Kerbodyne SSTO Division: Omnibus Thread

[Wanderfound]

I can't be sure what's happening without experimenting, but this is how I'd go about it.

1) Replicate the test flight conditions. Deactivate all FAR flight toggles, activate SAS, install Kerbal Pilot Assistant and switch it to stock SAS mode, use the included PID tuner to cut all kp values to 1/3 of default and scalars to 1/2 default.

2) Don't touch the controls until the aircraft is up to take off speed, unless you need to correct for a low-tech runway pothole (best to do the testing in Sandbox, though).

3) If the problem reoccurs, make sure that the steering is unlocked on the front gear only. Check each wheel, don't rely on symmetry.

4) Do a takeoff run with the view swung around to below the nose looking back. Watch the wheels; check to see if they wobble, and if so, which one first. Check if it's consistent; landing gear problems are often intermittent. Look for flexing in the surfaces which the gear are mounted to. Reinforce or relocate wobbly bits.

5) If it veers without wheel wobble, do another run and watch the aero surfaces to see if they're doing anything weird.

6) If nothing else works, pull the entire aircraft into component bits and make sure that angle snap is on when you rebuild it.

Eddie: KSC-> Mun -> KSC unrefuelled can be done, but it doubles the size of your ship and makes it painful to fly. You need a big lumbering beastie for that sort of range. With a refuel, you can do it in a sportscar.

[Wanderfound]

Kerbodyne VTOL Trainer. A combination fast jet / aerobatic / VTOL trainer.

A toy for veterans, educational for novices. Hugely fun to fly in either mode; capable of some truly ridiculous trickery when all engines are combined.

Craft file at https://www.dropbox.com/s/66dmrzs7vk3vvn4/Kerbodyne%20VTOL%20trainer.craft?dl=0

Edited February 5, 2015 by Wanderfound

[WhiteKnuckle]

OOooohh. I'm gonna have to take that for a spin when I get home. Since I've got something comparable, I'm interested to see how they stack up.

[KerBlam]

Hey Wanderfound!

So I took your Alkahest SP4 on a mission to Minmus, to deliver a ScanSat and some crew to my orbital station. I thought you might enjoy a look.

Great plane! I like it a lot. Thanks!

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[lordcirth]

1) Replicate the test flight conditions. Deactivate all FAR flight toggles, activate SAS, install Kerbal Pilot Assistant and switch it to stock SAS mode, use the included PID tuner to cut all kp values to 1/3 of default and scalars to 1/2 default.

2) Don't touch the controls until the aircraft is up to take off speed, unless you need to correct for a low-tech runway pothole (best to do the testing in Sandbox, though).

3) If the problem reoccurs, make sure that the steering is unlocked on the front gear only. Check each wheel, don't rely on symmetry.

4) Do a takeoff run with the view swung around to below the nose looking back. Watch the wheels; check to see if they wobble, and if so, which one first. Check if it's consistent; landing gear problems are often intermittent. Look for flexing in the surfaces which the gear are mounted to. Reinforce or relocate wobbly bits.

5) If it veers without wheel wobble, do another run and watch the aero surfaces to see if they're doing anything weird.

6) If nothing else works, pull the entire aircraft into component bits and make sure that angle snap is on when you rebuild it.

I've done 1-5, nothing fixed it. But I just realized, the radial engine bodies clip through the cargo bay. I remember you said in a guide that cargo clipping through the bay can cause odd problems, so I replaced the radials with engine nacelles facing outwards. It no longer pulls so hard on the runway! There's still a little drift, but it's random & the same as most of my planes and it's easy to get off the ground using Capslock fine controls to hold course.

One problem remains, though: When I get off the runway, I have to pull up very hard to get off the runway before running out. Even with fine controls on, when I pull up, the nose shoots up, then falls again. It's hard to settle into a steady climb, with or w/o SAS (tweaked). Could just be a change in CoM/CoL from swapping the nacelles, I'll have to fiddle later.

Thanks for your help!

[Wanderfound]

A spaceplane Munlanding demo:

- - - Updated - - -

Hey Wanderfound!

So I took your Alkahest SP4 on a mission to Minmus, to deliver a ScanSat and some crew to my orbital station. I thought you might enjoy a look.

Great plane! I like it a lot. Thanks!

http://imgur.com/a/brKPi

Cool.

Gonna take it down for a landing on the ice flats?

