Kerbodyne SSTO Division: Omnibus Thread

[Wanderfound]

I'd be interested in seeing your design process, building a new bird given a specific goal; e.g. something that can do multiple Kerbin landings for local surveys, get to LKO with a 2t cargo in the least time, or run a round trip to Mun with a science package

Though I suspect I won't be in the right time zone to watch live, so I'll have to wait for the youtube version ^^;

Coincidentally...

Spot the two mistakes.

Edited January 20, 2015 by Wanderfound

[eddiew]

Lol, I noticed that on your channel right after I posted here. I'll see if I can give it a watch in my lunch break

[WhiteKnuckle]

I was thinking of weight penalty vs circular tank alone, relative to circular tank + cargo bay. If I'm carrying 1.25m tanks, I tend to mount them like this:

The Mk2 fuselage parts are less weight efficient than the 1.25m tanks, but they do provide more lift. I tend to find that ships that make heavy use of rocket parts struggle to gain sufficient lift, whereas ships with plenty of Mk2 fuselage can get away with less wings.

Yup I agree that mounting round tanks to the side is the way to go, but like your's most of my designs have a central Mk2 body. And if you're going to do that I can't see any reason not to use the tank-in-bay trick. So using this pic as an example, I'd swap out the Mk2 LF/O tank behind the crew can and the one just before the tail for cargo bays with fuel tanks in them. Should be the best of both worlds.

Gonna watch your videos now.

[Behemoth1702]

Wanderfound, any chance you could make yourself (and for some keen customers) a space shuttle? I know you're the plane guy but someone with so much knowledge about aerodynamics could probably produce a very amazing space shuttle!

I know FAR has one but I wonder what you would come up with!

Would be great material for a YT vid as well I believe, since space shuttles are so fascinating to the KSP community it seems.

Thanks in advance!

[Captain Sierra]

Is it just me, or does Wanderfound sound just like Kofeyh?

[eddiew]

Actually as far as videos go, Wanderfound, I'd love to see what you could make with B9 parts, even if you don't want to play with them in your own game time. It's a struggle to find quality, aesthetic designs using B9; reckon there's a niche to fill there. Could also check out SXT for a bunch of new cockpits of various dimensions, something to add variety to the front end of your birds.

Just a thought, might give you some scope for videos beyond the ol' MK2

[Wanderfound]

The test-flight sequel to the Demonstration Gull build video! Now in higher resolution!

I should have a higher-res version of the build video up in a while as well.

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Higher-res version of the build video:

[KerBlam]

Hey Wanderfound.

I hope you're feeling better!

I love all your designs man! Awesome stuff.

I think I've been reading through this thread for about 2.5 hours now, and I got to page 30

Just out of curiosity, what would be your suggestion for a relatively easy to learn spaceplane that carries a decent LFO payload, and a bit of cargo? I'd like to start there.

I'm playing .90 with FAR... If you could suggest a link with a how-to for the action groups and a craft file, I will keep you updated on my progress (with screenies of my explodey good times)

Thanks man! Excellent work.

[Wanderfound]

Hmmn...

It depends a bit on if you're playing Career with limited tech.

Most of the Gull/Skua/Simplicio/Bushranger/Investigator variants are good, easy to fly and practical light cargo spaceplanes. However, they were all built in .25, so they may need a tiny bit of tweaking for .90. They'll probably work okay, though; the major change in aero from .25 to .90 was the enhanced skin drag, which doesn't affect design too much.

Of the recent batch, the Alkahest (http://kerbalx.com/Wanderfound/Kerbodyne%20Alkahest) was designed specifically as a low-tech option. Replace the cargo bay with another fuel tank and it should be good for what you're after. Or, for something a bit more high-tech, check out the Stratos N (http://kerbalx.com/Wanderfound/Kerbodyne%20Stratos%20N). As an in-between option, have a look at the Sledge (http://kerbalx.com/Wanderfound/Kerbodyne%20Sledge).

