Help with personal aircraft challenge career

[Jarin]

I've been trying to get some experience with aircraft, since I'd been making spaceplanes in my old 1.1.3 career, so I thought I'd try to challenge myself a bit. I even had vague thoughts about making it an actual Challenge, and posting this as the first entry.

Primary rule: No usage of VAB or launch pad, all craft must take off horizontally and preferably land the same way. Funding efficiency and reusability is a primary concern, and runway landing is always the goal, but no hard rule about full recovery.

I'll spare you the first couple rocket-sleds I built; those don't matter. But here's my first real aircraft.

The Spirit 1 was a great little workhorse, lasting me quite a while, and having several variants. Starting there, I pushed through the tech tree and was doing pretty decently for a while. Since we still can't insert imgur albums, here's the link to a quick career summary: http://imgur.com/a/ucdXy

And here's where I am now:

Spoiler

My problem is, I've hit a bit of a wall. The Panther is a fun engine, but it just doesn't have the upper-atmosphere power I need to start reaching beyond LKO. I've mined Kerbin of most of its science, and finishing that up (just the south pole and badlands left) won't get me enough to push to Hypersonic Flight. 

Where should I go from here? My design creativity is running out, after the monstrosity that is the This Might Work. I still need to pull 300 more science from somewhere to push for Hypersonic, and that's ignoring everything else (I mean, I still don't even have reaction wheels). Any advice, whether on research or aircraft design, would be greatly appreciated.

Edited October 28, 2016 by Jarin

[AeroGav]

58 minutes ago, Jarin said:

I've been trying to get some experience with aircraft, since I'd been making spaceplanes in my old 1.1.3 career, so I thought I'd try to challenge myself a bit. I even had vague thoughts about making it an actual Challenge, and posting this as the first entry.

Primary rule: No usage of VAB or launch pad, all craft must take off horizontally and preferably land the same way. Funding efficiency and reusability is a primary concern, and runway landing is always the goal, but no hard rule about full recovery.

I'll spare you the first couple rocket-sleds I built; those don't matter. But here's my first real aircraft.

The Spirit 1 was a great little workhorse, lasting me quite a while, and having several variants. Starting there, I pushed through the tech tree and was doing pretty decently for a while. Since we still can't insert imgur albums, here's the link to a quick career summary: http://imgur.com/a/ucdXy

And here's where I am now:

  Reveal hidden contents

My problem is, I've hit a bit of a wall. The Panther is a fun engine, but it just doesn't have the upper-atmosphere power I need to start reaching beyond LKO. I've mined Kerbin of most of its science, and finishing that up (just the south pole and badlands left) won't get me enough to push to Hypersonic Flight. 

Where should I go from here? My design creativity is running out, after the monstrosity that is the This Might Work. I still need to pull 300 more science from somewhere to push for Hypersonic, and that's ignoring everything else (I mean, I still don't even have reaction wheels). Any advice, whether on research or aircraft design, would be greatly appreciated.

This is a fun challenge I've done myself a few times, but it's not for the faint hearted :-)

    Ideas to consider -

Engine dropping designs - put the Panther engines in pods beneath your wings, and decouple them when they flame out.  This will greatly reduce the dry mass of the orbiter, and give you a lot of extra delta v.  It is still slightly cheaper than a rocket.    Underwing engines are easiest because they should be over your CoM, therefore no shift in the aircraft's balance as you decouple them.

^{Going to orbit on a stack of Junos and a Terrier}

Orbital fuel depot.  If your spaceplanes don't make it to orbit with enough fuel to reach another celestial body in one launch (unlikely, with Panther/Terrier tech),  then start building up a stockpile of fuel in orbit over several flights so that one day you can reach minmus.   An airplane with 4 sets of landing gear becomes  a cross between a car and a plane,   and can drive over most of the biomes of Minmus at high speed..

Spoiler

 

Airframe shedding.

