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Kerbodyne SSTO Division: Omnibus Thread

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Wanderfound

Wanderfound

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Your plane has no tail; it's not surprising that you have problems.

Give it a pair of horizontal tailplane surfaces, each about half the size of the wings. Put pitch control surfaces along the rear edge. Then give it a vertical stabiliser the same size as one of the horizontal tailplanes, with rudders on its trailing edge. Put all of this as far back on the central fuselage as you can.

What is that thing on the rear of the central fuselage? It's not a stock part.

I'd recommend that you get the hang of building airframes in a standard FAR install before trying it in AJE.

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blowfish

blowfish

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@blowfish: It would be great if you can help me out. I'm new to this whole SSTO business.

What I do is angle the craft 45 degrees, full throttle and when I reach 19km, I angle the craft back to 0 degrees and build up the speed.

Is that a good flight plan?:D

With just FAR that would be fine but with AJE that isn't going to work very well. Remember, in AJE, thrust drops off with static pressure so if you climb high in the atmosphere you're going to kill your thrust and have trouble accelerating. The flight path I've found to work is watching FAR's dynamic pressure (Q) readout and adjusting my ascent angle to keep it at 40 kPa through most of the flight (I usually let it drop at subsonic speeds so that I can pass through the sound barrier faster).

Some more notes on AJE:

  • Intake spamming doesn't work anymore. Match the intake area to the needed area of the engines you're using (both can be seen by right clicking in the SPH).
  • Turbojets will overheat past about Mach 3.5. If you want to go faster before engaging your rockets, you will need RAPIERs
  • Turbojets aren't any more efficient than RAPIERs (unless you disable the afterburner)

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eddiew

eddiew

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Hey Wander et al - just thought I'd draw your attention to a nifty MK2 cockpit over in the mod section :)

Ultimately it's just a drop in replacement for the MK1 pointy cockpit, and has no other advantages than looking good on the front of an MK2 fuselage. Inspired me to create the lowest tech spaceplane I've ever gotten to orbit and back ^^ It slithers around (/rolleyes!) at about 25-30km, but it can manage a 2 ton cargo, which turns out to be plenty for probes to Duna and Eve.

El3SCQq.jpg
; perty front end. If I could make the rest of it look better I would, but I haven't earned those nice angled elevons yet :<
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Wanderfound

Wanderfound

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Kerbodyne Eyrie. Small but nifty.

Javascript is disabled. View full album

Craft file at https://www.dropbox.com/s/f3ij5r69ihpmrqj/Kerbodyne%20Eyrie.craft?dl=0

- - - Updated - - -

Eyrie Lotek. Same airframe, different engines.

hfigRPe.png

Craft file at https://www.dropbox.com/s/l629wmiyec1c6sj/Kerbodyne%20Eyrie%20Lotek.craft?dl=0

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eddiew

eddiew

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Hey Wander,

I've got some Station Science labs up, and need to ferry crew and experiments to them. Do you have anything in your fleet that is built with parts from a tier 2 R&D complex (no RAPIERS, no shocks, no MK3, and no final tier control surfaces), but could lift either a 4t cargo in a big bay, or a small cargo bay (0.1t SS experiment) plus crew of 3 plus a docking port, to Munar orbit and back?

I'm struggling to get there with just turbojets, since a single nuke alone isn't really giving me enough thrust to go from 30km@mach4 to orbit with that size of ship, but two is really heavy. Had success with a single pilot and a 2t cargo, but that's my limit so far. It might be an unrealistic expectation... or require clipping some little rockomax's inside the turbos for a poor-man's RAPIER...

Frankly I think your Javelin and similar designs are probably the way to go, but I'd be interested to know if you've ever cracked this particular nut in SSTO format :)

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Wanderfound

Wanderfound

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Pretty much all of the three engine designs will work in any of three configurations: RAPIER/Nuke/RAPIER, RAPIER/Turbo/RAPIER or Turbo/LV-T45/Turbo. Option 1 for best range, option 2 for sporty performance, option 3 if 1 & 2 aren't available.

Option 3 is the least efficient of the lot, so aim for something with a bit of fuel margin. And the late-tier control surfaces can be replaced by earlier ones with no significant harm except to the aesthetics, ditto for shock cones to ramscoops.

Even an LV-T45 ship can do Munar missions, but not without refuelling. Send a fuel tank to Munar orbit along with the ship; refuel before landing.

If you'd rather keep the nuke, just build a nuclear missile with a cargo bay and parachutes and strap some SRBs to it. A small tank on top of the SRBs can feed the nuke during launch.