But if you're new to FAR piloting, what you really want to do is grab a light atmospheric aircraft like the Kerbotrainer (http://kerbalx.com/Wanderfound/Kerbotrainer) and take it for a spin. Take it up top and see how fast and high you can get it, pull it back down into the mountain passes and try some high-G aerobatics, etc.

Astronauts start with test pilot training for a reason.

-

With the older stuff, you'll have to take it into the SPH and look at the action groups yourself. Newer things that are mirrored on KerbalX (http://kerbalx.com/Wanderfound) have their action groups listed there.

[KerBlam]

Thanks for that.. I really just want to try to get a spaceplane into orbit, for station refuelling.

I have been playing with the Kerbotrainer a bit, trying a few challenges... I seem to have some trouble keeping the wings on. so much so that I've started wondering if my FAR install is borked, because sometimes they come off even on the slightest manoeuvre at low speeds i.e around 150m/s.. I think I'm being pretty soft on the controls... I don't know. I'm still feeling it out. Have you ever heard of that being an issue with a bad install?

I

[eddiew]

Interesting vids so far, cheers Wanderfound. Nice to see that even your planes get a bit squirrelly at 30km as well - thought it was me doing something wrong with the stuff I've put together

Can I suggest that you title your videos something like 'KSP 0.90 SSTO Spaceplane to Orbit'? It'll make them findable to people who are just browsing youtube for kerbal spaceplanes - right now it'll probably not show up in their searches, which would be a shame

Also... rapiers vs turbojets. In my SPH, both read about the same weight and thrust, but you clearly favour having a mix of both - just wondering if you could enlighten me as to why? I feel like there's some sneaky secret I don't know about ^^;

[Wanderfound]

The obscure titles are a bit deliberate; I'm still working out what I'm doing, so I don't want too many folks seeing my early screwups...

Compared to airbreathing RAPIERs, Turbos provide slightly better thrust and substantially better fuel efficiency. Mostly, however, they just sound a lot nicer.

Also, however: a very effective design is one central Turbojet flanked by RAPIERs. You keep the Turbojet on until it dies, making the most of the oxidising RAPIER-driven ram-air effect. By the time the Turbo dies and a RAPIER there would become useful, you've usually already got the Apoapsis to 70km or so.

[CrisK]

Wanderfound, I'm glad that I stumbled across your thread! Your designs are excellent.

Is lift the only reason that you prefer the MK2 parts to round tanks? I ask because I'm trying to improve my own plane design.

[Wanderfound]

Thanks for that.. I really just want to try to get a spaceplane into orbit, for station refuelling.

I have been playing with the Kerbotrainer a bit, trying a few challenges... I seem to have some trouble keeping the wings on. so much so that I've started wondering if my FAR install is borked, because sometimes they come off even on the slightest manoeuvre at low speeds i.e around 150m/s.. I think I'm being pretty soft on the controls... I don't know. I'm still feeling it out. Have you ever heard of that being an issue with a bad install?

Most likely problems:

1) Are you using a PID tuner such as the one in Kerbal Pilot Assistant? Stock SAS will tear the wings off most things.

2) What altitude? Things that are safe to do at 5,000m are often suicidal at 500m.

3) Is it the latest version of FAR? Prior to the introduction of the mass/strength tweakable for wings (around when KSP .24 was released), FAR wings were eggshell-fragile; about equivalent to 0.25 on the tweakable.

4) Tap the controls, don't hold the buttons down. Watch the G-meter. Regardless of speed, 20G is 20G. That said, Kerbotrainer ​was built for aerobatics. It should be fine with anything below 10G, and can handle much more than that if flown right.

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Wanderfound, I'm glad that I stumbled across your thread! Your designs are excellent.

Is lift the only reason that you prefer the MK2 parts to round tanks? I ask because I'm trying to improve my own plane design.

1) I built a lot of Spaceplane Plus stuff before it was stockified, 'cos Porkjet makes good parts.

2) Cargo bays are useful.

3) Mk2 cockpits have a very pretty RPM IVA.

But lift and density play a role as well. Apart from very small things like the Aero R, planes that make heavy use of 1.25m parts tend to need very large wings.

