Grand tour project - what to choose?

[Alchemist]

So, I was thinking of a grand tour (with ISRU) project, but in the end I found myself unable to decide between several concepts of the main unit (that is the lander).

General elements (for all the options):

Crew: 5-6 total, 3+ in the lander.

Orbital craft: lab (for SCIENCE!!!), emergency reentry vehicle (or part of it - may cobine with lander cockpit), interplanetary propulsion (nukes; unless the lander can take this role), bunch of fuel.

ISRU: the lander will be capable of refueling itself on the surface of wherever it lands (how much panels you need for this around Jool?)

Eve is just Eve: well, this requires a separate expendable vehiche (and maybe something more...). Crew - most likely 2.

Moho is hard to reach: the lander should be capable of getting fuel from Moho to the orbital craft. However the Tylo condition should cover it.

Tylo forgives no mistakes: the lander should be capable of fully refueling on the surface and taking off with full tanks to reach orbit (reliance on the orbital craft's fuel reserves for transfers). This should also cover the landing conditions (since the touchdown will be mostly dry).

Laythe may be worse than Tylo with ISRU: see craft notes.

Lander options (what should I choose?):

A) Plain chemical lander. Codename: Manganese. Most likely aerospikes, since we need both Laythe and vacuum performance. Options for Laythe are: 1 - just have enough delta v; 2 - land there without ISRU module; 3 - RAPIERs (all or some) - trade some vacuum performance for Laythe peformance; 4 - additional jet addon for Laythe only.

Nuclear lander. Codename: Radon III. NERVAs + chemical. Should be capable of Moho/Duna/Vall on nukes alone (with no oxidizer; 4 nukes may be enough), Tylo would use both types of engines. Laythe problem even worse than with the previous design, same options (no-oxidizer RAPIER+NERVA Laythe ascent might be most viable). Provides interplanetary propulsion.

C) Chemical-powered VTOL plane. Codename Vanadium. Yeah, somewhat inspired by Kuzzter's Humblebee. VTOL engine requirement - Tylo touchdown (after slowing down with the mains, with mostly dry tanks), for Tylo/Laythe takeoff with full tanks just getting the nose up and then using mains is an option. Efficient for Laythe exploration, Rapiers+Aerospikes for the main propulsion.

D) Nuclear plane. Codename: Ku-104. Primary propulsion: NERVAs+RAPIERs. VTOL will have more thrust than mains, large part of Tylo asent will be upward not forward. Laythe - definitely RAPIERs, VTOL system for tricky landing sites.

Ah, yes, one more thing:

kOS - I'm going to use the heck of it.

So, what do you think I should make?

[Mister Dilsby]

Appreciate the shoutout Myself I would indeed probably try ©, but rather than the Hummlebee style V/STOL layout would make it a 3-wing tailsitter like my Pogo. (though with all the ISRU equipment it would be several times larger than any Pogo I've ever launched!) That gets rid of the VTOL system entirely, and you could use parachutes to assist landings on planets with atmosphere. Hummlebee's VTOL was really just an assist for horizontal landings on Kerbin and Duna, and never intended for landing in vacuum.

[Alchemist]

Thanks for the opinion!

A tail-sitter is an option, but it's something that mostly boils down to (A) variant (but may be the best version of it for Laythe - given some real control of the landing site selection). The idea with the planes is exactly about the ability to just interrupt the level flight and switch to vertical landing (your Cobra maneuver definitely bought me - initially I was just considering the normal landers) which seems best with the horizontal configuration.

Of course, since I'm going to extensively use kOS, the VTOL system (if I take a plane) will be aerospikes (maybe with some smaller peripheral engines for additional control) with autobalance and throttle-steering. I'm not flying that without assistance - I'm a terrible pilot, especially when such things go out of control (I've had some experiments with VTOL before, but almost all of them ended losing balance, however with a proper kOS script it may really work).

[FyunchClick]

Hummlebee's VTOL was really just an assist for horizontal landings on Kerbin and Duna, and never intended for landing in vacuum.

Works like a charm though, I'm liking it so much I've completely gone off putting angled engines on my VTOL belly landers since I ripped that idea from your Humlebee. I took something quite similar to it to the Mun for a trial run, and after bleeding off most speed with the main engines, that final slow touchdown pulsing up on RCS controls is very smooth, especially when you "control from here" to that belly mounted docking port and point SAS to prograde.

I did make sure the torque for COM and dCOM is as low as possible using the RCS build aid, but even if it's a bit off, the same vernor thrusters you use to land will try to keep attitude with SAS turned on and they're got plenty of power to keep you straight.

