Moebius FS-1 Build

[Guest]

A 12 pole motor would

A 12 pole motor would be better for this application I think.

The Robbe Roxxy range of motors would be worth a look.

[Guest]

A couple of other things

A couple of other things worth a try-

Use the exponential function in your TX to create a throttle curve.

Try fitting a gyro on the steering. Not sure if that will work, but with gyros dirt cheap these days, it's worth a shot if nothing else works.

[bigdave]

Thanks Andy.
I still

Thanks Andy.
I still have to try reprograming the ESC's.
Plus I need more foam for stability. I was able to get the CG where I wanted it but it is way too touchy to fly. I may have to trade being able to roll for being able to run period. BD.

[bigdave]

I spent some time on

I spent some time on the FS-1 this morning.
I reprogrammed the ESC's for a slower start. They seem to work better now.
I also added a lot more foam to make it more stable.
I also had to add more to compensate for the 3 OZ of extra weight from the more powerful 4500MA battery. I was running a 2000MA battery but the run time would have been short.
I will report on how these changes worked after I can get some pool time. BD.

[crazy ivan]

This weekend's progress:

http://www.youtube.com/v/8y-akaFbtLE

This weekend's progress:

[youtube]http://www.youtube.com/v/8y-akaFbtLE[/youtube]

[Guest]

Has it got a leveller

Has it got a leveller fitted?

Also perhaps 50% exponential (or higher) dialled in to make the pitch control more docile.

[bigdave]

No pitch control yet. I

No pitch control yet. I had to almost keep full back on the stick to keep it from diving.
I did run much better this time and I am getting closer.
The foam really helped although I need to move the CG closer to the bow. Any FW movement and it wants to dig in and dive.
Once DonO's pool is open it will be easier to trim out.
It did look quite good for a few seconds.
Almost made me look like I knew what I was doing. BD.

[JWLaRue]

Dave,

....interesting that it wants to

Dave,

....interesting that it wants to nose-dive when it is right-side up as well as upside down.......

Where is the CG located now?

-Jeff

[Guest]

Definitely nearly there. Maybe a

Definitely nearly there. Maybe a bit more foam in top and a bit more lead in the belly?

[bigdave]

I tried to have the

I tried to have the CG right about at the hatch center. I thought that would be a good starting point. BD.

[Guest]

That looks about right to

That looks about right to me. Any further forward and it may start to weathercock. Sounds like too low a metacentric height, and perhaps reduce the throw for pitch control a bit or add the exponential I mentioned before.

[bob_eissler]

Pretty interesting Dave. Does your

Pretty interesting Dave. Does your thrust axis go thru your CG? I have a wild idea of controlling pitch by using a sliding weight moved by a servo with an angle keeper. It seems like it would be simple but effective on the flying sub since its length is so short. Haven't gotten around to experimenting with it yet.

[bigdave]

Well! http://www.subcommittee.com/forum/icon_rolleyes.gif
I have thrown

Well!
I have thrown in the towel on the brushless motors in the FS-1.
It is not worth all the time trying to get them to run right.
They are way to powerful for the FS-1 anyway.
I am working on installing a 380 sized brushed motor. It will be a tight fit as the brushless is shorter but it looks like it may work.
I have one of the motors mounted and have tested it with the AstroFlight watt meter. I get 6 amps and some good thrust which should be fine. This is about 1/2 the power of the brushless.
It should still be zippy but not an uncontrolable beast.
I was able to do some more testing over the weekend and moved the CG further foreword. It was better but anything over a crawl and she wants to dive.
Hopefully now with better control of the throttles I can get her dialed in. BD.

[bcliffe]

It was better but anything

It was better but anything over a crawl and she wants to dive.
Hopefully now with better control of the throttles I can get her dialed in. BD.

Dave,

I think this is actually a function of the hull and not your setup. Ran mine for the first time last weekend and was extremely happy with how it performed. Using pumps so it is not terribly fast, but can do a good walking pace. Full throttle forward puts it in a graceful dive, to run on the surface you actually have to be way back on the stick. Rick's and Ted's FS1 behave the same way.



Cheers
BC

[bigdave]

Hi Ben,
I had a

Hi Ben,
I had a feeling that it was the case. Thanks for the input.
Looks like it will all fit in the cylinders.
I am using a Viper 10 for each motor and bench testing looks great.
The mixing and motor control is nice and smooth now.
Here are the basic parts of the two power units. BD.