[KerBlam]

Yeah I'm using the PID tuner that is with Pilot Assistance, If I have it set up right is another thing... edit: Also latest FAR.

It happens randomly at various altitudes seemingly, the other thing that happens is the plane will just lose control and spiral into the ocean without hope of recovery. That also happens at any altitude, just now it happened at 26000m and 800+ m sec... Like a flatspin, but I wasn't trying to manoeuvre at all, it just *went* and no way I could regain control. I've even tried with an xbox 360 controller to see if analogue controls help, but I get the same thing.

I'm not a pilot, but I've flown quite a lot of flight sims, and never came across these kinds of issues before. I really hope it's not just me!

Edit: Some progress, seemingly after removing FAR, deleting the FAR folder from my gamedata folder, then reinstalling, the strange loss of control thing has stopped, so I think that was just a dodgy install.

However, I'm not convinced the G-force readings I'm getting are right. They seem pretty extreme. Example, in the Kerbotrainer.

Straight after takeoff, I dropped the throttle to about halfway, climbed to 2500m and then SLOWLY rolled and turned to 270 degrees, got to the mountains, SLOWLY turned around to 90 degrees, turned throttle off to coast in to land. I'm doing about 300m/s at this point so I slowly roll and try to wash some speed off. I barely have to touch the stick and I'm G-ing in the red. so I'm doing everything super slow and gentle. I roll slightly too far, overcorrect a fraction and the wings have left the building. Fireballs and mayhem. It doesn't seem right at all.

Edited January 21, 2015 by KerBlam

[Wanderfound]

Yeah I'm using the PID tuner that is with Pilot Assistance, If I have it set up right is another thing...

It happens randomly at various altitudes seemingly, the other thing that happens is the plane will just lose control and spiral into the ocean without hope of recovery. That also happens at any altitude, just now it happened at 26000m and 800+ m sec... Like a flatspin, but I wasn't trying to manoeuvre at all, it just *went* and no way I could regain control. I've even tried with an xbox 360 controller to see if analogue controls help, but I get the same thing.

I'm not a pilot, but I've flown quite a lot of flight sims, and never came across these kinds of issues before. I really hope it's not just me!

If you can, post screenshots or vid of it losing control at various altitudes and speeds. Was the plane stalling at the time? Do you get similar results if you build a small plane yourself?

Until you've got the hang of it, keep the AoA below 15°. If the SAS was on and tuned right (use stock SAS mode, cut all kp to 1/3 default, clamp to 1/2 default) and you weren't flying at extreme AoA, the only thing that should make it spin is lack of airspeed (<100m/s in a low altitude climb, much less if flying flat) or asymmetric thrust on a multi-engined plane. Unless you've somehow managed to drain the batteries...

Use the FAR window or Kerbal Flight Data to watch for stalls. Back off on minor stalls until the stall stops, immediately recover to prograde on major stalls. That's the spin recovery technique as well; get the nose to prograde and gradually pull out.

Without more data, I'm not sure what's going on.

[KerBlam]

Apologies see edited post above

[Wanderfound]

You may still have some install problems, but: 300m/s is transsonic, i.e. faster than a Spitfire in a flat-out power dive. That's not something you want to be doing at less than a few thousand metres of altitude until you've got the hang of it. If you're getting dynamic pressure warnings from FAR or Kerbal Flight Data, fly with caution.

Can you define what you mean by "touch the stick"? At that speed and altitude you should be tapping the keyboard, never holding down the pitch controls. Control input intensity by varying tapping rate.

Does using Fine Controls (capslock key) improve things for you? They're not necessary, but they may help.

Edited January 21, 2015 by Wanderfound

[KerBlam]

By 'touch the stick' I mean the analogue stick on an xbox controller. I get better fine control that way, and have been able to fly somewhat more successfully than I could using the keys. I was using the capslock function with keys. I have the sensitivity set to 'numb' which means I can perform pitch adjustments very smoothly.

