The Art of landing.

[Mikki]

Thanks! Yes, how do you get the 5 m/s sinkrate to converge with the beginning of the runway?...

Ahh, i... i am aiming at beginning of the runway, never assume to match it..., as you see in the pic, i am very carefull with my Kerbals...

I am really interested in your X-15 design plane... makes me curious if there is a way to land such big thing, it must be done somehow!

I think some Kerbal Engineers have found some work and must investigate this idea...

Greetings Mikki

[martinborgen]

If you do not mind a little actual constructive criticism, might I recommend you replace the rocket engine? You are using a Mammoth, which is unmatched in power as a heavy lifting engine, great for when you need to accelerate a lot of mass off the surface. Unfortunately, it is also very heavy and very fuel-hungry, and by the time a spaceplane needs its rockets it is already going supersonic and rising out of the thickest of the atmosphere, which means that the Mammoth is rarely an efficient spaceplane engine. If you swap it out with something else, you can reduce both the mass of the engine as well as the mass of the fuel it requires. That reduction in mass, though not a pancea, will make the design a bit easier to take off and land because less mass means you require less lift to stay airborn.

The easiest swap to make would be to use the Rhino engine as a replacement, since it is the same diameter. It does not have the Mammoth's immense thrust, but its thrust is still substantial by the standards of a single engine and it has one of the better fuel efficiency ratings, especially at the level of thrust it outputs. Alternatively, you could use an appropriate adapter part and quad coupler to place a cluster of smaller engines on the back. Aerospike engines are traditional for spaceplanes, and offer a good balance of thrust and efficiency, though LV-45 engines also work well in that role. Might be worth taking a fuel tank out of the fuselage while you are at it, shortening the splaceplane a bit if you replace the engine, since you will need less of it and carrying more than you need runs into diminishing returns, especially where spaceplanes are concerned.

By all means, that would be a more traditional space plane approach (I have a few of those designs that work quite satisfactory). I just don't like using 30-something rapiers or so, because of the bloated part count (lower FPS). This rocket doesen't use the jets for more than a little boost and to calibrate landing - most of the thrust is from the mammoth, all the way from the runway. The launch is also much faster that way. (originally designed to launch from pad, but rolling start gave the jets twice the thrust, and a lot more payload to orbit).

However, the deign is secondary to the topic (just to be clear, this is an alternative design experiment from me, not the way I try to build all my spaceplanes) - the actual topic is the landing procedures, to see what tips and tricks people use to make landings easier, in what is not really a flight-friendly game UI. I do appreciate the construction tips about wing Angle of Incidence, and such. Having this hard-to fly experiment is what made me think of the very details of landing in KSP. Generally, I land without too much trouble in my more conventional designs.

Speaking of which - has anyone fond a nice usage of the deploy function on control surfaces?

[A_name]

And funnily enough, it doesn't use Nervas and "Swivel" engines instead.

Oh you're right, my eyes played a trick on me there!

- - - Updated - - -

Speaking of which - has anyone fond a nice usage of the deploy function on control surfaces?

I heard they could be used as makeshift air brakes (kind of like the Space Shuttle would use it's tail rudders) but I've never tried.

[Val]

...

I do appreciate the construction tips about wing Angle of Incidence, and such. Having this hard-to fly experiment is what made me think of the very details of landing in KSP. Generally, I land without too much trouble in my more conventional designs.

...

I hope that advice proves useful.

In case it wasn't clear, that post was meant as encouragement, by showing that it is indeed possible to design very long spaceplanes like yours, that are benign to land, even with limited amount of wing area.

...

Speaking of which - has anyone found a nice usage of the deploy function on control surfaces?

The spaceplane in my post does have the Deploy function of the elevons mapped to the Brake Action Group.

[martinborgen]

Yes, I found your post very nice, always enlightening to see others' take on the problem.

I can now proudly announce that I've managed to get a configuration for this plane that works. I added the S-control surfaces and canard to my delta wing (and moved the yaw rudders so they won't induce roll). The S-control surfaces added quite some lift. Also a Shift-tap incidence on the wing and forward control surface. Mapped the S-control surfaces to action group, deploy as if maximum elevation, and two aerospikes in the cargo bay as retro thrusters.

