SSTOs, need some help

[Captain Sierra]

God, I can't build these things to save my life. The Jool system hates me so I wanted to do a Lathe mission, just to show Jool who's boss (every probe sent has crashed or gone retrograde). I want to include an STOL SSTO, a seaplane (all stock ), at least one atmospheric jet, a rover, a small base, and a fuel depot. Problem is, I can't do that. I can't build an SSTO. I have in fact done it, but only once. I cannot replicate it. The Orion I crew shuttle, a problem. It can make orbit, but it barely has enough fuel to rendezvous with a station so long as it's under 200km, making it useless to ferry to my million mile high Horizon Station (1.654 million km). I need an SSTO that can reliably orbit and make it to a 250km station around Lathe, and probably some lessons on building one. The only one I have done is B9, I'd like my next one to be stock-ish.

I build SSTOs (or try to) under a few personal rules that make it look better and perform more relistically, listed below.

1) I don't air hog. If I have to use the evil little cubes or part clipping to mount them, I try to avoid it. I also try to keep no more than 2-3 intakes per engine (have gone as high as 4 before).

2) I try to avoid wing stacking. I don't like biplane designs or clipping a second wing into the first. I find it unrealistic an aesthetically unpleasing because of the resulting texture glitches.

3) No NERVAs in atmosphere. I don't want to irradiate planets. I never use NERVAs on landers or anything that flies in atmosphere.

Under that set of restrictions, can anyone build something that I can dissect to learn or otherwise help me? I try to avoid part clipping on tanks and body panels, but will do some clipping to make badass looking wings.

[Moar Boosters]

Can I ask why you don't airhog? If you don't have enough intakes you won't be able to fly hypersonic using only jet engines and are going to have difficulties getting into orbit with any kind of efficiency.

Assuming it's for aesthetic reasons, the blended wing body is the best solution I've found for hiding air intakes. It gives you massive amounts of wing surface and lift, and allows you to hide all the intakes inside the plane where nobody can see them. My constuction is slightly ghetto and has some wing overlapping, but thats not inherent to the design and can be avoided completely.

Inside this thing, I've hidden about a billion radial intakes. You don't need to use the cheat menu to place them, the game lets you place them practically anywhere already.

[Captain Sierra]

I don't air hog as a personal thing. I find it destroys realism. I can in fact make planes that can fly at 23km and 1200m/s without air hogging, but these were high altitude research planes, not SSTOs.

Remember, I'm not KissShot, I don't build massice epic things like that.

UPDATE: My use of radial intakes is limited to realistic appearances. Here is the Orion, the only one I ever made that worked.

Edited September 28, 2013 by Captain Sierra

[Moar Boosters]

Did you see scott manley's spaceplane video?

The slightly modified aeris 4a could easily take off and rendezvous at 200km orbit on laythe.

First thing would be try and replicate what Scott does in this video, then try and build a similar plane from scratch.

[Captain Sierra]

I have attempted to apply the lessons there to this and thusfar, with minimal success. SSTOs are really not my thing, which I hate because getting one that works is so satisfying when the magnetics kick in and you pull in for that perfect dock.

[KissSh0t]

You are going to have a hard time trying to achieve what you want to achieve without using more than a few Air Intakes.

Treat them like you do fuel tanks.. build an engine out of them, make it internal and you will be on the way to better achieving your goal.

It's like.. the jet engines for instance.. where are the actual engines??? all we can place is a nozzle... wow that is so realistic.

You build your craft and make it how you want.. if you can do it stock then more power to you.

A little tip would be to create an aircraft that can fly up to at least 30KM and possible higher on Jet Engines then go for speed... as fast as possible, you can actually circularize an orbit in atmosphere without cheating... it just takes making a very fast aircraft.. you save a lot of fuel this way instead of pushing yourself up most of the way with rocket engines.

If you can get most of the speed from Jet Engines, then bump yourself out of atmosphere with rocket engines then you are doing a good job.

[Captain Sierra]

One of my high altitude jets. Note it still obeys the 4 intakes to an engine requirement I have set myself.

This is what it can do. Speed is pretty topped out but I could probably push it a bit faster and a ways higher. I still have enough air to go higher.

Proof that this request is not beyond unreasonable. The problem is these jets are so good because of weight, or rather lack thereof. Add a few rocket fuel tanks in the mix and things get heavy quick.

EDIT: another thing to note is that the Orion, pictured a few posts ago, has about 3 intakes per engine and it can make orbit.

