ARX-3 / ARX-3N - Realistic, Versatile SSTO [ASX-II EURS Update!]

[ssTALONps]

Intro

DOWNLOAD - Spaceport

v1.0a Updated instruction for use in conjunction with F.A.R. mod on Spaceport!

v1.1 ARX-3B 2 seat shuttle updated!

v1.2 ASX-II Exo-planetary Universal Refuel System updated!

One of the most successful designs of Aircraft Research eXperiment project (yes, I know it’s boring acronym), the ARX-3 / ARX-3N is a 35t class medium sized SSTO that is capable of Munar low orbit insertion and return, depending on version.

With unmatched versatility, realism and reliability, these remain one of my favorite SSTOs of all time. While they do have inferior performances when compared with world flooding with intake spamming, turbojet powered high performance SSTOs and nothing to stand out in performance aspect, nevertheless they’re designed with both realism and reliability in mind and will go where you want to go!

Overview

The ARX project started out as an ambitious project to design more realistic, reliable and most importantly, sustainable (compatible with future updates) SSTOs. Key design features include:

1. No intake spam – This is just ridiculous…

2. No turbojet engine – I anticipated worst case scenario nerfing of turbojet rendering it obsolete.

3. Wings must have low AR – Taking structural integrity into consideration.

4. Vital components must be protected – For when reentry heat damage gets added.

5. 80x80km orbit insertion within 10 min. – Rapid orbital deployment for faster rendezvous.

6. Ground refuel capable – Total re-usability, you don't call something a SSTO when it can not be refueled after landing!

7. Reliability – Easy to fly and must have almost same dV after orbit insertion.

This unique design philosophy resulted in many interesting design. Many of these designs, however, were merely experimental ones and could not meet all of design goals, although some showed promising performances. This included a design inspired by ARCA’s IAR 111 ‘Excelsior’ supersonic mothership. With further modifications incorporated, the ARX-3 finally came into light.

ARX-3 'Vulture'

The ARX-3 ‘Vulture’ is versatile, yet easy to fly SSTO capable of reaching prograde orbit over 500x500km, or if the need arises, polar and retrograde orbits. If flown right, it will have around 850m/s of dV on orbit after ascent. Even though I expected significant reduction in performance as a result of abiding harsh design guidelines, the ARX-3 is more than capable of most ordinary SSTO designs.

As it completely relies on auxiliary rocket engines (4x 24-77) and main rocket engine (1x LV-T30) for main orbital insertion burn, you’ll find its ascent profile more of a rocket then a space plane. This was essential as it permits rapid deployment time nearing that of rocket.

It has one inline docking port for ordinary docking operation and two small docking ports intended to be used as refuel ports; they’ll perfectly match with ASX series refuel trucks (included in download). If you’re a big fan of ‘SSTOconomy’, you can use single ARX-3 over and over again for refuel mission.

For unmanned shuttle missions, it’s equipped with hidden unmanned probe and RTGs for unlimited operation. You’ll never, ever run out of electricity!

The maneuverability of this SSTO is actually quite great. You can fill it up with liquid fuel after landing and use it as low altitude high maneuverability jet fighter. It will also glide gorgeously after reentry, making approach glide easier.

On limited occasions, the ARX-3 can be used as a payload launcher with maximum payload around 3t, though it’s not designed with payload delivery in mind. While attaching payload on top of fuselage is possible (as seen on top screenshot of thread showing sat launch version), I do not recommend it as it will result in gradual pitch-up tendency. Recommended payload attaching point is beneath the main wing symmetrically.

ARX-3N 'Voyager'

The ARX-3N ‘Voyager’ is a further development of ARX-3. As the suffix ‘N’ suggests, it replaced LV-T30 with LV-N, almost doubling its dV on orbit after insertion. With optimal ascent, you’ll have 1.5km/s to 1.7km/s of dV, enough for Munar / Minmus low orbit insertion and return.

To compensate for low TWR of LV-N, it adds additional 2 pair of 24-77s, relying initial ascent on those fuel-hungry engines. This is unavoidable as all of the ARX series does not accelerate into orbital speeds within upper atmosphere.

When fully fueled up, it has dV exceeding 8km/s meaning it can be used as interplanetary transport, although I don’t use it for that; let’s think of our poor kerbal caged for months and years within crampy cockpit

It maybe a little bit cheaty as I clipped one fuel tank inside of LV-N but overall fuel capacity is same. The extra fuel tank was necessary to provide attachment point for parking gear and lower wing.

ASX-II EURS refuel truck

The ASX-II Exo-planetary Universal Refuel System is intended as primary surface refuel system for outer planets, especially Laythe, as requested by Tada.

