Kerbodyne SSTO Division: Omnibus Thread

[Wanderfound]

It helps to remember that control surfaces are levers; the further they are from CoM, the more power they have. Ditto for horizontal & vertical stabilisers. Therefore: long fuselage for pitch and yaw stability.

As for wing size...in FAR, take your inspiration from reality. Sure, 747's have big wings, but they don't go at Mach 5 and they don't go to space. These planes do (almost):

Notice the lack of big wings?

[m1k3ol]

This is true even for stock isn't it?

Or is there anything that would complicate those designs?

BTW, hope you're doing better now!

[Wanderfound]

This is true even for stock isn't it?

Or is there anything that would complicate those designs?

In FAR, take your cues from reality. In stock, try not to trip over reality's rotting corpse as you step past it. For a nice demonstration of just how little influence real aerodynamics have on stock, see http://forum.kerbalspaceprogram.com/threads/93779-SSTO-Spaceplane-Airplane-Design-Contest-II-Akademy-Awards?p=1416715&viewfull=1#post1416715

Stock aero planes typically carry more wing, more intake and more engines. However, I'm not the person to ask for stock design tips; I don't do that often enough to give good advice. Checking out some of the stock aero planes in the Akademy Awards thread should be useful, though.

[Jovus]

eddiew, I was running into the exact same problem once upon a time before Wanderfound helped me out. (You've definitely come to the right place; this man is a gift to KSP's spaceplane designers.)

What manifests itself as a lack of lift problem is almost certainly actually a lack of thrust problem. Put more engine on that bad boy. (And possibly less wing, though don't screw up your low-atmo low-velocity performance.)

[m1k3ol]

In FAR, take your cues from reality.

Any way to get something similar to the Lockheed Hopeless Diamond?

http://www.hitechweb.genezis.eu/stealth2.files/lockheed_hopeless_diamond_01.jpg

By "similar", I mean that "at least" the wings are sorta "triangular", if the full body can't be done

(yeah, I usually like a "lifting body" craft)

I've been trying my luck with it (stock parts, pending my test with FAR, seems to be ok) but it seems I haven't got a clue yet on where to get any control surfaces...due to the triangular wings...

At least the plane flew by the end of the runway! (Even if I couldn't use pitch properly)

Edited November 14, 2014 by m1k3ol

[eddiew]

eddiew, I was running into the exact same problem once upon a time before Wanderfound helped me out. (You've definitely come to the right place; this man is a gift to KSP's spaceplane designers.)

What manifests itself as a lack of lift problem is almost certainly actually a lack of thrust problem. Put more engine on that bad boy. (And possibly less wing, though don't screw up your low-atmo low-velocity performance.)

Short version; quite right. Unfortunately I'm limited to RAM intakes at the mo, which makes my engines choke at ~20km altitude with one intake each. They'll make 25km with two each, but then the drag keeps my speed down and it's even harder to get anywhere. Rapidly turns into a race of engines vs intakes, but the best balance I can find for this size of craft is a pair of each.

However... basing my design on one of Wanderfound's more compact models, running with 2x RAMs, 2x regular turbojets from Karbonite, and 1x nerva, I actually managed to get the little beast into orbit, rendezvous with the lost kerbal, and bring him home. Despite having cannily covered the crew hatch with a radial parachute. Misjudged the final approach and landed about 200m from the runway via those emergency parachutes, but the exploding nerva triggered a nearby seismometer and gave me science, and I was able to taxi onto the runway for nearly full recovery costs anyway. In kerbal terms, that's a 110% success!

Handled pretty well throughout; as long as the AoA stayed under ~15 degrees, she was happy to bring herself back to prograde and just descend gently. Whether she'll make orbit with something in the cargo bay I'm less certain... maybe if I dump all the mono prop to free up the weight, but I doubt she'll carry more than a ton above her current mass. Landed with about 600 m/s left in the nerva, but it was a super tight thing getting out of the atmosphere. Tempted to sneak a couple of structural type B's behind the main wings - no new leading edges, so maybe FAR will let me have the lift without penalising me with drag?

