Jet to space!

[JenBurdoo]

Launch a ship into space using air-breathing engines only, ie any engine(s) that conks out around 30km. This means you have to be going as fast and as light as possible when the oxygen gives out. As an example, the above pic shows a four-piece aircraft that I coaxed to 166km. I got another one to 179km. My first try didn't even have a parachute, and suicide-burned just before landing to save the pilot.

- No rockets, no RCS, and no hybrids (RAPIER, etc).

- Control mods like MechJeb are fine.

- Multiple engines are fine.

- Post images of your craft at launch (proving you didn't use rockets to get it into space) and at apoapsis.

- Does not have to land on a runway, or even intact.

- The intent is to suborbit - just get as high as you can. But if you CAN orbit, all power to you.

- No fair letting Jeb get out at apoapse and push.

Category I (the one I'm doing, as I haven't tried FAR or unstock parts yet and have had zero success with light probes thus far:

- Stock aerodynamics and parts.

- Must contain a Kerbal.

- Kerbal must survive.

Category II

- Anything goes. Aerodynamics, modded parts, probe-cores, no recovery, whatever you like. Extra kudos for getting into orbit, or smacking into the Mun.

Edited September 25, 2014 by JenBurdoo
Pic too large.

[MarvinKitFox]

You are doing the bunny-hop out of atmosphere version of "orbit" there. Kind of similar to what the guys at Virgin Galactic are doing with their SpaceShipTwo craft.

Using just Turbojets in stock KSP, I can achieve an "orbit" of about 30x250km

I think some of the demi-gods here can take that to true orbit by such exotic techniques as trapping air in closed-but-full air intakes, etc...

Pretty sure I saw a post like that from Kasuha, for example, but I cannot find it just now.

[Rhomphaia]

You are doing the bunny-hop out of atmosphere version of "orbit" there. Kind of similar to what the guys at Virgin Galactic are doing with their SpaceShipTwo craft.

Using just Turbojets in stock KSP, I can achieve an "orbit" of about 30x250km

I think some of the demi-gods here can take that to true orbit by such exotic techniques as trapping air in closed-but-full air intakes, etc...

Pretty sure I saw a post like that from Kasuha, for example, but I cannot find it just now.

An old one of mine

[Sirine]

OP does not mention the craft need to be in standard-sustainable-orbit.

[JenBurdoo]

OP does not mention the craft need to be in standard-sustainable-orbit.

That's right. I'm sure it's possible, but atm all I've been doing is suborbital, just trying to get as high as possible.

[KerikBalm]

Launch a ship into space using air-breathing engines only, ie any engine(s) that conks out around 30km.

Intake spamming can get you a lot higher than this... although at 50km, you won't be producing much thrust.

- The intent is to suborbit - just get as high as you can. But if you CAN orbit, all power to you.

While I haven't tried storing intake air, I can easily get a perapsis in stock, above the ground, and an apoapsis that was quite high (200? or so)

Category I (the one I'm doing, as I haven't tried FAR or unstock parts yet and have had zero success with light probes thus far:

FAR/NEAR (I use NEAR)nerf jet engines, making it much harder (they seem to top out at about 1750 m/s, and their TWR is much lower)

If I were to try this challenge, I would "cheat" - ie take advantage of a loophole:

You never specified that this has to be done from Kerbin - hehehe

I'd start from the surface of laythe.

Orbital velocity there is ~1875 m/s, and with jets, you can easily reach 2,000 + m/s -> It is quite easy in full stock to get to orbit there on turbojets alone.

[Pds314]

Hypothetically, it should be possible to get pretty high, in stock aero, maybe 500 km up. With KSPI, you could go to interplanetary space, considering that in RSS, I've gotten to over 5000 m/s with nuclear thermal turbojets. Of course in stock, there is always Infiniglide, which can reach 6 km/s or more.

[Yakky]

That's right. I'm sure it's possible, but atm all I've been doing is suborbital, just trying to get as high as possible.

Getting into a true orbit (i.e. periapsis above the atmosphere) is very tricky because it requires delta-V to be expended at or above the periapsis height. Put differently, it's not physically possible to achieve a 70km periapsis without using something to add prograde thrust at or above 70 km. (If you don't believe me, try it. Design any rocket you like, shut off all engines below 70km, and see if you can get a stable periapsis over 70km.)

This is not to say an orbit is totally impossible. There are a couple strategies that might work:

(1) As others have suggested, you could shut down some air intakes while still in the atmosphere to trap a precious little bit of air that could be used later up in space to restart the engines for a small circularization burn.

(2) If you could build a jet craft sufficiently fast to coast all the way out to the Mun, you could use a gravity assist slingshot around the Mun to circularize your orbit at a nice high altitude. (This was a very clever strategy pioneered by QuesoExplosivo on my recent Hands-Free Mission Challenge. See http://forum.kerbalspaceprogram.com/threads/94490-The-Hands-Free-Mission-Challenge?p=1432732&viewfull=1#post1432732 and look at the cool trajectory change in the 3rd picture.)

(3) The rules don't seem to expressly forbid having Jeb get out and push. Once you're already up in space, the small thrust of his spacesuit maneuvering pack could easily put the finishing touches on an orbital trajectory. (But this might be considered cheating.)

Edited September 25, 2014 by Yakky

[JenBurdoo]

Edited to forbid having Jeb get out and push. Though I think I did mention no RCS.

You can trap air to use again in space? Really? I'll have to try that... possibilities abound.

[Yakky]

You can trap air to use again in space? Really? I'll have to try that... possibilities abound.

So they tell me. I've never tried it either. Not sure how much you get.

[JenBurdoo]

How do you do it? I found shutting down the intake before launch (using the little green button to the right of the tweaking menu) saved a small amt of air, but unclicking that in vaccum didn't seem to do anything at all.

[Pecan]

"Canned air" is just that. You can, very briefly, run jets on the air that is contained within the closed intakes (shutdown jets and close intakes before leaving atmosphere, reactivate jets once at apoapsis, or wherever). Another trick would be to use the force of a decoupler to give your ship that final orbital push.

[No one]

I did this a while ago for another challenge, which was almost exactly the same as this but was judged on Periapsis rather than Apoapsis and didn't require a Kerbal.

I submit this in category 2, because it doesn't have a Kerbal. Other than that, everything's normal. All stock, no aerodynamics exploitation:

Apoapsis: 253,066

Periapsis: 167,780

Launchpad:

Orbit:

Mission Report:

It probably wouldn't be that different to send a Kerbal into orbit, but the ship was extremely annoying to fly so I'm probably not going to do it again.