[AxleMC131]

I did make sure the torque for COM and dCOM is as low as possible using the RCS build aid, but even if it's a bit off, the same vernor thrusters you use to land will try to keep attitude with SAS turned on and they're got plenty of power to keep you straight.

That brings up an interesting point. Apologies if I digress briefly from the main point of this thread, but I've heard a lot of talk about using the Vernor thrusters as VTOL engines.

I gotta know... How effective actually are they at that job? I have to say I very rarely use the Vernors, except on really big launch vehicles that need some kind of RCS to keep them stable during ascent. What are they like as VTOL thrusters? Efficiency? Power? Why would you use them over conventional engines, or why not?

[FyunchClick]

A tail-sitter is an option, but it's something that mostly boils down to (A) variant (but may be the best version of it for Laythe - given some real control of the landing site selection).

Do you think it's possible to do a ship that can do an airbreathing SSTO for Laythe and be a rocket powered SSTO for Tylo at the same time? AFAIK, the first relies mostly on getting a good kick from airbreathers with a small push from rockets (of which only a little can come from a low TWR one like a LV-N) to work up to the 2.9 km/s dV mentioned for Laythe orbit; the second needs 2.3 km/s of rocket power with a solid TWR and dedicated airbreathers are just dead weight (numbers from here).

Wouldn't you just be better off going for a high TWR rocket SSTO, with some control surfaces for controlled gliding on low throttle on Laythe, that can do at least 2.9 km/s to tackle both places?

I've never done a Jool tour yet, I'd be genuinely interested to see what the opinions are of those who have.

- - - Updated - - -

What are they like as VTOL thrusters? Efficiency? Power? Why would you use them over conventional engines, or why not?

I've only got limited experience, but as a tool to do a soft VTOL landing they seem very friendly so far, because they also double for attitude control, and I think they're easier to manage than angled engines as they're controlled independently from your main engine throttle (which you can keep operating independently) and pulsing them is a very easy way to control your altitude and rate of decent. Can't comment too much on the ISP (in atmosphere or out) but I don't care so much for that as I've never intended to use them for long periods of time. You'd need quite a few of them to lift off very large payloads on high-g world, so they may not be ideal for those scenarios.

Even on a high-G world where they may not provide enough thrust to lift a fully fuelled and loaded ship (like on takeoff on Kerbin), they can also help in shortening run-way length if you're doing a horizontal takeoff with your space plane as they can provide additional lift to that generated by the wings until you have enough airspeed to stay airborne on wing lift alone.

Binding them to a key to enable or disable them, as Kuzzter mentioned when he discussed his humlebee, is quite crucial for being able to perform any sort of docking maneuvers.

[Mister Dilsby]

Binding them to a key to enable or disable them, as Kuzzter mentioned when he discussed his humlebee, is quite crucial for being able to perform any sort of docking maneuvers.

Yes--you absolutely have to! For me the main advantage is the attitude control. If you distribute the thrusters reasonably well your ship will stay pointed where you want it to go. In most cases you only need the Vernors for short bursts.

Axle, if you'd like to try mine out here it is. You can of course take the plane off the launcher if you just want to test it out on Kerbin.

[cantab]

I think what I'd go for is a chemical-engined lander that's up to most landings, and then dock-on lower stages for it to support Laythe and Tylo (and maybe Moho). For Laythe that could even be a plane that the lander docks into.

[Alchemist]

Do you think it's possible to do a ship that can do an airbreathing SSTO for Laythe and be a rocket powered SSTO for Tylo at the same time? AFAIK, the first relies mostly on getting a good kick from airbreathers with a small push from rockets (of which only a little can come from a low TWR one like a LV-N) to work up to the 2.9 km/s dV mentioned for Laythe orbit; the second needs 2.3 km/s of rocket power with a solid TWR and dedicated airbreathers are just dead weight (numbers from here).

Wouldn't you just be better off going for a high TWR rocket SSTO, with some control surfaces for controlled gliding on low throttle on Laythe, that can do at least 2.9 km/s to tackle both places?

Given that Laythe & Tylo are the most expensive parts of the trip, the optimal solution is probably about the right balance. Laythe takes more than Tylo to get from surface to orbit, but can use the atmo as the advantage. I think of RAPIER+Aerospike combination for both non-nuclear variants - no need to have all the TWR from jets alone, they may just be used to win a bit of delta v (although the plane, if I choose it, may be capable of jet-only flight in lower atmosphere, but it's takeoff would take everything anyway). And for vacuum operations the RAPIERS turn into ISP/TWR tradeoff - meaning that they should be used mostly at the parts where thrust is critical.

