-line engines, which is a good thing.

Edited September 10, 2013 by PotatoOverdose

[tavert]

The LV-909 has only 2.5 times the thrust, so it won't be winning out on part count by all that much. Here's a version that limits the number of engines to 16: http://imgur.com/a/yuUH4

Didn't put in the low-TWR plots there, but the 909 won't gain a whole lot of ground just on part count. If you want to see a percentage that my optimal choice wins by over the next-best engine type at each point, that could be plotted.

All other things being exactly equal (so for two craft with the same delta-V, initial mass and TWR), it's actually better to use the engine with the lower Isp. That way your TWR will increase faster as you burn through the same amount of delta-V.

[Wayfare]

The 48-7S made the 0.21 version of the Munshine V possible. Its lighter weight and lower fuel requirement compared to a rack of 24-77s caused a trickle-down effect of mass reduction compared to the 0.20. This allowed a lighter CSM, which in turn allowed the use of a Skipper on the third stage because the second and first now had so much less payload mass to lift off of Kerbin's surface. The FL-T100 tanks helped a lot too, of course.

[PotatoOverdose]

The LV-909 has only 2.5 times the thrust, so it won't be winning out on part count by all that much. Here's a version that limits the number of engines to 16: http://imgur.com/a/yuUH4

Didn't put in the low-TWR plots there, but the 909 won't gain a whole lot of ground just on part count. If you want to see a percentage that my optimal choice wins by over the next-best engine type at each point, that could be plotted.

All other things being exactly equal (so for two craft with the same delta-V, initial mass and TWR), it's actually better to use the engine with the lower Isp. That way your TWR will increase faster as you burn through the same amount of delta-V.

Hmm, I didn't know that about lower ISP engines, learn something new every day. I would be interested in seeing just how much the 48-7s wins over the LV-909, if it isn't too much trouble to plot. I suspect it won't be that big of a difference, but I could be wrong.

[Kerbal01]

I use 4 of them attached around a 909 for 3-axis control of my Duna rovers transfer-braking stage,i love the little bugger.

[wilt57]

All other things being exactly equal (so for two craft with the same delta-V, initial mass and TWR), it's actually better to use the engine with the lower Isp. That way your TWR will increase faster as you burn through the same amount of delta-V.

I think the 48-7S is a great engine, it can lift a bigger lander off Minmus than many people could probably guess, but burning fuel for the purpose of reducing your mass thus raising your TWR seems like a waste. While I can't argue against what you said, if I use a more efficient engine I don't need to bring as much fuel in the first place, making my entire craft lighter along with any craft that propelled said craft previously, like a launcher.

I'm not a pro, but I can't think of a situation where I would want my TWR to increase over a burn. Maybe a dedicated landing stage that would be dropped before ascending back to orbit. Even then I think a better engineered lander using more efficient engines would require you to use less fuel to achieve the same goal.

My most efficient asparagus launchers have decreasing TWR as I stage. I use greater delta-V to reach orbit, but I use less fuel because I'm burning more efficient engines for a longer time. In the end, my long burns use less fuel than an inefficient engine that changes delta-V quickly. What am I missing here?