Page 34 - MFW Dec 2024

later … well I’ve tried to trim it for you, but it’s always
diving. One click of up trim, now it’s climbing. And if I touch
down elevator, now its diving again. Same problem with
the Ailerons. Its rolling left, now its rolling right … let me
land and have a look. Sound familiar ? 9 times out of 10 its
massive control arms, and the servos have been dialed
back to 30%. Those servos you paid for, you know they
actually move 45 degrees one way, and they move 45
degrees the other way. But when you dial them back to
30% of their throw, now they only move a tiny bit, and you IMAC at Galatea in October
have lost all of the available resolution that you need to fly
straight. So that’s why you can’t trim it. You need to use as
much of the servo travel as you can, and you can only do
this by running smaller arms. Get the low rate running at
something like 70%, and see how much better it flies. And
if you want to run 45 degrees of throw so you can so some
cool 3D stuff, then you will need to run big arms, but you
will need to buy some flash servos that center well.
Harriers, walls, waterfalls, crank shafts, riffle rolls (yep
those are things that young people do when flying 3D) all
Galatea IMAC in November
good fun, but if you are just flying around doing simple
loops &rolls, you probably need to use shorter arms.

Tip Number Two – Expo is you friend. Don’t be scared to
use Expo. It’s in your radio, so use it. We don’t have linear
servos. A long time ago I was told by a reputable flier that
because our servo’s go around in an arc, you need to be
running about 30% expo for things to actually be linear.
Now I’m not sure on the exact math for a servo arm
travelling in an arc, vs linear output, but it tells me that if
you are running under 30% expo, it’s not good. In fact you
are kind of running negative expo. So get using expo, and
see how great it is. Not too much on the elevator is the key.
If you are flying a low elevator rate, between 30% / 40% is Pattern flying at Waharoa in October.
the place to be. If you need more than that, then your low
rate is not low enough. If you are flying 3D stuff, and you
have 45 degrees of throw, then run heaps. Just remember
that too much expo on the elevator in low rate, and you
might find it difficult to fly level. The model maybe
porposing a little when you are trying to hit a level line.
Ailerons is a different story, give it plenty !! 50% … 60% …
get it up there. I’m serious. It’s just going to make it easier
to keep the wings level. I saw a guy fly at a recent
aerobatics event, the model was always twitching on the
ailerons. I had a fly, man it was hard work. So touchy. It
was obvious that the expo on the ailerons was pretty
much non existent. Maybe he had 20%. I landed and
cranked in 50%. He was shocked and stunned !! Are you
mad ??? I said just fly it and see. Then in another 3 flights
time when you are used to it, bump it up to 60 %. Trust me
… it’s the way to go. Just take it up in small steps while you
get used to it.

Birdstrike, Buzzards, and G Forces – Well here is a
story to end the column. I was flying recently at a Galatea
IMAC weekend with my 42% PBG Extra 300. 3.2m wing
span. DA215 up front. All up with fuel, it’s about 20Kg of
flying beast. This model usually has the DA200 4 cylinder
in it, but that is away getting a service. I wanted to test out
the DA215, a monster of a motor. It’s a twin cylinder,
swings a big prop, and the compression is up there. You
feel like you need concrete boots to start it, and I’ve been
running it for 6 months now. Anyway …. I’m flying through
the Unlimited IMAC schedule, having just completed a Buzzard Strike !!

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