As the acronym suggests, it's designed from the beginning to have universal refuel capability for light to medium SSTOs. You just have to attach Clamp-o-Tron Jr. like ARX-3 does. Don't worry, it's extremely simple!

It's all stock and has integrated Interplanetary Stage / Heat Shield (IPSHS) for more reality and self-propelled injection burn. With on-board fuel, it has 2.9km/s of dV, enough for Laythe transfer.

The ASX-II is supplied with dedicated launcher, fairing and heat shield system.

At launch with fairings, it has part count of ~350, which will pose problems for low to medium spec PCs but once in orbit you'll find it hardly ever causes lags.

Since it lacks skycrane and relies on parachutes for landing, you can't use it on non or low-atmospheric environments. Even with all those parachute-spams, you still have to deploy landing gears for shock absorbing or all rover-wheels WILL burst.

Within full sunlight, maximum cruise speed is around 20m/s and at night it drops under 14m/s, which is still manageable. The handling characteristic is quite good for such a large (35t) truck.

I strongly recommend using ISRU mods like Kethane or HOME mod as IPSHS uses almost all of on-board fuel. After all, it's always a better idea to have ISRU system. If you're 'purist' though, you can always attach interplanetary tug behind IPSHS and let it do the transfer, conserving fuel supply of ASX-II.

Note that actual appearance of ASX-II is slightly different from screenshots as I'm too lazy to take up-to-date screenshots

All in all, both the ARX-3 and ARX-3N are highly versatile, multi-purpose SSTOs. While I generally prefer ARX-3 over ARX-3N owing to more ease of operation and realism, you’ll find both of them useful.

The ASX series refuel trucks will make any SSTO to have refuel capability, providing total reusable fleet of SSTOs.

For flight instructions, please see ‘How to use’ tab on Spaceport.

Have fun with these!!!

Edited May 16, 2013 by ssTALONps

[oggylt]

looks simple and neat

[Darth Lazarus]

i wouldn'T say, that it is cheating with the fueltank. just pretend the fuel is stored in the wings or other fuselage ^^ (/like i pretend the extrafuel in my R-7's xD)

a very goodlooking ship.

[ssTALONps]

looks simple and neat

Thank you!

i wouldn'T say, that it is cheating with the fueltank. just pretend the fuel is stored in the wings or other fuselage ^^ (/like i pretend the extrafuel in my R-7's xD)

a very goodlooking ship.

Well, it's one of main reasons I prefer ARX-3 over ARX-3N as it's normally impossible to attach it.

I'm glad you like my design! I really like your Soyuz rockets

[SecondGuessing]

I really like these. While it's fun sometimes to see some incredibly intricate designs, these have an elegant and functional simplicity that's very endearing. Plus is nice to see a very reliable and powerful SSTO that doesn't use intake spam. Bravo, good sir!

[Flixxbeatz]

It's small

Congratulations. You're now a full-fledged professional KSP player.

[Tada]

Well... Hands down propably best SSTO I flown to date... I gave it a spin and here are my impressions and questions:

Question(s):

1. Is your style of ascent suggested in "How to use" really most efficient, why not to use shallow ascent when you get as much speed as you can using jets and then pitch up and fire rockets?

Impressions:

1. Great amount of lift results in very low take off/landing speed which makes it easy to land.

2. Good supply of fuel when in orbit.

3. Refueling the last fuel tank which is buried in the hull is on verge of impossible when docked to a station (camera angle shifts and makes very hard if impossible to select that tank), thats propably my only objection

4. I love it´s "clean" and realistic design.

5. The fact you thought of ground refueling is great.

6. Vulture exactly fits requirements of PROJECT Babylon:

"13. Space shuttle “Falconâ€Â

Goals: Transfer of crew and supplies between space station “Saphire†and surface of Laythe

Requirements: Possibility to fly between “Saphire†and surface of Laythe, if possible to be able to refuel on Laythe, preferable ability to carry crew of more than one"

Now just figure out gow to get it to Layhte. Keep up the good work!

[ssTALONps]

I really like these. While it's fun sometimes to see some incredibly intricate designs, these have an elegant and functional simplicity that's very endearing. Plus is nice to see a very reliable and powerful SSTO that doesn't use intake spam. Bravo, good sir!

It's small

Congratulations. You're now a full-fledged professional KSP player.

Thank you! I'm actually quite surprised by community's reaction toward my simple design!

Well... Hands down propably best SSTO I flown to date... I gave it a spin and here are my impressions and questions:

Question(s):

1. Is your style of ascent suggested in "How to use" really most efficient, why not to use shallow ascent when you get as much speed as you can using jets and then pitch up and fire rockets?

