Is a Orbiting Spiral/Mig-105 possible?

[Jestersage]

While there's a bunch of X-20 and Lunex attempts (no craft files over at KerbalX though), I am surprise not many people were doing SpiralOS-type launches: http://www.buran.ru/htm/molniya3.htm

So I decide to make one myself. First using a modified Ravenspear Mk3 with 4 ramjet, then gone bigger with Mk3 parts that employed a similar layout (5 ramjet in total). The booster rocket is a Thumper with structural wings attached on the side. the MiG itself is a small Mk-2 body with 1 long rocket fuselage and a RAPIER engine at the back.

Launch plan: Fly to 20k at fast as possible; On the modified Ravenspear I got to >1000 m/s, while Mk3 based carrier I got ~800m/s. Then the SpiralOS detached, the booster will kick in, and I pitch up to 45 degree or as high as I can. Once the booster is depleted, the MiG would detach and fly on the RAPIER.

No dice -- the SpiralOS goes suborbital but that's about that... Ironically I have a better luck with a X-20 on top of a Titan-IIIc analogue. No idea if I should switch to a liquid booster (powered by vector) or even use a 2.5m liquid booster (with Vector too).

Not sure what i did wrong. Anyone can help?

[Majorjim!]

craft file?

[Jestersage]

How do I upload one? KerbalX or Dropbox?

[Alchemist]

Sounds like you don't have the Delta v required. Note that the original design incorporates 2-stage liquid rocket (H2/O2, they also considered using H2/F2) plus the spaceplane's own propulsion (although it's just for minor corrections and deorbiting).

[KerikBalm]

If they're looking at using fluorine... you know they were having problems. You've got to be desperate to use fluorine as a fuel

If H2-Lox isn't cutting it, give up. The complication of using Fluorine will kill it anyway, despire the better Isp

[Corona688]

Not enough delta-V?  Not enough fuel.  You can tell from how much fuel the stock Aeris carries, about what it takes to reach space in a spaceplane that size.

[Jestersage]

18 hours ago, Corona688 said:

Not enough delta-V?  Not enough fuel.  You can tell from how much fuel the stock Aeris carries, about what it takes to reach space in a spaceplane that size.

Except stock Aeris-4 is a SSTO, while mine is not -- it's a three stage model.

And before I craft this I modified a Stratolauncher so it can head to 20k and launch a similar craft (technically bigger with crew cabin), and that one orbits just fly.

The reason I am designing it as such right now is hopefully able to launch the booster+spacecraft at +1k m/s.

[Guest]

23 hours ago, KerikBalm said:

If they're looking at using fluorine... you know they were having problems. You've got to be desperate to use fluorine as a fuel

If H2-Lox isn't cutting it, give up. The complication of using Fluorine will kill it anyway, despire the better Isp

Complication using fluorine?

Pfft, all that happens is that fluorine happens to be the most reactive element, and that the rocket exhaust will make it rain hydrofluoric acid!

[Corona688]

On 7/4/2016 at 10:02 AM, Jestersage said:

Except stock Aeris-4 is a SSTO, while mine is not -- it's a three stage model.

No reason you can't, then.  I've added more capacity to the Aeris with a drop-tank, maybe you can do that to yours?

[Jestersage]

1 hour ago, Corona688 said:

No reason you can't, then.  I've added more capacity to the Aeris with a drop-tank, maybe you can do that to yours?

Did you fly it at +1000 m/s where it's red hot? That was my attempt. Pretty much accelerate it to close 1000 m/s before launching it.

If I am suppose to do it at around 300m/s, my modified Stratolauncher does just fine.

[Snark]

Moving to Gameplay Questions.

[Corona688]

17 hours ago, Jestersage said:

Did you fly it at +1000 m/s where it's red hot? That was my attempt. Pretty much accelerate it to close 1000 m/s before launching it.

If I am suppose to do it at around 300m/s, my modified Stratolauncher does just fine.

Since you're flying it multi-stage anyway, why not make it go straight up?

[Jestersage]

2 hours ago, Corona688 said:

Since you're flying it multi-stage anyway, why not make it go straight up?

1. Already done that with a Dyna-Soar test type. (In fact testing a Lunex right now)
2. Hopefully increase recovery by allowing the plane to keep flying while I make the Craft orbit
3. Challenge!

[Corona688]

Well, if it can't reach orbit, the usual culprits are

a) not enough lift -- you waste more fuel keeping the same altitude until you're ready to make your break-free burn.

b) not enough fuel.

Since you're already dropping tanks, I suspect the former, particularly given the 'lifting body' shape of the mig-105.  You'll get a lot less lift from that shape in KSP than you would in the real world, it'd be pretty much just a sideways rocket.

Edited July 6, 2016 by Corona688

[Jestersage]

So this is actually my ship:
Front view
Rear view

And I did remove majority of fuel from the carrier plane, so it can actually reach 20,000m alt at 700 m/s

When I tested a similar orbiting craft by modifying the stock Stratolauncher, it launches fine. The only differences is that

1. Use the original Hammer SRB
2. Did not launch it at 700 m/s or higher speed (I basically keep flying until the red drag streaks appear)
3. Use the RAPIER. Probably a bad idea to begin with.

Could those two differences made it difficult to make the craft form an actual orbit? (it reaches 80k no problem... just doesn't form an orbit)

Edited July 7, 2016 by Jestersage

[Corona688]

I think the detachable craft might as well fly purely ballistically.

[Jestersage]

55 minutes ago, Corona688 said:

I think the detachable craft might as well fly purely ballistically.

Not enough Wings? But I tested it with Stratolauncher and it was fine?!

[Corona688]

Just now, Jestersage said:

Not enough Wings? But I tested it with Stratolauncher and it was fine?!

