Kerbodyne SSTO Division: Omnibus Thread

[Behemoth1702]

Thank you so much!

One thing I used to struggle with and still do a tiny little bit is wing desing. What parts you can use together etc. You wing extension teached me another way of wing design, thanks!

Thank you for your help mate! I'm glad that my stuff is kind of working. I got it to orbital height but not into orbit, needed around 400 m/s dV, only had 200. Oh well.

[Wanderfound]

Work on the ascent profile; it should make orbit fairly easily if you maximise Turbojet speed and altitude before lighting the rockets.

[architeuthis]

Okay: gave it a quick once over.

The basics aren't bad, but deltas are notoriously tricky for pitch and yaw stability; having the CoM right up the back of the plane makes things difficult.

It could use a bit more lift and span, so I extended the wings a touch, repositioned things a little and gave you more pitch authority: it was severely lacking in that.

It's all good up to to 28km:

But you will get a tiny bit of yaw instability after that:

For that, either spend an hour fiddling with aero surfaces to eliminate it (moar tailfin and shifting CoM forwards is probably what's needed) or just fly through it. A bit of SAS torque or a Vernor each side of the nose would help with that.

Craft file at https://www.dropbox.com/s/8ko36si0a2wsl7g/Deltatune.craft?dl=0

It is a beautiful vehicle, but unless I'm doing something wrong it does not seem to have enough lift to get off the runway (or indeed keep from plummeting into the ocean). Does this match your experience?

[ExplorerKlatt]

It is a beautiful vehicle, but unless I'm doing something wrong it does not seem to have enough lift to get off the runway (or indeed keep from plummeting into the ocean). Does this match your experience?

Are you flying it with FAR? All the craft here are optimized for FAR/NEAR.

[architeuthis]

Are you flying it with FAR? All the craft here are optimized for FAR/NEAR.

I am flying with FAR.

[Wanderfound]

I am flying with FAR.

I didn't build or test fly that one, I just fiddled with the wings until the aero analyses came good.

On test flying, though: yes, serious issue on takeoff. The issue isn't lack of lift, it's lack of pitch authority and insufficient tail clearance. It can easily get up to speed with plenty of runway to spare, and the analyses suggest that it should fly level with minimal AoA as soon as it hits Mach 0.45 or so, but takeoff rotation is a major problem at the moment.

Working on a revised version now.

- - - Updated - - -

There is something severely weird going on with that craft; despite having plenty of wing and analyses that say it should fly easily, it has about as much lift as a brick.

Behemoth: are there some clipped parts, altered configs or other weirdnesses in there?

- - - Updated - - -

In other matters, a new airframe: the Kerbodyne Sledge. Good cargo capacity, lively atmospheric performance, serious interplanetary range.

Story at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Sledge/story

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

Craft file at https://www.dropbox.com/s/nfdwpz5g56aw6ch/Kerbodyne%20Sledge.craft?dl=0

Edited January 1, 2015 by Wanderfound

[Captain Sierra]

My suggestion for that is a little trick I discovered. Take sepatrons and place them along the lateral line of the Mk2 parts. Using the gizmos, rotate them almost vertical, then offset them inward 2 snaps, and down 1. Rig that to AG or staging and you get a rocket assisted pull-up on take off. I use it on my bigger SSTOs. THe other key to this is your rear wheels need to be far enough back to keep the engines from tailstriking. For Architeuthis' plane, 2 ought to be enough to pick the nose up to a 15 degree AoA in under 3 seconds. You MUST move the rear gear much farther back than normal. You will pick the nose up very fast with this and failure to do so will destroy your engines.

[Wanderfound]

My suggestion for that is a little trick I discovered. Take sepatrons and place them along the lateral line of the Mk2 parts. Using the gizmos, rotate them almost vertical, then offset them inward 2 snaps, and down 1. Rig that to AG or staging and you get a rocket assisted pull-up on take off. I use it on my bigger SSTOs. THe other key to this is your rear wheels need to be far enough back to keep the engines from tailstriking. For Architeuthis' plane, 2 ought to be enough to pick the nose up to a 15 degree AoA in under 3 seconds. You MUST move the rear gear much farther back than normal. You will pick the nose up very fast with this and failure to do so will destroy your engines.

Sorting out the rotation issue is simple, and in this case doesn't require that sort of extreme tactic (which does work, however). Just shift the rear gear forwards to just behind CoM, raise the gear on hardpoints for more tail clearance, and increase the max deflection on the elevators. Rotates with ease once you do that.