Impressions:

1. Great amount of lift results in very low take off/landing speed which makes it easy to land.

2. Good supply of fuel when in orbit.

3. Refueling the last fuel tank which is buried in the hull is on verge of impossible when docked to a station (camera angle shifts and makes very hard if impossible to select that tank), thats propably my only objection

4. I love it´s "clean" and realistic design.

5. The fact you thought of ground refueling is great.

6. Vulture exactly fits requirements of PROJECT Babylon:

"13. Space shuttle “Falconâ€Â

Goals: Transfer of crew and supplies between space station “Saphire†and surface of Laythe

Requirements: Possibility to fly between “Saphire†and surface of Laythe, if possible to be able to refuel on Laythe, preferable ability to carry crew of more than one"

Now just figure out gow to get it to Layhte. Keep up the good work!

I'm glad you liked my design!

Now answering to your question:

The ascent profile I provided is almost identical as ordinary rocket ascent profile, and maybe not the most efficient ascent.

Like you said, one might think it'll be more efficient to accelerate with jet engines; however this only applies to turbojet engine SSTOs.

This is because, unlike godly turbojet engines, basic jet engines does not generate enough thrust at altitudes above 9km to sustain jet engine only ascent.

It's maximum speed with full throttle at operational ceiling of 9km is only around 200m/s and at this altitude, air is dense enough to slow down you a lot, I mean, A LOT.

So it'll be a wise decision to pitch up and ignite rocket engines to quickly get out of lower atmosphere, not to mention to minimize loss of dV to basic jet engines consuming fuel with low specific impulse.

I found it while testing ARX series that once you do not use turbojets, you'd better pay more attention to vertical speed as well as pitch angle then orbital speed at altitudes lower then 20km because the atmosphere only slows you down.

Thus the design of ARX-3 is basically, as I preferably call it, 'Rocket on a wing'

I found #3 of your impression quite a nasty problem to solve and haven't found a craft-wise solution

You'll have to rotate the camera with arrow keys to avoid deselecting last fuel tank when performing refuel mission.

If you're planning to use ARX-3 and/or modify its design for your amazing project, you're welcome as long as you credit me as original author!

I'll keep a eye on your project!

[Tada]

Ok, I didn´t know about properties of basic jets - I don´t use them much.

Well, plan to deliver batch of your SSTOs to Laythe as soon as possible, then I´ll begin field trials and decide. Your craft has advantage that it can refuel on ground, which makes it practical even as an atmospheric flyer able to travel between two spots on surface. But I´ll have to come up with solution how to get those fuel trucks to airfield on Laythe. Probably I´ll add 2 big docking ports on them and it will go like that - fuel truck gets into orbit using it´s own ascent stage, in orbit it is grabbed by small space tug called "Bee" and docked to dropship going to Laythe, dropship lands on Laythes surface and drops fuel trucks on surface. I think that dropship will be able to carry 4 of them easily.

Just a small suggestion - what about 2 seater version? That would wastly improve its potential as an SSTO surface to orbit taxi

[ssTALONps]

Ok, I didn´t know about properties of basic jets - I don´t use them much.

Well, plan to deliver batch of your SSTOs to Laythe as soon as possible, then I´ll begin field trials and decide. Your craft has advantage that it can refuel on ground, which makes it practical even as an atmospheric flyer able to travel between two spots on surface. But I´ll have to come up with solution how to get those fuel trucks to airfield on Laythe. Probably I´ll add 2 big docking ports on them and it will go like that - fuel truck gets into orbit using it´s own ascent stage, in orbit it is grabbed by small space tug called "Bee" and docked to dropship going to Laythe, dropship lands on Laythes surface and drops fuel trucks on surface. I think that dropship will be able to carry 4 of them easily.

Just a small suggestion - what about 2 seater version? That would wastly improve its potential as an SSTO surface to orbit taxi

Voilà! ARX-3B 2 seat version updated!

[Tada]

Needs long runway - I hope I can find place like that on Laythe.

[darklyt750]

*Whistles* Dang, that's one great looking SSTO. So versatile and realistic at the same time, I love it. Great work

[Tada]

Landing it when it is full of fuel is pretty nightmarish

[ssTALONps]

*Whistles* Dang, that's one great looking SSTO. So versatile and realistic at the same time, I love it. Great work

Thank you!

Landing it when it is full of fuel is pretty nightmarish

Yes, the ARX-3 is not tailored for full-fuel landing unfortunately

ARX-3B's somewhat longer runway requirement is owing to CoM shift to the front.

This is inevitable, as extra cockpit adds significant weight to the front.

[Tada]

Well, it is still in the game of becoming official SSTO air taxi of PROJECT Babylon. Trials on Laythe will decide. But if solution to Laythe capable ground refueling system will be found - huge advantage for ARX-3 - it can land with minimal amount of fuel for better handling, top up and go back...