Once you're in orbit, the wings etc are just dead weight that reduce your Delta V in interplanetary flight to airless bodies like Duna, and Mun.  You could do it permanently , with a decoupler,  or use a docking adapter like this

Having reached low orbit, all remaining fuel is transferred to the aft tank, and that section with the full tank, engine and cockpit be flown on to flybys of the Mun and Minmus.  You can then aerobrake back down, then re-dock with the spaceplane for re-entry if you want.    Or, just leave the thing up there and launch more planes to refuel it and exchange crew (if you're feeling kind).

If you're interested, this is what my "airplane only"  Mun mission looked like -

Spoiler

 

^{Jet engines now in a watery grave,  the "Saturn V" continues on Terrier power..}

^{In the upper atmosphere, it's time to let go of our side boosters}

^{In LKO,  it's time to park the airframe.}

^{Empty fuel tank is punched off the top shortly before touchdown on Tranquility Base.}

On our way home.  In the final staging operation, another fuel tank is discarded along with the science jr.  

 

 

[Jarin]

16 minutes ago, AeroGav said:

Once you're in orbit, the wings etc are just dead weight that reduce your Delta V in interplanetary flight to airless bodies like Duna, and Mun.

Yeah, I'd been trying to work that direction. The pictures probably aren't clear about how the This Might Work flies. If I can just grab a couple quick snapshots here...

Spoiler

Sort of a SpaceShipOne thing. 

Though I really need some sepratrons for that initial spacecraft release.

 

Regarding that Airplane-Only Mun Mission image set there, was covering the backs of your rocket engines actually notably helpful with drag, or was that mostly for style? I mean, an aircraft-only career is all about style, so it's a legit question. <.<

 

[AeroGav]

28 minutes ago, Jarin said:

 

  Hide contents

 

Regarding that Airplane-Only Mun Mission image set there, was covering the backs of your rocket engines actually notably helpful with drag, or was that mostly for style? I mean, an aircraft-only career is all about style, so it's a legit question. <.<

 

I am obessive about aerodynamic performance and when F12 aero forces display is on, I hate seeing those red lines coming off engine nozzles.   Though I am not sure how  much difference that really makes,  decouplers are scandalously expensive as you know.  My designs are fairly low powered and rely on good/lift drag ratio to succeed.  If thrust is 400% of drag in all phases of flight then i don't suppose it matters, but then you are probably carrying a lot of excess engine mass.   Then again,  that Mun vessel WAS overpowered in airbreathing mode, it had 4 Panthers for symmetry,  three would probably have been ideal.

BTW I'm impressed with your Virgin Galactic style offering.   I could only ever make that work with Whiplash engines, since the carrier needs to get on a sub-orbital trajectory as well, so that the upper stage can stabilize before the carrier falls back below 25km and gets deleted.  I've not really gone further into it, since it requires higher TWR on the upper stage than you'd otherwise pick, which eats up a lot of the gains (heavy engine, or chem instead of nuke)

[bewing]

Well, it would only take 250 science for you to get an MPL into orbit. With your rules, it sounds like one way to go is to make something that never has to come back down.

And your pic up there shows that you already have 532.3 science to spend -- so you're already there.

Go around, recollect all the Kerbin experiments, load it all into an MPL parked on the runway -- then launch the sucker with staging into LKO. That's what I'd do.

Edited October 28, 2016 by bewing

[Jarin]

1 hour ago, AeroGav said:

I could only ever make that work with Whiplash engines, since the carrier needs to get on a sub-orbital trajectory as well, so that the upper stage can stabilize before the carrier falls back below 25km and gets deleted.

Cheated my butt off here. The carrier tops out near 40km. I just switch back to the point of separation with FMRS (now that someone has a working 1.2 patch). I could theoretically make it work by pushing the orbiter into a high enough arc and retrieving the carrier before circularizing, but the timing there would be hell. Not to mention inefficient.

 

3 minutes ago, bewing said:

Well, it would only take 250 science for you to get an MPL into orbit. So that would reduce your total by 50. With your rules, it sounds like one way to go is to make something that never has to come back down.

