Spaceplane to orbit with air breathing engines.

[RavenpawKSP]

This post is invalid. Looking back at it, I realize I didn't achieve ACTUAL orbit, just a temporary orbit, which would have died if I had cut my engines. 

Edited September 26, 2019 by RavenpawKSP
misinformation

[Samniss Arandeen]

Are you sure this is even possible? Let's see your attempt at it first. Something like this used to be possible in the older versions of KSP, but the new aero and jet engine models put a damper on airhogging and other jet engine shenanigans.

[RavenpawKSP]

Yes I am sure this is possible. I have done it before off camera but will record video or screenshots of a second attempt sometime. 

[Red Iron Crown]

Not possible with stock air breathers. You can circumnavigate but not orbit.

[JadeOfMaar]

I can almost see how this challenge can be done as I build hypersonics and have technically orbited within atmosphere, setting my Periapsis at my current position and Apopasis in space on the other side of Kerbin, but if this challenge is asking to circularize outside of atmosphere while only using jet engines, or do as I just described with stock engines, some serious, serious evidence needs to be shared in the OP or it will be easily dismissed as an utterly silly thing by everyone... And I'm using as gentle words as possible unlike some responses which may follow.

[Jefzor]

No matter how high you put your apoapsis, there will always be a part of the "orbit" inside the atmosphere at the last point where your engines flame out. So I don't think it is possible, not whithout any trickery at least (munar gravity assist or something like that...? )

 

I would love to be proven wrong (or being shown some creative tricks). 

Edited January 10, 2017 by Jefzor

[foamyesque]

I don't think this is possible in stock. Absolute cutoff speed for RAPIERs is below orbital velocities. Perhaps some kind of modded airbreather that can continue to operate up past 30km and Mach 7 would let you get an in-atmosphere orbit, but to get a stable one you're going to need thrust in a vacuum somewhere. Decouplers, Kerbals pushing, rockets, etc. Alternatively, I suppose, a sufficiently powerful modded airbreather might allow the achievement of escape velocity, which would then put you in orbit around the Sun...

Edited January 10, 2017 by foamyesque

[Red Iron Crown]

2 hours ago, JadeOfMaar said:

I can almost see how this challenge can be done as I build hypersonics and have technically orbited within atmosphere, setting my Periapsis at my current position and Apopasis in space on the other side of Kerbin, but if this challenge is asking to circularize outside of atmosphere while only using jet engines, or do as I just described with stock engines, some serious, serious evidence needs to be shared in the OP or it will be easily dismissed as an utterly silly thing by everyone... And I'm using as gentle words as possible unlike some responses which may follow.

What you describe cannot be done with stock airbreathing engines either. Even if you could run them at 70km altitude you'd need to be going ~2230m/s just to get the periapsis up to sea level, and it gets slightly worse the lower you run them.

1 hour ago, foamyesque said:

I don't think this is possible in stock. Absolute cutoff speed for RAPIERs is below orbital velocities. Perhaps some kind of modded airbreather that can continue to operate up past 30km and Mach 7 would let you get an in-atmosphere orbit, but to get a stable one you're going to need thrust in a vacuum somewhere. Decouplers, Kerbals pushing, rockets, etc. Alternatively, I suppose, a sufficiently powerful modded airbreather might allow the achievement of escape velocity, which would then put you in orbit around the Sun...

The trick from the old airhogging days might work with a modded engine: Get up to where your Ap is outside atmo, kill your engine, wait a moment or two, then close your intakes. Each intake stores a bit of intake air, which could conceivably be enough to raise Pe out of atmo.

Another option is to get going fast enough on modded airbreathers to get Ap to Mun altitude, then gravity assist Pe out of atmo.

[JadeOfMaar]

12 minutes ago, Red Iron Crown said:

What you describe cannot be done with stock airbreathing engines either. Even if you could run them at 70km altitude you'd need to be going ~2230m/s just to get the periapsis up to sea level, and it gets slightly worse the lower you run them.

Another option is to get going fast enough on modded airbreathers to get Ap to Mun altitude, then gravity assist Pe out of atmo.