Edited September 28, 2013 by Captain Sierra

[Moar Boosters]

Airhogging planes aren't out of the bounds of realism. They're effectively just very efficient scramjets. The SR-71 could fly at 25,000m and that was designed 40 years ago. Hell, the Skylon is supposed to have a magical engine that is both an airhogging jet and a rocket combined together.

Having a spaceplane that starts its rocket burn at lower altitutes is just as unrealistic, but for different reasons. Mostly because we cant build a fuel tank that light and strong enough to hold all that fuel and not be a major burden once the plane wants to get into orbit.

[Cruzan]

So the trick to getting an SSTO to orbit without air hogging (2-3 intakes max per engine) is to get the right mix of jet fuel to rocket fuel and to select to right engines for the job. With airhogging you don't need as much rocket fuel, which ends up making the plane muuuch lighter. That's the extra benefit of hogging people don't really mention.

Absent of air hogging you're essentially making a plane that can carry you to 18km or so, then building a rocket after that. SSI's Aeon (The other SSI ) is a good example of that design if you want to take it apart. It's all rocket fuel and the amount of fuel it uses to get to 18km is pretty minimal anyway. There is some clipping in the wings, but it could easily be designed without the clipping.

Check it out! SSI's General Catalog has the Aeon right on top.

My guess is you're starting off too big with your initial designs. Get the hang of designing smaller SSTO's with your design criteria (no clipping/hogging) before you scale up to larger ones.

Good luck!

[Captain Sierra]

a plane literally built from intakes is and taht is what I am really trying to avoid here. Also, I tried to build the scott manley plane. It was unbelievably sluggish and would not climb at all. I must have done something wrong.

[Captain Sierra]

So the trick to getting an SSTO to orbit without air hogging (2-3 intakes max per engine) is to get the right mix of jet fuel to rocket fuel and to select to right engines for the job. With airhogging you don't need as much rocket fuel, which ends up making the plane muuuch lighter. That's the extra benefit of hogging people don't really mention.

Absent of air hogging you're essentially making a plane that can carry you to 18km or so, then building a rocket after that. SSI's Aeon (The other SSI ) is a good example of that design if you want to take it apart. It's all rocket fuel and the amount of fuel it uses to get to 18km is pretty minimal anyway. There is some clipping in the wings, but it could easily be designed without the clipping.

Check it out! SSI's General Catalog has the Aeon right on top.

My guess is you're starting off too big with your initial designs. Get the hang of designing smaller SSTO's with your design criteria (no clipping/hogging) before you scale up to larger ones.

Good luck!

I have been trying to go as small as I can but I think I am overengineering stuff because they always end up Ravenspear size at least. WHen I work with B9, the size problem is exaggerated.

[KissSh0t]

20KM is too low... and 1259.3m/s is too slow..

What you need to get too is 30KM while going at about 1800m/s - 2000m/s before switching to rockets or you are simply wasting too much rocket fuel.

[Captain Sierra]

20KM is too low... and 1259.3m/s is too slow..

What you need to get too is 30KM while going at about 1800m/s - 2000m/s before switching to rockets or you are simply wasting too much rocket fuel.

So says the SSTO MASTER to he who as only ever made one.

[KissSh0t]

Try making bodies out of the wings.. make interesting shapes..

Ideas for you. From my early to my newest.

[Moar Boosters]

Give the Manley plane another shot. It's not the most efficient thing, but you don't really need that much efficiency given your mission goal. Half the challenge of spaceplanes is learning to fly them, and that's a confirmed okay design which you should be able to use to learn ascent profiles. Once you've got piloting that one down, you can start adding more intakes and looking for greater efficiency and range.

[Cruzan]

Ya I first started off making mine way too big. Once I started working for SSI I got a lot better at toning down my designs. I've yet to make a non-air hogger though, but again, the Aeon by inigma shows that it's definitely possible. It has only 3 circular intakes, and 2 radial intakes, runs on 2 Basic jets to 18km, then powers the rockets to get to orbit with enough fuel for rendezvous. I think that fits your design criteria pretty well imo.

[Captain Sierra]

I think my current prototype is going to work. At about 15* angle of attack, it was climbing at about 5* and I got it to hit 24km and 1300m/s+ before I was about to flameout. I went ahead and kicked in the aerospike but my engine kill action group was messed up so only 1 engine shut off. flatspin. Gotta rework some fuel lines and redo the groups, then I can test it's ability to space.