I had an unclear picture of your craft in my head.  I thought it might be one big craft with drop tanks, not a little one atop a big one.  If the Stratolauncher works, use the Stratolauncher.

But the point of a Stratolauncher sky sled thing is leaving all your jet parts behind.  Above 20,000, they're only barely functioning anyway.

[Jestersage]

28 minutes ago, Corona688 said:

I had an unclear picture of your craft in my head.  I thought it might be one big craft with drop tanks, not a little one atop a big one.  If the Stratolauncher works, use the Stratolauncher.

But the point of a Stratolauncher sky sled thing is leaving all your jet parts behind.  Above 20,000, they're only barely functioning anyway.

Yeah. The oribital craft is the tiny Mk-II plane at the top with the booster at the back, not the big ass sonic capable carrier plane.

I only kept the Rapier because the original Mig-105 called for a Jet for landing correction, otherwise I would have just go with Aerospike.

[Corona688]

You don't need a Rapier for landing correction, a Juno will do.  Less weight makes you faster on the way up and slower on the way down.

Edited July 7, 2016 by Corona688

[Jestersage]

20 hours ago, Corona688 said:

You don't need a Rapier for landing correction, a Juno will do.  Less weight makes you faster on the way up and slower on the way down.

The reason that I used Rapier is that The Mig-105 would have contained both a Rocket Engine and a Jet engine:

From the http://www.buran.ru/htm/molniya3.htm

Quote

   The power plant included:
     - a liquid propellant engine (LPE) for orbital propulsion, with the 1,500 kg/f of thrust (specific pulse of 320 sec, fuel consumption of 4.7 kg/sec). It was employed to change orbital inclination and produce a braking pulse to dive off the orbit. Later versions would feature a more powerful LPE with thrust in vacuum of 5,000 kg/f, boasting a variable thrust capability, adjusting it slightly to 1,500 kg/f to allow orbital manoeuvres;
     - two emergency situation braking 16 kg/f LPEs, fed from main LPE fuel system by the compressed helium displacer;
     - an LPE attitude control unit of six 16 kg/f engines for coarse adjustment and ten 1 kg/f engines for fine manoeuvres;
     - a turbojet kerosene 2,000 kg/f engine with specific fuel consumption of 1.38 kg/kg*h to allow subsonic propulsion and landing. It had an adjustable ram air intake at the bottom of the fin, opened only before starting the turbojet.

The entire Spiral mission profile, from what I understand, is this:

1. Carrier plane, carrying the Mig-105 on top of it, would fly horizontally to hypersonic speed to upper atmosphere. (The main attraction to replicate it in KSP is the hypersonic aspect -- the Stratolauncher, even with the Whiplash, only goes supersonic. Obviously in stock KSP, hypersonic just mean +1000m/s)
2. Mig-105 detach and fire its two stage booster. (Here is my question: should I use a liquid rocket instead of that Solid Booster?)
3. After the booster detach, the Mig-105 maintain orbit and orbit altitude using its own propulsion.
4. After deorbiting, Mig-105 would use the jet engine for landing.

Soviets, for all their fault, designed some pretty advance spacecrafts.

Edited July 8, 2016 by Jestersage

[Corona688]

I suspect it was actually intended to use Sukhoi T-4 supersonic bomber -- its payload capacity and the Spiral's fully-fueled weight are identical.  But the T-4 was cancelled before the Spiral was, making it a cockpit in search of an aircraft.

That'd lower the requirements of your sled craft a bit.

27 minutes ago, Jestersage said:

1. Mig-105 detach and fire its two stage booster. (Here is my question: should I use a liquid rocket instead of that Solid Booster?)

Rule of thumb is, don't use solids in anything but your bottom stage.  They're super heavy and actually more efficient on the ground than the high atmosphere.

Edited July 8, 2016 by Corona688

[Jestersage]

1 hour ago, Corona688 said:

I suspect it was actually intended to use Sukhoi T-4 supersonic bomber -- its payload capacity and the Spiral's fully-fueled weight are identical.  But the T-4 was cancelled before the Spiral was, making it a cockpit in search of an aircraft.

That'd lower the requirements of your sled craft a bit.

Rule of thumb is, don't use solids in anything but your bottom stage.  They're super heavy and actually more efficient on the ground than the high atmosphere.

1) So it's probably closer to Ravenspear Mk-III?
2) Thanks for the booster's idea. Will be testing out using liquid rocket instead.
3) Should I just use RAPIER, or Aerospike+Juno Jet?

Edited July 8, 2016 by Jestersage

[Corona688]

1) Yes, just turbojets.

I haven't been able to make the RAPIER work for me tbh, my spaceplanes have all been turbojets + various rocket engines.  The aerospike, annoyingly, has no thrust vectoring, which is really annoying in the upper atmosphere where it's still thick enough to send you spinning but too thin for your control surfaces to use.  My favorite for small craft is the swivel, ymmv.

Edited July 8, 2016 by Corona688

[Jestersage]

Okay, last report on this thread:

I had gone with a Vector-based LRB such that it outputs 670N thrust; even though it burns shorter, it seems to be more than enough to take it to outer Kerbin atmosphere. However, I still can't just rely on the booster to complete the orbit. So I swapped it from Rapier to Dart + Juno, which allows me to orbit and deorbit. The tiny Juno is more than enough for course correction.

I had tried two carriers: One is the same Mk-3 based version, which requires me to reduce fuel further to decrease mass. The other, using a lengthened Ravenspear Mk-III with more jets, allowed me to launch it perfectly.

TBH, which carrier would be closer to the Spiral 50/50 carrier planet, Mk-II or Mk-III? The one on Kerbal X is Mk-III, but it can't even go supersonic!

Edited July 11, 2016 by Jestersage