[WhiteKnuckle]

Ya know, it's pretty freaking cool how much you can learn just by looking at or flying something that someone else built.

I had intended to take Wanderfound's Kerbodyne VTOL Trainer for a spin, then do a review and comparison of it Vs. my Hummingbird T1. After all, they use the same engine combination, they have almost exactly the same weight, and they're built to do the same thing. I figured it'd be a pretty even matchup.

I was wrong.

It wasn't a fair comparison, not even close. I was blown away by how good Wanderfound's ship was, and although there might be one or two little things I'd change on it, it caused me to do a complete redesign on the Hummingbird because I couldn't in good conscience have it available for download on the same forum.

So, here are my thoughts on the Kerbodyne VTOL Trainer:

First off, I was amazed at how spartan this thing is, it's only got 27 parts. 27! And if you wanted to you could probably do away with the vertical rocket engines and shave off another 4 parts and a ton of oxidizer fuel. But yeah, crappy computers have no fear.

I rearranged the action groups so they fit what I was used to, just to avoid hitting the wrong button out of habit, but they're well laid out.

In VTOL mode, she lifts off evenly and doesn't do anything funky. In level flight with the VTOL engine off and the bay closed she is very fast. This is a double edged sword though, after a minute of acceleration you're going fast enough to rip the wings off with a heavy handed maneuver.

But who cares about all that, what this thing excels at, and what you'll spend all your time doing with it, is flying around KSC like a complete nut. Due to being longer, wider, and having one less reaction wheel than the Hummingbird I was worried it wouldn't be as snappy. But it's fine. Better than fine really. She's a joy to do stupid things with. It may not change direction as fast as some things, but she's supper stable even when doing her best to defy physics. I particularly enjoyed standing her on her tail 10m off the deck and moving around by rolling the body to point the VTOL engine. Really it's comfortable doing just about anything you ask of it.

The short and sweet of it is, if you want to try out a VTOL for the first time, or just want to laugh yourself silly: Download this.

The only thing I feel that this craft is missing is an ejector seat. I know I know, if you're reverting it doesn't matter a damn bit if you kill a pilot, but you will inevitably crash playing around with things like this, and to me part of the fun is somehow saving a doomed Kerbal pilot from a stunning crash. To me it's worth adding 4-6 parts and a little bit of weight.

That's it. That's my only complaint. I won't bore everyone with the design cues I stole... er... borrowed from this to help fix my VTOL trainer, I'll just say you should fly this one. Thanks Wanderfound!

[Wanderfound]

A demo with the VTOL Trainer:

[Wanderfound]

I've done 1-5, nothing fixed it. But I just realized, the radial engine bodies clip through the cargo bay. I remember you said in a guide that cargo clipping through the bay can cause odd problems, so I replaced the radials with engine nacelles facing outwards. It no longer pulls so hard on the runway! There's still a little drift, but it's random & the same as most of my planes and it's easy to get off the ground using Capslock fine controls to hold course.

One problem remains, though: When I get off the runway, I have to pull up very hard to get off the runway before running out. Even with fine controls on, when I pull up, the nose shoots up, then falls again. It's hard to settle into a steady climb, with or w/o SAS (tweaked). Could just be a change in CoM/CoL from swapping the nacelles, I'll have to fiddle later.

Thanks for your help!

No idea what's going on with the nacelles. The main cargo bay clipping problem is if the cargo is clipped through the walls: if it is, the ship will explode into a hundred pieces when the cargo undocks.

The Initiale was deliberately built with underpowered control surfaces to make it difficult to flip out of control. This means that it requires a bit more stick to lift off than most, and sometimes needs to be held at full stick (mostly at high altitude) rather than letting SAS hold pitch for you. Powering up the control surfaces will fix this, but also make it easier to lose control through rough piloting.

Most ships will surge a bit when suddenly held at full stick, especially at low speed / low altitude. Sometimes you can just push through the surge and the plane will stabilise on a steep curve up; sometimes you need to moderate your control input (if flying keyboard, tap the keys, don't hold them) to avoid surging in the first place. A quick surge at take off is normal and nothing to worry about, but after that you want to quickly settle into the desired climb angle.

If it's surging/wobbling without control inputs, you need to fix your PID settings.

[Wanderfound]

Finally managed to put a VTOL on a helipad!

Kinda...

