My first SSTO

[Aerospike]

20 hours ago, Majorjim! said:

Not bad for a first attempt dude. It's ugly as hell though, but most first SSTOs are!

Well different people have different tastes. It might not be the most efficient one, but I actually like its looks!

[AeroGav]

19 minutes ago, Azimech said:

My second SSTO. This one has a small cargo bay and can land on Minmus and back at KSC. Same procedure as the other one except I need to press one key extra: switch from Rapiers to nuke.

After parking I had 82 units of fuel left. Haven't tried with cargo yet. And I need a lot of radiator panels with this cockpit.

That first plane was so nice looking !

From a performance standpoint, you want to change to an inline cockpit, they resist heat so much better, but i must admit the pointy one looks good.

To go minmus / duna on a 30 tonner,  you want a 3 engine mix of rapier and nuke.

the mark 2 fuselage is very draggy so you need to start adding incidence to your wings to get good efficiency out of one.

I see you went with 2 rapier and 1 nuke.  I did too when i started, but i found myself always sweating on the oxidizer running out - unless i was very close to orbit,  the single nuke wouldn't keep me up there.   If you level off for the speedrun and have a design with decent lift/drag ratio,  you can get up to mach 5 air breathing on one rapier.     This means you can have two nukes which will carry you from mach 5 to orbit all by themselves, and unlike oxidizer engines you don't have to sweat on the fuel gauge cause it hardly moves.
 

ps. reaction wheels > rcs for space planes.  Drag matters more than weight.  If you really must have translation ability stick thrusters on the outside of a cargo bay, they will be shielded when bay doors are closed so no drag.

ps2.  for your minmus plane try using big S wings and strakes instead of modular wings, you want the fuel capacity.  if you are going with a 2 nuke no oxidizer design,  you need lots of wing area so it flies efficient in the upper atmosphere.   Replace liquid fuel fuselages with big s wings and strakes wherever possible.

9 minute nuclear ssto build (with flight footage) at 2x speed 

 

 

https://www.youtube.com/watch?v=XXhIb5OlSRY&t=595s

 

A mark 2 spaceplane with 2 nukes and 1 rapier - has a clamp o tron, rcs, cargo bay and seats 6 kerbals, can reach Duna.  Loading the oxidizer tanks is optional :-)https://kerbalx.com/AeroGav/ASES-SP2-Xkos-Dual-Nukes

Spoiler

As you can see, it has zero fuselage tanks, apart from the mk2 to size 1 adapters that are kind of forced on you.  All the LF is in wings, strakes, intakes and nose cones.

 

[Azimech]

Wow guys that's a lot to reply to, I still have to reply to Rune.

One quick thing: I didn't use oxidizer on the second: directly switched from rapiers to nuke at 30km, while AP is at 40. Again without touching the controls the plane raises it's AP to 70, the plane having a TWR of 0.4 it does so without problems, works every time.

 

 

[Azimech]

18 hours ago, Rune said:

Yeah, that's a plane with a lot of control authority and not enough rigidity in the longitudinal axis, then SAS can be a handful because your controls can invert/overcorrect when the torque on the plane is big enough. In those cases, lowering your control input will usually help. Another thing that helps is a CoL very close to the CoM, so the control torque can be kept to a minimum (you also save on drag quite a bit). Of course, for that you need a CoM that either stays in place or moves forward, but with the new fuel flow rules that is easy to do.

Actually I've noticed the SAS is being a lot worse than it was in 1.1.3. Proof: my turboprops and helicopters could fly in a straight line. Now the engine vibrations knock it off and I had to add trim tabs to counteract the new behaviour. So regardless of control authority, everything is fine until you touch the controls, be it SSTO or turboprop.

Quote

As to the SSTO, nice-looking first try. Now go about finding the limits! Payload fraction, dV on orbit, lowest drag... that kind of stuff. Oh, and a couple of tips:Tip#1: shock cones have the least drag per intake area, and a single of those can feed two RAPIERs. Less intake area=less drag. Drag is king in SSTOs.

I never calculate anything in KSP so that could take some time. As for the shock cones: I'd rather have two smaller intakes then, the nose remains what it is.

 

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Tip#2: With enough streamlining, 0.4~0.5 TWR designs can perfectly well go supersonic at sea level in less than a minute and basically run a straight line to orbit form there. And of course, low TWR=low engine mass=more mass for other stuff.

 

That's why my initial angle is so important. And don't forget, I'm lazy. I don't want to pilot the plane, I've been playing flight sims since 1983. Now I just want to push a few buttons and wait until it's in orbit. And that's exactly what these two planes do: go supersonic within a minute and fly a straight line into orbit.