But even with takeoff rotation sorted, it still won't fly, although it should. There's something buggy going on; it's acting as if most of the wing doesn't exist. It'd be worthwhile to run the FAR lift visualisation during takeoff to try and work out what's going on.

[Behemoth1702]

It is a beautiful vehicle, but unless I'm doing something wrong it does not seem to have enough lift to get off the runway (or indeed keep from plummeting into the ocean). Does this match your experience?

I didn't build or test fly that one, I just fiddled with the wings until the aero analyses came good.

On test flying, though: yes, serious issue on takeoff. The issue isn't lack of lift, it's lack of pitch authority and insufficient tail clearance. It can easily get up to speed with plenty of runway to spare, and the analyses suggest that it should fly level with minimal AoA as soon as it hits Mach 0.45 or so, but takeoff rotation is a major problem at the moment.

Working on a revised version now.

- - - Updated - - -

There is something severely weird going on with that craft; despite having plenty of wing and analyses that say it should fly easily, it has about as much lift as a brick.

Behemoth: are there some clipped parts, altered configs or other weirdnesses in there?

This is my vehicle, it has serious problems which is why I asked Wonderfound for help.

The rotation at lift off was fixed by A8 advanced winglets at the front of the vehicle, it still was stable.

@Clipped parts: I have no idea really. I use "offset" a lot for up/down offsets and wing building.

Is it bad to have wings clip into eachother? Is it bad to have wings clip into other parts? Is it bad for drag calc? I am not sure on how this exactly works in FAR.

[Wanderfound]

A little clipping for wing shape shouldn't cause any trouble; you don't get increased lift from clipped wings as you would in stock, but you shouldn't lose any either. I was just wondering if there were a dozen hidden intakes or somesuch.

I've run into something vaguely similar before, related to craft files going weird when shared. Does it fly okay for you once you get the nose up?

On my install, my tweaked version rotates easily, but sinks out of the sky like a deflating balloon regardless of airspeed or AoA. It's not a matter of flying badly, it's just not flying at all apart from very brief hops. There's nothing wrong with the design; I suspect that if I rebuilt the craft from the ground up it'd work just fine.

Are you using the latest versions of FAR and Module Manager?

[Behemoth1702]

I am using the latest FAR and latest MM.

On my install your tweaked version still has big troubles pitching up at the runway and after the runway it has not enough pitch power to be able to hold itself straight. It "feels" as if the front is very heavy.

Funny enough - your file is 163 KB, when I open it, give it another name and save it again - 159 KB

Here.

http://www./download/gjcxqexu0f2ql2k

So... something funky going on.

Maybe removing and re-adding control surfaces could help.

Edited January 2, 2015 by Behemoth1702

[Wanderfound]

Just to get this sorted, I did go and rebuild it from the ground up (with a few tweaks). Since you mentioned canards, I added some on; they aren't strictly necessary, but it does improve lateral stability a touch as well as avoiding the need to supercharge the rearset elevators/elevons.

Craft file at https://www.dropbox.com/s/kw9ifx4fumn6zwc/Deltatune%202.craft?dl=0

All nice on the analyses:

Rotates easily at moderate speed:

Flies smooth with minimal AoA once it's in the air:

Do be careful of excessive (>5) low altitude G's, though; the wing strength is enough for sensible flying, but not for major sillyness.

But it's got no problem with steep climbing and moderate G's if flown appropriately:

All smooth under time acceleration (do not try this at treetop height):

Four jets until the air runs thin:

Then two jets to extend the flight ceiling:

Before kicking in the rocketry around 30,000m:

Once the air supply runs low enough that asymmetric thrust becomes a danger, kill the turbos, shut the intakes and lift the nose:

Comfortably to orbit with fuel to spare:

Edited January 2, 2015 by Wanderfound

[Hodo]

Thank you so much!

One thing I used to struggle with and still do a tiny little bit is wing desing. What parts you can use together etc. You wing extension teached me another way of wing design, thanks!

Thank you for your help mate! I'm glad that my stuff is kind of working. I got it to orbital height but not into orbit, needed around 400 m/s dV, only had 200. Oh well.

Climb to about 12-16km and bring your AoA down to about 10-15deg and accelerate as well as you can. Once you get up to about 25km you should be going around Mach 4+ if you can push to mach 4.5 you are doing great. Then kick your rocket in at that point and turn off your turbojets, then pitch up to 20-25deg. You should reach orbit pretty easy after that.

