A mostly successful attempt at an SSTO

[neamerjell]

Mods used:

B9 Aerospace

Procedural Wings

MechJeb

MechJebAndRemoteTechForAll.cfg

KW Rocketry (I think, for the detachable tanks)

NavBallTextureExport

I saw an image on this forum and liked it so much that I built a rough copy of it. If someone knows who made the original please let me know so I can give him credit.

My version copies the fuselage design's clever use of the engine mount up front for mounting the intakes. One major bug in my design is that it simply won't fly unpowered. It flips, flops, waggles and shimmies all over the place and is dang near impossible to control unless the engines are at least at 1/3 to 1/2 throttle. I added chutes for landing. Since taking these screenshots, I have added two reaction wheels, one right behind the cockpit and the other just in front of the tail. I have yet to test it, but perhaps it will increase maneuverability while in orbit. The cockpit's built in reaction wheel just can't cut it.

Here is my version:

[snipekill1997]

You do realize that that is not an SSTO if those detach. Also they should be liquid fuel, not oxidizer. Oxidiser is for rockets only, so you want to have it on the main craft and extra liquid fuel pods on the outside.

[horndgmium]

You do realize that that is not an SSTO if those detach. Also they should be liquid fuel, not oxidizer. Oxidiser is for rockets only, so you want to have it on the main craft and extra liquid fuel pods on the outside.

You do realize that because they're detachable doesn't make them a necessary stage? Giving someone design advice doesn't require you to be so condescending. Also, he can put the whatever kind of fuel wherever he wants, his design doesn't require your godly input, Mr. 2nd post on the forum.

If you're going to get on here and criticize for the purpose of criticism then maybe you should just delete your account.

[qromodynmc]

You guys just started an argument which I was wondering,If a space plane uses droptanks,is it count as ssto? I mean droptanks are used very much in real life by fighter planes,I dont think it would be a big money problem.

[neamerjell]

Actually, my mistake. The detachable tanks are indeed fuel-only tanks. And okay, so its actually a TSTO, if you want to argue semantics. I was hoping for some input on the flippy-floppy, almost uncontrollable unpowered flight. It does not glide at all. In fact, given its way, I think it would land tail first, based on its tendency to flip over at low speeds.

One idea I was thinking of was using Infernal Robotics to build F-14 Tomcat style wings that I could reposition when needed. Anybody have a better idea?

[neamerjell]

You do realize that because they're detachable doesn't make them a necessary stage? Giving someone design advice doesn't require you to be so condescending. Also, he can put the whatever kind of fuel wherever he wants, his design doesn't require your godly input, Mr. 2nd post on the forum.

If you're going to get on here and criticize for the purpose of criticism then maybe you should just delete your account.

You are over reacting. He's totally right. It was my mistake - they are indeed fuel only tanks, and the fact that they are detachable makes my creation a Two Stage To Orbit (TSTO).

[Robotengineer]

You could use action groups for the drop tanks, and combine the stages, thus still being a SSTO.

[brianorca]

Show us a screen shot with the center of gravity and center of lift in the hanger. (Those are the buttons in the lower left.) A good airplane will have the CG forward of the lift center, but not by too much. Getting those backwards could cause the behavior you describe.

[RSF77]

I don't think drop tanks qualify as a "stage" in the same sense that it does a rocket launch vehicle, even if they do have intakes. It just so happens that in KSP even some minute things can only (or conveniently) be taken care of in the staging sequence, there are plenty of ways to jettison things without the use of stages if you want to get that nitpicky about it. Plenty of "SSTOs" in ksp use staging to drop tanks or whatever else, in the real world I don't think this would really be considered an actual staging event like cutting a rocket in half.

Adding intakes to drop tanks is actually a good idea within the context of the game I think, maybe not so realistic but I hadn't thought of it yet. I might have to take the extra step in putting a jet engine on the same drop pod just to convince myself that I'm not cheating.

Also to OP, speaking of cheating, I usually spam reaction wheels all over my ssto designs to ensure maneuverability within a certain amount of reason. Aerodynamic flight in ksp seems to still be a WIP so a workaround here and there isn't against the rules, hell... nothing is... its a sandbox game, do what you want.

