Mission: SSTO to LKO and return to KSC

[Hyomoto]

Background:

One of the major parts of the game that has eluded me so far has been planes. I can takeoff, transfer, dock and land with rockets but I always thought the aerodynamic model in KSP was too fudged to be worth giving much effort. However, with mechanical lag and assignable control surfaces on the horizon I couldn't help but want to finally breach my final Kerbal frontier and learn to do this. I saw something on the live stream for 0.23 that made me realize a major flaw with all my designs. After 0.21 I'd forgotten SAS and the torque-wheels are separate entities, and I'd been basically trying to fly by jamming torque-wheels into a plane to keep it under control. What I saw during the live streamâ€â€they turned the wheels off. I gave it a shot, and I realized why my planes always jerked and twerked, the control surfaces are fighting with the torque wheels!

Mission Objectives:

Build a single-stage-to-orbit craft.

Fly it to low-Kerbin orbit.

Land safely, bonus points for getting anywhere near the Space Center.

Design Phase:

- X-SOLR-1 -

My original attempt was this mess. I'm not really sure I learned what to do here, this is mostly a cluster of what not to do. I started off with the trashcan tank and slapped a Skipper on the the back. Next up was the wings. Not knowing how many engines I'd need, I went all out. Next came some landing gear, C-130 style and off I went. This thing did not fly at all, I'm pretty sure it went into the ocean on the first flight. So, needing more lift, I went ahead and plastered it with wings wherever they'd fit. Now, I may have been able to get this thing to go one day, but this is where my design philosophy was born. If it had to look like this, it was going in the trash.

- X-WHSPR-1 -

Fresh with the sting of total failure, I decided on two craft. The first one I'd try my hand was is the WHSPR variant. It would be a small and only use a single engine. I figured it would be easier to grasp the basics with only a few pieces. I designed it around two fuel tanks, one rocket and the other aircraft thinking this should be enough oxidizer to get into space with sufficient altitude and speed. The WHSPR design, while ultimately unsuccessful did not change much across its variants. They all used the same hybrid LV-T45/Turbo Jet hybrid. I moved the intakes around to taste, but the core design is the same.

This shows the engine with the intakes removed, I originally used the LV-909, but it didn't have enough thrust (or so I thought at the time) so I swapped it out and added an extra strut to separate the two. The main issue I had with this plane is burning up in the atmosphere or stalling out, both dead ends in terms of success. The solution? I went ahead and rebuilt it.

- X-WHSPR-2 -

To deal with the stalling I swapped the fueltanks. The center of lift and gravity were very close in the WHSPR-1, so this moves one ton of weight forwards. I also adjusted the fuel flow so it drains from the rear tank first, keeping the front of the aircraft heavier throughout the entire flight. The ejection mechanism was updated after a few accidents of varying types. This is the type used on all future variants and the SOLR-designs.

I had a couple coupler malfunctions and the parachute would heat up during ascent causing it to explode so I added the sepratons and a heatshield for the parachute. I was getting good results out of the WHSPR-2 variants, I made it up to 27km at 1700m/s but never had enough fuel to circularize the orbit. This was the first craft to actually breech the atmosphere, however, so it was an important stepping stone but I had to use oxidizer drop tanks and it was at that point I felt it was too complicated and a fresh start was needed.

- X-SOLR-2

I had learned enough from my time with the single engine design to know two things: I needed more fuel, and I was tired of mucking around with the hybrid engine (seriously, the amount of time wasted on various malfunctions from unset action-groups to loss of fuel connectivity was maddening). So I started with a basic fuselage design, incorporating the same neck, ejection seat and command pod as previous variants. I decided the rocket engine would go in the rear rather than on the wings, and but I wanted an actual tail section. This fuselage is hideous in my opinion because there is no way to even it out, and having the engine just slapped on the back is far from pretty, but how to do both? Easily enough.

Originally the design only used a single LV-T45 engine, and I felt I'd need two jet engines to get off the ground though now I could probably swap them. But this looks much better eh? Well, the first attempt didn't go so well. I had a heck of a time with the wings, but I stuck by my guns. I wasn't going to just splatter wings on every available surface, and at the same time I had to have more lift. I couldn't get off the damn runway! The first addition were the canards up from which helped a bit, but at about 10km I'd have pitch full up and be loosing altitude. It just wasn't going to happen. So then came the final design you see here, and wouldn't you know? She worked!

Mission Phase:

For those who struggle with getting one of these things going, I'll provide the information I kept hoping someone would post. I took off and pulled my nose up to about 45 degrees and let it ride until around 10km. At this point this bird is at full pitch and wants to start dropping altitude, so I had to turn on the torque-wheels to keep the nose pointed up. At 12km and 400m/s I was able to turn off the torque again and slowly pitch down to build up speed. At about 20 degrees and 1200m/s I was at 0.9 on intake air and started heating up. I turned the torque wheels back on, engaged the rocket engines and shut off the jets. Or so I thought. My craft started bobbing up and down and I was worried it would stall out, but coaxed it to a stable 60 degree climb before noticing I'd actually turned OFF the torque wheels. Fixing that error, I pulled the nose up and pushed my apoapsis out to 85km and shut off the engines. From there I just had to ride to my apoapsis and circularize my orbit with enough fuel to deorbit and attempt a landing at the KSC.

I wish I had photos for this part but it all went poorly and I was focused on whether or not I'd have to bail and fail or make the landing. I overshot the KSC by a considerable amount, I did my deorbit at about 90 degrees from the KSC and I really should have done it closer to 80 I think now. Doing a 180 degree turn around at 1700m/s is a very long process, and by the time I'd succeeded I saw my fuel was at 22 and around I was on the other side of the ocean. I managed to coax her in though with a sweet 8.26 to spare so it ended up being less intense than I'd thought and I landed close enough to the KSC for them to send out a truck to pick up the pilot.

Still a ways to go until SSTO will be a practical tool for me, but just like my first rocket into orbit, this is a great feeling!

Result: Success!

[DisarmingBaton5]

Er... Single stage to orbit to low kerbin orbit? A bit redundant.

Kudos anyway, I've only ever built one HTOLSSTO.

[Hyomoto]

A bit redundant indeed. A bit of booze and a long post lead to poor choices!