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Old Jul 26, 2007, 12:11 PM
Doug McLaren
Doug McLaren
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Re: UpStar EP Glider by Tower Hobbies

In article <74Upi.4213$b04.3815@trndny06>,
Vegasfan <cbusse1@verizon.net> wrote:

| I've read forums on RC Universe and some of the guys rip the Upstar
| pretty bad. Many had problems with the motor running just a few
| seconds and then dying. Mine has never had that problem. I think
| it's caused by the esc shutting the motor down because it's pulling
| too many amps. Here again, I think it's because it's overpropped.

There's been a large number of planes like this over the years --
speed 500 to 600 can motor, direct drive, 6 to 8 cell NiCd/NiMH pack.

Yes, they tend to be over-propped. Really, what they generally need
is a lower Kv motor (or a gearbox) so they can use a bigger prop, but
instead they go for direct drive, and a prop that's smaller than would
be ideal for the airframe, but is bigger than ideal for the motor. So
they take an inefficient motor, and make it worse by running it
outside of it's `sweet spot'. And this requires a big heavy battery,
making the plane thermal poorly.

What they really need is a lower Kv motor, perhaps a brushless
outrunner, or a gearbox. Then they can use a smaller battery which
saves weight. Going LiPo could save even more weight.

Of course, once you've spent all this money into upgrading the drive
train, you might as well get a better airframe as well.

To be fair, I've never seen this particular model, so maybe some or
all of my comments on the class don't apply.

On the bright side, people sell these things used all the time. I got
a similar 2m electric glider by Thunder Tiger (I think) complete with
all radio gear, batteries and even a charger for $70 at a swap meet,
and it flew as well as any of them.

But there's a huge difference between it and the more `serious'
electric gliders that I now have.

--
Doug McLaren, dougmc@frenzied.us
Is it weird in here, or is it just me? --Steven Wright