Airplane doesnt fly well

[Jetsim]

http://tinypic.com/view.php?pic=214carn&s=8#.U8_QRPl_tK8

My first airplane, problems are: Doesnt take off until runway ends and even then it doesnt fly much and flying requires rocket engine in addition to all jet engines. Center of lift is slightly behind center of mass as should.

[Pecan]

WAAAAAYYYYYY TOOOOOO BIIIIIGGGGGG!!

Start small.

Section 3 of Chapter 2 of my tutorial has a small, easy to fly plane if you'd like to try it - the .craft download link is at the start of the chapter.

If you want a simple splaceplane there is one in Section 4 of Chapter 6.

The actual spaceplanes I use in the campaign are in Section 5 of Chapter 4 and Section 5 of Chapter 7.

Amongst the problems yours has:

No control surfaces that I can see - elevators, ailerons, etc. - so it depends entirely on lift without pitching nose-up to take off.

Just as well because those long rockets at the back will always hit the ground on landing/take-off unless you stay completely flat.

You have just a huge amount of fuel, engines and rockets.

[Voculus]

Whoa, baby! First off, you must view this informative and entertaining tutorial.

Off the bat, the biggest problem is that it's too big. Not that you can't build large planes, but for your first one, you need to start small. It's like shooting a gun. If you're so far from the target, you never hit the mark, then you can't figure out how to fix what's wrong. With that said, you need elevators in the rear, or canards up front to provide pitch authority. Maybe even both! Secondly, because your wheels act as a fulcrum, your ship will never rotate and climb off the runway, until, like you said, the ground falls away when you run out of pavement. Thirdly, procedural wings can be a tricky beast to tame, particularly when they have a very large surface area.

Anyway, enough of my jabbering. Start smaller, and look at the pictorial linked above. It'll be like playing a whole new game!

[Pursuedtank]

That isn't so much an airplane, as it is a monstrosity. Is that all to get one Kerbal into space? If so then that is way to big. Follow Pecan's advice for airplanes, however the problem that you have with not lifting before the end of the runway can be fixed by moving the landing gear to just behind the centre of lift.

[Jetsim]

Well there are flaps on each wing for pitch. I managed to get this flying after removing couple fuel tanks but its extremely unstable and trembels alot. Also log says that fuel tanks are not connected well, but I dont understand how to make attach them properly.

[Master Tao]

Whoa, baby! First off, you must view this informative and entertaining tutorial.

Seriously, read that tutorial. It will explain why the control surfaces on the wings don't work for pitch and why the plane is unstable. The trembling? Looks like too many parts in the fuselage, probably made worse by SAS.

[Spyritdragon]

As the others have said, that thing is a monstrosity. Also, most KSP planes are unstable. Why don't you take the Aeris4A for a spin, see if you can get that to orbit? Its a very good example of a spaceplane, and its not too hard to get into orbit with it.

If you stilll want to go through with this design.

Trembles alot? MoreSpacetapeâ„¢!

Also, all of your load relies solely on your two wings there. Add some canards (that produce relevant amounts of lift) to the front, and add control surfaces to those. Those'll function as elevators - the control surfaces on your wings are ailerons, which are usually used mostly for roll control.

Leave the triple tanks in the rear off - don't need those. Just use fuel from the main body for the rocket engines.

Also, i still advise taking off alot of the fuel tanks, or at least emptying a bunch of em if you really want to keep this structure.

[Jetsim]

Removed rear fuel tanks, added wings in front of large wings with added control surface. Plane now flies well up to 25 000km, but then starts to spin around uncontrollably. Also parts of the plane still tremble even though they are connected with struts.

[Aethon]

Gotta give a shout out to my man cruzan ak. You newbies who are visual learners will love his aircraft tutorials. Short and to the point. He taught me how to fly (no comand pod torque) in KSP.

[xcorps]

Removed rear fuel tanks, added wings in front of large wings with added control surface. Plane now flies well up to 25 000km, but then starts to spin around uncontrollably. Also parts of the plane still tremble even though they are connected with struts.

One or more of your jets lost air and flamed out. This created asymmetrical thrust, causing your plane to pitch and yaw uncontrollably. Spin is when your ship turns around it's center of mass but maintains the same heading and altitude. Yaw is changing heading left and right without changing altitude. Pitch is changing altitude without changing heading.

