[1.1] Drone keeps crashing

[nascarlaser1]

Hi guys! I am new to ksp and I recently built a rocket assisted drone capable of doing a short suborbital flight over Kerbin. The drone works using 2 Rapier engines for regular flight and 1 Hammer solid rocket fuel engines.  To fly it all I need to due to fire it off the launch clamps using the Hammer, wait for the engine to run out of fuel, stage it, then just let the air breathing rapiers take over. This will get it into a suborbital flight, then I  fly suborbital using the closed cycle till the engines run out of oxidizer, then wait for it to deorbit. On the first test flight I ran into a problem with the Rapiers. They take so long to get enough air to start the air breathing mode again after deorbiting, that the ship loses control and starts spinning around rapidly. By the time the engines do kick in, my drone is spinning around so fast its impossible to take control of again. This means that I need to land hope the parachutes can keep it from going boom on impact with the ground. Any suggestions on how to keep the drone from spinning out of control so I can then use the Rapiers to bring it into a soft landing like its supposed to?

 

I also have a second question (not as important, I only thought of it now.) While flying in the atmosphere I noticed that if I try to roll in order to turn, the ship will start rapidly rolling without turning. I can stop the rolling but any attempt to steer results in the same affect that happens when I deorbit, even with 95% fuel left. Any suggestions? I mostly just fly it in a straight line any way since its was designed to due suborbital flight only, and nothing else fancy.

Edited July 16, 2016 by nascarlaser1
I remembered an extra question.

[Snark]

Moving to Gameplay Questions.

7 minutes ago, nascarlaser1 said:

I ran into a problem with the Rapiers. They take so long to get enough air to start the air breathing mode again after deorbiting, that the ship loses control and starts spinning around rapidly. By the time the engines do kick in, my drone is spinning around so fast its impossible to take control of again.

Almost certainly the problem has nothing to do with when your Rapiers kick in.  Having them on doesn't stabilize the plane, they just make it go faster.

The problem is with your ship design:  specifically, it's not aerodynamically stable on reentry.  One very common problem with spaceplane-style craft on reentry is that their CoM may shift a lot during ascent as they burn off fuel.  Very often it will shift to the rear (depending on the ship design), making the plane very unstable, and you don't discover that until you come back into atmosphere.

It's impossible to say just how to fix it without seeing a screenshot of your plane.  If you could post one, we can offer constructive suggestions.

 

[nascarlaser1]

Thank you with for the quick reply. I cannot post a screenshot right now, but I can tell you the specs of the drone. The middle section is made out of a nosecone, a mak2 rocket fue fuselage short, and the detachable hammer booster. The two side stacks are made of a shock nose intake, a liquid fuel tank (can't remember which one,) and the two rapiers. The middle stack has 2 AV-T1 winglet, and the side stacks have 2. The only thing that detaches (on purpose) is the hammer booster.  Thanks again for the quick reply

Edited July 16, 2016 by nascarlaser1

[bewing]

As snark said, the shifing CoM is almost certainly the cause of your problem. This means that the exact placement of your side stacks is vital.

Do you understand how to turn on the CoM and CoL indicators in the VAB, with the Hammer, fuel, and clamps all removed from the plane -- so you can visually inspect the approximate positions of CoL and CoM?

[nascarlaser1]

44 minutes ago, bewing said:

As snark said, the shifing CoM is almost certainly the cause of your problem. This means that the exact placement of your side stacks is vital.

Do you understand how to turn on the CoM and CoL indicators in the VAB, with the Hammer, fuel, and clamps all removed from the plane -- so you can visually inspect the approximate positions of CoL and CoM?

I know how to turn on the CoM and CoL indicators in the SPH (where its built), I assume its the same for VAB. I don't how to remove fuel in SPH or VAB yet but I did check it without the clamps and hammer, and it didn't have thzt big of a change. I even checked CoT to make sure that was good.  

[bewing]

10 minutes ago, nascarlaser1 said:

 I don't how to remove fuel in SPH or VAB yet

Try clicking on a fuel tank, so that you can see the amount of fuel it has in it. That little fuel gauge is actually a slider. You can drag it or click on it and change the amount of fuel in the tank.

[nascarlaser1]

Just now, bewing said:

Try clicking on a fuel tank, so that you can see the amount of fuel it has in it. That little fuel gauge is actually a slider. You can drag it or click on it and change the amount of fuel in the tank.

Thank you very much. I never realized that. I thought the arrow was just there for décor. Thxs again for all your quick replies. I will try to post a screenshot soon of my drone to make all your lives easier.

[bewing]

Took me weeks to realize the silly arrow was not décor.

[nascarlaser1]

20 minutes ago, bewing said:

Took me weeks to realize the silly arrow was not décor.

lol thxs for your help :). Will post a screenshot sooner or later and will try your suggestion to make it work more :).

[nascarlaser1]

2 hours ago, Snark said:

It's impossible to say just how to fix it without seeing a screenshot of your plane.  If you could post one, we can offer constructive suggestions.

 

Does anyone know how to insert a screenshot? I took 3 screenshots of my shuttle using snipping tool but on the forums there is  no way to select them to insert them.

[bewing]

You have to use imgur or some similar service, or have a website of your own. Creating an album is good when it's going to be more than a couple pix. Copy the "direct link" url and paste it in where it says "insert picture from URL".

[Snark]

Relevant:

 

[nascarlaser1]

No need for screen shot :). Following your guys advice about Com and Col I managed to fix it. Thank you