SSTO1 = fail. Help please

[Miro Beero]

I cannot seem to figure out why my SSTO attempt keeps having trouble on the runway.

I have FAR installed.

The Center of Mass is right infront of Center of Weight, and directly behind is a center of thrust.

I put on my SAS and still I have issues. I seem to get up to about 65 m / s and the whole thing starts to wobble like crazy on the runway (that's why I tried fixing that with all the wheels). Up until the point I clip a wing somewhere and the whole thing just destroys itself.

What am I missing for takeoff here?

http://imgur.com/a/HEHCm#0

[Xavven]

Looks like a heavy craft with very little wing surface area, and you're also trying to take off at a low speed. To fix this, you'll probably want bigger wings.

[Miro Beero]

Looks like a heavy craft with very little wing surface area, and you're also trying to take off at a low speed. To fix this, you'll probably want bigger wings.

I actually would prefer to keep it on the runway longer for more speed, it just starts wobbling a lot.

I think I am using the biggest wings it allows. So I now have to figure out how to merge a bunch of wings together or something.

[Madrias]

The crooked landing gear isn't helping matters, either. Straighten those out using the Rotate tool and you should eliminate some of the speed wobble.

[Starhawk]

I'll echo the advice about making sure all your landing gear is dead straight.

Happy landings! ...eventually.

[Stochasty]

Nose up posture on the runway + single front gear = wheelbarrow.

What's happening is that, as you gain speed, your rear landing gear are lifting off of the ground, leaving your plane balanced on the single front gear. Not good. The solution is to change your posture to be either level or slightly nose down on the runway.

[Guest]

FAR have in-game analysis tool, learn how to use it.

And gear looks really funny.

[Mad Rocket Scientist]

You could try putting the landing gear just behind the center of gravity

[theend3r]

As other have said, straighten the wheels. Also, taking off should be easy since landing will be 100x harder.

[Randazzo]

With tricycle landing gear (I use that very loosely in this case), as was mentioned before, if you get to balancing on the front wheel alone you will start to wobble and lose control. If you're going to have a nose up orientation on the runway, you need to have enough lift to get completely off the ground. Alternatively, you can add some control authority to the front of your craft to lift the nose first.

[katateochi]

I'd say way too many wheels for that size craft and more wheels can cause more problems. I'd cut it back down to three wheels, make sure the rear pair are positioned just a bit behind the COM so you can get the nose up easily. If you really feel like you need more wheels put them together, so essentially you still only have 3 points of contact (just the rear point are wider). Also have them perfectly perpendicular, angled wheels can work but only in a three wheel config.

[Wanderfound]

As others have been saying:

* Straighten your landing gear.

* Put the rear gear just in front of CoM.

* If you have tailstrike problems, raise the gear on hardpoints.

See the first few posts of the Kerbodyne thread and my build videos (both linked below) for tips.

[Miro Beero]

Success.

I added an extra wing flap on the side near the front and got rid of all the extra wheels, and moved the 2 back wheels up to be with the Center of Mass. That's the big part I think I was missing. The wheels with the COM.

Thanks all.

[Mad Rocket Scientist]

Yay, I'm glad it works!

[Vanamonde]

Moved to the how-to section.

Also, seriously? You're frustrated because your first SSTO isn't working? I've made 46 serious design attempts, only 3 of them work at all, and only 1 of those is reliable and can carry a (small) cargo. You have a long way to go before you can be as frustrated as me.

[Miro Beero]

Moved to the how-to section.

Also, seriously? You're frustrated because your first SSTO isn't working? I've made 46 serious design attempts, only 3 of them work at all, and only 1 of those is reliable and can carry a (small) cargo. You have a long way to go before you can be as frustrated as me.

Who said I was frustrated?

I just couldn't figure out why I couldn't get off the runway with a bigger plane.

[Hodo]

The biggest problem is the placement of the gear, you have to many for the size of that craft, and your primary gear are not straight. They have to much camber which is causing the craft to go one way or the other. Then with the fact that your gear are behind the pivot point of your aircraft (the point just behind your CoM where you CoL is in your screen shot) you are just forcing those gear into the ground making the camber issue worse.

The speed is not a major issue but your lack of wing is. 75m/s is about 140-150kts which is about what most of my SSTOs of that size take off at.

[Miro Beero]

Do most of you use this mod? for wings? or do you build the big wings with a tone of little bits?

http://forum.kerbalspaceprogram.com/threads/29862-0-90-Procedural-Dynamics-Procedural-Wing-0-9-3-Dec-24

[SpacedCowboy]

Yeah, as everyone else has said, It's a landing gear issue, you only need three gears for that craft, they only need to be properly placed.

[Wanderfound]

Do most of you use this mod? for wings? or do you build the big wings with a tone of little bits?

http://forum.kerbalspaceprogram.com/threads/29862-0-90-Procedural-Dynamics-Procedural-Wing-0-9-3-Dec-24

Stock wings for big'uns aren't that hard to do:

Javascript is disabled. View full album

[Hodo]

I use Pwings for almost everything it cuts down on parts count by alot. The wings that Wanderfound shows are great but often lacking in size.

[THX1138]

Are you running an old version of the game? You seem to have no runway lights.

[jarmund]

I cannot seem to figure out why my SSTO attempt keeps having trouble on the runway.

I have FAR installed.

The Center of Mass is right infront of Center of Weight, and directly behind is a center of thrust.

I put on my SAS and still I have issues. I seem to get up to about 65 m / s and the whole thing starts to wobble like crazy on the runway (that's why I tried fixing that with all the wheels). Up until the point I clip a wing somewhere and the whole thing just destroys itself.

What am I missing for takeoff here?

http://imgur.com/a/HEHCm#0

I had a similar issue a while back with my SSTO-prototype. It turned out that it was related to the angled dual landing gear in front that I used.

My theory is that the weight of the craft made the gear twist, and eventually the entire thing weered off the runway. The fix was:

- Only one gear in front

- No angling

- Move the rest of the landing gear around so that it takes most of the weight, leaving the front one not as heavily loaded

[William Nye]

The Center of Mass is right infront of Center of Weight, and directly behind is a center of thrust.

Is your center of lift in front of the center of mass? That'll help. You'll also need more wing surface area.

[Sorcie]

I didn't like the SPH and planes previously but been playing a long time and in SPH a lot lately.

Any time I have takeoff wobble and bad pull to left or right it's:

1) Strut the aircraft. Wing sections must be strutted to avoid the lift surfaces doing erratic things. They need to stay semi-rigid and stay on their intended planes.

2) Landing gear alignment as mentioned

3) Bad or misaligned symetry somewhere