[Alshain]

You need to temporarily abandon the idea of going to space. If this really is your first plane, you should be starting with an simple atmospheric aircraft and practice take off and landing. Trust me, I did it backward too and things would have been much easier. The main reason is your going to crash a lot on landing and it's easier to retry over and over again from a simple plane than to do it from orbit, which takes forever just getting to the runway. Graduate up to space craft. Your first plane should have a single basic jet engine.

Edited July 23, 2014 by Alshain

[Hodo]

http://tinypic.com/view.php?pic=214carn&s=8#.U8_QRPl_tK8

My first airplane, problems are: Doesnt take off until runway ends and even then it doesnt fly much and flying requires rocket engine in addition to all jet engines. Center of lift is slightly behind center of mass as should.

Ok unlike everyone else I am going to tell you what I see wrong with that thing that could be a plane.

1- It wont take off till the end of the runway because your landing gear are to far behind the CoM, which is causing your point of rotation to be behind the CoM and CoL. Thus you are trying to push the landing gear into the ground, which means the nose WONT lift off the ground. To fix this move your rear most landing gear closer to the CoM of the aircraft.

2- If you are using FAR, it has the aerodynamic properties of a brick, which means it really isn't going to fly well. You slapped some procedural wings on a rocket shape and canted them upwards at about 20-30deg, WHY?

3- I see you have control surfaces on the wings, REALLY long ones. Not sure what you have them set to do, but I can tell you they aren't going to do much with those wings.

4- The jet engines, you have what 8 Turbojet engines on there, and 3 rockets, you can get away with 1/8th of that in turbojets and 1 rocket engine. Right now your craft is to heavy, and I really don't see any intakes for those jet engines.

I can also suggest you read the links that Pecan or Cruzan's video that was posted.

[Jetsim]

http://tinypic.com/view.php?pic=2gwcnc1&s=8#.U9ADRPl_tK8

That plane flies well except that it refuses to turn unless I spin alot with Q and A and change pitch. How to make this plane turn around like good jet plane? Also how to solve fuel problem with mono-engines? they consume all fuel fast and plane starts to spin around in space.

[Alshain]

http://tinypic.com/view.php?pic=2gwcnc1&s=8#.U9ADRPl_tK8

That plane flies well except that it refuses to turn unless I spin alot with Q and A and change pitch. How to make this plane turn around like good jet plane? Also how to solve fuel problem with mono-engines? they consume all fuel fast and plane starts to spin around in space.

That's how it's supposed to work. You can add control surfaces to your tail fin to act as a rudder for yaw control, but your not going to get very steep turns that way, just minor corrections. Though this can be useful for controlling inclination during ascent, gradually rolling back and forth is still a better way to do it. What you described is exactly how a plane changes directions, they roll and either 1. let the air push them slowly around or 2. they roll hard an pull up and let the air push them fast (this is what jet fighters will do, it pulls a lot of G forces though so commercial jets won't do this if they value their business).

Edited July 23, 2014 by Alshain

[Jetsim]

But that plane is really hard to turn and tail fin is rotating. Here was a video where plane turned around quickly and was easy to maneuver. I dont understand why my plane is such hard to maneuver horizontally.

Edited July 23, 2014 by Jetsim

[Alshain]

I can't see any of your images or video but bigger planes are going to turn slower. That's pretty much a universal constant for all vehicles. Never the less, you can also shorten the wings to increase maneuverability.

See this tutorial on plane building

Edited July 23, 2014 by Alshain

[Jetsim]

By the way, where in settings can I switch pitch key binds because W=down and S=up is confusing? I have tried many pitch up and down, but none of those change anything in the game.

[Alshain]

It's in key bindings, but if you change it, it will be for all craft including rockets and it's going to feel backward. W down and S up is done because that's how real planes do it. You push down and pull up, S being lower than W feels more like pulling back on the stick.

[RoboRay]

Well there are flaps on each wing for pitch.

Your wings are in near the center of the plane, meaning surfaces there will provide roughly zero pitch control. The center of mass is the pivot point about which your craft rotates. To move it in a certain direction, the surfaces need need to be well away from the center of mass. It's like rolling a heavy rock with a stick... the longer the stick, the more leverage you can apply by grabbing the stick at the far end.