... huh. And I could snag another set of mun-science to get it running better. That idea has potential. Getting an MPL to orbit in the first place is the real catch here. Waaayyy heavier than anything I've lofted so far. Not sure what it's going to take to build a heavy lifter plane pre-whiplash.

[bewing]

1 minute ago, Jarin said:

... huh. And I could snag another set of mun-science to get it running better. That idea has potential. Getting an MPL to orbit in the first place is the real catch here. Waaayyy heavier than anything I've lofted so far. Not sure what it's going to take to build a heavy lifter plane pre-whiplash.

Since it doesn't have to come back down, you can stage it like a normal rocket, so that should help a lot with the weight. I know for a fact that an upper stage that looks like this can make it to orbit, if you can get it above 40km and give it enough time to burn.

[Jarin]

Hm. Gonna have to blow some cash hiring staff too, to run the thing. Irritatingly, I haven't gotten a single rescue contract yet. I think I convinced it that all I wanted was tourist contracts, so now that's all it's giving me. 

[AeroGav]

https://kerbalx.com/AeroGav/flylab

It might be easier than you think,  I was surprised how easy it was to put a Hitchiker, Lab, and Cupola in orbit by just bolting wings and engines on the side. 

If you put it in a mk3 cargo bay then you need a huge SSTO.

Three way/four way adapter on the back with some terriers,  wings on the side,  and some drop-off panthers hanging underneath ?

edit - the above has two whiplash, two nerv, and a poodle (all carried to orbit).  An optimised version, the less ox and more lf,  gives you a bit more variety out the window

https://kerbalx.com/AeroGav/flylab2

[Jarin]

BEHOLD
The Packmule 1 is ready to fly!

Panthers dropped in sets of 2, with LV-909s underneath. I may swap these for T45s, since the lifter doesn't actually need to get itself clear to orbit. Keeps a single panther centerline for lifter return. Lab segment ditches the wings and wheels once it's free. Mostly copied @bewing for the lab component layout.

... I have no damn idea if this is going to work. Wish me luck.

1 hour ago, AeroGav said:

the above has two whiplash, two nerv, and a poodle

I would sell Jeb for a whiplash right now. Maybe toss in Bill for some Big-S wings.

Edited October 28, 2016 by Jarin

[bewing]

1 hour ago, Jarin said:

BEHOLD
The Packmule 1 is ready to fly!

 

... I have no damn idea if this is going to work. Wish me luck.

I would sell Jeb for a whiplash right now. Maybe toss in Bill for some Big-S wings.

Good luck! And don't forget to load the MPL with all the Kerbin ground experiments before you launch it!

[Jarin]

3 minutes ago, bewing said:

Good luck! And don't forget to load the MPL with all the Kerbin ground experiments before you launch it!

Oh crap, almost forgot to do that. I was just going to toss another mun flyby out for something to research. Didn't even think of ground science

[AeroGav]

Two Panthers and a Poodle,  it's actually rather sporty. We're definitely overestimating this task.  My initial idea of underslung engines ran into trouble - raising the wing to have the Panther exhaust  inline with CoM, caused the Poodle to be slightly below it once the Panthers departed, owning to the high mounted wing.   This caused an unpleasant pitch-up under power tendency in the upper atmosphere.

So, it was redesigned with wingtip mounted engines and a weird but slightly sci-fi looking split-level dihedral wing.   The rear engine cover gives the appearance of the ship from Firefly from some angles - or if you like your retro, Liberator from Blake's 7.

The lab section can in fact survive re-entry, but not a water landing, so i moved the wheels off the panther nacelles and onto the wings so we always have the option of bringing it home.

That said,  if I'm interpreting this correctly, Jarin is actually building a spaceplane tug (well, pusher design actually) for delivering bulky loads to orbit without the overhead of a mk3 bay.   Which is very cool and honest, I was planning to try something like this to deliver Duna base sections.  I've put the lab in orbit with a low starting mass, and it's mostly re-usable, but there's a fair bit of hardware tied up on that thing until we land it.  Jarin's tugboat can fly other loads while the lab orbits !