That's exactly right. I know my mod parts well to use them together and to "orbit" for brief periods in atmosphere.

Interestingly, I have a spaceplane than can get an SOI change while still in atmosphere but I've never sent it to Mun. It doesn't have the TWR for landing in vacuum.

Edited January 10, 2017 by JadeOfMaar

[RavenpawKSP]

I modified one of my older planes (video below) and proved this possible. Too bad I didn't make a video of it.

Video of unmodified plane:

 

[Red Iron Crown]

29 minutes ago, RavenpawKSP said:

I modified one of my older planes (video below) and proved this possible.

Modified how, exactly?

[RavenpawKSP]

18 minutes ago, Red Iron Crown said:

Modified how, exactly?

I modified one of my older planes (video below) and proved this possible. Too bad I didn't make a video of it.

Video of unmodified plane:

I added more whiplash jet engines on the wings to achieve enough speed.

[Red Iron Crown]

1 minute ago, RavenpawKSP said:

I added more whiplash jet engines on the wings to achieve enough speed.

You did not make orbit with just stock Whiplashes, it's not possible. They stop producing any thrust at all long before orbital velocity is reached.

Do you perhaps mean that you got the plane out of atmosphere and into space? That I can see being possible.

[RavenpawKSP]

1 hour ago, Red Iron Crown said:

You did not make orbit with just stock Whiplashes, it's not possible. They stop producing any thrust at all long before orbital velocity is reached.

Do you perhaps mean that you got the plane out of atmosphere and into space? That I can see being possible.

I modified one of my older planes (video below) and proved this possible. Too bad I didn't make a video of it.

Video of unmodified plane:

I put heat shields on the sides, front, wings, etc... In positions where they don't add too much drag to withstand the heat that comes with speed that is achieved and bypassed with the extra whiplashes under the heat shields.

The highest speed achieved was 41,232 m\s, which was achieved shortly after engine flameout before it stopped accelerating during the force glide on prograde.

A few heat shields and wing parts were lost due to the heat.

But a full orbit was achieved.

Edited January 15, 2017 by RavenpawKSP

[Red Iron Crown]

12 minutes ago, RavenpawKSP said:

The highest speed achieved was 41,232 m\s, which was achieved shortly after engine flameout

Scarcely believable that you're playing an unmodified game. Please link the craft file used to achieve orbit.

You can stop linking the video of the craft that wasn't used for this, three times is plenty.

[RandomGuy1824]

Once we are in space can we get out and push to stabilize the orbit? And also is rcs counted as an engine?

[RavenpawKSP]

1 minute ago, Red Iron Crown said:

Scarcely believable that you're playing an unmodified game. Please link the craft file used to achieve orbit.

You can stop linking the video of the craft that wasn't used for this, three times is plenty.

Sorry, the video keeps popping up when I quote, and can't be deleted.

And I lost my computer when my mother died a few months ago. All my current saves and craft files went with it. 

If you are wondering, I am posting on a tablet which I received for Christmas.

 

7 minutes ago, RandomGuy1824 said:

Once we are in space can we get out and push to stabilize the orbit? And also is rcs counted as an engine?

RCS can be used to rotate the craft in space but not to push the craft. A kerbal can be used to push only for small orbit changes, but not on prograde because that would ruin the point of the challenge.

[theend3r]

12 minutes ago, RavenpawKSP said:

Sorry, the video keeps popping up when I quote, and can't be deleted.

And I lost my computer when my mother died a few months ago. All my current saves and craft files went with it. 

If you are wondering, I am posting on a tablet which I received for Christmas.

 

RCS can be used to rotate the craft in space but not to push the craft. A kerbal can be used to push only for small orbit changes, but not on prograde because that would ruin the point of the challenge.

Then it is simply physically impossible. Your videos mean nothing, I can post a video of landing at Jool or even the Sun but that doesn't mean anything. You either mod or use the debug menu.