In the second version you showed, you've got some canards up front for pitch control, so that's helping.

Honestly, though... Put this big giant plane back in the hangar and start over from scratch. Build something small, so it's easy to assemble, easy to design, and easy to fly. Walk, then run. Come back to big giant planes that really don't do anything the little planes can't do later, when you've mastered building the little planes.

Edited July 23, 2014 by RoboRay

[Jetsim]

Main wings are long, so it should get lift from the outer edges of the wings.

[RoboRay]

You get lift from the whole wing. That doesn't have anything to do with the effectiveness of your flight controls. You have to put them in the right place for them to provide certain control axes.

[Clockwork_werewolf]

1: For control in air you want your control surfaces as far from the Center of mass as possible like a lever they work better further out.

2: In space your craft will spin if you have almost any mass off of your thrust. For space your plane wants to have everything symmetrical as possible.

3: In space or high atmosphere (about 23-40k up) you will need to use RCS (which gets used up) or ASAS modules to stop spin and turn your craft. I see you have one on the new plane but two might be better. Their placement doesn't matter.

4: As you go up the atmosphere gets thinner. Control surfaces will have less affect but more importantly air for engines runs out. Jet engines do NOT equally distribute air to all engines when air runs low. Some engines will fire at 100% others at 0% this will SLAM your aircraft into a spin.

5: Use air rams instead of circular intakes for high atmosphere. They take in more air and work much better high up.

6: I see a lot of fuel tanks and structural tanks if you are not using all the fuel in the tanks it could be worth switching to engine nacelles. With the update they take in as much air as a circular intake and hole 40 fuel. This would be useless for a rocket but jet engines are much more efficient.

7: An aircraft should be able to fly at about 50-80 m/s if your's can't you may need more wings. Most aircraft are full of air, imagine an aircraft full of water and that it what a KSP craft full of rocket fuel is like. You may need more wings than it looks like you need.

Edited July 23, 2014 by Clockwork_werewolf

[Alshain]

Main wings are long, so it should get lift from the outer edges of the wings.

He's not talking about lift, he is talking about control. I finally got your pic to load for me. It's hard to tell from one angle but it seems there are many issues here that are going to make a beginner aircraft very difficult. Your center of thrust doesn't look like it will be in line with the center of mass, that's going to make control difficult. You have massive weight issues. How many batteries do you think you need? Those are huge and you don't have much on the craft that consumes electricity. And what is with the O-10's? Those are engines, not RCS thrusters.

[Jetsim]

1: For control in air you want your control surfaces as far from the Center of mass as possible like a lever they work better further out.

2: In space your craft will spin if you have almost any mass off of your thrust. For space your plane wants to have everything symmetrical as possible.

4.As you go up the atmosphere gets thinner. Control surfaces will have less affect but more importantly air for engines runs out. Jet engines do NOT equally distribute air to all engines when air runs low. Some engines will fire at 100% others at 0% this will SLAM your aircraft into a spin.

2. What do you mean by "any mass off of your thrust"?

4. How to prevent that? Jet engines dont work optimally anyway in high altitude.

I removed controllers from main wings, and plane couldnt lift up or flipper around so those big controllers must be main lift force.

Edited July 23, 2014 by Jetsim

[SDEngineer]

2. What do you mean by "any mass off of your thrust"?

4. How to prevent that? Jet engines dont work optimally anyway in high altitude.

For 2, he means any off-centered mass. In the case of your aircraft, you have a number of engines (heavy mass parts) that are mostly distributed on one side (the bottom side) of your aircraft. In air, not a problem (or at least, not an insurmountable one), but once in space, it means that your craft will "push" towards the bottom side, since it is bottom-heavy - the mass isn't evenly distributed.

For 4, you need to monitor the air intake of your engines (you can see it on the fuel status tab), once it drops to just above the point at which you will start having flameouts (which depends on the engine) you will need to shut off the jet engines simultaneously, and then switch on the rockets (generally use action group keys - one assigned to enable/disable the engines as a group, the other to enable/disable the rockets).

Most of the time, if you're doing a SSTO (single stage to orbit) you will level off at below the altitude your engines will flame out on, and start building speed in a level trajectory - as you speed up, your air intakes get more air - then you can gradually start gaining altitude again. Still, at some point, you will have to switch over to rocket power.