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Hey all.. I'm trying to send this SSTO into another planet. It has 4 Turbojets and 1 Nuke for efficient transfers. Also a science vessel in the front with a Kerbal seat.

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The undockable vessel is not working properly though on my test run to Mun, can't seem to get the balance properly yet.

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http://cloud-3.steampowered.com/ugc/3334091192339666004/E0989882B00F1502911C176EACF656A57EB0FDE6/

Here's my new crew transfer SSTO, its not too special I guess.

It was mostly built with looks and realism in mind, so its really just limited to Kerbin orbits under 150,000m

Good looking craft there, a couple of questions.

Does it have matching engines under the wings to match the top mounted ones?

And are you using FAR and DRE?

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My SSTO: the Safiran Space Program G-Hawk 'Endurance'. ("G-Hawk" is short for Gravity Hawk.)

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This was my payload test mission. It was carrying a Minmus rover, which is roughly 1/3rd the size of its cargo bay. Endurance reached orbit with that payload with 1600 units of liquid fuel to spare.

I haven't yet fitted external docking ports to it, though I do plan to.

Download Link:

http://www.sendspace.com/file/mk5sye

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@RedDwarfIV Do you have balancing issues with having 6 lower and 4 upper... Turbojets I mean... Especially at high speed?

It's six and six. I guess I have my screen brightness higher than you do.

They're basically fitted to bi-couplers that have been rotated 45* so that the spacecraft doesn't need such tall landing gear. Which is a good thing, since the taller landing gear it used to have started bending around when I put payloads on board.

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It's six and six. I guess I have my screen brightness higher than you do.

They're basically fitted to bi-couplers that have been rotated 45* so that the spacecraft doesn't need such tall landing gear. Which is a good thing, since the taller landing gear it used to have started bending around when I put payloads on board.

Ahh.. now that you have mentioned that I can see the engines... wow to me at first it really did look like 6 lower 4 upper...

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Keep throttling down at 30-32km and introduce your rockets when your acceleration stops. Keep creeping higher and throttling down to get the most speed possible before killing your turbos and angling back to 45 degrees at full throttle.

This is basically what I've been doing. At 50% throttle, my speed starts dropping if I keep increasing my pitch to maintain vertical speed.

You can also try a dipper kick-out maneuver. You will need more elevons for that though.

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Holy cow, how does that even work? I'll have to try that with all my SSTOs.

It's about momentum shifting. You take your horizontal speed and turn it into vertical speed while putting on more vertical and horizontal at the same time. You pick up that lost horizontal speed when you get higher up.

When you descend you will have more energy than you could ever have at a given altitude because of your momentum. Then, when you kick up, you get alot of traction from the available air and the fact that your turbines will be in a high thrust output altitude. Lastly, your wings will supply you with a huge amount of lift when you are kicking out all the way up to 40km, simply because of the combination of high speed, dense air and high angle of attack.

So, on that last point. Moar wings if you are going to do that maneuver. I've found that wings are not important on an SSTO up 20km, then they start to get very important for fuel economy.

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This is basically what I've been doing. At 50% throttle, my speed starts dropping if I keep increasing my pitch to maintain vertical speed.

You can also try a dipper kick-out maneuver. You will need more elevons for that though.

I just tried this. At 30 km, I stopped pitching up, then pitched down to zero, let the plane descend about 2500 meters, then pitched all the way up to 45 degrees and ran the engines in jet mode until the vertical speed stopped increasing. Result: 100 km LKO with 200 m/s remaining, which translates to a saving of 300-400 m/s on the ascent. Incidentally, it had no trouble with pitch authority.

Holy cow, how does that even work? I'll have to try that with all my SSTOs.

Are there any other design tips you can think of besides "10-15 turbojets per ton, more wings, more intakes" to improve the payload fraction of SSTOs?