Either way, it's definitely better than this...

...which constantly, and predictably, fought the controls going both up and down and very nearly didn't make it to space. And yes, that's 18 intakes per engine, and some LV-909s on the back. (Though indeed, the Mad Spaceplane Dragonflight somehow made it up to 76km and deployed its satellite by ejecting it violently out of the back end since I didn't have cargo bays at the time. Couldn't make a full orbit though, so had to be quick about it!)

So yeah, thanks Wanderfound and Jovus, you've definitely put me on the right track and hopefully I can avoid further catastrophes of design

[Wanderfound]

Any way to get something similar to the Lockheed Hopeless Diamond?

http://www.hitechweb.genezis.eu/stealth2.files/lockheed_hopeless_diamond_01.jpg

By "similar", I mean that "at least" the wings are sorta "triangular", if the full body can't be done

(yeah, I usually like a "lifting body" craft)

I've been trying my luck with it (stock parts, pending my test with FAR, seems to be ok) but it seems I haven't got a clue yet on where to get any control surfaces...due to the triangular wings...

At least the plane flew by the end of the runway! (Even if I couldn't use pitch properly)

You can get that sort of shape to work in stock, but you'd struggle to make it fly well in FAR (because you'd need to fake that wing shape by stacking layered wings together, which FAR will interpret as a badly constructed biplane rather than a single funny-shaped wing).

You can definitely do lifting-body ships in FAR, though. But you need to do it by using body parts with lift (e.g. Mk2 fuselage pieces), not by hacking something that looks vaguely appropriate together from repurposed parts. See the Kerbodyne Lancer for an example.

As for control-without-control-surfaces: hard, but possible. Lockheed (and B2 bombers etc) do it by the use of differential thrust: basically, if the plane starts yawing right, the flight computer cuts the left engine's thrust a smidgeon. This is possible to do in KSP, but very very very difficult.

The easier way to approximate it would be via heavy use of Vernors and lots of SAS torque. Alternately, get super-cheaty and use part clipping to hide some control surfaces inside the wing (this will work in stock, not sure about FAR).

[m1k3ol]

Yeah, hiding it was the only option I was actually considering, and yes I'm going full mk2 pieces

I will certainly check the Lancer!

[blowfish]

Using specific parts for body lift doesn't matter with FAR. FAR models body lift for all parts and the stock ModuleLiftingSurface hack for the Mk2 parts is removed.

[Wanderfound]

Using specific parts for body lift doesn't matter with FAR. FAR models body lift for all parts and the stock ModuleLiftingSurface hack for the Mk2 parts is removed.

Okay, cool; wasn't sure about that.

Mk2 bits do make good lifting bodies, though; they've got the shape for it.

[blowfish]

Okay, cool; wasn't sure about that.

Mk2 bits do make good lifting bodies, though; they've got the shape for it.

IIRC FAR models everything as a conic frustum though (unless custom parameters are given), so the fact that they are wider and flatter won't actually matter.

[Wanderfound]

IIRC FAR models everything as a conic frustum though (unless custom parameters are given), so the fact that they are wider and flatter won't actually matter.

Hmmph.

Okay, ignore what I've been saying about lifting bodies, then.

[peachoftree]

It helps to remember that control surfaces are levers; the further they are from CoM, the more power they have. Ditto for horizontal & vertical stabilisers. Therefore: long fuselage for pitch and yaw stability.

Is there a way to make a plane that can fly at low enough speeds to land on surfaces other than the runway and also be able to fly at the speeds necessary for a spaceplane?

[Samskiing]

Wanderfound, I wanted to thank you for your designs. They helped motivate me to get ambitious with my spaceplanes, instead of just making little single-seaters in Stock Aero.

Edited November 19, 2014 by Samskiing

[blowfish]

Is there a way to make a plane that can fly at low enough speeds to land on surfaces other than the runway and also be able to fly at the speeds necessary for a spaceplane?