Ps.  My streamlining OCD says you could get lower drag by putting a rockomax adapter on the back of the lab so there's a proper transition from the 2.5m lab to the 1.25m of the front of that tug/launcher !

https://kerbalx.com/AeroGav/lowtec-flylab2

[Jarin]

39 minutes ago, AeroGav said:

Jarin is actually building a spaceplane tug (well, pusher design actually) for delivering bulky loads to orbit without the overhead of a mk3 bay.

That's the general idea. If I'm putting this much work into it, I'd like to have it work for other functions as well. Though if this model doesn't pan out, I'll probably steal your Flying Lab design there just to get the dang thing in orbit and figure out a proper lifter later.

The real trick is having CoL balance both with and without payload; thus the detachable wings on the lab. Haven't had a chance to test it yet though, beyond a short hop just to make sure it didn't spaz on liftoff. Will update after it flies for real.

46 minutes ago, AeroGav said:

Ps.  My streamlining OCD says you could get lower drag by putting a rockomax adapter on the back of the lab so there's a proper transition from the 2.5m lab to the 1.25m of the front of that tug/launcher !

I really need a wind-tunnel or something. I have no idea what changes actually assist with drag enough to offset the mass cost.

[AeroGav]

3 hours ago, Jarin said:

 

I really need a wind-tunnel or something. I have no idea what changes actually assist with drag enough to offset the mass cost.

Well, the right-click menu can be made to show the drag force on a part in kN, if you enable the option in the F12 menu.  

(Drag of Lab module _{without Rockmax Adapter} - Drag of Lab module _{with Rockomax Adapter}) - Drag of Rockomax Adapter = Drag Saving  (kN)

We can also work out how much drag is produced making the lift needed to offset the weight of this extra part 

(Mass _{Rockmax Adapter (Tons)}  x   Gravity on Kerbin ) / Lift:Drag Ratio of your vessel

The Rockomax adapter weighs 0.1 Tons,  Kerbin gravity is 9.81m/s²  ,  and my flylab had a L/D ratio of 2.7 in the screenie i posted , therefore

( 0.1 x 9.81 ) / 2.7  = 0.36kN

of thrust are needed to generate the lift to hold up the weight of this extra part.

There's tons of caveats,  but my hunch is that the numbers come out so heavily in favour of streamlining it's not worth worrying about them.

[Jarin]

I know that slopes on the front greatly reduce drag, but I wasn't sure about slopes on the back. I'll have to test it.

[AeroGav]

16 minutes ago, Jarin said:

I know that slopes on the front greatly reduce drag, but I wasn't sure about slopes on the back. I'll have to test it.

no difference between front and back of a part in terms of drag,  leaving the back end of a fuselage as a flat plate makes just as much drag as doing it to the front.

[Jarin]

Just now, AeroGav said:

no difference between front and back of a part in terms of drag,  leaving the back end of a fuselage as a flat plate makes just as much drag as doing it to the front.

that seems... really strange. You're sure about that?

[Jarin]

Okay, that might have been overkill. Lab is now in orbit with 2.2k dV left in the tank. Debating where I want to park the thing now. XD

Didn't quite get the lifter home, but that was mostly due to a stupid fuel imbalance, and me madly pumping everything into the forward tanks while spiraling backwards towards the water; engines on full burn to slow me down. Still, it recovered and got a goodly ways towards KSC before I put it down in the water. 86% recovery from a flubbed re-entry isn't half bad, I say.

[AeroGav]

Jarin,  you really need to put this up as a challenge, it's fun. Encourage people to share their aircraft on Kerbalx/Dropbox?

The new communications mechanic is making this mode of play slightly more viable.    The extra  launches to build out your comms network are a way to save money with your aircraft.

