Re: Twin Jet problems!

Len Cuff wrote:

On Fri, 29 Jul 2005 21:54:56 GMT, Noah Little <me@xxxxxxxxxxx> wrote:


Len Cuff wrote:

Just bought one of these complete with 2 400 motors. Built fine and
fitted a 3000mh Nimh 9.6 pack and a 35A ESC. Problem is that it just
won't get into the air! Simply flies in a downward direction and land
about 20 feet away. Obviously I'm doing something wrong but any ideas?


Len, sorry, I don't know your experience level, so I don't know how far
you've gotten in troubleshooting, but based purely on the information in
your post, the first thing that ought to be checked (or re-checked) is
balance.


 This is my first attempt at electric but have been flying IC for
years. Checked and rechecked the C of G and it appears to be fine.
I've also just checked the overall weight against what it says in the
book and it should be between 1100 and 1200 grams and mine wieghs in
at 1120 grams so it doesn't appear to be a weight problem. Been
suggested elsewhere that I should bin the props supplied and fit a
pair of 5 x 5 ?

cheers,
       Len

Twin Jet what? I'm guessing here but at that weight it'll be marginal with speed 400 brushed motors and direct drive propellers. From my days of flying .049 craft I can tell you that if it's got a small propeller it'll go like hell once it's going, but you really have to work to get it on the step. My current ride weighs 16oz and flys like a dream on a _geared_ brushed speed 400.

Try launching it _hard_, pointed down slightly (i.e. aim at that spot 20 feet in front of you that you're hitting anyway). Go ahead and let it descend a few feet as it gains airspeed, then _gently_ start leveling out and gaining altitude.

I would be tempted to get an estimate of the thrust -- if the static thrust is less than 1/3 of the model weight then you'll need to be really good; if it's less than 1/4 of the model weight then you're probably wasting your time.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
.