Quote

Rune. It's an entertaining rabbit hole you got yourself into.

That's right

 

[Azimech]

This video throws everything we think we know about air intakes out the window.

 

[Rune]

9 minutes ago, Azimech said:

This video throws everything we think we know about air intakes out the window.

Hum. A shorter-duration, high-G launch would have been a better test (at slow accelerations, the differences in weight should get magnified, especially at low speeds), but it is an interesting one. I still pick my intakes mostly on account of looks, the main thing with them is having just enough of them.

 

Rune. Drag/intake area is the relevant figure here, not just drag... except for nosecones.

[AeroGav]

8 minutes ago, Azimech said:

This video throws everything we think we know about air intakes out the window.

 

It's not just about drag though.   Intakes have a velocity profile, as they get faster they take in more air, then reach their peak and start taking less air as speed rises.   Engines also have a thrust velocity curve where they produce more power as you get faster, then hit their peak and start going off the boil.

As the thrust rises so does air consumption.   If you are using a RAPIER, which peaks at mach 3.75 and delivers a useful amount of power out to mach 5, you need an intake with a similarly good top end.       I've found the shock cone, adjustable ramp intake and pre-cooler are all capable of keeping a RAPIER happy on a one engine per intake basis.    

After watching this video, i tried using diverterless supersonic fuselage intake, but the problem is they start to fade badly after mach 3 , and my engines started spluttering past mach 4.  I ran two intakes per engine , got maybe 100m/s faster then same thing.   Similar effect with those radial mount supersonic intakes.  Work fine below mach 3 then no matter how much you spam you get spluttering at high alt.

@Azimech I'm trying to make a nuke version of your first SSTO while retaining as much of the look as i can, so i'm staying with dual ramp intakes.

[Azimech]

20 minutes ago, Rune said:

Hum. A shorter-duration, high-G launch would have been a better test (at slow accelerations, the differences in weight should get magnified, especially at low speeds), but it is an interesting one. I still pick my intakes mostly on account of looks, the main thing with them is having just enough of them.

 

Rune. Drag/intake area is the relevant figure here, not just drag... except for nosecones.

I just made a screenshot of you having a rep of 4000. Reminds me of a certain Amiga. Anyway ... you're one of those rare persons with more rep than posts.

The difference between all of them isn't gigantic ... but if you have a lot of those on your plane ...

[Azimech]

29 minutes ago, AeroGav said:

It's not just about drag though.   Intakes have a velocity profile, as they get faster they take in more air, then reach their peak and start taking less air as speed rises.   Engines also have a thrust velocity curve where they produce more power as you get faster, then hit their peak and start going off the boil.

As the thrust rises so does air consumption.   If you are using a RAPIER, which peaks at mach 3.75 and delivers a useful amount of power out to mach 5, you need an intake with a similarly good top end.       I've found the shock cone, adjustable ramp intake and pre-cooler are all capable of keeping a RAPIER happy on a one engine per intake basis.    

After watching this video, i tried using diverterless supersonic fuselage intake, but the problem is they start to fade badly after mach 3 , and my engines started spluttering past mach 4.  I ran two intakes per engine , got maybe 100m/s faster then same thing.   Similar effect with those radial mount supersonic intakes.  Work fine below mach 3 then no matter how much you spam you get spluttering at high alt.

@Azimech I'm trying to make a nuke version of your first SSTO while retaining as much of the look as i can, so i'm staying with dual ramp intakes.

Aha okay :-) Don't worry, the F15 type intakes don't need to stay. I will go for the sub-hypersonic intakes in the future. And I like the effort :-)

 

[Matuchkin]

On 30/11/2016 at 6:01 AM, Azimech said:

 

You? Never built an SSTO before this one?

Well it's about time, I guess...

3 hours ago, Aerospike said:

Well different people have different tastes. It might not be the most efficient one, but I actually like its looks!

Naww, I'd like something streamlined, that starts from the cockpit, flows and blends together with the wings, passes some ingrained intakes, then ends with a smooth tail. That's the kind of SSTO, like skylon. Of course, only Rune can probably do that.

[Triop]

3 hours ago, Azimech said:

This video throws everything we think we know about air intakes out the window.

 

Nice test, good info, have to try this myself.

Groetjes uit Brabant 

[Azimech]

2 hours ago, Matuchkin said:

You? Never built an SSTO before this one?

Well it's about time, I guess...

 

Maybe, just maybe I've built something like that using a lot of mods during the age of Errordynamics^TM so if that's the case, it doesn't count ;-)

50 minutes ago, Triop said:

Nice test, good info, have to try this myself.

Groetjes uit Brabant 

Niet mijn filmpje, inderdaad goeie test, groeten uit Zuid-Holland - binnenkort Utrecht ;-)

[Majorjim!]