My first passenger SSTO, just sneaks inside the 30 part limit.  The layout keeps all fuel tanks around CG,  CG doesn't change fully loaded or dry.

https://kerbalx.com/AeroGav/Basic-Tourist-SSTO

I copied your "pusher" design, here it is launching an orbital fuel depot 

I also used it to launch the Kerbin SOI exploration vehicle , but at 3 tons,  we almost came to grief.  Total launch mass was just under 20 tons, that was pushing the  payload ratio margin,  2 panthers and 2 terriers (usable) is probably too many panthers for that weight.    We got above 70km, transferred all remaining oxidizer to the space vessel and just barely was able to circularise at 72km.   The launcher meanwhile was on a sub orbital trajectory due to hit the ground about 150 degrees east of the launch site.  I held 5 degrees AoA trying to stretch the glide,  skipping off the atmosphere four times, finally at 3km up I restarted the jets in dry mode, limping back on a sliver of throttle at 90m/s and 4x acceleration.    We finally ran out of fuel and put down on that big impact crater west of KSC , but only recovered 45% of the value due to distance :-(

I then realised that most of the payloads had their own engine.   A tractor design would allow that to be used, and allow us to bring more LF/Oxidizer tanks.

After delivering a payload, Val unloads her spare fuel to Jeb's lander.   There's something vaguely suggestive about the way these things are docked - Shipper alert !

The 4 tourists wanted a Munar flyby, and I also had a contract to land on the Mun.  So, the fuel depot, lander, and hab got docked together and departed on a free return trajectory mun encounter.   At periapse, the fuel depot and jeb's ship separated and performed a capture burn, then jeb undocked and went down and came back up from the surface.   That's an Apollo-style mission, right? (apart from the tourists)

The next mission is a big one, putting the science lab in orbit.  I've come up with some improvements to the "tractor" though.   Since we need more dry mass up front, i'll take the two terriers and clip them into the panthers on the outboard nacelles.  The inboard nacelles will be fuel only.

In difficulty options, I'd unchecked "extra ground stations",  so I needed to deploy some of those as well.   I needed an aircraft that could supercruise but would also be stable on autopliot when time accelerating.

https://kerbalx.com/AeroGav/Bute-Ranger

The wings are angled up with 5 degree incidence and 5 degree dihedral. So, it will fly if you just set prograde assist, it also cuts down on mk2 fuselage drag since it's at zero angle to the airflow.  The downside is that if you try to fly fast down low, it keeps trying to climb and go into a loop.  Once at altitude it's a "hands off" aircraft though.   There's a couple of strakes at the back that aren't angled.   If the AoA rises above zero, they start generating lift and will push the nose back down.

Cruisin'.   

I made an action group to open the bay doors and release the docking clamps on the cargo.  Unfortunately this usually damages is.   Which is a pity as the thing sits so low down, it wriggles and squirms as the bay doors open, and really looks like it's laying an egg.     Can also be used to scoop objects off the ground - damaging them further in the process.

Edited November 6, 2016 by AeroGav

[Jarin]

18 hours ago, AeroGav said:

you really need to put this up as a challenge, it's fun

I might still. I've got enough screenshots to post mine, even if it's not done yet. I'm not sure if it's something that fits the normal challenge format, though. What's the finish condition? Completed tech tree? Bonuses for worlds reached? Mission scores for 100% reusability? 

[Plusck]

On 07/11/2016 at 4:48 AM, Jarin said:

I might still. I've got enough screenshots to post mine, even if it's not done yet. I'm not sure if it's something that fits the normal challenge format, though. What's the finish condition? Completed tech tree? Bonuses for worlds reached? Mission scores for 100% reusability? 

Keeping it simple: "Wings-only route to the RAPIER".

I think the Rapier as finish condition would be the first standard (since to get it you'd need to unlock a lot of the tech tree underneath it). You could add higher achievements, but the Rapier seems to me to be the major hurdle.

Rules to keep it simple could be simply never to upgrade VAB/launchpad and/or never to use them (keeping it on trust) and/or to destroy them both deliberately as soon as possible (manned bombing run or inverted SRB as soon as the first probe core is unlocked - radical and ugly but could be seen as a badge of honour).