Yes - make it small, give it a wide wheelbase, and pick as flat a landing location as you can.

[Wanderfound]

Is there a way to make a plane that can fly at low enough speeds to land on surfaces other than the runway and also be able to fly at the speeds necessary for a spaceplane?

Many ways.

For some examples, see http://forum.kerbalspaceprogram.com/threads/90747-Kerbodyne-SSTO-Division-Omnibus-Thread?p=1527285&viewfull=1#post1527285 and http://forum.kerbalspaceprogram.com/threads/97802-Fun-with-IVA-reentry-(lotsa-images) and http://forum.kerbalspaceprogram.com/threads/90747-Kerbodyne-SSTO-Division-Omnibus-Thread?p=1504987&viewfull=1#post1504987 for a few different ways of doing it.

If you're not going VTOL, it's more about post-touchdown stability rather than super-low stall speed. So, wideset gear, good ground clearance, tailstrike guards. And possibly retrothrust for emergency braking: RCS and Vernors for the reasonable version, Sepratrons for the extreme version.

[blowfish]

Parachutes may also do the trick, assuming they don't torque the ship in the wrong direction.

[Wanderfound]

Parachutes may also do the trick, assuming they don't torque the ship in the wrong direction.

Keep in mind that stock parachutes will detach as soon as your wheels touch ground, however. If you want proper landing drag chutes, you need the Realchutes mod.

[davidpsummers]

All my planes landed fine on the grass around the runway at KSC. I generally find any "grasslands" to be suitable, though I haven't tried the extensively.

I also have enough parachutes so I can land that way (in case my craft can't make it to a good landing place or something goes wrong).

[Engineer of Stuff]

Can you make a replica of the Delta-Glider from Orbiter?

Edited November 19, 2014 by Engineer Of Stuff

[Wanderfound]

Can you make a replica of the Delta-Glider from Orbiter?

http://www.orbiterwiki.org/images/5/5f/xr1-top-cropped-800.jpg

I can build something with that basic airframe shape (i.e. a lifting body delta with wingtip vertical stabilisers), sure. What do you want it to be able to do? That image looks like a pure rocket rather than the usual spaceplane jet/rocket hybrid. Is that factor important?

[davidpsummers]

All my planes landed fine on the grass around the runway at KSC. I generally find any "grasslands" to be suitable, though I haven't tried the extensively.

I also have enough parachutes so I can land that way (in case my craft can't make it to a good landing place or something goes wrong).

BTW, if you can't go slow enough to land on grass, the solution is bigger wings. More lift means you can fly more slowly. Of course big wings have the obvious limitations.

[Somtaaw]

been trying my hand at spaceplanes, and while I'm not quite ready to start installing FAR/NEAR, or other mods to get a more realistic play, I think it's still worth putting in my request for what I am trying to build.

Recently started toying with ExtraPlanetary Launchpads, and looking at some of my existing craft, some of which I've gotten from here. One of which is perfect for replacement by the Economic Boom release.

http://forum.kerbalspaceprogram.com/threads/51003-Oops Horizon Heavy Industries O.O.P.S. [On Orbit Personnel Shuttle], could be easily replaced by a space plane, to fill the same role, of being able to pickup and move Kerbals around, but also give me a potentially good "lander" to boot. It comes with 350 energy, 40 units of mono, and 169 & 207 of LiF and Oxide respectively.

I'm looking to get some feedback as to my design thoughts, from the master. It's intended to be built in space, operate primarily in space as a shuttle, and ability to land on Kerbin. Subsequent takeoff from Kerbin is classed secondary in importance. RCS thrust is very well balanced so far, although I have yet to actually try and fly it yet.

Edited November 19, 2014 by Somtaaw

[Wanderfound]

Happy to help, but it looks like you're flying in stock aero. I'm much more useful for FAR.

[Somtaaw]

I prefer to avoid using FAR, if I'm only landing on Kerbin as a last resort; unless you think it's one of those "you cant play KSP without it" type of mods.