pointless engine?

[Spricigo]

funny how my disregard for the Thuds caused the discussion to veer toward decouplers...

Small hardpoint cost 60 funds and requires Advanced Aerodynamics (160science)

Strutural Pylon cost 125 funds and requires High Altitude Flight (300science)

At this tech level I’m usually launching larger rockets with larger payloads, engine choice goes toward skipper, mainsail and twin-boar. I can't say if at this point Thuds are interesting for "just a bit more power" since I never needed "just a bit" was either "had more than enough" or "needs a couple kickbacks"

But notice, there is a lot of my preferences(and maybe prejudices) about not using the thuds. I don't design my vessels to be the most efficient cost wise, I'd rather pump the TWR a bit, so it reach orbit a bit faster . Launching feel like the major expenditure of timetoplay and I prefer to waste some funds than waste some timetoplay. Likewise I don’t give much consideration for a choice that just save some funds (game gives plenty) if there is an option that use less timetoplay (scare because real life)

And in the limited cases where I would consider Thuds they never looks like a good idea to me.

[GluttonyReaper]

17 hours ago, AeroGav said:

Small Hardpoint costs only 60 Funds  and is a better way of attaching your Thuds.  That way you can lose their mass when surplus to requirements. But , it's a Tier 6 tech (Advanced Aerodynamics, 160 Science) so may not be available.

Now that I think about it, that's essentially the same as what Mercury-Atlas used to do. If it's good enough for NASA, it's good enough for me!

[Spricigo]

4 hours ago, GluttonyReaper said:

Now that I think about it, that's essentially the same as what Mercury-Atlas used to do. If it's good enough for NASA, it's good enough for me!

that reminder me:

 

[Razorforce7]

These engines are good for.

A:Very small craft.
B: Thrust assisting ION stages for meeting thrust requirements in whatever scenario you can come up with.

And hereby the clarification of what I consider to be the usage of said engines that describes the  "B" answer given above. Since it might be vague what I mean by it.

For example!

I made a very low weight single lander/ascent stage for Moho in 1.02. This topic reminded me of rebuilding it and I will. Maybe I will post a pic if people wanna see how it looks. Which is alot better then a long explanation ofcourse.

This is a Mk 2 lander can with 2 x mk 1 crew cabins (5 seats)
It can get to Mohos surface from LMO and back to orbit with a much lower weight if I use a combination of ION engines and low thrust LF/O engines instead of just using LF/O or LF for that matter.

2 ant/spider engines will give this design the necessary extra thrust for soft landing and for getting back of the ground.
Furthermore the Xenon fuel is reduced in the tanks as is the LF/O to give it just enough delta v to do the trick and less weight to get the thrust right.

This design uses the same ion engines with fuel crossfeed from a undocked xenon fuel core left in LMO I use to decelerate at moho arrival and for rendesvouz to get back to kerbin further reducing initial launch weight. Yes, I am a as light as possible kinda guy. The xenon fuel left in LMO can be docked with again. Some parachutes, wing parts and a eve gravity assist make the whole setup recoverable.
Yes the interplanetary ION transfer stage is painfully underthrusted, and yes the xenon fuel core left in LMO has....lots of xenon fuel (relatively speaking ofcourse) :p.

The "Twitch" in this design would have to much thrust when combined with the ION engines. And that is because Ion engines and the Spider engines burn in tandem. The LF/O runs out by the time I raise my moho AP just enough to maintain altitude with the ION engines on ascent.
Using a "twitch" for more TWR really doesn't do much nor does it suffer the design.
But the well dosed TWR with the spiders give the ascent part of this design a more fluent feeling if I toss the twitch and use 2 spiders.

The point in this design is that these engine combos allow me to make very low weight moho landers for a multi crew lander stage. (not necessarily for just moho ofcourse)
But especialy in mohos case since lower weight is so mo-holy crucial.

Substituting the Twitch for the spider/ant simply gives this design unecessary amount of TWR. That is good, but unecessary because it assists the main ion engines and it would only require more of both fuels due to added weight albeit margineable.

The LF/O rocket part is just for assist since the ION setup is just below the required surface gravity of moho. Or better said, I haven't yet found a way to do it on ion thrust only.
In case "you" did, then I demand explanation.

The total LF/O delta v is about 250 m/s. With which I need to both assist landing and ascent.

Also, some engines in KSP are of smaller scale, some are of bigger scale. And yes, some are better for some purposes. Like, Gimbal vs no gimbal, light vs heavy, atmosphere vs vaccuum, and/or efficiency versus thrust.

But it's still limited within the LF/O range a.k.a. "chemical engine range of posibilities"

I think the Spider/Ant are closest to being a seperate category among LF/O engines. They are relatively heavy for their size.
But if you only need 2 of them for Thrust assisting, the twich is less of an option.

Basically the engine need is determined by the scale/size of your operating stage. Puzzle long enough and you'll find uses for every part in the game.
Are you operating a stage that is very light to the point where spider/ant engines become the better choice, then that is the engine of choice.