Just now, Azimech said:

Maybe, just maybe I've built something like that using a lot of mods during the age of Errordynamics^TM so if that's the case, it doesn't count ;-)

LOL, you totally have made one before. Pants on fire! Just like the first SSTO I posted here was my 'first'.

[Azimech]

Just now, Majorjim! said:

LOL, you totally have made one before. Pants on fire! Just like the first SSTO I posted here was my 'first'.

I'd rather totally forget everything about anything pre -0.23

[AeroGav]

4 hours ago, Azimech said:

Aha okay :-) Don't worry, the F15 type intakes don't need to stay. I will go for the sub-hypersonic intakes in the future. And I like the effort :-)

 

That's what i came up with : - 

• Single RAPIER at the back
• replaced the tail connectors with a pair of nukes
•  added an inline clamp o tron
•  some canards sorry.  that's a fairly big visual change
• some vertical big s strakes as tails

The wings are angled so it flies on prograde assist, though it does Phugoid a bit if left unsupervised (look that up on wikipedia).  You can suppress the worst of the phugoids by locking nose angle with stability assist when it starts doing something that's obviously not a good idea.   You can even - shock - fly manually if you want to.

It goes supersonic about 8 or 9km, then reached 1350 at 20km and was still picking up speed at a good rate when ....

BOOM !  

Cockpit exploded from overheating.  This took me by surprise as my mk1 nuclear SSTO i made a video of, reaches 1600 on jet power alone and merely glows red for a few seconds.    My mk1 inline cockpit however has an engine precooler in front, then an NCS adapter, then a fly by wire hub nose thing, so it's some distance back.  Maybe having a rapier directly behind also helps, engine nozzles are good at radiating heat.

So, second attempt, I press Space Bar to start the nukes as soon as we pass 1300 m/s, left it on prograde,  and we zoom upstairs.  At 45km we're doing 2400 m/s and climbing fast, still got 40% fuel left.   At this altitude i'd consider us to be above the worst heating, and on all my other designs i keep the throttle open to maximise our oberth effect since we're headed to minmus.

BOOM !  

 

Well I'm not sure what to do now.   I could change to an inline mk2 cockpit, put a mk2 to mk1 adapter on the front then a nose cone.  That would change the appearance too much i think, and have it looking more like everything else i build.

Or I could add more wings so it climbs quicker and gets less hot - same thing re: appearance.

Or just be really careful flying the airplane.   I should have paused my burn as soon as our AP went over 70km, circularized to low orbit then made a shot on Minmus from there, and we'd have made it.   I'm just trying to decide if the project is still worth continuing, 

 

[Azimech]

Number three. A little bit tedious to get to orbit (gonna lower initial angle with a few degrees) but the same formula, not touching the stick. This is the amount of fuel I have left after reaching orbit. Strangely enough, VOID doesn't show TWR and Dv this session ... it's a beta, maybe next release will be better.

 

 

.

 

 

30 minutes ago, AeroGav said:

That's what i came up with : - 

• Single RAPIER at the back
• replaced the tail connectors with a pair of nukes
•  added an inline clamp o tron
•  some canards sorry.  that's a fairly big visual change
• some vertical big s strakes as tails

The wings are angled so it flies on prograde assist, though it does Phugoid a bit if left unsupervised (look that up on wikipedia).  You can suppress the worst of the phugoids by locking nose angle with stability assist when it starts doing something that's obviously not a good idea.   You can even - shock - fly manually if you want to.

It goes supersonic about 8 or 9km, then reached 1350 at 20km and was still picking up speed at a good rate when ....

BOOM !  

Cockpit exploded from overheating.  This took me by surprise as my mk1 nuclear SSTO i made a video of, reaches 1600 on jet power alone and merely glows red for a few seconds.    My mk1 inline cockpit however has an engine precooler in front, then an NCS adapter, then a fly by wire hub nose thing, so it's some distance back.  Maybe having a rapier directly behind also helps, engine nozzles are good at radiating heat.

So, second attempt, I press Space Bar to start the nukes as soon as we pass 1300 m/s, left it on prograde,  and we zoom upstairs.  At 45km we're doing 2400 m/s and climbing fast, still got 40% fuel left.   At this altitude i'd consider us to be above the worst heating, and on all my other designs i keep the throttle open to maximise our oberth effect since we're headed to minmus.

BOOM !  

 

Well I'm not sure what to do now.   I could change to an inline mk2 cockpit, put a mk2 to mk1 adapter on the front then a nose cone.  That would change the appearance too much i think, and have it looking more like everything else i build.

Or I could add more wings so it climbs quicker and gets less hot - same thing re: appearance.