The S-control surfaces on action group turned out to be both flaps, brakes and flare control - activating this on the last few hundred meters gives me a nice flare in at ~150 m/s, some engine to control descent, and upon ground contact, press action group that shuts down all engines, opens cargo bay, fires aerospikes, turn on brakes and deploy drouge chutes. Extra pair of radial chutes as needed, though not above 100 m/s or craft brakes apart.

[Pecan]

Congratulations

[Wjolcz]

Nice. Now I feel kinda bad for discouraging you. Good to see you figured it out.

[A_name]

Nice!

[Vegetal]

Sorry, didn't want to not be constructive. The design looked really funny to me.

As for parachutes, I've had no problem using them to slow down my planes on the runway, it's probably a good idea if your landing speed is so absurd. One thing to note with that final design, the cargo bay in the front tends to create a lot of drag with big angles of attack, and that can be problematic when trying to maneuver.

[Fearless Son]

However, the deign is secondary to the topic (just to be clear, this is an alternative design experiment from me, not the way I try to build all my spaceplanes) - the actual topic is the landing procedures, to see what tips and tricks people use to make landings easier, in what is not really a flight-friendly game UI.

Ah, I gotcha'. My thought process was something like "Reduced weight leads to increased relative lift, increased relative lift leads to lower minimum sustainable airspeeds, lower minimum sustainable airspeeds lead to easier landings."

Trying to think of ways of making the landing more effective without adding additional lifting surfaces that might increase your drag and ruin the aesthetic you look like you are aiming for.

[Captain H@dock]

Thank you for your constructive criticism. Perhaps you need help distinguish between the act of taking off and landing - we're discussing the latter. The X-15 did land by itself, in case you didn't know.

While you're correct, have you looked up X15 landing video? I just did, and it is pretty scary! I wouldn't want to be regularly operating a space plane with such a tight landing envelope...

I've tried landing several low lift craft in 1.0.4 with a joystick, and they aren't nice to perform. You usually need in excess of 150 m/s on final, and a perfectly timed flare!

My regular small and medium SSTO are touching down between 40 and 60 m/s (on a glide from orbit). That means I have a lot of margin for error during approach and final, which means 100% landing success.

So I think with some training you can land this, but it will always be a challenge. Which obviously should not prevent you from operating it. This is KSP.

EDIT:

However, the deign is secondary to the topic (just to be clear, this is an alternative design experiment from me, not the way I try to build all my spaceplanes) - the actual topic is the landing procedures, to see what tips and tricks people use to make landings easier, in what is not really a flight-friendly game UI. I do appreciate the construction tips about wing Angle of Incidence, and such. Having this hard-to fly experiment is what made me think of the very details of landing in KSP. Generally, I land without too much trouble in my more conventional designs.

Like you said. Powered landing, on the back of the drag curve. It find it quite tricky to do in KSP, compared to 'real planes', and obviously the spool-up time of the jet is not your friend for that. Also, cockpit IVA for an accurate VSI reading.

Speaking of which - has anyone fond a nice usage of the deploy function on control surfaces?

Yes, flaps. This can help with landing/take-off speeds, but I don't think it would work on your design (you don't want your flaps to induce pitch, so you would need them in pair centered around the CoG). Also, my feeling is that it hurts drag, so I don't include it in my SSTO. But I could post a proof of concept if you want. Edited August 12, 2015 by Captain H@dock

[martinborgen]

While you're correct, have you looked up X15 landing video? I just did, and it is pretty scary! I wouldn't want to be regularly operating a space plane with such a tight landing envelope...

http://youtu.be/OFmfFMoUQZQ

I've tried landing several low lift craft in 1.0.4 with a joystick, and they aren't nice to perform. You usually need in excess of 150 m/s on final, and a perfectly timed flare!

My regular small and medium SSTO are touching down between 40 and 60 m/s (on a glide from orbit). That means I have a lot of margin for error during approach and final, which means 100% landing success.

