My first SSTO in stock KSP

[Karol van Kermin]

Hey there!

I was playing a lot of KSP RO recently and I wanted to be one of the first guys to ever build a SSTO in RO. But I have never built a SSTO before, neither in regular KSP. So I decided to build one, just to check if there are any unknown issues. So, here it is! The Arrowspike A-1. Let me know what you think about it!

It is using 2x R.A.P.I.E.R. Engines to get it into Low Kerbin Orbit and it can carry up to 4x Kerbals and plenty snacks. The only known issue I had is that I appeared to have ran out of electric charge just before landing (it crashed on KSC :/ ). Also I decided to use a crew cabin instead of a cockpit, to avoid aerodynamic resistance. Here are some pictures of it:

 

 

 

 

 

 

Thank you very much for taking your time looking at my amazing creation !

 

 

 

Edited October 30, 2016 by Karol van Kermin
grammar

[OrbitalBuzzsaw]

Nice, although RSS SSTO's are not that uncommon, such as @UnusualAttitude's Carderie spaceplanes, and a few others I can't remember off the top of my head.

[UnusualAttitude]

That's a neat little SSTO there @Karol van Kermin, congratulations! Although with the TWR that thing must have, it really doesn't need wings... 

SSTO rockets are quite possible in RSS, but with a correspondingly awful payload fraction, and they will be difficult to recover and reuse.

If you're looking for inspiration for SSTO spaceplanes, Carderie can be seen in action here.

A forum user called @MoNsTroo built a much more convincing Skylon replica which can be seen here.

Be aware that both MoNsTroo and I had to create custom engine .cfg files (based on the REL SABRE engine) to make this happen. I don't believe it is possible to get a spaceplane with a useful payload to orbit with stock engines such as RAPIERs in RSS. But it would be great if someone could prove me wrong...

Even with magical made-up engines, there a still quite a few challenges. The lack of any suitable landing gear for such a beast in recent versions of KSP, for example.

Edited October 30, 2016 by UnusualAttitude

[Karol van Kermin]

 

8 hours ago, UnusualAttitude said:

That's a neat little SSTO there @Karol van Kermin, congratulations! Although with the TWR that thing must have, it really doesn't need wings... 

SSTO rockets are quite possible in RSS, but with a correspondingly awful payload fraction, and they will be difficult to recover and reuse.

If you're looking for inspiration for SSTO spaceplanes, Carderie can be seen in action here.

A forum user called @MoNsTroo built a much more convincing Skylon replica which can be seen here.

Be aware that both MoNsTroo and I had to create custom engine .cfg files (based on the REL SABRE engine) to make this happen. I don't believe it is possible to get a spaceplane with a useful payload to orbit with stock engines such as RAPIERs in RSS. But it would be great if someone could prove me wrong...

Even with magical made-up engines, there a still quite a few challenges. The lack of any suitable landing gear for such a beast in recent versions of KSP, for example.

well, I wanna correct myself by saying that im playing in ro, not rss only. I managed to build an ssto in ro before but I had difficulties in reentry.

But Im astonished! These ssto's you've shown me are honestly amazing. I also have a couple of questions for you:

Which mods are you using for the cargo bay?

How have you done the shielding?

Why is the irl Skylon still not in use?!

 

Thank you very much for showing me these amazing creations!

 

Edited October 31, 2016 by Karol van Kermin

[UnusualAttitude]

Thank you, but again, the only merit I can claim is in the airframe design. I tweaked the engine to suit my needs.

3 hours ago, Karol van Kermin said:

Which mods are you using for the cargo bay?

The cargo bay is courtesy of Nertea's MKIV system mod.

3 hours ago, Karol van Kermin said:

How have you done the shielding?

There isn't any. Just like the proposed Skylon spaceplane, it survives thanks to a very low ballistic coefficient when empty of fuel during re-entry. I set my re-entry perigee to 70+ km over the desired landing site and keep the nose well up during the entire descent. Note that I designed this in KSP 1.0.4 and I could reliably get it down with 100% re-entry heat. Some parameter must have changed since then, and in my current install (1.1.2) re-entry is much more sketchy. You might have to resort to using the magical airbrakes.

3 hours ago, Karol van Kermin said:

Why is the irl Skylon still not in use?!

Because many people are still sceptical as to whether the engines that Reaction Engines Ltd are working on will achieve the stated performance, or that an airframe this light could actually be produced. I personally believe that such a machine could be built, given enough time and billions of $, (although it wouldn't necessarily meet the ambitious specs proposed by REL) but the problem is that in the present state of affairs, the launch market simply may not require such an expensive project for small payloads. Until there is a requirement or an incentive to be throwing thousands of tonnes to LEO, and full reusability becomes mandatory, at least.

PS: I give my opinion since the OP asked. Please don't turn his/her thread into a "Skylon sucks/Skylon is awesome" debate, guys.

Edited October 31, 2016 by UnusualAttitude

[Karol van Kermin]

8 hours ago, UnusualAttitude said:

There isn't any. Just like the proposed Skylon spaceplane, it survives thanks to a very low ballistic coefficient when empty of fuel during re-entry. I set my re-entry perigee to 70+ km over the desired landing site and keep the nose well up during the entire descent. Note that I designed this in KSP 1.0.4 and I could reliably get it down with 100% re-entry heat. Some parameter must have changed since then, and in my current install (1.1.2) re-entry is much more sketchy. 