Looks like the nuclear versions are not too popular in the poll. Well, they don't win much in the proposed scale of lander operations (would be more viable in case of not having the mothership with fuel reserves). Strangely, analysis of this concept started exactly with the nuclear lander, but then I got slightly disappointed in nuke performance in the newest versions.

[AxleMC131]

I've only got limited experience, but as a tool to do a soft VTOL landing they seem very friendly so far, because they also double for attitude control, and I think they're easier to manage than angled engines as they're controlled independently from your main engine throttle (which you can keep operating independently) and pulsing them is a very easy way to control your altitude and rate of decent. Can't comment too much on the ISP (in atmosphere or out) but I don't care so much for that as I've never intended to use them for long periods of time. You'd need quite a few of them to lift off very large payloads on high-g world, so they may not be ideal for those scenarios.

Even on a high-G world where they may not provide enough thrust to lift a fully fuelled and loaded ship (like on takeoff on Kerbin), they can also help in shortening run-way length if you're doing a horizontal takeoff with your space plane as they can provide additional lift to that generated by the wings until you have enough airspeed to stay airborne on wing lift alone.

Binding them to a key to enable or disable them, as Kuzzter mentioned when he discussed his humlebee, is quite crucial for being able to perform any sort of docking maneuvers.

Yes--you absolutely have to! For me the main advantage is the attitude control. If you distribute the thrusters reasonably well your ship will stay pointed where you want it to go. In most cases you only need the Vernors for short bursts.

Axle, if you'd like to try mine out here it is. You can of course take the plane off the launcher if you just want to test it out on Kerbin.

Ah, of course! They respond to the RCS controls. *facepalm* Should've remembered that means they automatically try to keep your attitude as well. Very handy indeed.

I see what you mean about binding them to an action group though - you definitely don't want them activating and wasting fuel during minor deep-space manoeuvres.

Also, I may just try out the Hummlebee, Kuzzter. I followed your graphic series briefly, and found it pretty entertaining.

[Monsterlunch]

Eve is just Eve: well, this requires a separate expendable vehiche (and maybe something more...). Crew - most likely 2.

Eve beeing just Eve, i wouldn't consider bringing more than 1 Kerbal to the surface. The resulting Mass difference may not seem too bad, but escaping the purple hell with a 2.66 ton MK2 LanderCan (2*MK1 = 1.32) instead of a MK1 LanderCan at 0.66 tons results in a bigger launcher, therefore bigger transfer stages and so on.... (You might even consider EVA Seats, using the kerbals jetpack for Orbital insertion. )

The prestigious effect of a 2 Kerbal party on Eve would be enourmous though.

Regarding Tylo/Laythe, you could probably increase Fuel Storage on your Interplanetary transfer Vesell, bring along a Seperate IRSU Lander, refuel at the smaller moons and therefore save the fuel for bringing down and up all the Mining Gear from Tylo/Laythe.

Edited September 24, 2015 by Monsterlunch

[magnemoe]

I would go for an chemical engine lander, this tread inspired me to make one.

it should have enough dV to land and reach orbit on Tylo and laythe if it mine on the surface. For Laythe I would do an powered landing, this would also increase landing accuracy who is critical on Laythe.

Lander has an docking module with an hitchhiker module and 3 large ore tanks who is docked on bottom and can be used on lower gravity bodies to bring a larger crew and to bring more ore back.

Will probably use more smaller tanks on the final version to make it easier to adjust amount of fuel needed to land on various bodies.

[cantab]

I would be worried about the aerodynamics of that on Laythe. I had trouble on Serran, a mod planet that's similar but a bit smaller, with an unaerodynamic ascent vehicle that flipped out of control. (This one: https://flic.kr/p/xdRVMo , sorry for zoomed out picture.)

Then again I use FAR, stock might be more forgiving even in 1.0.4

Edited September 25, 2015 by cantab

[Warzouz]

Nice desgn. Beware of aero flip on Laythe. Your mass seems to be quite backward and you do'nt have any fins. Your ship may probably flip.

EDIT : Ninja'd

[FyunchClick]

you definitely don't want them activating and wasting fuel during minor deep-space manoeuvres.

Weeellll, it's not so much the waste of fuel as the flying off at 5 or 10 m/s just as you were easing into a docking port at 0.1 m/s and pressed 'k' for a final correction. They're pretty powerful and you'll probably put on quite a few (you will need it to lift of on rcs at I think 30+% of its wet weight at KCS in order to use it to brake on Duna, less on the Mun). For VTOL purposes, they only need to point straight down, any other direction is a waste of mass and partcount.