So I think with some training you can land this, but it will always be a challenge. Which obviously should not prevent you from operating it. This is KSP.

EDIT:

Like you said. Powered landing, on the back of the drag curve. It find it quite tricky to do in KSP, compared to 'real planes', and obviously the spool-up time of the jet is not your friend for that. Also, cockpit IVA for an accurate VSI reading.

Yes, flaps. This can help with landing/take-off speeds, but I don't think it would work on your design (you don't want your flaps to induce pitch, so you would need them in pair centered around the CoG). Also, my feeling is that it hurts drag, so I don't include it in my SSTO. But I could post a proof of concept if you want.

The X-15 is pretty scary, but pretty cool. The trick is maintaining the AoA. Which leads me to what you wrote about flaps. I have now successfully landed several times using flaps that induce a strong upwards pitch - as I need to maintain high AoA at low speeds. Basically, the flap-thing (extra lift at low speeds) is provided by the fuselage.

[BlueCanary]

My way of landing is to plant a flag at the end of the runway (the end you want to land at), set it as target, and hold the prograde marker of the navball over it until you're low enough to flare. This is also good for judging alignment and glideslope, I find 5-10 degrees glideslope usually works well, although 3 degrees is more realistic.

[match]

Re: high AoA requirement for landing

Have you tried placing. Vernor engines on top of your elevators? These can aid attaining desired AoA and be shut off for the remainder of flight.

[Captain H@dock]

The X-15 is pretty scary, but pretty cool. The trick is maintaining the AoA. Which leads me to what you wrote about flaps. I have now successfully landed several times using flaps that induce a strong upwards pitch - as I need to maintain high AoA at low speeds. Basically, the flap-thing (extra lift at low speeds) is provided by the fuselage.

Regarding flaps: You need to position your flaps in-line to the CoG (along the longitudinal axis), or event better, match it with a slat (slat on the leading edge of the wing, moving up, flap at the trailing edge, moving down). I'll post pictures later.:

Regarding maintaining the AoA on airflow only: You need to do your flare just at the right time, because the speed will decay quick enough that you don't get a second chance... A very accurate Radar altimeter and VSI does help for that, but we only have the later in the IVA view.

[A_name]

Re: high AoA requirement for landing

Have you tried placing. Vernor engines on top of your elevators? These can aid attaining desired AoA and be shut off for the remainder of flight.

Could you elaborate on how this would work?

[Nich]

Asymmetric wings are really nice for long craft like this

Looks like you have already added flaps and ailerons to the main wing. I never let the tail control roll it does some wonky stuff IMO

I would still go with a Rhino

How much payload are you delivering?

[martinborgen]

Asymmetric wings are really nice for long craft like this

Looks like you have already added flaps and ailerons to the main wing. I never let the tail control roll it does some wonky stuff IMO

I would still go with a Rhino

How much payload are you delivering?

How do you mean asymetric?

Yes, roll is one of the main wing only. Perhaps a Rhino would do better if I tweaked the fuel load - I tried and it worked but I had much smaller margins.

Basic criteria is one orange tank module (an orange tank plus some docking ports, rcs and panels). So say 38 tons at minimum. The Mammoth-engined verision can probably take more than 40 tons.

Starting weight is about 380 to 400 tons, so it's not an efficient SSTO (10% payload compared to 25-30%?), since it doesen't use airbreathers to maximum gain - but then it's a much simpler craft - keeps the part count much lower which is nice. Now I recently figured out a setting on this laptop that limited my performance, so the craft has lost some of it's original purpose. Still, it's a rocket-speed lauch, which is nice.

[match]

Could you elaborate on how this would work?

Well, on approach flaps increase lift and drag which is good for lowering stall speed. Some planes need a bit more nose up than the flaps provide. A pair of vernors on the elevator pointing up (pushing down) can provide this via RCS. I use it with the fine tune off so it does not attempt to stabilize.

YMMV

[A_name]

Well, on approach flaps increase lift and drag which is good for lowering stall speed. Some planes need a bit more nose up than the flaps provide. A pair of vernors on the elevator pointing up (pushing down) can provide this via RCS. I use it with the fine tune off so it does not attempt to stabilize.

