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Somebody really needs to make a hovercraft practice test...

CMS AC wrote:Somebody really needs to make a hovercraft practice test...

There are a few from invitationals in the test exchange.

CMS AC wrote:Finally gotten 2kg now. We're having a problem that we have to make it lighter... -_-

Any high mAh and high C or high A rating batteries that are light? (NiMH or LiPo)

LiPos are significantly lighter than NiMH. There is a trade off however, in that LiPos are significantly more dangerous if handled in properly. NiMH are tough, and can take much more of a pounding. For example, if you charge a LiPo incorrectly, they have a tendency to burst into flames. That's not to say NiMHs aren't dangerous; there are reports of NiMHs exploding because of poor charging. However, this is exceedingly rare.

I use 5500mAh NiMH packs because I like to test for long periods of time. Nice ones includeRacer's Edge. I also heard very good things about Venom. Personally, I prefer to err on the side of safety, so I use NiMH. It's not that difficult to make a craft lighter, I just play around with ballast. If your base is too heavy, I'd recommend switching it out with a thinner one (I use wood!)

Hope this helps!

antoine_ego wrote:
I use 5500mAh NiMH packs because I like to test for long periods of time. Nice ones includeRacer's Edge. I also heard very good things about Venom. Personally, I prefer to err on the side of safety, so I use NiMH. It's not that difficult to make a craft lighter, I just play around with ballast. If your base is too heavy, I'd recommend switching it out with a thinner one (I use wood!)

Hope this helps!

Do you power your lift and thrust motors off the same battery?

windu34 wrote: Do you power your lift and thrust motors off the same battery?

Yup, I ran out of space to add another battery

antoine_ego wrote:

windu34 wrote: Do you power your lift and thrust motors off the same battery?

Yup, I ran out of space to add another battery

Assuming you are using a rheostat to adjust current to the thrust motor, how are you getting accurate readings of current flow under load? Are you turning both the thrust and lift motors on and then measuring current in series to the motor?

We know the resistance of the rheostat from prior measurement, so, ignoring nonlinearity in the rheostat, by measuring the voltage across it, we know the current flowing through it by V = IR.

What's your consistency between runs? We are able to get about plus or minus 0.5 seconds consistently, no matter what distance.

antoine_ego wrote:What's your consistency between runs? We are able to get about plus or minus 0.5 seconds consistently, no matter what distance.

My consistency is about +-0.05 seconds. I wouldn't neglect the nonlinear nature of a potentiometer, that can really screw things up. You don't even need to do a calculation every time you want a new resistance, you can just mark qualitative points on the resistor that are evenly spaced. Then, when you take you data, instead of finding the resistance, you can note: Mark 3, 13.26s, 13.44s, etc.

LittyWap wrote:
My consistency is about +-0.05 seconds

Really??? That's crazy

antoine_ego wrote:

windu34 wrote: Do you power your lift and thrust motors off the same battery?

Yup, I ran out of space to add another battery

So are you using a rheostat, or using flaps?