[ssTALONps]

ASX-II EURS, as requested by Tada, has been uploaded!

[Tada]

Great job, saddly I´m to tired to give it a spin today... but tommorow will be dedicated KSP day

[Wait- Was That Important?]

I've said this for one other SSTO, but this is a wonderful looking SSTO that's functional and realistic.

I lament that much of the Ship Exchange forums has become, "VTOL SSTO Seaplane and Bonus Gimmick!" I'm not saying it's all like that, and in most cases it's interesting to see how people accomplish the difficult engineering feat.

Regardless, this one's definitely for me!

[ssTALONps]

I've said this for one other SSTO, but this is a wonderful looking SSTO that's functional and realistic.

I lament that much of the Ship Exchange forums has become, "VTOL SSTO Seaplane and Bonus Gimmick!" I'm not saying it's all like that, and in most cases it's interesting to see how people accomplish the difficult engineering feat.

Regardless, this one's definitely for me!

I totally agree on that, although I'm pretty much amazed by such designs

[Rune]

Well, your "rocket on a wing" should have quite the amazing delta-v once refueled in space. It's the advantage of pure-rocket (or close to) SSTOs, that and much shorter launch times. It's the reason I quite like what came out of my X-33 replica, as well as this beautiful thing you have here. And I'd say it's perfect for someplace like Duna.

Rune. Adding tail-landing gear adds a ton of functionality, too.

Edited May 17, 2013 by Rune

[ssTALONps]

Well, your "rocket on a wing" should have quite the amazing delta-v once refueled in space. It's the advantage of pure-rocket (or close to) SSTOs, that and much shorter launch times. It's the reason I quite like what came out of my X-33 replica, as well as this beautiful thing you have here. And I'd say it's perfect for someplace like Duna.

Rune. Adding tail-landing gear adds a ton of functionality, too.

Gotta try that X-33, I always like your outstanding designs

I thought adding tail gear might ruin 'cleanness' of design. Tail strikes can be avoided with more cautious take off control.

[trippytripp]

I can honestly say, this is probably one of my all time favorite SSTO designs. It's fun to slap a small probe on top of the fuselage, or two under the wings, take orbit, then let them go and shoot them off into the Kosmos. I also love just flying the two-seater around Kerbin. And then coming back and refueling, then taking orbit. The possibilities for this plane are almost endless. Good job.

[Rune]

Gotta try that X-33, I always like your outstanding designs

I thought adding tail gear might ruin 'cleanness' of design. Tail strikes can be avoided with more cautious take off control.

Oh, I don't know if you got what I said: I mean landing legs so it can land vertically tail-first on airless worlds, nothing to do with tail strikes on takeoff (though you get a strongish part that hits before others, that can save your bacon sometimes). Sure, the look is not as clean, but three heavy-duty landing legs can do wonders once you want to go somewhere else, and they don't weight much. You know, to exploit the large pure-rocket delta-v once refueled. I've got to do something like that to the K-33, and perhaps that will be a perfect opportunity to test it out without jets.

Rune. And thanks for the praise! It is always welcome

[ssTALONps]

I can honestly say, this is probably one of my all time favorite SSTO designs. It's fun to slap a small probe on top of the fuselage, or two under the wings, take orbit, then let them go and shoot them off into the Kosmos. I also love just flying the two-seater around Kerbin. And then coming back and refueling, then taking orbit. The possibilities for this plane are almost endless. Good job.

Thank you

Oh, I don't know if you got what I said: I mean landing legs so it can land vertically tail-first on airless worlds, nothing to do with tail strikes on takeoff (though you get a strongish part that hits before others, that can save your bacon sometimes). Sure, the look is not as clean, but three heavy-duty landing legs can do wonders once you want to go somewhere else, and they don't weight much. You know, to exploit the large pure-rocket delta-v once refueled. I've got to do something like that to the K-33, and perhaps that will be a perfect opportunity to test it out without jets.

Rune. And thanks for the praise! It is always welcome

Oh, you mean by landing legs Well, since I don't use ARX-3s for non or low-atmospheric vertical landing, I normally fly without landing legs. But I think people who wants to use these for all-around landing missions or interplanetary missions will attach landing legs themselves, though I'll add some descriptions about adding landing legs for even more versatilability.

And yes, the K-33 is just simply awesome as always

[Rune]

And yes, the K-33 is just simply awesome as always

I steal from the best. BTW, I'm planning on stealing from you as soon as I get back to my gaming rig in the design of a kethane refueler truck.

Rune. Because imitation is the greatest form of praise.

Edited May 18, 2013 by Rune