[AeroGav]

1 hour ago, Plusck said:

Keeping it simple: "Wings-only route to the RAPIER".

I think the Rapier as finish condition would be the first standard (since to get it you'd need to unlock a lot of the tech tree underneath it). You could add higher achievements, but the Rapier seems to me to be the major hurdle.

Rules to keep it simple could be simply never to upgrade VAB/launchpad and/or never to use them (keeping it on trust) and/or to destroy them both deliberately as soon as possible (manned bombing run or inverted SRB as soon as the first probe core is unlocked - radical and ugly but could be seen as a badge of honour).

I'd prefer full unlock of the tech tree , that way you actually get to fly some craft with those lovely RAPIERs you worked so hard for.  It's not much extra grind,  in my experience once whiplash/nuke are available,  you can go pretty much anywhere and progress is rapid.    The sticking point for me was getting the funds to upgrade the R&D to level 3  - without which, you've stuck with panther/terrier designs no matter how much science you've got banked.

As an optional condition, upgrade runway, hangar, mission control and admin buildings to top level .  Use your long reach and reusable vehicles to get the money quickly.

Edit. My 1.2 career game is finally ready to move into the big league.

 

40 ton takeoff weight, two panther, three terriers to put this lab up in orbit.  I've been saving data from our Mun and Minmus excursions for the lab to process.   We FINALLY we have the 1.6 million Kredits to upgrade R&D.    Our scientists hitched a ride on the final tourist mission to Minmus to level up , no more damn tourists for a while !  Also, only two more infernal docking maneuvers to perform :  I got to retrieve the tourists & scientists from low orbit, then fly the scientists back up  to the lab once they ding.

And finally I can design a proper spaceplane with whiplash, aerospike, and nerv technology and see where it can go !    

Edited November 8, 2016 by AeroGav

[Jarin]

3 hours ago, Plusck said:

"Wings-only route to the RAPIER".

 

2 hours ago, AeroGav said:

I'd prefer full unlock of the tech tree , that way you actually get to fly some craft with those lovely RAPIERs you worked so hard for.

Current career status: Got a contract to test the Rapier on escape velocity from Minmus. Yeeah, I think I'll just accept that and put it on the back-burner for a bit.

Contractor: "Are you sure you're testing that engine for us?"

Jeb: "Yep! This LKO cargo carrier is totally headed for Minmus. I'm sure it'll get there this time!"

Edited November 8, 2016 by Jarin

[AeroGav]

Yeah finally, Whiplash engines.  Also pre-coolers and Aerospike on same tech node.    It's the first time I actually used a lab, didn't realise they take so long to process the data or i might not have loaded all my mun samples on the thing.  Jam today, jam tomorrow and all that.   Ended up warping forward 6 months to unlock the Whiplash,  then couldn't think what I could use a Whiplash/Dart spaceplane for that i couldn't already do.  Warp forward a few more months, process more science,  and we have nukes too.

A late night session eventually produced the above craft.  I think I was fed up of the very Kerbal looking spindly mk1 devices i'd used up till now.  That weighs 50 tons fuelled but with an empty cargo bay.  2 Whiplash, 2 nukes and  one Dart aerospike   Gets to orbit with about 1/3 of its LF remaining, which is fairly considerable (the sponsons on both sides of the mk2 fuselage are just a string of mk1 LF tanks).

What to do with it?    Ike?  Gilly?  Duna itself?    or just use it as a cargo ssto, put some probes out there?

I've never kept a career game going so far.  At first I thoght it was normal waning enthusiasm, but more likely i'm just not sure how to proceed.  Launching missions and not having them arrive for 2 years.  Forgetting the antenna and having to wait 4 years to the  next launch window.  Euch.  

Maybe take a look at Kerbal alarm clock.

I was quite excited to build this, I've not used that combo of engines before.  It falls into the seldom charted waters between the ultra low tech  stuff you have at the start of a career playthrough and the bleeding edge, min-maxed things we put together in sandbox.