[Alchemist]

Well, looks like conventional lander versus VTOL plane go almost equal (although the nuke option for the plane seems to be more popular than for the lander)

And after some experimenting ("Get off Kerbin, damnit!!!") I voted for something I made to work (still needs couple more systems installed... and a lot of configuring).

Well, it has quite a strange ascent sequence:

1) Runway takeoff on jets (barely... oh well, on Laythe it'll use everything)

2) Almost Mach 1 horizontally then start climbing

3) Add aerospikes during climb, switch them off when jets pick their power back up at level flight at high alt.

4) Push over 1 km/s, then start climbing further.

5) engage aerospikes, turn rapiers to closed and so on...

And a small spoiler... if this one works, there might be another vehicle of similar kind present on the mission as well...

[Mister Dilsby]

I like it A LOT! Maybe because it reminds me of a certain other ship -- but seriously it looks to be much more capable than Hummlebee, able to SSTO AND neatly solving the drill drag problem with that belly mounted cargo bay. Well done!

[Alchemist]

Thanks! I was inspired by your design, but for this mission it required couple upgrades.

The cargo bay is an interesting option - other than the drill, it also turned to provide a perfect spot to place a scipack in the direct vicinity of the cockpit (since the craft going to land in places where the jetpack doesn't cut it)

.

... and the forward VTOL thruster.

I was actually going to have a smaller segment inverted, but the drill turned to swing a bit wider. On the bright side, the resource scanner dish fits in there perfectly. Heh, packing everything in there took about as much time as getting the craft to fly

As for it being SSTO - if the craft should be capable of launching from Laythe, might as well make it capable of launching itself from Kerbin.

"It can land anywhere! Except Jool - there's no surface."

"Even on Eve?"

"Land - yes."

[tewpie]

This is a Stock-NoEveGrandTour-Nuclear-VTOL-ISRU-SSTO I've been working on...

http://imgur.com/a/azz55

Looks like we had the same idea with the forward cargo bay with underside doors. Notice my solution to the wide swinging drill

[FyunchClick]

This is a Stock-NoEveGrandTour-Nuclear-VTOL-ISRU-SSTO I've been working on...

That's a very Kerbal way of getting into take off position you got there.

[FyunchClick]

The cargo bay is an interesting option - other than the drill, it also turned to provide a perfect spot to place a scipack in the direct vicinity of the cockpit

Yeah it is, isn't it. This was what I cooked up for my interpretation of the Hummlebee (which is definitely not a Kerbin VTOL, and is brazenly plagerized from Kuzzters without even attempting to hide it ).

But as to the science pack, I did it like this:

Which allows me to just click on the backdoor and EVA straight into the cargo bay as shown here, no jetpack required at all.

(addition of a third engine there gives me enough punch to launch it from Kerbin with just a bunch of kickbacks strapped to the wings, and that much easier to handle around KSC)

And when you want to do a science harvesting during a suborbital, just leave your scientist in the deckchair.

Plus I love those little observation windows at the top of the MKIII cockpit. Just like the real thing. Shame to hide those...

Edit: is that a Surface Scanning Module mounted on the right side of the bay?

Edited October 4, 2015 by FyunchClick

[Alchemist]

Well, I've made a video of my craft. Unfortunately my computer doesn't really want to cooperate with such projects (it was actually recorded a while ago, but I really had problems with editing the video), so I guess the actual big mission will take place when I get a new PC...

 

[FyunchClick]

On ‎26‎-‎1‎-‎2016 at 11:03 PM, Alchemist said:

Well, I've made a video of my craft.

Didn't see the entire thing but I did pick through some highlights. Did you eyeball that Mun landing or was that mechjeb? That looked pretty smooth and the landing thrusters seem to work like a charm.

[nosirrbro]

Nuclear plane all the way. I myself happen to also be constructing the dezign for a similar (But with much less delta-v) aircraft, and the prospect is awesome especially for Laythe or Kerbin ascent!

EDIT: Oh, I see you've already made a different plane. Oh well then.

Edited January 27, 2016 by nosirrbro

[Alchemist]

10 hours ago, FyunchClick said:

Didn't see the entire thing but I did pick through some highlights. Did you eyeball that Mun landing or was that mechjeb? That looked pretty smooth and the landing thrusters seem to work like a charm.

That was kOS. Most of the flight was either fully or partially controlled by kOS scripts. Except landing on Kerbin - that was manual. And rather sloppy.