fractal cat

Hi Everyone,

Hope someone can help.

I've just fitted a new engine (Irvine 46) and when it's running the model's
fuselage vibrates rather a lot. Is there something I can do to either stop
this or minimize it? The model has never been flown and is a Tigre Trainer.

Regards, thanks and safe flying.

Fractal Cat.

paul mcintosh

The prop is balanced when you can set it at any position on the balancer and
it doesn't move from that.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"Fractal Cat"

kevin manley

Good start, and if you've got to the point where you've installed
everything
and started the engine then you are doing quite well. But there's much
more
to learn, so see the next answer......


*then* take it to a club and fly it.

Ah. All together now...."Join a club!" Seriously, if you don't know
of
one nearby then have a look on the BMFA website or ask at your LMS, find
a
club, give them a call and pay them a visit. When you join you should
find
everyone falls over themselves to help and they will solve your
vibration
problem in a flash. They will go over your model with a fine tooth comb
and
help you sort out any minor problems prior to the first flight then give
you
free flying training until you are good enough to go solo. Please don't
be
tempted to try and learn by yourself - it'll end in tears.

My club operates an 80dB noise limit rather than the BMFA norm of 82dB,
so
we tend to use bigger props than usual to keep within the limit. I
would
expect to use 11x6 or 11x7 on a 46, especially for a trainer that
perhaps
doesn't need so much power. Anyone else care to air an opinion?


using

for


Don't know what sort of balancer you have. I have only ever used the
normal
overlapping wheeled contraptions. They come with a steel shaft fitted
with
2 cones. Pull off one of the cones, poke the shaft through the hole in
the
prop, then refit the cone and push it tight up to the prop. Through the
action of the cones, the prop should now be centred on the shaft. Place
the
shaft between the balancer wheels, with the prop horizontal. Let go and
watch the prop - if it rotates of its own accord then the down-going
blade
must be heavier than the up-going blade. Remove the prop and use 400
grit
sandpaper to remove a little material from the back of the heavy blade -
only experience will tell how much! Check the cones are still tight,
refit
to the balancer and repeat as necessary. As Paul M says, it's balanced
when
you can set it in any position on the balancer and it doesn't rotate.

PolyTetraFluoroEthylene. Same stuff as Teflon I believe. It comes in
many
forms, but plumbers use it in the form of a very thin soft white tape
about
half an inch wide, for sealing joints in water pipes. The tape is not
actually sticky, but has a sort of tacky bonds-to-itself quality like
cling-film. Being soft, it squishes to fill small gaps, which is why
it's
useful for padding out any gap between crankshaft and prop. You can get
it
from plumbers merchants, B&Q and the like.

Join a club first. They will help you with all of this.

Regards, Kevin

--
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