Or just be really careful flying the airplane.   I should have paused my burn as soon as our AP went over 70km, circularized to low orbit then made a shot on Minmus from there, and we'd have made it.   I'm just trying to decide if the project is still worth continuing, 

 

I solved it by adding radiators. Yes they consume electricity and really start to work when in space but it helps just enough.

Edited December 2, 2016 by Azimech

[fourfa]

Magic Antenna (C-16) on the nose of that Mk2 cockpit will solve the heating issue.  Linear RCS thruster works too.

[Rune]

13 hours ago, AeroGav said:

It's not just about drag though.   Intakes have a velocity profile, as they get faster they take in more air, then reach their peak and start taking less air as speed rises.   Engines also have a thrust velocity curve where they produce more power as you get faster, then hit their peak and start going off the boil.

As the thrust rises so does air consumption.   If you are using a RAPIER, which peaks at mach 3.75 and delivers a useful amount of power out to mach 5, you need an intake with a similarly good top end.       I've found the shock cone, adjustable ramp intake and pre-cooler are all capable of keeping a RAPIER happy on a one engine per intake basis.    

After watching this video, i tried using diverterless supersonic fuselage intake, but the problem is they start to fade badly after mach 3 , and my engines started spluttering past mach 4.  I ran two intakes per engine , got maybe 100m/s faster then same thing.   Similar effect with those radial mount supersonic intakes.  Work fine below mach 3 then no matter how much you spam you get spluttering at high alt.

@Azimech I'm trying to make a nuke version of your first SSTO while retaining as much of the look as i can, so i'm staying with dual ramp intakes.

That is all very true and all, but let me just add that you can actually use one shock cone per two RAPIERs. About 0.5 "units of area" (whatever they are) per RAPIER, or less, in the high-speed intakes, is what is required for RAPIERs to really shine. Precoolers have 0.5, but hey, you don't have to increase the total frontal area to use them, so they should be the sleekest thing if you can use them.

13 hours ago, Azimech said:

I just made a screenshot of you having a rep of 4000. Reminds me of a certain Amiga. Anyway ... you're one of those rare persons with more rep than posts.

The difference between all of them isn't gigantic ... but if you have a lot of those on your plane ...

Wow, I totally didn't notice the milestone! In any case, I think that is mostly a function of me posting mostly either stuff for people to DL (which they seem to like), or giving someone advice (less rep/post ratio, but much more satisfying in the end, and if you are nice enough doing it you make lots of forum friends).

 

Rune. Also, my main thing have always been SSTOs, and those are very popular.

[NSEP]

Im not the only one who does something impressive at first try! Pfew!

My first SSTO was a rocket SSTO that is also a VTOL rocket.

Edited December 2, 2016 by NSEP

[OrbitalBuzzsaw]

12 hours ago, Azimech said:

Number three. A little bit tedious to get to orbit (gonna lower initial angle with a few degrees) but the same formula, not touching the stick. This is the amount of fuel I have left after reaching orbit. Strangely enough, VOID doesn't show TWR and Dv this session ... it's a beta, maybe next release will be better.

 

 

.

 

 

I solved it by adding radiators. Yes they consume electricity and really start to work when in space but it helps just enough.

Y u no KER?

[Azimech]

1 hour ago, OrbitalBuzzsaw said:

Y u no KER?

Not yet ... I should download it.

[AeroGav]

14 hours ago, Azimech said:

I solved it by adding radiators. Yes they consume electricity and really start to work when in space but it helps just enough.

Ok well i put it on KerbalX "as is".  Radiators don't really work in an atmosphere.   I am already using the antenna trick, unfortunately the cockpit gets hot before the antenna does.  Just have to be careful on ascent.  Because of these problems it's not up to the standard of something i'd normally put on KerbalX these days.  

I am beginning to think the pointy cockpit, if it has a use, is for non-nuclear LKO shuttles only, or maybe Whiplash powered designs.  Stuff that doesn't get too fast airbreathing (whiplash) or which climbs through the upper atmosphere very fast on purely chemical propulsion.  BTW the inline version is more crashworthy too, though this thing's still fairly safe on impact due to low landing speeds.

https://kerbalx.com/AeroGav/77I--Minmus-mod

 

 

For a really foolproof nuke ship, try the XKOS https://kerbalx.com/AeroGav/ASES-SP2-Xkos-Dual-Nukes

For something ridiculously capable, try the Wyvern https://kerbalx.com/AeroGav/Wyvern-Offroad - you'll like it Azimech it's a tail dragger !

Interestingly, both of the above ships were other folk's problem designs that I fixed, they ended up better than any of my "clean sheet" efforts to date.