[Pre-1.9] So what's the point of Skiff?

[Jestersage]

With the 1.9 Skiff revamp -- and nice looking graphics -- I am curious what is the point of Skiff.

Skiff comes in two variants: 2.5m with 2.5 shroud, and the 1.25m mount with 1.875 shroud. Its current performance, in mass, a bit more than half of Skipper, while its thrust is a less than half a skipper. (so if one use 2x skiff, total mass is 3.2t, with thrust at 482/600 kn; comapre to skip's 3.0t, 568.75/650 kn). ISP is comparative identical, and once mounted to a stage it really make minimal difference if you need that amount of thrust (and typically you do, as it is a upper stage engine)

So would someone provide a good reason to use 2x skiff instead of 1x skipper in 1.9 (namely bare variant), aside from looks?

Edited January 23, 2020 by Jestersage

[AHHans]

11 hours ago, Jestersage said:

So would someone provide a good reason to use 2x skiff instead of 1x skipper in 1.9 (namely bare variant), aside from looks?

How about:

• The slightly higher Isp does make a difference for your craft.
• You want to mount it "radially".
• You have a 1.25 m mount.
• You have a 1.875 m mount.

But probably the number one reason is:

• You only need the thrust of 1 skiff.

[Superfluous J]

1 hour ago, AHHans said:

You only need the thrust of 1 skiff.

This is the primary reason I've used them.

In fact, needing one of an engine instead of 2 (or worse less than 1) of another is the primary reason I choose any given engine.

Though I do miss the days when something like 40 Sparks had better stats than 1 Mainsail

[KerikBalm]

The Skiff used to be awesome, 30:1 TWR with a very respectable 330 Isp, best TWR in a vacuum with better than average Isp (compare to a mammoth at 315 Isp). Then they hit it with the nerf-bat and increased its mass 60%!!! I know it needed a nerf, but a 60% mass increase is too much. Thats a nearly 40% decrease in its TWR! If they though it needed such a big nerf, they clearly weren't thinking straight when giving it its initial stats... who is to say they are now? IMO it needs more thrust for its size, its thrust to cross section ratio is quite poor (an often ignored stat that is important for determining how tall of a stack of a given diameter it can lift). With its poor thrust to cross section, its ill suited for lifting stacks, rendering it mainly a vacuum engine (otherwise the rocket is to short and fat). 

Its hard to think of  distinct roles for the Skiff and Skipper, without them being just slight variations. The skipper was intermediate between the Mainsail and the poodle, but now I guess it could be more like mainsail>skipper>skiff>poodle. But I actually find the poodle to also compete with it. 250kn vs 300 (pood vs skiff), 1.75 vs 1.6 tons (PvS), and 350 vs 330 (PvS).

Generally if you need the thrust of a Skiff, the craft is massive enough that the poodle, despite being a little heavier, will give you more dV, and the TWR will be similar.

I used to think of it like a mini-KR-2L, good TWR and good Isp (emphasizing the TWR more than Isp), but after the nerf, I think its junk. The KR-2l was also nerfed from its early versions, but to a more appropriate amount. I seem to remember when it first came out it was 6.5 tons (wiki's version history only lists a change from 8.5 to 9), if that was the case, the mass would have only increased 38.5% The skiff's 60% increase... insane...

[GluttonyReaper]

3 hours ago, 5thHorseman said:

Though I do miss the days when something like 40 Sparks had better stats than 1 Mainsail

It's been lost to time unfortunately, but I used to have a craft that was designed for a Tylo landing and return... and both the lander and the launcher were entirely powered by Sparks. I think there was a nuke in there for the transfer stage, but the stats on that thing were insane. 

2 hours ago, KerikBalm said:

Generally if you need the thrust of a Skiff, the craft is massive enough that the poodle, despite being a little heavier, will give you more dV, and the TWR will be similar.

Except for an atmospheric launch, no?

[KerikBalm]

1 minute ago, GluttonyReaper said:

Except for an atmospheric launch, no?

Yea, but the Skiff's poor thrust to cross section ratio means that it can't lift a tall stack, and is poorly suited to be used as a booster. Its also got a bad TWR now, so why would you use it in an atmospheric launch?

[Starman4308]

There's also one specialized advantage of 2x Skiffs: if, for some reason, you need roll control, a pair of engines gives you that. Granted, this only comes to mind because I'm accustomed to RO where reaction wheels are a decadent luxury instead of something you have almost by default, but it still is an advantage.

[GluttonyReaper]

On 1/24/2020 at 1:47 PM, KerikBalm said:

Yea, but the Skiff's poor thrust to cross section ratio means that it can't lift a tall stack, and is poorly suited to be used as a booster. Its also got a bad TWR now, so why would you use it in an atmospheric launch?

Ah my bad, I just booted up 1.8 for the first time and.... yeah. Not so great as a launch engine anymore. I was more thinking about it's previous use as the de-facto 1.25m lifter, considering it used to totally outclass the LV-T engines in literally every way  

[AHHans]

On 1/24/2020 at 12:28 PM, KerikBalm said:

Generally if you need the thrust of a Skiff, the craft is massive enough that the poodle, despite being a little heavier, will give you more dV, and the TWR will be similar.

Yes, but if you want to mount it to a 1.25 m or a 1.875 m stack?

In  general: different people have different preferences. I for myself, e.g., essentially never use the mainsail or skipper: my "heavy booster" sub-assemblies all feature a recoverable Twin-Boar in the center.

 

Edited January 27, 2020 by AHHans

[KerikBalm]

2 hours ago, AHHans said:

Yes, but if you want to mount it to a 1.25 m or a 1.875 m stack?

Use a Vector if you need the thrust, or a Cheetah if you need the dV, or a Wolfhound if you need the thrust and vacuum Isp. A bobcat if you need thrust and atmo Isp (although I don't think it is well suited to being a booster/atmospheric engine).

The Skiff was awesome... but what engine can take a 60% mass penalty, (37.5 TWR penalty, the old engine had a 60% higher TWR) and not have its usefulness suffer?

I think they over nerfed it, and it should have more thrust and mass, and be more like a skipper (about 2/3 the mass, 21:1 vac TWR)

 

[έķ νίĻĻάίή]

5 hours ago, KerikBalm said:

I think they over nerfed it, and it should have more thrust and mass, and be more like a skipper (about 2/3 the mass, 21:1 vac TWR)

 

Well then edit the part file!

[RizzoTheRat]

22 hours ago, KerikBalm said:

Use a Vector if you need the thrust, or a Cheetah if you need the dV, or a Wolfhound if you need the thrust and vacuum Isp. A bobcat if you need thrust and atmo Isp (although I don't think it is well suited to being a booster/atmospheric engine).

You've just listed my standard built   Although I tend to use Skippers and Mainsails as well until I have the Vector and the other parts needed to recover them.  Don't think I've ever actually used the Skiff

Edited January 28, 2020 by RizzoTheRat

[AmpsterMan]

As mentioned before, it's thrust-to-cross section isn't the greatest. However, when one considers that with an engine plate one can get as many engines as needed, it begins to look better. For a small mass and part count penalty, one can get a Skipper's thrust on a 1.875 stack.

[KerikBalm]

You can do that with aerospikes too, or reliants... or a single vector