[Tex_NL]

29 minutes ago, RavenpawKSP said:

The highest speed achieved was 41,232 m\s

This is simply NOT possible in any way. It is MORE than ten times Kerbins escape velocity and close to half that of the sun. In a stock atmosphere this absolutely impossible no matter what engines you're using.
Desperately repeating you did it over and over does not chance the fact that what you're saying IS NOT POSSIBLE !!!

Please take it from us 'old guys'. We clearly have a lot more experience in KSP.

P.S.
Why do I get the feeling I am feeding a troll?

[bigcalm]

Ok, to simply explain why we a) don't believe you and b) think this challenge is impossible

By going faster and faster in the atmosphere, you can raise your apoapsis so that it's outside the atmosphere.  However, crucially, you can only burn below 25k altitude with air-breathing only engines - and this is your periapsis.  Without oxidiser, it doesn't matter how fast you go whilst you're in atmosphere, your periapsis is still 25k or below.  This is not orbit.  Orbit is where your periapis and apoapsis are both at least 70k.

There's some tricky ways around it to be sure, but we don't believe that you've used them.  The tricky ways are:

* Use RCS as an engine when you reach apoapsis.  This kind of breaks the rules you've set (only air breathing engines).  RCS is just another form of engine, and it's not airbreathing.

* Get a gravity assist off the Mun to change your periapsis.  This would entail you going at least 3000 ms in the atmosphere below 25k and to time the burn fairly precisely.  Whilst this is possible, it would take an extremely carefully designed plane that was very aerodynamic, and I'm fairly sure if you had atmospheric heating turned on, your plane would explode due to overheating way before you got your apoapsis up to the height of the Mun.

* Escape Kerbin completely - this would mean going even faster than the previous one though you wouldn't have to time it precisely.  You said orbit - is solar orbit ok?

* Get out and push.  By using a Kerbonaut's RCS, you can change the periapsis by positioning them behind the vessel and moving forwards, occasionally diving back in to the vessel to pick up more propellant as needed.  Again, this breaks your rules on not using air-breathing engines.

I'd like to see the gravity assist attempted - it might be just about possible, but doubt that's what you've done.

[theend3r]

Just now, Tex_NL said:

This is simply NOT possible in any way. It is MORE than ten times Kerbins escape velocity and close to half that of the sun. In a stock atmosphere this absolutely impossible no matter what engines you're using.
Desperately repeating you did it over and over does not chance the fact that what you're saying IS NOT POSSIBLE !!!

Please take it from us 'old guys'. We clearly have a lot more experience in KSP.

P.S.
Why do I get the feeling I am feeding a troll?

Frankly, getting that speed is possible in stock, I should know, I achieved multiples of light speed when crashing on Kebin.

But orbiting is not possible.

[Tex_NL]

Just now, theend3r said:

Frankly, getting that speed is possible in stock, I should know, I achieved multiples of light speed when crashing on Kebin.

But orbiting is not possible.

OK, OK. You're right about that. There are indeed a few rare situations that can trigger a bug that explosively ejects you from the plains of reality.

[theend3r]

1 hour ago, bigcalm said:

I'd like to see the gravity assist attempted - it might be just about possible, but doubt that's what you've done.

I don't think gravity assist is possible but a "catcher" approch may work. Build your spaceplane to withstand impact from the back and place a heavy "catcher" in the orbit (preferably and E class asteroid) with a net of sorts that would catch the spaceplane catapulted into its orbit. Of course this would require incredible luck and mechanization (using kOS seems like a good idea here).

I'd love to see that and I believe its possible but I won't hold my breath.

Edit: I'm also pretty sure it can be done using rotation + separation of stages to produce a catapult. No one said it has to be SSTO.

Edited January 15, 2017 by theend3r

[Vanamonde]

A couple of posts have been trimmed from this thread. There's no need to be abusive and accusatory about a game. 

[theend3r]

I just tested this:

two decouplers (TR-XL -> TR-18A -> smallest probe) give you 100 m/s dV. Add it to the rotation catapult method and I'm sure this can be done. I just don't have the skills to get the apoapsis to 80+ with just jets but if you manage that, build a reaction wheel space catapult and combine it with this then you might make it.

Edited January 15, 2017 by theend3r