Edited by Wanderfound
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UnusualAttitude

UnusualAttitude

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Eddie, I would say it depends on the orbit of your Munar station. I have actually done quite a few lo-tech Munar orbits with twin turbos and the LV-T30 (more thrust, lighter), without refuelling, because I really am that bad at building/flying rockets...

Getting a crew cabin and a light science package to a not-too-low equatorial orbit and back sounds possible to me. Getting four tonnes there sounds very, very hard. I don't have any Munar orbit pictures at hand but here is the sort of ship I used back in Tier 2 launching an ion probe (yeah, it ain't pretty I know).

In all cases the dV budget will be rather tight.:wink:

Ybt0oy5.png

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eddiew

eddiew

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That's very interesting, thanks Unusual :) I wonder if a pair of 909s would work better on the back end... slightly higher ISP and a tad lighter - but the low thrust might keep you in the atmosphere too long xD

I'd reckon that if I can get to a 100x100 LKO, with 1600 dv, I'm pretty sure I can get to Mun (~850), tweak it (~50), circularise (~250), rendezvous (~100?), and return (250)... but there's no harm in sending a can of fuel with the station, just for a little extra if I come up short.

The 4t cargo was a would-be-nice; I thought the crew cabin was also 4t, but apparently not!

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UnusualAttitude

UnusualAttitude

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That's very interesting, thanks Unusual :) I wonder if a pair of 909s would work better on the back end... slightly higher ISP and a tad lighter - but the low thrust might keep you in the atmosphere too long xD

I'd reckon that if I can get to a 100x100 LKO, with 1600 dv, I'm pretty sure I can get to Mun (~850), tweak it (~50), circularise (~250), rendezvous (~100?), and return (250)... but there's no harm in sending a can of fuel with the station, just for a little extra if I come up short.

The 4t cargo was a would-be-nice; I thought the crew cabin was also 4t, but apparently not!

Well, that will teach me not to mouth-off on Wanderfound's thread... I came up a bit short on dV :(

This was the best I could do...

6E4ZXkJ.png

I got to 100k LKO with 1,350m/s. It still has 100m/s for a careful rendez-vous and monopropellant for docking, it also has the crew cabin and I put a materials bay in there to simulate a science experiment, but lacks the 250m/s or so to get back.

The good news is that that's only a hundred and something units of LF plus Ox per return trip to pack on your station.

I'd forgotten how low the TWR is without Rapiers. Twin 909s won't work (but are a good combination with Rapiers for a small craft). Maybe you could try something with a Mk1 cockpit and the crew cabin (I just don't do Mk1 spaceplanes), and go to Mun from a lower parking orbit?

Let me know how it goes.

UA.

Edited by UnusualAttitude
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Wanderfound

Wanderfound

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If I was going to try and max out the range on a pre-RAPIER ship, I'd probably go for four turbos plus a central LV-T45 (the gimballing is useful enough to usually outweigh the efficiency cost, IMO; if going with an LV-T30 instead, be very careful with thrust alignment or you'll be doing backflips in space). Mk2 core fuselage, plus at least an FL-T800 in front of each turbo. Just enough wing to take off and land and you're set.

It'd probably still need refuelling in LKO, but it should manage Mun/Minmus and back without taking any extra supplies with you.

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UnusualAttitude

UnusualAttitude

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I didn't find the lack of gimballing on the LV-T30 to be an issue with the design I posted above, and that's with a single reaction wheel and no RCS; she held straight even at full thrust.

I still think it may be possible with a lighter design. If not, then it will be a choice between refueling in LKO (more efficient in the absolute) or having some fuel at your Munar station (less efficient but saving you real time by cutting out a rendez-vous).

I'm looking in to your tourism challenge, Wander. The problem is that I don't have enough Kerbals available for recruitment. Do you just have to wait for more to come along? I will need a LOT, especially if there are failures...:sticktongue:

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UnusualAttitude

UnusualAttitude

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OK, I managed to get something to 100k KO with 1,650m/s left, but it ain't pretty.

XDs4GQs.png

I think it should be called the Hammerhead. Now we just have to make it look good...

Anyway, what you originally described may be possible, Eddie.

Sorry for hi-jacking your showcase thread, Wander, but I can't resist an efficiency challenge. :wink:

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eddiew

eddiew

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Good lord, I am impressed sir!

...now to actually move my station to Mun. It's been orbiting Kerbin for the last 100 days because it generates 1 science per day from studying furry critters.

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eddiew

eddiew

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Wow, nice one Wander :) I might try giving it a couple of those tiny orange radial engines, see if the extra thrust (and shallower ascent) doesn't help it out rather than hinder it... (probably hinder, but I need to know!)

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