[Behemoth1702]

Just to get this sorted, I did go and rebuild it from the ground up (with a few tweaks). Since you mentioned canards, I added some on; they aren't strictly necessary, but it does improve lateral stability a touch as well as avoiding the need to supercharge the rearset elevators/elevons.

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot428_zpse5263861.jpg

Craft file at https://www.dropbox.com/s/kw9ifx4fumn6zwc/Deltatune%202.craft?dl=0

All nice on the analyses:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot427_zpse2dd458f.jpg

Rotates easily at moderate speed:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot430_zpsa9239be7.jpg

Flies smooth with minimal AoA once it's in the air:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot431_zps978903f1.jpg

Do be careful of excessive (>5) low altitude G's, though; the wing strength is enough for sensible flying, but not for major sillyness.

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot432_zps6f058526.jpg

But it's got no problem with steep climbing and moderate G's if flown appropriately:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot434_zps315abc7b.jpg

All smooth under time acceleration (do not try this at treetop height):

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot435_zpsd3260d14.jpg

Four jets until the air runs thin:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot437_zps2fedca03.jpg

Then two jets to extend the flight ceiling:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot438_zps8b67f96d.jpg

Before kicking in the rocketry around 30,000m:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot439_zps8c531be6.jpg

Once the air supply runs low enough that asymmetric thrust becomes a danger, kill the turbos, shut the intakes and lift the nose:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot440_zps28666831.jpg

Comfortably to orbit with fuel to spare:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Deltatune/screenshot442_zpsc34db3c3.jpg

Wow, thanks man for taking it so seriously! I see you added bigger wing connectors between the lateral and central tanks, maybe that extra lift helps?

Climb to about 12-16km and bring your AoA down to about 10-15deg and accelerate as well as you can. Once you get up to about 25km you should be going around Mach 4+ if you can push to mach 4.5 you are doing great. Then kick your rocket in at that point and turn off your turbojets, then pitch up to 20-25deg. You should reach orbit pretty easy after that.

I usually lack the air intakes to make it much further above 25 with around mach 3.8 or something. I have not found the "borders" yet. Altitude/max speed at it/enough air intake are tough to figure out.

What is more important during final ascent at let's say mach 4/25km altitude? To gain more speed OR to climb steeper? What pitch angles do you use?

[Wanderfound]

Wow, thanks man for taking it so seriously! I see you added bigger wing connectors between the lateral and central tanks, maybe that extra lift helps?

That was not actually intentional. It should work either way; it isn't at all lacking in lift. If it were, it would require a much larger AoA to maintain level flight than the 5° or so it needs at low altitude.

I usually lack the air intakes to make it much further above 25 with around mach 3.8 or something. I have not found the "borders" yet. Altitude/max speed at it/enough air intake are tough to figure out.

What is more important during final ascent at let's say mach 4/25km altitude? To gain more speed OR to climb steeper? What pitch angles do you use?

They're both important. An orbit is a speed more than it is an altitude, but, OTOH, from an aircraft perspective altitude is speed in the bank.

So long as you can continue to gain speed without rockets, keep the nose down and the climb rate low. Try to avoid losing altitude, but don't panic if you do; so long as you keep your nose a bit above the horizon, a dive should eventually turn back into a climb (reductions in altitude and increases in speed both reduce the AoA required for level flight; it's all about how many air molecules hit your wings in a given time).

Previously, a flat-as-possible ascent was the most effective and efficient in FAR, and Mach 5 was easy to reach on jets alone. With the improved skin friction effects introduced in the latest FAR, things have changed a bit. You still want to maximise your jet speed, but you also want to get above the drag (>50,000m) as soon as possible. And it is now much more difficult to accelerate above Mach 4 with jets alone. So, as flat as possible while maintaining a shallow jet climb, but pull the nose up as hard as you can without losing control as soon as you light the rockets.

1) Climb steeply (but not so steep that you lose airspeed and stall) up to about 15,000m. The steep climb also helps to keep your speed down in the dangerously thick lower atmosphere.

2) Flatten off and pile on as much jet speed as aircraft and pilot patience allow.

3) Try to gain as much altitude as possible, but don't pull up so hard that you start to lose significant amounts of airspeed. Shutting down surplus jets and gradually throttling down can increase your flight ceiling substantially. I've only just lit the rockets in the picture below; you can see the altitude increase over the previous pic, as well as the fact that I'm slightly throttled down.