YMMV

Yeah I've used vernors like this before but usually under the nose and/or the COM. What I was wondering more on was the placement on the elevators, what's the purpose of putting them there exactly?

[BlueCanary]

If you're having difficulty lifting the nose enough, try and get the CoM and the CoL closer together to reduce lawn-dart-ism, or add more control surface area far from the CoM. Depending on the craft's weight and speed I find this can have quite a bit more effect than vernors.

[match]

Yeah I've used vernors like this before but usually under the nose and/or the COM. What I was wondering more on was the placement on the elevators, what's the purpose of putting them there exactly?

You could do either front or back, I guess. I use translation down to change the AoA so I can keep making needed changes on final apporach with the standard directional controls. Having the vernors only in the back allows an asymmetrical thrust resulting in torque instead of translation. (All that time docking with bad RCS layouts gave me the idea). Butt goes down, Nose comes up, wheels go round and round.

[Captain H@dock]

So here is my most extreme plane example regarding flaps. 131 Tonnes takeoff weight (center fuselage is half full).

3 Flap+Slat combo per wing, each with their own action group. Each couple is center around the CoG as to produce no pitch up torque, and the slat is sunk in the wing leading edge. Action group 1,2,3 for them, which gives 3 flap deployments options:

Aero display at similar speed shows the huge difference full flap makes

Take off distance and speed are vastly improved (95 against 135), but full flap max speed is 140. Also, too fast when deploying the flaps will tear the wings off...

But as I said, I don't think this could work on OP's craft as it doesn't have a wing section at the CoG...

Edited August 12, 2015 by Captain H@dock

[martinborgen]

Probably not, but that's a beautiful flap configuration!

[KerikBalm]

STOs are notorious for how little payload they can carry, if you're looking for the ability to carry a large payload to orbit you're better off with a rocket.

As others said: SSTOs aren't made for big payloads. Unless it's Rune's MK3 monstrosity.

Then that notoriety is undeserved.

I often take 120+ ton payloads to orbit that are longer than 2 orange tank lengths, and wider than 3 orange tank widths.

Link to Rune's mk3 monstrosity?

I have monstrosities of my own, mk3, and not so mk3...

In 1.04:

Previously in 1.02, same design (note how I can enclose the whole payload in a fairing if needed)

Not so monstrous.. mk2 based, but still good for payloads too wide for mk3 bays:

an earlier version(less powerful), before fairing deployment (these should work better in 1.04 with the fairing mass reduced... not sure how the drag reduction and the reduced thrust affect things... but based on my other SSTOs working just about as well in 1.04 as in 1.02 and getting similar top speeds, I imagine that they still work)

Oh the monstrosity:

1.0 monstrosity:

https://scontent-mxp1-1.xx.fbcdn.net/hphotos-xpf1/t31.0-8/s720x720/11032221_10103550674651363_2148940416804389397_o.jpg

https://scontent-mxp1-1.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/s720x720/10419418_10103550674142383_5163611685085914391_n.jpg?oh=0ba8b5ecbbfa4578ae3286a1e3741346&oe=564754A0

Can we *please* stop pretending that SSTO spaceplanes can't lift large cargos, or that only special people can get them to lift large cargos?

*please*

They should not be notorious for only being able to lift small payloads.

Lol, your "plane" is very bad man. Also, the X-15 didn't take off by itself, remember... it was also quite small.

I for one think it looks pretty bad4$$.

Sure... it doesn't look very practical... but it looks very "kerbal"

Lots of thrust, love the RATOs to lift up the nose... very low drag coefficient...

I like it and give it many coolness points.

I share the OPs disdain for high part counts... but its a disdain I accept... my large SSTOs make my game run pretty slow. I also added RATO boosters just to get them off the runway faster (making them no longer a true SSTO, even though they are more than capable of SSTOing... it just saves play time)

While you're correct, have you looked up X15 landing video? I just did, and it is pretty scary! I wouldn't want to be regularly operating a space plane with such a tight landing envelope...

Doesn't look so bad to me.

Edited August 14, 2015 by KerikBalm