[horndgmium]

I think the fact that they're detachable doesn't automatically make it not an SSTO -- do you require dropping the tanks to get to a stable orbit? Still an ssto if you deplete the fuel but hold onto the tanks. Also, is it possible to get the ship to orbit without pulling much of the fuel from the drop tanks?

Edit: plus, the drop tanks don't have engines do they?

[Capt. Hunt]

Actually, my mistake. The detachable tanks are indeed fuel-only tanks. And okay, so its actually a TSTO, if you want to argue semantics. I was hoping for some input on the flippy-floppy, almost uncontrollable unpowered flight. It does not glide at all. In fact, given its way, I think it would land tail first, based on its tendency to flip over at low speeds.

One idea I was thinking of was using Infernal Robotics to build F-14 Tomcat style wings that I could reposition when needed. Anybody have a better idea?

I could be wrong, but I don't think the stock aerodynamics would take the wing position into account. Besides, those wings move to allow for better maneuverability when slow while also providing less drag when fast, I don't think that's a problem you'll run into on a launch. You might just want to try larger wings for more lift.

[neamerjell]

I could be wrong, but I don't think the stock aerodynamics would take the wing position into account. Besides, those wings move to allow for better maneuverability when slow while also providing less drag when fast, I don't think that's a problem you'll run into on a launch. You might just want to try larger wings for more lift.

Launching is no problem, except it takes the entire runway because my rear landing gear are so far back to prevent tail strikes. Landing is dang near impossible. I thought of a swing-wing setup to reposition my center of lift vs my center of mass on the fly.

[KeithStone]

Doing swing wings with infernal is difficult on anything that size due to the fact that the infernal parts can wobble quite a bit unless you put quite a bit of effort in to getting things strutted just right in a way that wont cause the physics to go all explodey on you. I would say the first thing you might want to look at instead would be TAC fuel balancer, if your COM is drifting during flight you can balance out all your fuel and keep it (mostly) constant, as long as you have the same percent of fuel both in front and rear. You can turn "balance all" on for both liquid and oxy at launch and it will stay on through your whole flight as long as the craft remains focused.

[neamerjell]

Doing swing wings with infernal is difficult on anything that size due to the fact that the infernal parts can wobble quite a bit unless you put quite a bit of effort in to getting things strutted just right in a way that wont cause the physics to go all explodey on you. I would say the first thing you might want to look at instead would be TAC fuel balancer, if your COM is drifting during flight you can balance out all your fuel and keep it (mostly) constant, as long as you have the same percent of fuel both in front and rear. You can turn "balance all" on for both liquid and oxy at launch and it will stay on through your whole flight as long as the craft remains focused.

This is exactly what puzzles me; the front engine mount, turned around and used to mount the intakes and cockpit, and the two auxiliary tanks underneath are the only fuel and oxidizer I have - and the two under-slung tanks have fuel lines pumping to the center tank like asparagus staging, so if anything, the weight pretty much stays up front. If you look at the final screenshot, you will see that I still have about half my fuel left at landing, and it still wanted to flip. I'm gonna go into SPH and drain the fuel tanks completely and see where my COM is. I will report my findings soon.

[neamerjell]

Solved my problem of low speed instability! I drained the fuel down to half and the COM moved WAY behind the COL! I was very surprised. I had to use 10T worth of Lack Luster Labs counter weights on the nose to compensate, and moved my drop tanks to the very rear.

To answer horndgmium's questions: Do I require dropping the tanks to get to orbit? No, but I end up using a third of my rocket fuel to get the last 15km. I usually drop them to shed the extra mass and drag. I totally drain the drop tanks by the time I switch to rockets at about 25-27km, they are for getting me into the upper atmosphere and leaving the main fuel/oxidizer tank for rocket only use. My original intention was to be able to take this thing to Minmus and back, or at least the Mun. And the drop tanks have NO engines, just extra intakes.

Edited May 6, 2014 by neamerjell

[LvL]

Technically, if you dropped the fuel tanks WHILE in orbit, it would still be a SSTO because single stage to orbit doesn't have anything to do with staging WHILE in orbit. WHILE is a very nice word.