How to land an airplane?

[arien101]

I've been playing with rockets so far. Landed on the Mün and Minmus, docked and rendezvous'd, but am only now trying airplanes. Found the post below on airplane design which has been incredibly helpful, but I struggle with landing.

http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures

I haven't played a flight sim in forever and don't have a joystick (not sure if that matters). I'm using precision controls and SAS to fly. Lifting off and flying works. No problem. The tips above have helped me build an airplane that handles ok. Yet I always fail horribly at landing the thing. Have tried 10+ times and it seems I always come in too fast. Plane bounces back up and then is out of kilter, loses a wing and then crashes.

try to reduce my speed to below 100 m/s, but I seem to be dropping too quickly. I've watched a couple of tutorial videos, but somehow am not getting the hang of it. Any pointers on what I might be missing?

Thanks!

Edited June 18, 2015 by arien101

[Empiro]

Patience and a soft touch is the key. Don't turn too fast or make any aggressive maneuvers. I usually like to disable SAS and rely on precision controls and the trim settings to control my glide slope.

100 m/s is completely landable, but you can definitely go slower, assuming that your craft doesn't have tiny wings for its size. Just pull up more (or use trim settings) to increase your angle of attack and slow your descent. You want to be descending less than 5 m/s to avoid bouncing. Just before you touch down, you may also want to pull up slightly to flare. This slows your descent further, and also quickly slows you down.

Above all -- practice. Save the game when you're a few KM from the runway. If you crash, reload and try again. You'll get the hang of it soon enough.

[FancyMouse]

Watch your vertical velocity. If you have mods like KER - keep close eye on that when landing. As long as vertical velocity is as slow as like 5m/s, your landing gear brake will take care of 100m/s horizontal velocity. This usually means anything >15 degree when approaching the runway is going to give you some trouble, which I guess might be your problem.

[Chaia]

Just one word: Parachutes ;-)

[diomedea]

Hi arien101,

some of the points that help me with landing.

1. About dropping too quickly: does your plane have enough lift at low speed? it may not have wings large enough to provide lift at the final approach speed (please note, it is easier to take off with small wings than to land, because during T/O you use full thrust oriented by the angle of attack).

2. Find what the minimum safe speed is with your plane at very low altitude. Just fly straight, low and slow, and see when you can keep altitude from dropping further. Any slower will bring your plane to stall. That speed is the absolute minimum you must never go below during approach. Also, take note of the angle of attack when you can keep altitude at the minimum speed.

3. It is possible to fly with just a keyboard, but exercise with the throttle control (shift, ctrl). During approach the angle of attack is generally kept fixed, and rate of descent is a function of thrust, so you have to be able to change thrust fast enough to correct.

4. SAS may actually fight against a plane natural attitude, and induce oscillations or worse. With a plane built to be stable there is no need to use SAS (e.g., center of lift above the center of mass and positive dihedral angle help to keep roll neutral). Could be better to exercise flying without SAS.

5. Choose a correct glideslope for your craft. Most aircrafts do with 2.5 - 5°. It should allow your craft to descend without changing speed, while keeping vertical speed under control.

6. With all the above set (airspeed, angle of attack, glideslope, correct amount of thrust), you start aligned with the runway aiming for the gate. Correct thrust when lowering gear (due to increased drag). Just before the gate start a flare (increase angle of attack and cut thrust), it will increase lift so reducing the rate of descent, while also depleting airspeed. With proper timing and amount the flare will make for a gently touchdown, and that is needed to avoid bumping back in air. Immediately apply brakes and level (angle of attack down to 0).

and sorry in case you already knew most of the above , but some points could turn useful for others too.

[Dilli]

Set the brakes for the front of the craft low (5 of 30 or so) and max the ones at the back, it will help with stability on braking. It can help to only start applying the brakes once all wheels are on the ground.

Keep a bit of throttle on the engines to avoid stalling onto the runway and help with control (trust vectoring), just before or once the back wheels are on the runway cut throttle. The aim is to fly onto the runway gently (with the nose slightly up if you can) - As mentioned above it is your vertical speed that is key to successfully landing.

Edited June 18, 2015 by Dilli

[BlueCanary]

Try placing a flag at the end of the runway, setting it as target and holding the surface prograde vector over it. This really helps with judging glideslope from the third person, kind of fisheye-ey view ksp has. Also, watch the shadow to judge height over terrain and, at least on small planes, you can try and hold off a couple of metres above the runway for as long as you can until speed drops low enough that it just floats down. Big craft might run out of runway though.

For vertical speed the surface prograde marker on the navball is probably more useful than the vertical speed gauge, since it's nearer to the speed indicator and isn't logarithmic so it's easier to read.

Or, try using something with lots of wings and drag as a trainer to get experience with landings before you try anything fast and heavy or without much wing. The stock Aeris 3a is quite good for this, it's maneuverable and slowish so it's nice and forgiving.

Also, don't rush, especially with big, heavy or fast planes. Take time to set up an approach from far enough back you have plenty of time to kill speed and make corrections, and if things are getting messed up don't overcorrect and crash, go around for another approach.

For runway alignment I find sideslipping works best for small corrections.

As diomedea says, what's the wing loading on your plane? As in, how much wing area does it have compared to mass?

As for design landing will be easier with lots of low speed control authority - so lots of control surfaces, and wide set undercarriage that points straight down so it doesn't roll and crash after touchdown.