It seems quite random, as sometimes I can do a proper balls-out manoeuvre without having a problem, only for the wings to come off while I'm going relatively straight or make a small adjustment the G-forces will spike into the red and kaboom.

It's pretty frustrating... I'm sorry to be spamming your thread with this honestly, but you seem knowledgable and have helped.

[Wanderfound]

My first suspect would be the XBox controller, to be honest. KSP is notoriously finicky for joysticks.

Lowering the max deflection on the control surfaces and beefing up your wing mass a bit may help.

[Rakaydos]

Do you have any "Mid tech" (no 500 science part) orbital refueling spaceplanes for FAR?

[KerBlam]

SO! I finally managed a loop n land! (After 3 or 4 touch n go's)

Where I was going wrong was; too much throttle. Basically have to drop the throttle to about 5% straight after takeoff, and feather it for manoeuvres. Turn it off BEFORE I start my descent loop and wash speed in the turn to around 100m/s... I think I've got this now. If I get a bit gung-ho on the throttle the wings will let me know, by leaving the party.

With that said, it feels strange that such a small plane would be so difficult to slow down on the runway. It takes nearly 3/4 of the strip to stop with the brakes locked. It's freaking me out thinking of getting a large one stopped.

With the PID adjustment, I'm not seeing any adjustment for 'clamp'. There's Kp Ki Kd and Scalar.. Is Scalar 'clamp'?

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[FleshJeb]

Just watched the Gull vids--The insights were great, but the failures were fascinating. I can't run FAR (I'm already lagging above 75 parts), so it's really interesting to see how it all works.They could do with some editing or time compression. (I realize that's more work for you). That said, having the whole mission in real-time allows a lot more detailed and interesting commentary.

--"The next minute or two would have had to be entirely language-filtered."

--Jebediah's PTSD

--"The metaphysical nature of Kerbal resurrection"

[Wanderfound]

Yeah, I realise they run on a bit. The ones I'm doing today are getting edited down; I recorded an hour-long commentary, then realised that it sucked, so I cut the vid down to 30 minutes and I'm about to redo the voiceover.

I'm new to the whole DIY video thing; the last time I recorded video involved a TV crew.

Glad y'all are liking them, though.

What's better: building, flying, or building then flying?

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SO! I finally managed a loop n land! (After 3 or 4 touch n go's)

Where I was going wrong was; too much throttle. Basically have to drop the throttle to about 5% straight after takeoff, and feather it for manoeuvres. Turn it off BEFORE I start my descent loop and wash speed in the turn to around 100m/s... I think I've got this now. If I get a bit gung-ho on the throttle the wings will let me know, by leaving the party.

With that said, it feels strange that such a small plane would be so difficult to slow down on the runway. It takes nearly 3/4 of the strip to stop with the brakes locked. It's freaking me out thinking of getting a large one stopped.

With the PID adjustment, I'm not seeing any adjustment for 'clamp'. There's Kp Ki Kd and Scalar.. Is Scalar 'clamp'?

http://imgur.com/a/uvmhx

Yup, clamp = scalar. I'd try kp's of 5000 for pitch and 3000 for roll, BTW. KPA has a glitch that switches the preset values around occasionally.

The Kerbotrainer​ is particularly bad at ground braking. There are only two braked wheels, and there's barely any weight on them. I left it that way on purpose to encourage people to learn to hit the start of the runway rather than midway down.

To improve its ground braking:

* Reenable the front brakes. You need to be careful not to overdo it and dig the nose in if you do this, though.

or

* Set the inner ailerons as spoilers linked to the brakes.

or

* Stick a pair of Monoprop engines pointing forwards at the wing roots. Set an action group to toggle them. Make sure that the cockpit has its monoprop supply full.

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Do you have any "Mid tech" (no 500 science part) orbital refueling spaceplanes for FAR?

There are only a few big tankers here, and they're all fairly high tech. But if you take a Wedgetail and swap the engines for a mix of Turbojets and LV-T45's, it might work.

[Jovus]

Or instead of monoprop engines, sepratrons. Because who doesn't love RATOL?