4) Pull the nose up hard after lighting the fireworks.

Edited January 3, 2015 by Wanderfound

[Behemoth1702]

Thanks for the tips!

I can get my Mk2 SSTO to 75km altitude now, unfortunately only with like 400dV left, just enough to circulize and de-orbit. Have to have a good re-entry or I'll end up landing somewhere else, hehe.

Oh boy. Now that I get stuff flying I need to figure out how to get the most FUEL flying, since I want to re-fuel my orange tank fuel station (inspired by your kerbodyne tank fuel station).

I dont have RAPIERs unlocked yet to save that weight. And also I only have "basic" action groups, so no "1-9" for me. I use "abort" to shut off jets and close intakes.

On a side note - these "engine body" style air intakes produce a .... TON of drag on my install, this has been brought up in the FAR thread as well a few pages back. Do you have the same experience?

Thanks for all the help man.

Oh btw - happy new years.

EDIT: Just made it into orbit with 1000 dV left! Had a good ascent profile, got to Mach 3.6 at 26km, could not get higher/faster, accelleration was waay to slow and I had to reduce thrust to save air. So I fired up the rocket, ramFed the intakes until it made no more sense, pulled as high as I could (pilot assistant SSAS does wonders for me) and there we go! 400m/s to circulazie and tadaa - even docked to my refuel-tank, left around 300 fuel there, had like 50 left. De orbit burn and then, without any fuel using the last monoprop I managed to glide into the KSC.

Thaaaaank you!

Edited January 3, 2015 by Behemoth1702

[Wanderfound]

Even Kerbodynye pilots occasionally find themselves in too much of a hurry to fly to orbit properly. Or you could find yourself a bit cash-strapped and need a budget launcher to raise the money for a real spaceplane. We've got you covered.

Kerbodyne Satshot: take the express elevator.

Annotated demonstration at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Satshot/story

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

Craft file unnecessary; it's only 18 parts.

[Wanderfound]

Got a good one.

Your ultimate science gathering suborbital hopping VTOL exploring survey completing fun machine: the Kerbodyne Dragonfly.

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

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

Craft file at https://www.dropbox.com/s/7qkdwzegoghay6k/Kerbodyne%20Dragonfly.craft?dl=0

[Wanderfound]

New! Improved! And absolutely freaking mindblowing!

Kerbodyne Dragonfly X

Annotated flight demonstration at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Dragonfly%20X/story

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

Craft file at https://www.dropbox.com/s/5iwb5g9kn56nl5g/Kerbodyne%20Dragonfly%20X.craft?dl=0

Edited January 7, 2015 by Wanderfound

[Wanderfound]

Developing the theme...

Kerbodyne Skyfang.

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

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

Craft file at https://www.dropbox.com/s/xvv4zsla1y9pg5s/Kerbodyne%20Skyfang.craft?dl=0

[Wanderfound]

And another one...

Kerbodyne Skyfang XN.

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

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

Craft file at https://www.dropbox.com/s/i4pocky5rwu6xyf/Kerbodyne%20Skyfang%20XN.craft?dl=0

[Gaalidas]

New! Improved! And absolutely freaking mindblowing!

Kerbodyne Dragonfly X

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Dragonfly%20X/screenshot545_zps036e4c01.jpg

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Dragonfly%20X/screenshot566_zps47a9269a.jpg

Annotated flight demonstration at http://s1378.photobucket.com/user/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Dragonfly%20X/story

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

Craft file at http://s1378.photobucket.com/user/craigmotbey/slideshow/Kerbal/Beta/Kerbodyne%20Showroom/Dragonfly%20X

Technically, that craft file link is a photobucket album... might want to check that one.

[Wanderfound]

Technically, that craft file link is a photobucket album... might want to check that one.

Whoops, thanks.

[Wanderfound]

I appear to be on a roll; this one was awesome fun to fly.

Kerbodyne Aero R. The space-going sportster for tomorrow's best pilot.

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

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

Craft file at https://www.dropbox.com/s/mdo73c4wovjjt68/Kerbodyne%20Aero%20R.craft?dl=0

Edited January 7, 2015 by Wanderfound

[eddiew]

Lol, just as I was wondering about trying some forward-swept designs I like the little Aero R - stick a 1.25m probe core in there and it could do for those orbital rescue missions. *edit* It's got one and I didn't notice

Not sure about the control surfaces on the front of the dragonflies though... in my brain, the airflow would rip them off and/or flip the plane xD

Edited January 8, 2015 by eddiew