[Wanderfound]

Kerbodyne Karnifex. Size ain't everything.

Flight test at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Karnifex/story

Alternate format at http://s1378.photobucket.com/user/craigmotbey/slideshow/Kerbal/Beta/Kerbodyne%20Showroom/Karnifex

Craft file at https://www.dropbox.com/s/ksj6huivj26x606/Kerbodyne%20Karnifex.craft?dl=0

[Jovus]

Whoa. Wings so small. How does it lift off?

Lifting body effect on the fuselage?

[eddiew]

Spaceduck! Does it carry an egg, or is that a little fuel tank in the middle?

[eddiew]

A spaceplane Munlanding demo:

http://youtu.be/MvM7_InE2rI

Great stuff, thanks Wander

After your last answer here, I was setting about designing something capable of a munlanding last night, but tying myself up in largely-contradictory desires to have enough fuel to do the round trip, enough vtol power to land, and be big enough to carry a (modded) 2.5m cargo bay. And for some reason I wanted it to be shaped like an X wing. Didn't go brilliantly, if I'm honest Think I might be asking rather a lot out of a single spaceplane. I'll follow your example and have at it with something a little smaller, at least on a first run. I've got a dinky little probe-rover that fits in a long MK2 bay; that shall suffice for now

[Wanderfound]

Whoa. Wings so small. How does it lift off?

With ease.

While the wings are thin, they're relatively long, and the whole ship is very lightweight and low-drag. It easily reaches orbit on a tiny fuel supply.

You only need broad wings if you're lifting heavy loads or want to do high-G subsonic aerobatics.

- - - Updated - - -

Think I might be asking rather a lot out of a single spaceplane. I'll follow your example and have at it with something a little smaller, at least on a first run. I've got a dinky little probe-rover that fits in a long MK2 bay; that shall suffice for now

It's easier (and usually more fun) to go small, but you can do it big: http://forum.kerbalspaceprogram.com/threads/100849-Biome-Hopper-Challenge-%28Open-for-v0-90%21%29?p=1562196&viewfull=1#post1562196

You can also get plenty done if you can make a Munlander small enough to fit in a Mk2 bay (0.725m parts are your friend here). They don't need a lot of fuel if you use the spaceplane nukes to pull them suborbital before deploying; just don't forget to reorbit the spaceplane before switching to the lander...

- - - Updated - - -

Spaceduck! Does it carry an egg, or is that a little fuel tank in the middle?

Egg.

[Flixxbeatz]

Wow, you're making SSTOs like as if they're just that simple. Totally a pro player (according to my old definition of course)

Awesome stuff!

[eddiew]

It's easier (and usually more fun) to go small, but you can do it big: http://forum.kerbalspaceprogram.com/threads/100849-Biome-Hopper-Challenge-%28Open-for-v0-90%21%29?p=1562196&viewfull=1#post1562196

Yeah... that was probably the right way to go for a plane that had to have a 2.5m section... but I never go the right way first time

In fairness, this monstrosity got to orbit with ~1200dv left. But unfortunately with just one nuke it only had 0.11 TWR which wouldn't have landed on Mun. Twin nuke version (top right) is tail heavy and harder to fly. Still, the CoM is actually inside the cargo bay, so it genuinely might be possible to make it work with some time and planning. Except it's the ugliest thing I've ever created. I don't know what got into me with those dragonfly wings

I'll try something a bit smaller with a minirover in it. Only needs a full length MK2 bay to fit my standard proberover design, and I could probably adapt it and fit an ECS on there

And I did actually make a little Minmus Puddlejumper a few weeks ago; it had a whole B9 cargo bay to live in, but it might have squeezed into an MK2 with some care...

Edited February 6, 2015 by eddiew
added spoilers; not my thread to fill with images :)

[CrisK]

I've learned that I fly Wanderfound's planes better than he does.* I just wish that I could build planes that are as stable.

*Sorry Wander, I'm still a fan! Please keep making the videos.

Edit: The trainer passes the VTOL landing-on-the-helicopter-pads test. I had to reload a few times for the second one because the landing gear would warp through the helicopter pad and the plane would become stuck.

No flight assist mods used, but I did keep an eye on Kerbal Engineer for the vertical and horizontal speed indicators. I was not able to land perfectly aligned with the H on the second one. Dang it.

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Edited February 6, 2015 by CrisK

[Wanderfound]

I never claimed to be an ace pilot.