UPDATE: So it gets to space. Currently, my ascent profile is too crappy to make it a clean orbit, but it will do it. Now I need to see how high I can make rendezvous on kerbin. Does anyone know how high I need to get on Kerbin to make a 250km rendezvous on Lathe?

Edited September 29, 2013 by Captain Sierra

[Cruzan]

Have you tried using the LV-T30 engines instead of the aerospikes? They're a little tougher to fit in aesthetically, but they make up for it with higher thrust, and less mass. Slight Isp loss, but its fairly minor!

[Captain Sierra]

I can always try it. perhaps I could go with the LV-T45s. Less power but that means won't eat as much fuel. Far as I'm concerned, the problem is not the engine, it's my choice of ascent profile. My rocket ascents are pretty inefficient. How does one go about doing an SSTO ascent profile once you switch to rockets.

[fcdrifter13]

Are you using mods or trying to do this stock?

[Captain Sierra]

I'm on my minimalistic mod install (which still has like 20 plugins I have come to not live without) which has only a handful of parts mods, but I am not above using them. Ones that I am using is the RLA stockalike RCS thrusters to make RCS control easier.

[fcdrifter13]

If you are using p-wing a single jet engine stacked ontop of a rocket engine (i used a -45) got me to orbit. It was a U2 design with a large wing span and very little weight. I really didnt think it was going to go full ssto so I didnt have an rcs so getting home was a chore. I do think that intake spamming helps but is not needed, I collect all of my speed at lower altitudes and carry it up with me on a 15* attack angle and switch to rockets after .8 intake air is on the bar. I think that is the biggest hurdle, getting my mind past the needing altitude all of the time, it is about orbital speed. With FAR it makes it very easy and you can get a moon intercept at 30k on kerbin and just hold the throttle full until you get to the end of the atmosphere.

[Captain Sierra]

so, 15* AoT slowly gets you out of atmosphere, max efficiency. Will try that.

EDIT: I don't have P-wing on this install and I try to avoid engine clipping. for me, it usually makes stuff blow up.

Edited September 29, 2013 by Captain Sierra

[ssTALONps]

You might find my ARX-3 suits your need for a more realistic, non-airhogging SSTO.

ARX-3 'Vulture'

Yes, it's kinda large (35t) for a single crew SSTO, but it has unrivaled reliability and redundant dV for all your need.

Capable of reaching orbit even with single LV-T30 running all the time, the ARX-3 is ultimate multirole SSTO.

-No turbojet and intake spam, because why use intake spam and OP turbojet when you can make more-than-competitive SSTO out of UP basic jet and 1:1 intake to engine ratio?

-With easy and efficient ascent profile, you'll have 850~950m/s of dV after 80x80km orbital insertion. Lower time to orbital insertion is bonus.

-Emergency rescue mission? No problem. Just spark that LV-T30, pull up to 90 deg and hand it over to MechJeb ascent autopilot. 300m/s of dV after 80x80km orbital insertion guaranteed.

-Talk about 'STOL' and 'maneuverability'... Fighter based design speaks for itself.

-Excellent cross range performance with low landing speed.

-Properly shielded propulsion systems for future reentry damage update.

-NERVA equipped version (ARX-3N 'Voyager') with even more dV available, although I consider it to be inferior then original design.

As you'll gradually realize, the ARX-3 is not a typical SSTO design; it probably won't help you design turbojet-based, more conventional SSTOs.

However, I think it'll be worth a time to think about alternative designs.

And here's screeny showing ARX-3 after 91x91km Laythe orbital insertion after taking off from equatorial base...

Well, 1.6km/s of dV was just too surplus for a simple crew rotation mission, so I used it for surface-to-orbit refuel mission using HOME mod.

[Moar Boosters]

I think my current prototype is going to work. At about 15* angle of attack, it was climbing at about 5* and I got it to hit 24km and 1300m/s+ before I was about to flameout. I went ahead and kicked in the aerospike but my engine kill action group was messed up so only 1 engine shut off. flatspin. Gotta rework some fuel lines and redo the groups, then I can test it's ability to space.

UPDATE: So it gets to space. Currently, my ascent profile is too crappy to make it a clean orbit, but it will do it. Now I need to see how high I can make rendezvous on kerbin. Does anyone know how high I need to get on Kerbin to make a 250km rendezvous on Lathe?

If you can orbit on Kerbin you should be able to reach that rendezvous on laythe. It's atmosphere only starts around 55k.