That works by getting you closer to your final airbreathing speed, then switching to rocket power with enough vertical velocity so drag doesn't hurt you too much on rocket power. The same thing can be achieved with proper vertical velocity management, BTW, only the perfect run is, of course, difficult to achieve, much less get consistently. Good idea to pack a reserve in case you don't nail it. Lots of people just don't know how to milk their designs, though... as a rule of thumb, I usually do a run ascending at 10m/s or less until I can't go faster to find out just how high and fast I can get on that particular design, which depends mostly on intake ratio and secondarily on T/W ratio. Then I try to copy that ascent... only getting to the final point with >100m/s vertical velocity, and leveling off for the speed run as late as I can, with perhaps even a small dip get enough time for accelerating before committing to the final ascent... but my best ascent never have the dip, that usually happens when I screw up and get up too fast.

The important thing is to manage to go pretty much horizontal very close to your maximum flight altitude for long enough to get close to steady-state condition (i.e: drag equals thrust), therefore getting the most out of the air. People usually run out of air long before that, transitioning to rocket power before they get even close to their limit because they climb too fast. Or when they learn a bit more, by the time they do reach maximum velocity they are still horizontal and have to build up vertical speed on rocket power, which is inefficient (you are curving you trajectory upwards, actually, therefore working against some of the work you did on jets). And it's pretty damn hard to balance the two.

Oh, and running your rocket at the same time as your jets when you start to throttle down can give you a very fast ascent speed very efficiently, so as a rule of thumb I pretty much always turn them on when flameout force me under 50% thrust, and I keep the jets on until at least 30% throttle, by which time you are usually losing vertical speed and need to turn them off to throttle up and close the intakes. So yeah, hope you are doing it that way (if you can! that is a trick that doesn't work on RAPIERS).

In the real world you could use a dip-and-pull-back maneuver to get to a higher speed than would be possible otherwise (and the maneuver is used operationally by military planes, BTW), but that relies on aerodynamic lift to convert potential energy into kinetic one, and frankly, given KSP's aerodynamic model and the fact that wings pretty much offer no lift at the altitudes we are talking about... Unless you have Ferram Aerospace, expect that maneuver to cost you delta-v, not save you anything.

Rune. So basically, knowing your SSTO, and loads of practice. The good part is everyone gets better with time!

Edited by Rune
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Yeah, I use kick-out maneuvers frequently as well, and you are right, it is very design-specific. Designs with great thrust to weight ratios seem to be the easiest to manage up there, and respond the best to attitude changes, but they are the ones that benefit the least from the maneuver. Basically they have enough performance to just do a vanilla ascent. The main advantage just seems to be getting to your air-breathing max speed, and thus really milking the efficiency of the jets.

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Refueling in orbit seems to be easier than worrying about getting max efficiency on a climb out. Also can use tweakables and launch with non full tanks, then your T/W goes up on the same design and your accent is easier to manage.

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Go flight?

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Think I need to work on that one a bit :/

Here's a basic one I created under FAR to launch satellites & probes.

It does reach orbit on its own in one stage. The decoupler remnants on the top are for an optional droptank I use to have more fuel once in space.

I tend to underestimate the value of small cargo.

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Edited by Immashift
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I have rebuilt an old SSTO completely from scratch.. you can see the original of this craft in the first post of this thread orbiting Duna.

During it's first test flight I circularized Kerbin using only Turbo Jets at 37,000... This aircraft is very very fast when it is above 20,000.

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Pretty simple design I started working on. Was impressed with the speed it gets even right after takeoff. Granted it's under FAR, but still. :P

The idea is that a Rapier can help during ascent as well as after takeover, whereas an LV-909 or whatever would just sit there. Granted the turbos sit there after takeover, but.. I like them :)

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I'm still having problems designing heavy cargo planes though.

Edited by Immashift
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Docking with my nearly empty SSTO Fuel Station.. I really need to figure out a way to get Big Red fuel tanks into orbit and docket to this so I have more fuel.

After refuel I think I will try going to Duna again... I say try because I am not very good at getting to other planets : T

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