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The supplementary SStO thread [FAR]


RealHogweed

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Jeb got stranded on Laythe with untested SS to Laythe and back after too deep aerobrake maneuver (~93km) at jool.

So Bill came in for the rescue.

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Billys craft was improved version with JetIntRocFuel pods. Technically an SSTO because pods are ejected (and deorbited with sepatrons) in parking orbit and craft starts then with full tanks.

Building trick here is that the main jetmotors are angled towards COM to provide flameout stability with multiple jets design.

Pod motors are shut down early enough for good safety tolerance.

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Tricks here.

BirdDog rower wheels (not my invention)

Rescue and rovering seat located at front landing gear. (Jeb sat here two long years :D)

Wings and fueltanks connect in brick wall like structure making the frame very stiff.

Structural parts is used to make landing gears higher provide high impact tolerance and some flexibility.

Wide wheelbase resists "sumo wrestler dance of death" effect at takeoffs and landings.

Nuka motors in front to keep COM in the middle of the craft.

m7sJrxY.jpg?1

So post your building tricks and features that can be added to make our planes better.

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But since I don't really do asparagus pancakes, building stable rockets has been pretty easy. The problem I'm having with drogues is that the entire ship is inside a fairing (this is not strictly necessary, and it steals much more DV than it saves, but it's very pretty) this means that the tanks on the inside wobble around like crazy. I may see if airbrakes work--if I can find a good place to mount them.

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Eh, two jets and one or two Nervas will get reasonably hefty planes up - and the much better ISP of nuclear rockets is pretty handy when you don't have much fuel tankage. Never really tried rockets with wings larger than what's needed for stability, was something I've been meaning to look at.

You really want to start your gravity turn at under 1km, btw...

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A FAR SSTO without SABREs is a different ball game. This is the only one I've managed, and it was accidental (I was testing how much wings would affect dV requirements, and the answer was A LOT)

I find stock SSTOs harder

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For trajectory, I'll climb fairly rapidly to about 10km, then aim prograde maybe 10 degrees off the horizon. You won't ascend very fast, but the key isn't getting height, it's getting tangential velocity. If I can get to about 1800m/s by the time I have to cut jets, circularizing will be quite simple.

Additionally, I find that what really helps is "porpoising."

Climb up at maybe 45 degrees, wait til you have to cut jets, and then simply coast back down. Keep your nose prograde, and you'll find that once you're back down to maybe 16-20k, you're doing ludicrous speeds. Now you continue like above with a shallow climb, and perform a standard insertion maneuver. I find this saves a lot of fuel (my first SSTO to use this method made it to a stable Munar orbit), but it is definitely trickier with regards to stability.

Edited by Torminator
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  • 2 months later...

I was in need for a shuttle capable of ferrying single Kerbals inside the Kerbin SOI. However, as I play together with some buddies via KMP, we currently have the stock-parts only rule still in place. Makes for a nice challenge anyway ;) . As plugins are not limited by KMP, FAR has found its place again. As I also run with Mission Controller, costs are an important factor as well, so a reusable SSTO is attractive long-term.

ssMXoxe.jpg

It's actually super easy to get this thing to space: Just use SAS and go for maximum pitch up continuously until 15km, then reduce vertical speed and let it pick up horizontal speed until reaching ~20-25km, though you have to be watchful of engine flameouts up there, as it only has the two ram air intakes. Once you reach the usual ~1650m/s where the jets lose thrust dramatically, switch to the nuke and do a regular gravity turn. While getting to orbit takes a while due to the low thrust, it is insanely resource efficient. Currently I end up with about 3-4km/s(!) deltaV left in a 120km orbit which is plenty to go around for Kerbin SOI. This should even increase if dropping the excess jet fuel in a LKO fuel depot before proceeding outwards.

Currently its takeoff weight is 16,5tons. At 120km stable orbit I'm down to ~13,5t. I might shave off a couple of fuel tanks, shortening the mid-section to better protect the nuke engine during T/O and landings. I also am considering replacing the two outer FL200 with RCS tanks, giving more RCS for docking or moon landings.

Notice the minimal wing surface: Due to the wide body, not much extra was needed. Maneuverability in-atmosphere is very limited due to that, but it's a space plane, so I don't care. By not adding canards or any more lift and control surfaces than necessary, it really is more of a SSTO rocket with horizontal takeoff and landing capabilities. The low weight and bulkiness also comes in handy when docking in space (easy RCS control, no danger of bumping into stations) and even allows for landings on the Mun or Minmus.

Currently there is one danger however: The two solar panels are the only electricity generator, and they are in full air flow. The slightest negative AoA during the "hot phase" of launch or reentry can quickly burn them up (yeah, using DRE as well). Then again if you have a negative AoA in the hot phase, you'e doing something very wrong anyway.

I'll probably build a couple of derivatives of this for different tasks (larger crew capacity, payload capability...), I really like how versatile it is due to the huge deltaV surplus I have right now.

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I would keep those tanks, and reduce the midsection like you were thinking, but I would add those radial mono tanks towards the front. This would give you the extra mono propellent you are looking for.

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  • 4 weeks later...

Some of my FAR SSTOs and prototypes. All are either Stock or stock+B9 parts. If you look near the end, I have a surprisingly flyable, maneuverable and durable craft that can carry

146 Kerbals to orbit in FAR with fuel to spare

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Another plane of note is the VL-110EF Spearhead. Made entirely from stock parts for use in either FAR or stock aerodynamics, it is capable of throwing its 11.1-tonne (takeoff weight) self into orbit with over 1 tonne of rocket fuel remaining.

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Edited by Pds314
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