Leaning Plane

[locustgate]

So I'm still trying to make a Spaceplane, and my most recent problem is my plane seems to lean to one side when the engines start, the CoM looks good. Additionally the plane during descent pulled to the tilted to the forward left, on a full tank. On a simirelated note do Air intakes act similar to engines or like monopropelent tanks?

Plane:http://imgur.com/HZbqzMu,eUXtHay,RWBxPxL#0

Edited January 5, 2015 by locustgate

[Pecan]

Stock or FAR?

The balance looks ok and you should have enough thrust but there doesn't look to be enough wing on there, or possibly rudder.

Almost certainly not enough air-intakes for much performance though - 4-8 per engine will let you go much higher and therefore faster.

Air intakes don't act like engines OR monopropellant fuel tanks - they act like air intakes. Those I see on there are also Liquid Fuel tanks.

If there really are only two intakes on that plane my best guess for your main issue is that you're getting uneven thrust from the two jets - possibly one of them is flaming-out even on the runway.

[locustgate]

Stock or FAR?

The balance looks ok and you should have enough thrust but there doesn't look to be enough wing on there, or possibly rudder.

Almost certainly not enough air-intakes for much performance though - 4-8 per engine will let you go much higher and therefore faster.

Air intakes don't act like engines OR monopropellant fuel tanks - they act like air intakes. Those I see on there are also Liquid Fuel tanks.

If there really are only two intakes on that plane my best guess for your main issue is that you're getting uneven thrust from the two jets - possibly one of them is flaming-out even on the runway.

Stock, only mod is kethane and final frontier.

If the balance is ok then why is the plane leaning it gets worst with the engines on and impossible.

I meant do the air intakes need a physical connection to the jet engines to supply air or do they need to be on the plane to supply air.

Edited January 4, 2015 by locustgate

[LethalDose]

my plane seems to lean to one side when the engines start

Is this while the plane is still on the ground? Because this may be due to cambered landing gear instead of CoM/T imbalance.

[Pecan]

Post the craft file and I'll give it a go, otherwise as I said before uneven thrust caused by too little air is my best guess. NMI.

[locustgate]

Post the craft file and I'll give it a go, otherwise as I said before uneven thrust caused by too little air is my best guess. NMI.

Any idea where for free.

The leaning seems to of been the wheels, I moved the front wheel back more. I also moved the 2 jet engines to the outside and put enough intakes to airdrown a fish.

The CoM moves forward.....alot. When I hit 15km it likes to pitch right.

Edited January 4, 2015 by locustgate

[LethalDose]

Ideally, your CoM should be in front of your CoL, and currently your CoM is behind CoL.

It looks like your CoM will typically move forward as your fuel is burnt off, but starting is gonna be tricky and at 15 km, it may still be problematic.

You may also want to consider adding some reaction wheels to improve stability.

[Pecan]

WD LD - you nailed the gear issue :-)

@ locustgate - dropbox is as good a repository for sharing files as anywhere else.

[locustgate]

Ideally, your CoM should be in front of your CoL, and currently your CoM is behind CoL.

It looks like your CoM will typically move forward as your fuel is burnt off, but starting is gonna be tricky and at 15 km, it may still be problematic.

You may also want to consider adding some reaction wheels to improve stability.

Theres a drone core right behind it.

Plane File (tell me if the link doesn't work):https://www.dropbox.com/s/imhzsqmp04a23at/Rainbird%20MKI.craft?dl=0

It likes to lean to the right, but the CoL and CoM are stable, full and empty.

Edited January 4, 2015 by locustgate

[LethalDose]

WD LD - you nailed the gear issue :-)

Yeah, thats what it basically always is when players describe that problem.

It likes to lean to the right, but the CoL and CoM are stable, full and empty.

Well, thats a problem then because the CoL being stable in front of the CoM means that its always in a less than ideal balance. That plane's natural state will be to go into a stall at speed. The fact that its twisting up and to the right very well may be the first parts of that stall.

[Pecan]

Theres a drone core right behind it.

Plane File (tell me if the link doesn't work):https://www.dropbox.com/s/imhzsqmp04a23at/Rainbird%20MKI.craft?dl=0

It likes to lean to the right, but the CoL and CoM are stable, full and empty.

Tested:

1. Under the port wing were two fuel-lines, one in and one out of the core. Loops like that can do all sorts of funky things to fuel-flow but particularly would have made the 'plane unbalanced since it wasn't duplicated under the starboard wing. Since the 'plane was pulling to the left it was presumably burning fuel in the starboard, but not port, wing-tanks. Deleted all fuel lines and had no problems with imbalance.
   
2. Gear was so far back I could not rotate on the runway so could only climb after 'falling off' the end of it. Moved gear forward but not enough pitch-authority to rotate.
   
3. Added elevon-1s to nose-wings (as in your picture but not the craft file) - CoL still behind CoM. Able to rotate, max 8-degrees to avoid tail-strike.
   
4. Climb-out ok but once above 10-15km either had to climb (almost) vertical to rapid flame-out or could not maintain positive pitch. Maybe that heavy monopropellant just behind the cockpit. Max altitude achieved 35km.
   

[DivisionByZero]

Looks like Pecan found the issue for your plane pulling. I also had a plane that would start pulling over one side and then I discovered it was burning fuel asymmetrically for some reason. TAC fuel balancer has a way to keep the fuel even, however and that's what I used.

Good luck!