Wikipedia just told me:

The relatively light vehicle would then re-enter the atmosphere and land on a runway, being protected from the conditions of re-entry by a ceramic compositeskin. When on the ground, it would undergo inspection and necessary maintenance. If the design goal is achieved, it should be ready to fly again within two days.

 

Edited October 31, 2016 by Karol van Kermin

[UnusualAttitude]

Indeed. But apparently this is nothing as heavy or as fragile as the ceramic tiles that protect the space shuttle. At least this is what REL - who claim to have done the maths - say.

One must therefore assume that the procedural tanks that make up Caderie's fuselage are considered by the game to be ceramic coated.  The critical part is the nose tank, FYI.

[Karol van Kermin]

2 minutes ago, UnusualAttitude said:

Indeed. But apparently this is nothing as heavy or as fragile as the ceramic tiles that protect the space shuttle. At least this is what REL - who claim to have done the maths - say.

One must therefore assume that the procedural tanks that make up Caderie's fuselage are considered by the game to be ceramic coated.  The critical part is the nose tank, FYI.

Do you have a clip of it reentering, if yes, then I would love to see it!

[UnusualAttitude]

I'm not equipped for video capture,  but if you like (and if I have time tomorrow) I could post a screenshot album of a full flight with flight data.

[Karol van Kermin]

1 minute ago, UnusualAttitude said:

I'm not equipped for video capture,  but if you like (and if I have time tomorrow) I could post a screenshot album of a full flight with flight data.

This would be great! Also, can you keep mechjeb turned on, so I can see whats going on there? Thank you very much!

[UnusualAttitude]

23 hours ago, Karol van Kermin said:

Also, can you keep mechjeb turned on, so I can see whats going on there?

We don't do Mechjeb. KER flight data and FAR data will have to do, but here you go.

Just to be clear, this is science fiction. There are a lot of fluffs and workarounds I had to resort to to get this flying (using methane rather than hydrogen, large wings to allow it to re-enter, doing away with AJE and intake air entirely because I kept getting negative thrust values, etc....) Feel free to send a PM if you have any questions. I don't want to clutter up your craft thread any more... 

[Karol van Kermin]

Amazing!

Edited November 1, 2016 by Karol van Kermin

[UnusualAttitude]

1 hour ago, Karol van Kermin said:

This is AMAZING!

This is SCIENCE fiction.... 

1 hour ago, Karol van Kermin said:

Why is there more oxidiser on board than lqd methane?

Because..

CH₄ + 2 O₂ → CO₂ + 2 H₂O 

...and the molecular mass of CH₄ is 16 whereas that of O₂ is 32. So you will need much more oxidiser (by mass) to burn that methane fuel, despite the fact that most rocket engines are run fuel-rich, and that Carderie does not require oxidiser for the open-cycle part of the ascent. That's why a true dual cycle engine would be such a big deal for rocket performance: you save a lot of mass because of the airbreathing phase. The difference is even greater for other fuels: the Space Shuttle external tank carried about 100 tonnes of liquid hydrogen, but well over 600 tonnes of liquid oxygen.

1 hour ago, Karol van Kermin said:

I would highly recommend using the mod adjustable landing gear!

So would I, but KSP 1.1 killed it. Unless there is a fork or a new version I missed?

Edited November 1, 2016 by UnusualAttitude

[Karol van Kermin]

4 minutes ago, UnusualAttitude said:

This is SCIENCE fiction.... 

Because..

CH₄ + 2 O₂ → CO₂ + 2 H₂O 

...and the molecular mass of CH₄ is 16 whereas that of O₂ is 32. So you will need much more oxidiser (by mass) to burn that methane fuel, despite the fact that most rocket engines are run fuel-rich, and that Carderie does not require oxidiser for the open-cycle part of the ascent. The difference is even greater for other fuels: the Space Shuttle external tank carried about 100 tonnes of liquid hydrogen, but well over 600 tonnes of liquid oxygen.

So would I, but KSP 1.1 killed it. Unless there is a fork or a new version I missed?

I forgot to read your last sentence lol xD! So I posted my questions here. If youre interested, some1 made a RSS SSTO (reuseable) challenge here . You could show off there.

Also, I actually dont really care about this thread so you can keep commenting on it .

Thank you very much for that explanation! Do you have chemistry at school?

Edited November 1, 2016 by Karol van Kermin

[UnusualAttitude]

8 minutes ago, Karol van Kermin said:

If youre interested, some1 made a RSS SSTO (reuseable) challenge here . You could show off there.

I had a look at that thread and there are some impressive designs, such as Winged's Single Stage to Martian Flyby rocket. 

But that thread is for people using real life engines simulated in KSP. This is why I only showcase Carderie when people ask. I made up the engine config myself, and the real SABRE hasn't flown yet...

11 minutes ago, Karol van Kermin said:

Do you have chemistry at school?

I've studied quite a lot of things at various points in my life... general physics, geology and environmental science, and aviation history.