What's your trick to accurate VTOL landings? I can put it on the pad, but I usually have enough residual lateral speed that I roll off the edge before I can stop.

[WhiteKnuckle]

I never claimed to be an ace pilot.

What's your trick to accurate VTOL landings? I can put it on the pad, but I usually have enough residual lateral speed that I roll off the edge before I can stop.

Turn the brakes on before you land (as long as you don't have control surfaces mapped to the brake key) And just keep making adjustments to kill any horizontal movement.

Just from watching your one demo video earlier I think you go way too easy on the controls of something that sized. You set your attitude and ride it down even if it isn't perfect. That's what I do too... if I'm flying a 70 ton monster. But your little trainer? Just grab it by the scruff of the neck and make it do what you want. If it isn't going right hit the rocket engines for a sec and arrest your decent, and try again.

[CrisK]

I never claimed to be an ace pilot.

What's your trick to accurate VTOL landings? I can put it on the pad, but I usually have enough residual lateral speed that I roll off the edge before I can stop.

My trick is to fly a lot of planes in Kerbal and practice not-crashing. The next time I have a weekend off I'll record a video of how to fly VTOLs and perform fun acrobatics and then stick it on YouTube.

Really, the only way to land a VTOL in Kerbal is to take it very, very slowly. Bring your horizontal speed to as close to zero as possible while your TWR is at 1.1 or 1.2. Then lower the VTOL thrust to bring your TWR slightly below 1, or at 1 if you can't maintain a stable horizontal speed. Your vertical speed should be the -5 to -2 range. It will look like you're dropping like a rock, but that's okay. Tap shift once or twice to bring the TWR to 1.2-1.4. It will take a few seconds for the jet to gain thrust, and so you'll continue dropping even though your TWR is positive. Your vertical speed will drop (become a positive) just before you reach your target, at which point you should throttle down the VTOL. If you're a daredevil you can hit x to cut the throttle completely. This works since the craft is so light, and since the VTOLs are jets (they'll exert some thrust for a few seconds after the fuel has been cut off), but you risk the craft rolling to one side; you might lose a wing.

Turn the brakes on before you land (as long as you don't have control surfaces mapped to the brake key) And just keep making adjustments to kill any horizontal movement.

Just from watching your one demo video earlier I think you go way too easy on the controls of something that sized. You set your attitude and ride it down even if it isn't perfect. That's what I do too... if I'm flying a 70 ton monster. But your little trainer? Just grab it by the scruff of the neck and make it do what you want. If it isn't going right hit the rocket engines for a sec and arrest your decent, and try again.

Yes! This is important too: use your brakes, and use those rockets if your vertical speed is higher than -8m/s.

[WhiteKnuckle]

Hey Wanderfound, I just got a video program to actually run on my computer. If it's cool with you I'd like to do a little demo flying your trainer around doing some stupid stuff. I don't have audio recording yet so it won't be a tutorial, but I can do a couple pinpoint landings and you might get a better feel for how I fly stuff.

Also, ChrisK's advice is spot on.

[Wanderfound]

Hey Wanderfound, I just got a video program to actually run on my computer. If it's cool with you I'd like to do a little demo flying your trainer around doing some stupid stuff. I don't have audio recording yet so it won't be a tutorial, but I can do a couple pinpoint landings and you might get a better feel for how I fly stuff.

Also, ChrisK's advice is spot on.

Fine by me.

BTW, I use Open Broadcaster Software for screencaps, and VideoPad Video Editor to edit and add the voiceovers that I record on my iPhone. OBS is free, and Videopad has a free trial (and a reasonable pricetag).

[Wanderfound]

Need a seriously long range cargo spaceplane, but don't want to have to fly some Mk3 behemoth? Can't be bothered with all of that reentry and landing nonsense? Hate having to lug useless wings through vacuum?

The Kerbodyne Sabot. Staging isn't just for rockets.

Annotated flight test at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Sabot/story

Alternate format at http://s1378.photobucket.com/user/craigmotbey/slideshow/Kerbal/Beta/Kerbodyne%20Showroom/Sabot

Craft file at https://www.dropbox.com/s/20cgixkub5ljo65/Kerbodyne%20Sabot.craft?dl=0

[CrisK]

Wanderfound, Can you recommend me another Kerbodyne VTOL? What model is your favourite?