Edited June 18, 2015 by BlueCanary

[Sharpy]

A drogue chute on the tail end goes a long way.

[Juicy]

Try placing a flag at the end of the runway

Or better even, set a flag at both ends of the runway, so you have two dots to line up for a perfect approach! It beats eyeballing the runway by a long stretch!

[Warzouz]

As I understand your problem is the final approach of the landing strip.

- You can practice landing on KSC ground instead of the runaway. It's flat and safe.

- Despite others had said, I wouldn't deactivate SAS as it help a lot keeping your plane straight.

- Press CTRL to trun you control to fine tune. It helps steering slowly.

- All planes aren't as easy as other to land. Preactive ith a simple plane first. For instance, spaceplane are harder to land, they usually have less wing surface.

- If you plane turns too harshly, remove some of your control surface (especially for roll).

- Airbrakes helps a lot on landing in the final few meters. Simply open them near the strip. You can then dive to the strip and you only have to nose up at the last minute. As you speed will be low, you won't be able to rise, but this will slow your descent.

- - - Updated - - -

Or better even, set a flag at both ends of the runway, so you have two dots to line up for a perfect approach! It beats eyeballing the runway by a long stretch!

Other advantage : use the front flag as TARGET.

[Mic_n]

The general idea is to be "almost stalling".

It really depends on the individual craft, though... but in a nutshell, you want to be very slightly nose up and with just a little bit of thrust to keep you pushing along. You need to almost think about it as a completely different way of flying, and when you're in that sort of attitude, you work your elevator and throttle controls around the other way: if you want to go faster, push your nose down a little.. if you're falling too fast, give it a little more throttle. You should be able to just about stall it in.

Practice makes perfect.

kinda like this:

[ajburges]

Landing is a balance of several things. Here are just a few of my observations.

Approach: a good approach makes touch down easier. You want to line your flight up within 5° degrees of the runway (less is better) and tune speed for level flight (maybe a little less). The idea is to get closer to touchdown conditions so you don't need as much correction when you want to land. Runway flags can help with alignment and establishing a glide slope.

Final approach: you have good perspective on the runway. Align your approach. Remember you change heading with roll and pitch, not yaw. Check that gear and flaps are deployed.

Point of no return: this is where you make the decision to abort or land. If you are too high or not aligned with the runway, abort! Don't attempt to land. Large corrections before landing is a recipe for disaster. Control surfaces are to control attitude and lift from here out. Use yaw to align heading with velocity, keep wings level, and use pitch for decent control.

Landing: right before touchdown, flare the craft, use airbrakes, and/or pop landing chutes. You can easily handle 120 m/s on touchdown, but less than 80 is more sane. You want less than 10 m/s vertical velocity on the gear. Gear can typically handle rougher landings than your airframe can. Get in the practice of level touchdown. Landing torque can create surprising force and tail strikes are misfortuneate. Once you touch down, use yaw only to correct heading to stay on runway steering with wheels at high speed is a recipe to tip.

All my craft to date can stop in less than ¼ a runway. This gives you more flexibility in your point-of-no-return. The more flexible/later you make that point the easier your landings. Landing a powered glider that can maintain stable flight at 60 m/s is trivial. Landing a space plane that needs 140 m/s for level flight requires some thought. Landing a glider with a 160 m/s glide slope is tricky.

Edited June 19, 2015 by ajburges

[arien101]

Thanks for the great responses. Between all these tips I managed my first landing :-)

I didn't have to change the design. Main tips that helped me was the flags for alignment and more closely watching vertical velocity. Funny thing is after reading all of the tips I managed the landing on the next try :-)

Thanks!

[Falkenherz]

Approach very low so you do not need a lot of course corrections on the last meters. This way, you basically just glide on the runway with about -10m/s.

[SAI Peregrinus]

http://forum.kerbalspaceprogram.com/threads/85353

That's probably the most useful mod for landing if you've played any other flight sim, or otherwise know how to use a HSI.

[carlorizzante]

[...] Also, watch the shadow to judge height over terrain and, at least on small planes, you can try and hold off a couple of metres above the runway for as long as you can until speed drops low enough that it just floats down. Big craft might run out of runway though. [...]

Actually, it would be sweet to have a landing runaway, 90 degree with the take-off runaway we already have. So that the shadow would be at the side, and not behind the aircraft.

[moogoob]

I find using flaps helps with some designs, but the biggest issues I have in landing are A) getting speed low enough while still flying and getting my approach to be properly aligned to the runway and not either falling short or missing half the runway. I'm getting better though! My advice is to just practice. Try airbrakes, and flaps, and see what works best for you.

[Paulie]

I havent seen any flaps in the game yet, are they a new part high in the tech tree?

Dont see them on KSP wiki either.

And how would you raise them?

[Warzouz]

Use AIRBRAKES ! That's too easy

You can land by diving on the runway and just nose up a little. The airbrakes will kep you speed low and you won't crash. I did a looping landing with my 37T spaceplane (and 4 airbrakes) which is not the easiest plane to fly... Takeoff, start looping until you're on your back. Fly over the runway backward. On the end of the runway, cut engines, open airbrakes, finish looping and dive to the runway. Nose up just before landing.

This is a good training though... You can even do it multiple times.

[Dilli]

I havent seen any flaps in the game yet, are they a new part high in the tech tree?

Dont see them on KSP wiki either.

And how would you raise them?

IIRC any control surface can now have its state toggled via action groups (ie deployed and normal)